JPH0881664A - Adhesive - Google Patents

Abstract

PURPOSE: To obtain an adhesive consisting mainly of an aqueous emulsion comprising a specific dispersant and a specified dispersoid, excellent in water- resistant adhesiveness, low storage stability and fast coatability, and suitable as an adhesive for paper. CONSTITUTION: This adhesive consists mainly of an aqueous emulsion comprising (A) a modified PVA containing <=4C α-olefin units in an amount of 1-10mol.% as a dispersing agent and (B) a (co)polymer of one or more monomers selected from among ethylenic unsaturated monomers as a dispersoid. For example, the saponification product of a copolymer of a vinylic ester such as vinyl acetate with an α-olefin such as ethylene wherein the degree of saponification and the degree of polymerization of the saponification product are >=95% and 300-2000, respectively, is preferably used as the component A in an amount of 2-3 pts.wt. per 100 pts.wt. of the component B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive, and more specifically, as an adhesive for paper, an adhesive for woodworking, an adhesive for plastics, etc., which is excellent in water-resistant adhesiveness, stability at low temperature leaving, and high-speed coating property. It relates to a suitable aqueous emulsion type adhesive.

[0002]

2. Description of the Related Art Conventionally, a paper adhesive for adhering a paper to a base material such as paper, aluminum foil, or plastic film,
As an adhesive for woodworking for adhering a base material such as wood, paper, plastic, cloth and the like, or an adhesive for plastics for adhering a base material for plastic, wood, paper, cloth etc. and the plastic, Aqueous emulsions produced using polyvinyl alcohol (hereinafter abbreviated as PVA) as a protective colloid are widely used. Such an aqueous emulsion is generally high in viscosity and has a viscosity close to Newtonian flow, so that it is excellent in workability and mechanical suitability and has a high initial adhesive force,
It has been used as an adhesive for various purposes. However, the aqueous emulsion has drawbacks such as poor water resistance, large temperature dependence of emulsion viscosity, and lack of high-speed coating property, and these properties were used for emulsion polymerization. It is known that it depends largely on the dispersant.

That is, PV as a dispersant for emulsion polymerization
A is a so-called "completely saponified PVA" having a saponification degree of about 98 mol% and "partial saponification P" having a saponification degree of about 88 mol%.
When the former is used, the water resistance and the high-speed coating property are relatively good, but the emulsion viscosity increases remarkably at low temperature and gelation easily occurs. On the other hand, the latter PVA is used. In such a case, although the viscosity increase and gelation tendency of the emulsion at a low temperature are improved, the water-resistant adhesive strength is low and there is a problem such as splattering at the time of high-speed coating. for,
Both PVA's are used in combination, and PVA's having an intermediate saponification degree are used, but the water resistance, the high-speed coating property, and the small temperature dependence of the emulsion viscosity have not been sufficiently satisfied. In addition, in order to improve the water resistance of the film, urea resin and various crosslinking agents have been added to the emulsion using partially saponified PVA, but the water resistance is improved to some extent, but the viscosity increases when used. Workability deteriorates, and these methods have not obtained sufficiently satisfactory results.

[0004]

SUMMARY OF THE INVENTION Under the circumstances, the present invention provides a water resistant adhesive strength and stability at low temperature without impairing the features (workability, initial adhesive strength, etc.) of the PVA protective colloidal aqueous emulsion. And high speed coating,
It is an object of the present invention to provide an aqueous emulsion type adhesive suitable as an adhesive for paper, an adhesive for woodworking, an adhesive for plastics and the like.

[0005]

As a result of intensive studies to develop an adhesive having the above-mentioned preferable properties, the present inventors have found that the dispersant contains 1 to 10 α-olefin units having 4 or less carbon atoms. An adhesive mainly composed of an aqueous emulsion which is a modified polyvinyl alcohol containing mol% and whose dispersoid is a (co) polymer of one or more monomers selected from ethylenically unsaturated monomers. Heading, completes the present invention.

The modified PVA containing 1 to 10 mol% of an α-olefin unit having 4 or less carbon atoms, which is used as a dispersant for the aqueous emulsion type adhesive of the present invention, comprises a copolymer of vinyl ester and α-olefin. It can be obtained by saponification. Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, etc., and vinyl acetate is economically preferable.
The α-olefin of the present invention has a carbon number of 4 or less, and examples thereof include ethylene, propylene, n-butene, and isobutene, and ethylene is preferable from the viewpoint of the water-resistant adhesive strength of the resulting aqueous emulsion adhesive. The content of α-olefin is 1 to 10 mol%, preferably 2 to 8
Must be mol%. When the content of α-olefin is less than 1 mol%, the above-mentioned remarkable effect cannot be obtained, and when it exceeds 10 mol%, the water solubility is decreased,
A stable aqueous emulsion cannot be obtained, and the above effects cannot be obtained.

The dispersant may be a copolymer of an ethylenically unsaturated monomer which is copolymerizable within a range that does not impair the effects of the present invention. Examples of such ethylenically unsaturated monomers include acrylic acid, methacrylic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, Trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, N-vinyl pyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride. , Vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinyl sulfonate, sodium allyl sulfonate and the like. Further, it is obtained by copolymerizing a vinyl ester monomer such as vinyl acetate with an α-olefin having 4 or less carbon atoms in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid, and saponifying it. A terminal modified product can also be used.

1 to 1 of an α-olefin having 4 or less carbon atoms used as a dispersant for the aqueous emulsion type adhesive of the present invention.
The modified PVA containing 0 mol% has a saponification degree of preferably 50 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, although it depends on the α-olefin content. The degree of polymerization of the PVA is preferably 100 to 8000, more preferably 300 to 2000.

There are various types of (co) polymers of ethylenically unsaturated monomers which are dispersoids in the aqueous emulsion of the adhesive of the present invention. Preferred examples of unsaturated monomers include olefins such as ethylene, propylene and isobutylene, vinyl chloride, vinyl fluoride, halogenated olefins such as vinylidene chloride and vinylidene fluoride, vinyl formate, vinyl acetate, vinyl propionate and versatic. Vinyl esters such as vinyl acrylate, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, acrylic acid esters such as 2-hydroxyethyl acrylate, methyl methacrylate , Ethyl methacrylate, methacrylic acid Cyl, 2-ethylhexyl methacrylate, dodecyl methacrylate, methacrylic acid esters such as 2-hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and quaternary products thereof, and further acrylamide, methacrylamide, Acrylamide monomers such as N-methylolacrylamide, N, N-dimethylacrylamide, acrylamido-2-methylpropanesulfonic acid and its sodium salt, styrene, α-methylstyrene, p-styrenesulfonic acid and sodium, potassium salts, etc. Styrene monomer, other N-vinylpyrrolidone, etc., butadiene, isoprene,
Examples thereof include diene-based monomers such as chloroprene, which may be used alone or in admixture of two or more. Among the above-mentioned ethylenically unsaturated monomers, vinyl ester, (meth) acrylic acid ester, styrene and diene-based monomers are preferable, and particularly vinyl ester, a combination of ethylene and vinyl ester, and vinyl ester and (meth) acryl. The combined use of acid esters is preferred.

The aqueous emulsion in the adhesive of the present invention uses the above-mentioned aqueous solution of modified PVA having an α-olefin unit having 4 or less carbon atoms as a dispersant, and in the presence of a polymerization initiator, the above-mentioned ethylenic unsaturated. It is obtained by adding a monomer temporarily or continuously and emulsion-polymerizing the ethylenically unsaturated monomer. An emulsion polymerization method in which an ethylenically unsaturated monomer is previously emulsified with a modified PVA aqueous solution having an α-olefin unit having 4 or less carbon atoms and continuously added to a polymerization reaction system can also be employed. The amount of the α-olefin modified PVA used is not particularly limited, but is preferably 1 to 30 parts by weight, more preferably 2 to 2 parts by weight with respect to 100 parts by weight of the polymer of the ethylenically unsaturated monomer.
It is in the range of 0 parts by weight. If the amount used is less than 1 part by weight or more than 30 parts by weight, the polymerization stability may be lowered, or the initial adhesive strength or the water resistant adhesive strength may be lowered.

As the polymerization initiator, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide,
t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, benzoyl peroxide, ammonium peroxoborate, azobisisobutyronitrile, 2,2-azobis (2-amidinopropane) dihydrochloride, etc. Known polymerization initiators can be used. These polymerization initiators may be used alone, or by combining with a reducing agent such as sodium bisulfite, tartaric acid, citric acid, glucose, L-ascorbic acid, sodium formaldehyde sulfoxylate, and iron ion, redox It may be used in the system.
The amount and method of use of the polymerization initiator may be those conventionally known.

The following conventionally known surfactants may be added to the aqueous emulsion of the present invention before the initiation of emulsion polymerization, during emulsion polymerization or after emulsion polymerization. As the surfactant, potassium oleate, potassium castor oil, semi-hardened tallow fatty acid sodium, semi-hardened tallow fatty acid potassium, sodium lauryl sulfate, triethanolamine lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate. , Sodium alkyl diphenyl ether disulfonate, potassium alkyl phosphate, sodium salt of β-naphthalene sulfonic acid formalin condensate, sodium salt of aromatic sulfonic acid formalin condensate, sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene alkylphenyl ether sulfate Sodium, sodium bistridecyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium dihexyl sulfosuccinate Beam, sodium dicyclohexyl sulfosuccinate,
Sodium diamyl sulfosuccinate, sodium diisobutyl sulfosuccinate, sodium isodecyl sulfosuccinate, disodium sulfosuccinate ethoxylated alcohol half ester, sulfosuccinate disodium ethoxylated nonylphenyl half ester, N- (1,2-dicarboxyethyl)- Anionic surfactants such as tetrasodium N-octadecylsulfosuccinamide, disodium N-octadecylsulfosuccinamide, sodium diisopropylnaphthalenesulfonate, sodium tripolyphosphate, sodium hexametaphosphate; polyoxyethylene lauryl ether, polyoxyethylene cetyl ether , Polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl ether Nonyl ether, polyoxyethylene nonylphenyl ether, oxyethylene-oxypropylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid monoglyceride, polyethylene glycol fatty acid ester, polyoxyethylene lauryl amine, polyoxyethylene stearyl amine Cationic surfactants; cationic surfactants such as stearylamine acetate, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, alkylaminganidinium polyoxyethanol, alkylbenzyldimethylammonium chloride; laurylbetaine, stearylbetaine , Lauryl dimethy LATEMUL introducing the double bond in addition the above surfactants S-; amine oxide, amphoteric surfactants such as lauryl carboxymethyl hydroxyethyl imidazolinium betaine
180, S-120 (above, Kao Corporation make), ADEKA rear soap NE-10, ADEKA rear soap NE-20,
ADEKA Rear Soap NE-30, ADEKA Rear Soap SE-
10N (above, Asahi Denka Co., Ltd.), Eleminor JS
-2 (manufactured by Sanyo Kasei Co., Ltd.), Aqualon RN-20,
Reactive surfactants such as Aqualon HS-10 (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) can be mentioned. When the surfactant is added, it is added in an amount of 0 to 10 parts by weight (preferably 0.1 to 10 parts by weight, more preferably 0.1 to 100 parts by weight) per 100 parts by weight of the monomer (polymer of dispersoid). 5 to 5 parts by weight, and even more preferably 1 to 5 parts by weight).

The following conventionally known plasticizers or film-forming aids may be added to the aqueous emulsion of the present invention during or after the emulsion polymerization. As a plasticizer or a film-forming aid, dimethyl phthalate, diethyl phthalate, diamyl phthalate, dibutyl phthalate (DB
P), tributyl acetyl citrate, diisobutyl adipate, dibutyl sebacate, dimethyl glycol adipate, diethyl glycol adipate, dibutyl glycol adipate, dimethyl glycol sebate, diethyl glycol sebate, dimethyl glycol phthalate, diethyl glycol phthalate, dibutyl glycol phthalate, Tricresyl phosphate, dioctyl phthalate, texanol, polyethylene glycol monophenyl ether, polypropylene glycol monophenyl ether, benzyl alcohol, butyl carbitol acetate, butyl carbitol, 3-methyl-3-methoxybutanol, ethylene glycol, acetylene glycol butyl cellosolve , Ethylene cellosolve, bife chloride Lumpur, and the like. When the plasticizer or the film-forming auxiliary is added, it is added in an amount of 0 to 200 parts by weight (preferably 1 to 100 parts by weight, more preferably 100 parts by weight of the monomer (dispersoid polymer)). 5-2
0 parts by weight).

After the emulsion polymerization, the following well-known fillers, fillers or pigments may be added to the aqueous emulsion of the present invention. As the filler, filler or pigment, calcium carbonate, kaolin clay, wax clay, talc, titanium oxide, iron oxide, pulp, various resin powders, mica, sericite, bentonite, asbestos, calcium silicate, aluminum silicate, Examples thereof include diatomaceous earth, silica, anhydrous silicic acid, hydrous silicic acid, magnesium carbonate, aluminum hydroxide, barium sulfate, calcium sulfate, and carbon black. When a filler, a filler or a pigment is added, it is added in an amount of 1 to 200 parts by weight (preferably 20 to 150 parts by weight, more preferably 50 to 150 parts by weight) with respect to 100 parts by weight of the dispersoid polymer.
Parts by weight).

The following conventionally known extenders may be added to the aqueous emulsion of the present invention after emulsion polymerization.
As the filler, casein, glue, gelatin, gluten, soybean protein, ammonium alginate, potassium alginate, sodium alginate, arabic gum, tragacanth gum, karaya gum, guar gum, locust bean gum, Irish moss, soybean lecithin, pectic acid, starch, agar. , Bentonite clay, ammonium polyacrylate, sodium polyacrylate, polyacrylic acid, ammonium polymethacrylate, polyvinyl alcohol, modified poly (vinyl methyl ether / maleic anhydride), polyvinylpyrrolidone, polyacrylamide,
Examples thereof include polyethylene oxide, carboxylated methyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, cellulose xanthate, carboxylated starch, ammonium oleate, and sodium silicate. When the filler is added, it is added in an amount of 0.1 to 100 parts by weight (preferably 0.5 to 50 parts by weight) based on 100 parts by weight of the dispersoid polymer.
Parts by weight, more preferably 1 to 20 parts by weight).

The aqueous emulsion used in the present invention is
The aqueous emulsion obtained by the above method may be used as it is, but if necessary, various conventionally known emulsions can be added within a range that does not impair the effects of the present invention.

The adhesive of the present invention basically comprises the above-mentioned aqueous emulsion, but in order to adjust its drying property, setting property, viscosity, film-forming property, etc., if necessary, toluene, perkrene, diester or the like is used. Various organic solvents such as chlorobenzene and trichlorobenzene, urea / formalin resin, urea /
Thermosetting resins generally used as adhesives, such as melamine / follymarin resins and phenol / hollymarin resins, can be appropriately used. Furthermore, various additives such as reaction promoters such as boric acid and aluminum sulfate, defoaming agents, dispersants, antifreezing agents, antiseptics, and rust inhibitors may be appropriately added to the adhesive of the present invention. it can.

[0018]

The present invention will be described in more detail with reference to Examples and Comparative Examples. In the following Examples and Comparative Examples, "part" and "%" mean weight basis unless otherwise specified. In addition, the stability of the obtained adhesive at low temperature, high-speed coating property (dependence of viscosity on shear rate), performance as an adhesive for paper, performance as an adhesive for woodworking and performance as an adhesive for plastics The evaluation was performed as follows.

(1) Low temperature storage stability test The emulsion was placed in a 100 ml glass sample tube and left at 5 ° C for 30 days, and the viscosity ratio before and after standing at 5 ° C was determined. The measurement was performed at 30 ° C. using a B-type viscometer (rotation speed 60 rpm). Thickening index = (viscosity after leaving at 5 ° C. for 30 days) / (viscosity before leaving at 5 ° C.)

(2) High-speed coating property The viscosity at 30 ° C. was measured with a B type viscometer by changing the rotation speed, and the shear rate dependence of the viscosity was determined by the following formula. Shear rate dependence of viscosity =-(Log η _r1 −Log η _r2 ) /
(Log60-Log6) (η _r1 : viscosity at 60 rpm, η _r2 : viscosity at 6 rpm)

(3) Performance as an Adhesive for Paper 20 g / adhesive of kraft paper with a bar coater
Apply m ² and immediately bond the same type of kraft paper,
It was lightly pressed and adhered with a hand roller, and aged at 20 ° C. and 65% relative humidity (RH) for 24 hours to obtain a test piece. -Water resistance test (boiling resistance) The above test piece is cut into a width of 25 mm, the uncoated portion is opened vertically and the upper portion is fixed, and a weight of 10 g is attached to the stock. It was put in boiling water for 10 minutes, and the peeled length of the adhesive part was measured.

(4) Performance as an adhesive for woodworking Wood / wood (birch material) adhesive strength test A test piece was prepared under the following conditions, and the adhesive strength was measured. [Adhesion conditions] Substrate: Hippo / Hippo (Heat), Water content 8% Application amount: 150 g / m ² (Double-side application) Deposition time: 1 minute Clamping condition: 20 ° C, 24 hours, pressure 10 kg / cm ² [Measurement conditions] Measure the compression shear adhesive strength in accordance with JIS K-6852 Normal strength: measured at 20 ° C for 7 days, and then as-is Measured Water resistance strength: 20 ° C, cured for 7 days, test specimens are kept at 20 ° C water Measured in the wet state after being immersed in water for 3 hours. Warm water resistance strength: After curing for 7 days at 20 ° C, the test piece was immersed in warm water at 60 ° C for 3 hours, cooled in water at 20 ° C, and kept wet. Measured in

(5) Performance as an Adhesive for Plastics Paper / Polypropylene (PP) Film Adhesion Test Specimens were prepared under the following conditions, and the adhesive strength was measured. [Adhesion conditions] Adhering material: Kraft paper / stretched polypropylene (OPP) film (20 μm) Application amount: 30 g / m ² Deposition time: 0 minutes Clamping condition: Lightly clamping with a rubber hand roller [Measurement conditions] Normal state: 20 After curing for 7 days at ℃, peeled by hand, the peeled state was observed. Water resistance: After curing at 20 ° C. for 7 days, it was immersed in 20 ° C. water for 24 hours, and then peeled by hand, and the peeled state was observed.

Example 1 A 1-liter glass polymerization container equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet was charged with 400 parts of ion-exchanged water.
g, ethylene-modified PVA (polymerization degree 1400, saponification degree 9
8.5 mol%, ethylene 4.5 mol% modified) 40 g
Was charged and completely dissolved at 95 ° C. Next, after cooling this PVA aqueous solution and replacing with nitrogen, 40 g of vinyl acetate was charged while stirring at 140 rpm, the temperature was raised to 60 ° C., and then polymerization was initiated in the presence of a hydrogen peroxide / tartaric acid redox initiator system. . 15 minutes after the initiation of the polymerization, 360 g of vinyl acetate was continuously added over 3 hours to complete the polymerization.
Solid content concentration 50.4%, viscosity 4500 mPa.s. A stable polyvinyl acetate emulsion of s was obtained. An adhesive was prepared by adding and mixing 10 parts of dibutyl phthalate to 100 parts by weight of the solid content of this emulsion. This adhesive was evaluated for stability at low temperature, high-speed coating property, performance as an adhesive for paper, performance as an adhesive for woodworking, and performance as a plastic adhesive. The results are shown in Tables 1-5.

Comparative Example 1 Instead of the ethylene-modified PVA used in Example 1, unmodified PVA (polymerization degree 1400, saponification degree 98.5 m) was used.
ol%) in the same manner as in Example 1 except that 40 g is used,
Solid content concentration 50.3%, viscosity 4000 mPa.s. A stable polyvinyl acetate emulsion of s was obtained. An adhesive was prepared by adding and mixing 10 parts of dibutyl phthalate to 100 parts of the solid content of this emulsion. This adhesive was used and evaluated in the same manner as in Example 1.

Comparative Example 2 Instead of the ethylene-modified PVA used in Example 1, unmodified PVA (polymerization degree 1400, saponification degree 88.2 m) was used.
ol%) in the same manner as in Example 1 except that 40 g is used,
Solid content concentration 50.2%, viscosity 13000 mPa.s. A stable polyvinyl acetate emulsion of s was obtained. An adhesive was prepared by adding and mixing 10 parts of dibutyl phthalate to 100 parts by weight of the solid content of this emulsion. This adhesive was used and evaluated in the same manner as in Example 1.

Comparative Example 3 Instead of the ethylene-modified PVA used in Example 1, ethylene-modified PVA (polymerization degree 1400, saponification degree 9) was used.
Emulsion polymerization of vinyl acetate was carried out in the same manner as in Example 1 except that 40 g of (8.5 mol%, modified with 11 mol% of ethylene) was used. This ethylene-modified PVA was not completely dissolved in water, and gelled and solidified during the emulsion polymerization.

Comparative Example 4 Instead of the ethylene-modified PVA used in Example 1, ethylene-modified PVA (polymerization degree 1400, saponification degree 9
8.5 mol%, ethylene 0.5 mol% modified) 40 g
The solid content concentration is 5 in the same manner as in Example 1 except that
0.3%, viscosity 4200 mPa.s. A stable polyvinyl acetate emulsion of s was obtained. Solid content of this emulsion 1
An adhesive was prepared by adding and mixing 10 parts of dibutyl phthalate to 100 parts by weight. This adhesive was used and evaluated in the same manner as in Example 1.

Example 2 Ethylene-modified PVA (polymerization degree 1750, saponification degree 98.7)
21 g of (mol%, modified with 3.0 mol% of ethylene) was dissolved in 290 g of ion-exchanged water by heating, and the solution was placed in a pressure-resistant autoclave equipped with a nitrogen inlet and a thermometer. After adjusting the pH to 4 with dilute sulfuric acid, 300 g of vinyl acetate was charged, and then the pressure of ethylene was increased to 45 kg / cm ² G (the ethylene copolymerization amount corresponds to 60 g). After the temperature was raised to 60 ° C., polymerization was initiated with hydrogen peroxide / Rongalite redox initiator. After 2 hours, the polymerization was terminated when the residual vinyl acetate concentration reached 0.6%. Solid content concentration 52.6%, viscosity 6300 mPa.s. A stable poly (ethylene-vinyl acetate) copolymer emulsion of s was obtained. This emulsion was evaluated as an adhesive in the same manner as in Example 1.

Comparative Example 5 Instead of the ethylene-modified PVA used in Example 2, unmodified PVA (polymerization degree 1700, saponification degree 98.6 m) was used.
ol%) in the same manner as in Example 2 except that 21 g is used,
Solid content concentration 52.4%, viscosity 6000 mPa.s. A stable polyvinyl acetate emulsion of s was obtained. This was used as an adhesive and evaluated in the same manner as in Example 1.

Example 3 A 1 liter glass-made polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen blowing port was charged with ion-exchanged water 400.
g, ethylene-modified PVA (polymerization degree 1000, saponification degree 9
5.0 mol%, ethylene 6.0 mol% modified) 36 g
Was charged and completely dissolved at 95 ° C. Next, after cooling this PVA aqueous solution and purging with nitrogen, while stirring at 140 rpm, vinyl acetate 32 and n-butyl acrylate 8 g were charged, the temperature was raised to 70 ° C., and then polymerization was started using potassium persulfate as an initiator. did. After heat generation was confirmed by initiation of polymerization, 288 g of vinyl acetate and 72 g of butyl acrylate were continuously added over 3 hours to complete the polymerization. Solid content concentration 50.0%, viscosity 2000 mPa.s. s
A stable poly (vinyl acetate-n-butyl acrylate) copolymer emulsion was obtained. This emulsion was evaluated as an adhesive in the same manner as in Example 1.

Comparative Example 6 Instead of the ethylene-modified PVA used in Example 3, unmodified PVA (polymerization degree 1000, saponification degree 95.0 m
ol%) except that 36 g is used,
Solid content concentration 50.2%, viscosity 2200 mPa.s. A stable polyvinyl acetate emulsion of s was obtained. This was used as an adhesive and evaluated in the same manner as in Example 1.

[0033]

[Table 1]

* 1: Polymerization degree 1400, saponification degree 98.5 mo
1%, ethylene 4.5 mol% modified * 2: degree of polymerization 1400, degree of saponification 98.5 mol% * 3: degree of polymerization 1400, degree of saponification 88.2 mol% * 4: degree of polymerization 1400, degree of saponification 98.5 mol%, ethylene 11.0 mol% modification * 5: Polymerization degree 1400, saponification degree 98.5 mol%, ethylene 0.5 mol% modification * 6: Polymerization degree 1750, saponification degree 98.7 mol%, ethylene 3.0 mol% modification * 7: Polymerization degree 1700, saponification degree 98.6 mol% * 8: degree of polymerization 1000, saponification degree 95.0 mol%, ethylene 6.0 mol% modification * 9: degree of polymerization 1000, saponification degree 95.0 mol%

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

The adhesive of the present invention is preferably used for paper adhesives, woodworking adhesives, plastics adhesives, etc., which are required to have water-resistant adhesiveness, low-temperature storage stability and high-speed coating property.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Daisuke Miyake 1-1239 Umeda, Kita-ku, Osaka City, Osaka Prefecture Kuraray Co., Ltd.

Claims (4)

[Claims] 1. A dispersant is a modified polyvinyl alcohol containing 1 to 10 mol% of an α-olefin unit having 4 or less carbon atoms, and the dispersoid is one or more selected from ethylenically unsaturated monomers. An adhesive whose main component is an aqueous emulsion which is a (co) polymer of monomers. 2. An adhesive for paper comprising the adhesive according to claim 1. 3. An adhesive for woodworking, which comprises the adhesive according to claim 1. 4. An adhesive for plastics comprising the adhesive according to claim 1.