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  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20071

    Recent Candle Stabilization

    Developments at Ciba

    Second World Candle Congress

    June 2007

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20072

    Overview of Discussion Topics

    Stabilizer Additive Technology

    Historical Developments and Current Needs in the Candle Industry

    Soy Wax Candles Stabilization Study

    The Challenge of Fragrance Oil StabilizationSome Preliminary

    Observations

    Candle Stabilization RefinementsIdeas for Doing It Better

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20073

    Candle Stabilization

    Scented candles are complex chemical systems prone to

    degradation when exposed to light and heat.

    Waxes: different types and blends for different candle applications

    Paraffin

    Microcrystalline

    Vegetable> Soy

    > Palm

    > Cottonseed

    Dyes

    Fragrances: typical functional groups include

    Aromatics and phenolics

    Aldehydes, ketones and esters

    Ethers and alcohols

    Olefins

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20074

    Degradation MechanismFree Radicals

    Free radicalsAtomic or molecular species with unpaired

    electrons on an otherwise open shell configuration. These

    unpaired electrons are usually highly reactive.

    FormationBy exposure of a substance to light energy or by

    thermal cleavage of a chemical bond.

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20075

    Bond Cleavage Due to Light Absorption

    Absorption of light is the reaction of light with a material

    (chromophore).

    Different functional groups and molecules absorb different

    wavelengths (energies) of light.

    Single bonds correlate to very high energy light or shorter overall

    wavelengths (less susceptible to cleavage).

    Double () bonds are responsible for light absorption (more

    susceptible to cleavage).

    Polar groups also give rise to reactivity with light.

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20076

    Bond Cleavage Due to Light Absorption

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20077

    Auto-oxidation Process Induced by Light and Heat

    R R* R. (alkyl radical)

    R. ROO. (peroxy radical)

    ROO. ROOH + R. (hydroperoxide & alkyl radical)

    ROOH RO. + .OH (alkoxy & hydroxyl radicals)

    This is a chain-propagating process.

    h

    O2

    RH

    h or

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20078

    Stabilizer Additives to Interrupt the Auto-oxidation Process

    UV Absorbers (UVA)

    Prevent damage caused by free radical formation when a substrate is exposed to light.

    Absorb UV light energy at specific wavelengths and dissipate this energy as heat.

    Hindered Amine Light Stabilizers (HALS)

    Scavenge oxygen-centered and alkyl free radicals.

    Cyclic mechanism with regeneration of active chemical species.

    Antioxidants (AO)

    Scavenge oxygen-centered free radicals.

    Phosphite Process Stabilizers

    Decompose hydroperoxides.

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 20079

    Where Stabilizer Additives Act to Disrupt Degradation

    R R* R. Counter with UVA

    R. ROO. Counter with HALS

    ROO. ROOH + R. Counter with HALS, AO

    ROOH RO. + .OH Counter with Phosphite

    h

    O2

    RH

    h or

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200710

    UVA Examples

    BenzophenonesLower photo-permanence, coverage better in short wavelength

    range

    BenzotriazolesHigher photo-permanence, good coverage over broad

    wavelength range

    O OH

    OR

    NN

    N

    OH

    R

    R

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200711

    UVA MechanismKeto-Enol Tautomerism

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200712

    Hindered Amine Light Stabilizers

    Substituted Tetramethyl Piperidines

    NR1

    R2

    R1 = Head Group R2 = Backbone

    Activity

    Basicity

    Compatibility

    Solubility/compatibility

    Equivalent Wt.

    Basicity

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200713

    HALS Examples

    Amine Typehigh basicity, pKb= 5.1-5.5

    Amino-ether Typelow basicity, pKb= 9.6, does not interact with acids,

    metals

    NH3C

    H

    O.CO.(CH2)8.CO.O

    N

    H

    CH3

    NC8H

    17.O

    H

    O.CO.(CH2)8.CO.O

    N

    H

    O.C8H

    17

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200714

    HALS Proposed MechanismCyclic Regeneration

    N

    A

    XE C

    RH

    N

    O

    X

    N

    O

    X

    E

    R

    E C R

    O

    H

    O

    E C R

    O

    E C R

    OH

    H

    A = H, alkyl, alkoxy, carbonyl

    ROO.

    Key initiating

    step

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200715

    Use of Stabilizer Additives in Candles

    Conventional Technologyadequate for candles made with highly-refined

    paraffin wax and with minimal fragrance component

    Benzophenone and/or benzotriazole UVAs (typically in solid form)

    No free radical scavenging

    Advanced Technologyprompted by the destabilizing impact of increased

    fragrance oil loadings

    Synergistic blend of benzotriazole UVA and non-interacting HALS in liquid form

    UV absorption and free radical scavenging

    Latest Developments

    Increased cost and decreased availability of paraffin wax

    Widespread substitution of vegetable waxes for petroleum-based waxes

    How well will stabilizer packages proven in paraffin wax work in vegetable wax?

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200716

    Soy Wax Candles Stabilization Study

    WaxNatureWax Container Candle Blend C-3 from Cargill

    Hydrogenated vegetable glycerides

    Mettler dropping point = 125 - 130 F

    Iodine value = 50 - 56

    Three representative candle formulations:

    Vanilla fragrance with no dye,

    Hydrangea fragrance with blue dye,

    Cinnamon fragrance with red dye.

    Three light stabilizer (LS) options:

    No light stabilizer,

    0.3% w/w of conventional LS package (1:1 blend of benzophenone and

    benzotriazole UVAs)

    0.3% w/w of advanced LS package (1:1 blend of benzotriazole UVA and non-

    interacting HALS)

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200717

    Soy Wax Candles Stabilization StudyAdditives Tested

    BP1 (solid benzophenone UVA)

    BZT1 (solid benzotriazole UVA)

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200718

    Soy Wax Candles Stabilization StudyAdditives Tested

    BZT2 (liquid benzotriazole UVA)

    HALS1 (liquid, non-interacting hindered amine light stabilizer)

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200719

    Accelerated Light Exposure Tests

    Pre-exposure and post-exposure color measurements of all candle

    samples were made with an X-Rite SP 64 spectrophotometer

    (D65 illuminant, 10 degree observer).

    Control samples were stored in the dark inside sealed plastic bags.

    Test samples were placed in a light box:

    Open upper level equipped with 3 double banks of cool-white

    fluorescent tubes (34 Watts each)

    Enclosed, ventilated lower level equipped with 3 double banks of

    black light (UV) tubes (40 Watts each)

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200720

    Equipment for Accelerated Light Stability Testing

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200721

    Quantifying Color Stability

    CIELAB color scale system

    L* signifies lightness/darkness

    a* signifies red/green color axis

    b* signifies yellow/blue color axis

    E* = [(L*)2 + (a*)2 + (b*)2]1/2

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200722

    Soy Wax Candles Light Stability Test3 Weeks UV Light Exposure

    No LS

    0.3% BTZ2/HALS1

    0.3% BP1/BTZ1

    Vanilla, no dye

    Hydrangea, blue dye

    Cinnamon, red dye

    0

    5

    10

    15

    20

    25

    30

    35

    40

    delta E*

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200723

    Soy Wax Candles Light Stability Test5 Weeks Fluorescent Light Exposure

    No LS

    0.3% BTZ2/HALS1

    0.3% BP1/BTZ1

    Vanilla, no dye

    Hydrangea, blue dye

    Cinnamon, red dye

    0

    5

    10

    15

    20

    25

    30

    35

    40

    delta E*

  • Ciba Specialty Chemicals

    Business Line Coatings

    Robert Waldron, June 200724

    Fragrance Oil Impact

    Impact of 330 hours UV light exposure on paraffin wax candle with blue dye in the

    absence