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METHOCEL Cellulose Ethers Technical Handbook

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Page 1: METHOCEL Cellulose Ethers Technical Handbookfoodsci.rutgers.edu/carbohydrates/METHOCEL Cellulose Ethers...Applications for METHOCEL Cellulose Ethers ... ethers are also soluble in

METHOCEL Cellulose EthersTechnical Handbook

Page 2: METHOCEL Cellulose Ethers Technical Handbookfoodsci.rutgers.edu/carbohydrates/METHOCEL Cellulose Ethers...Applications for METHOCEL Cellulose Ethers ... ethers are also soluble in

ContentsAn Introduction to METHOCEL Cellulose Ethers . . . . . . . . . . . . . . 1

General Properties of METHOCEL Cellulose Ethers. . . . . . . . . . . . 3

Applications for METHOCEL Cellulose Ethers. . . . . . . . . . . . . . . . 7

Regulated Uses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

How To Prepare Aqueous Solutions of METHOCEL . . . . . . . . . . . 11

How To Prepare Solutions of METHOCEL in Nonaqueous

Solvents and Nonsolvent Media . . . . . . . . . . . . . . . . . . . . . . . . 14

Properties of METHOCEL in Powder Form . . . . . . . . . . . . . . . . . . 15

Properties of Solutions of METHOCEL. . . . . . . . . . . . . . . . . . . . . 16

Thermal Gelation in Aqueous Media . . . . . . . . . . . . . . . . . . . . . . 22

Properties of Films of METHOCEL . . . . . . . . . . . . . . . . . . . . . . . . 26

Analytical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Handling Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

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* Trademark of The Dow Chemical Company

METHOCEL* cellulose ethers arewater-soluble polymers derived fromcellulose, the most abundant polymerin nature. For over 50 years theseversatile products have played animportant role in foods, cosmetics,pharmaceuticals, latex paints, con-struction products, ceramics, and ahost of other applications.

METHOCEL products are used asthickeners, binders, film formers, andwater-retention agents. They alsofunction as suspension aids, surfac-tants, lubricants, protective colloids,and emulsifiers. In addition, solutionsof METHOCEL thermally gel, aunique property that plays a key rolein a surprising variety of applications.You won’t find this valuable combina-tion of properties in any other water-soluble polymer.

Multifunctionality and EfficiencyImprove Formulation Economy

The fact that so many useful proper-ties are simultaneously present andoften act in combination can be a significant economic advantage. In many applications, two, three, ormore ingredients would be requiredto do the same job performed by asingle METHOCEL product. In addi-tion, METHOCEL cellulose ethers are highly efficient, often yielding optimum performance at a lower concentration than that required with other water-soluble polymers.

Range of Products Offers Formulating Versatility

The broad range of METHOCELproducts available is certainly onereason they’ve been used successful-ly in so many different applications.There are two different chemicaltypes and each is available in differ-ent grades, physical forms, and viscosities. By choosing a specificMETHOCEL product, it’s possible to

obtain the optimum degree of thick-ening, binding, moisture retention,and other properties desired in agiven formulation.

Premium and Food Grades forFood and Drug Applications

METHOCEL Premium and Foodproducts have long been used by the food and drug industries. Bothmethylcellulose and hydroxypropylmethylcellulose are recognized asacceptable food additives by the U.S.Food and Drug Administration (FDA)and are listed in the Food ChemicalsCodex and the International CodexAlimentarius. Both are included in theUnited States Pharmacopoeia (USPXXI). Methylcellulose is consideredGenerally Recognized As Safe(GRAS) by the FDA.

Standard Grades for Other Applications

Standard grade METHOCEL prod-ucts have the same performanceproperties as Premium grades. The major difference is that Standardgrades can have slightly higher levelsof impurities. Standard grades are notapproved for use in foods, althoughsome Standard grade products maybe used as components of containerscoming in contact with food (indirectfood additive).

Viscosity Grades From 3 to100,000 mPa·s

METHOCEL cellulose ether productsare available in various viscositygrades, ranging from 3 to over200,000 mPa·s.† Because the viscosityof a solution depends on the concen-tration of METHOCEL, this widerange of product viscosity allows youto obtain the viscosity you want in aformulation while using a concentra-tion that gives the desired level ofother performance properties.

Available as Powders, Surface-treated Powders, and in GranularForm

For further formulating versatility,METHOCEL products are available in three different forms: powder, surface-treated powder, and granular.The form influences the techniquesused in making solutions. Untreatedpowders are soluble in cold water butmust be thoroughly dispersed beforethey begin to dissolve. Surface-treatedpowders and granular products canbe added directly to aqueous systems.The dissolution of these products canbe controlled by a shift in pH.

Techniques commonly used inpreparing solutions with differentphysical forms of METHOCELproducts are summarized on pages 11-14 of this handbook.

Key to Product Nomenclature forMETHOCEL Products

METHOCEL is a trademark of TheDow Chemical Company for a line of cellulose ether products. An initialletter identifies the type of celluloseether. “A” identifies methylcelluloseproducts. “E”, “F”, “J”, and “K” identifydifferent hydroxypropyl methylcellu-lose products.

The number that follows identifies the viscosity in millipascal-seconds(mPa·s) of that product measured at2% concentration in water at 20°C. Indesignating viscosity, the letter “C” isfrequently used to represent 100 andthe letter “M” is used to represent 1000.

Several different suffixes are alsoused to identify special products. “P” is sometimes used to identifyMETHOCEL Premium grade products.“LV” refers to special “low viscosity”products. “G” identifies “granular”products. The letter “S” identifies“surface-treated” products, and “CR”

1

An Introduction to METHOCEL Cellulose Ethers

†Note: mPa.s (millipascal-seconds) is equivalent to centipoise. All solution viscosities are measured with Ubbelohde viscometers at 2% concentration in water at 20˚C (68˚F).

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denotes a controlled-release grade.Developmental grades are denotedby the letter X plus a second letter(usually U or Y) plus a five-digit code.

There are also a number of special-purpose METHOCEL products devel-oped for cosmetics, pharmaceuticals,ceramics, and other applicationswhich have different systems ofnomenclature. For example, METHOCEL 40-Series productsmake up a family of special surface-treated products for cosmetic formu-lations.

Example A: METHOCEL A4CPremium is the designation for aPremium grade methylcellulose prod-uct having a viscosity of 400 mPa·s.

Example B: METHOCEL J5MS is a Standard grade hydroxypropylmethylcellulose product with a viscos-ity of 5,000 mPa·s, which has beensurface-treated for easy dispersion.

How To Get Started FormulatingWith METHOCEL

To completely evaluate how METHOCEL cellulose ethers canimprove quality, performance, andeconomy in your formulations, you’llwant to try them in your own lab.Whether you are developing anentirely new product or working toimprove an existing one, chances are you’ll find a METHOCEL productthat’s ideally suited to your needs.

Free Samples and Literature Available

Sample quantities of METHOCELproducts are available free of chargefor your developmental work. You canobtain samples by calling your localDow sales office or one of the num-bers listed on the back cover of thisbrochure. Literature covering the useof METHOCEL products in many ofthe applications listed on pages 7-9of this handbook is also available on

request. Just tell us what types of formulations or products you areevaluating, and we’ll send you all the current literature that applies.

Our Technical Service andDevelopment Staff Can Help

Talking with someone on ourTechnical Service and Development(TS&D) staff can save you a greatdeal of formulation time. In certainapplications, a blend of METHOCELproducts may give the best results,and the details may have alreadybeen worked out by someone in ourlab. We have technical personnelwho specialize in foods, ceramics,paints, cosmetics, pharmaceuticals,construction products, and other spe-cific uses for METHOCEL products.By taking advantage of their experi-ence with METHOCEL, you’ll get ahead start with your formulation andbe certain of getting the most out ofthese versatile products.

Call Your Dow Representative

Again, if you would like samples,additional literature, or technicalassistance, don’t hesitate to call. Call your local Dow sales office orone of the numbers listed on theback cover of this brochure. Calltoday. The sooner you get startedformulating with METHOCEL, thesooner you’ll start seeing improvedperformance and economy in yourproducts.

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General Properties of METHOCEL Cellulose EthersGeneral properties common to thewhole family of METHOCEL celluloseether products are listed below.Individual METHOCEL productsexhibit these properties to varyingdegrees and may have additionalproperties that are desirable for spe-cific applications. Detailed informationon the performance properties ofMETHOCEL products can be foundon page 15-21.

Water solubility. METHOCEL cellu-lose ethers dissolve in water with nosharp solubility limit. Surface-treatedand granular METHOCEL productscan be added directly to aqueoussystems. This feature providesexceptional handling flexibility andcontrol of solubilization rate. Althoughuntreated METHOCEL powders aresoluble in cold water, they must firstbe thoroughly dispersed in the waterto prevent lumping. Dispersion tech-niques are described on pages 11-13.The maximum concentration is limit-ed only by solution viscosity.

Organic solubility. Certain types andgrades of METHOCEL celluloseethers are also soluble in binaryorganic and organic solvent/watersystems, providing a unique combi-nation of organic solubility and watersolubility.

No ionic charge. METHOCEL cellu-lose ethers are nonionic and will notcomplex with metallic salts or otherionic species to form insolubleprecipitates.

Thermal gelation. Aqueous solutionsof METHOCEL products gel whenheated above a particular tempera-ture, providing controllable quick-setproperties. Unlike gels formed by pro-tein thickeners, the gels go back intosolution upon cooling.

Surface activity. METHOCEL prod-ucts act as surfactants in aqueoussolutions to provide emulsification,protective colloid action, and phasestabilization. Surface tensions rangefrom 42 to 64 mN/m. The surfacetension of water is 72 mN/m; a typicalsurfactant has a surface tension of 30mN/m.

Metabolic inertness. Used as foodand drug additives, METHOCELproducts do not add calories to thediet.

Enzyme resistance. Enzyme-resistant METHOCEL productsprovide excellent viscosity stabilityduring long-term storage.

Low taste and odor. METHOCELcellulose ethers have excellent (low)flavor and aroma properties, which isimportant in food and pharmaceuticalapplications.

pH stability. METHOCEL celluloseethers are stable over a pH range of2.0 to 13.0.

Water retention. METHOCEL cellu-lose ethers are highly efficient water-retention agents. This is valuable infood products, ceramics, coatings onadsorbent construction substrates,and many other applications.

Thickening. METHOCEL celluloseethers thicken both aqueous andnonaqueous systems. The viscosityis related to the molecular weight,chemical type, and concentration ofthe specific METHOCEL product.

Film formation. METHOCEL prod-ucts form clear, tough, flexible filmsthat are excellent barriers to oils andgreases. In food applications, thisproperty is often used to retain moisture and prevent oil absorptionduring cooking.

Binding. METHOCEL celluloseethers are used as high-performancebinders for pigments, paper, tobaccoproducts, structured foods, pharma-ceutical products, and ceramics.

Lubrication. METHOCEL productsare used to reduce friction in rubber,cement, and ceramic extrusions.They are also used to improvepumpability of concrete and sprayplasters, such as stucco, and in foodapplications as lubricity aids in extru-sion and other forming processes.

Suspending. METHOCEL productsare used to control settling of solidparticles, for example, herbs andspices in salad dressings, solids inceramic slips, and antacid suspen-sions.

Protective colloidal action.METHOCEL products are used toprevent droplets and particles fromcoalescing or agglomerating.

Emulsification. METHOCELcellulose ethers stabilize emulsionsby reducing surface and interfacial tensions and by thickening the aqueous phase.

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Nonaqueous Solvent Solubility

In general, binary solvent systemsfunction more effectively withMETHOCEL products than single solvents. Where alcohols comprisepart of the binary solvent, solubilityimproves as the molecular weight ofthe alcohol decreases. Table 1 listsseveral compounds which are typicalof the types of solvents that can beused with certain METHOCEL cellu-lose ether products.

Table 1: Typical Nonaqueous SolventsUsed With METHOCEL Cellulose Ethers

• Furfuryl alcohol• Dimethyl formamide• Dimethyl sulfoxide• Methyl salicylate• Propylene carbonate• Formic acid• Glacial acetic acid• Pyridine• Mixtures of methylene chloride and

ethyl, methyl, or isopropyl alcohols• Mixtures of chloroform and methanol

or ethanol• N-Methyl pyrrolidone

Solvent Solubility at ElevatedTemperatures

METHOCEL E and METHOCEL Jcellulose ether products possessstructures that provide unusual solubility properties. They are solublein certain nonaqueous media at elevated temperatures, permitting the formulation of mixes which canbe fabricated by techniques of extru-sion, hot-melt casting, and injectionand compression molding. Examplesof suitable “hot solvents” are found inTable 2.

METHOCEL 310 Series Products

METHOCEL 310 Series products are granular, high-viscosity materials(Table 3) that are sold only in Europeat this time. Controlled granulometryprovides good dry-flow properties,low dust formation, and lump-freedispersibility in water as well asorganic solvents. Their carefully balanced level of substitution rendersthem soluble in both water and certain organic solvents or blends of solvents (Table 4). METHOCEL310 cellulose ether products can be added directly to any solvent or blend of solvents under normal agitation. When using solvent blends there is no need to pre-dispersethe product in a nonsolvent or low-solvent component.

4

SolventBoiling Point

°CSolubility Point

°CDegree ofSolubilitya

GlycolsEthylene glycol 197.3 158 CDiethylene glycol 244.8 135 CPropylene glycol 188.2 140 C1,3-Propanediol 214 120 CGlycerine 290 260 PDOWANOL* EE ethylene 134.7 120 C

glycol, ethyl etherDOWANOL* TPM 242.4 160 P

tripropylene glycol, methyl ether

EstersEthyl glycolate 160 110 CGlyceryl monoacetate (Acetin) 127 100 C

at 4 mbarGlyceryl diacetate (Diacetin) 123-133 100 C

at 5 mbarAmines

Monoethanolamine 170-172 120 CDiethanolamine 268-269 180 C

Table 2: Representative Solvents for METHOCEL E and METHOCEL J Cellulose Ether Productsat Elevated Temperatures

* Trademark of The Dow Chemical Companya C= completely soluble; P= partially soluble

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5

Physical Form Slightly off-white granules

Table 3: Typical Properties for METHOCEL 310

Table 4: Some Typical Solvents and Solvent Blends for METHOCEL 310

Solution Appearance

Clear, Hazy,Smooth Structured Swellable Insoluble

Ethanol (EtOH)

Methanol (MeOH)

Ethanol/H2O 40/60

Methanol/H2O 40/60

Methylene chloride (MeCl2)

MeCl2/EtOH 84/16

MeCl2/MeOH 84/16

Tetrahydrofuran (THF)

THF/H2O 90/10-80/20

Isopropanol

Isopropanol/H2O 90/10-60/40

Isopropanol/MeCl2

1,1,1-Trichloroethane

Polypropylene glycol

Polypropylene glycol/H2O 70/30delayed thickening

Butylglycol

Butylglycol/H2O 50/50

Dioxane

Acetone

Cellosolvea

Dimethylformamide

DOWANOL* PM

••

••

••

••

••

••

••

* Trademark of The Dow Chemical Companya Trademark of Union Carbide Corporation

Solvents

Solvent Type after 1 hour after 24 hoursin methanol (MeOH) 500 mPa.s 650 mPa.sin ethanol (EtOH) 600 mPa.s 900 mPa.sin methylene chloride (MeCl2) 7,500 mPa.s 10,000 mPa.s

Moisture (as packaged) max. 8%

Sodium chloride max. 1.5%

Particle size ca. 100-500 micron

Nominal viscosity1% Brookfield RVT,RT, 20 rpm

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Chemistry of METHOCEL

METHOCEL cellulose ether productsare available in two basic types:methylcellulose and hydroxypropylmethylcellulose. Both types ofMETHOCEL have the polymericbackbone of cellulose, a natural carbohydrate that contains a basicrepeating structure of anhydroglu-cose units (Figure 1). During themanufacture of cellulose ethers, cellulose fibers are heated with caustic solution which in turn is treat-ed with methyl chloride, yielding themethyl ether of cellulose. The fibrousreaction product is purified andground to a fine, uniform powder.

Methylcellulose is made using onlymethyl chloride. These are METHOCELA brand products. For hydroxypropylmethylcellulose products (METHOCELE, F, J, and K brand products), propy-lene oxide is used in addition tomethyl chloride to obtain hydroxypropylsubstitution on the anhydroglucoseunits. This substituent group,–OCH2CH(OH)CH3–, contains a sec-ondary hydroxyl on the number twocarbon and may also be consideredto form a propylene glycol ether ofcellulose. These products possessvarying ratios of hydroxypropyl andmethyl substitution, a factor whichinfluences organic solubility and the thermal gelation temperature of aqueous solutions.

There are also special-gradeMETHOCEL products available thathave been formulated to meet therequirements of specific industries.

Degree of Substitution

The amount of substituent groups onthe anhydroglucose units of cellulosecan be designated by weight percentor by the average number of sub-stituent groups attached to the ring, aconcept known to cellulose chemistsas “degree of substitution” (D.S.). Ifall three available positions on eachunit are substituted, the D.S. is desig-nated as 3, if an average of two oneach ring are reacted, the D.S. isdesignated as 2, etc.

The number of substituent groups onthe ring determines the properties ofthe various products. METHOCEL Acellulose ether contains 27.5 to31.5% methoxyl, or a methoxyl D.S.of 1.64 to 1.92, a range that yieldsmaximum water solubility. A lowerdegree of substitution gives productshaving lower water solubility, leadingto products that are only soluble incaustic solutions. Higher degrees ofsubstitution produce methylcelluloseproducts that are soluble only inorganic solvents.

In the METHOCEL E, METHOCEL F,and METHOCEL K cellulose etherproducts, the methoxyl substitutionis still the major constituent (Table 5).The molar substitution (MS) reportsthe number of moles of hydroxy-propyl groups per mole of anhydro-glucose. In the METHOCEL J and310-Series products, the hydroxy-propyl substitution is about 50% ofthe total substitution.

6

HO

HOH

H

H

CH2

O

CH3

HO

O

CH3 H

O

Figure 1: Typical Chemical Structures of METHOCEL Products

H

OH

H

O

H

CH2

O

CH3

CH3

HHO

HO

H

H

H

CH2

O

CH3

HO

O

H3C H

O

OH

n-2

HO

HOH

H

H

CH2

O

CH2CHCH3

HO

O

CH3

OO

HH

O

H

CH2

O

CH3

CH3

HHO

HO

H

H

H

CH2

O

CH3

HO

H

O

OH

n-2OH

CH3CHCH2

O

HO

Hydroxypropyl MethylcelluloseMETHOCEL E, METHOCEL F, METHOCEL J, and METHOCEL K brand products

MethylcelluloseMETHOCEL A brand products

ProductMethoxyl degreeof substitution

Methoxyl%

Hydroxypropyl molar substitution

Hydroxypropyl%

METHOCEL A 1.8 30 — —METHOCEL E 1.9 29 0.23 8.5METHOCEL F 1.8 28 0.13 5.0METHOCEL J 1.3 18 0.82 27METHOCEL K 1.4 22 0.21 8.1METHOCEL 2.0 25 0.8 25310 Series

Table 5: Degree of Substitution for METHOCEL Products

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The diverse products and processeslisted here all have one thing in com-mon: All benefit significantly fromremarkably small concentrations ofMETHOCEL cellulose ethers. In mostcases, the major benefits are improvedphysical properties, but in manyapplications there are improvementsin processing efficiency and overalleconomy as well.

For more detailed information on anyof these applications, contact yourlocal Dow sales office or call one ofthe numbers listed on the back coverof this brochure.

Adhesives

Carpet backsizing compounds.METHOCEL products impart excel-lent foaming characteristics or “panfroth” to backsizing compounds. Thishelps keep the adhesive in the glueline instead of soaking into the back-ing materials. Also, due to thermalgelation, adhesives set quickly anddry faster at elevated temperatures.

Leather processing adhesives.METHOCEL cellulose ethers areused to paste hides to smooth porcelain or glass surfaces in leather drying processes. Because of itswater retention efficiency and thermal gelation, METHOCEL is much moreeffective than starch-based pastes.

Plywood laminating adhesives.METHOCEL products are used inplywood laminating adhesives to con-trol viscosity in glues for plywoodmanufacture. Thermal gelation andthickening properties of METHOCELproducts keep the adhesive fromsoaking into the wood.

Cigar and cigarette adhesives.Safe and efficient, METHOCEL prod-ucts have long been used as bindersfor reconstituted tobacco sheets andas adhesives for cigar and cigarettemanufacture.

Wallpaper pastes. Used as the primary adhesive in dry mixes,METHOCEL cellulose ether providesthe wet tack required to hold a varietyof paper types on the wall, yet hasexcellent slip properties so patternscan easily be matched. In premixedpastes, METHOCEL is used to con-trol viscosity and improve wet tack.Pastes made with METHOCEL cellu-lose ethers are easily cleaned up withwater and don’t provide a source ofnourishment for insects.

Latex adhesives. METHOCELproducts are used as thickeners in a variety of latex adhesives, such asadhesives used in shoe manufactur-ing. Fast drying speeds and high wet-tack strength due to thermalgelation are key benefits in many of these applications.

Agricultural Chemicals

Dispersing agents. METHOCEL cel-lulose ethers are used as suspendingand dispersing aids for wettable pes-ticide and fertilizer powders. Theyprovide high wet tack and adhesionto waxy plant surfaces. Chemicallyinert and nonionic, METHOCEL cellu-lose ether is compatible with a widerange of active ingredients.

Spray adherents. Spray adherentsor “seed stickers” made withMETHOCEL products effectively bindpesticides, inoculants, and nutrientsto seeds. METHOCEL products fea-ture low plant toxicity and won’t harmgerminating plants.

Ceramics Processing

Tape casting. Use of METHOCELproducts provides better flow and leveling and more uniform thickness.Low sodium residues provide thepurity necessary for electronic items.Thermal gelation reduces bindermigration and surface faults.

Extrusion forming. Used as a tem-porary binder and processing aid,METHOCEL cellulose ethers allowprecise control of rheology in ceramicmixes, permitting broader operatingranges. Lubricity reduces energy con-sumption and die wear, and promotessmoother surfaces. Thermal gelationpermits extrusion of extremely deli-cate, thin-walled shapes without sagor deformation.

Dry and isostatic pressing.METHOCEL products provide optimumgrain lubrication for tighter, more uni-form packing. The results are morepredictable green densities, lessshrinkage during firing, and higherfired strengths.

Glazes/porcelain enamel.METHOCEL cellulose ethers improvecontrol of viscosity and rheology andfire out completely in the kiln.

Injection molding. Use of METHOCELcellulose ethers provides highergreen densities and better greenstrength. In high-temperature coat-ings/refractory mixes and mortars,METHOCEL improves workability and application properties. BecauseMETHOCEL products have low ionicsalt residues, they won’t lower melt-ing points. In fact, they can permit areduction in use of plasticizers withlow melting points.

Chemical Specialties

Resins. METHOCEL cellulose ethers are used to control rheologyand as a colloidal stabilizer in a vari-ety of epoxy, fiberglass, and urea-formaldehyde resins. METHOCELprovides ideal flow and leveling char-acteristics, plus quick-set propertiesdue to thermal gelation.

Rubber. METHOCEL products are used as mold-release agents, stabilizers, and thickeners in rubberlatexes. METHOCEL cellulose etherscontribute to more uniform drying andless pinholing.

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Applications for METHOCEL Cellulose Ethers

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PVC suspension polymerization.METHOCEL products are used inPVC polymerization as primary andsecondary suspension agents. Theyprovide excellent particle size control,good porosity for improved plasticizerabsorption, low reactor scaling, andhigh bulk densities.

Construction ProductsDrywall tape-joint compounds.METHOCEL products impart worka-bility, shrink and crack resistance,slip, and adhesion in tape-joint com-pounds. Water retention propertiesincrease open times and help main-tain a wet edge.

Cement-based tile mortars.METHOCEL cellulose ethers providewater retention and workability toPortland cement-based ceramic tilemortars and grouts. They alsoimprove adhesion, reduce skinning,and increase open time.

Masonry mortars. Used as perfor-mance additives in masonry mortars,METHOCEL products extend boardlife and improve workability. METHOCEL also contributes to airentrainment, often reducing the needfor other additives for this purpose.

Gypsum adhesives and gypsum andcement hand and spray plasters.METHOCEL cellulose ethers impartworkability, pumpability, and consis-tency to adhesives and hand andspray plasters. They also providewater retention and anti-sag properties.

Wall and ceiling textures.METHOCEL products impart pumpa-bility, adhesion, workability, and waterretention in wall and ceiling texturiz-ing products.

Cement plaster and stucco.METHOCEL cellulose ethers providewater retention for proper curing,improved workability, and pumpability.

FoodsBakery products. Thermal gelationaids in gas retention during baking,increasing baked volumes andimproving texture. METHOCELalso provides a more moist texture,increased shelf life, improved emulsi-fication of batters, and betterfreeze/thaw stability.

Pie and pastry fillings. Thermalgelation reduces boil-over during baking and inhibits moisture migra-tion from fillings to crusts duringfreezing. METHOCEL also improvesfreeze/thaw stability.

Frozen desserts. METHOCELproducts modify ice-crystal size togive smoother textures and improveemulsion stability. Increased airentrainment improves over-run.

Whipped toppings. METHOCELproducts improve whipping propertiesfor better body and appearance.Improved emulsion stability preventssyneresis and extends open times.METHOCEL inhibits phase separa-tion in frozen toppings, even throughrepeated freeze/thaw cycles.

Structured and extruded foods.Low concentrations of METHOCELgive optimum binding strength inmatrix systems. Due to moistureretention and oil insolubility proper-ties, fried foods are more moist, less greasy. Thermal gelation givesincreased control over texture and“bite”. Increased lubricity aids in processing.

Frying batters. In addition to formingan oil-insoluble barrier to block oilabsorption and moisture loss duringfrying, METHOCEL products improveadhesion of batters to meat and veg-etable substrates. As a result, blow-off of batters is reduced and the lifeof frying oil is extended.

Salad dressings and sauces. Betterstability for oil-in-water emulsionsextends the shelf life of products con-taining METHOCEL. Solids stay insuspension longer and body andpouring characteristics are controlled.

Gelled FuelsFuel thickeners. METHOCEL cellu-lose ethers are used as thickeners for gelled alcohol used in charcoallighters, restaurant candles, andcanned-fuel products.

Household productsCleaners and detergents. Use of METHOCEL provides viscositycontrol, cling, foaming, soil anti-redeposition, and emulsion stabilization to household cleaners and detergents.

PaintsLatex paints. METHOCEL is used as a thickener, protective colloid, and pigment-suspension aid in latexpaints. It provides high enzyme resis-tance which helps stabilize viscosity.Film-forming properties contribute tobetter paint film quality with fewerpinholes. The product uniformityoffered by METHOCEL celluloseethers can mean lower quality controlcosts and more predictable perfor-mance for paints. Their use alsoimproves wet-edge retention. Theyoffer flexibility and ease of incorporation.

Paint RemoversScrape-off and flush-off paintremovers. The unique combinationof organic and water solubility offeredby METHOCEL products makes themideal thickeners for scrape-off andflush-off paint removers (both methyl-ene chloride and alternative paintstrippers). They provide the thickeningand cling needed to retain the paintremover on vertical or inclined sur-faces, yet permit the softened paint to be rinsed off easily with water.

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Paper ProductsGrease-proof coatings, adhesives,release coatings, and surface sizings. Grease and oil barrier prop-erties in conjunction with film-formingcapabilities make METHOCEL valu-able in a variety of paper coatingsand sizings. The excellent film prop-erties (high tensile strength and goodelongation) offered by METHOCELplay key roles in these applications.

Personal Care ProductsShampoos. METHOCEL celluloseether is widely used as a thickener inshampoos. Because the thickeningperformance of METHOCEL doesn’tdepend on a high surfactant level, it’sthe thickener of choice for shampoosdesigned for dry and normal hair.METHOCEL also helps stabilizefoams, so shampoos have betterlather characteristics.

Creams and lotions. METHOCELcan contribute film-forming and sec-ondary-thickening properties whichimprove after-feel and other sensorycharacteristics in creams and lotions.

PharmaceuticalsTablet coatings. METHOCEL cellu-lose ethers form strong films withgood adhesion. They provide taste-masking films and act as excellentbarriers for water-sensitive drugs orcomponents. Coatings of METHOCELalso increase compressive strengthand reduce friability.

Granulation. Used at low concentra-tions as binders in the granulationprocess, METHOCEL products pro-duce hard tablets with low friability,yet don’t negatively affect tablet disin-tegration. METHOCEL allows thereduction of compression force, animportant factor in extending the lifeof tooling and equipment.

Controlled release. METHOCELcellulose ether can be used for controlled-release pharmaceuticalsusing two different methods. It isused in hydrophilic-matrix tablets orcapsules as described in a separatebulletin on sustained release. In addi-tion, METHOCEL is used in diffusioncontrol films comprising of METHOCELcellulose ethers and ETHOCEL* ethyl-cellulose resins. The water-solubleMETHOCEL dissolves out of the film,leaving the water-insoluble ETHOCELethylcellulose. Drug diffusion and filmporosity are controlled by the amountof METHOCEL used.

Water-soluble thermoplastics.METHOCEL cellulose ethers can beheated and mixed with a plasticizerfor extrusion or molding into awide range of physical forms. Thisprocess is used to produce single-unit matrix tablets; multi-particledelivery, such as extruded beads orchips; transdermal patches; supposi-tories; or liquid-filled hard-shellcapsules.

Liquid preparations. METHOCELproducts are used in oral and topicalliquid pharmaceuticals because theyare excellent thickeners, improveemulsion stability, suspend solids,lubricate, and retain moisture. Theprotective colloid action and emulsify-ing properties of METHOCEL alsobenefit many liquid formulations.

PrintingPrinting inks. METHOCEL celluloseethers are used as thickeners andsuspending agents for water-basedinks.

TextilesTextile printing pastes. Used asemulsion stabilizers in textile printingpastes, METHOCEL cellulose ethershelp keep inks from wicking into fabrics.

Fabric sizings. METHOCEL helpshold fibers together, which strength-ens fabrics during manufacturingprocesses. The lubricity of METHOCELhelps cut friction, permitting fasterequipment speeds.

Temporary adhesives. Excellentwet-tack and quick-set propertiesmake METHOCEL an ideal temporaryfabric adhesive.

9* Trademark of The Dow Chemical Company

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Chemical Inventory

METHOCEL products, methylcellu-lose and hydroxypropyl methylcellu-lose, comply with all applicable rulesand orders under Toxic SubstancesControl Act PL94-469. The ChemicalAbstracts Services Registry No.(CAS) is 9004-67-5 for methylcellu-lose and 9904-65-3 for hydroxypropylmethylcellulose.

METHOCEL products have also beenreported for the following inventories:

European Inventory of ExistingChemical Substances (EINECS)

Australia Inventory of ChemicalSubstances (AICS)

Ministry of International Trade andIndustry Inventory (MITI, theJapanese inventory)

Canadian Domestics Substances List(DSL)

Many countries are in the midst ofcreating new chemical inventories.Please contact your Dow Represen-tative for the status of METHOCELproducts for countries not listedabove.

Pharmaceuticals

Premium grades of METHOCEL A,METHOCEL E, METHOCEL F, andMETHOCEL K products are used forpharmaceutical and topical applica-tions. Premium grades of METHOCELproducts meet the specifications ofthe United States Pharmacopeia(USP XXIII), European Pharmacopeia(EP) and Japanese Pharmacopeia(JP) and are listed as methylcelluloseand hydroxypropyl methylcellulose. In addition, methylcellulose (METHOCEL A products) is GenerallyRecognized As Safe (GRAS) by theFood and Drug Administration.

To support new drug applications inthe United States, masters files forthese products are on file at theBureau of Drugs of the Food andDrug Administration. Permission toopen the master file can be obtainedby writing:

The Dow Chemical CompanyProduct Safety and Compliance2030 Dow CenterMidland, MI 48674

A bibliography of pharmaceutical andmedical references is available from:

The Dow Chemical CompanyChemicals and PerformanceProducts Department2020 Dow CenterMidland, MI 48674

Foods

METHOCEL Premium celluloseethers have long been used in thefood industry. Premium gradeMETHOCEL products are approvedwithin the Food Chemicals Codexand are listed as methylcellulose andhydroxypropyl methylcellulose.

In the U.S., methylcellulose isapproved as a multiple purposeGRAS food substance according to21CFR 182.1480. It is also allowedfor use in meat products according to 9CFR 318.7 and 9CFR 381.147.Hydroxypropyl methylcellulose isapproved for direct food use by theFDA under 21CFR 172.874. It is alsoapproved by the USDA as an emulsi-fing agent, binder, thickener, and sta-bilizer and is listed in the Standardsand Labeling Policy Book publishedby the USDA. Because they areapproved for direct food use,METHOCEL products can also beused as packaging components andin indirect food applications.

In the European Union, PremiumMETHOCEL products are approvedfor use within the European Directive95/2/EC. Hydroxypropyl methylcellu-lose and methylcellulose are includedin Annex I of this Directive.

When labeling these food ingredients,one can use either their proper chem-ical names or their common names.Therefore, one could use "methylcel-lulose" or "modified vegetable gum"for METHOCEL A products. ForMETHOCEL E, F, or K products, onecould use "hydroxypropyl methylcellu-lose" or "carbohydrate gum."METHOCEL products are also certified as kosher for year-round and Passover use by the Union ofOrthodox Jewish Congregations ofAmerica.

Pesticide UseUnder 40CFR 180.1001, certain inertingredients used in pesticide formula-tions are exempt from the require-ments of a tolerance. Methylcelluloseand hydroxypropyl methylcellulosemay be used in formulations appliedto growing crops or raw agriculturalcommodities after harvest. BothStandard and Premium gradeMETHOCEL cellulose ether productsare appropriate.

10

Regulated Uses

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METHOCEL cellulose ether productsare carbohydrate polymers which dissolve in cold water (and in someinstances in certain organic solvents)by swelling and subsequent hydra-tion. There is no sharp solubility limitsuch as occurs in the dissolution ofionizing salts. The concentration ofMETHOCEL in solution is usually limited by the viscosity that a manu-facturer is equipped to handle. It alsodepends on the viscosity and chemi-cal type of METHOCEL product used.Solutions of low-viscosity productscan be made at 10 to 15% concen-tration. High-viscosity products find anormal limit at 2 to 3% concentration.

The form of METHOCEL celluloseether product chosen (powder or surface-treated powder, or granules)influences the techniques used tomake solutions. Surface-treated andgranular products can be addeddirectly to aqueous systems. Theydisperse readily with mild agitationand dissolve (build viscosity) graduallyunder neutral conditions. The dissolu-tion rate of surface-treated productscan be increased by adjusting to analkaline pH after dispersing the powder in water. Although untreatedMETHOCEL powders are soluble incold water, they must first be thor-oughly dispersed in the water toprevent lumping.

Working With Surface-treated Dispersible Powders

In many applications, the combinationof easy dispersion in cold water andrapid hydration (viscosity build) isdesirable. Surface-treated METHOCELpowders are chemically treated sothat they become temporarily insolu-ble in cold water. This allows theMETHOCEL product to be addedto a formulation and dispersed at relatively low shear without any significant viscosity increase initially.

The “time delay” of the hydration orviscosity build is a function of thelevel of surface treatment as well astemperature, pH of the system, andconcentration of the METHOCELproduct. Normally, the concentrationof METHOCEL in the system doesnot become a factor until the concen-tration exceeds 5% by weight (rela-tive to water in the system). At higherconcentrations, the time of hydration(referred to as delay time) is reduced.The delay time is generally reducedas temperature is raised. Figure 2shows a typical delay time as a func-tion of pH, evaluated at room temper-ature.

In many cases it is desirable to “trig-ger” viscosity build immediately fol-lowing dispersion. Aqueous slurriescan be held for 45 minutes and stillremain usable in neutral systems. A trigger can conveniently be used by adding a small amount of a base,such as ammonium hydroxide, sodiumbicarbonate, etc. If METHOCELis dispersed in neutral water (pHapproximately 7), there is adequatetime for thorough dispersion. Additionof base to raise the pH to approxi-mately 9 causes the hydration to becompleted in just a few minutes.

For best results and to achieve maxi-mum hydration, surface-treated pow-ders should be added with good agitation to a neutral pH system. The system should be agitated thor-oughly for a few minutes followed byan adjustment of pH to 8.5 to 9.0 withcontinued agitation until full viscosityis reached (usually 10 to 30 minutes).Once the pH has been shifted to thealkaline side (pH 8.5 to 9.0), allowingfull and rapid solubilization of the sur-face-treated product, solutions arestable over the pH range of 3 to 11.

The addition of a slurry to an alkalinepigment grind or filler dispersion orthe addition of a slurry to a basic pig-ment-latex formulation provides rapidsolubilization and uniform viscositydevelopment. The addition of dry,alkaline pigments or fillers to a slurryon high-speed or low-speed mixingequipment also results in rapid solu-bilization and viscosity development.

CAUTION: Attempts to adjust the pHof high-concentration slurries may lead to excessively high viscosity sothat they cannot be pumped or poured.The pH adjustment should be madeonly after a slurry is diluted to the concentration at which it will be used.

11

How To Prepare Aqueous Solutions of METHOCEL

Figure 2: Typical Hydration Delay Time of Surface-treated METHOCELProducts as a Function of pH

0 2 4 6 8 10 pH

1000.0

100.0

10.0

1.0

0.1

Hyd

ratio

n T

ime,

min

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Dispersion Technique

1. Add the surface-treated METHOCELpowder to the water.Begin agitation.

2. Continue agitationand add sufficientammonium hydroxide,sodium bicarbonate, orother alkaline material(e.g., pigment grind) tothe dispersion to obtaina pH of 8.5 to 9.0. Thiswill result in rapid viscosity develop-ment. Continue agitation until suffi-cient hydration has been achieved.

Working With Untreated Powders

Although METHOCEL powders aresoluble in cold water, they must firstbe thoroughly dispersed in the waterto prevent lumping. In some applica-tions, dispersion can be accom-plished at ambient temperatures or incold water by using an eductor funnelor high-shear mixer. However, ifuntreated powders are added directlyto cold water without sufficient agita-tion, a lumpy solution may result.Lumping results from incomplete wet-ting of the individual powder particles.Only part of the powder dissolves, agelatinous membrane which shieldsthe remaining powder from completehydration. Several dispersion tech-niques are commonly used and aredescribed below. Each has advan-tages in certain applications.

Dispersion in Hot Water

Often called the “hot/cold” technique,this method takes advantage of theinsolubility of METHOCEL celluloseethers in hot water. The powder isfirst dispersed by mixing thoroughlywith 1/5 to 1/3 of the total requiredvolume of water that has been heatedto above 90°C (194°F). Mixing contin-ues until all particles are thoroughlywetted.

For complete solubilization, theremainder of the water is then addedas cold water or ice to lower the tem-perature of the dispersion. Once thedispersion reaches the temperatureat which that particular METHOCELproduct becomes water soluble, thepowder begins to hydrate and viscos-ity increases.

In some applications, it may be desirable to heat the entire volume of water, disperse the METHOCELpowder, then cool the mixture whileagitating until hydration is complete.It is very important, however, to haveadequate cooling after wetting withhot water to ensure complete hydra-tion and viscosity development.

For improved clarity and reproduciblecontrol of viscosity, solutions ofMETHOCEL A cellulose ether products(methylcellulose) should be cooled to

0 to 5°C (32 to 41°F) for 20 to 40minutes. In general, solutions ofMETHOCEL E, METHOCEL F,METHOCEL J, and METHOCEL Kbrand cellulose ethers (hydroxypropylmethylcellulose) require cooling to 20to 25°C (68 to 77°F) or below.

Because complete hydration dependson adequate cooling, METHOCEL E,F, J, and K brand products are fre-quently used in applications wherecold water is not available. Figure 3illustrates the effects of cooling hotslurries of METHOCEL A andMETHOCEL K products. This figureshows that a slurry of METHOCEL Kbrand cellulose ether requires muchless cooling for hydration than a slur-ry of METHOCEL A cellulose ether.Slurries of METHOCEL E, F, and Jbrand products also require less coolingthan METHOCEL A brand products.

12

Figure 3: Viscosity Development of METHOCEL A andMETHOCEL K Brand Products Slurried at 2% in Hot Water

100 80 60 40 20 0

Temperature, °C

10,000

1,000

100

10

Vis

cosi

ty, m

Pa.

s

Viscosity on InitialCooling ofMETHOCEL A Premium

Viscosity on InitialCooling ofMETHOCEL K Premium

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Dispersion Technique

1. Heat approximately1/3 the required vol-ume of water to atleast 194°F (90°C).

2. Add the METHOCELpowder to the heatedwater with agitation.

3. Agitate the mixtureuntil the particles arethoroughly wetted andevenly dispersed.

4. For complete solubi-lization, add theremainder of the wateras cold water or ice tolower the temperature

of the dispersion. Once the disper-sion reaches the temperature atwhich that particular METHOCELproduct becomes water soluble, thepowder begins to hydrate and viscos-ity increases. See page 12 for coolingtimes and temperatures for specificMETHOCEL products.

5. Continue agitationfor at least 30 min-utes after the propertemperature isreached. Your solu-tion of METHOCELcellulose ether isnow ready to use.

Dispersion by Dry-Blending

Dry-blending involves mixingMETHOCEL powder with other dryingredients before adding the watercomponent. Dry-blending separatesthe particles of METHOCEL celluloseethers to allow thorough wet-out andcomplete hydration when water isadded. The minimum ratio of otherdry, powdered ingredients toMETHOCEL powder varies from 7:1to 3:1.

Dispersion Technique

1. Combine METHOCELpowder with other dry-powder ingredients. Thesuggested ratio of otherdry-powder ingredientsto METHOCEL is 7:1;

however, the ratio may vary from 7:1to 3:1.

2. Thoroughly blend thedry components.

3. Add the dry mix tothe water with agitation.The rate of hydrationwill depend upon boththe relative particlesizes and the rate of

agitation during and after addition of the mixture to the water.

4. Agitate until theMETHOCEL powderhas completely hydratedand the solution is con-sistently smooth. Yoursolution of METHOCELcellulose ether is nowready for further processing.

Dispersion in Concentrated SaltSolutions

Both untreated and surface-treatedMETHOCEL cellulose ethers can bedispersed in concentrated salt solu-tions. Dissolution occurs when thebrine is diluted with cold water.

13

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Solubility in Nonaqueous Solvents

The solubility of METHOCEL celluloseethers in nonaqueous media variesaccording to the nature and quantity ofsubstituent groups on the anhydroglu-cose chain. When using a water-misci-ble, organic solvent, such as an alcoholor glycol, use a ratio of at least 5 to 8parts of solvent to 1 part METHOCEL.

Dispersion in Nonsolvent Media

Untreated METHOCEL celluloseethers may also be dispersed in non-solvent media such as vegetable oil,propylene glycol, polyethylene glycol,glycerine, corn syrup, and high-fructosecorn syrup. A ratio of 5 to 8 parts non-solvent to 1 part METHOCEL is rec-ommended to obtain a fluid slurry. Thedispersion of METHOCEL in nonsol-vent medium may then be added tocold water, or the cold water may beadded to the dispersion.

Dispersion Technique

1. Add the METHOCELcellulose ether to the nonsolvent. A ratio of 5-8parts nonsolvent to 1 partMETHOCEL is recom-mended to obtain a liquidslurry.

2. Agitate the mixture andMETHOCEL powder untilthe particles of METHOCELcellulose ether are evenlydispersed.

3. The dispersion ofMETHOCEL in non-solvent medium may beadded to cold water, orthe cold water may beadded to the dispersion.

4. Continue mixing untilthe METHOCEL powderis completely hydratedand the solution issmooth. You can nowadd the remainingingredients in your formulation.

14

How To Prepare Solutions of METHOCEL in NonaqueousSolvents and Nonsolvent Media

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METHOCEL cellulose ether productsare white to slightly off-white powderswhich are essentially odorless andtasteless. The apparent density of thepowders ranges from 0.25 to 0.70g/cm3 (250-700 kg/m3).

Moisture Sorption

METHOCEL products sealed in theiroriginal shipping containers absorblittle to no atmospheric moisture.Once a container is opened, howev-er, there is pick-up of moisture fromthe air. When “exposed” METHOCELcellulose ether is weighed, a portionof the total weight, therefore, may bewater. Such weight must be correctedfor moisture content to ensure thatthe proper weight of METHOCEL isused to give the desired viscosity.

To minimize moisture pick-up,opened bags should be tightlyresealed. The moisture-sorption rate of METHOCEL K brand products is somewhat greater thanfor METHOCEL A brand products.However, the moisture-sorption ratesare about the same within a singlechemical type. Typical moisture sorption is shown in Figure 4.

Resistance to Microorganisms

An important property of METHOCELcellulose ether products is their highresistance to attack by microorgan-isms. METHOCEL products withhigher degrees of substitution areespecially resistant to enzymes. The fact that virtually all METHOCELmethylcellulose and METHOCELhydroxypropyl methylcellulose etherspass through the intestinal tractessentially unchanged attests to thestability of these products to a widerange of biochemical and enzymaticsystems. Shelf-life in paints and otherlatex-based coatings, and stability of

solutions and other products contain-ing METHOCEL cellulose ether, canbe greatly increased by this resis-tance to microorganisms.

As the cellulose is modified by substitution with various radicals,such as alkyl and hydroxyalkylgroups, resistance to microbial attack increases. Several researchershave reported that the degree of sub-stitution (D.S.) of water-soluble cellu-lose derivatives was a primary factor,with a threshold D.S. value of 1.0required for protection.†

Because METHOCEL cellulose etherproducts have excellent uniformity ofsubstitution, with a D.S. much higherthan 1.0, they possess excellentresistance to microbial attack.

15

Properties of METHOCEL in Powder Form

Figure 4: Equilibrium Moisture Contentvs Percent Relative Humidity, 25°C

0 10 20 30 40 50 60 70 80 90 100

% Relative humidity, mean average value,+95% probability

80

70

60

50

40

30

20

10

0

%H

2O, 2

5°C

†H.S. Levinson and E.T. Reese, J. Gen. Physiol. 33, No. 601 (1950).E.T. Reese, R.G.H. Siu, and H.G. Levinson, J. Bacteriology 59, No. 485 (1950).E.T. Reese, Ind. Eng. Chem. 49, No. 104 (1957).

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Some of the general solution proper-ties of METHOCEL cellulose etherproducts are listed in Table 6.

Rheology of Solutions ofMETHOCEL Cellulose Ether

The rheology of solutions of METHOCEL plays an important rolein many practical applications wherethe modification of flow behavior isessential (for example, paints, cos-metics, food products, building prod-ucts). A Newtonian fluid is one whoseviscosity is independent of shear rate(or velocity gradient of flow). In actualpractice many systems exhibit non-Newtonian flow behavior whereapparent viscosity may decrease(pseudoplastic) or increase (dilatant)with increasing rate of shear.

Rheology of an aqueous solution ofMETHOCEL is affected by its molec-ular weight, concentration, tempera-ture, and by the presence of othersolutes. In general, aqueous solu-tions of METHOCEL exhibit pseudo-plastic flow behavior. Pseudoplasticityincreases with increasing molecularweight or concentration. However, atvery low shear rates, all solutions ofMETHOCEL cellulose ether appear tobe Newtonian and the shear ratebelow which the solution becomesNewtonian increases with decreasingmolecular weight or concentration.Figures 5 and 6 illustrate this behav-ior (the numbers on curves indicateviscosity types).

16

Properties of Solutions of METHOCEL

Table 6: General Solution Properties

Specific gravity, 4°C, all types1% solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.00125% solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.011710% solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0245

Refractive index, 2% solutions, all types1.336

Partial specific volume4,000 mPa·s METHOCEL A . . . . . . . . . . . . . . . . . 0.725 cm3/g (0.087 gal/lb)4,000 mPa·s METHOCEL E . . . . . . . . . . . . . . . . . 0.767 cm3/g (0.092 gal/lb)4,000 mPa·s METHOCEL F . . . . . . . . . . . . . . . . . 0.734 cm3/g (0.087 gal/lb)5,000 mPa·s METHOCEL J . . . . . . . . . . . . . . . . . 0.725 cm3/g (0.087 gal/lb)4,000 mPa·s METHOCEL K . . . . . . . . . . . . . . . . . 0.717 cm3/g (0.086 gal/lb)15,000 mPa·s METHOCEL K . . . . . . . . . . . . . . . . 0.724 cm3/g (0.087 gal/lb)

Freezing point, 2% solutions, all types0.0°C at 2% concentration

Surface tension, 25°C, 0.05% concentrationWater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72–74 x 10-3 Newton/meter (72–74 dynes/cm)Methylcellulose. . . . . . . . . . . . . . . . . . . . . . . . . . . 53–59 x 10-3 Newton/meter (53–59 dynes/cm)Hydroxypropyl methylcellulose . . . . . . . . . . . . . . . 43–55 x 10-3 Newton/meter (43–55 dynes/cm)

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17

Figure 5: Apparent Viscosity vs. Shear Rate, 2% Aqueous Solutions, 20°C

0.1 1 10 100 1,000

Shear Rate, s-1

10,000

1,000

100

10

App

aren

t Vis

cosi

ty, m

Pa.

s

4,000

1,500

400

100

25

Figure 6: Apparent Viscosity vs. Shear Rate, for Aqueous Solutions of 4,000mPa.s METHOCEL at Various Concentrations

0.1 1 10 100 1,000

Shear Rate, s-1

10,000

1,000

100

10

App

aren

t Vis

cosi

ty, m

Pa.

s @

20°

C

2%

1.5%

1%

0.5%

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Molecular Weight/Viscosity Relationships

The apparent viscosity of aqueoussolutions of METHOCEL is proportionalto the molecular weight or chainlength of the specific METHOCELproduct used. Commercial designa-tions of METHOCEL products arebased on viscosity values determinedin water at 20°C, with a concentrationof 2% METHOCEL. The measure-ment methods used are described inthe current ASTM monographs D1347and D2363. The correlation betweenthe number average molecular weight(Mn) and the commercial viscositydesignation for METHOCEL A cellu-lose ethers is shown in Figure 7.

Table 7 provides further informationregarding the correlation of number average molecular weight with thecommercial viscosity designation.Intrinsic viscosity is the limiting quotient of the specific viscositydivided by the concentration asinfinite dilution is approached (as the concentration approaches zero).The number average molecularweight (Mn) is calculated from the limiting osmotic pressure of thesolvent as the concentration ofthe solute approaches zero. Theweight average molecular weight(Mw) will be 3 to 10 times the Mn.

Effect of Concentration on Viscosity

Most formulations require apredetermined product viscosity ofMETHOCEL cellulose ether. Figure 8shows how the concentration ofMETHOCEL products of varying viscosity affects the aqueous solutionviscosity at 20°C. The measurementswere made using an Ubbelohde viscometer (ASTM D2363). Data forboth low and high molecular weightMETHOCEL products are shown andrepresent the average material foundwithin a viscosity specification.

18

Molecular Weight

Figure 7: Molecular Weight/Viscosity Correlation, 20°C

1,000 10,000 100,000

100,000

10,000

1,000

100

10

0

Vis

cosi

ty o

f an

Aqu

eous

Sol

utio

n, m

Pa.

s @

20°

C

Mw

Mn

Table 7: Viscosity of Methyl Cellulose of Various Molecular Weights

5 1.2 53 10,00010 1.4 70 13,00040 2.0 110 20,000

100 2.6 140 26,000400 3.9 220 41,000

1,500 5.7 340 63,0004,000 7.5 460 86,0008,000 9.3 580 110,000

15,000 11.0 650 120,00019,000 12.0 750 140,00040,000 15.0 950 180,00075,000 18.4 1,160 220,000

Intrinsic Number average Number averageViscosity grade viscosity degree of molecular

2%, 20°C, mPa·s (h), dL/g polymerization weight (Mn)

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This graph is plotted on an 8th rootscale, not a logarithmic scale. The8th root of the viscosity is a roughlylinear function of the concentration.

The equation which expresses theillustrated approximate relationshipbetween solution viscosity and poly-mer concentration is h1/8 = (C·a) + 1,where h is the solution viscosity inmillipascal-seconds, C is the polymerconcentration in solution (expressedin percent), and a is a constant spe-cific to the molecular weight. Thevalue of a may be calculated by substitution and may then be used to calculate the approximate viscosity at the desired concentration.

For example, for a 4,000 mPa·s product, (4,000)1/8 = (C·a) + 1. Solving for a yields a value of 0.910.For a 1500 mPa·s product, (1500)1/8= (C·a) + 1. Solving for a yields avalue of 0.747. Having calculated afor a particular METHOCEL product,this value can be used to calculate viscosity at other concentrations.

To find the line for any intermediategrade, locate the desired 2% viscosityabove 2% on the abscissa and drawa straight line to the point of origin.

Blending for Intermediate Viscosity

METHOCEL products of the samesubstitution type but of different viscosity grades can be blended to obtain an intermediate viscositygrade. Figure 9 is a blending chartthat can be used for this purpose.

To use the chart, the points corre-sponding to the viscosities of the two starting materials are selected on the two vertical scales (A and B)and connected with a line. The point corresponding to the desired final viscosity is then located on one of the vertical scales and a horizontalline drawn from it to the first line isdrawn.

19

Figure 8: Viscosity/Concentration Relationships

0 1 2 3 4 5 6 7

% METHOCEL Cellulose Ether

100,000

75,000

50,000

Vis

cosi

ty, m

Pa.

s @

20°

C

15,000

10,000

4,000

1,500

1,000

400250

100

50

251510

1

15

5

500

100

400

4,000

15,000

40,000

100,000

1,500

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A vertical line drawn from this inter-section to the bottom scale will revealthe percent of Scale B material need-ed to make up the blend.

This relationship may be expressedmathematically as: hB

1/8 = x1h11/8 +

x2h21/8 , where x1 and x2 are the

weight fractions of components oneand two, respectively.

The example on the chart shows that60% of 15,000 mPa·s material and40% of the 400 mPa·s material areneeded to make a blend having a viscosity of 4,000 mPa·s.

Effect of pH on Viscosity

Because METHOCEL products arenonionic, the viscosities of their solu-tions are generally stable over awider pH range than are the viscosi-ties of gums that are ionic in nature.Outside the range of pH 3 to 11, how-ever, there may be a gradual loss ofviscosity at higher temperatures orafter long periods of standing, espe-cially with high-viscosity solutions.Solutions of METHOCEL celluloseethers in acids or in strong causticsolutions will decrease in viscosity.This factor should be consideredwhen determining the shelf life ofproducts.

Effect of Additives on Viscosity

In the preparation of formulations, vis-cosities may occasionally result whichare considerably higher than expect-ed. This phenomenon can be causedby the interaction of METHOCEL withone or more of the formula ingredi-ents. As a result, it may be possibleto use less thickener and still haveadequate viscosity.

This effect usually passes through amaximum that is dependent on theconcentration of the interacting mate-rials and on the presence of otheringredients such as pigments, latexparticles, or preservatives. In systems

having lower concentrations of additives (~1%), METHOCEL A orMETHOCEL F products are frequentlysuitable. In systems where the concentration of additives is ratherhigh (~10%), the more highly substi-tuted products such as METHOCELE, J, or K products may be morecompatible.

Effect of Freezing on Solutions

Solutions of METHOCEL celluloseether products do not undergo sepa-ration into phases upon freezing.There is no separation of fluid layers(syneresis) or formation of insoluble

precipitates or haze. This lack ofphase separation on freezing is par-ticularly important in frozen fooditems. As solutions of METHOCELcellulose ether products are cooled,solubilization increases, as evidencedby increasing viscosity and improvedclarity of solutions. When the solu-tions freeze, part of the water is heldin the latent super-cooled state anddoes not freeze. The heat normallyreleased on freezing (heat of fusion)is decreased by the amount of thesuper cooling.

20

Figure 9: Blending Chart

0 20 40 60 80 100

% of Scale B Material in Blend

100,000

Sca

le A

V

isco

sity

, mP

a.s

@ 2

0°C

10,000

1,000

100

10

400

100,000

10,000

1,000

100

10

Sca

le B

V

isco

sity

, mP

a.s

@ 2

0°C4,000

15,000

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Defoamers for AqueousSolutions

The foaming of solutions of METHOCELcellulose ether is easily controlled byusing foam stabilizers and defoamers.Table 8 lists several defoamers whichhave proved effective. However,other commercial defoamers maywork equally well and all productsshould be tested for performance.

The concentration required fordefoaming with any of the listedagents is 25 to 1000 ppm, based onsolution weights. Defoamer concen-trations should be kept to the minimumrequired because these materials aregenerally low in water solubility. Thechoice of a defoamer depends on thetype of surfactant, latex, and otheringredients in the system. For defoam-ing complex systems, consultationwith the supplier of defoamers is suggested.

Antifoam agents are extremely efficientsurface-active compositions which dis-place other surface-active substancesat the air/water interface. Their use,therefore, might interfere with the per-formance of METHOCEL products inapplications where the mechanicalproperties of solution-surface films iscritical.

Preservatives for Aqueous Solutions

METHOCEL cellulose ethers normallydo not require preservatives. Theyare not, however, antimicrobialagents. If contamination occurs,microorganism growth will not beinhibited.

To preserve solutions of METHOCEL,addition of 0.05 to 0.15% ofDOWICIDE* A antimicrobial orDOWICIL* 75 preservative is suggested. More information onthese products is available uponrequest. For regulated uses, youshould use the appropriate permittedpreservative.

Compatibility of Aqueous Solutions

The methylcellulose molecule is non-ionic and is not precipitated as aninsoluble salt by multivalent metalions. However, METHOCEL celluloseethers can be salted out of solutionwhen the concentration of elec-trolytes or other dissolved materialsexceeds certain limits. This is causedby competition of the electrolytes forwater and results in reduced hydra-tion of the cellulose ether.

Because of the difference in theamounts of organic substitution,METHOCEL E, F, J, K, and 310-Series brand hydroxypropyl methyl-cellulose products generally exhibit a higher tolerance for salts in solutionthan METHOCEL A brand methylcel-lulose products. There is only slightvariation in electrolyte toleranceamong the various METHOCELhydroxypropyl methylcelluloseproducts.

Water-insoluble materials such aspigments, fillers, etc., will notadversely affect METHOCEL celluloseethers. Actually, solutions of METHOCELoften serve as excellent dispersingmedia for such materials. Otherwater-soluble substances such asstarches, glues, and resins may or maynot be compatible with METHOCEL.Tests should be run on these materialsto determine compatibility. BecauseMETHOCEL cellulose ether productsare not soluble in concentrated saltsolutions, these media can be usedas nonsolvent dispersing media fornon-surface-treated METHOCELproducts. Subsequent dilutionreduces the salt concentration to alevel that allows dissolution of theMETHOCEL product.

21* Trademark of The Dow Chemical Company

Table 8: Defoamers for Aqueous Solutions

General use

Paper sizings

Latex paints

Foods

Foamicide 581 BNopco KFS

Antifoam A, B, C, FLauryl alcoholPolyglycol P1200Tri-n-Butyl phosphate

Colloids 770Foamicide 581B

Foammaster 111, VF, G, R

Nopco NXZ, NDW

Colloids 643, 581BHodag PV-22, PV-108Drew 475

Dow Corning FG-10Foammaster 6-FG

Colloids, Inc.Henkel, Process Chemical DivisionNopco Chemical CompanyDow Corning CorporationDow Corning CorporationThe Dow Chemical CompanyDow Corning Corporation

Colloids, Inc.Colloids, Inc.

Henkel, Process Chemical DivisionNopco Chemical CompanyHenkel, Process Chemical DivisionNopco Chemical CompanyColloids, Inc.Hodag Chemical CompanyDrew Chemical, Division ofAshland Chemical

Dow Corning CorporationHenkel, Process Chemical Division

Application Defoamer Producer

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METHOCEL cellulose ethers possessunique solubility properties in aque-ous media. These products are insol-uble in water that has been heatedabove a particular temperature.Below those temperatures the solu-tion and solubility of the METHOCELcellulose ether products increase asthe temperature is lowered. Aqueoussolutions of METHOCEL celluloseethers will gel when heated to tem-peratures that are specific for eachtype. The gels are completelyreversible and the solutions liquefyupon cooling. This unique bulk thermal-gelation property provesvaluable, compared to that of othernatural and synthetic gums, in a wide variety of applications.

Bulk thermal gelation of aqueoussolutions of METHOCEL is thought tobe primarily caused by the hydropho-bic interaction between moleculescontaining methoxyl groups. In asolution state at lower temperatures,molecules are hydrated and there islittle polymer-to-polymer interactionother than simple entanglement.Figure 10 shows the viscosity of atypical solution as it is heated to itsgel temperature, then cooled to theoriginal temperature.

As the temperature of the solution isincreased, the cellulosic polymersgradually lose their water of hydrationand viscosity decreases. When thegel point is reached, sufficient dehy-dration of the polymer occurs tocause a polymer-to-polymer associa-tion, and the solution begins to gel.

Gel strength continues to build as the temperature is held above the gel point.

When the solution is cooled, the geleffect begins to reverse and viscositydrops rapidly. Finally, the viscosity ofthe cooling solution merges with theoriginal heating curve and increasesas the temperature decreases. Once the solution has cooled, the vis-cosity is the same as it was originally.Thus the thermal gelation process isreversible and can be repeated ifdesired.

22

Thermal Gelation in Aqueous Media

Figure 10: Gelation of 2.0% Aqueous Solution of METHOCEL A100 Methyl Cellulose, Heating Rate0.25˚C/min

0 10 20 30 40 50 60 70Temperature, °C

Vis

cosi

ty, m

Pa.

s

200

160

120

80

40

0

Gelled

Incipient GelationTemperature

Cooling

Con

ditio

ned

Hea

ting

Heating

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Controlling Gel Temperature

The specific temperature at whichbulk thermal gelation occurs (theincipient gelation temperature or IGT)and the firmness of the gel are gov-erned by the nature and quantity ofthe substituent groups attached tothe anhydroglucose ring and, thus,vary with each type of cellulose ether.The molecular weight of the particularMETHOCEL product selected has little effect on the gel temperature.However, increasing the concentra-tion of the solution lowers the geltemperature as shown in Figure 11.

Within the range of viscosity availablein the “A” type, the low-viscosity prod-ucts will have gel points substantiallyhigher than those of the high-viscosityproducts. The spread between highand low viscosity for the otherMETHOCEL cellulose ether types is relatively narrow.

The Effects of Heating Rate andAgitation on Gelation

Accurate measurement of gelationtemperature requires care because it is a function of the rate of heatingand the rate of shear. Both a highrate of shear and a fast heating rate result in an apparently high gel temperature.

Agitation also affects the strength ofthe gel. Continued rapid agitationduring gelation may break down thegel structure and alter both the tex-ture and strength of the gel. For max-imum development of gel strength,heat the solution well above the gela-tion temperature under quiescentconditions.

Gel Strength and Texture

The texture and strength of gelsproduced by heating solutions ofMETHOCEL cellulose ethers varieswith the product type, viscosity grade,

and concentration of METHOCELused. In applications where a strong,elastic gel is desired at slight eleva-tions in temperature, METHOCEL Aproducts are recommended. For soft-er, non-rubbery gels, METHOCEL For E products should be used. For aneven softer gel texture, METHOCELK or METHOCEL J products are suggested.

In general, the strength of the gelincreases sharply as molecularweight increases and graduallybecomes constant at or above a viscosity of 400 mPa·s. Gel strengthalso increases with increasing concentration.

Effect of Concentration onThermal Gelation

As the temperature of a solution ofMETHOCEL cellulose ether is raised,hazing of the solution occurs immedi-ately prior to gelation, and the viscos-ity may start to rise. At this point, ifthe concentration is high enough, thesolution will change to a soft or firmgel. If the concentration is below 0.5%,a fluid mixture of individual gel parti-cles and water is formed, rather thana firm gel.

In general, as the concentration of METHOCEL cellulose ether isincreased, the gelation temperaturewill be lowered. An increase of 2% in concentration can cause a 10°Cdrop in the gelation temperature forMETHOCEL A cellulose ether prod-ucts. A 2% increase in concentrationof a solution of METHOCEL F cellu-lose ether product lowers the gelationtemperature by only 4°C.

Interfacial Gelation

In addition to bulk-phase gelation,METHOCEL cellulose ethers alsoexhibit interfacial or surface gelationphenomena as a result of their sur-

factant nature. Interfacial gelationplays an important role in many appli-cations where a protective colloid,emulsification, or surfactant functionis desirable. Examples include: sus-pension polymerization of vinyl chlo-ride; aqueous foam stabilization inshampoos, bubble baths; and thestabilization of non-dairy whippedtoppings and salad dressings.

To achieve bulk thermal gelation,concentrations of 1.5 wt % are generally necessary. However, evenat concentrations as low as 0.001wt %, many METHOCEL productsexhibit surface thermal gelation dueto the migration of polymer moleculesto the air/water interface. Maximumgelation properties are achieved with METHOCEL A, E, and F.

The equilibrium concentration ofMETHOCEL products at any giveninterface depends upon the natureof the interface, presence of othersolvents, temperature, and potentialfor formation of associative structureswith other surfactants. However, theconcentration of METHOCEL at aninterface can be orders of magnitudegreater than that presumed to bepresent in the bulk phase. As a result,surface film formation (surface gela-tion) occurs.

23

Figure 11: Gelation Temperature asa Function of Concentration

1 2 3 4 5 6 7 8 9 10 11 12 Concentration, Wt. %

60

55

50

45

40

35

30

25

Gel

atio

n T

empe

ratu

re,°

C METHOCEL ESlope = -1.0

METHOCEL FSlope = -1.77

METHOCEL ASlope = -2.33

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As a specific example, a 0.01 wt %solution of METHOCEL A 15-LVexhibits surface gelation at 20°C,whereas bulk gelation with the sameproduct would require a concentrationexceeding 12 wt % at such a lowtemperature. A 0.01 wt % solution ofMETHOCEL A 15-LV cannot be madeto undergo bulk gelation at any temperature.

Surface gelation (filming) occurs very rapidly in many solutions ofMETHOCEL products whether diluteor concentrated. This effect is mostevident (and troublesome) when one employs du Nouy tensiometry to determine surface tension.

Generally speaking, increasing themolecular weight, concentration, or temperature of a solution ofMETHOCEL will promote the onset of surface gelation just as in bulk thermal gelation.

Effect of Additives on ThermalGelation

Additives may either increase or decrease thermal-gelation temper-ature, depending on whether theadditive exhibits a coagulant or a sol-ubilizing effect on the METHOCELproduct. For example, solutes suchas ethanol, PEG 400, and propylene glycol all raise the gel points ofMETHOCEL products. This is due to the solubilizing effect which theyimpart. Additives such as glycerin,

sorbitol, and salts lower gel points by lowering the solvency of the aqueoussystem, resulting in a more rapiddehydration of the METHOCEL product(Table 9).

If a manufacturer requires a highthermal gelation temperature andplans to use additives known toreduce the gel temperature, aMETHOCEL product with a gel pointhigher than the temperature requiredshould be used. As the concentrationof the gel-causing additive increases,the thermal gel temperature decreases.Although the behavior of a particularsolute must be determined empirically,the following general guidelinesapply.

24

% METHOCEL METHOCEL METHOCEL METHOCELAdditive Additive A15C, °C F15C3, °C K4M, °C J5M, °C

None 0 50 63 85 62NaCl 5 33 41 59 42MgCl2 5 42 52 67 50FeCl3 3 42 53 76 53Na2SO4 5 salted out salted out salted out salted outAl2(SO4)3 2,5 salted out 45 48 41Na2CO3 5 salted out salted out salted out salted outNa3PO4 2 32 42 52 43Sucrosea 5 51 66 84 60Sucrose 20 44 59 61 53Sorbitol 20 30 46 48 —Glycerine 20 34 60 65-70 55Ethanola 20 >75 >75 >75 >78Polyethylene Glycol 400a 20 52 >80 >80 >78Propylene glycola 20 59 >80 >80 >78

aNote: This material raises the gelation temperature.

Table 9. Effect of Additives on Gelation Temperature for 2% Solutions of METHOCEL Cellulose Ether

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Additives Which Lower Gel Points

Most electrolytes, as well as sucrose,glycerine, etc., lower the gel pointbecause they have a greater affinityfor water and dehydrate the cellulosicpolymer. Decreases in gel temperatureare a function of the ions present inthe additive.

Additives Which Raise Gel Points

The effect of an additive that raises gelpoint varies with different METHOCELproducts. For example, the amount ofpropylene glycol required to increasethe thermal gel point of a solution ofMETHOCEL A cellulose ether by 4˚Cwill increase the gel point of a solu-tion of METHOCEL F by 10˚C andMETHOCEL K by 20˚C.

The increase in the thermal gel pointis directly proportional to the increasein concentration of the additive.Figures 12 and 13 illustrate the rela-tionship between concentrations ofethanol and propylene glycol and thethermal gel point of representativeMETHOCEL products.

25

Figure 13: Effect of Propylene Glycol on Gel Temperature, 2% Solutions

0 5 10 15 20 Propylene Glycol, % by Volume

25

20

15

10

5

0

Cha

nge

in T

herm

al G

el T

emp.

,°C

METHOCEL A4M(4,000 mPa.s)

METHOCEL F4M(4,000 mPa.s)

Figure 12: Effect of Ethanol on GelTemperature, 2% Solutions

0 5 10 15 20 Ethanol, % by Volume

25

20

15

10

5

0

Cha

nge

in T

herm

al G

el T

emp.

,°C

METHOCEL A4M(4,000 mPa.s)

METHOCEL F4M(4,000 mPa.s)

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High-strength, water-soluble films,supported or unsupported, may berolled, cast, or extruded from formula-tions of METHOCEL cellulose etherproducts. These clear, smooth filmsor coatings are impervious to oils,greases, and most solvents. They are also effective binders, even whenloaded with inert materials.

Tensile and elongation properties oftypical films of METHOCEL celluloseethers cast from water are shown inTable 10. The need for a plasticizermay be more pertinent when usinglow viscosity 5 mPa·s METHOCELcellulose ethers because of lower film elongation properties. This canbe more acute if drying temperaturesare too high.

Effect of Additives on Film Solubility

The water solubility of films and coat-ings of METHOCEL cellulose etherscan be altered by the use of

crosslinking compounds and resins.The degree of insolubility can be controlled by the choice and quantityof crosslinking reagent. All ureaformaldehyde, melamine formalde-hyde, and resorcinol formaldehyderesins can be used. Dialdehydessuch as glyoxal are also effective.Supplier literature should be consultedfor selection of catalysts and curingcompounds.

Resistance of Films to Solvents

Films and coatings of METHOCELare unaffected by animal and veg-etable oils, greases, and petroleumhydrocarbons. Of the different types of products, METHOCEL A, METHOCEL F, and METHOCEL Kbrand products are most resistant.

Thermoplastic Forming

Procedures for preparing a dry-mixformulation of METHOCEL E or J cellulose ether products with propy-lene glycol and other plasticizers areavailable for extruded sheeting andinjection or compression molding.Such mixes may be compounded in a ribbon-type blender at room tem-perature and satisfactorily handled bya feeder designed for powders. Mostfeeders perform better if the dry mixis first densified by being passedthrough a set of press rolls or througha pellet mill.

Flakes of METHOCEL E or J cellu-lose ether products with propyleneglycol and other plasticizers may beextruded or molded directly into a fin-ished, water-soluble product at tem-peratures ranging from 80 to 160°C(176 to 320°F). Properly plasticizedsheet and tubing of METHOCELcellulose ether can be heat-sealed at about 130°C (266°F).

Table 10: Properties of Unplasticized Films of METHOCEL

Propertiesa METHOCEL A15LV METHOCEL E15LV

Specific gravity 1.39 1.29

Area factor 24,000 in2/lb/mil 25,860 in2/lb/mil

Moisture vapor transmission rate, 100°F (38°C), 50% RH 67.5 g/100 in2/24 h/mil 65 g/100 in2/24 h/mil

Oxygen transmission rate, 75°F (24°C) 25 cm3/100 in2/24 h/mil 70 cm3/100 in2/24 h/mil

Tensile strength, 75°F (24°C), 50% RH 9,000 Ib/in2 (62 MPa)±10% 10,000 Ib/in2(69 MPa)

±10%Elongation,

75°F (24°C), 50% RH 5-15% 5-15%

Stability to ultraviolet light, 500 h, Fadeometer exposure Excellent Excellent

Resistance to oils and most solvents Excellent Excellent

Ultraviolet transmission (2 mil film)400 nm 55% 82%290 nm 49% 34%210 nm 26% 6%

aTypical properties, not to be construed as sales specifications. Data based on a 1 mil dry film.

26

Properties of Films of METHOCEL

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Measuring Viscosity

Certain precautions must be observedfor the accurate measurement of theviscosity of solutions of METHOCELbecause they exhibit a nonlinearshear stress/shear rate relationship,which results in pseudoplastic viscos-ity behavior at most shear rates.

Dow employs the ASTM referencemethod (D1347 and D2363) as itsstandard procedure. This methodinvolves the use of Ubbelohde vis-cometers, one type for low viscositiesand another for high viscosities. TheUbbelohde viscometer is a precisiondevice which requires only a smalltest sample.

For measuring low viscosity, theappropriate capillary tube size is chosen to obtain a flow time of 50 to 150 seconds (see Table 11). Theviscometer is placed in a 20°C bath,and the length of time required todeliver a given volume through thecapillary tube is measured. The timein seconds is then converted to milli-pascal-seconds (mPa·s). Detailedprocedures are given in currentASTM standards D1347 and D2363.The most reproducible viscosities areobtained by cooling to 4°C and hold-ing for at least one-half hour beforetesting at 20°C.

Viscosity may also be determinedusing a rotational viscometer such asthe Brookfield model LVF† viscome-ter. When the viscosity of a solutionis less than 500 mPa·s, the viscosityis less dependent on shear, and thesolution may be regarded as near-Newtonian. The apparent viscosity of a solution of higher viscosity willbe highly dependent on the rate ofshear, decreasing as the rate ofshear is increased.

The rotational instrument should becalibrated against standard oils. It’s important to note, however, thatthere is no direct correlation betweenUbbelohde and Brookfield measure-ments for non-Newtonian liquids. Fordetails regarding analysis methods,please contact your local sales per-son for METHOCEL.

27

Analytical Methods

†Brookfield Synchrolectric viscometer, BrookfieldEngineering Co., Stoughton, MA.

Table 11: Capillary Tubes for Measuring Viscosity

Viscosity, Size of heavy wall tubing,mPa.s inside diameter

Low viscosity15 25100 400

High viscosity1,500 4,000 8,000 15,000 50,000 75,000

1.5 mm1.8 mm2.4 mm 3.2 mm

5.0 mm6.0 mm7.5 mm 10.0 mm15.0 mm15.0 mm

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Published Analytical Methods

Procedures for the analysis ofMETHOCEL cellulose ether productshave been standardized under ASTMD1372 and ASTM D2372. These andother information on analysis are list-ed in the following references.

Methods for Testing Methylcellulose— Current ASTM D1372, AmericanSociety for Testing and Materials,1916 Race Street, Philadelphia, PA19103.

Methods for Testing HydroxypropylMethylcellulose — Current ASTMD2372, American Society for Testingand Materials, 1916 Race Street,Philadelphia, PA 19103.

Methoxyl and HydroxypropyISubstitution in Cellulose EtherProducts by Gas Chromatography —Current ASTM D3876, AmericanSociety for Testing and Materials,1916 Race Street, Philadelphia, PA19103.

Methylcellulose — Food ChemicalsCodex, Washington, D.C., NationalAcademy of Sciences and NationalResearch Council, Current Edition.

Hydroxypropyl Methylcellulose —Food Chemicals Codex, Washington,D.C., National Academy of Sciencesand National Research Council,Current Edition.

The Determination of Particle SizeDistribution of METHOCEL CelluloseEthers — Dow Method No. Mc-l IA(1973).

Application of Anthrone Test toDetermination of CelluloseDerivatives in Nonaqueous Media —Aldrich, J.C., Samsel, E.P., Anal.Chem. 29, 574-76 (1957).

Hydroxypropyl Methylcellulose —The National Formulary, AmericanPharmaceutical Association,Washington, D.C., Current Edition.

Colorimetric Determination ofMethylcellulose with Diphenylamine— Danzaki, Grace, Berger, EugeneY., Anal. Chem. 31, 1383-5 (1959).

Colorimetric Method forDetermination of Sugars and RelatedSubstances — Dubois, M., Gilles,K.A., Hamilton, J.K., Repers, P.A.,Smith, F., Anal. Chem. 28, 350-356(1956).

Methylcellulose — U.S.Pharmacopoeia, Bethesda, MD, TheUnited States PharmacopoeialConvention, Inc., Current Edition.

Determination of Alkoxyl Substitutionin Cellulose Ethers by Zeisel-GasChromatography — Hodges, K.,Kester, W., Wiederrich, D., Grover, J.,Anal. Chem. 51, 2172-2176 (1979).

28

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Material Safety Data Sheets/SafetyData Sheets for METHOCEL prod-ucts are available from The DowChemical Company to help you fur-ther satisfy your own handling, dis-posal, and safety needs and thosethat may be required by governmentregulations. Such information shouldbe requested prior to handling or use.The following comments are generaland are not a substitute for thedetailed safety information found inthe Material Safety Data Sheet/SafetyData Sheet.

Health

METHOCEL cellulose ether productsresemble the naturally occurring plantand seaweed gums in many of theirchemical, physical, and functionalproperties. All these materials pos-sess a basic carbohydrate structure.

METHOCEL products have hadextensive evaluation and testing inboth acute and long-term feedingstudies in a number of species,including humans. Their many yearsof use in a wide variety of food itemsattests to the safety of METHOCELPremium products.

Although dust from METHOCELcellulose ether products could con-ceivably cause temporary mechanicalirritation to the skin and eyes underextreme conditions and may be con-sidered a nuisance dust if inhaled,the products are considered to pre-sent no significant health hazard inhandling. Please review the handlingprecautions within the Material SafetyData Sheet/Safety Data Sheet formore information.

Flammability

Cellulose ether products are organicpolymers that will burn when exposedto heat and a sufficient oxygen sup-ply. Fires can be extinguished by con-ventional means, avoiding any raising

of dust by strong water jets. Dow rec-ommends the use of water spray, car-bon dioxide, or powder extinguishers.

Storage

Caution: A fine dust of this material iscapable of forming an explosive mix-ture with air. Powder samples shouldnot be exposed to temperaturesabove 135 to 145°C. Samples maydecompose and lead to a possibledust explosion. As in storage of anydusts or fine powders, good house-keeping is required to prevent dustsin air from reaching possibly explo-sive levels. When handling in largequantities or in bulk, the general precautions outlined in NFPA 63,“Prevention of Dust Explosions inIndustrial Plants,” and in NFPAbulletins 68, 69, and 654 are recommended.

With METHOCEL cellulose etherproducts with particle sizes of 74 µmor less (finer than 200 mesh), criticallevels are reached at concentrationsof 28 g/m3 (0.03 oz/ft3). The minimumignition energy required to cause adust explosion is 0.030 joules. Staticfrom a human body has about 0.025joules. This is normally not enoughenergy to ignite the powder.

As with any organic chemical material,METHOCEL cellulose ethers shouldnot be stored next to peroxides orother oxidizing agents.

Accidental Spills and Housekeeping

Solutions of METHOCEL celluloseethers are slippery. To preventemployee falls and injury, floor spillsof dry powder should be thoroughlyvacuumed or swept up. Any slightresidual product on the walls or floorcan then be flushed with water into a sewer. If the spill is a viscous solu-tion, it should be further diluted withcold water before disposal. Likewise,

accumulation of dust should beavoided to control this hazard.

Disposal

Despite the very slow rate ofbiodegradation, cellulose ether prod-ucts should not present any hazard in the waste/soil compartment. Theirbehavior is similar to wheat flour orsawdust. Although Dow studies usingstandard procedures showed no 5-day, 10-day, or 20-day BOD values,activated sludge studies with (14C)methylcellulose showed that methyl-cellulose was 96% degraded or otherwise removed from solution in20 days. Thus, METHOCEL celluloseethers should present no ecologicalhazard to aquatic life.

Because METHOCEL cellulose etherproducts and their aqueous solutionspresent no significant ecologicalproblems, they can be disposed of by industrial incineration or in anapproved landfill, providing regulationsare observed. Incineration should bedone under carefully controlled condi-tions to avoid the possibility of a dustexplosion. Customers are advised toreview their local, state, provincial or national regulations governing the disposal of waste materials todetermine appropriate means of dis-posal in their area.

Customer Notice

Dow encourages its customers toreview their applications of Dow products from the standpoint ofhuman health and environmentalquality. To help ensure that Dow prod-ucts are not used in ways for whichthey are not intended or tested, Dowpersonnel will assist customers indealing with ecological and productsafety considerations. Your Dowsales representative can arrangeproper contacts.

29

Handling Considerations

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-NOTICE: No freedom from any patent owned by Seller or others is to be inferred. Because use conditions and applicable laws may differ from onelocation to another and may change with time, Customer is responsible for determining whether products and the information in this document areappropriate for CustomerÕs use and for ensuring that CustomerÕs workplace and disposal practices are in compliance with applicable laws and othergovernmental enactments. Seller assumes no obligation or liability for the information in this document. NO WARRANTIES ARE GIVEN; ALL IMPLIEDWARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED.

Printed in U.S.A. *Trademark of The Dow Chemical Company Form No. 192-01062-400XGWPublished June 1997

For more informtion, complete literature, and product samples you can reach a Dow representative at the following numbers:

From the United States and Canada call 1-800-447-4369fax 1-517-832-1465

From Mexico call 95-800-447-4369 fax 95-517-832-1465

In Europe call + 31/20.691.6268fax + 31/20.691.6418

Or you can contact us on the Internet at www.methocel.com