JP5132987B2 - Water resistant emulsion composition - Google Patents

Description

  The present invention relates to a water resistant emulsion composition. More specifically, viscosity stability and a water-based emulsion having a specific vinyl alcohol polymer as a protective colloid and a copolymer of a specific acrylic acid and an acetal group-containing ethylenically unsaturated monomer as main components. The present invention relates to a water-resistant emulsion composition that is excellent in water resistance (boiling resistance) and also in safety.

  Polyvinyl alcohol polymers (hereinafter sometimes abbreviated as PVA) are widely used as protective colloids for emulsion polymerization of ethylenically unsaturated monomers, particularly vinyl ester monomers represented by vinyl acetate. Yes. Vinyl ester aqueous emulsions obtained by emulsion polymerization of vinyl ester monomers using PVA as protective colloid are various adhesives for paper, woodwork and plastics, impregnated paper and non-woven products, etc. Are widely used in the fields of binders, admixtures, jointing materials, paints, paper processing and fiber processing. Such an aqueous emulsion exhibits a useful effect in the above-mentioned various uses by forming a film having strong mechanical strength under dry conditions. However, under high humidity or water wet conditions, Since the PVA forming the water is water-soluble, there is a problem that the elution and water absorption of the PVA are large and the mechanical strength is remarkably lowered.

For this reason, various means have been tried so far in order to increase the water resistance and hot water resistance of a film obtained from an emulsion using PVA as a protective colloid. As a typical example, a method in which a polyvalent isocyanate compound is blended with an emulsion using PVA as a protective colloid is known. In this method, since the isocyanate compound reacts strongly with the hydroxyl group of PVA and the like, remarkable water resistance is exhibited. On the other hand, since the isocyanate compound also reacts with water, the pot life of the emulsion is very short and workability is improved. There is a problem.
In view of the above, various proposals have been made on adhesives using aqueous emulsions in which PVA is a protective colloid. For example, (1) an aqueous emulsion using PVA as a dispersant, and an adhesive comprising an aliphatic aldehyde such as glyoxal (Patent Document 1), (2) an amino compound such as PVA, an aqueous emulsion, a crosslinking agent, and chitosan Adhesives (Patent Document 2), (3) Crosslinking agents such as PVA, aqueous emulsion, aluminum chloride, and adhesives composed of polyvalent isocyanate compounds (Patent Document 3), (4) α-olefin units having 4 or less carbon atoms An adhesive mainly composed of an emulsion containing PVA as a dispersant (Patent Document 4), (5) an emulsion obtained by emulsion polymerization in the presence of a carboxyl group-modified PVA, a reaction product of a polyamide and an epoxy group-containing compound Composition (Patent Document 5), (6) PVA polymer having an α-olefin unit in the molecule and carbo Known is an aqueous emulsion having a PVA polymer having a xyl group as a dispersant, an epoxy compound, an amino group-containing aqueous resin, a composition comprising a water-resistant agent selected from an aluminum compound and a titanium compound (Patent Document 6). Yes.
However, the adhesives of (1), (2), (4), (5) and (6) are not necessarily sufficient in terms of boiling resistance, although an effect of improving water resistance is observed. Further, the adhesive (3) has poor viscosity storage stability (that is, the pot life is short), and there is a problem in workability. Therefore, it is not an exaggeration to say that there are no aqueous dispersions, compositions, adhesives and coating agents that have both high water resistance, particularly boiling resistance and viscosity storage stability, at the current technical level. There is room for improvement.

Japanese Patent Laid-Open No. 55-094937 Japanese Patent Laid-Open No. 03-045678 Japanese Patent Publication No.57-016150 Japanese Patent Application Laid-Open No. 08-081664 Japanese Patent Laid-Open No. 06-128495 Japanese Patent Laid-Open No. 2001-040231

  An object of the present invention is to provide a water-resistant emulsion composition that eliminates the above-mentioned drawbacks of the prior art, is excellent in viscosity stability and water resistance, and is also excellent in safety.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors made PVA (a) having a vinyl alcohol unit of 85 mol% or more as a dispersant, an ethylenically unsaturated monomer and a diene unsaturated monomer. An aqueous emulsion (A) having polymer fine particles (b) composed of at least one monomer unit selected from a polymer as a dispersoid, and copolymerization of acrylic acid and an acetal group-containing ethylenically unsaturated monomer The resulting polyacrylic acid-based copolymer (B) containing 5 to 40 mol% of a unit derived from the acetal group-containing ethylenically unsaturated monomer, and the ratio of (A) to (B) (A ): (B) was found that a water-resistant emulsion composition having a solid content weight ratio of 100: 1 to 100: 20 solves the above-mentioned problems of the present invention, and has completed the present invention.

  The water-resistant emulsion composition of the present invention has high safety because it does not contain harmful components, has excellent storage stability, and has extremely high water resistance and boiling resistance.

  The PVA (a) used in the present invention is not particularly limited as long as it has 85 mol% or more of vinyl alcohol units, but is preferably 86 to 99.9 mol%, and 86.5 to 99.6 mol% is more preferable, and 87-99.5 mol% is further more preferable. If the vinyl alcohol unit is less than 85 mol%, the resulting emulsion composition has insufficient water resistance.

  The degree of polymerization of PVA (a) is not particularly limited as long as the characteristics of the present invention are not impaired, but is generally 200 to 4000, more preferably 300 to 3500, and particularly preferably 350 to 3000. When PVA having a degree of polymerization of less than 200 is used, the viscosity stability of the resulting emulsion composition may be lowered. On the other hand, when the degree of polymerization exceeds 4000, industrial production becomes difficult. Polymerization stability may be reduced. In addition, the polymerization degree here means the average polymerization degree calculated | required by the method described in JIS-K6726.

  As PVA (a), usually a vinyl ester monomer typified by vinyl acetate is polymerized by various methods (bulk polymerization, solution polymerization using methanol as a solvent, emulsion polymerization, suspension polymerization, etc.). PVA obtained by saponification by a conventional method is used. In addition to vinyl acetate, vinyl formate, vinyl propionate, vinyl versatate, vinyl pivalate, and the like can be used as the vinyl ester monomer.

In addition, PVA (a) can be copolymerized by allowing a monomer that can be copolymerized with a vinyl ester monomer to coexist as long as the effects of the present invention are not impaired. Examples of the copolymerizable monomer include olefins such as ethylene, propylene, 1-butene and isobutene, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate and acrylic. Acrylic acid esters such as n-butyl acid, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylic acid Methacrylic acid esters such as i-propyl, n-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, methyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ester Ter, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, vinyl ethers such as dodecyl vinyl ether, stearyl vinyl ether, nitriles such as acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride Allyl compounds such as vinyl halides such as allyl acetate, allyl chloride, etc., fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimetic anhydride, itaconic anhydride and other carboxyl group-containing compounds and esters thereof Sulfonic acid group-containing compounds such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, diacetone acrylamide, diacetone acrylate, di Diacetone group-containing compounds such as seton methacrylate, vinyl silane compounds such as vinyltrimethoxysilane, isopropenyl acetate, 3-acrylamidopropyltrimethylammonium chloride, 3-methacrylamidopropyltrimethyl ammonium chloride.
Further, a terminal modified product obtained by polymerizing a vinyl ester monomer such as vinyl acetate in the presence of a thiol compound such as thiol acetic acid or mercaptopropionic acid and saponifying it can also be used.

  Moreover, PVA (a) can also use modified PVA which modified | denatured conventionally well-known PVA by post-reaction in the range which maintains water solubility and does not impair the effect of this invention. Examples of the PVA modified by the post reaction include various acetalized PVA modified with an aldehyde such as butyraldehyde, acetoacetyl group-modified PVA modified with diketene, and the like.

  As PVA (a), various types having 85 mol% or more of vinyl alcohol units as described above can be used. In particular, ethylene-modified PVA containing 2 to 8 mol% of an ethylene-derived unit, and an acetoacetyl group When the modified PVA is used, a water-resistant emulsion composition that is particularly excellent in viscosity stability and water-resistant adhesion, which are the objects of the present invention, is obtained.

  When ethylene-modified PVA is used as PVA (a), the amount of modification with ethylene is preferably 2 to 8 mol%, and more preferably 2 to 7.5 mol%. When the modification amount is less than 2 mol%, the water resistance may not be remarkably improved, and when it exceeds 8 mol%, the viscosity stability may decrease.

  When acetoacetyl-modified PVA is used as PVA (a), the amount of modification with acetoacetyl groups is preferably 2 to 8 mol%, more preferably 2 to 7.5 mol%. When the modification amount is less than 2 mol%, the water resistance may not be remarkably improved, and when it exceeds 8 mol%, the viscosity stability may decrease.

  The water-based emulsion (A) constituting the water-resistant emulsion composition of the present invention comprises the above-described PVA (a) having a vinyl alcohol unit of 85 mol% or more as a dispersant, an ethylenically unsaturated monomer and a diene-based unsaturated. Polymer fine particles (b) composed of at least one monomer unit selected from monomers are used as dispersoids. Here, the polymer fine particles (b) comprising at least one monomer unit selected from an ethylenically unsaturated monomer and a diene unsaturated monomer include an ethylenically unsaturated monomer and a diene unsaturated monomer. It can be obtained by polymerizing at least one monomer selected from saturated monomers by various methods and, in some cases, by making fine particles. Generally, PVA (a) is used as a dispersant, and ethylenic properties are obtained. A method in which at least one monomer selected from unsaturated monomers and diene monomers is emulsion-polymerized in an aqueous medium allows the aqueous emulsion (A) of the present invention to be obtained industrially in one step. Is preferable.

  Examples of the ethylenically unsaturated monomer and diene unsaturated monomer constituting the polymer fine particles (b) include olefins such as ethylene, propylene, and isobutylene, vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride, and the like. Halogenated olefins, vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl versatic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 2-hydroxy acrylate Acrylic esters such as ethyl, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate and 2-hydroxyethyl methacrylate, dimethyl acrylate Acrylamide monomers such as ruaminoethyl, dimethylaminoethyl methacrylate and quaternized products thereof, acrylamide, methacrylamide, N, N-dimethylacrylamide, acrylamide-2-methylpropanesulfonic acid and its sodium salt, styrene , Α-methylstyrene, p-styrenesulfonic acid and styrene monomers such as sodium and potassium salts, other N-vinylpyrrolidone, and diene monomers such as butadiene, isoprene and chloroprene. In addition, monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, (anhydrous) maleic acid, (anhydrous) phthalic acid, and cinnamic acid may be used as they are or as sodium salts. It can be used in the form of a neutralized product or a half ester. Monomers having a methylol group or alkoxymethyl group such as N-methylolacrylamide, N-methylolmethacrylamide, N-butoxymethylacrylamide, N-butoxymethylmethacrylamide, monomers having a diacetone group such as diacetoneacrylamide, Monomers having acetoacetyl groups such as acetoacetoxyethyl acrylate and acetoacetoxyethyl methacrylate, monomers having alkoxysilane groups such as vinyltrimethoxysilane and methacryloxypropyltrimethoxysilane, glycidyl methacrylate, allyl glycidyl ether Monomers having an epoxy group such as, monomers having an oxazoline group such as vinyl oxazoline and 2-propenyl-2-oxazoline do not impair the effects of the present invention. It can be used in a range. Among the above unsaturated monomers, vinyl ester monomers, ethylene and vinyl ester monomers and vinyl esters and (meth) acrylic acid ester monomers are preferred, from an industrial viewpoint. As the vinyl ester monomer, vinyl acetate is particularly preferable.

  As described above, the method for obtaining the aqueous emulsion (A) in the present invention includes one or more selected from the above ethylenically unsaturated monomers and diene monomers in an aqueous medium in the presence of PVA (a). A method of emulsion polymerization of monomer units is preferred. In this case, conventionally known conditions for emulsion polymerization are employed for the temperature, pressure, stirring speed and the like. The addition of the monomer is performed by initial batch addition, continuous addition, monomer pre-emulsification liquid addition (continuous addition of a monomer emulsified in a dispersion stabilizer aqueous solution) or the like. As the initiator, conventionally known initiators such as hydrogen peroxide, potassium persulfate, and ammonium persulfate are used, and in some cases, redox initiators in combination with a reducing agent such as tartaric acid, L-ascorbic acid, Rongalite, etc. Can also be used. The average particle diameter of the polymer fine particles (b) is generally 0.05 to 10 μm, and 0.1 to 5 μm is preferable as a range that does not impair the viscosity stability and the like.

  In the aqueous emulsion (A) used in the present invention, the amount of PVA (a) present in the aqueous phase of the emulsion is 8% by weight from the viewpoint of obtaining a water-resistant emulsion composition having good viscosity stability and water-resistant adhesion. % Or less, and more preferably 2 to 7% by weight. The amount of PVA present in the emulsion aqueous phase is measured by various methods such as gravimetric method and iodine coloration method by measuring the concentration of PVA in the supernatant after centrifuging the aqueous emulsion and precipitating the dispersoid. Can be obtained.

  The water-resistant emulsion composition of the present invention is an acetal group-containing ethylenically unsaturated monomer obtained by copolymerization of the aqueous emulsion (A), acrylic acid and an acetal group-containing ethylenically unsaturated monomer. A polyacrylic acid copolymer (hereinafter sometimes abbreviated as “PAA”) (B) containing 5 to 40 mol% of the unit derived from the above. PAA (B) needs to contain 5 to 40 mol% of units derived from an acetal group-containing ethylenically unsaturated monomer (sometimes abbreviated as acetal modification amount), preferably 5 to 35 mol. %, More preferably 5 to 30 mol%. When the acetal modification amount is less than 5 mol%, the effect of using the acetal group-containing ethylenically unsaturated monomer may not be sufficiently exhibited. When the acetal modification amount exceeds 40 mol%, PAA (B) And the compatibility of the aqueous emulsion (A) and the viscosity stability of the composition may be reduced.

The amount of acetal modification of PAA (B) can be determined from proton NMR. As an acetal group-containing ethylenically unsaturated monomer, to explain how to determine the acetal-modified amount as an example PAA obtained when using N-2,2-dimethoxyethyl (meth) acrylamide, the PAA D ₂ Dissolve in O and measure proton NMR at room temperature using 500 MHz proton NMR (JEOL GX-500). As a result of the measurement, the peak α (2.0 to 2.4 ppm) derived from the main chain methine of acrylic acid and the peak β (4.1 to 4.5 ppm derived from methine of —CH— (OCH ₃ ) ₂ are obtained. ), The acetal modification amount is calculated using the following formula.
Acetal modification amount (mol%) = {number of protons of β / (number of protons of α + number of protons of β)} × 100

  The molecular weight of PAA (B) is preferably 1,000 to 1,000,000. When the molecular weight exceeds 1,000,000, the water solubility of the PAA copolymer may decrease.

  The acetal-containing ethylenically unsaturated monomer used for the production of PAA (B) can be used as long as it is an ethylenically unsaturated monomer containing an acetal group. The ethylenically unsaturated monomer is preferably used.

（式中、Ｒ１は水素原子または−ＣＯＯＭであり、ここでＭは水素原子、アルカリ金属またはアンモニウム基を意味し、Ｒ２は水素原子、メチル基または−ＣＨ_２−ＣＯＯＭであり、ここでＭは前記定義のとおりであり、Ｒ３およびＲ４は同一または異なりそれぞれ炭素数１〜４の飽和アルキル基であり、Ｘは−ＣＯ−、−ＣＯ−Ｏ−または−ＣＯ−ＮＲ５であり、ここでＲ５は水素原子または炭素数１〜４の飽和アルキル基を意味し、ｎは１〜８の整数である。）

(Wherein R1 represents a hydrogen atom or —COOM, wherein M represents a hydrogen atom, an alkali metal or an ammonium group; R2 represents a hydrogen atom, a methyl group or —CH ₂ —COOM, where M represents As defined above, R 3 and R 4 are the same or different and each is a saturated alkyl group having 1 to 4 carbon atoms, X is —CO—, —CO—O— or —CO—NR 5, wherein R 5 is A hydrogen atom or a C1-C4 saturated alkyl group is meant, and n is an integer of 1-8.)

Specific examples of the acetal-containing ethylenically unsaturated monomer include N-2,2-dimethoxyethyl acrylamide, N-2,2-diethoxyethyl acrylamide, N-2,2-diisopropoxyethyl acrylamide, N- 2,2-dibutoxyethyl acrylamide, N-2,2-di-t-butoxyethyl acrylamide, N-2,2-dimethoxyethyl methacrylamide, N-2,2-diethoxyethyl methacrylamide, N-2, 2-diisopropoxyethyl methacrylamide, N-2,2-dibutoxyethyl methacrylamide, N-2,2-di-t-butoxyethyl methacrylamide, N-3,3-dimethoxypropyl acrylamide, N-3, 3-diethoxypropylacrylamide, N-3,3-diisopropoxypropylacrylic N-3,3-dibutoxypropyl acrylamide, N-3,3-di-t-butoxypropyl acrylamide, N-3,3-dimethoxypropyl methacrylamide, N-3,3-diethoxypropyl methacrylamide, N-3,3-diisopropoxypropyl methacrylamide, N-3,3-dibutoxypropyl methacrylamide, N-3,3-di-t-butoxypropyl methacrylamide, N-4,4-dimethoxybutyl acrylamide, N-4,4-diethoxybutylacrylamide, N-4,4-diisopropoxybutylacrylamide, N-4,4-dibutoxybutylacrylamide, N-4,4-di-t-butoxybutylacrylamide, N- 4,4-dimethoxybutylmethacrylamide, N-4,4-diethoxybutylmeta Rilamide, N-4,4-diisopropoxybutyl methacrylamide, N-4,4-dibutoxybutyl methacrylamide, N-4,4-di-t-butoxybutyl methacrylamide, N-methyl-N-2, 2-dimethoxyethyl acrylamide, N-methyl-N-2,2-diethoxyethyl acrylamide, N-methyl-N-2,2-diisopropoxyethyl acrylamide, N-methyl-N-2,2-dibutoxyethyl Acrylamide, N-methyl-N-2,2-di-t-butoxyethyl acrylamide, N-methyl-N-2,2-dimethoxyethyl methacrylamide, N-methyl-N-2,2-diethoxyethyl methacrylamide N-methyl-N-2,2-diisopropoxyethyl methacrylamide, N-methyl-N-2,2-dibutoxy Ciethyl methacrylamide, N-methyl-N-2,2-di-t-butoxyethyl methacrylamide, 4-{(2,2-dimethoxyethyl) amino} -4-oxo-2-butenoic acid, 4- { (2,2-diethoxyethyl) amino} -4-oxo-2-butenoic acid, 4-{(2,2-diisopropoxyethyl) amino} -4-oxo-2-butenoic acid, 4-{( 2,2-dibutoxyethyl) amino} -4-oxo-2-butenoic acid, 5,5-dimethoxy-3-oxo-pentene, 5,5-diethoxy-3-oxo-pentene, 5,5-diiso Propoxy-3-oxo-pentene, 5,5-dibutoxy-3-oxo-pentene, 4-{(2,2-dimethoxyethyl) amino} -4-oxo-3-methylene-butanoic acid, 4-{(2 , 2-Diethoxyethyl) a No} -4-oxo-3-methylene-butanoic acid, 4-{(2,2-diisopropoxyethyl) amino} -4-oxo-3-methylene-butanoic acid, 4-{(2,2-di Butoxyethyl) amino} -4-oxo-3-methylene-butanoic acid, 2,2-dimethoxyethyl acrylate, 2,2-diethoxyethyl acrylate, 2,2-diisopropoxyethyl acrylate, 2,2-dibutoxy Although ethyl acrylate etc. are mentioned, it is not limited to these.
In the above formula (1), R1 is preferably a hydrogen atom, R2 is preferably a hydrogen atom or a methyl group, R3 and R4 are preferably both methyl groups, and X is —CO—N ( H)-or -CO-N (CH3)-is preferred. Further, n is preferably 1 or 2, and more preferably 1.
Further, in the above formula (1), R 1 is a hydrogen atom, R 2 is a hydrogen atom or a methyl group, R 3 and R 4 are both methyl groups, and X is —CO—N (H) — or —CO It is more preferably —N (CH 3) — and n is 1.

  As a polymerization method used for copolymerizing acrylic acid and an acetal group-containing ethylenically unsaturated monomer, any of batch polymerization method, semi-batch polymerization method, continuous polymerization method and semi-continuous polymerization method can be used. It may be adopted. As the polymerization method, any known method such as a bulk polymerization method or a solution polymerization method can be used. Among these, the solution polymerization method is preferably employed. As the initiator used for copolymerization, conventionally known azo initiators, peroxide initiators, redox initiators and the like are appropriately selected according to the polymerization method. As the azo initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4- Dimethyl valeronitrile) and the like. Peroxide compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate; t-butyl Perester compounds such as peroxyneodecanate, α-cumylperoxyneodecanate, t-butylperoxydecanate; acetylcyclohexylsulfonyl peroxide; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, etc. Is mentioned. Further, the initiator may be combined with potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like. Examples of the redox initiator include a combination of the above-described peroxide and a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, or longalite.

  Moreover, in order to express the viscosity stability and water resistance which are the objectives of the water-resistant emulsion composition of the present invention, the solid content weight ratio (A) :( B) of the water-based emulsion (A) and PAA (B). Is in the range of 100: 1 to 100: 20. The weight ratio of the component (A) to the component (B) is preferably 100: 1.5 to 100: 18, and more preferably 100: 2 to 100: 15. When (A) :( B) = 100: 1 has less component (B), water resistance is not sufficiently developed, and (A) :( B) = when component (B) is more than 100: 20 , Viscosity stability decreases.

  When the water-resistant emulsion composition of the present invention is used in combination with a water-soluble polyvalent metal salt, the water-resistant adhesive property is particularly improved. Various kinds of polyvalent metal salts can be used, and water-soluble aluminum salts such as aluminum chloride and aluminum nitrate, water-soluble zirconium salts such as ammonium zirconium carbonate, and water-soluble titanium compounds are used. Among these, water-soluble aluminum salts are excellent in terms of water resistance. The blending amount of the polyvalent metal salt is preferably 5% by weight or less per solid content of the water-resistant emulsion composition, and when it exceeds 5% by weight, the viscosity stability of the composition is lowered.

  Various additives can be added to the water-resistant emulsion composition of the present invention as necessary. Typical examples are various organic solvents such as toluene, perchlene, dichlorobenzene and trichlorobenzene, various plasticizers such as dibutyl phthalate, various film-forming aids such as glycol ethers, kaolinite, halloysite, pyroferrite, selenium. Clay such as site, inorganic fillers such as heavy, light, or surface treated calcium carbonate, aluminum hydroxide, aluminum oxide, gypsum, talc, titanium oxide, organic such as starch, oxidized starch, wheat flour, wood powder Fillers, metal salts of phosphoric acid compounds such as sodium polyphosphate and sodium hexametaphosphate, inorganic dispersants such as water glass, polyacrylic acid and its salts, sodium alginate, α-olefin-maleic anhydride copolymer, etc. Anionic polymer compounds and their metal salts, higher alcohol ethylene Nonionic surfactant such as oxide adduct, copolymer of ethylene oxide and propylene oxide, anionic surfactant, cationic surfactant, amphoteric surfactant, carboxymethylcellulose, methylcellulose, sodium alginate, polyethylene oxide, polyvinyl Alcohol, various antifoaming agents, antiseptics, antifungal agents, coloring pigments, deodorants, fragrances and the like can be mentioned. Also, emulsions other than the aqueous emulsion (A), for example, conventionally known acrylic emulsions, polyvinyl acetate emulsions, ethylene-vinyl acetate copolymer emulsions, synthetic resin emulsions such as SBR latex, and various rubber latexes may be used in combination. Can do.

  The water-resistant emulsion composition of the present invention forms a film by evaporating and drying water. Even in the case of a film formed under mild drying conditions at about room temperature, sufficient water resistance is exhibited. However, when the film is subjected to heat treatment, the water resistance is drastically improved. Also, the film exhibits extremely excellent water resistance by making the pH of the composition acidic. Furthermore, even when the pH of the composition is adjusted using ammonia or the like, and the treatment is performed such that ammonia evaporates during drying to lower the pH of the composition, the film exhibits excellent water resistance.

  The water-resistant emulsion composition of the present invention is generally prepared by adding PAA (B) to an aqueous emulsion (A) as a solid or after making it into an aqueous solution. Moreover, the preparation of the composition may be either a batch method or a continuous method.

  The viscosity of the water-resistant emulsion composition of the present invention can be arbitrarily selected according to each application, but generally, as long as the viscosity measured using a B-type viscometer is in the range of 100 to 500,000 mPa · S, many It can be applied to any use.

  The water-resistant emulsion composition of the present invention is excellent in viscosity stability and water resistance, and is also excellent in terms of safety because it does not contain harmful components. It is preferably used for various adhesives, coating agents, binders for various paints, and the like, but is not limited thereto.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these Examples. In the following Examples and Comparative Examples, “parts” and “%” mean weight basis unless otherwise specified.

[Production of aqueous emulsion]
Production Example 1 of Aqueous Emulsion
In a 1 liter glass polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet, ion-exchanged water 350 g, PVA-1 (degree of polymerization 1750, vinyl alcohol (VA) unit 88.3 mol%) 29.6 g was charged and completely dissolved at 95 ° C. Next, this aqueous PVA solution was cooled, purged with nitrogen, charged with 37 g of vinyl acetate while stirring at 200 rpm, heated to 60 ° C., and then polymerization was initiated using a hydrogen peroxide / tartaric acid redox initiator. . From 15 minutes after the start of the polymerization, 333 g of vinyl acetate was continuously added over 3 hours to complete the polymerization. A polyvinyl acetate emulsion having a solid content concentration of 50.0% and a particle size of 0.9 μm was obtained. An aqueous emulsion-1 (EM-1) was obtained by adding and mixing 5 parts of dibutyl phthalate as a plasticizer with respect to 100 parts by weight of the solid content of the emulsion.

Production Example 2 of Aqueous Emulsion
In a 1 liter glass polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet, ion-exchanged water 350 g, PVA-2 (degree of polymerization 1100, vinyl alcohol unit 93.6 mol%, ethylene unit 29.6 g) (content 4.5 mol%) was charged and completely dissolved at 95 ° C. Next, this PVA aqueous solution was cooled, purged with nitrogen, charged with 36.6 g of vinyl acetate and 0.4 g of acrylic acid while stirring at 200 rpm, heated to 60 ° C., and then the hydrogen peroxide / tartaric acid redox was started. Polymerization was initiated using the agent. From 15 minutes after the start of the polymerization, a mixture of 329.7 g of vinyl acetate and 3.3 g of acrylic acid was continuously added over 3 hours to complete the polymerization. A vinyl acetate-acrylic acid copolymer emulsion having a solid content concentration of 50.1% and a particle size of 1.0 μm was obtained. An aqueous emulsion-2 (EM-2) was obtained by adding and mixing 5 parts of dibutyl phthalate as a plasticizer with respect to 100 parts by weight of the solid content of the emulsion.

Production Example 3 of Aqueous Emulsion
Aqueous emulsion production example 2 except that PVA-3 (degree of polymerization 1300, vinyl alcohol unit 93.1 mol%, acetoacetyl group 3.0 mol%) was used instead of PVA-2 in aqueous emulsion production example 2. In the same manner as above, a vinyl acetate-acrylic acid copolymer emulsion having a solid content concentration of 49.8% and a particle size of 0.9 μm was obtained. An aqueous emulsion-3 (EM-3) was obtained by adding and mixing 5 parts of dibutyl phthalate as a plasticizer with respect to 100 parts by weight of the solid content of the emulsion.

Production Example 4 of Aqueous Emulsion
In aqueous emulsion production example 2, PVA-4 (polymerization degree 400, vinyl alcohol unit 88.3 mol%, ethylene unit 9.0 mol%) was used in place of PVA-2, as in aqueous emulsion production example 2. Thus, a vinyl acetate-acrylic acid copolymer emulsion having a solid content concentration of 50.0% and a particle size of 0.8 μm was obtained. An aqueous emulsion-4 (EM-4) was obtained by adding and mixing 5 parts of dibutyl phthalate as a plasticizer with respect to 100 parts by weight of the solid content of the emulsion.

Production Example 5 of aqueous emulsion
In the production example 1 of the aqueous emulsion, a solid content concentration of 50 was obtained in the same manner as in the production example 1 of the aqueous emulsion, except that PVA-5 (polymerization degree 550, vinyl alcohol unit 84.5 mol%) was used instead of PVA-1. A polyvinyl acetate emulsion of 3% and a particle size of 1.2 μm was obtained. An aqueous emulsion-5 (EM-5) was obtained by adding and mixing 5 parts of dibutyl phthalate as a plasticizer with respect to 100 parts by weight of the solid content of the emulsion.

Production Example 6 of aqueous emulsion
10.8 g of PVA-6 (degree of polymerization 700, vinyl alcohol unit 88.7 mol%) was dissolved in 290 g of ion-exchanged water by heating and charged into a pressure-resistant autoclave equipped with a nitrogen inlet and a thermometer. After adjusting the pH to 4.0 with dilute sulfuric acid, 288 g of vinyl acetate was charged, and then the pressure of ethylene was increased to 42 kg / cm ² G (the charged amount of ethylene corresponds to 72 g). After raising the temperature to 60 ° C., polymerization was started using a hydrogen peroxide-Longalite redox initiator. After 2 hours, the polymerization was terminated when the residual vinyl acetate concentration reached 0.7%, and a vinyl acetate-ethylene copolymer emulsion (EM-6) having a solid content concentration of 53.3% and a particle size of 0.8 μm was obtained. Obtained.

Production Example 7 of aqueous emulsion
In a 1 liter glass polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen blowing port, ion-exchanged water 350 g, PVA-7 (polymerization degree 600, vinyl alcohol unit 92.5 mol%) 33.3 g Was completely dissolved at 95 ° C. Next, this PVA aqueous solution was cooled, purged with nitrogen, charged with 25.9 g of vinyl acetate and 10.4 g of N-butyl acrylate while stirring at 200 rpm, heated to 60 ° C., and then 10 g of 2% aqueous potassium persulfate solution. Was added to initiate the polymerization. 15 minutes after the start of the polymerization, a mixture of 233.1 g of vinyl acetate, 93.2 g of N-butyl acrylate and 7.4 g of N-isobutoxymethyl methacrylamide was continuously added over 4 hours to complete the polymerization. A vinyl acetate-butyl acrylate copolymer emulsion (EM-7) having a solid content concentration of 49.6% and a particle size of 0.8 μm was obtained.

Production Example 8 of Aqueous Emulsion
18 g of PVA-7 (degree of polymerization 600, vinyl alcohol unit 92.5 mol%) and 3.0 g of nonionic surfactant (Nonipol 200: manufactured by Sanyo Kasei) were dissolved in 290 g of ion-exchanged water by heating and dissolved in nitrogen. A pressure-resistant autoclave equipped with an inlet and a thermometer was charged. After adjusting to pH 4.0 with dilute sulfuric acid, charged with 120 g of styrene and 3.0 g of methacrylic acid, then charged with 177 g of butadiene from a pressure gauge, heated to 70 ° C., and injected with 10 g of 2% potassium persulfate aqueous solution. Polymerization was started. The internal pressure decreased from 4.8 kg / cm ² G with the progress of the polymerization, and after 15 hours, the polymerization was terminated when the internal pressure decreased to 0.4 kg / cm ² G. The obtained emulsion was adjusted to pH 6.0 with aqueous ammonia, and a styrene-butadiene copolymer emulsion (EM-8) having a solid content concentration of 49.5% and a particle size of 0.6 μm was obtained.

[Manufacture of PAA]
Production example 1 of PAA
A 2 liter reaction vessel equipped with a stirrer and a reflux condenser was charged with 90 g of acrylic acid, 10 g of N-2,2-dimethoxyethyl methacrylamide and 400 g of methanol, and the contents were heated to 65 ° C. Next, after bubbling with nitrogen for 30 minutes and sufficiently degassing, 1.0 g of 2,2′-azobisisobutyronitrile (AIBN) was added as an initiator. Three hours after the addition of the initiator, an additional 0.5 g of the initiator was further added and driven for 1 hour. Thereafter, 500 g of methanol was added and cooled to stop the polymerization. When this methanol solution was dried under reduced pressure at 60 ° C., 90 g of a PAA copolymer (PAA-1) as a white solid was obtained. When PAA-1 was dissolved in D ₂ O and ¹ H-NMR was measured, peaks suggesting the presence of polyacrylic acid were confirmed around σ = 1.5 ppm and σ = 2.1 ppm, and σ = 3. A peak indicating the presence of a methoxy group (—OCH ₃ ) of dimethyl acetal was observed near 0 to 3.3 ppm. Moreover, the modification amount of the acetal calculated from this NMR spectrum was 5.5 mol%. In addition, the weight average molecular weight (Mw) of PAA-1 is GPC [apparatus: 150C-2 (manufactured by Waters), column: GMPWXL (manufactured by Tosoh), mobile phase: 0.2M phosphoric acid Buffer, sample: PEO / Mw was 420,000 as measured using PEG].

PAA production examples 2 to 4
Various PAA copolymers (PAA-2 to PAA-4) were prepared in the same manner as PAA1 except that the types and amounts of the acrylic acid and acetal-containing ethylenically unsaturated monomers were changed to those shown in Table 2. ) Was manufactured.

  As an unmodified PAA polymer, Aldrich Chemical Company, Inc. Polyacrylic acid manufactured (Mw = 2000) was used (PAA-5).

Example 1
10 parts by weight of PAA-1 was added to 100 parts by weight of the solid content of EM-1, and the temperature was raised to 80 ° C. to dissolve PAA-1, thereby preparing a water-resistant emulsion composition. The following evaluation was performed using this water-resistant emulsion composition. The results are shown in Table 3.

[Evaluation of water-resistant emulsion composition]
(1) Water resistance of film The water-resistant emulsion composition was cast on a PET film at 20 ° C. and 65% RH and dried for 7 days to obtain a dry film of 500 μm. When this film is punched to a diameter of 2.5 cm and immersed in water at 20 ° C. for 24 hours as a sample, the water absorption rate of the film (%) [{(weight after immersion−weight before immersion) / before immersion) Weight} × 100].
(2) Water-resistant adhesive strength (boil-resistant adhesive strength)
Vertical 2.5 cm, horizontal 2.5 cm, a pair of hemlock material thickness 1.0cm (the straight grain) a test piece, the amount of coating was coated a water resistant emulsion composition such that 150 g / m ² to this paste In total, pressing was performed at a load of 7 kg / m ² for 16 hours. Then, the pressure was released, and after curing for 5 days at 20 ° C. and 65% RH, immersed in boiling water for 4 hours, dried at 60 ° C. for 20 hours, further immersed in boiling water for 4 hours, and kept wet. The compression shear strength was measured.
(3) Viscosity stability (pot life)
When the water-resistant emulsion composition was left at 30 ° C., the change in viscosity after 30 days was observed.

Examples 2-3 and Comparative Examples 1-2
A water-resistant emulsion composition was prepared in the same manner as in Example 1 except that the amount of PAA-1 added to 100 parts by weight of the solid content of EM-1 was changed. Evaluation was performed in the same manner as in Example 1 using these water-resistant emulsion compositions. The results are shown in Table 3.

Comparative Example 3
Evaluation was performed in the same manner as in Example 1 using only EM-1. The results are shown in Table 3.

Examples 4-5, Comparative Examples 4-5
In Example 1, a water-resistant emulsion composition was prepared in the same manner as in Example 1 except that PAA-2 to PAA-5 were used instead of PAA-1. Evaluation was performed in the same manner as in Example 1 using these water-resistant emulsion compositions. The results are shown in Table 3.

Examples 6-11, Comparative Example 6
In Example 1, a water-resistant emulsion composition was prepared in the same manner as in Example 1 except that EM-2 to EM-8 were used instead of EM-1. Evaluation was performed in the same manner as in Example 1 using these water-resistant emulsion compositions. The results are shown in Table 3.

Examples 12-13
The same procedure as in Example 1 was carried out except that the water-resistant emulsion composition was prepared by adding 1 wt% of aluminum nitrate and ammonium zirconium carbonate per 100 parts by weight of the solid content of the water-resistant emulsion composition obtained in Example 6. . Evaluation was performed in the same manner as in Example 1 using these water-resistant emulsion compositions. The results are shown in Table 3.

  As can be seen from the results in Table 3, the water-resistant emulsion composition of the present invention satisfies both the viscosity stability and water resistance at a high level at the same time. Therefore, in addition to excellent workability, it is excellent in durability around water and under high humidity. Moreover, the water-resistant emulsion composition of the present invention is excellent in safety because it does not contain harmful components.

  Since the water-resistant emulsion composition of the present invention is excellent in viscosity stability and water resistance, and also in terms of safety, it is various for paperwork, woodwork, and film (PVA film, triacetate film, etc.). It can be suitably used for adhesives, coating agents, binders for various paints, and the like.

Claims (5)

  A polyvinyl alcohol polymer (a) having a vinyl alcohol unit of 85 mol% or more is used as a dispersant, and it comprises at least one monomer unit selected from ethylenically unsaturated monomers and diene unsaturated monomers. Aqueous emulsion (A) having fine polymer particles (b) as a dispersoid, and the acetal group-containing ethylenically unsaturated monomer obtained by copolymerization of acrylic acid and an acetal group-containing ethylenically unsaturated monomer The polyacrylic acid copolymer (B) containing 5 to 40 mol% of the unit derived from is contained, and the ratio (A) :( B) of (A) and (B) is 100: 1 in terms of solid content by weight. Water resistant emulsion composition that is ~ 100: 20. The water-resistant emulsion composition according to claim 1, wherein the acetal group-containing ethylenically unsaturated monomer is represented by the formula (1).

(Wherein R1 represents a hydrogen atom or —COOM, wherein M represents a hydrogen atom, an alkali metal or an ammonium group; R2 represents a hydrogen atom, a methyl group or —CH ₂ —COOM, where M represents As defined above, R 3 and R 4 are the same or different and each is a saturated alkyl group having 1 to 4 carbon atoms, X is —CO—, —CO—O— or —CO—NR 5, wherein R 5 is A hydrogen atom or a C1-C4 saturated alkyl group is meant, and n is an integer of 1-8.)   The water-resistant emulsion composition according to claim 1, further comprising a water-soluble polyvalent metal salt.   The water-resistant emulsion composition according to any one of claims 1 to 3, wherein the polyvinyl alcohol polymer (a) is an ethylene-modified polyvinyl alcohol polymer containing 2 to 8 mol% of an ethylene-derived unit.   The water-resistant emulsion composition according to any one of claims 1 to 4, wherein the polyvinyl alcohol polymer (a) is an acetoacetyl-modified polyvinyl alcohol polymer.