JPH1135912A - Preparation of adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition which not only is excellent in mechanical stability and storage stability, but also has good adhesiveness, resistance to water and thermal stability, by employing a preparation method comprising carrying out the addition with mixing of an anionic urethane resin emulsion after adjusting the pH of a liquid mixture of a vinyl acetate resin emulsion and a calcium carbonate filler. SOLUTION: A vinyl acetate resin emulsion is obtained by the emulsion polymerization of monomers comprising a vinyl acetate monomer in the presence of a polymerization catalyst, using poly(vinyl alcohol) (PVA) as a protective colloid. It is preferred that the poly(vinyl alcohol) has an average polymerization degree of 500 to 5,000 and a saponification degree of 70 mole % or more. A commercially available calcium carbonate ia usable. The reaction is carried out at a pH of 6 to 9. An anionic urethane resin emulsion is obtained by reacting a polyol compound, a polyisocyanate compound and a functional compound having one or more active hydrogen (for example, ethylenediamine) and an acid group (for example, 3,4-diaminobutanesulfonic acid) in the molecule thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an emulsion type adhesive composition.

[0002]

2. Description of the Related Art Conventionally, a hard or semi-hard plastic material sheet, a veneer obtained by processing wood into a sheet shape,
Surface decorative sheets such as decorative paper with various decorative prints applied
Wood material such as Rawan plywood, medium density fiberboard (MDF), particle board, cement board, gypsum board, AL
BACKGROUND ART A so-called surface decorative plate adhered to the surface of a base material such as an inorganic material such as C and imparted with design properties is widely used as a building member, a furniture member, and the like.

[0003] The adhesion between the surface decorative sheet and the substrate is as follows.
BACKGROUND ART Adhesive compositions containing a vinyl acetate resin emulsion as a main component, such as a vinyl acetate resin emulsion, an ethylene-vinyl acetate copolymer emulsion, and an acrylate-vinyl acetate copolymer emulsion, are widely used.

In order to improve the adhesiveness and heat resistance of the adhesive composition containing the vinyl acetate resin emulsion as a main component to a hydrophobic adherend, for example, Japanese Patent Publication No.
No. 26072 discloses that “ethylene is contained in a resin by 10 to 2 times.
An emulsion of a vinyl acetate-ethylene copolymer containing 5% by weight, and a vinyl chloride-vinyl acetate-ethylene copolymer containing 20 to 70% by weight of vinyl chloride and further containing 10 to 25% by weight of ethylene in a resin Or an adhesive composition comprising a modified emulsion thereof and an aromatic or aliphatic isocyanate-based polyester-type water-soluble or water-dispersible urethane resin ".

[0005] However, since the pH of the vinyl acetate resin emulsion is usually on the acidic side, when a neutral or basic anionic urethane resin emulsion is blended as in the adhesive composition proposed in the above, First, a method is generally employed in which a vinyl acetate resin emulsion is neutralized with an aqueous solution of a basic salt such as aqueous ammonia or caustic soda to increase the pH, and then an anionic urethane resin emulsion is blended. .

[0006] As described above, by adopting a method in which the pH of the vinyl acetate resin emulsion is adjusted to be higher and then the anionic urethane resin emulsion is blended, remarkable thickening and coagulation due to ionic shock at the time of mixing the two are achieved. Can be prevented, and the resulting adhesive composition can be improved in mechanical stability such as roll coatability and storage stability such as viscosity stability with time.

However, when ammonia water is used to adjust the pH of the vinyl acetate resin emulsion, the ammonia water is volatile and gradually evaporates during storage.
There is a problem that the pH of the adhesive composition decreases with time, and the mechanical stability and storage stability also decrease.

[0008] The pH of the vinyl acetate resin emulsion
When an aqueous solution of a basic salt such as caustic soda is used for the adjustment, although the pH does not decrease over time as in the case of aqueous ammonia, the basic salt remains in the dried film of the adhesive composition. Therefore, there is a problem that the water resistance is reduced with time.

[0009]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and does not cause a remarkable increase in viscosity or agglomeration at the time of production and is excellent in mechanical stability and storage stability. Another object of the present invention is to provide a method for producing an emulsion-type adhesive composition having excellent adhesiveness, water resistance, heat resistance, and the like.

[0010]

According to the present invention, there is provided a method for producing an adhesive composition comprising the steps of: adding a calcium carbonate-based filler to a vinyl acetate-based resin emulsion; mixing the mixture;
After adjusting the pH to 6 to 9, an anionic urethane resin emulsion is added and mixed.

The vinyl acetate resin emulsion used in the production method of the present invention is not particularly limited. For example, polyvinyl alcohol (hereinafter referred to as “PVA”)
As a protective colloid.
It is obtained by emulsion (co) polymerization of a vinyl acetate monomer alone or a vinyl acetate monomer and a monomer copolymerizable with the vinyl acetate monomer in the presence of a polymerization catalyst. The term “emulsion (co) polymerization” used herein means “emulsion polymerization” or “emulsion copolymerization”.

The polymerizable monomer copolymerizable with the vinyl acetate monomer is not particularly limited. Examples thereof include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate. ) Acrylate, 2-ethylhexyl (meth) acrylate, ethylene glycol mono (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth)
Acrylic monomers such as acrylate, 2-hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate; styrene, butadiene, acrylonitrile, chloroprene, isoprene, tertiary vinyl carboxylate having an average of 10 carbon atoms, ethylene, etc. And one or more of these are preferably used. Here, “(meth) acryl” means “acryl” or “methacryl”.

The protective colloid used in the emulsion (co) polymerization of the vinyl acetate resin emulsion is not particularly limited, but includes, for example, partially saponified PVA,
PVA such as fully saponified PVA, carboxyl group-modified PVA, sulfonic acid group-modified PVA, silanol group-modified PVA, etc.
, Hydroxyethyl cellulose, methyl cellulose,
Cellulose derivatives such as carboxymethyl cellulose; α
Α such as a copolymer of olefin and maleic anhydride
-Various water-soluble polymers such as copolymers of olefins and unsaturated carboxylic acids or their derivatives solubilized by basic substances, and one or more of these are preferably used, However, one or more of PVAs are most commonly used.

The average degree of polymerization of the PVAs is not particularly limited, but is preferably from 500 to 3,000, more preferably from 1,000 to 2,500.

When the average degree of polymerization of the PVA is less than 500, the cohesive force of the obtained dried film of the vinyl acetate resin emulsion becomes weak, and the adhesive strength and water resistance of the adhesive composition may be reduced. On the contrary, when the average degree of polymerization of PVAs exceeds 3000, the viscosity of the obtained vinyl acetate resin emulsion becomes too high, and the initial adhesive strength and application workability of the adhesive composition may be reduced. is there.

The degree of saponification of the PVAs is not particularly limited, but is preferably at least 70 mol%, more preferably at least 80 mol%.

If the degree of saponification of PVAs is less than 70 mol%, the water resistance of the resulting vinyl acetate resin emulsion and the adhesive composition may be reduced.

In the present invention, the above-mentioned protective colloid and an emulsifying and dispersing agent such as a surfactant may be used in combination, if necessary, as long as the object of the present invention is not attained.

The above-mentioned surfactant is not particularly restricted but includes, for example, nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants and reactive surfactants in the molecule. And a reactive surfactant containing a double bond having the following.
More than one species is preferably used.

The polymerization catalyst used in the emulsion (co) polymerization of the vinyl acetate resin emulsion is not particularly limited. For example, peroxides such as aqueous hydrogen peroxide; ammonium persulfate, potassium persulfate And persulfates such as sodium persulfate; reducing agents such as tartaric acid, formic acid and oxalic acid; one or more of these are suitably used.

The amount of the polymerization catalyst used is not particularly limited, but is 100 parts by weight of a vinyl acetate monomer, or 100 parts by weight of a total of a vinyl acetate monomer and a polymerizable monomer copolymerizable with the vinyl acetate monomer. It is preferably 0.01 to 2 parts by weight based on part by weight.

The resin content of the vinyl acetate resin emulsion thus obtained is not particularly limited.
It is preferably from 0 to 70% by weight, more preferably from 40 to 60% by weight.

In the present invention, among the above-mentioned vinyl acetate resin emulsions, a vinyl acetate resin emulsion obtained by emulsion polymerization of a vinyl acetate monomer alone or an ethylene copolymer obtained by emulsion copolymerization of a vinyl acetate monomer and ethylene are used. -A vinyl acetate copolymer resin emulsion (hereinafter referred to as "EVA emulsion") and the like are often suitably used.

The above-mentioned EVA emulsion is not particularly limited. For example, the saponification degree is 75 to 97 mol%.
PVA with an average degree of polymerization of about 300 to 2700 is used as a protective colloid, a surfactant or a cellulose derivative such as hydroxyethyl cellulose is used as an emulsifying dispersant, and a vinyl acetate monomer and ethylene are usually used in the presence of a polymerization catalyst. And obtained by copolymerization by an emulsion copolymerization method.

The EVA emulsion may be obtained by further copolymerizing a functional group-containing vinyl monomer having a carboxyl group, an epoxy group, a sulfonic acid group, a hydroxyl group, a methylol group, an alkoxyl group and the like.

Further, the ethylene-vinyl acetate copolymer resin which is a main component of the EVA emulsion is not particularly limited, but preferably has an ethylene content of 15% by weight or more.

The resin content of the EVA emulsion is not particularly limited, but is preferably at least 50% by weight, more preferably at least 60% by weight. When the resin content of the EVA-based emulsion is less than 50% by weight, the adhesive composition obtained may have a low initial adhesive strength.

The calcium carbonate-based filler used in the production method of the present invention may be any of various conventionally known calcium carbonate-based fillers, and is not particularly limited. Examples thereof include heavy calcium carbonate and colloid. Light calcium carbonate, surface-treated finely divided calcium carbonate, and the like can be mentioned, and one or more of these are suitably used. The average particle size, particle shape, presence / absence of surface treatment and the like of the calcium carbonate-based filler are not particularly limited.

In the present invention, the above-mentioned calcium carbonate-based filler is used in the above-mentioned vinyl acetate resin emulsion.
Functions as a neutralizing agent for increasing H.

Therefore, the amount of the calcium carbonate-based filler added to the vinyl acetate-based resin emulsion is not particularly limited, and the pH of the vinyl acetate-based resin emulsion after the calcium carbonate-based filler is added and mixed is adjusted. The pH may be appropriately determined depending on the pH of the vinyl acetate resin emulsion before adding and mixing the calcium carbonate-based filler, the type of the calcium carbonate-based filler, and the like so that the predetermined pH is obtained. Is based on 100 parts by weight of a vinyl acetate resin emulsion, and calcium carbonate-based filler 5
Preferably it is 50 parts by weight.

In the present invention, the above-mentioned calcium carbonate-based filler exhibits a function as a normal inorganic filler in addition to a function as a neutralizer which is an original purpose.

That is, by incorporating the above-mentioned calcium carbonate-based filler into the adhesive composition, in bonding of a poorly adherent porous adherend, irregularities on the surface of the adherend are filled, and the adhesive composition and the adhesive composition are removed. It is possible to prevent the adherend from being bonded only at the convex portion, that is, a so-called “point bonding state”, and to obtain an effect of improving the bonding performance by securing a sufficient bonding area.

In the case where the effect of improving the adhesive performance cannot be sufficiently obtained only with the calcium carbonate-based filler, one or more of various inorganic fillers such as talc, clay, mica powder, silica sand and the like may be filled with the calcium carbonate-based filler. It may be contained in the adhesive composition in combination with the agent.

Next, the anionic urethane resin emulsion used in the production method of the present invention is not particularly limited. For example, a polyol compound, a polyisocyanate compound and one or more active hydrogens in the molecule are used. It can be obtained by dispersing in water water and emulsifying a polyurethane resin synthesized by reacting a functional compound containing a functional group and containing an acid group.

As the polyol compound used for synthesizing the above polyurethane resin, a compound having two or more hydroxyl groups in a molecule is suitably used, and is not particularly limited. Examples thereof include ethylene glycol, diethylene glycol, and propylene. Polyhydric alcohols such as glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane and glycerin; polyether polyols such as polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol; Dicarboxylic acids such as adipic acid, sebacic acid, itaconic acid, maleic anhydride, terephthalic acid, isophthalic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, etc. Glycol, diethylene glycol, propylene glycol, 1,4-butanediol,
1,6-hexanediol, neopentyl glycol,
Reaction with polyol compounds such as 1,2-propanediol, 1,3-propanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, tripropylene glycol, trimethylolpropane, and glycerin Polyester polyols obtained; polylactone-based polyester polyols such as polycaprolactone polyol and poly-β-methyl-δ-valerolactone; polybutadiene polyol or its hydrogenated product, polycarbonate polyol, polythioether polyol, polyacrylate polyol and the like. And
One or more of these are preferably used.

The molecular weight of the above-mentioned polyol compound is not particularly limited, but is preferably in the range of 1000 to 5 in number average molecular weight.
000 is preferred. If the number average molecular weight of the polyol compound is less than 1,000, the resulting dried film of the anionic urethane-based resin emulsion is too hard, and the initial adhesive strength of the adhesive composition may be reduced,
Conversely, if it exceeds 5,000, the dried film of the obtained anionic urethane resin emulsion becomes too soft,
The heat resistance of the adhesive composition may decrease.

As the polyisocyanate compound used for synthesizing the polyurethane resin, an organic polyisocyanate compound having two or more isocyanate groups in a molecule is suitably used, and is not particularly limited. 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,
4,4-trimethylhexamethylene diisocyanate,
2,2,4-trimethylhexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexyl-2,4-diisocyanate, methylcyclohexyl-2, 6-diisocyanate, xylylenediisocyanate, 1,3-bis (isocyanate) methylcyclohexane, tetramethylxylylenediisocyanate,
Transcyclohexane-1,4-diisocyanate,
Aliphatic diisocyanates such as lysine diisocyanate; 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, diphenylmethane-4,
Aromatic diisocyanates such as 4'-diisocyanate, 1,5'-naphthene diisocyanate, tolidine diisocyanate, diphenylmethylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate; lysine ester Triisocyanate, triphenylmethane triisocyanate,
1,6,11-undecane triisocyanate, 1,8
-Isocyanate-4,4-isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, an adduct of trimethylolpropane and 2,4-toluylene diisocyanate, trimethylolpropane and 1,6 Triisocyanates such as adducts with hexamethylene diisocyanate;
More than one species is preferably used.

Further, as the functional compound containing one or more active hydrogens in the molecule used for synthesizing the polyurethane resin and containing an acid group, a hydroxyl group or a primary amino group may be used in the molecule. Alternatively, a functional compound containing a functional group having at least one active hydrogen capable of reacting with an isocyanate group such as a secondary amino group and containing an acid group such as a carboxylic acid group or a sulfonic acid group ( Hereinafter, simply referred to as “functional compound”) are suitably used and are not particularly limited. For example, 3,4-diaminobutanesulfonic acid, 3,6-diamino-2-toluenesulfonic acid, , 6-Diaminobenzenesulfonic acid, N-
Sulfonic acid group-containing compounds such as (2-aminoethyl) -2-aminoethylsulfonic acid; carboxylic acid group-containing compounds such as 2,2-dimethylol lactic acid, 2,2-dimethylol propionic acid, and 2,2-dimethylol valeric acid Compounds and the like are mentioned, and one or more of these are suitably used.

Since the above-mentioned functional compound contains an acid group, an acid group as a hydrophilic group is introduced into the obtained polyurethane resin, thereby exhibiting an effect of improving the stability when the polyurethane resin is dispersed in water. I do.

The polyurethane resin having an acid group introduced into the molecule is called an ionomer structure. The polyurethane resin itself has surface active ability and has excellent self-emulsifying properties. It can be stably dispersed in water without using a molecular hydrophilic compound. Therefore, an adhesive composition containing an anionic urethane resin emulsion obtained by emulsifying this polyurethane resin has excellent water resistance.

In order to further improve the surface activity of the polyurethane resin, an acid group such as a carboxylic acid group or a sulfonic acid group is usually neutralized by a neutralizing agent to form a carboxylic acid group or a sulfonic acid group. It is preferably used in the form of an acid base such as

The neutralizing agent is not particularly restricted but includes, for example, tertiary amine compounds such as triethylamine and triethanolamine and inorganic alkali compounds such as potassium hydroxide and sodium hydroxide. One or more of these are preferably used.

As another method for imparting hydrophilicity to the polyurethane resin, a method using a nonionic compound such as polyethylene glycol may be used in addition to the method for introducing the acid group.

For example, as a raw material for synthesizing a polyurethane resin, a functional group such as a hydroxyl group having at least one active hydrogen capable of reacting with an isocyanate group, a primary amino group or a secondary amino group is contained in a molecule. The above method is achieved by using a compound having a polyethylene glycol skeleton.

However, since the urethane-based resin emulsion used in the production method of the present invention needs to be anionic, the method for imparting hydrophilicity to the polyurethane resin is to introduce the acid group described above or It is necessary to employ any one of the method of introducing the acid group and the method of using the above-mentioned nonionic compound in combination.

As a raw material for synthesizing the above polyurethane resin, various active hydrogen-containing compounds may be used for the purpose of chain elongation, molecular weight control and the like, if necessary, as long as the object of the present invention is not hindered. Is also good.

The active hydrogen-containing compound is not particularly restricted but includes, for example, ethylenediamine,
Polyhydric amines such as 1,4-butanediamine and 1,6-hexanediamine; tertiary amine-containing polyhydric alcohols such as triethanolamine; monoalcohols such as methanol, ethanol and butanol; Of 1
Species or two or more species are suitably used.

Since the polyurethane resin obtained by the above-mentioned method has excellent self-emulsifying properties, it is possible to use an acetone method, a prepolymer mixing method, a ketimine method, a hot melt dispersion method or the like without using an emulsifier or a surfactant. A stable anionic urethane-based resin emulsion can be obtained by the conventionally known method.

The resin content of the anionic urethane resin emulsion thus obtained is not particularly limited, but is preferably 30 to 70% by weight, and 40 to 70% by weight.
More preferably, it is 60% by weight.

The method for producing the adhesive composition according to the present invention comprises:
It is necessary to add and mix a calcium carbonate-based filler to the above-mentioned vinyl acetate-based resin emulsion, adjust the pH of the mixed solution at 25 ° C. to 6 to 9, and then add and mix the anionic urethane-based resin emulsion. It is.
In addition, pH here means the pH measured based on JISK-6833 "General test method of adhesives".

If the pH at 25 ° C. of the vinyl acetate resin emulsion after adding and mixing the above calcium carbonate-based filler is less than 6, the degree of neutralization is insufficient, and the reaction with the anionic urethane resin emulsion is insufficient. When mixing, the viscosity and aggregation may easily occur. Conversely, if the pH at 25 ° C. of the vinyl acetate resin emulsion after adding and mixing the calcium carbonate-based filler exceeds 9, the basicity becomes too high. Thus, the stability of the vinyl acetate resin emulsion may be reduced, or the vinyl acetate resin itself may be hydrolyzed and easily deteriorated.

The method of adding and mixing the calcium carbonate-based filler with the vinyl acetate-based resin emulsion is not particularly limited. For example, a predetermined amount of the vinyl acetate-based resin emulsion in the compounding vessel is stirred with a stirring mixer such as a high-speed stirring machine. While stirring, a predetermined amount of a calcium carbonate-based filler is gradually added thereto, and the mixture may be uniformly dispersed and mixed.

At this time, the calcium carbonate filler may be added as it is, but in order to further improve the dispersibility and mixing properties,
It is preferable to add as a masterbatch prepared by kneading a calcium carbonate-based filler and a small amount of water in advance, or a slurry prepared by dispersing a calcium carbonate-based filler in a small amount of water in advance.

Next, a predetermined amount of an anionic urethane resin emulsion was added thereto while stirring the mixed solution of the vinyl acetate resin emulsion and the calcium carbonate filler obtained above with a stirring mixer. The desired adhesive composition can be obtained by uniformly stirring and mixing.

In the above step, before adding the anionic urethane resin emulsion, the pH of the mixture of the vinyl acetate resin emulsion and the calcium carbonate filler was measured in accordance with JIS K-6833, 25 ° C
Is preferably in the range of 6 to 9.

The adhesive composition according to the production method of the present invention may contain, if necessary, a tackifying resin, a surfactant, a plasticizer, a softener, a filler, a pigment, as long as the object of the present invention is not hindered. Dyes, stabilizers, antioxidants, UV absorbers,
One or more of various additives such as a thickener, an antifoaming agent, a preservative, a fungicide, and an organic solvent may be contained.

The adhesive composition according to the production method of the present invention comprises
It is preferably used mainly for building materials, decorative plywood, woodworking, etc., but is not limited to these applications, and it goes without saying that it may be used for paper processing, fiber processing, general use, and the like.

[0058]

According to the production method of the present invention, a calcium carbonate-based filler is added and mixed as a neutralizing agent to a vinyl acetate-based resin emulsion, and the pH of the vinyl acetate-based resin emulsion containing the calcium carbonate-based filler is specified. After adding to the range, the anionic urethane resin emulsion is added and mixed.Therefore, when the vinyl acetate resin emulsion and the anionic urethane resin emulsion are mixed, a significant increase in viscosity or agglomeration due to ionic shock occurs. Can be prevented, and an adhesive composition having excellent mechanical stability and storage stability, and also having excellent adhesiveness, water resistance, heat resistance, and the like can be easily obtained. .

Further, since aqueous ammonia is not used as a neutralizing agent, the resulting adhesive composition does not cause a decrease in mechanical stability or storage stability due to a decrease in pH over time.

Furthermore, since a basic salt is not used as a neutralizing agent, the resulting adhesive composition does not cause a decrease in water resistance over time.

Accordingly, the adhesive composition according to the production method of the present invention has excellent mechanical stability, storage stability, etc., and also has excellent adhesiveness, water resistance, heat resistance, and the like.

[0062]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the Examples, "parts" means "parts by weight", "%" means "% by weight", and "pH" is measured according to "JISK-6833" unless otherwise specified. PH at 25 ° C. "

(Example 1)

(1) Weight of vinyl acetate resin emulsion
In a reaction vessel equipped with a mixing stirrer, a reflux condenser, a thermometer and a dropping funnel, 111 parts of water and polyvinyl alcohol (trade name "Kuraray PVA-CST", average polymerization degree 1700, saponification degree 96 mol%, manufactured by Kuraray Co., Ltd.) 11 parts were charged and heated at 90 ° C. for 1 hour with stirring to obtain an aqueous solution of polyvinyl alcohol. Next, the aqueous solution was cooled to 70 ° C., and 8 parts of a vinyl acetate monomer and 0.2 parts of a polymerization catalyst (0.1 part of hydrogen peroxide solution and 0.1 part of tartaric acid) were added thereto to perform initial polymerization. I let you. Next, 92 parts of a vinyl acetate monomer and 0.8 parts of a polymerization catalyst (0.4 parts of a hydrogen peroxide solution and 0.4 parts of tartaric acid) were added dropwise over 3 hours, emulsion polymerization was performed at 70 ° C, and then 90 ° C. For 1 hour, pH4, resin content 5
A 0% vinyl acetate resin emulsion was obtained.

(2) Preparation of Adhesive Composition While stirring 100 parts of the vinyl acetate resin emulsion obtained above with a high-speed stirrer, a heavy calcium carbonate-based filler (trade name: Calcium 1
Grade, manufactured by Sankyo Seiko Co., Ltd.) was gradually added, and the mixture was uniformly stirred and mixed to obtain a mixed liquid of a vinyl acetate resin emulsion and a heavy calcium carbonate-based filler. The pH of the resulting mixture was 6.6. To 115 parts of the mixture obtained above, 0.5 part of dialkyl sulfosuccinate soda salt (trade name “Sammorin OT-70”, solid content 70%, manufactured by Sanyo Chemical Industries, Ltd.) was added, and the mixture was uniformly mixed. Stir and mix.
Next, 100 parts of the vinyl acetate resin emulsion in 115.5 parts of the mixture was mixed with an anionic urethane resin emulsion (trade name “Hydran HW-333”, p.
H7, resin content 40%, manufactured by Dainippon Ink and Chemicals, Inc.) 30
Were added and mixed uniformly with stirring. Furthermore, a thickener (trade name "Viscalex AT-77", Allied
0.1 parts of Colloids Limited and 5 parts of toluene were added and uniformly stirred and mixed to obtain an adhesive composition.

(3) Evaluation Performance of the adhesive composition obtained as described above ｛Adhesive strength in normal state,
The coating workability (mechanical stability) and aging stability (storage stability) were evaluated by the following methods. The results were as shown in Table 2.

The adhesive composition was applied to a 3 mm-thick JAS1 type Rawan plywood using a normal adhesive strength rubber roller so that the application amount was 100 g / m ² . Then, immediately after, the back surface of a semi-rigid vinyl chloride decorative sheet having a thickness of 0.2 mm, the surface of which is wood-grained printed, is stuck, and the pressure: 40 kg / scale angle, temperature:
Room temperature, time: Pressing was performed under pressing conditions of 24 hours. further,
After pressing and releasing, the cured product was left to stand at room temperature for one week for curing to obtain a vinyl chloride decorative plywood.

The obtained vinyl chloride decorative plywood is 25 mm in width.
To prepare a test piece for measurement, and using a Tensilon-type tensile tester at a peeling speed of 200 mm / min.
An 80-degree peel test was conducted to determine the normal adhesive strength (Kg / 25
mm). The measurement was performed in an atmosphere of 20 ° C. and 65% RH.

Coating workability (mechanical stability) Using a rubber roller, the adhesive composition was applied to a 30 cm square JAS1 Rawan plywood so as to have an application amount of 100 g / m ^2, and the roll release property and The elongation of the adhesive composition on the Rawan plywood was sensorially determined, and the coating workability (mechanical stability) was evaluated by a three-point method based on the criteria shown in Table 1 below.

[0070]

[Table 1]

Stability Over Time (Storage Stability) The initial viscosity (25 ° C.) and the initial pH (25 ° C.) of the adhesive composition were measured in accordance with JIS K-6833. Next, the adhesive composition was placed in a sealed container and left for 30 days in an atmosphere of 40 ° C., and similarly, the viscosity after aging (25 ° C.) and the pH after aging (25 ° C.) were measured. .

(Example 2) In the preparation of the adhesive composition, an ethylene-vinyl acetate copolymer resin emulsion (trade name "SUMICA FLEX 455", trade name: An adhesive composition was obtained in the same manner as in Example 1 except that 100 parts of an ethylene content of about 18%, a pH of 5, a resin content of 55%, and Sumitomo Chemical Co., Ltd. were used. still,
"Sumika Flex 455" and "Calcium Carbonate First Class"
Was 6.9.

(Comparative Example 1) In the preparation of the adhesive composition, 0.15 parts of aqueous ammonia (25%) was added as a neutralizing agent instead of 15 parts of “calcium carbonate first grade”.
An adhesive composition was obtained in the same manner as in Example 1 except that “Sammorin OT-70” was not added.
In addition, vinyl acetate resin emulsion and ammonia water (25
%) Was 7.0.

Comparative Example 2 An adhesive composition was obtained in the same manner as in Example 1 except that no neutralizing agent was added in the preparation of the adhesive composition.
When "3" was added and mixed, a remarkable increase in viscosity was observed.
The pH of the obtained adhesive composition was 5.5.

The performance of the three types of adhesive compositions obtained in Example 2 and Comparative Examples 1 and 2 was evaluated in the same manner as in Example 1. The results were as shown in Table 2.

[0076]

[Table 2]

As shown in Table 2, the adhesive composition of Example 1 or Example 2 according to the production method of the present invention has excellent normal adhesive strength and coating workability (mechanical stability). In addition, the increase in viscosity and the decrease in pH after aging were small, and the storage stability was excellent.

On the other hand, the adhesive composition of Comparative Example 1 using ammonia water as a neutralizing agent for the vinyl acetate resin emulsion has a normal adhesive strength and coating workability (mechanical stability).
Was excellent, but the viscosity increase and pH decrease after aging were large, and the storage stability was poor.

The adhesive composition of Comparative Example 2 in which a neutralizing agent was not added to the vinyl acetate resin emulsion had excellent normal-state adhesive strength, but poor coating workability (mechanical stability). Further, it aggregated during standing at 40 ° C. for 30 days, and the storage stability was extremely poor.

[0080]

As described above, according to the production method of the present invention, a remarkable increase in viscosity and generation of aggregates do not occur during production, and excellent mechanical stability and storage stability are obtained.
In addition, it is possible to easily obtain an emulsion-type adhesive composition having excellent adhesiveness, water resistance, heat resistance, and the like.

The adhesive composition obtained by the production method of the present invention is excellent in mechanical stability, storage stability, etc., and also has excellent adhesiveness, water resistance and heat resistance. , For decorative plywood, woodwork, etc.

Claims (1)

[Claims] 1. A method in which a calcium carbonate-based filler is added to and mixed with a vinyl acetate-based resin emulsion, the pH of the mixture at 25 ° C. is adjusted to 6 to 9, and then an anionic urethane-based resin emulsion is added and mixed. A method for producing an adhesive composition, comprising: