Non-ionic resins and their use in antifouling building compositions

Abstract

Disclosed herein are stable nonionic resin compositions compatible with cationic resin compositions, and blends of nonionic resins and cationic resins. Primer and topcoat compositions containing such blends are capable of preventing migration of stains to the top of the paint film.

Description

Field of the Invention

[0001] The present invention relates to nonionic resins and their use in low VOC, waterborne, antifouling building compositions, including but not limited to primer or topcoat compositions containing cationic resins or cationic additives. Background of the Invention

[0003] Certain substrates to be painted, such as wood, contain tannins, which are astringent polyphenolic biomolecules that can penetrate paint films (including primer layers) and stain topcoat layers, becoming undesirable visible stains on the painted substrate. Other stains include crayons, lipstick, markers, coffee, wine, etc. and other stains on walls, and water drop stains on ceilings, which can penetrate paint films.

[0004] Conventional solvent-based alkyd coatings block stains but have odor and high volatile organic component (VOC) emissions. Hydrophobic waterborne acrylic resins have been used to block stains by forming a hydrophobic paint film layer. In these hydrophobic waterborne systems, stains still penetrate into the primer layer and eventually the topcoat.

[0005] Most stains are anionic in nature and can be prevented from migrating by cationic resins in waterborne building compositions. Cationic resins restrict the migration of water-soluble stains in waterborne coating applications. Cationic resins form complexes with anionic stains in an ion exchange setting, rendering the stains insoluble and trapped or locked in the primer film as it dries. However, cationic resins are generally highly hydrophilic and can increase the water sensitivity of the building composition and paint film. Increased water sensitivity in cationic coatings can result in loss of wet adhesion, scrub resistance, and blister resistance.

[0006] As discussed in U.S. Pat. No. 5,312,863, conventional water-based latex coatings are typically anionic. Anionic latex polymer binders are typically prepared by aqueous emulsion polymerization techniques using nonionic and / or anionic surfactants. These anionic latex polymer binders are blended with opacifying pigments, extender pigments, and dispersed with anionic pigment dispersants to form water-based latex coatings or paints. The anionic binders typically contain anionic functional groups such as carboxylate groups. Functionalization of these anionic latex polymers with amines, acetoacetates, or amides (such as ethylene urea derivatives) can improve wet adhesion to substrates. The '863 patent and the references cited therein are incorporated by reference in their entirety.

[0007] However, heretofore, cationic resins have not been blended or mixed with anionic resins to alleviate the water sensitivity problems associated with cationic resins. Blending or mixing cationic resins with anionic resins tends to result in coarse particle formation or gelation and generally results in a loss of performance and physical properties.

[0008] Therefore, there remains a need for aqueous formulations that have improved stain resistance and can prevent stain migration from the substrate to the topcoat while minimizing the water sensitivity of the paint film. More specifically, such anti-stain formulations utilize the stain-locking ability of cationic resins while mitigating their incompatibility when blended with nonionic resins to mitigate or prevent the formation of coarse particles or gels. Summary of the invention

[0009] Thus, the present invention relates to novel waterborne building compositions that pair cationic resins that lock in stains with novel nonionic resins that minimize or improve the water sensitivity of the cationic resins. The nonionic resins of the present invention are stable and compatible with the cationic resins, i.e., the nonionic resins of the present invention do not form grit or gels when blended with the cationic resins.

[0010] In one embodiment of the present invention, the cationic resin provides stain blocking capability and the nonionic resin enhances film formation and adhesion to substrates. Preferably, the nonionic resin of the present invention is free or substantially free of acid monomers, such as monomers with carboxylic acids, and free or substantially free of all monomers with anionic groups, such as monomers with phosphates, sulfonates, and other anionically charged monomers. Substantially free of acid monomers as used herein refers to a low level of less than 0.25 wt. %, preferably less than 0.125 wt. % of the total monomer content. Preferably, the nonionic resin of the present invention is free of acid monomers.

[0011] Without being bound by any particular theory, the inventors of the present invention have found that polymerization, preferably emulsion polymerization, can be carried out in the absence of acid monomers when the nonionic surfactant used for seeding or forming micelles has a high hydrophilic-lipophilic balance (HLB) value of about 14 to about 18, preferably about 14 to about 17, preferably about 15 to about 18. The nonionic surfactant may range from about 1 wt % to 8 wt %, preferably from about 5 wt % to 7 wt %, preferably from about 5.5 wt % to 6.5 wt %. In a preferred embodiment, except as discussed below, the only surfactant used in the polymerization is a nonionic surfactant.

[0012] The nonionic surfactant has a high HLB value. Without being bound by any particular theory, a higher hydrophilicity is required to stabilize the latex particles because the nonionic nature of these latexes results in no static stability.

[0013] In certain embodiments, a small amount of anionic surfactant can be used instead of nonionic surfactant in the inoculation stage at the beginning of polymerization to better control the particle size of seed formation. The total amount of anionic surfactant can be from 0 wt % to about 0.25 wt %, preferably from 0.01 wt % to about 0.25 wt %, preferably from about 0.035 wt % to about 0.15 wt %, preferably from about 0.05 wt % to about 0.15 wt %, based on the total monomer content. Without being limited to any particular theory, the inventors of the present invention believe that anionic surfactants are more effective in controlling particle size, and low levels of anionic surfactants are compatible with latex and cationic paints.

[0014] In another embodiment, optional polymerizable hydrophilic components (such as polymerizable ethylene oxide or propylene oxide) are copolymerized to form nonionic resins of the present invention. The hydrophilic part on the nonionic resin provides additional attraction for water in aqueous resin compositions or building compositions to alleviate or reduce condensation. The polymerizable hydrophilic components are present in an amount of 0 wt % to about 10 wt %, 0 wt % to about 5 wt %, or about 1.0 wt % to about 4.0 wt %, or about 1.5 wt % to about 3.5 wt %. In a preferred embodiment, polymerizable hydrophilic components are omitted, i.e., present in an amount of 0 wt %.

[0015] It should be noted that when a polymerizable hydrophilic component is included in the monomer mixture to be copolymerized, the amount of nonionic surfactant required for polymerization can be reduced to the lower portion of the 1 wt % to 8 wt % discussed above. In such a case, the range of the nonionic surfactant is from about 1 wt % to about 3.5 wt %, or from about 1 wt % to about 3.0 wt %.

[0016] The percentages of the components of the nonionic resins described herein are given as weight percent of active ingredients, including the weight of solid monomers and active ingredients of additives, excluding water.

[0017] In another embodiment, the aqueous paint composition comprising the blend of the nonionic resin and the cationic resin of the present invention further comprises a rust inhibitor to minimize or prevent rusting in metal paint cans. For primer compositions that can be applied to substrates including metal substrates, flash rust inhibitors are preferred. In addition, organic flash rust inhibitors are preferred due to their efficiency and compatibility.

[0018] One embodiment of the present invention relates to a substantially nonionic latex resin composition polymerized from:

[0019] A monomer mixture comprising at least one nonionic (meth)acrylate monomer, wherein the monomer mixture is substantially free of acid monomers or other monomers with anionic groups, and

[0020] Nonionic surfactants, ranging from about 4 wt% to 8 wt%, preferably from about 5 wt% to 7 wt%, preferably from about 5.5 wt% to 6.5 wt%,

[0021] wherein the nonionic surfactant has a hydrophile-lipophile balance (HLB) value of about 14 to about 18, preferably about 14 to about 17, preferably about 15 to about 18,

[0022] The weight percentages stated do not include water.

[0023] The substantially nonionic latex resin composition may additionally be polymerized with an inoculum amount of anionic surfactant ranging from 0 wt % to about 0.25 wt %, preferably 0.01 wt % to about 0.25 wt %, preferably about 0.05 wt % to about 0.15 wt %, based on the total monomer content.

[0024] The monomer mixture does not contain acid monomers or other monomers with anionic groups, or the acid monomers or other monomers with anionic groups are less than 0.25 wt %, preferably less than 0.125 wt % of the total monomer content.

[0025] The monomer mixture may further comprise a polymerizable nonionic hydrophilic component, wherein the polymerizable nonionic hydrophilic component is preferably present at 0 wt % to about 10 wt %, 0 wt % to about 5 wt %, about 1.0 wt % to about 4.0 wt %, or about 1.5 wt % to about 3.5 wt %.

[0026] The polymerizable hydrophilic component comprises a polymerizable polyethylene glycol monomer or a polymerizable polypropylene glycol monomer. The polymerizable polyethylene glycol monomer is preferably a methoxy polyethylene glycol methacrylate monomer.

[0027] In one embodiment, only nonionic surfactants are used in the polymerization to form micelles and the substantially nonionic latex resin.

[0028] Another embodiment of the present invention is directed to a paint composition, preferably a primer or topcoat composition, comprising a blend of the substantially nonionic latex resin composition of claim 1 and a cationic resin.

[0029] The paint composition may further include a rust inhibitor.

[0030] The range of the blend of the nonionic resin and the cationic resin of the present invention is

[0031] a. from 80 wt % cationic resin and 20 wt % nonionic resin to 20 wt % cationic resin and 80 wt % nonionic resin,

[0032] b. from 70 wt % cationic resin and 30 wt % nonionic resin to 30 wt % cationic resin and 70 wt % nonionic resin,

[0033] c. from 60 wt % cationic resin and 40 wt % nonionic resin to 40 wt % cationic resin and 60 wt % nonionic resin, or

[0034] d. from 55 wt % cationic resin and 45 wt % nonionic resin to 45 wt % cationic resin and 55 wt % nonionic resin,

[0035] e. Wherein the weight % of cationic resin and nonionic resin are dry weight.

[0036] As used herein, "substantially nonionic latex resin" refers to a nonionic latex resin that is substantially free of acid monomers or monomers with anionic groups, and that may include an inoculum amount of anionic surfactant used in the inoculum stage of the polymerization process to control the particle size of the latex resin, as those terms are defined and used herein. Preferably, no acid monomers and no monomers with anionic groups are used in the polymerization of the nonionic resin.

[0037] Specific implementation methods of the preferred embodiment

[0038] While capable of locking in stains and minimizing their ability to migrate through paint films, cationic resins can cause water sensitivity problems such as loss of wet adhesion, reduced scrub resistance, and reduced blister resistance. The present invention solves this problem by blending cationic resins with novel stable nonionic resins. The stable nonionic resin compositions of the present invention are advantageously compatible with cationic resins and do not form grit or gels when blended with cationic resins.

[0039] U.S. Pat. No. 4,981,759 discloses that a nonionic acrylic resin can be obtained by (co)polymerizing at least one unsaturated monomer selected from alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate and 2-ethylhexyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; (meth)acrylic acid; aromatic vinyl compounds such as styrene and its derivatives (e.g., α-methylstyrene); (meth)acrylonitrile; and butadiene, depending on the desired properties.

[0040] Typical emulsion polymerizations (such as those described in the '759 patent) include acrylic, vinyl or styrene monomers, and a small amount of an acid monomer, such as (meth)acrylic acid, is added to stabilize the polymerization. Generally, in the absence of an acid monomer, the emulsion process is unstable and often unsuccessful. The inventors of the present invention have determined that the use of an acid monomer such as (meth)acrylic acid in the polymerization renders the resulting polymer anionic. Without being bound by any particular theory, it is believed that the side chains on the (meth)acrylic acid in the latex polymer lose protons and become anionic.

[0041] In a preferred embodiment of the present invention, acid monomers are omitted or substantially omitted from the polymerization to prevent these moieties from forming anions on the polymer. In order to impart stability to the nonionic polymer resin, hydrophilic and nonionic surfactants having relatively high HLB values ​​are used in the polymerization to seed or form micelles. A polymerizable nonionic hydrophilic component, such as polyethylene glycol or polypropylene glycol (e.g., methoxypolyethylene glycol methacrylate (molecular weight 750 Daltons, 50% in water)) may be optionally added to the polymerization. In order to control the particle size of the latex resin, a small amount of anionic surfactant is optionally used in the polymerization at the seeding stage. If used, such anionic surfactant is preferably the only ionic component in the polymerization and effectively provides seeds for the latex polymer.

[0042] The acid monomers preferably remain less than 0.25 wt%, preferably less than 0.125 wt%, and preferably less than 0.1 wt%, and more preferably 0 wt%.

[0043] The nonionic surfactant ranges from about 4 wt % to 8 wt %, preferably from about 5 wt % to 7 wt %, preferably from about 5.5 wt % to 6.5 wt %, and the nonionic surfactant has a hydrophile-lipophile balance (HLB) value of about 14 to about 18, preferably from about 14 to about 17, preferably from about 15 to about 18.

[0044] The optional anionic surfactant is preferably present at 0 wt% to about 0.25 wt%, preferably 0.01 wt% to about 0.25 wt%, preferably about 0.035 wt% to about 0.15 wt%, preferably about 0.05 wt% to about 0.15 wt%.

[0045] The optional nonionic polymerizable hydrophilic component is preferably present at 0 wt % to about 10 wt %, 0 wt % to about 5 wt %, or about 1.5 wt % to about 3.5 wt %. The nonionic polymerizable hydrophilic component can also be about 1.0 wt % to about 4.0 wt %. The nonionic polymerizable hydrophilic component can be omitted.

[0046] The percentages of nonionic resins described herein are given as weight percent active ingredients, including the weight of solid monomer and active ingredients of additives, excluding water.

[0047] An exemplary composition of the nonionic resin of the present invention without the acid monomer is shown below in Example 1. The weight percentages reported in this example do not include water. Typically, MPEG 750MA is available as a 50% aqueous solution, and the (meth)acrylate monomer is available as a 40-42 wt% solid in aqueous solution.

[0048] Example 1.

[0049]

[0050]

[0051] The glass transition temperature (Tg) of the nonionic resin ranges from about -5°C to about 5°C, with a typical value of 1°C calculated using Fox's equation. The minimum film forming temperature (MFFT) ranges from about -2°C to about 2°C, as determined by ISO 2115 standard. The particle size (average volume) is from about 155nm to about 175nm, and the pH is from about 5 to about 6. The number average molecular weight is 70,047 Daltons, and the weight average molecular weight is 243,139 Daltons, as measured by GPC (RI detector) using polystyrene standards.

[0052] Another exemplary composition of the nonionic resin of the present invention without the acid monomer is shown below in Example 2. The weight percentages reported in this example do not include water. The polymerizable hydrophilic nonionic component, e.g., MPEG (0 weight %) is omitted in this example.

[0053] Example 2

[0054]

[0055]

[0056] The amount of nonionic surfactant in Example 2 is about 2 times (2x) that in Example 1, 5.62 wt%, and the polymerizable hydrophilic nonionic component (MPEG) is reduced to zero.

[0057] In Example 3, the amount of nonionic surfactant is about 1.5 times that of Example 1, which is about 4.3 wt %, and the polymerizable hydrophilic nonionic component (MPEG) is reduced to about (1 / 2) times that of Example 1, which is about 1.38 wt %.

[0058] An exemplary paint composition utilizing a blend of the nonionic resin of the present invention and a commercially available cationic resin is shown below in Paint Example 4. The weight percentages given in Example 4 include water.

[0059] Paint Example 4.

[0060]

[0061]

[0062] The cationic resin contains about 57% water and the nonionic resin contains about 59% water. Therefore, the ratio of cationic resin to nonionic resin - dry weight - is (0.43x31.312):(0.41x22.166) or 13.46:9.09 or about 59.6:40.4 (or 60:40) cationic resin to nonionic resin. The total resin amount is about 22.55% solid resin (dry) in the total formula (including water). The rust inhibitor can range from 0% to about 1% by weight, preferably 0.15% to 0.5% by weight.

[0063] Paint Example 5 is similar to Paint Example 4, having a 60:40 blend ratio, except that the nonionic resin in Example 2 is used. Paint Example 6 is similar to Paint Example 4, having a 60:40 blend ratio, except that the nonionic resin in Example 3 is used.

[0064] The cationic resin used in these experiments was a commercial aqueous emulsion polymerized resin.

[0065] The blends shown in Paint Examples 4-6 do not form grit or gel when blended and therefore do not negatively impact the properties of the paint films formed from the blends.

[0066] In Experiment 7, various dried paint films from different paint / building combinations were tested on a cedar board surface with stain. Contrast ratio readings were taken on the stained and non-stained areas. A Δb* measurement was taken on the stained area of ​​each paint film. The dried paint films were also checked for blistering. The results are shown below.

[0067] Experiment 7.

[0068]

[0069] - C / R is the contrast ratio. The contrast ratio is the ratio of the Y value of the paint on the stained area divided by the lightness (Y) value of the paint color on the non-stained area. The best C / R score is theoretically 100.

[0070] - Δb* is a measure of yellowness by measuring the intensity of light of a specific wavelength (e.g., the wavelength of yellow) with a spectrophotometer. The higher the reading, the more stain there is.

[0071] - Blistering resistance was tested at 90°C and rated 1-5, with 1 being the worst.

[0072] Experiment 7 shows that Paints 4-6 have comparable tannin hiding or blocking properties to the baseline primer. When the polymerizable hydrophilic nonionic component is reduced or omitted, the blister resistance decreases. The inventors of the present invention note that the indoor blister resistance test is rigorously conducted at 90°C, which far exceeds the environmental conditions to which paints and other building compositions are exposed. Nevertheless, the high pass (5.0 point) of Inventive Paint 4 shows that the Inventive paints have enhanced resistance to blistering at elevated temperatures. The present invention is not limited to any blister score. Paints 5 and 6 are within the scope of the present invention because they exhibit good tannin resistance and do not form coarse particles or gels when blended with cationic and nonionic resins. These paints are commercially acceptable for applications that do not require exposure to such elevated temperatures.

[0073] Preferably, the blend of nonionic resin and cationic resin of the present invention ranges from 80 wt% cationic resin and 20 wt% nonionic resin to 20 wt% cationic resin and 80 wt% nonionic resin. The blend may also range from 70 wt% cationic resin and 30 wt% nonionic resin to 30 wt% cationic resin and 70 wt% nonionic resin. The blend may also range from 60 wt% cationic resin and 40 wt% nonionic resin to 40 wt% cationic resin and 60 wt% nonionic resin. The blend may also range from 55 wt% cationic resin and 45 wt% nonionic resin to 45 wt% cationic resin and 55 wt% nonionic resin.

[0074] Exemplary "cationic" resins include latex resins polymerized with commonly used (meth)acrylic monomers including styrene or vinyl acetate and one or more cationic monomers. Exemplary cationic monomers include one or more dimethylamino functional monomers, wherein the one or more dimethylamino functional monomers have the formula:

[0075]

[0076] wherein R1 represents hydrogen or methyl; R2 represents hydrogen or C1-6 alkyl, and n is 2 to 6.

[0077] Preferably, the dimethylamino monomers include N,N-dimethylaminoethyl methacrylate (DMAEMA), dimethylaminopropyl methacrylate (DMAPMA), butylaminoethyl methacrylate (TBAEMA) and N-[3-(dimethylamino)propyl]methacrylamide (DMAPMAA).

[0078] Other suitable "cationic" monomers include, but are not limited to, N,N-dimethylaminoethyl acrylate, N-2-N,N-dimethylaminoethyl methacrylamide, N-3-N,N-dimethylaminopropyl acrylamide, N-3-N,N-dimethylaminopropyl methacrylamide, N,N-diethylaminoethyl acrylate, N,N-diethylaminoethyl methacrylate, N-tert-butylaminoethyl acrylate, N-tert-butylaminoethyl methacrylate, N,N-dimethylaminopropyl acrylamide, N,N-diethylaminopropyl acrylamide, and N,N-diethylaminopropyl methacrylamide. Other suitable "cationic" monomers are disclosed in US 2014 / 0121146 (paragraph

[0042] ), US 2015 / 0374634 (paragraph

[0123] ), US 2009 / 0269406 (paragraph

[0034] ), US 7,319,117 (columns 11 and 17). These references are incorporated herein in their entirety.

[0079] Embodiment 4: Preparation of cationic acrylic latex emulsions containing 1 wt % and 3 wt % DMAPMAA.

[0080] Example 4 describes a method for producing a cationic latex emulsion. A 5-L glass reactor equipped with a mechanical stirrer and a condenser was used to incorporate the "cationic" functional monomer DMAPMAA into the resin through a semi-continuous MMA / BA emulsion copolymerization process. The reaction temperature was controlled by a water bath. The solution pH was maintained between 8 and 9. DMAPMAA was added to the last 20-50% of the pre-emulsion. The pre-emulsion was added at a constant feed rate over 4 hours, and the initiator solution was added at a constant feed rate over 4.5 hours. All polymerizations were performed at 80°C at 50% solid content (monomer mass relative to total reaction mass). DMAPMAA monomer accounts for approximately 1% or 3% by weight (or mass) of the total monomers. The preparation of the copolymer adhesive may or may not add 0.1-1% crosslinking agent.

[0081] The particle size of the resulting emulsion was 140-150 nm; the nonvolatile content was 50-51%. Table 1 describes non-inventive control and inventive compositions containing DMAPMAA monomer.

[0082] Composition of acrylic latex emulsions containing 1% and 3% DMAPMAA.

[0083]

[0084] Suitable nonionic surfactants include those available from Rhodia Solvay 2525,

[0085] Suitable free radical initiators include 4,4'-azobis(4-cyanovaleric acid) or C 12 H 16 N4O4 and sodium persulfate.

[0086] Suitable latex particles include, but are not limited to, acrylic acid, vinyl, vinyl-acrylic acid or styrene-acrylic acid polymers or copolymers. The latex particles coalesce and / or crosslink to form a paint film on a substrate. As shown in the embodiments herein, latexes made primarily of acrylic acid monomers are preferred for the present invention. Exemplary non-limiting monomers suitable for forming latex particles of the present invention are described below.

[0087] Generally speaking, any (meth)acrylic acid monomer can be used in the present invention. Suitable (meth)acrylic acid monomers include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, alkyl (meth)acrylates such as methyl (meth)acrylate, (meth)acrylic acid, wet adhesion monomers such as N-(2-methacryloyl)methacrylate, The preferred monomers include divinylbenzene, diacrylates, alkyl ...

[0088] Preferred monomers containing aromatic groups are styrene and α-methylstyrene. Other suitable monomers containing aromatic groups include, but are not limited to, 2,4-diphenyl-4-methyl-1-pentene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, 2,3,4,5,6-pentafluorostyrene, (vinylbenzyl)trimethylammonium chloride, 2,6-dichlorostyrene, 2-fluorostyrene, 2-isopropenylaniline, 3 (trifluoromethyl)styrene, 3-fluorostyrene, α-methylstyrene, 3-vinylbenzoic acid, 4-vinylbenzyl chloride, α-bromostyrene, 9-vinylanthracene, and combinations thereof.

[0089] Preferred monomers containing primary amide groups are (methyl) acrylamide. Suitable monomers containing amide groups include, but are not limited to, N-vinylformamide or any vinylamide, N,N-dimethyl (methyl) acrylamide, N-(1,1-dimethyl-3-oxobutyl) (methyl) acrylamide, N-(hydroxymethyl) (methyl) acrylamide, N-(3-methoxypropyl) (methyl) acrylamide, N-(butoxymethyl) (methyl) acrylamide, N-(isobutoxymethyl) acryl (methyl) acrylamide, N-[tris (hydroxymethyl) methyl] acryl (methyl) acrylamide, 7-[4-(trifluoromethyl) coumarin] (methyl) acrylamide, 3-(3-fluorophenyl)-2-acrylamide, 3-(4-methylphenyl) (methyl) acrylamide, N-(tert-butyl) (methyl) acrylamide and combinations thereof. These monomers can be polymerized with the acrylic monomers listed above. The general formula of vinyl (formamide) is:

[0090]

[0091] And the general formula of (meth)acrylamide is:

[0092]

[0093] Wherein R1 and R2 can be -H, -CH3, -CH2CH3 and other substituted organic functional groups, and R3 can be -H, alkyl or aryl.

[0094] In one embodiment, styrene monomers, such as styrene, methylstyrene, chlorostyrene, methoxystyrene, and the like, are preferably copolymerized with (meth)acrylamide monomers.

[0095] In one embodiment, the aqueous latex polymer may also contain a vinyl monomer. Monomers of this type suitable for use according to the present invention include any compound having a vinyl functional group (i.e., a -CH=CH2 group). Preferably, the vinyl monomer is selected from the group consisting of vinyl esters, vinyl aromatic hydrocarbons, vinyl aliphatic hydrocarbons, vinyl alkyl ethers, and mixtures thereof.

[0096] Suitable vinyl monomers include vinyl esters such as, for example, vinyl acetate, vinyl propionate, vinyl laurate, vinyl pivalate, vinyl nonanoate, vinyl decanoate, vinyl neodecanoate, vinyl butyrate, vinyl hexanoate, vinyl benzoate, vinyl isopropyl acetate and similar vinyl esters; nitrile monomers such as (meth) acrylonitrile and the like; vinyl aromatics such as, for example, styrene, methyl styrene and similar lower alkyl styrenes, chlorostyrene, vinyl toluene, vinyl naphthalene and divinylbenzene; vinyl aliphatic hydrocarbon monomers such as, for example, vinyl chloride and vinylidene chloride, and alpha olefins such as, for example, ethylene, propylene, isobutylene, and conjugated dienes such as 1,3-butadiene, methyl-2-butadiene, 1,3-pentylene, 2,3-dimethylbutadiene, isoprene, cyclohexene, cyclopentadiene and dicyclopentadiene; and vinyl alkyl ethers such as, for example, methyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether and isobutyl vinyl ether.

[0097] Additives may be added to the polymerization process including surfactants, initiators, chaser solutions, biocides, rheology modifiers, and the like.

[0098] JV Koleske, R. Springate, and D. Brezinski describe surfactants in the Additives Reference Guide, pp. 83-88 (2013), and these pages are incorporated herein in their entirety. The following discussion of surfactants is based on Koleske et al.

[0099] Nonionic surfactants usually refer to polyoxyethylene derivatives, although other surfactants also belong to this class. They are usually prepared by the addition reaction of ethylene oxide with a hydrophobic compound containing one or more active hydrogen atoms. Examples of such hydrophobic compounds are fatty alcohols, alkylphenols, fatty acids, fatty amines, alkanolamines, fatty mercaptans, fatty amines and certain polyols. The polyols may include oxypropylene polyols, polyesters, etc. These surfactants are uncharged and will not dissociate. Their surface active characteristics come from the oxyethylene portion of the molecule. The nature of the hydrophobe and the length of the oxyethylene chain both affect the surface active characteristics.

[0100] In general, these groups are weakly hydrophilic compared to the hydrophobic part of the molecule. Weak ester bonds and amide bonds are also present in many nonionic surfactants. Nonionic surfactants are generally compatible with ionic surfactants. For example, many nonionic surfactants work well with anionic surfactants. In such a combination, they give aqueous systems good freeze-thaw stability and are less detrimental to mechanical properties than ionic compounds. Nonylphenol ethoxylate (NPE) is a typical example of such a surfactant. Other examples are: octylphenol ethoxylate (OPE), secondary alcohol ethoxylates, trimethylnonanol ethoxylate (TMN), specialty alkoxylates, and amine ethoxylates. In emulsion polymerization, alkyl ether sulfates are one of the main surfactants necessary to provide micelle stabilization. Traditionally, these sulfates have been based on alkylphenol ethoxylates (APEO). Typically, emulsion polymerization uses two types of surfactants - one nonionic and the other anionic. Each provides a separate stabilization mechanism for micelles, but the combination provides better stabilization, especially as temperature increases. Nonionic surfactants create spatial separation between micelle groups, while anionic surfactants create charged repulsion between micelles. Nonionic surfactants generally perform well over a range of pH values, and their foams are generally smaller than anionic and cationic surfactants. However, in complex coating formulations, nonionic surfactants may not reduce surface tension as well as anionic or cationic surfactants. There are nonionic polymeric fluorochemical surfactants that can provide low surface tension in organic coating systems. The lower the surface tension, the better the coating wetting, leveling and spreading. Therefore, these are excellent wetting agents, leveling agents and flow control agents for a variety of water-based, solvent-based and high-solid coating systems. Most fluorosurfactants are soluble and compatible with most polymers and continue to be active throughout the drying or curing process. When used in water-based systems, they tend to reduce the water / organic interfacial tension and remain surface active in the organic part of the polymer system. There is also an anionic fluorosurfactant based on ammonium salts on the market that is soluble in water.

[0101] Anionic surfactants carry a negative charge on the hydrophilic portion of the molecule. They are typically phosphates, sulfates, and sulfonates. These surfactants may or may not contain oxyethylene chains in their structure. Examples of anionic surfactants are sulfosuccinates, dioctyl sulfosuccinate (DOSS), polyether sulfates, polyether sulfonates, polyether phosphates, sodium lauryl sulfate, and phosphate-modified alcohol-ethoxylates.

[0102] Surface-active phosphates are a class of anionic surfactants prepared by the reaction of alcohols with activated phosphoric acid derivatives (including phosphoric anhydride and acid chloride). Typically, commercial phosphate products consist of a mixture of monoesters, diesters, free phosphoric acid and free alcohols used in their preparation. The properties of the final phosphate product are primarily determined by the composition of the starting alcohol used and the four different substances. On the contrary, the properties of the final phosphate product can be customized by changing the alcohol used in the preparation and controlling the ratio of the four different components present in the final product. Phosphate surfactants are made in free acid form, but can also be neutralized to a salt form using any alkali (including sodium hydroxide, potassium hydroxide, ammonium hydroxide or any organic amine).

[0103] Typically, phosphate ester surfactants are added to the formulation during the paint preparation process - either at the grind or at letdown, depending on the formulation. These additives have also been tested as post-paint formulation additives and have shown comparable properties. It is presumed, and the focus of much research, that the use of phosphate ester surfactants prior to the paint formulation stage (using phosphate esters in emulsion polymerization and post-polymerization stabilizers or additives in pigment dispersion) should only benefit the final properties of the paint and reduce the deleterious effects of additional surfactants in the paint system.

[0104] Cationic surfactants carry a positive charge, and quaternary ammonium compounds are the most common cationic surfactants. Compounds such as alkyltrimethylammonium chloride are representatives of these surfactants.

[0105] The hydrophilic lipophilic balance (HLB) system is a numbering system for evaluating the relative hydrophilicity of surfactants. The system is based on an arbitrary numerical scale, wherein zero is designated as a surfactant of extreme hydrophobicity, and 20 is designated as a surfactant of extreme hydrophilicity. The numbers assigned to a surfactant represent a measure of the balance between its hydrophilic strength and hydrophobic strength. A surfactant with an HLB of 10 has a balance of lipophilic and hydrophilic groups.

[0106] Examples of initiator and chaser solutions useful in the polymerization process may include, but are not limited to, ammonium persulfate, sodium persulfate, azo initiators (such as azoisobutyronitrile), redox systems (such as sodium hydroxymethanesulfinate (sodium formaldehyde sulfoxylate; reducing agent) and tert-butyl-hydroperoxide (oxidizing agent)), and the like, and combinations thereof, typically in aqueous solution. Either or both of these components may optionally contain additional surfactants and / or pH adjusters if desired to stabilize the emulsion.

[0107] Examples of pH adjusters useful in the polymerization process may include, but are not limited to, ammonium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, ammonia, amines such as trimethylamine, triethylamine, dimethylaminoethanol, diethylaminoethanol, AMP-95, and the like, and combinations thereof. In some cases, compounds considered to be pH adjusters may be added for purposes other than adjusting pH, such as emulsion stabilization, but are still characterized herein as pH adjusters.

[0108] Polymer molecular weight controllers are intended to control (usually limit) the molecular weight of a growing polymer. Although polymer molecular weight controllers may include substances such as radiation, they are typically molecules added to a polymerization mixture. Examples of polymer molecular weight controllers include, but are not limited to, chain transfer agents (CTAs), for example, alkyl mercapto esters such as isooctyl mercaptopropionate, alkyl mercaptans, etc., and combinations thereof. Chain transfer agents typically act as polymer molecular weight controller molecules, for example, catalytically or consumably terminating growing polymer chains by also initiating new growing polymer chains. In this way, the amount of chain transfer agents can be adjusted to reduce the target polymer molecular weight in a set of polymerization systems, or alternatively, in combination with calculating the amount of initiator, the amount of chain transfer agents can be calculated to target a specific average polymer molecular weight (e.g., within a given range) of a polymerization system.

[0109] Although the exemplary embodiments of the present invention disclosed herein obviously achieve the above-mentioned purpose, it should be understood that those skilled in the art can design numerous modifications and other embodiments. Therefore, it should be understood that the appended claims are intended to cover all such modifications and embodiments, which will fall within the spirit and scope of the present invention.

Claims

1. A substantially nonionic latex resin composition polymerized from: A monomer mixture comprising at least one nonionic (meth)acrylate monomer, wherein the monomer mixture is substantially free of acid monomers or other monomers with anionic groups, and a nonionic surfactant ranging from about 4 wt% to 8 wt%, preferably from about 5 wt% to 7 wt%, preferably from about 5.5 wt% to 6.5 wt%, wherein the nonionic surfactant has a hydrophile-lipophile balance (HLB) value of about 14 to about 18, preferably from about 14 to about 17, preferably from about 15 to about 18, The weight percentages stated do not include water.

2. The substantially nonionic latex resin composition of claim 1, which is additionally polymerized with an inoculum amount of anionic surfactant, wherein the inoculum amount ranges from 0 wt % to about 0.25 wt %, preferably from 0.01 wt % to about 0.25 wt %, preferably from about 0.05 wt % to about 0.15 wt %, based on the total monomer content.

3. The substantially nonionic latex resin composition of claim 1, wherein the monomer mixture does not contain acid monomers or other monomers having anionic groups.

4. The substantially nonionic latex resin composition of claim 1, wherein the acid monomer or other monomer with an anionic group is less than 0.25 wt. %, preferably less than 0.125 wt. % of the total monomer content.

5. The substantially nonionic latex resin composition of claim 1, wherein the monomer mixture further comprises a polymerizable nonionic hydrophilic component, wherein the polymerizable nonionic hydrophilic component is preferably present in an amount of 0 wt % to about 10 wt %, 0 wt % to about 5 wt %, about 1.0 wt % to about 4.0 wt %, or about 1.5 wt % to about 3.5 wt %, and The nonionic surfactant is present in an amount ranging from about 1 wt % to about 3.5 wt %, or from about 1 wt % to about 3.0 wt %.

6. The substantially nonionic latex resin composition of claim 5, wherein the polymerizable nonionic hydrophilic component comprises a polymerizable polyethylene glycol monomer or a polymerizable polypropylene glycol monomer.

7. The substantially nonionic latex resin composition of claim 6, wherein the polymerizable polyethylene glycol monomer is a methoxy polyethylene glycol methacrylate monomer.

8. The substantially nonionic latex resin composition of claim 1, wherein only nonionic surfactant is used in the polymerization to form micelles and the substantially nonionic latex resin.

9. A paint composition, preferably a primer or topcoat composition, comprising a blend of the substantially nonionic latex resin composition of any one of claims 1 to 8 and a cationic resin.

10. The paint composition of claim 9, further comprising a rust inhibitor.

11. The paint composition of claim 9, wherein the blend of said substantially nonionic resin and said cationic resin ranges from 80 wt. % cationic resin and 20 wt. % nonionic resin to 20 wt. % cationic resin and 80 wt. % nonionic resin, The weight % of cationic resin and nonionic resin are dry weight.

12. The paint composition of claim 9, wherein the blend of the substantially nonionic resin and the cationic resin ranges from 70 wt. % cationic resin and 30 wt. % nonionic resin to 30 wt. % cationic resin and 70 wt. % nonionic resin, The weight % of cationic resin and nonionic resin are dry weight.

13. The paint composition of claim 9, wherein the blend of said substantially nonionic resin and said cationic resin ranges from 60 wt % cationic resin and 40 wt % nonionic resin to 40 wt % cationic resin and 60 wt % nonionic resin, The weight % of cationic resin and nonionic resin are dry weight.

14. The paint composition of claim 9, wherein the blend of said substantially nonionic resin and said cationic resin ranges from 55 wt. % cationic resin and 45 wt. % nonionic resin to 45 wt. % cationic resin and 55 wt. % nonionic resin, The weight % of cationic resin and nonionic resin are dry weight.

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