Description

Surface Active Adjuvant for Coatings

Technical Field

[0001] The present invention relates to a composition, notably a coating composition, which comprises : (A) an amide compound; (B) an ethylene oxide/propylene oxide copolymer; and (C) a latex polymer.

Background Art

[0002] Surfactants are widely used in waterborne formulations. Modern surfactants often have properties that are specifically tailored to the performance requirements of the particular application in which they are used.

[0003] Some industrial processes that utilize surfactants involve dynamic surface conditions in which the speed of new surface creation is high, for instance in applications such as printing, rolling coating, curtain coating, ink jetting, spraying coating, etc.. Such processes typically require that surfactants included in the applied formulation exhibit the ability to lower the surface tension efficiently, to wet the substrate rapidly, to facilitate the emulsification and/or dispersing, and so on. Dynamic surface tension (DST) is generally used to measure the capability of one solution to lower surface tension.

[0004] For example, US Patent No. 5,328,884 discloses a color developer composition which contains an amide compound as emulsifier/dispersant. However, it is known that surfactants tend to cause foaming, which is undesirable for certain applications. For example, high level of foaming in coating compositions would damage surface quality and functions of the coated layer. Also, during production of coating formulations, foaming generated by surfactants can harm process efficiency and product quality.

[0005] Polar organic solvents are also known to be useful for reducing surface tension of waterborne formulations. However, in general, high dosage of water soluble solvents is required to achieve low surface tension. Such high dosage of water soluble solvents can lead to high amount of VOC (volatile organic compound), which is a problem. In the case of water insoluble polar solvents, the water insoluble solvents often affect dispersion stability of the coating and cause poor miscibility of the coating.

[0006] There is a need to provide an adjuvant system which, at low dosage, is highly potent in reducing surface tension of aqueous compositions. There is a need to provide a coating composition which has low surface tension, combined with low foaming and good miscibility.

Summary of Invention

[0007] In one aspect, the present invention provides a composition which comprises (A) an amide compound, (B) an ethylene oxide/propylene oxide copolymer; and (C) a latex polymer.

[0008] The amide compound may be represented by the general formula:

RI-(C=0)-N(R ₂ )(R ₃ ) (I)

wherein Ri represents C ₄ -C22, saturated or unsaturated, linear or branched, aliphatic hydrocarbon group; and

R2 and R3 independently represent hydrogen, or a Ci-C ₄ , saturated or unsaturated, linear or branched, aliphatic hydrocarbon group.

[0009] In some embodiments, the amide compound is represented by the general formula:

R1-(C=0)-N(R ₂ )(R ₃ ) (II)

wherein R1 represents a C ₄ -C ₂ 2, saturated or unsaturated, linear or branched, aliphatic hydrocarbon group; and

R ₂ and R3 are methyl.

[0010] The composition of the invention is notably a coating composition, in particular an aqueous coating composition.

[0011] It has been surprisingly found that the composition provides low surface tension, leading to benefits, such as fast wetting, good dispersion and emulsification, good water resistance and satisfactory miscibility. The composition also provides low foaming.

Detailed Description

[0012] Throughout the description, including the claims, the term "comprising one" or“comprising a" should be understood as being synonymous with the term "comprising at least one", unless otherwise specified, and "between" should be understood as being inclusive of the limits.

[0013] It should be noted that in specifying any range of concentration, weight ratio or amount, any particular upper concentration, weight ratio or amount can be associated with any particular lower concentration, weight ratio or amount, respectively.

[0014] The articles“a”,“an” and“the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

[0015] The term“and/or” includes the meanings“and”,“or” and also all the other possible combinations of the elements connected to this term.

[0016] As used herein, the terminology "(C _n -C _m )" in reference to an organic group, wherein n and m are each integers, indicates that the group may contain from n carbon atoms to m carbon atoms per group.

[0017] As used herein, the term "hydrocarbon group" refers to a group mainly consisting of carbon atoms and hydrogen atoms, which group may be saturated or unsaturated, linear, branched or cyclic, aliphatic or aromatic.

[0018] As used herein, “aliphatic hydrocarbon group” refers to a straight or branched hydrocarbon chain, and optionally containing one to two sites of olefinic unsaturation or one or two sites of acetylenic unsaturation, such as alkyl and alkenyl.

[0019] "Alkyl", as used herein, means a group or part of a group which refers to a straight or branched saturated aliphatic hydrocarbon group. Examples of suitable alkyl include methyl, ethyl, n-propyl, 2-propyl, n-butyl, sec-butyl, t-butyl, hexyl, and the like.

[0020] As used herein, the term “latex” is in its conventional meaning, i.e. a dispersion of particulate polymer matter in an aqueous phase.

[0021] As used herein, the term“coating composition” includes and is not limited to latex binders, resins, glues, adhesives which include and are not limited to pressure sensitive adhesives, inks which include and are not limited to UV inks, conventional inks, hybrid inks, and water-based inks, sealants, cement compositions, coatings which include and are not limited to paints. [0022] Amide Compound

[0023] The amide compound according to the present invention is represented by the general formula:

RI-(C=0)-N(R ₂ )(R ₃ ) (I)

wherein Ri represents C ₄ -C22, saturated or unsaturated, linear or branched, aliphatic hydrocarbon group; and

R2 and R3 independently represent hydrogen, or a Ci-C ₄ , saturated or unsaturated, linear or branched, aliphatic hydrocarbon group.

[0024] In general formula (I), R1 is preferably a C ₄ -C2o aliphatic group, more preferably a C ₅ -C16 aliphatic hydrocarbon group, even more preferably a C6-C12 aliphatic hydrocarbon group, and most preferably a Cs-Cio aliphatic hydrocarbon group.

[0025] In particular, the amide compound is represented by the general formula:

R1-(C=0)-N(R ₂ )(R ₃ ) (II)

wherein R1 represents a C ₄ -C ₂ 2, saturated or unsaturated, linear or branched, aliphatic hydrocarbon group; and

R ₂ and R3 are methyl.

[0026] In general formula (II), R1 is preferably a C ₅ -C16 aliphatic hydrocarbon group, more preferably a C6-C12 aliphatic hydrocarbon group, even more preferably a Cs-Cio aliphatic hydrocarbon group.

[0027] Examples of the amide compound include and are not limited to N,N-di(2-ethylhexyl)fomnamide, N,N-dicyclohexylfomnamide,

N,N-diphenylfomnamide, N,N-dibutylacetamide, N,N-dioctylacetamide, N,N-di(2-ethylhexyl)acetamide, N-[3-(2-ethylhexyloxy)propyl]acetamide, N,N-di(2-ethylhexyl)propionamide, N,N-diethylcaprylamide,

N,N-dibutylcaprylamide, N,N-di(2-ethylhexyl)caprylamide,

N,N-dicyclohexylcaprylamide, N,N-dimethyllauroylamide,

N,N-diethyllauroylamide, N,N-dibutyllauroylamide,

N-(2-ethylhexyl)lauroylamide, N,N-di(2-ethylhexyl)lauroylamide,

N-lauryllauroylamide, N,N-diallyllauroylamide,

N,N-dicyclohexyllauroylamide, N,N-dimethylmyristoylamide,

N,N-diethylmyristoylamide, palmitoylamide, N,N-dimethylpalmitoylamide, N,N-diethylpalmitoylamide, stearoylamide, N,N-dimethylstearoylamide, N,N-diethylstearoylamide, oleoylamide, N,N-dimethyloleoylamide, N,N-diethyloleoylamide, N,N-dibutyloleoylamide, lauroylmorpholide, caprylmorpholide, oleoylmorpholide, N,N-di(2-ethylhexyl)acetamide,

N,N-dicyclohexylacetamide, N,N-diethyllauroylamide, N,N-dibutyllauroylamide, N,N-dimethyloleoylamide, N,N-diethyloleoylamide and N,N-dibutyloleoylamide, N,N-dioctylmethanesulfonamide, N,N-dicyclohexylmethanesulfonamide, N,N-dioctylethanesulfonamide, toluenesulfonamide, N-methyltoluenesulfonamide, N,N-dimethyltoluenesulfonamide, N-ethyltoluenesulfonamide, N,N-diethyltoluenesulfonamide, N-butyltoluenesulfonamide, N,N-dibutyltoluenesulfonamide, N-octyltoluenesulfonamide, N,N-dioctyltoluenesulfonamide, N-dodecyltoluenesulfonamide, N-(2-hydroxyethyl)toluenesulfonamide, N-(3-methoxypropyl)toluenesulfonamide,

N-(3-ethoxypropyl)toluenesulfonamide,

N-(3-octoxypropyl)toluenesulfonamide, N-(toluenesulfonyl)morpholine, N-(benzenesulfonyl)piperidine, xylenesulfonamide, N,N-dimethylxylenesulfonamide, N,N-diethylxylenesulfonamide, N,N-dibutylxylenesulfonamide, N-octylxylenesulfonamide, N,N-dibutyltoluenesulfonamide, N,N-dioctylmethanesulfonamide,

N-octylxylenesulfonamide, N,N-dimethyl hexamide, N,N-dimethyl octanamide, N,N-dimethyl decanamide, N,N-dimethyl dodecanamide, N,N-dimethyl decamide, N,N-dimethyl tetradecanamide, and the like.

[0028] The amide compound may be present in the amount of from 0.01 % to 5% based on the total weight of the composition, preferably from 0.05% to 3%, more preferably from 0.1 % to 1 %, still more preferably from 0.2% to 0.5%.

[0029] Ethylene Oxide/Propylene Oxide Copolymer

[0030] The ethylene oxide/propylene oxide copolymer may notably be selected from those ethylene oxide/propylene oxide block copolymers known to have surfactant behaviours. The ethylene oxide/propylene oxide copolymer may be represented by the general formula :

H0(CH ₂ CH ₂ 0) _m (CH ₂ CH(CH ₃ )0)nH (|||) wherein m and n, respectively, is an integer of from 1 to 300, preferably from 5 to 250, even more preferably from 10 to 200.

[0031] The ethylene oxide/propylene oxide copolymer may be represented by the general formula :

H0(CH2CH20) _m (CH2CH(CH ₃ )0)n(CH2CH ₂ 0) _m H (|V)

wherein m and n, respectively, is an integer of from 1 to 300, preferably from 5 to 250, even more preferably from 10 to 200.

[0032] The ethylene oxide/propylene oxide copolymer may also be represented by the general formula :

H0(CH2CH(CH ₃ )0)n(CH2CH20) _m (CH ₂ CH(CH ₃ )0)nH (V)

wherein m and n, respectively, is an integer of from 1 to 300, preferably from 5 to 250, even more preferably from 10 to 200.

[0033] Preferably, the ethylene oxide/propylene oxide copolymer has an HLB (Hydrophile-Lipophile Balance) value in the range of from 6 to 30, more preferably of from 6 to 18. HLB value of ethylene oxide and propylene oxide copolymers can typically be determined according to the method described in "Nonionic Surfactants", Surfactant Science Series Vol. 1 , Marcel Dekker Inc., (1967) p309.

[0034] Alternatively, the ethylene oxide/propylene oxide copolymer may be a compound represented by any one of general formulas :

H0(CH ₂ CH ₂ 0) _m (CH ₂ CH(CH3)0)nR ₄ (VI)

H0(CH2CH20) _m (CH2CH(CH ₃ )0)n(CH2CH ₂ 0) _m R4 (VII)

H0(CH2CH(CH ₃ )0)n(CH2CH20) _m (CH ₂ CH(CH ₃ )0)nR4 (VIII)

H0(CH2CH(CH ₃ )0)n(CH2CH ₂ 0) _m R4 (IX)

wherein m and n, respectively, is an integer of from 1 to 300, preferably from 5 to 250, even more preferably from 10 to 200; R ₄ is a C1-C18, saturated or unsaturated, linear or branched, aliphatic hydrocarbon group.

[0035] The ethylene oxide/propylene oxide copolymer may be present in the amount of from 0.01 % to 5% based on the total weight of the composition, preferably from 0.05% to 3%, more preferably from 0.1 % to 1 %, still more preferably from 0.2% to 0.5%. [0036] Latex Polymer

[0037] The latex polymer in included in the composition, notably as a binder. The latex polymer can be selected from pure acrylics (comprising acrylic acid, methacrylic acid, acrylate ester, and/or methacrylate ester as the main monomers); styrene acrylics (comprising styrene and acrylic acid, methacrylic acid, acrylate ester, and/or methacrylate ester as the main monomers); vinyl acetate-acrylic co-polymers (comprising vinyl acetate and one or more selected from acrylic acid, methacrylic acid, acrylate ester and methacrylate ester, as the main monomers); and vinyl acetate- ethylene-acrylic co-polymers (comprising ethylene, vinyl acetate, and one or more selected from acrylic acid, methacrylic acid, acrylate ester and methacrylate ester, as the main monomers).

[0038] The latex polymer may also be polyurethane, polyepoxy, polyester, polysiloxane, polymer from chrorinated alkenyl monomers, polymer from fluorinated alkenyl monomers, and co-polymer comprising 2 or more polymers mentioned above.

[0039] Preferably, the latex polymer is a pure acrylic polymer or a styrene acrylic copolymer.

[0040] According to any one of the invention embodiments, the typical monomers from which the latex polymer is formed may comprise at least one acrylic monomer selected from the group consisting of acrylic acid, acrylic acid esters, methacrylic acid, and methacrylic acid esters. In addition, the other monomers for making the latex polymer can optionally be selected from one or more monomers selected from the group consisting of styrene, a-methyl styrene, vinyl chloride, acrylonitrile, methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl esters of branched tertiary monocarboxylic acids (e.g. vinyl esters commercially available under the mark VEOVA from Shell Chemical Company or sold as EXXAR Neo Vinyl Esters by ExxonMobil Chemical Company), itaconic acid, crotonic acid, maleic acid, fumaric acid, and ethylene. It is also possible to include C ₄ -Cs conjugated dienes such as 1 ,3-butadiene, isoprene and chloroprene. Typically, the monomers include one or more monomers selected from the group consisting of n-butyl acrylate, methyl methacrylate, styrene and 2-ethylhexyl acrylate.

[0041] In some embodiments, the latex polymer is a vinyl acetate-acrylic co-polymer which is comprised of acrylic monomers and vinyl acetate monomers. The acrylic monomers can be any acrylic compound having acrylic functionality. Suitable acrylic unsaturated functional monomers include, but are not limited to esters of methacrylic acid including methyl methacrylate and butyl methacrylate, and esters of acrylic acid including ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate. Specific examples of acrylate monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, butyl methacrylate, iso-butyl methacrylate, iso-bornyl methacrylate hydroxyl ethyl acrylate and hydroxyl ethyl methacrylate. Suitable vinyl acetate monomers can be vinyl acetate, vinyl isopropyl acetate. The vinyl acetate- acrylic co-polymer suitable for the present invention may comprise a co-polymer containing 10 to 30 percent by weight an acrylic monomer and about 70 to 90 percent a vinyl acetate monomer.

[0042] The vinyl acetate-acrylic co-polymer may comprises one or more additional monomers including ethylenically unsaturated monomers which can be copolymerized with vinyl acetate and/or acrylic compounds, such as vinyl ether, acrylamide, acrylonitrile and unsaturated carboxylic acid.

[0043] In some embodiments, the latex polymer is a vinyl acetate-ethylene-acrylic co-polymer which is comprised of ethylene and vinyl acetate, and unsaturated co-monomer of any acrylic compound having acrylic functionality. The amount of ethylene monomer used to prepare the vinyl acetate-ethylene-acrylic co-polymer may be from about 5 wt% to about 25 wt%, based on the total weight of monomers used to prepare the vinyl acetate-ethylene-acrylic co-polymer. The amount of vinyl acetate used to prepare the vinyl acetate-ethylene-acrylic co-polymer may be from about 75 wt% to about 95 wt%, based on the total weight of monomers used to prepare the vinyl acetate-ethylene-acrylic co-polymer. The vinyl acetate- ethylene-acrylic co-polymer may further comprise one or more optional unsaturated co-monomers. Such optional co-monomers can include, for example, C1-C12 esters of (meth)acrylic acid.

[0044] The latex polymer dispersion typically includes from about 30 to about 75% solids and a mean latex particle size of from about 70 to about 650 nm. In another embodiment, the latex polymer of the present invention has a mean particle size of less than about 400nm, typically a mean particle size of less than about 200 nm, more typically a mean particle size of less than about 190 nm, and most typically a mean particle size of less than about 175 nm. In another embodiment, the polymer has a mean particle size of from about 75 nm to about 400 nm.

[0045] The latex polymer is typically present in the composition in an amount from about 5 to about 60 percent by weight, and more typically from about 8 to about 40 percent by weight (i.e. the weight percentage of the dry latex polymer based on the total weight of the composition).

[0046] In some embodiments, the composition of the invention comprises (A) an amide compound; (B) an ethylene oxide/propylene oxide copolymer; and (C) a latex polymer;

wherein the amide compound is represented by the general formula: R1-(C=0)-N(R ₂ )(R ₃ ) (II)

wherein R1 represents a C ₄ -C22, saturated or unsaturated, linear or branched, aliphatic hydrocarbon group;

R2 and R3 are methyl.

[0047] In some embodiments, the composition of the invention comprises (A) an amide compound; (B) an ethylene oxide/propylene oxide copolymer; and (C) a pure acrylic polymer or a styrene acrylic copolymer;

wherein the amide compound is represented by the general formula: R1-(C=0)-N(R ₂ )(R ₃ ) (II)

wherein R1 represents a C ₄ -C ₂ 2, saturated or unsaturated, linear or branched, aliphatic hydrocarbon group;

R ₂ and R3 are methyl.

[0048] The weight ratio of the amide compound and the ethylene oxide/propylene oxide copolymer is preferably in the range of from 40/60 to 95/5, more preferably from 50/50 to 80/20. [0049] The composition of the invention may further comprise water and/or an organic solvent, such as alcohols, formamides, acetamides, glycols, glycolethers, diglymes, glycoletheracetates and ketones. Examples of the organic solvent include: methanol, ethanol, 2-propanol, 1-propanol, butanol, hexanol, 2-ethylhexanol, DMF, DMAC, EG, PG, glycerol, DEG, TEG, hexyleneglycol, alkylcellosolve, alkylcarbitol, PEG monoalkylethers, methylglyme, ethylglyme, ethylenglycolmonomethlyether acetate, acetone, MEK.

[0050] The composition typically includes at least one pigment. The term "pigment" as used herein includes non-film-forming solids such as pigments, extenders, and fillers. The at least one pigment is typically selected from the group consisting of T1O2 (in both anastase and rutile forms), clay (aluminum silicate), CaC03 (in both ground and precipitated forms), aluminum oxide, silicon dioxide, magnesium oxide, talc (magnesium silicate), barytes (barium sulfate), zinc oxide, zinc sulfite, sodium oxide, potassium oxide and mixtures thereof. Suitable mixtures include blends of metal oxides such as those sold under the marks MINEX (oxides of silicon, aluminum, sodium and potassium commercially available from Unimin Specialty Minerals), CELITES (aluminum oxide and silicon dioxide commercially available from Celite Company), ATOMITES (commercially available from English China Clay International), and ATTAGELS (commercially available from Engelhard). More typically, the at least one pigment includes T1O2, CaC03 or clay. Generally, the mean particle sizes of the pigments range from about 0.01 to about 50 microns. For example, the T1O2 particles used in the aqueous coating composition typically have a mean particle size of from about 0.15 to about 0.40 microns. The pigment can be added to the aqueous coating composition as a powder or in slurry form. The pigment is typically present in the aqueous coating composition in an amount from about 5 to about 50 percent by weight, more typically from about 10 to about 40 percent by weight.

[0051] The composition can optionally contain additives such as one or more film- forming aids or coalescing agents. Suitable film-forming aids or coalescing agents include plasticizers and drying retarders such as high boiling point polar solvents. Other conventional coating additives such as, for example, dispersants, additional surfactants (i.e. wetting agents), rheology modifiers, defoamers, thickeners, biocides, mildewcides, colorants such as colored pigments and dyes, waxes, perfumes, co-solvents, and the like, can also be used in accordance with the invention.

[0052] In some embodiments, the composition can include less than 2.0% of VOC agents based on the total weight of the aqueous coating composition. Exemplary agents include ethylene glycol, diethylene glycol, propylene glycol, glycerol (1 ,2,3-trihydroxypropane), ethanol, methanol, 1-methoxy-2-propanol, 2-amino-2-methyl-1 -propanol, and FTS-365 (a freeze-thaw stabilizer from Inovachem Specialty Chemicals).

[0053] The balance of the composition of the invention is water. Although much of the water is present in the polymer latex dispersion and in other components of the composition, water is generally also added separately to the composition. Typically, the composition includes from about 10% to about 85% by weight and more typically from about 35% to about 80% by weight water. Stated differently, the total solids content of the composition is typically from about 15% to about 90%, more typically, from about 20% to about 65%.

[0054] The composition of the invention is notably a coating composition, in particular an aqueous coating composition. The composition may be an aqueous solution or dispersion, an oil-in-water emulsion, a water-in-oil emulsion, an oil-water-oil emulsion, a water-oil-water emulsion, an oily solution, an alcoholic solution, and the like.

[0055] The composition of the present invention can be prepared by a process comprising the step of mixing the surfactants and polymers described herein with water, optionally with the additional ingredients and organic solvents described herein. The mixing can be done by any mean well known to a skilled person. [0056] The present invention will be explained in greater details through Examples and Comparative Examples, but the present invention is not to be construed as being limited thereto.

Examples

[0057] Latex preparation

[0058] The acrylic latex used was Saibinol CA-200 obtained from Saiden Chemical. The styrene acrylic latex used was prepared by using the following procedure: in a four-necked separable glass reactor with circulation jacket, 117g of distilled water and 0.6g of anionic reactive surfactant, 2-allyloxy-1 -alkyl(Cio-i ₄ )oxy-3-polyethoxylated propane ammonium sulfate ester, were charged and heated up to 80°C. 5% of monomer pre-emulsion which was prepared by mixing 80g of styrene, 80g of methylmethacrylate, 80g of 2-ethylhexylmethacrylate, 1.2g of acrylic acid, 2.35g of anionic reactive surfactant, 2-allyloxy-1- alkyl(Cio-i ₄ )oxy-3-polyethoxylated propane ammonium sulfate ester, and 138g of water at high speed stirring were added to the reactor. After the mixture reached 80 °C, 7.5g of 2% aqueous solution of ammonium persulfate were charged and kept for 15 minutes before start feeding 95% of the monomer pre-emulsion over 3 hours. While feeding monomer pre-emulsion, 22.5g of 2% ammonium persulfate aqueous solution were also co-feeded over 3 hours. After feeding monomer pre-emulsion and another 30 minutes at 80 °C, 0.5g of 70% tert-butylhydroperoxide was gradually added to the reactor followed by feeding 5g of 6% isoascorbic acid aqueous solution over 10 minutes. After keeping reaction at 80°C for 30 minutes, the reaction mix was cooled down to below 35°C and neutralized by 1.18g of 28% ammonium hydroxide solution to get 45% non-volatile styrene acrylic latex with pH=8.5.

[0059] Miscibility evaluation

[0060] Aqueous coating compositions were prepared by mixing the ingredients with distilled water. The compositions were stirred with a magnetic stirrer for 1 hour under 25°C. The visual appearance was then observed by eyes. When the miscibility is poor, one can observe small gel-like particles on surface of the liquid or on the wall of the container.

[0061] “G” means good miscibility and“P” means poor miscibility in the tables below.

[0062] Dynamic surface tension measurement

[0063] Dynamic surface tension measurement was carried out with bubble pressure tensiometer Krilss BP-50. The steps were conducted according to the manual of the equipment. Typically, the aqueous coating compositions prepared were stirred for 1 hour at 25°C. Then the compositions were subject to dynamic surface tension measurement at 25°C. Surface tension was measured at surface age (also referred to as“bubble life time”) = 0.03, 0.3 and 3 seconds, respectively.

[0064] Foaming tests

[0065] Foaming was evaluated by measuring height of the liquid including foam in the vial. In 50ml tall vial, 20g of the aqueous coating compositions were added. The compositions were foamed by shaking the vial upside down 1/sec for 1 min. Foam height was then calculated by formula : (Foam height) = (Liquid height including foam) - (Liquid height before shaking) (mm). Foam height was measured at 5 min after shaking.

[0066]

Table 1

Table 2

[0067] As shown in Tables 1 and 2, the formulations according to the present invention exhibited good miscibility, low surface tension and low foaming. “EX” means Example and “CE” means Comparative Example.