CA2199793A1 - Self-crosslinking coating formulation - Google Patents
Self-crosslinking coating formulationInfo
- Publication number
- CA2199793A1 CA2199793A1 CA002199793A CA2199793A CA2199793A1 CA 2199793 A1 CA2199793 A1 CA 2199793A1 CA 002199793 A CA002199793 A CA 002199793A CA 2199793 A CA2199793 A CA 2199793A CA 2199793 A1 CA2199793 A1 CA 2199793A1
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- water
- monomers
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- coating composition
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Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D153/00—Coating compositions based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers
- C09D153/02—Vinyl aromatic monomers and conjugated dienes
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D125/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Coating compositions based on derivatives of such polymers
- C09D125/02—Homopolymers or copolymers of hydrocarbons
- C09D125/04—Homopolymers or copolymers of styrene
- C09D125/08—Copolymers of styrene
- C09D125/14—Copolymers of styrene with unsaturated esters
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
- C09D133/04—Homopolymers or copolymers of esters
- C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09D133/062—Copolymers with monomers not covered by C09D133/06
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Paints Or Removers (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
This invention relates to the synthesis of a latex which can be used in making water-reducible self-crosslinking coating compositions, such as paints, which contain no or extremely low levels of volatile organic compounds. Coatings which are formulated with the latex of this invention offer an environmental advantage as well as excellent solvent resistance, excellent flexibility and excellent ultra-violet light resistance. This invention more specifically discloses a water-reducible coating composition which is comprised of (1) water; (2) a resin having repeat units which are derived from (a) about 30 to about 75 weight percent vinyl aromatic monomers, (b) about 20 to about 65 weight percent of alkyl acrylate monomers, (c) about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers, based on 100 weight percent monomers; (3) a wetting agent; and (4) a defoamer. Gamma-methacryloxypropyltrimethoxysilane is a representative example of a highly preferred acryloxyalkenyl-trialkoxysilane monomer.
Description
Q ~ 7 9 3 SELF-CROSSLINKING COATING FORMULATION
Background of the Invention Most conventional coating resins are insoluble in water. Therefore, in general practice, they have been dissolved in a suitable organic solvent or dispersed in water with the aid of an emulsifying agent or surfactant in order to provide a coating composition suitable for application to a substrate surface. A
serious disadvantage of organic solvent solutions is that they are potentially toxic, flammable and environmental pollutants. Water-reducible coatings greatly reduce the magnitude of these problems. For this reason, water-based paints are currently being used as a replacement for oil-based paints in many applications.
Various water-reducible coating resins, such as the one described in U.S. Patent No. 4,474,926, have been developed. Water-reducible coatings which utilize such resins have been developed for a variety of purposes and have been widely accepted in many applications such as highway striping paint.
United States Patent 4,968,741 describes a coating for metal substrates which provides improved corrosion and rust resistance. Such coatings are of the water-reducible type and can be beneficially utilized in the automotive industry and other applications where good rust resistance is needed.
For instance, such coatings are excellent for coating bridges and other outdoor metal structures.
It is also critical for coatings made with water-reducible coating formulations to offer the desired combination of physical and chemical properties. For instance, in many applications, it is important for the coating to exhibit excellent flexibility, excellent ultra-violet light resistance and excellent solvent resistance. In applications which involve metal substrates, outstanding corrosion and rust-resistance is normally also sought.
For purposes of this patent application, an aqueous coating system is considered to be a colloidal dispersion of a resin in water which can be reduced by the addition of water and which forms a durable coating when applied to a substrate surface. The term aqueous coating system is used herein interchangeably with the term water-reducible coating. Other names which are sometimes applied to water-reducible coatings are water-born, water-solubilized and water-dilutable.
Summary of the Invention This invention relates to the synthesis of a latex which can be used in making self-crosslinking water-reducible coating compositions, such as paints, which offer excellent solvent resistance, reduced drying time and improved adhesion to metal and glass.
Coatings which are formulated with the latex of this invention are environmentally advantageous because they contain no or extremely low levels of volatile organic compounds and additionally offer excellent flexibility and excellent ultra-violet light resistance.
The present invention more specifically discloses a water-reducible coating composition which is comprised of (1) water; (2) a resin having repeat units which are derived from (a) about 30 to about 75 weight percent vinyl aromatic monomers, (b) about 20 to about 65 weight percent of alkyl acrylate monomers, (c) about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers, based on 100 weight percent monomers; (3) a wetting agent;
and (4) a defoamer.
The subject invention further reveals a process for producing a neutralized latex that is useful in the manufacture of self-crosslinkable water-reducible coatings which comprises: (1) free radical aqueous emulsion polymerizing at a pH of less than about 3.5, a monomer mixture which comprises, based on 100 weight percent monomers: (a) from about 30 to about 75 weight percent vinyl aromatic monomers, (b) from about 20 to about 65 weight percent of alkyl acrylate monomers, (c) from about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers; in the presence of about 0.2 to 3 phm of at least one ~-olefin sulfonate soap to produce a latex;
and (2) neutralizing the latex with ammonia to a pH
which is within the range of about 7 to about 10.5 to produce the neutralized latex.
The present invention also discloses a latex which is useful in the manufacture of self-crosslinkable water-reducible coatings, said latex being comprised of (1) water, (2) an emulsifier and (3) a polymer which is comprised of repeat units which are derived from (a) about 30 to about 75 weight percent vinyl aromatic monomers, (b) about 20 to about 65 weight percent of alkyl acrylate monomers, (c) about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers.
Detailed Description of the Invention The latices of this invention are prepared by free radical emulsion polymerization. The charge compositions used in the preparation of the latices of this invention contain monomers, at least one ~-olefin 0~97g3 sulfonate surfactant, and at least one free radical initiator. The monomer charge composition used in such polymerizations is comprised of ~a) from about 30 to about 75 weight percent vinyl aromatic monomers, (b) from about 20 to about 65 weight percent of alkyl acrylate monomers, (c) from about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers.
It is preferred for the polymer being synthesized to be comprised of from about 40 weight percent to about 70 weight percent vinyl aromatic monomers, from about 25 weight percent to about 55 weight percent alkyl acrylate monomers, from about 1.5 weight percent to about 5 weight percent alkyl propenoic acid monomers and from about 1 weight percent to about 3 weight percent acryloxyalkenyltrialkoxysilane monomers. It is more preferred for the polymer to be comprised of from about 63 weight percent to about 67 weight percent vinyl aromatic monomers, from about 27 weight percent to about 31 weight percent alkyl acrylate monomers, from about 2 weight percent to about 4 weight percent alkyl propenoic acid monomers and from about 1.5 weight percent to about 2 weight percent acryloxyalkenyltrialkoxysilane monomers.
Some representative examples of vinyl aromatic monomers which can be used include styrene, alpha-methyl styrene and vinyl toluene. Styrene and alpha-methyl styrene are the preferred vinyl aromatic monomers. Due to its relatively low cost, styrene is the most preferred vinyl aromatic monomer.
The alkyl acrylate monomers which can be employed have alkyl moieties which contain from 2 to about 10 carbon atoms. The alkyl acrylate monomer will preferably have an alkyl moiety which contains from 3 ~ 2~7~ 3 to 5 carbon atoms. Normal-butyl acrylate is a highly preferred alkyl acrylate monomer.
The alkyl propenoic acid monomers that can be used have the structural formula:
R
CH2=C-COOH
wherein R represents a hydrogen atom or an alkyl group cont~;n;ng from 1 to 4 carbon atoms. The R group can accordingly be represented by the formula -CnH
wherein n is an integer from 0 to 4. Some representative examples of alkyl propenoic acid monomers which can be used include: acrylic acid, methacrylic acid (2-methylpropenoic acid), 2-ethylpropenoic acid, 2-propylpropenoic acid and 2-butylpropenoic acid. The preferred alkyl propenoic acid monomers are acrylic acid and methacrylic acid.
In most cases, it is advantageous to use a combination of both acrylic acid and methacrylic acid as the unsaturated carbonyl compound component used in making the latex. For instance, the utilization of about 1 to about 3 weight percent acrylic acid with about 0.5 to about 1.5 weight percent methacrylic acid results in the latex having improved freeze-thaw stability. For example, the utilization of about 2 percent acrylic acid with 1 percent methacrylic acid as the unsaturated carbonyl compound component results in the latex produced being capable of withst~nA;ng more than five (5) freeze-thaw cycles. It is important for latices which are shipped through cold regions of the world to have this improved freeze-thaw stability.
The acryloxyalkenyltrialkoxysilane monomers which can be used are of the structural formula:
7 ~ ~
~C,H2 ~o - R2 Rl--C-C-o~CH2~Si-o-R3 O o R4 wherein Rl represents a hydrogen atom, a methyl group (-CH3) or an ethyl group (-CH2-CH3), wherein n represents an integer from O to 10 and wherein R2, R3 and R4 can be the same or different and are selected from alkyl groups which contains from 1 to 3 carbon atoms. It is preferred for R1 to be a hydrogen atom or a methyl group. It is most preferred from Rl to be a methyl group. It is preferred for n to represent an integer from 2 to 4 with it being most preferred for n to represent 3. It is preferred for R2, R3 and R4 to represent methyl groups or ethyl groups with methyl groups being most preferred. Gamma-methacryloxypropyltrimethoxysilane which has the structural formula:
~C~H2 ~O-CH3 CH3-C-C-O-~CH2 ~ Si-O-CH3 o O-CH3 is the most highly preferred acryloxyalkenyl-trialkoxysilane monomer.
The charge composition used in the preparation of the latices of this invention will contain a substantial quantity of water. The ratio between the total amount of monomers present in the charge composition and water can range between about 0.2:1 and about 1.2:1. It is generally preferred for the ratio of monomers to water in the charge composition to be within the range of about 0.8:1 and about 1.1:1.
For instance, it is very satisfactory to utilize a ratio of monomers to water in the charge composition of about 1:1.
i~2~9~ 3 The charge composition will also contain from about 0.2 phm (parts per hundred parts of monomer) to about 3 phm of at least one ~-olefin sulfonate soap.
It is normally preferred for the ~-olefin sulfonate surfactant to be present in the polymerization medium at a level within the range of about 0.4 phm to about 2 phm. It is generally more preferred for the charge composition to contain from about 0.5 phm to about 1 phm of the ~-olefin sulfonate soap.
The use of larger amounts of the ~-olefin sulfonate soap in the polymerization medium leads to better latex stability. However, the utilization of larger amounts of surfactant also leads to greater blushing in the ultimate coating and consequently less rust and corrosion resistance.
The free radical aqueous emulsion polymerizations used in preparing the latices of this invention are initiated with at least one free radical generator.
The free radical generator is normally employed at a concentration within the range of about 0.01 phm to about 1 phm. The free radical initiators which are commonly used include the various peroxygen compounds such as potassium persulfate, ammonium persulfate, benzoyl peroxide, hydrogen peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, decanoyl peroxide, lauryl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, t-butyl hydroperoxide, acetyl peroxide, methyl ethyl ketone peroxide, succinic acid peroxide, dicetyl peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroxymaleic acid, t-butyl peroxybenzoate, acetyl cyclohexyl sulfonyl peroxide and the like; the various azo compounds such as 2-t-butylazo-2-cyanopropane, dimethyl azodiisobutyrate, azodiisobutylronitrile, 2-t-butylazo-1-cyanocyclohexane, 1-t-amylazo-1-cyanocyclohexane and the like, the ~99~ 3 various alkyl perketals, such as 2,2-bis-(t-butyl-peroxy)butane and the like. Water-soluble peroxygen-free radical initiators are especially useful in such aqueous polymerizations.
The emulsion polymerizations of this invention are typically carried out at the temperature ranging between about 125~F (52~C) and 190~F (88~C). At temperatures above about 190~F (88~C), alkyl acrylate monomers, such as butyl acrylate, have a tendency to boil. Thus, a pressurized jacket would be required for heating such alkyl acrylate monomers to temperatures in excess of about 88~C. On the other hand, the polymerization reaction proceeds at a very slow rate at temperatures below about 125~F (52~C).
The slow rate of polymerization experienced at temperatures below about 125~F (52~C) results in the polymer having a nonuniform distribution of repeat units in its backbone. The slow rates of polymerization experienced at such low temperatures are also undesirable because they greatly reduce the throughput of the polymerization reactor.
It is generally preferred for the polymerization temperature to be maintained within the range of about 150~F (66~C) to 180~F (82~C). It is generally more preferred for the reaction temperature to be controlled within the range of about 160~F (71~C) to about 170 F (77 C). It is important for the polymerization to be conducted at a pH which is below about 3.5 so that a water-sensitive polymer is not produced. It is preferred for the pH of the polymerization medium to be maintained at a level of about 3.0 or less throughout the polymerization. As the polymerization proceeds, the pH of the polymerization medium will drop naturally. Thus, good results can be attained by ad~usting the pH of the initial monomer charge composition to within the range 7 ~ ~
g of about 3.0 to about 3.5 and allowing the polymerization to proceed. In such a case, the final pH of the polymerization medium will be about l.5 which is highly satisfactory.
In commercial operations, it is typically desirable to add about 15 percent to about 25 percent of the monomers in an initial charge. The initial charge is then allowed to react for a period of about 30 minutes to about 60 minutes. Then the balance of the monomers to be charged can be continuously charged into the reaction zone at a rate which is sufficient to maintain a reaction temperature within the desired temperature range. By continuously adding the monomers to the reaction medium while maint~;n1ng a relatively constant reaction temperature, very uniform polymers can be prepared.
In accordance with the process of this invention, the latex synthesized is then neutralized with ammonia to a pH within the range of about 7 to about lO.5. It is normally preferred for the latex to be neutralized to a pH within the range of 8 to lO and more preferred for the latex to be neutralized to a pH within the range of about 9.0 to about 9.5. This can be accomplished by simply dispersing ammonia throughout the latex to produce neutralized latex. The ammonia will normally be in the form of ammonium hydroxide.
The latex formed can be diluted with additional water to the concentration (solids content) that is desired. This latex can be used in the preparation of water-reducible coatings using techniques well-known to those skilled in the art. Generally, various pigments and plasticizers are added to the latex in the preparation of the water-reducible coating. Poor adhesion is a problem that is sometimes encountered with water-reducible resins. The adhesion of coatings made with water-reducible resins to substrates can be greatly improved by the addition of a plasticizer.
A film-forming, water-reducible composition, such as a paint, can be prepared by mixing the latex, one or more pigments and a plasticizer. It is not necessary to include a coalescing solvent in the film-forming, water-reducible formulation. For environmental reasons, it is preferred not to include a coalescing solvent in the formulation. However, a small amount (0 to about 50 grams per liter) of coalescing solvent can be included. In cases where a coalescing solvent is employed, it is preferable for it to be at least water-miscible and even more preferable for it to be water-soluble. Of the various coalescing solvents generally ester-alcohols, such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, are preferred.
It should be noted that the pigment, plasticizer and optionally the coalescing solvent can be mixed directly with the resin in its water emulsion or latex. In such an operation, the composite would automatically be in a water-reduced form when sufficient ammonia is used.
Paint formulations can be made utilizing the latices of this invention. Such paint formulations are comprised of one or more pigments and the latex (water, emulsifier system and resin). Such paints can optionally contain fillers, plasticizers, stabilizers, defoamers, dryers, fungicides, insecticides, antifouling agents and anticorrosive agents.
Pigments are normally added to paint formulations to impart color and hiding power to the coating.
Titanium dioxide is an example of a widely-used pigment which imparts hiding power and a white color.
Mineral pigments, such as oxides of iron and chromium, organic pigments, such as phthalocyanine, and active anticorrosive pigments, such as zinc phosphate, are representative examples of other widely-used pigments.
Fillers are normally inexpensive materials which are added to the paint formulation to attain the desired consistency and non-settling characteristics.
Fillers can also improve the physical properties of coatings, such as resistance to cracking and abrasion.
Some representative examples of widely utilized fillers include chalks, clays, micas, forms of barites and talcs, and silica.
Driers are chemical compounds, such as salts of cobalt, lead, manganese, barium and zinc, which speed up drying. Stabilizers are chemical agents which neutralize the destructive effects of heat and ultraviolet light. Fungicides and insecticides are commonly added to interior and exterior house paints.
Antifouling compounds are commonly added to marine paints to inhibit marine growth. Plasticizers are agents which control the hardness of the film or which impart flexibility.
Of the various plasticizers, it is desired that one be selected which is liquid at room temperature such as 25~C and have a sufficiently high boiling point, preferably at least 100~C, and even more preferably, at least 150~C, so that they do not volatilize from the coating composition when applied to a substrate. Plasticizers which contain multiple hydroxyl groups should be avoided because their use can lead to instability. The plasticizer should enhance the water insolubility of a dried coating of the coalesced resin. Further, the plasticizer, or mixture of plasticizers, must be characterized by being compatible with the resin itself. For this characterization, a solubility parameter in the range of about 8 to about 16 is required. Such solubility parameter is of the type described in The Encyclopedia - 12 - ~ 7 ~ ~
of Polymer Science and Technology, Volume 3, Page 854, 1965, John Wiley and Sons, Inc., which is simply determined by the equation 6 = ( ~ ~ ) /v = F/MW/d where ~ = solubility parameter F = sum of the pertinent molar attraction constants of groups determined by Small, P A [(J Appl Chem 3, 71, (1953)]
V = Molar volume at 25~C
MW = molecular weight d = density at 25~C
Various plasticizers can be used for this purpose. They can, for example, be of the type listed in the Federation Series on Coatings Technology, Unit Twenty-two, entitled "Plasticizers," published April 1974, so long as they fulfill the melting point, boiling point and compatibility requirements. Some representative examples of preferred plasticizers include: butyl benzyl phthalate, blends of diethyleneglycol dibenzoate and dipropylene glycol dibenzoate, and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate.
Representative of various plasticizers are cyclic plasticizers such as phosphoric acid esters, phthalic anhydride esters and trimellitic acid esters as well as N-cyclohexyl-p-toluene sulfonamide, dibenzyl sebacate, diethylene glycol dibenzoate, di-t-octylphenylether, dipropane diol dibenzoate, N-ethyl-p-toluene sulfonamide, isopropylidenediphenoxypropanol, alkylated naphthalene, polyethylene glycol dibenzoate, o-p-toluene sulfonamide, trimethylpentanediol dibenzoate and trimethylpentanediol monoisobutyrate monobenzoate.
Representative of various acyclic plasticizers are adipic acid esters, azelaic acid esters, citric acid esters, acetylcitric acid esters, myristic acid esters, phosphoric acid esters, ricinoleic acid esters, acetylricinoleic acid esters, sebacic acid esters, stearic acid esters, epoxidized esters, as well as 1,4-butane diol dicaprylate, butoxyethyl pelargonate di[(butoxyethoxy)ethoxy] methane, dibutyl tartrate, diethylene glycol dipelargonate, diisooctyl diglycolate, isodecyl nonanoate, tetraethylene glycol di(2-ethylbutyrate), triethylene glycol di(2-ethyl-hexanoate), triethylene glycol dipelargonate and 2,2,4-trimethyl-1,3-pentane diol diisobutyrate.
Additional various plasticizers, cyclic, acyclic, and otherwise, include chlorinated paraffins, hydrogenated terphenyls, substituted phenols, propylene glycols, polypropylene glycol esters, polyethylene glycol esters, melamines, epoxidized soys, oils, melamines, liquid, hydrogenated abietate esters, epoxytallate esters, alkyl phthalyl alkyl glycolates, sulfonamides, sebacate esters, aromatic epoxies, aliphatic epoxies, liquid poly(~-methyl styrene), maleate esters, mellitate esters, benzoates, benzyl esters, tartrates, succinates, isophthalates, orthophthalates, butyrates, fumarates, glutarates, dicaprylates, dibenzoates and dibenzyl esters. It is to be appreciated that relatively low molecular weight polymers and copolymers derived from monoolefins containing 4 to 6 carbon atoms, mixtures of diolefins and monoolefins containing 4 to 6 carbon atoms as well as such hydrocarbons and hydrocarbon mixtures with styrene and/or ~-methyl styrene can also be used.
The preferred esters are prepared from the reaction of carboxylic and dicarboxylic acids including fatty acids, such as the phthalic acids, benzoic acid, dibenzoic acid, adipic acid, sebacic acid, stearic acid, maleic acid, tartaric acid, succinic acid, butyric acid, fumaric acid and glutaric acid with hydrocarbon diols, preferably saturated hydrocarbon diols, having about 7 to 13 carbon atoms.
Representative of various phosphoric acid esters are cresyl diphenyl phosphate, tricresyl phosphate, dibutyl phenyl phosphate, diphenyl octyl phosphate, methyl diphenyl phosphate, tributyl phosphate, triphenyl phosphate, tri(2-butoxyethyl) phosphate, tri(2-chloroethyl) phosphate, tri-2(chloropropyl) phosphate and trioctyl phosphate.
Representative of various phthalic anhydride esters are butyl octyl phthalate, butyl 2-ethylhexyl phthalate, butyl n-octyl phthalate, dibutyl phthalate, diethyl phthalate, diisodecyl phthalate, dimethyl phthalate dioctyl phthalates, di(2-ethylhexyl) phthalate, diisooctyl phthalate, di-tridecyl phthalate, n-hexyl n-decyl phthalate, n-octyl n-decyl phthalate, alkyl benzyl phthalate, bis(4-methyl-1,2-pentyl) phthalate, butyl benzyl phthalate, butyl cyclohexyl phthalate, di(2-butoxyethyl) phthalate, dicyclohexyl isodecyl phthalate, dicyclohexyl phthalate, diethyl isophthalate, di n-heptyl phthalate, dihexyl phthalate, diisononyl phthalate, di(2-methoxyethyl) phthalate, dimethyl isophthalate, dinonyl phthalate, dioctyl phthalates, dicapryl phthalate, di(2-ethylhexyl) isophthalate, mixed dioctyl phthalates, diphenyl phthalate, 2-(ethylhexyl) isobutyl phthalate, butyl phthalyl butyl glycolate, ethyl (and methyl) phthalyl ethyl glycolate, polypropylene glycol bis(amyl) phthalate, hexyl isodecyl phthalate, isodecyl tridecyl phthalate and isooctyl isodecyl phthalate.
Representative of trimellitic acid esters are triisooctyl trimellitate, tri-n-octyl n-decyl trimellitate, trioctyl trimellitate, tri(2-ethylhexyl) 7 ~ ~
trimellitate, tri-n-hexyl n-decyl trimellitate, tri-n-hexyl trimellitate, triisodecyl trimellitate and triisononyl trimellitate.
Representative of various adipic acid esters are di[2-(2-butoxyethoxy) ethyl] adipate, di(2-ethylhexyl) adipate, diisodecyl adipate, dioctyl adipates (including diisooctyl adipate) n-hexyl n-decyl adipate, n-octyl n-decyl adipate and di-n-heptyl adipate.
Representative examples of sebacic acid esters are dibutyl sebacate, di(2-ethylhexyl) sebacate, dibutoxyethyl sebacate, diisooctyl sebacate and diisopropyl sebacate.
Representative examples of azelaic acid esters are di(2-ethylhexyl) acelate dicyclohexyl acelate, diisobutyl azelate and diisooctyl azelate. In the practice of this invention, the water-reducible composition of resin, plasticizer and coalescing solvent, if used, is water-reduced by neutralizing the carboxyl groups of the resin with ammonia and mixing with water. The resulting dispersion or solution can generally be characterized by being stable without appreciable, if any, precipitation of the resin for a period of at least thirty (30) days and preferably for a period of at least 365 days or more at about 25~C.
Generally, for the purpose of this invention, about 100 to about 400 parts by weight water are used per 100 parts by weight neutralized resin, although more or less water can usually be used depending on whether a high or low viscosity dispersion or solution is desired or whether a high or low solids content is desired. It also depends on the type and amount of coalescing solvent (if any) and plasticizer used. The water-reduced coating composition, as an aqueous dispersion or solution, is applied as a coating onto a suitable substrate such as wood, masonry, various plastics and various metals. The water, ammonia and coalescing solvent are evaporated from the coating, usually at a temperature in the range of about 20~C to about 100~C, preferably about 25~C to about 50~C to leave a substantially water-insoluble coating of the coalesced resin and plasticizer. Generally, such a coating can be prepared and applied without the need for additional hardening agents or curatives to decrease the water sensitivity.
Therefore, it is an important feature of this invention that a durable crosslinked coating is formed on a substrate through the preparation of a particular resin having balanced hydrophilic and hydrophobic elements, preferably with a further balance of hard and soft segments, and the formation of a water-reduced composition of such resin with a combination of pigment and compatible plasticizer. The crosslinking occurs rapidly at ambient temperatures without the need for adding separate curatives or crosslinking agents. Improved adhesion to metal and glass substrates is also attained.
This invention is illustrated by the following examples which are merely for the purpose of illustration and are not to be regarded as limiting the scope of the invention or the manner in which it can be practiced. Unless specifically indicated otherwise, parts and percentages are given by weight.
Example 1 In this experiment, a latex was prepared in a three-liter reactor using the technique of this invention. The reactor utilized in this experiment was a Buchi reactor which was equipped with axial flow turbine-type agitation which was used throughout the polymerization. A buffer solution and two monomer solution were made for utilization in the q~ 9 3 polymerization. The buffer solution was made by mixing 1404 grams of water with 68 grams of a 39 percent aqueous solution of sodium alpha-olefin sulfonate surfactant, 2.4 grams of sodium acid pyrophosphate (electrolyte) and 3.6 grams of a-mmonium persulfate (initiator).
The sodium ~-olefin sulfonate soap used was of the structural formula:
OH
CH3-~CH2) 11-13 CH-CH2-SO3 Na~
The first monomer solution was prepared by mixing 780 grams of styrene, 1.2 grams of dodecylmercaptan, 348 grams of n-butyl acrylate, 24 grams of acrylic acid, and 12 grams of methacrylic acid.
After the reactor had been evacuated for 30 minutes, the buffer solution was charged into the reactor. Then 15 percent of the first monomer solution was charged into the reactor. The reactor was heated to a temperature of 135~F (57~C) and the polymerization was allowed to proceed for 45 minutes.
Then 36 grams of gamma-methacryloxypropyl-trimethoxysilane was added to the r~m~;n~er of themonomer solution to prepare a second monomer solution.
Then the second monomer solution was slowly added over a 3-hour period and the temperature was increased to 165~F (74~C). After all of the monomer solution was added, a solution containing 25 grams of a 28 percent aqueous solution of ammonia in 100 ml of water was added and the temperature was held at 165~F (74~C).
The pH of the latex was adjusted to 8.5 with the final latex having a solids content of about 41 percent.
The latex exhibited an excellent combination of properties for utilization in making self-crosslinking - 18 - ~ 7~ 3 coating formulations, such as paints, without including volatile organic compounds. In fact, coatings made with such coating formulations exhibited excellent solvent resistance because they are self-crosslinking. Such coating formulations areparticularly valuable for application to metals, wood and concrete.
A clear water-reducible coating formulation was made with the latex synthesized in this experiment.
This was done by mixing 0.6 phr (parts per 100 parts of resin) of ammonium hydroxide, 6 phr of Texanol~
ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate) and 4 phr of Kodaflex~ TXIB
plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) into the latex. Coatings made with this coating formulation proved to have excellent characteristics for coating substrates including outstanding solvent resistance. The coatings applied were also dry to the touch in only 5 to 7 minutes.
The clear coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes.
The coated concrete surface was also rubbed 100 times with a fabric cloth which was soaked with methyl ethyl ketone (MEK). The coating on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the coating had outstanding solvent resistance after being allowed to dry for only 4 hours.
Example 2 In this experiment, the latex synthesized in Example 1 was used in making a water-reducible self-- 19 - ~ 7~ ~
crosslinking grey paint. This was done by high speed mixing of 14.2 phr of water, 0.86 phr ammonium hydroxide, 8.6 phr of Texanol~ ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 5.7 phr of Kodaflex~ TXIB plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate), 1.4 phr of Dispersayd~ 181 dispersant, 22.9 phr of titanium dioxide, 22.9 phr of Nytal~ 300 flating agent (barium sulfate) and 1.4 phr of carbon black (No. 4) into the latex. In a subsequent let-down phase, 17.1 phr of water, 0.86 phr of hydroxyethyl cellulose and 0.29 phr of Drew L475 defoamer were added under conditions of high speed mixing.
- Coatings made with this grey paint formulation proved to have excellent characteristics for coating substrates including outstanding solvent resistance.
The coatings applied were also dry to the touch in only 5 to 7 minutes.
The grey coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes.
The painted concrete surface was also rubbed 100 times with a fabric cloth which was soaked with MEK. The grey paint on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the paint had outstanding solvent resistance after being allowed to dry for only 4 hours.
Example 3 In this experiment, the latex synthesized in Example 1 was used in making a water-reducible self-crosslinking white paint. This was done by high speed ~ 2 ~
mixing of 14.2 phr of water, 0.86 phr ammonium hydroxide, 8.6 phr of Texanol~ ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 5.7 phr of Kodaflex~ TXIB plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate), 1.4 phr of Dispersayd~ 181 dispersant, 22.9 phr of titanium dioxide and 22.9 phrof Nytal~ 300 flating agent (barium sulfate) into the latex. In a subsequent let-down phase, 17.1 phr of water, 0.86 phr of hydroxyethyl cellulose and 0.29 phr of Drew L475 defoamer were added under conditions of high-speed mixing.
Coatings made with this white paint proved to have excellent characteristics for coating substrates including outstanding solvent resistance. The coatings applied were also dry to the touch in only 5 to 7 minutes.
The white coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes.
The painted concrete surface was also rubbed 100 times with a fabric cloth which was soaked with MEK. The white paint on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the paint had outstanding solvent resistance after being allowed to dry for only 4 hours.
Example 4 In this experiment, the latex synthesized in Example 1 was used in making a water-reducible self-crosslinking black paint. This was done by high speed mixing of 14.2 phr of water, 0.86 phr ammonium hydroxide, 8.6 phr of Texanol~ ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 5.7 phr of Kodaflex~ TXIB plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate), 1.4 phr of Dispersayd~ 181 dispersant, 22.9 phr of silica, 22.9 phr of Nytal~ 300 flating agent (barium sulfate) and 1.4 phr of carbonblack (No. 4) into the latex. In a subsequent let-down phase, 17.1 phr of water, 0.86 phr of hydroxyethyl cellulose and 0.29 phr of Drew L475 defoamer were added under conditions of high speed mixing.
Coatings made with this black paint formulation proved to have excellent characteristics for coating substrates including outstanding solvent resistance.
- The coatings applied were also dry to the touch in only 5 to 7 minutes.
The black coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes. In fact, the painted concrete surface was rubbed 100 times with a fabric cloth which was soaked with MEK.
The black paint on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the paint had outstanding solvent resistance after being allowed to dry for only 4 hours.
The coating formulations made with the latices of this invention proved to offer excellent shear stability. The coating formulations also proved to have excellent in can stability. Latices which have a smaller particle size proved to crosslink more rapidly than those with larger particle sizes. It is accordingly preferred for such latices to have a particle size of about 90 to about 120 nanometers.
7 ~ ~
Comparative Example 5 In this experiment, a latex was prepared in a reactor using the emulsifier system described in United States Patent 4,968,741 and United States Patent 5,122,566. The reactor utilized in this experiment was equipped with baffles for agitation and was operated at about 200 rpm (revolutions per minute). A buffer solution, an initiator solution, and a monomer solution were made for utilization in the polymerization. The buffer solution was made by mixing 15.6 kilograms of water with 340 grams of the sodium salt of an alkyl phosphate ester having a pH of about 3 and 340 grams of dodecanol. The initiator solution was prepared by mixing 1.36 kilograms of water and 68 grams of ammonium persulfate. The monomer solution was prepared by mixing 8.85 kilograms of styrene, 27 grams of t-dodecyl mercaptan, 3.95 kilograms of n-butylacrylate, 272 grams of acrylic acid, 136 grams of methacrylic acid, and 408 grams of gamma-methacryloxypropyltrimethoxysilane.
After the reactor had been evacuated for 30 minutes, the buffer solution was charged into the reactor. Then 20~ of the monomer solution was charged into the reactor. The reactor was heated to a temperature of 165~F (74~C) and one-half of the initiator solution was added to the reactor. After about 30 minutes of polymerization the continuous addition of the remaining monomer solution was started. The additional monomer solution was added over a period of about three hours at a rate which was sufficient to maintain a temperature of about 165~F
(74~C) in the reactor. The r~m~'n~er of the initiator solution was charged into the reactor after about two hours of polymerization time.
7 ~ 3 The latex made utilizing this procedure had a solids content of 46.0, a pH of 1.88, a Brookfield viscosity of 583 centipoise, and had a coagulum level of 115 grams. The pH of the latex made was adjusted to 9.5 by the addition of ammonium hydroxide.
The latex made in this experiment was so unstable that it could not be formulated in to clear coating compositions or paints. This experiment accordingly shows the critical nature of utilizing an ~-olefin sulfonate soap in synthesizing the latex.
Variations in the present invention are possible in light of the description of it provided herein.
While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
Background of the Invention Most conventional coating resins are insoluble in water. Therefore, in general practice, they have been dissolved in a suitable organic solvent or dispersed in water with the aid of an emulsifying agent or surfactant in order to provide a coating composition suitable for application to a substrate surface. A
serious disadvantage of organic solvent solutions is that they are potentially toxic, flammable and environmental pollutants. Water-reducible coatings greatly reduce the magnitude of these problems. For this reason, water-based paints are currently being used as a replacement for oil-based paints in many applications.
Various water-reducible coating resins, such as the one described in U.S. Patent No. 4,474,926, have been developed. Water-reducible coatings which utilize such resins have been developed for a variety of purposes and have been widely accepted in many applications such as highway striping paint.
United States Patent 4,968,741 describes a coating for metal substrates which provides improved corrosion and rust resistance. Such coatings are of the water-reducible type and can be beneficially utilized in the automotive industry and other applications where good rust resistance is needed.
For instance, such coatings are excellent for coating bridges and other outdoor metal structures.
It is also critical for coatings made with water-reducible coating formulations to offer the desired combination of physical and chemical properties. For instance, in many applications, it is important for the coating to exhibit excellent flexibility, excellent ultra-violet light resistance and excellent solvent resistance. In applications which involve metal substrates, outstanding corrosion and rust-resistance is normally also sought.
For purposes of this patent application, an aqueous coating system is considered to be a colloidal dispersion of a resin in water which can be reduced by the addition of water and which forms a durable coating when applied to a substrate surface. The term aqueous coating system is used herein interchangeably with the term water-reducible coating. Other names which are sometimes applied to water-reducible coatings are water-born, water-solubilized and water-dilutable.
Summary of the Invention This invention relates to the synthesis of a latex which can be used in making self-crosslinking water-reducible coating compositions, such as paints, which offer excellent solvent resistance, reduced drying time and improved adhesion to metal and glass.
Coatings which are formulated with the latex of this invention are environmentally advantageous because they contain no or extremely low levels of volatile organic compounds and additionally offer excellent flexibility and excellent ultra-violet light resistance.
The present invention more specifically discloses a water-reducible coating composition which is comprised of (1) water; (2) a resin having repeat units which are derived from (a) about 30 to about 75 weight percent vinyl aromatic monomers, (b) about 20 to about 65 weight percent of alkyl acrylate monomers, (c) about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers, based on 100 weight percent monomers; (3) a wetting agent;
and (4) a defoamer.
The subject invention further reveals a process for producing a neutralized latex that is useful in the manufacture of self-crosslinkable water-reducible coatings which comprises: (1) free radical aqueous emulsion polymerizing at a pH of less than about 3.5, a monomer mixture which comprises, based on 100 weight percent monomers: (a) from about 30 to about 75 weight percent vinyl aromatic monomers, (b) from about 20 to about 65 weight percent of alkyl acrylate monomers, (c) from about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers; in the presence of about 0.2 to 3 phm of at least one ~-olefin sulfonate soap to produce a latex;
and (2) neutralizing the latex with ammonia to a pH
which is within the range of about 7 to about 10.5 to produce the neutralized latex.
The present invention also discloses a latex which is useful in the manufacture of self-crosslinkable water-reducible coatings, said latex being comprised of (1) water, (2) an emulsifier and (3) a polymer which is comprised of repeat units which are derived from (a) about 30 to about 75 weight percent vinyl aromatic monomers, (b) about 20 to about 65 weight percent of alkyl acrylate monomers, (c) about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers.
Detailed Description of the Invention The latices of this invention are prepared by free radical emulsion polymerization. The charge compositions used in the preparation of the latices of this invention contain monomers, at least one ~-olefin 0~97g3 sulfonate surfactant, and at least one free radical initiator. The monomer charge composition used in such polymerizations is comprised of ~a) from about 30 to about 75 weight percent vinyl aromatic monomers, (b) from about 20 to about 65 weight percent of alkyl acrylate monomers, (c) from about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers.
It is preferred for the polymer being synthesized to be comprised of from about 40 weight percent to about 70 weight percent vinyl aromatic monomers, from about 25 weight percent to about 55 weight percent alkyl acrylate monomers, from about 1.5 weight percent to about 5 weight percent alkyl propenoic acid monomers and from about 1 weight percent to about 3 weight percent acryloxyalkenyltrialkoxysilane monomers. It is more preferred for the polymer to be comprised of from about 63 weight percent to about 67 weight percent vinyl aromatic monomers, from about 27 weight percent to about 31 weight percent alkyl acrylate monomers, from about 2 weight percent to about 4 weight percent alkyl propenoic acid monomers and from about 1.5 weight percent to about 2 weight percent acryloxyalkenyltrialkoxysilane monomers.
Some representative examples of vinyl aromatic monomers which can be used include styrene, alpha-methyl styrene and vinyl toluene. Styrene and alpha-methyl styrene are the preferred vinyl aromatic monomers. Due to its relatively low cost, styrene is the most preferred vinyl aromatic monomer.
The alkyl acrylate monomers which can be employed have alkyl moieties which contain from 2 to about 10 carbon atoms. The alkyl acrylate monomer will preferably have an alkyl moiety which contains from 3 ~ 2~7~ 3 to 5 carbon atoms. Normal-butyl acrylate is a highly preferred alkyl acrylate monomer.
The alkyl propenoic acid monomers that can be used have the structural formula:
R
CH2=C-COOH
wherein R represents a hydrogen atom or an alkyl group cont~;n;ng from 1 to 4 carbon atoms. The R group can accordingly be represented by the formula -CnH
wherein n is an integer from 0 to 4. Some representative examples of alkyl propenoic acid monomers which can be used include: acrylic acid, methacrylic acid (2-methylpropenoic acid), 2-ethylpropenoic acid, 2-propylpropenoic acid and 2-butylpropenoic acid. The preferred alkyl propenoic acid monomers are acrylic acid and methacrylic acid.
In most cases, it is advantageous to use a combination of both acrylic acid and methacrylic acid as the unsaturated carbonyl compound component used in making the latex. For instance, the utilization of about 1 to about 3 weight percent acrylic acid with about 0.5 to about 1.5 weight percent methacrylic acid results in the latex having improved freeze-thaw stability. For example, the utilization of about 2 percent acrylic acid with 1 percent methacrylic acid as the unsaturated carbonyl compound component results in the latex produced being capable of withst~nA;ng more than five (5) freeze-thaw cycles. It is important for latices which are shipped through cold regions of the world to have this improved freeze-thaw stability.
The acryloxyalkenyltrialkoxysilane monomers which can be used are of the structural formula:
7 ~ ~
~C,H2 ~o - R2 Rl--C-C-o~CH2~Si-o-R3 O o R4 wherein Rl represents a hydrogen atom, a methyl group (-CH3) or an ethyl group (-CH2-CH3), wherein n represents an integer from O to 10 and wherein R2, R3 and R4 can be the same or different and are selected from alkyl groups which contains from 1 to 3 carbon atoms. It is preferred for R1 to be a hydrogen atom or a methyl group. It is most preferred from Rl to be a methyl group. It is preferred for n to represent an integer from 2 to 4 with it being most preferred for n to represent 3. It is preferred for R2, R3 and R4 to represent methyl groups or ethyl groups with methyl groups being most preferred. Gamma-methacryloxypropyltrimethoxysilane which has the structural formula:
~C~H2 ~O-CH3 CH3-C-C-O-~CH2 ~ Si-O-CH3 o O-CH3 is the most highly preferred acryloxyalkenyl-trialkoxysilane monomer.
The charge composition used in the preparation of the latices of this invention will contain a substantial quantity of water. The ratio between the total amount of monomers present in the charge composition and water can range between about 0.2:1 and about 1.2:1. It is generally preferred for the ratio of monomers to water in the charge composition to be within the range of about 0.8:1 and about 1.1:1.
For instance, it is very satisfactory to utilize a ratio of monomers to water in the charge composition of about 1:1.
i~2~9~ 3 The charge composition will also contain from about 0.2 phm (parts per hundred parts of monomer) to about 3 phm of at least one ~-olefin sulfonate soap.
It is normally preferred for the ~-olefin sulfonate surfactant to be present in the polymerization medium at a level within the range of about 0.4 phm to about 2 phm. It is generally more preferred for the charge composition to contain from about 0.5 phm to about 1 phm of the ~-olefin sulfonate soap.
The use of larger amounts of the ~-olefin sulfonate soap in the polymerization medium leads to better latex stability. However, the utilization of larger amounts of surfactant also leads to greater blushing in the ultimate coating and consequently less rust and corrosion resistance.
The free radical aqueous emulsion polymerizations used in preparing the latices of this invention are initiated with at least one free radical generator.
The free radical generator is normally employed at a concentration within the range of about 0.01 phm to about 1 phm. The free radical initiators which are commonly used include the various peroxygen compounds such as potassium persulfate, ammonium persulfate, benzoyl peroxide, hydrogen peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, decanoyl peroxide, lauryl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, t-butyl hydroperoxide, acetyl peroxide, methyl ethyl ketone peroxide, succinic acid peroxide, dicetyl peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroxymaleic acid, t-butyl peroxybenzoate, acetyl cyclohexyl sulfonyl peroxide and the like; the various azo compounds such as 2-t-butylazo-2-cyanopropane, dimethyl azodiisobutyrate, azodiisobutylronitrile, 2-t-butylazo-1-cyanocyclohexane, 1-t-amylazo-1-cyanocyclohexane and the like, the ~99~ 3 various alkyl perketals, such as 2,2-bis-(t-butyl-peroxy)butane and the like. Water-soluble peroxygen-free radical initiators are especially useful in such aqueous polymerizations.
The emulsion polymerizations of this invention are typically carried out at the temperature ranging between about 125~F (52~C) and 190~F (88~C). At temperatures above about 190~F (88~C), alkyl acrylate monomers, such as butyl acrylate, have a tendency to boil. Thus, a pressurized jacket would be required for heating such alkyl acrylate monomers to temperatures in excess of about 88~C. On the other hand, the polymerization reaction proceeds at a very slow rate at temperatures below about 125~F (52~C).
The slow rate of polymerization experienced at temperatures below about 125~F (52~C) results in the polymer having a nonuniform distribution of repeat units in its backbone. The slow rates of polymerization experienced at such low temperatures are also undesirable because they greatly reduce the throughput of the polymerization reactor.
It is generally preferred for the polymerization temperature to be maintained within the range of about 150~F (66~C) to 180~F (82~C). It is generally more preferred for the reaction temperature to be controlled within the range of about 160~F (71~C) to about 170 F (77 C). It is important for the polymerization to be conducted at a pH which is below about 3.5 so that a water-sensitive polymer is not produced. It is preferred for the pH of the polymerization medium to be maintained at a level of about 3.0 or less throughout the polymerization. As the polymerization proceeds, the pH of the polymerization medium will drop naturally. Thus, good results can be attained by ad~usting the pH of the initial monomer charge composition to within the range 7 ~ ~
g of about 3.0 to about 3.5 and allowing the polymerization to proceed. In such a case, the final pH of the polymerization medium will be about l.5 which is highly satisfactory.
In commercial operations, it is typically desirable to add about 15 percent to about 25 percent of the monomers in an initial charge. The initial charge is then allowed to react for a period of about 30 minutes to about 60 minutes. Then the balance of the monomers to be charged can be continuously charged into the reaction zone at a rate which is sufficient to maintain a reaction temperature within the desired temperature range. By continuously adding the monomers to the reaction medium while maint~;n1ng a relatively constant reaction temperature, very uniform polymers can be prepared.
In accordance with the process of this invention, the latex synthesized is then neutralized with ammonia to a pH within the range of about 7 to about lO.5. It is normally preferred for the latex to be neutralized to a pH within the range of 8 to lO and more preferred for the latex to be neutralized to a pH within the range of about 9.0 to about 9.5. This can be accomplished by simply dispersing ammonia throughout the latex to produce neutralized latex. The ammonia will normally be in the form of ammonium hydroxide.
The latex formed can be diluted with additional water to the concentration (solids content) that is desired. This latex can be used in the preparation of water-reducible coatings using techniques well-known to those skilled in the art. Generally, various pigments and plasticizers are added to the latex in the preparation of the water-reducible coating. Poor adhesion is a problem that is sometimes encountered with water-reducible resins. The adhesion of coatings made with water-reducible resins to substrates can be greatly improved by the addition of a plasticizer.
A film-forming, water-reducible composition, such as a paint, can be prepared by mixing the latex, one or more pigments and a plasticizer. It is not necessary to include a coalescing solvent in the film-forming, water-reducible formulation. For environmental reasons, it is preferred not to include a coalescing solvent in the formulation. However, a small amount (0 to about 50 grams per liter) of coalescing solvent can be included. In cases where a coalescing solvent is employed, it is preferable for it to be at least water-miscible and even more preferable for it to be water-soluble. Of the various coalescing solvents generally ester-alcohols, such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, are preferred.
It should be noted that the pigment, plasticizer and optionally the coalescing solvent can be mixed directly with the resin in its water emulsion or latex. In such an operation, the composite would automatically be in a water-reduced form when sufficient ammonia is used.
Paint formulations can be made utilizing the latices of this invention. Such paint formulations are comprised of one or more pigments and the latex (water, emulsifier system and resin). Such paints can optionally contain fillers, plasticizers, stabilizers, defoamers, dryers, fungicides, insecticides, antifouling agents and anticorrosive agents.
Pigments are normally added to paint formulations to impart color and hiding power to the coating.
Titanium dioxide is an example of a widely-used pigment which imparts hiding power and a white color.
Mineral pigments, such as oxides of iron and chromium, organic pigments, such as phthalocyanine, and active anticorrosive pigments, such as zinc phosphate, are representative examples of other widely-used pigments.
Fillers are normally inexpensive materials which are added to the paint formulation to attain the desired consistency and non-settling characteristics.
Fillers can also improve the physical properties of coatings, such as resistance to cracking and abrasion.
Some representative examples of widely utilized fillers include chalks, clays, micas, forms of barites and talcs, and silica.
Driers are chemical compounds, such as salts of cobalt, lead, manganese, barium and zinc, which speed up drying. Stabilizers are chemical agents which neutralize the destructive effects of heat and ultraviolet light. Fungicides and insecticides are commonly added to interior and exterior house paints.
Antifouling compounds are commonly added to marine paints to inhibit marine growth. Plasticizers are agents which control the hardness of the film or which impart flexibility.
Of the various plasticizers, it is desired that one be selected which is liquid at room temperature such as 25~C and have a sufficiently high boiling point, preferably at least 100~C, and even more preferably, at least 150~C, so that they do not volatilize from the coating composition when applied to a substrate. Plasticizers which contain multiple hydroxyl groups should be avoided because their use can lead to instability. The plasticizer should enhance the water insolubility of a dried coating of the coalesced resin. Further, the plasticizer, or mixture of plasticizers, must be characterized by being compatible with the resin itself. For this characterization, a solubility parameter in the range of about 8 to about 16 is required. Such solubility parameter is of the type described in The Encyclopedia - 12 - ~ 7 ~ ~
of Polymer Science and Technology, Volume 3, Page 854, 1965, John Wiley and Sons, Inc., which is simply determined by the equation 6 = ( ~ ~ ) /v = F/MW/d where ~ = solubility parameter F = sum of the pertinent molar attraction constants of groups determined by Small, P A [(J Appl Chem 3, 71, (1953)]
V = Molar volume at 25~C
MW = molecular weight d = density at 25~C
Various plasticizers can be used for this purpose. They can, for example, be of the type listed in the Federation Series on Coatings Technology, Unit Twenty-two, entitled "Plasticizers," published April 1974, so long as they fulfill the melting point, boiling point and compatibility requirements. Some representative examples of preferred plasticizers include: butyl benzyl phthalate, blends of diethyleneglycol dibenzoate and dipropylene glycol dibenzoate, and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate.
Representative of various plasticizers are cyclic plasticizers such as phosphoric acid esters, phthalic anhydride esters and trimellitic acid esters as well as N-cyclohexyl-p-toluene sulfonamide, dibenzyl sebacate, diethylene glycol dibenzoate, di-t-octylphenylether, dipropane diol dibenzoate, N-ethyl-p-toluene sulfonamide, isopropylidenediphenoxypropanol, alkylated naphthalene, polyethylene glycol dibenzoate, o-p-toluene sulfonamide, trimethylpentanediol dibenzoate and trimethylpentanediol monoisobutyrate monobenzoate.
Representative of various acyclic plasticizers are adipic acid esters, azelaic acid esters, citric acid esters, acetylcitric acid esters, myristic acid esters, phosphoric acid esters, ricinoleic acid esters, acetylricinoleic acid esters, sebacic acid esters, stearic acid esters, epoxidized esters, as well as 1,4-butane diol dicaprylate, butoxyethyl pelargonate di[(butoxyethoxy)ethoxy] methane, dibutyl tartrate, diethylene glycol dipelargonate, diisooctyl diglycolate, isodecyl nonanoate, tetraethylene glycol di(2-ethylbutyrate), triethylene glycol di(2-ethyl-hexanoate), triethylene glycol dipelargonate and 2,2,4-trimethyl-1,3-pentane diol diisobutyrate.
Additional various plasticizers, cyclic, acyclic, and otherwise, include chlorinated paraffins, hydrogenated terphenyls, substituted phenols, propylene glycols, polypropylene glycol esters, polyethylene glycol esters, melamines, epoxidized soys, oils, melamines, liquid, hydrogenated abietate esters, epoxytallate esters, alkyl phthalyl alkyl glycolates, sulfonamides, sebacate esters, aromatic epoxies, aliphatic epoxies, liquid poly(~-methyl styrene), maleate esters, mellitate esters, benzoates, benzyl esters, tartrates, succinates, isophthalates, orthophthalates, butyrates, fumarates, glutarates, dicaprylates, dibenzoates and dibenzyl esters. It is to be appreciated that relatively low molecular weight polymers and copolymers derived from monoolefins containing 4 to 6 carbon atoms, mixtures of diolefins and monoolefins containing 4 to 6 carbon atoms as well as such hydrocarbons and hydrocarbon mixtures with styrene and/or ~-methyl styrene can also be used.
The preferred esters are prepared from the reaction of carboxylic and dicarboxylic acids including fatty acids, such as the phthalic acids, benzoic acid, dibenzoic acid, adipic acid, sebacic acid, stearic acid, maleic acid, tartaric acid, succinic acid, butyric acid, fumaric acid and glutaric acid with hydrocarbon diols, preferably saturated hydrocarbon diols, having about 7 to 13 carbon atoms.
Representative of various phosphoric acid esters are cresyl diphenyl phosphate, tricresyl phosphate, dibutyl phenyl phosphate, diphenyl octyl phosphate, methyl diphenyl phosphate, tributyl phosphate, triphenyl phosphate, tri(2-butoxyethyl) phosphate, tri(2-chloroethyl) phosphate, tri-2(chloropropyl) phosphate and trioctyl phosphate.
Representative of various phthalic anhydride esters are butyl octyl phthalate, butyl 2-ethylhexyl phthalate, butyl n-octyl phthalate, dibutyl phthalate, diethyl phthalate, diisodecyl phthalate, dimethyl phthalate dioctyl phthalates, di(2-ethylhexyl) phthalate, diisooctyl phthalate, di-tridecyl phthalate, n-hexyl n-decyl phthalate, n-octyl n-decyl phthalate, alkyl benzyl phthalate, bis(4-methyl-1,2-pentyl) phthalate, butyl benzyl phthalate, butyl cyclohexyl phthalate, di(2-butoxyethyl) phthalate, dicyclohexyl isodecyl phthalate, dicyclohexyl phthalate, diethyl isophthalate, di n-heptyl phthalate, dihexyl phthalate, diisononyl phthalate, di(2-methoxyethyl) phthalate, dimethyl isophthalate, dinonyl phthalate, dioctyl phthalates, dicapryl phthalate, di(2-ethylhexyl) isophthalate, mixed dioctyl phthalates, diphenyl phthalate, 2-(ethylhexyl) isobutyl phthalate, butyl phthalyl butyl glycolate, ethyl (and methyl) phthalyl ethyl glycolate, polypropylene glycol bis(amyl) phthalate, hexyl isodecyl phthalate, isodecyl tridecyl phthalate and isooctyl isodecyl phthalate.
Representative of trimellitic acid esters are triisooctyl trimellitate, tri-n-octyl n-decyl trimellitate, trioctyl trimellitate, tri(2-ethylhexyl) 7 ~ ~
trimellitate, tri-n-hexyl n-decyl trimellitate, tri-n-hexyl trimellitate, triisodecyl trimellitate and triisononyl trimellitate.
Representative of various adipic acid esters are di[2-(2-butoxyethoxy) ethyl] adipate, di(2-ethylhexyl) adipate, diisodecyl adipate, dioctyl adipates (including diisooctyl adipate) n-hexyl n-decyl adipate, n-octyl n-decyl adipate and di-n-heptyl adipate.
Representative examples of sebacic acid esters are dibutyl sebacate, di(2-ethylhexyl) sebacate, dibutoxyethyl sebacate, diisooctyl sebacate and diisopropyl sebacate.
Representative examples of azelaic acid esters are di(2-ethylhexyl) acelate dicyclohexyl acelate, diisobutyl azelate and diisooctyl azelate. In the practice of this invention, the water-reducible composition of resin, plasticizer and coalescing solvent, if used, is water-reduced by neutralizing the carboxyl groups of the resin with ammonia and mixing with water. The resulting dispersion or solution can generally be characterized by being stable without appreciable, if any, precipitation of the resin for a period of at least thirty (30) days and preferably for a period of at least 365 days or more at about 25~C.
Generally, for the purpose of this invention, about 100 to about 400 parts by weight water are used per 100 parts by weight neutralized resin, although more or less water can usually be used depending on whether a high or low viscosity dispersion or solution is desired or whether a high or low solids content is desired. It also depends on the type and amount of coalescing solvent (if any) and plasticizer used. The water-reduced coating composition, as an aqueous dispersion or solution, is applied as a coating onto a suitable substrate such as wood, masonry, various plastics and various metals. The water, ammonia and coalescing solvent are evaporated from the coating, usually at a temperature in the range of about 20~C to about 100~C, preferably about 25~C to about 50~C to leave a substantially water-insoluble coating of the coalesced resin and plasticizer. Generally, such a coating can be prepared and applied without the need for additional hardening agents or curatives to decrease the water sensitivity.
Therefore, it is an important feature of this invention that a durable crosslinked coating is formed on a substrate through the preparation of a particular resin having balanced hydrophilic and hydrophobic elements, preferably with a further balance of hard and soft segments, and the formation of a water-reduced composition of such resin with a combination of pigment and compatible plasticizer. The crosslinking occurs rapidly at ambient temperatures without the need for adding separate curatives or crosslinking agents. Improved adhesion to metal and glass substrates is also attained.
This invention is illustrated by the following examples which are merely for the purpose of illustration and are not to be regarded as limiting the scope of the invention or the manner in which it can be practiced. Unless specifically indicated otherwise, parts and percentages are given by weight.
Example 1 In this experiment, a latex was prepared in a three-liter reactor using the technique of this invention. The reactor utilized in this experiment was a Buchi reactor which was equipped with axial flow turbine-type agitation which was used throughout the polymerization. A buffer solution and two monomer solution were made for utilization in the q~ 9 3 polymerization. The buffer solution was made by mixing 1404 grams of water with 68 grams of a 39 percent aqueous solution of sodium alpha-olefin sulfonate surfactant, 2.4 grams of sodium acid pyrophosphate (electrolyte) and 3.6 grams of a-mmonium persulfate (initiator).
The sodium ~-olefin sulfonate soap used was of the structural formula:
OH
CH3-~CH2) 11-13 CH-CH2-SO3 Na~
The first monomer solution was prepared by mixing 780 grams of styrene, 1.2 grams of dodecylmercaptan, 348 grams of n-butyl acrylate, 24 grams of acrylic acid, and 12 grams of methacrylic acid.
After the reactor had been evacuated for 30 minutes, the buffer solution was charged into the reactor. Then 15 percent of the first monomer solution was charged into the reactor. The reactor was heated to a temperature of 135~F (57~C) and the polymerization was allowed to proceed for 45 minutes.
Then 36 grams of gamma-methacryloxypropyl-trimethoxysilane was added to the r~m~;n~er of themonomer solution to prepare a second monomer solution.
Then the second monomer solution was slowly added over a 3-hour period and the temperature was increased to 165~F (74~C). After all of the monomer solution was added, a solution containing 25 grams of a 28 percent aqueous solution of ammonia in 100 ml of water was added and the temperature was held at 165~F (74~C).
The pH of the latex was adjusted to 8.5 with the final latex having a solids content of about 41 percent.
The latex exhibited an excellent combination of properties for utilization in making self-crosslinking - 18 - ~ 7~ 3 coating formulations, such as paints, without including volatile organic compounds. In fact, coatings made with such coating formulations exhibited excellent solvent resistance because they are self-crosslinking. Such coating formulations areparticularly valuable for application to metals, wood and concrete.
A clear water-reducible coating formulation was made with the latex synthesized in this experiment.
This was done by mixing 0.6 phr (parts per 100 parts of resin) of ammonium hydroxide, 6 phr of Texanol~
ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate) and 4 phr of Kodaflex~ TXIB
plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) into the latex. Coatings made with this coating formulation proved to have excellent characteristics for coating substrates including outstanding solvent resistance. The coatings applied were also dry to the touch in only 5 to 7 minutes.
The clear coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes.
The coated concrete surface was also rubbed 100 times with a fabric cloth which was soaked with methyl ethyl ketone (MEK). The coating on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the coating had outstanding solvent resistance after being allowed to dry for only 4 hours.
Example 2 In this experiment, the latex synthesized in Example 1 was used in making a water-reducible self-- 19 - ~ 7~ ~
crosslinking grey paint. This was done by high speed mixing of 14.2 phr of water, 0.86 phr ammonium hydroxide, 8.6 phr of Texanol~ ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 5.7 phr of Kodaflex~ TXIB plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate), 1.4 phr of Dispersayd~ 181 dispersant, 22.9 phr of titanium dioxide, 22.9 phr of Nytal~ 300 flating agent (barium sulfate) and 1.4 phr of carbon black (No. 4) into the latex. In a subsequent let-down phase, 17.1 phr of water, 0.86 phr of hydroxyethyl cellulose and 0.29 phr of Drew L475 defoamer were added under conditions of high speed mixing.
- Coatings made with this grey paint formulation proved to have excellent characteristics for coating substrates including outstanding solvent resistance.
The coatings applied were also dry to the touch in only 5 to 7 minutes.
The grey coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes.
The painted concrete surface was also rubbed 100 times with a fabric cloth which was soaked with MEK. The grey paint on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the paint had outstanding solvent resistance after being allowed to dry for only 4 hours.
Example 3 In this experiment, the latex synthesized in Example 1 was used in making a water-reducible self-crosslinking white paint. This was done by high speed ~ 2 ~
mixing of 14.2 phr of water, 0.86 phr ammonium hydroxide, 8.6 phr of Texanol~ ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 5.7 phr of Kodaflex~ TXIB plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate), 1.4 phr of Dispersayd~ 181 dispersant, 22.9 phr of titanium dioxide and 22.9 phrof Nytal~ 300 flating agent (barium sulfate) into the latex. In a subsequent let-down phase, 17.1 phr of water, 0.86 phr of hydroxyethyl cellulose and 0.29 phr of Drew L475 defoamer were added under conditions of high-speed mixing.
Coatings made with this white paint proved to have excellent characteristics for coating substrates including outstanding solvent resistance. The coatings applied were also dry to the touch in only 5 to 7 minutes.
The white coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes.
The painted concrete surface was also rubbed 100 times with a fabric cloth which was soaked with MEK. The white paint on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the paint had outstanding solvent resistance after being allowed to dry for only 4 hours.
Example 4 In this experiment, the latex synthesized in Example 1 was used in making a water-reducible self-crosslinking black paint. This was done by high speed mixing of 14.2 phr of water, 0.86 phr ammonium hydroxide, 8.6 phr of Texanol~ ester-alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 5.7 phr of Kodaflex~ TXIB plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate), 1.4 phr of Dispersayd~ 181 dispersant, 22.9 phr of silica, 22.9 phr of Nytal~ 300 flating agent (barium sulfate) and 1.4 phr of carbonblack (No. 4) into the latex. In a subsequent let-down phase, 17.1 phr of water, 0.86 phr of hydroxyethyl cellulose and 0.29 phr of Drew L475 defoamer were added under conditions of high speed mixing.
Coatings made with this black paint formulation proved to have excellent characteristics for coating substrates including outstanding solvent resistance.
- The coatings applied were also dry to the touch in only 5 to 7 minutes.
The black coating formulation made was applied to a concrete block which was allowed to dry for a period of 4 hours at room temperature. The coating did not dissolve in Skydrol~ phosphated esters which was applied to the surface for a period of 10 minutes. In fact, the painted concrete surface was rubbed 100 times with a fabric cloth which was soaked with MEK.
The black paint on the concrete block remained intact after being rubbed with the MEK-soaked cloth. The severe test shows that the paint had outstanding solvent resistance after being allowed to dry for only 4 hours.
The coating formulations made with the latices of this invention proved to offer excellent shear stability. The coating formulations also proved to have excellent in can stability. Latices which have a smaller particle size proved to crosslink more rapidly than those with larger particle sizes. It is accordingly preferred for such latices to have a particle size of about 90 to about 120 nanometers.
7 ~ ~
Comparative Example 5 In this experiment, a latex was prepared in a reactor using the emulsifier system described in United States Patent 4,968,741 and United States Patent 5,122,566. The reactor utilized in this experiment was equipped with baffles for agitation and was operated at about 200 rpm (revolutions per minute). A buffer solution, an initiator solution, and a monomer solution were made for utilization in the polymerization. The buffer solution was made by mixing 15.6 kilograms of water with 340 grams of the sodium salt of an alkyl phosphate ester having a pH of about 3 and 340 grams of dodecanol. The initiator solution was prepared by mixing 1.36 kilograms of water and 68 grams of ammonium persulfate. The monomer solution was prepared by mixing 8.85 kilograms of styrene, 27 grams of t-dodecyl mercaptan, 3.95 kilograms of n-butylacrylate, 272 grams of acrylic acid, 136 grams of methacrylic acid, and 408 grams of gamma-methacryloxypropyltrimethoxysilane.
After the reactor had been evacuated for 30 minutes, the buffer solution was charged into the reactor. Then 20~ of the monomer solution was charged into the reactor. The reactor was heated to a temperature of 165~F (74~C) and one-half of the initiator solution was added to the reactor. After about 30 minutes of polymerization the continuous addition of the remaining monomer solution was started. The additional monomer solution was added over a period of about three hours at a rate which was sufficient to maintain a temperature of about 165~F
(74~C) in the reactor. The r~m~'n~er of the initiator solution was charged into the reactor after about two hours of polymerization time.
7 ~ 3 The latex made utilizing this procedure had a solids content of 46.0, a pH of 1.88, a Brookfield viscosity of 583 centipoise, and had a coagulum level of 115 grams. The pH of the latex made was adjusted to 9.5 by the addition of ammonium hydroxide.
The latex made in this experiment was so unstable that it could not be formulated in to clear coating compositions or paints. This experiment accordingly shows the critical nature of utilizing an ~-olefin sulfonate soap in synthesizing the latex.
Variations in the present invention are possible in light of the description of it provided herein.
While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
Claims (20)
1. A water-reducible coating composition which is comprised of (1) water; (2) a resin having repeat units which are derived from (a) about 30 to about 75 weight percent vinyl aromatic monomers, (b) about 20 to about 65 weight percent of alkyl acrylate monomers, (c) about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers, based on 100 weight percent monomers; (3) a wetting agent;
and (4) a defoamer.
and (4) a defoamer.
2. A process for producing a neutralized latex that is useful in the manufacture of self-crosslinkable water-reducible coatings which comprises: (1) free radical aqueous emulsion polymerizing at a pH of less than about 3.5 a monomer mixture which comprises, based on 100 weight percent monomers: (a) from about 30 to about 75 weight percent vinyl aromatic monomers, (b) from about 20 to about 65 weight percent of alkyl acrylate monomers, (c) from about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers; in the presence of about 0.2 to 3 phm of at least one .alpha.-olefin sulfonate soap to produce a latex; and (2) neutralizing the latex with ammonia to a pH which is within the range of about 7 to about 10.5 to produce the neutralized latex.
3. A latex which is useful in the manufacture of self-crosslinkable water-reducible coatings, said latex being comprised of (1) water, (2) an emulsifier and (3) a polymer which is comprised of repeat units which are derived from (a) about 30 to about 75 weight percent vinyl aromatic monomers, (b) about 20 to about 65 weight percent of alkyl acrylate monomers, (c) from about 1 to about 8 weight percent alkyl propenoic acid monomers and (d) about 0.5 to about 5 weight percent acryloxyalkenyltrialkoxysilane monomers.
4. A water-reducible coating composition as specified in claim 1 wherein the acryloxyalkenyltrialkoxysilane monomer is of the structural formula:
wherein R1 is selected from the group consisting of hydrogen atoms, methyl groups, and ethyl groups, wherein n represents an integer from 0 to 10, and wherein R2, R3 and R4 can be the same or different and are selected from alkyl groups which contains from 1 to 3 carbon atoms.
wherein R1 is selected from the group consisting of hydrogen atoms, methyl groups, and ethyl groups, wherein n represents an integer from 0 to 10, and wherein R2, R3 and R4 can be the same or different and are selected from alkyl groups which contains from 1 to 3 carbon atoms.
5. A water-reducible coating composition as specified in claim 4 wherein R1 is selected from the group consisting of hydrogen atoms and methyl groups;
wherein n represents an integer from 2 to 4; and wherein R2, R3 and R4 are selected from methyl groups and ethyl groups.
wherein n represents an integer from 2 to 4; and wherein R2, R3 and R4 are selected from methyl groups and ethyl groups.
6. A water-reducible coating composition as specified in claim 5 wherein the vinyl aromatic monomer is styrene.
7. A water-reducible coating composition as specified in claim 6 wherein the alkyl acrylate monomer is butyl acrylate.
8. A water-reducible coating composition as specified in claim 7 wherein the alkyl propenoic acid monomer is selected from the group consisting of acrylic acid and methacrylic acid.
9. A water-reducible coating composition as specified in claim 7 wherein the alkyl propenoic acid monomer is a mixture of acrylic acid and methacrylic acid.
10. A water-reducible coating composition as specified in claim 9 wherein the repeat units of said resin are derived from about 40 weight percent to about 70 weight percent styrene, from about 25 weight percent to about 55 weight percent butyl acrylate, from about 1.5 weight percent to about 5 weight percent acrylic acid and methacrylic acid monomers, and from about 1 weight percent to about 3 weight percent of the acryloxyalkenyltrialkoxysilane monomer.
11. A water-reducible coating composition as specified in claim 10 wherein the acryloxyalkenyltrialkoxysilane monomer is gamma-methacryloxypropyltrimethoxysilane.
12. A water-reducible coating composition as specified in claim 11 wherein the repeat units of said resin are derived from about 63 weight percent to about 67 weight percent styrene, from about 27 weight percent to about 31 weight percent butyl acrylate, from about 2 weight percent to about 4 weight percent acrylic acid and methacrylic acid monomers, and from about 1.5 weight percent to about 2 weight percent gamma-methacryloxypropyltrimethoxysilane monomer.
13. A water-reducible coating composition as specified in claim 12 wherein the repeat units in said resin are derived from about 1 weight percent to about 3 weight percent acrylic acid and about 0.5 weight percent to about 1.5 weight percent methacrylic acid.
14. A water-reducible coating composition as specified in claim 13 which is further comprised of at least one pigment.
15. A water-reducible coating composition as specified in claim 14 which is further comprised of at least one filler.
16. A water-reducible coating composition as specified in claim 15 which is further comprised of a plasticizer.
17. A water-reducible coating composition as specified in claim 16 wherein said plasticizer has a boiling point of at least 100°C.
18. A latex as specified in claim 3 wherein the .alpha.-oelfin sulfonate soap is present in an amount which is within the range of about 0.4 phr to about 2 phr.
19. A latex as specified in claim 3 wherein the .alpha.-oelfin sulfonate soap is present in an amount which is within the range of about 0.5 phr to about 1 phr.
20. A process as specified in claim 2 wherein said polymerization is conducted at a temperature which is within the range of about 150°F to about 180°F.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77424296A | 1996-12-27 | 1996-12-27 | |
| US08/774,242 | 1996-12-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2199793A1 true CA2199793A1 (en) | 1998-06-27 |
Family
ID=25100657
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002199793A Abandoned CA2199793A1 (en) | 1996-12-27 | 1997-03-12 | Self-crosslinking coating formulation |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPH10195368A (en) |
| KR (1) | KR19980063275A (en) |
| BR (1) | BR9701333A (en) |
| CA (1) | CA2199793A1 (en) |
| ID (1) | ID19294A (en) |
| PL (1) | PL319191A1 (en) |
| ZA (1) | ZA972246B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9404006B2 (en) | 2013-03-15 | 2016-08-02 | Akzo Nobel Coatings International B.V. | Hybrid water dispersions, (poly)ethylene (meth)acrylic acid copolymer composite latex emulsions, hybrid (poly)ethylene (meth)acrylic acid organosilane composite latex emulsions, and coating compositions formed therefrom |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5325377B2 (en) * | 2005-08-08 | 2013-10-23 | エスケー化研株式会社 | Water-based paint composition |
| US20110017611A1 (en) * | 2007-12-21 | 2011-01-27 | Basf Se | Oxygen-scavenging mixtures |
| KR101127529B1 (en) * | 2011-09-28 | 2012-03-22 | 대보하우징 주식회사 | Composition for coating road pavement with quick drying characteristic |
| CN103834240A (en) * | 2014-03-19 | 2014-06-04 | 王勇 | TPE (Thermoplastic Polyolefin) rubber waterproof coating film and preparation method thereof |
-
1997
- 1997-03-12 CA CA002199793A patent/CA2199793A1/en not_active Abandoned
- 1997-03-14 ZA ZA9702246A patent/ZA972246B/en unknown
- 1997-03-17 JP JP9062952A patent/JPH10195368A/en active Pending
- 1997-03-18 BR BR9701333A patent/BR9701333A/en not_active Application Discontinuation
- 1997-03-26 KR KR1019970010500A patent/KR19980063275A/en not_active Application Discontinuation
- 1997-03-27 PL PL97319191A patent/PL319191A1/en unknown
- 1997-03-27 ID IDP971030A patent/ID19294A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9404006B2 (en) | 2013-03-15 | 2016-08-02 | Akzo Nobel Coatings International B.V. | Hybrid water dispersions, (poly)ethylene (meth)acrylic acid copolymer composite latex emulsions, hybrid (poly)ethylene (meth)acrylic acid organosilane composite latex emulsions, and coating compositions formed therefrom |
Also Published As
| Publication number | Publication date |
|---|---|
| ID19294A (en) | 1998-07-02 |
| ZA972246B (en) | 1997-09-17 |
| KR19980063275A (en) | 1998-10-07 |
| PL319191A1 (en) | 1998-07-06 |
| BR9701333A (en) | 1998-11-10 |
| MX9701940A (en) | 1998-06-28 |
| JPH10195368A (en) | 1998-07-28 |
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