Patent Application
20130053499
This invention relates to thickened aqueous dispersions of certain large polymeric particles. More particularly, this invention relates to an aqueous composition including: a particulate polymer having a particle diameter of from 0.5 microns to 150 microns, the polymer comprising, as copolymerized units, from 0.1% to 50%, by weight based on polymer weight, monomer having a Hansch parameter of from 2.5 to 10, the polymer having been formed in the presence of a non-formaldehyde reductant; and from 0.1% to 5%, by weight based on polymer weight, thickener. This invention also relates to a method for providing a coating on a substrate and the coated substrate so provided.
Stabilizing large particle polymers from sedimentation and separation in an aqueous mixture is difficult due to concepts included in Stokes law (Introduction to Fluid Dynamics, Cambridge University press, GK Batchelor (1967)):
F
d=−6πμRVs, where:
When spherical particles settle in a viscous fluid due to gravity influence on the mass of the particle, then a settling velocity is achieved when the forces due to friction combined with the buoyancy forces balance the gravitational forces. The settling velocity is given by:
where:
In other words VS is proportional to the size of the particle and inversely proportional to the viscosity of the fluid.
The settling velocity of a particle of a given size can be reduced by increasing the viscosity of a fluid. Within narrow polymer compositions and particle size ranges, particles generally exhibit a similar viscosity when formulated similarly using thickeners or rheology modifiers.
U.S. Pat. No. 7,829,626 discloses matte coatings for leather including a binder component and certain copolymer duller particles having an average diameter of 1-20 microns.
It is desired to provide particles having a diameter of from 0.5 micron to 150 microns and denser than water settle to the bottom of a dispersion more slowly, preferably without producing a structured sediment that is very difficult to re-disperse. We have found that a particular composition of large substantially spherical particles (0.5 microns to 150 microns in diameter) provides for comparatively increased thickening efficiency when formulated with equal amounts of thickeners or rheology modifiers.
In a first aspect of the present invention there is provided an aqueous composition comprising: a particulate polymer having a particle diameter of from 0.5 microns to 150 microns, said polymer comprising, as copolymerized units, from 0.1% to 50%, by weight based on polymer weight, monomer having a Hansch parameter of from 2.5 to 10, said polymer having been formed in the presence of a non-formaldehyde reductant; and from 0.1% to 5%, by weight based on polymer weight, thickener.
In a second aspect of the present invention there is provided a method for providing a coated substrate comprising; (a) forming the aqueous coating composition of the first aspect of the present invention; (b) applying said aqueous coating composition to a substrate; and (c) drying, or allowing to dry, said applied aqueous coating composition.
In a third aspect of the present invention there is provided a coated substrate formed by the method of the second aspect of the present invention.
The aqueous polymeric coating composition of the present invention includes a particulate polymer having a particle diameter of from 0.5 microns to 150 microns, the polymer including, as copolymerized units, from 0.1% to 50%, by weight based on polymer weight, monomer having a Hansch parameter of from 2.5 to 10. By “aqueous composition” herein is meant a composition in which the continuous phase is predominantly water; water-miscible compounds may also be present, preferred is water.
The particulate polymer having a particle diameter of from 0.5 microns to 150 microns may be formed by methods known in the art such as, for example emulsion polymerization, seeded growth processes, and suspension polymerization processes. Such polymers are described, for example, in U.S. Pat. Nos. 4,403,003; 7,768,602; and 7,829,626, and also exemplified herein. The polymer may be may be made in a single stage process, a multiple step process such as a core/shell process that may result in a multiphase particle or in a particle in which the phases co-mingle for a gradient of composition throughout the particle, or in a gradient process in which the composition is varied during one or more stages.
The particulate polymer includes, as copolymerized units, from 0.1% to 50%, preferably from 0.2% to 25%, more preferably from 0.3% to 10%, and most preferably from 0.3% to 1%, by weight based on polymer weight, monomer having a Hansch parameter of from 2.5 to 10, preferably of from 2.5 to 7.0. For the specific monomers in Table 1, the Hansch parameter to be used herein is the following:
The Hansch parameters presented above were calculated from the US EPA Kowwin software and values for monomers not presented in Table 1 may be so calculated. Alternatively, the Hansch parameter for monomers not presented in Table 1 may be calculated using a group contribution method as disclosed in Hansch and Fujita, J. Amer. Chem. Soc., 86, 1616-1626 (1964); H. Kubinyi, Methods and Principles of Medicinal Chemistry, Volume 1, R. Mannhold et al., Eds., VCH, Weinheim (1993); C. Hansch and A. Leo, Substituent Constants for Correlation Analysis in Chemistry and Biology, Wiley, New York (1979); and C. Hansch, P. Maloney, T. Fujita, and R. Muir, Nature, 194. 178-180 (1962).
The particulate polymer includes, as copolymerized units, in addition to at least one monomer having a Hansch parameter of from 2.5 to 10, ethylenically unsaturated monomer such as, for example, a (meth)acrylic ester monomer including methyl(meth)acrylate, ethyl(meth)acrylate, butyl acrylate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, ureido-functional (meth)acrylates and acetoacetates, acetamides or cyanoacetates of (meth)acrylic acid; vinyl acetate or other vinyl esters; vinyl monomers such as vinyl chloride, vinylidene chloride, and N-vinyl pyrollidone; (meth)acrylonitrile; and N-alkylol(meth)acrylamide. The use of the term “(meth)” followed by another term such as (meth)acrylate or (meth)acrylamide, as used throughout the disclosure, refers to both acrylates or acrylamides and methacrylates and methacrylamides, respectively. In certain embodiments the particulate polymer includes a copolymerized multi-ethylenically unsaturated monomer such as, for example, allyl(meth)acrylate, diallyl phthalate, 1,4-butylene glycol di(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and divinyl benzene. In certain embodiments the particulate polymer includes a copolymerized acid monomer including carboxylic acid monomers such as, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, and maleic anhydride; and sulfur- and phosphorous-containing acid monomers. Preferred acid monomers are carboxylic acid monomers. More preferred monomers are (meth)acrylic acid.
The calculated glass transition temperature (“Tg”) of the particulate polymer is from −60° C. to 150° C. When the particulate polymer includes more than one composition such as a multiphase polymer, a multistage polymer, or the like, the calculated Tg is taken as the Tg of the overall composition without regard for the number of separate compositions therein. Tgs of the polymers herein are calculated herein by using the Fox equation (T. G. Fox, Bull. Am. Physics Soc., Volume 1, Issue No. 3, page 123 (1956)). that is, for calculating the Tg of a copolymer of monomers M1 and M2,
1/Tg(calc.)=w(M1)/Tg(M1)+w(M2)/Tg(M2)
, wherein
Tg(calc.) is the glass transition temperature calculated for the copolymer
w(M1) is the weight fraction of monomer M1 in the copolymer
w(M2) is the weight fraction of monomer M2 in the copolymer
Tg(M1) is the glass transition temperature of the homopolymer of M1
Tg(M2) is the glass transition temperature of the homopolymer of M2,
all temperatures being in ° K.
The glass transition temperature of homopolymers may be found, for example, in “Polymer Handbook”, edited by J. Brandrup and E. H. Immergut, Interscience Publishers.
In the formation of the particulate polymer conventional surfactants may be used such as, for example, anionic and/or nonionic emulsifiers such as, for example, alkali metal or ammonium alkyl sulfates, alkyl benzene sulfonates, alkyl sulfonic acids, fatty acids, and oxyethylated alkyl phenols. The amount of surfactant used is usually 0.1% to 6% by weight, based on the weight of total monomer. Conventional free radical initiators may be used such as, for example, hydrogen peroxide, t-butyl hydroperoxide, t-amyl hydroperoxide, t-butylperoxy-2-ethyl hexanoate, ammonium and/or alkali persulfates, typically at a level of 0.01% to 3.0% by weight, based on the total monomer weight. Such initiators coupled with, as reductant or activator, a non-formaldehyde reductant, are used in the formation of the particulate polymer, optionally in combination with metal ions such as, for example iron and copper, optionally further including complexing agents for the metal. By “polymer having been formed in the presence of a non-formaldehyde reductant” is meant herein that the reductant is added to the reaction zone before, during, or after the addition of the monomer that is being converted to the particulate polymer and that other classes of reductant are absent during the reaction. By “non-formaldehyde reductant” herein is meant that the reducing agent does not contain formaldehyde or release formaldehyde under reaction conditions except for an amount of from 0% to 0.01% by weight formaldehyde based on total monomer weight. Non-formaldehyde reductants include, for example, the reductants: isoascorbic acid, sodium metabisulfite, sodium hydrosulfite, and BRUGGOLITE™ FF6 (a sodium salt of an organic sulfinic acid derivative). Preferred as non-formaldehyde reductant is from 0.01% to 0.5%, by weight based on total monomer weight, isoascorbic acid. The monomer mixture for the particulate polymer or for a stage thereof may be added neat or as an emulsion in water. The monomer mixture for the particulate polymer or for a stage thereof may be added in a single addition or more additions or continuously over the reaction period allotted for that stage using a uniform or varying composition. Additional ingredients such as, for example, preformed emulsion polymers also known as seed polymer, free radical initiators, oxidants, reducing agents, chain transfer agents, neutralizers, surfactants, and dispersants may be added prior to, during, or subsequent to any of the stages.
The aqueous composition of the present invention also includes from 0.1% to 5% by weight based on polymer weight, thickener. The thickener is selected from associative, partially associative, and non-associative thickeners, and mixtures thereof, in an amount sufficient to increase the viscosity of the aqueous composition. Suitable non-associative thickeners include water-soluble/water-swellable thickeners and associative thickeners. Suitable non-associative, water-soluble/water-swellable thickeners include polyvinyl alcohol (PVA), alkali soluble or alkali swellable emulsions known in the art as ASE emulsions, and cellulosic thickeners such as hydroxyalkyl celluloses including hydroxymethyl cellulose, hydroxyethyl cellulose and 2-hydroxypropyl cellulose, sodium carboxymethyl cellulose (SCMC), sodium carboxymethyl cellulose, 2-hydroxyethyl cellulose, 2 hydroxypropyl methyl cellulose, 2-hydroxyethyl methyl cellulose, 2-hydroxybutyl methyl cellulose, 2-hydroxyethyl ethyl cellulose, starches, modified starches, and the like. Suitable non-associative thickeners include inorganic thickeners such as fumed silica, clays (such as attapugite, bentonite, laponite), titanates and the like. Suitable partially associative thickeners include hydrophobically-modified, alkali-soluble emulsions known in the art as HASE emulsions, hydrophobically-modified cellulosics such as hydrophobically-modified hydroxyethyl cellulose, hydrophobically-modified polyacrylamides, and the like. Associative thickeners include hydrophobically-modified ethylene oxide-urethane polymers known in the art as HEUR thickeners.
The particulate polymers having a particle diameter of from 0.5 microns to 150 microns, preferably from 0.5 microns to 100 microns, more preferably from 0.7 microns to 50 microns, and most preferably from 0.8 microns to 20 microns, are useful, for example, as matting agents and feel modifiers for coating formulations. In many cases the large spherical particles are manufactured in a location that is different from the location of the final coating formulation. In other cases the final formulation is made at the same location of the large spherical particle but not in a timely fashion. Such strategies require storage of the large spherical particles until ready for final formulation. In either of these cases it is necessary to stabilize the large spherical particle so that it can be shipped to another location or it can be stored until a later date. This typically requires adding a thickening agent to the large spherical particles at its point of manufacture. In many cases the stabilization thickener is not beneficial to the final coating formulation and it is desirable to minimize the quantity of thickener used to stabilize the large spherical particle so as to reduce negative consequences of the stabilizing thickener in the final coating formulation.
The aqueous composition of the present invention is prepared by techniques which are well known in the coatings art. First, pigment(s), inorganic or organic, extenders, etc., if desired, are well dispersed in an aqueous medium under high shear such as is afforded by a COWLES (R) mixer or predispersed pigments, colorant(s), or mixtures thereof are used. The particulate polymer is added under low shear stirring along with other coatings adjuvants, if desired. The aqueous composition may contain, in addition to the particulate polymer and thickener, film-forming or non-film-forming solution, dispersion, or emulsion polymers in an amount of 0% to 500% by weight based on the weight of the particulate polymer, such as, for example, an emulsion polymer or a polyurethane dispersion having a calculated Tg of from −60° C. to 150° C. and a particle diameter of from 50 nm to 490 nm. Additionally, conventional coatings adjuvants such as, for example, emulsifiers, coalescing agents, plasticizers, antifreezes, curing agents, buffers, neutralizers, humectants, wetting agents, biocides, antifoaming agents, UV absorbers, fluorescent brighteners, light or heat stabilizers, chelating agents, dispersants, colorants, waxes, mineral extenders, water-repellants, and anti-oxidants may be added. In certain embodiments a photosensitive compound such as, for example, benzophenone or a substituted acetophenone or benzophenone derivative as is taught in U.S. Pat. No. 5,162,415 may be added. In certain embodiments the aqueous coating composition of the invention has a VOC (volatile organic compound) level of 150 or less g/liter of coating, alternatively of 100 g/lter or less, or further alternatively of from 0 g/liter to 50 g/liter or less.
The solids content of the aqueous coating composition may be from 10% to 70% by volume. The viscosity of the aqueous coating composition may be from 50 mp-s to 50,000 mp-s, as measured using a Brookfield viscometer; viscosities appropriate for different application methods vary considerably.
The aqueous coating composition is typically applied to a transparent, translucent, opaque, or pigmented substrate such as, for example, wood, metal, plastics, leather, glass, woven or nonwoven textiles, plaster, drywall, cementitious substrates such as, for example, concrete, stucco, and mortar, previously painted or primed surfaces, and weathered surfaces. The aqueous coating composition may be applied to a substrate using conventional coatings application methods such as, for example, brush, paint roller, curtain coater and spraying methods such as, for example, air-atomized spray, air-assisted spray, airless spray, high volume low pressure spray, and air-assisted airless spray.
Drying of the aqueous coating composition may be allowed to proceed under ambient conditions such as, for example, at 5° C. to 35° C. or the coating may be dried at elevated temperatures such as, for example, from 35° C. to 150° C.
Butyl acrylate BA
Allyl methacrylate ALMA
Methyl methacrylate MMA
Methacrylic acid MAA
Isoascorbic acid IAA
Sodium sulfoxylate formaldehyde SSF
DI water=deionized water
Sample Viscosity:
200 ml of each mixture was transferred to an 8 ounce graduated, wide mouth glass container (EMSCO cat#GLS00846). Determination of Brookfield viscosity (units of millipascal second) was made using a Brookfield viscometer (Model DV-I, Brookfield Engineering). Two viscosity points were determined using spindle number 1 or 2 at rotation rates of 3 RPM and 12 RPM. After equilibrating mixture for 16 hours, viscosity measurements were made at ambient temperature (23-26 C) after mixing by hand (for 20 seconds) using a wooden tongue depressor.
Heat Age (“HA”) Testing:
The 8 ounce glass containers were stored in a 60° C. oven for 10 days (un-disturbed). After 10 days the samples were removed from the oven, allowed to cool to ambient temperature (23-26° C.) and were assessed for syneresis and sedimentation.
Syneresis Assessment:
Syneresis is a separation between the aqueous and polymeric part of an emulsion and is indicated by the formation of a clear or a translucent layer on the top of the emulsion. The separation layer was measured in cm of layer at the top/cm of total mixture in the container.
Sedimentation and Hard Packing:
Prior to mixing the emulsion after heat aging, the bottom of the container was probed to determine the amount and type of sediment present. We noted the extent of sediment and the type of sediment (i.e soft pack or hard pack). For this assessment we used a rating scale of 1 to 5. A rating of 5 indicates no sedimentation was present in the mixture and a rating of 1 indicates significant sedimentation was found and that the sediment was hard packed.
Measurement of Particle Size.
Particle diameters of from 0.5 microns to 30 microns herein are those measured using a Disc Centrifuge Photosedimentometer (“DCP”) (CPS Instruments, Inc.) that separates modes by centrifugation and sedimentation through a sucrose gradient. The samples were prepared by adding 1-2 drops into 10 cc DI water containing 0.1% sodium lauryl sulfate.0.1 cc of the sample was injected into the spinning disc filled with 15 cc. sucrose gradient. Samples were analyzed relative to a polystyrene calibration standard. Specific conditions were: sucrose gradient 2-8%; disc speed 10,000 rpm; calibration standard was 895 nm diameter polystyrene.
Particle diameters of from greater than 30 microns to 150 microns herein are those measured using a Coulter counter (Beckman Coulter Multisizer 3 or 4). A 30-50 mmg sample was diluted in 8-10 ml. DI water. 3-6 drops of the diluted sample were added to 175 ml of Isotone II solution. The aperture was selected based on the particle diameter, generally from 2-60% of the particle diameter
Sample a. Formation of Seed Polymer for Use in Preparing Particulate Polymer
Unless otherwise noted, the terms “charged” or “added” indicate addition of all the mixture at once. The following mixtures were prepared:
A reactor equipped with stirrer and condenser and blanketed with nitrogen was charged with Mixture A and heated to 82° C. To the reactor contents was added 15% of Mixture B and 25% of Mixture C. The temperature was maintained at 82° C. and the reaction mixture was stirred for 1 hour, after which the remaining Mixture B and Mixture C were metered in to the reactor, with stirring, over a period of 90 minutes. Stirring was continued at 82° C. for 2 hours, after which the reactor contents were cooled to room temperature. The average diameter of the resulting emulsion particles was 0.2 micron, as measured by light scattering using a BI-90 Plus instrument from Brookhaven Instruments Company, 750 Blue Point Road, Holtsville, N.Y. 11742.
Weighed and added the DI water to the emulsion tank. Turned on emulsion tank agitator. Weighed and added the DS-4 to the emulsion tank and agitated for 2 min. Added BA. Added MMA. Added MAA. Agitated for 5 min. Checked for stable ME.
n-DDM Emulsion Preparation
In order to get a stable n-DDM emulsion it is necessary to shear the emulsion to very small droplets using a high speed mixer.
Charged 1236.7 g of DI water to a one gallon container. Charged 42.23 g of sodium dodecylbenzenesulfonate (23%) and 1067.4 g of n-DDM to the container in that order. Agitated the mixture until the mixture became very thick and creamy.
Charged the kettle water to the reactor and heated to 88-90° C. Started agitation and began a 30 min. nitrogen sparge. After 30 min turned off nitrogen sparge. Added buffer. Added kettle additive. Added kettle catalyst. Added Seed. With the kettle at 83-87° C. fed the ME over 240 minutes. Fed the n-DDM emulsion over 235 minutes. Fed the co-feed catalyst over 240 minutes. Controlled the temperature at 83-87° C. during feeds. When the n-DDM emulsion addition was complete, fed rinse over 5 min. When the ME and co-feed catalyst were complete, added rinses. Held the reactor at 83-87° C. for 15 min. Cooled to 70° C. Added chaser promoter and held 15 min. Added chase I and held 15 min at 70° C. Added chase II and held 15 min at 70° C. Added chase III and held 15 min at 70° C. Cooled to 40 C and filtered.
Added kettle charge to the reactor and heated to 78° C. Turned on agitation. Made up ME I as follows: Added surfactant and water to the ME tank. Slowly stirred in BA, added ALMA. At 78° C., added seed and rinsed water. Started ME I feed at 116.43 g/min. Did not let temperature fall below 63° C. When 1510 grams of ME I had been fed (20% of ME I) stopped ME I and held 30 min. Cooled to 65° C. While cooling made up the initiator emulsion. With the reactor at 65° C., added the initiator emulsion and watched for exotherm. After peak exotherm, allowed the reaction mixture temperature to increase to 83° C. over 10 min. while resuming ME I through CF equipped with rotor stator at 116.43 g/min. When ME I was complete, added rinse. Cooled to 78° C. Made up ME II in the order listed. At 78° C., added stage II promoter (pre-mixed before adding), started co-feed catalyst and activator at 9.5 g/min over 50 min. Started ME II at 37.7 g/min. over 45 min. Maintained 78° C. reaction temperature. When ME II and co-feeds were complete, added rinses. Cooled to 65° C. At 65° C., started chaser catalyst and activator at 8.60 g/min. over 40 min. When the chaser catalyst and activator were complete cooled to 25° C. Filtered to remove any agglomeration.
Sample B. Formation of Large Particle Size Polymer not within the Parameters of Particulate Polymer of this Invention
Added kettle charge to the reactor and heated to 78° C. and turned on agitation. Made up ME I as follows: Added surfactant and water to the ME tank. Slowly stirred in BA and ALMA. At 78° C., added seed and rinse water. Started ME I at 116.43 g/min. Did not let temperature go below 63° C. When 1510 grams of ME I had been fed (20% of ME I) stopped ME I and held 30 min. Cooled to 65° C. While cooling made up the initiator emulsion. With the reactor at 65° C. added the initiator emulsion and watched for exotherm. After peak exotherm, allowed the reaction mixture temperature to increase to 83° C. over 10 min. while resuming ME I feed. When ME I was complete, added rinse. Cooled to 78° C. Made up ME II in the order listed. At 78° C., added stage II promoter (pre-mixed before adding) started co-feed catalyst and activator at 9.49 g/min over 50 min. Started ME II at 37.7 g/min. over 45 min. Maintained 78° C. reaction temperature. When ME II and co-feeds were complete added rinses. Cooled to 65° C. At 65° C., started chaser catalyst and activator at 8.60 g/min. over 40 min. When the chaser catalyst and activator were complete cooled to 25° C. Filtered to remove any agglomeration.
Sample C. Formation of Large Particle Size Polymer not within the Parameters of Particulate Polymer of this Invention
Added kettle charge to the reactor and heated to 78° C. and turned on agitation. Made up ME I as follows: Added surfactant and water to the ME tank. Slowly stirred in BA and ALMA. At 78° C., added seed and rinse water. Started ME I at 116.43 g/min. Did not let temperature go below 63° C. When 1510 grams of ME I had been fed (20% of ME I) stopped ME I and held 30 min. Cooled to 65° C. While cooling, made up the initiator emulsion. With the reactor at 65° C. added the initiator emulsion and watched for exotherm. After peak exotherm, allowed the reaction mixture temperature to increase to 83° C. over 10 min. while resuming ME I feed. When ME I was complete, added rinse. Cooled to 78° C. Made up ME II in the order listed. At 78° C., added stage II promoter (pre-mixed before adding) started co-feed catalyst and activator at 9.49 g/min over 50 min. Started ME II at 37.7 g/min. over 45 min. Maintained 78° C. reaction temperature. When ME II and co-feeds were complete added rinses. Cooled to 65° C. At 65° C., started chaser catalyst and activator at 8.60 g/min. over 40 min. When the chaser catalyst and activator were complete cooled to 25° C. Filtered to remove any agglomeration.
Sample D. Formation of Large Particle Size Polymer not within the Parameters of Particulate Polymer of this Invention
Added kettle charge to the reactor and heated to 78° C. and turned on agitation. Made up ME I as follows: Added surfactant and water to the ME tank. Slowly stirred in BA and ALMA. At 78° C., added seed and rinse water. Started ME I at 116.43 g/min. Did not let temperature go below 63° C. When 1510 grams of ME I had been fed (20% of ME I) stopped ME I and held 30 min. Cooled to 65° C. While cooling made up the initiator emulsion. With the reactor at 65° C. added the initiator emulsion and watched for exotherm. After peak exotherm, allowed the reaction mixture temperature to increase to 83° C. over 10 min. while resuming ME I feed. When ME I was complete, added rinse. Cooled to 78° C. Made up ME II in the order listed. At 78° C., added stage II promoter (pre-mixed before adding) started co-feed catalyst and activator at 9.49 g/min over 50 min. Started ME II at 37.7 g/min. over 45 min. Maintained 78° C. reaction temperature. When ME II and co-feeds were complete added rinses. Cooled to 65° C. At 65° C., started chaser catalyst and activator at 8.60 g/min. over 40 min. When the chaser catalyst and activator were complete cooled to 25° C. Filtered to remove any agglomeration.
Aqueous compositions Example 1 and Comparative Examples A-C were prepared from Samples A-D, respectively using a 16 ounce plastic paint container. The materials, as detailed in Table 18.1, were added in the order provided while mixing using a 3 pitch blade mechanical mixer. After all materials were added the mixture was stirred fir 5 minutes. LAPONITE™ RD solution was prepared by adding 5.4 g LAPONITE™ RD to 194.6 g DI water and mixing for 1 hour prior to use.
The aqueous compositions, Examples 2-3, of the present invention provide improved sediment, syneresis relative to the corresponding aqueous compositions, Comparative Examples D-I.
The samples were prepared in an 8 ounce plastic paint container. The materials were added in the order provided while mixing using a 3 pitch blade mechanical mixer. After all materials were added the mixture was stirred for an additional 5 minutes. LAPONITE™ RD solution was prepared in advance by adding 5.4 g LAPONITE™ RD to 194.6 g DI water and mixing for 1 hour prior to use. The viscosity of the coatings were measured using a Krebs viscometer and are reported in Krebs units. After preparation, the samples were drawn down using a 3 mil bird applicator over a Penopec 1B chart (Leneta company). After drying for at least 16 hours at ambient conditions, gloss was measured in triplicate at 60 degree and 85 degree specular gloss using a Micro-TRI-Gloss meter (Byk-Gardner GmbH, catalogue number 4448).
| Number | Date | Country | |
|---|---|---|---|
| 61527153 | Aug 2011 | US |
