dynamics of timber floor coatings scaa conference 2019€¦ · derived from vegetable and animals...

COATINGS

Dynamics of Timber Floor Coatings SCAA Conference 2019

GeorgeZavras

COATINGS Excellence in Polyurethane Chemistry

•  What are Timber floor coatings? •  Brief history of Timber Floor Coatings

•  How do these product work on Timber floors? •  Important properties of Timber Floor Coatings

•  What are the challenges for Timber Flooring products? •  The nature of timber •  Environment, Application and Expectations / Trends

•  What are manufacturers doing to support applicators in getting a better product?

•  Industry standards and expectations •  Communication and guidelines

Presentation Format


Timber Floor Coatings are typically described as; •  A vehicle which consist of a film former or RESINS and solvents •  In addition to additives which exist in small quantities which improve; stability

shelf-life, flow and levelling, surface tension, adhesion etc…

Resins; Resins bond to the wood surface which gives the coating system its desired physical properties such as film thickness, solid content, drying time, hardness, chemical resistance and general wear and tear

Types of Resins; Oils, natural resins and gums, alkyd resins, Polyester resins, Phenolic resins, Polyurethane resins, Epoxy resins, Nitrocellulose, Chlorinated rubber, acrylic and associated polymers (Polyurethane Dispersions & Hybrid polymers etc.)

What are Timber Floor coatings? A brief history of timber floor coatings



•  Earliest timber floor coatings were mostly oils derived from vegetable and animals

•  Oils are classified by their film forming ability from drying, semi-drying and non-drying oils

1.   Drying: Linseed Oil and Tung Oil 2.   Semi-drying: Safflower Oil, Sunflower

oil, Soya bean oil 3.   Non-drying: Cottonseed Oil, coconut

oil and rapeseed oil •  Linseed Oil was probably one of the first

coating systems which gave some resistance for timber floors

•  Natural resins and gums such as Kino and Shellac used with an alcohol such as methylated spirits which were hand rubbed onto the timber surface usually by French Polishers


•  Alkyd Resins started to develop by modifying vegetable or fish oils

•  Polyester resins extremely short pot-life which wasn’t suitable for brushing or rolling

•  Oleo resinous varnishes provided for the first time support for LIGHT foot traffic on timber Floors.

•  Phenolic resins or modified oils were mixed with mineral turps to achieve the desired viscosity

•  Regular application of beeswax was required to maintain these floors




•  Polyurethane four categories; 1.   Hybrid Polyurethane or Modified polyurethane Oils: 2.   One pack moisture-cured: 3.   One pack moisture-cured Catalysed 4.   Two pack polyurethane reaction with polyols

•  Epoxy Resins: thermosetting coating which are two pack in nature •  Nitrocellulose: Purified cellulose reacted with acid. Could have

explosive risk. Very fast drying and setting.



Water-borne polyurethane, acrylics and other polymers •  polymers dispersed into an emulsion in water •  Can range from full polyurethane (PUD) to Hybrid-modified •  Acrylic, oil and alkyd modified dispersions •  As contained in water, the wetting characteristics on timber varies from

traditional solvent based coatings •  Cannot achieve a high gloss equal to one pack or two pack polyurethanes. •  Typically subdued in gloss

Ultraviolet curable and L.E.D Curable


How do these product work on Timber floors?

Important properties of Timber Floor Coatings

•  All binders, resins and film-formers are selected appropriately for each use on a timber floor.

•  When selecting the appropriate resin system things to consider are: •  Useability – manufacture and end use •  Drying mechanism and rate •  Flexibility •  Hardness •  Chemical resistance •  Adhesion •  Appearance

•  Each system needs to be applied uniformly on a horizontal Surface. •  To achieve this each resin needs to be delivered in solution with “Solvent”. •  Types of solvent:

•  Hydrocarbons – Aliphatic and Aromatic hydrocarbons (e.g. xylene) •  Organic solvents – alcohol and ketones (e.g. methylated spirits, MEK, BA •  Water – may require high molecular weight co-solvents although low VOC



Important properties of Timber Floor Coatings Additives Play an important role in the final performance of timber floor coatings. Include; curing rates, ease of application, in-can stability and anti-bacteria. Additives make up around 1% to 5% of a timber coating formulation. •  Driers – needed in oil based coatings to promote drying through oxidation •  Thixotropic additives – viscosity build in can for anti-settling especially for

reduced sheen products •  Anti-oxidants – to ensure clarity of film but as well anti-skinning properties •  Defoamers – reducing of foam due to CO2 production and aerate application •  Surface tension modifiers – assist with breaking or bursting of foam

formation and assist with ‘rejection’ on timber •  Anti-floating and wetting control – reduces mottling or streaking •  Biocides – used to treat timber of mould but as well can be used to

stabilise water-borne products



Important properties of Timber Floor Coatings

Properties to consider: •  Ease of use

•  Stable and easy to mix •  No interaction with natural contaminants within timbers •  Can be easily applied with conventional equipment such as roller and brush

•  Viscosity •  Measured typically in seconds or centipoise •  Viscosity can determine the film build and also the feel of the coating system

•  Dry time •  Will reflect the final appearance but also determines application work flow

and return of service •  Durability

•  Which chemistry will give the best product-life •  Film build or percent solids •  Chemical resistance and scratch resistance •  Hardness



Important properties of Timber Floor Coatings Typical systems: •  Three coat system (1 x sealer + 2 x Topcoats) •  Application rate by roller ~1L per 10m2 (100um WFT) •  Final film build of ~100um dry (if coating system is around 50% solids) •  First coat is typically a SEALER coat •  Sealers can also determine the final colour or appearance for the timber •  The deeper the penetration of into timber the deeper the colour •  Topcoats typically come in High gloss, semi-gloss, satin, matt and natural

Preparation of timber (sanding): •  Drum sanding with 40 to 60 grit followed by 80 to 100 grit •  Finished with 120 grit before application of coating •  Frictional heat can get up to 70°C+ •  This heat can cause natural tannins and contaminants to rise to the surface



Important properties of Timber Floor Coatings The reality of the timber flooring coatings: •  Manufacturers have to satisfy two main targets

1.   Applicator (floor sander) 2.   Asset owner (house owner)

Applicators: •  Easy to use – hassle free •  Confidence in a brand or product •  Speed of application – get in and out •  Know the outcome before they start a job •  Cost $$$

Asset Owners: •  Final finish appearance - Gloss to Matt •  Durability over time – wear and tear •  ‘environmentally friendly’ – Non-hazardous - safe •  What Level of maintenance required •  Guarantees


What are the challenges for Timber Flooring products?

The Nature of Timber

There are three essential chemical components of wood:

•  Cellulose (40% – 45%) •  Hemicellulose (15% - 30%) •  Lignin (22% to 30%)

•  A tree’s growth starts with sap wood and heartwood which is eventually converted into inert heartwood

•  Earlywood (springwood) and Latewood (summerwood) – which can give differences in physical properties of the timber species


•  Softwoods and hardwoods – Sawn into timber for commercial use

•  The term “soft” has no relation to the ‘softness’ of timber

•  The terms hardwood and softwood are distinctions of the structure being “porous” and “non-porous”.

•  Hardwoods identification are much easier compared to softwoods

•  Density is the most important characteristic of a species which indicates its strength






Extractives: •  Wood contains a wide range of

compounds which can be extracted by ‘solvents’

•  Not essential although important to wood properties such as;

•  Density, odour, colour, taste, flammability and hygroscopcity

•  Can also be polyphenols (oils, waxes, gums and resins)

•  Can represent from 5% to 30% of dry wood mass

•  Can be removed by wood by extraction using alcohol, organic solvents and water


Types of Extractives: •  Exudates – when a tree is damaged or

‘injured’ a protective response will release resins such as Kino in exculpates which is soluble in alcohol.

•  Phenolic compounds – Flavones, stilbenes, quinones, lignin and tannins which are typically classified as polyphenols (more common in hardwood)

•  Minerals – elements absorbed by roots may remain in timbers such as calcium and iron

•  Silica – High silica content in timbers can effect sanding





The Nature of Timber Influence of extractives on wood when applying timber coatings: •  Staining – solvents and water can leach

extractives out of timber which can stain or discolour the timber and the area around it. Tannins in particular are likely to react with surfaces such as concrete

•  Durability – rejection by certain types of phenolic compounds (polyphenols) which can restrict uptake of solvent and water

•  Colour – Flavones and Quoins (polyphenols) when exposed to sunlight undergo chemical change, hence can change colour.

•  Finishes – sunlight and heat can make polyphenols transfer through a timber plank. Even when coated an absorption could occur where gums and resins can end up sticking the surface of the coating and will need to be physically removed with a knife or blade.



The Nature of Timber Other properties of timber: •  Knots – can contain high

concentration’s of extractives •  Visual characteristics – texture, grain

and figure •  Tree growth – Wood structure,

absorption of minerals and conversion of sapwood to heartwood greatly determined by tree growth and time

•  Identifying species – it’s often hard to determine certain types of species

•  Oxidation – can cause rusting of nails •  Absorption of timber – the deeper a

coating is absorbed the darker the appearance of the surface.

•  Moisture content – Australian standard 9% to 14% for timber flooring

Friction resistance: •  Coefficient of friction will vary per timber

species •  Timber coatings will also change the

coefficient of friction •  Timber floor coatings can greatly

improve abrasion resistance for timber floors



Environment and application Environmental factors: •  Temperature (°C) – Drying rates, evaporation rates and curing rates. Can also

effect extractives and final appearance •  Humidity (%) – Moisture curing reaction rate, evaporation rates and moisture

content of timber •  Airflow – drafting of air can effect final appearance and evaporation rates •  Weather conditions –acclimatisation of timber – sunlight on floors


Application of timber coatings: •  Application tool – 10mm roller v.s 6mm

naps roller •  Application rate – 1L per 10m2 v.s 1L

per 5m2 •  Drying times – lap marks, picture

framing and stop marks •  Hazardous substance – Low VOC v.s

High VOC •  Final appearance – High Gloss v.s Low

Gloss v.s Colour Expectations & Trends: •  Coating will survive an ‘x’ number of

years •  Colour and appearance to be achieved –

Satin finish with a teak brown etc.. •  Non-hazardous materials used on

assets •  Return to service


Environment and application


Summary so far……………

The perfect timber floor coating: •  Selection of resin/binder/film-formers + selection of solvent for optimal performance •  Flow onto surface of selected timber species, easy to use with conventional tools

brush and roller. Able to be workable with a floor sander. •  Absorption into pores of timber to ensure adhesion although avoid reaction

with polyphenols such as tannin and lignin. •  Avoid reaction with ‘other’ products on the surface such as timber putty and nails •  Moisture content, temperature, humidity and airflow to ensure film formation and

consistent drying and even finish •  Abrasive enough to allow sand-ability of layers of coats with different type abrasives

such as 80grit to 220grit •  Reapplication and inter-coat adhesion •  Final appearance to look monolithic and to the asset owners satisfaction (consistent) •  Durability – chemical resistance, traffic resistance, clean ability, UV resistance and

colour •  Expectations – will survive1 year, 3 years, 6years, 10 years…???


Summary so far……………


What are manufacturers doing to support applicators in getting a better product?

•  Associations such as Australasian Timber Flooring Association (ATFA) provides industry standards to professional but as well sets expectations to the market

•  Government bodies enforcing laws or rules such as the BCA. All commercial and residential stair treads must meet a P3 or R10 rating for wet slip testing.

•  Manufacturers are working closely with raw material suppliers to ensure new chemistries are tested on Australian timbers to ensure compatibility

•  Manufacturers are working closely with end decision makers to ensure realistic expectations are met for finished products (e.g it is impractical to expect a furniture finish for the floor)


•  Manufacturers are communicating the differences between chemistries such as; Water-Borne polyurethanes V.S Solvent Based Polyurethane

•  Extensive field testing and trials on Australian timber species are performed before any products are commercialised and released to the market

•  Definitions such as non-yellowing, non-hazardous and low VOC are being defined more precisely

•  Ultimately Manufacturers are making products more user friendly to increase likely hood of job success

What are manufacturers doing to support applicators in getting a better product?


References

Literature: •  Wood in Australia Types, Properties and uses – Keith R. Bootle 1998 •  Urethane Coatings – “Guide to using timber coatings manual 2017” •  Textbook of Wood Technology, Vol 1 – Panshin & Zeeuw 1970 •  Environmentally acceptable coatings for the wood industry – Bufkin &

Wildman 1980 •  Australian timber flooring asscoiation – information guides

Websites: •  http://www.urethanecoatings.com.au •  https://www.atfa.com.au/ •  http://www.erapol.com.au •  https://www.architectureanddesign.com.au/ •  https://www.boral.com.au/australian-hardwood-timber-species •  https://www.woodsolutions.com.au


QUESTIONS?

dynamics of timber floor coatings scaa conference 2019€¦ · derived from vegetable and animals...

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