JPH09217050A - Waterborne adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a waterborne adhesive composition excellent in coatability and mechanical stability and further dry and print laminating properties. SOLUTION: This waterborne adhesive composition comprises a resin particle having -30 to ±10 deg.C glass transition temperature and <=100nm average particle diameter, has <=500mPa.s viscosity at 25 deg.C and 0.8-1.2 thixotropic index and further comprises an epoxy resin containing two or more epoxy groups in the molecule.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous adhesive composition. More specifically, for the purpose of protecting the surface of printed paper, publications, posters, packaging materials, and other paper products, imparting water resistance and oil resistance, and beautifying, a flexible substrate such as a resin film is provided on these surfaces. A water-based adhesive for lamination that can be suitably used in the production of so-called print laminates obtained by laminating materials, resin film-to-resin laminates, metal films such as resin films and aluminum, and so-called dry laminates such as aluminum foil laminates. Agent composition.

[0002]

2. Description of the Related Art In recent years, transparent resin films have been laminated on the surface of paper products such as printed paper, publications and posters for the purpose of surface protection.

When laminating the transparent resin film on the surface of a paper product as described above, an organic solvent type adhesive such as a urethane type adhesive has been conventionally used. However, the adhesive requires an organic solvent. Therefore, from the viewpoint of air pollution, industrial pollution such as odor, occupational hygiene, storage and handling restrictions under the Fire Service Act, and danger of fire due to explosion and ignition,
In recent years, some water-based adhesives containing no organic solvent have been used.

As the water-based adhesive, a water-based adhesive obtained by blending a urethane resin emulsion with an epoxy resin as a curing agent, and a water-based adhesive obtained by blending an ethylene-vinyl acetate copolymer emulsion with an epoxy resin and an amine compound as a curing agent. There are agents and the like, but all of these water-based adhesives have a problem that they have poor coatability because they are water-based.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above prior art, and an object of the present invention is to provide an aqueous adhesive composition having excellent coatability and mechanical stability.

Another object of the present invention is to provide an aqueous adhesive composition having excellent dry laminating property and print laminating property.

[0007]

The present invention contains resin particles having a glass transition temperature of −30 to 10 ° C. and an average particle diameter of 100 nm or less, and a viscosity at 25 ° C. of 50.
It is 0 mPa * s or less, and the thixotropic index is 0.8 to 1.2.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the aqueous adhesive composition of the present invention contains resin particles having a glass transition temperature of −30 to 10 ° C. and an average particle diameter of 100 nm or less, and 25 ° C. The viscosity is 500 mPa · s or less and the thixotropic index is 0.8 to 1.2.

As described above, the aqueous adhesive composition of the present invention uses resin particles having a specific glass transition temperature and a specific average particle diameter, and has a specific viscosity and a specific thixotropic index. It has excellent coating stability, mechanical stability, dry laminating property and print laminating property.

The glass transition temperature of the resin particles used in the present invention is -30 ° C. or higher, preferably -15 ° C. or higher, in order to impart appropriate tackiness and improve peel strength. Immediately after), the temperature is set to 10 ° C. or lower, preferably −5 ° C. or lower, in order to improve the adhesion.

The average particle size of the resin particles is set to 100 nm or less, preferably 70 nm or less in order to bring the resin particles closer to a uniform dissolved state and reduce the structural viscosity. If the average particle size of the resin particles is too small, the viscosity will be high and the transfer of the aqueous adhesive composition to the substrate may be non-uniform.
It is preferable that it is above.

The water-based adhesive composition of the present invention contains the above-mentioned resin particles. The content of the resin particles in the water-based adhesive composition is such that the water-based adhesive composition has a specific viscosity and Adjusted to have a specific thixotropic index. The content (solid content) of the resin particles in the aqueous adhesive composition varies depending on the average particle diameter of the resin particles and the like, and therefore cannot be unconditionally determined, but is usually 30 to 50% by weight. It is preferable.

The viscosity of the water-based adhesive composition of the present invention (B-type viscometer, 25 ° C.) is 500 mP in order to coat it evenly on a substrate and make it difficult for bubbles to be contained in the adhesive composition.
It is not more than a · s, preferably not more than 100 mPa · s. The lower limit of the viscosity of the aqueous adhesive composition is not particularly limited, but is usually 1 mPa · s or more, preferably 10 mPa · s or more.

When the thixotropic index of the water-based adhesive composition of the present invention is out of the range of 0.8 to 1.2, the transfer of the water-based adhesive composition to the substrate becomes uneven, In addition, the leveling property after application becomes poor. Therefore, the thixotropic index of the present invention is
From this viewpoint, 0.8 to 1.2, preferably 0.9 to
It is set to 1.1.

The aqueous adhesive composition of the present invention can be prepared, for example, as follows.

That is, for example, 3 to 40% by weight of a hydroxyl group-containing unsaturated monomer, 0.5 to 5% by weight of a carboxyl group-containing unsaturated monomer, and an alkyl (meth) acrylate whose alkyl group has 1 to 12 carbon atoms. 50-95% by weight and 0-40% by weight of other monomers copolymerizable with these monomers
It can be prepared by emulsion-polymerizing a polymerization component consisting of the above in the presence of a surfactant.

The hydroxyl group-containing unsaturated monomer is an unsaturated monomer having at least one hydroxyl group in the molecule and a polymerizable double bond.

Typical examples of the hydroxyl group-containing unsaturated monomer are, for example, hydroxylethyl (meth) acrylate, 2-hydroxy-n-propyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate and 3-hydroxypropyl. (Meth) acrylate, hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, glycerin monoallyl ether, trimethylolpropane monoallyl ether, allyl alcohol, etc. Can be given. These hydroxyl group-containing unsaturated monomers may be used alone or in admixture of two or more.

The water-based adhesive composition of the present invention is usually used after sequentially undergoing coating, drying and thermocompression bonding. If the glass transition temperature when the hydroxyl group-containing unsaturated monomer is a homopolymer is too high, the glass transition temperature of the resin particles contained in the aqueous adhesive composition becomes high, and the aqueous solution after the operation is Since the tackiness of the adhesive composition and the adhesion to the adherend are lowered, the final adhesive strength is lowered.

From this viewpoint, therefore, it is preferable to use a hydroxyl group-containing unsaturated monomer having a glass transition temperature of 0.degree.

Specific examples of the hydroxyl group-containing unsaturated monomer having a glass transition temperature of 0 ° C. or lower when it is made into the above homopolymer are, for example, 2-hydroxyethyl acrylate and 2-hydroxyethyl acrylate.
Examples thereof include hydroxypropyl acrylate and 4-hydroxybutyl acrylate. These monomers are
Both have a glass transition temperature of 0 ° C. when made into a homopolymer.
Since it is the following, it does not impair the adhesiveness and has excellent affinity with water molecules (water solubility).
It can be preferably used in the present invention. Of these, 4-hydroxybutyl acrylate is particularly suitable for use in the present invention because it can impart excellent print laminating properties to the resulting aqueous adhesive composition.

The amount of the hydroxyl group-containing unsaturated monomer may be adjusted so as to be contained in the polymerization component in an amount of 3% by weight or more, particularly 5% by weight or more, from the viewpoint of improving mechanical stability and viscosity. In order to prevent the viscosity from becoming too high, it is preferable to adjust the content to be 40% by weight or less, especially 10% by weight or less.

Typical examples of the unsaturated monomer containing a carboxyl group include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid and 2-acryloyloxypropionic acid. These carboxyl group-containing unsaturated monomers may be used alone or in combination of two or more. Among these unsaturated monomers containing a carboxyl group, it has excellent copolymerizability,
Acrylic acid is easy to be distributed on the surface of the resin particles and has excellent cross-linking property with the epoxy resin described later.
It can be used particularly preferably.

The amount of the carboxyl group-containing unsaturated monomer is 0.5% by weight or more in the polymerization component, in order to suppress the generation of coarse particles and to enhance the reactivity with, for example, the epoxy resin described later. The content is preferably adjusted to 1% by weight or more, and in order to improve the adhesiveness, it is preferably adjusted to 5% by weight or less, especially 2% by weight or less.

Typical examples of the alkyl (meth) acrylate having 1 to 12 carbon atoms in the alkyl group are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl ( (Meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth)
Examples thereof include acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate. These alkyl (meth) acrylates can be used alone or in combination of two or more. Among these alkyl (meth) acrylates, an alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms is preferable from the viewpoint of copolymerizability.

The amount of the alkyl (meth) acrylate having 1 to 12 carbon atoms in the alkyl group is 50% by weight or more in the polymerization component in order to improve the adhesiveness, especially 55.
It is preferable to adjust the content to be contained by weight% or more,
From the viewpoint of viscosity, it is preferable to adjust the content to 95% by weight or less, especially 90% by weight or less.

The hydroxyl group-containing unsaturated monomer, the carboxyl group-containing unsaturated monomer and the alkyl group each have 1 to 10 carbon atoms.
Representative examples of other monomers (hereinafter referred to as other monomers) copolymerizable with the alkyl (meth) acrylate of 12 (these monomers) include, for example, styrene, α-methylstyrene, and (meth). ) Acrylonitrile, acrolein, vinyl acetate, versatic acid vinyl ester, (meth) acrylamide, N-methylol (meth) acrylamide, etc., divinylbenzene, allyl (meth) acrylate, diallyl ether, allyl glycidyl ether, diallyl maleate, adipine Acid diallyl, glycidyl (meth) acrylate, triallyl (iso) cyanurate, diallyl (iso) phthalate, diallyl terephthalate, trimethylolpropane diallyl ether, glycerol diallyl ether, diglycerol diallyl ether Diethylene glycol diallyl ether, diglycerol triallyl ether, tripropylene glycol diacrylate, polyethylene glycol diacrylate, polyfunctional unsaturated monomers such as polypropylene glycol diacrylate and the like. These other monomers can be used alone or in admixture of two or more. Among these other monomers, styrene has a large hydrophobicity and is likely to be localized inside the resin particles. Therefore, the alkyl group having a carbon number of 1 to 12 is a component that imparts adhesiveness. The (meth) acrylate and the hydroxyl group-containing unsaturated monomer are preferable in that they can be easily distributed on the surface of the resin particles, and the polyfunctional unsaturated monomer is crosslinked in the particles to improve the cohesive force (adhesive force) of the resin. It can be preferably used from the standpoint of enhancing.

The amount of the above-mentioned other monomer may not be contained when the other monomer is an optional component, so the content in the polymerization component is 0% by weight. is there. In order to improve the cohesive force of the resin and the heat resistance, water resistance, solvent resistance, etc. of the resulting water-based adhesive composition, 0.5% by weight of the other monomer is contained in the polymerization component.
It is preferable that the content is 40% by weight or less, especially 35% by weight or less, in order not to reduce the adhesive strength.

The monomer composition of the above-mentioned polymerization component is prepared so that the glass transition temperature of the obtained resin particles is -30 to 10 ° C.

The aqueous adhesive composition of the present invention can be prepared by emulsion polymerization of the above-mentioned polymerization components.

The emulsion polymerization may be carried out by a conventional method,
For example, in a reaction vessel charged with an appropriate amount of water and a suitable surfactant in advance, the polymerization component and the polymerization initiator, and if necessary, a chain transfer agent are charged, and the system is emulsified under stirring, and then the predetermined reaction is performed. It can be prepared by polymerizing under conditions.

The method of supplying the polymerization component is not particularly limited, and examples thereof include batch charging, divided charging, continuous dropping charging and the like.

The amount of the above-mentioned polymerizing component supplied is such that the concentration of the polymerizing component during the polymerization is usually 15 to 60% by weight, especially 30.
It is preferable to adjust the content to be 50% by weight.

A surfactant is used to emulsify the above-mentioned polymerization component.

Examples of the surfactant include anionic surfactants such as alkyl sulfate, alkylbenzene sulfonate, polyoxyethylene alkyl sulfate, polyoxyethylene alkylphenyl ether sulfate and sodium dialkylsulfosuccinate; polyoxyethylene alkyl ether, poly Nonionic surfactants such as oxyethylene alkyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene alkylamine ether, ethylene oxide-propylene oxide block copolymer, sorbitan derivative, polyoxyethylene fatty acid ester; allyl group in the molecule, Radical-polymerizable reactive surfactant containing a polymerizable double bond such as (meth) acrylic group and maleic acid And the like. These surfactants can usually be used alone or in admixture of two or more.

Usually, the amount of the surfactant used is preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the polymerization component. The average particle diameter of the obtained resin particles can be adjusted by adjusting the amount of such a surfactant used. Generally, the larger the amount of the surfactant used, the smaller the average particle size of the obtained resin particles, and the smaller the amount of the surfactant used, the larger the average particle size.

As the polymerization initiator used in the polymerization, a commonly used radical polymerization initiator can be used.

Typical examples of the polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate; 2,2-azobisisobutyronitrile and 2,2-azobis (2,4-dimethyl) valero. Examples thereof include azo compounds such as nitrile; peroxides such as t-butylhydroxyperoxide, benzoylperoxide and lauroylperoxide. These polymerization initiators can usually be used alone or in admixture of two or more.

The amount of the polymerization initiator used is usually 0.1 to 3 parts by weight, particularly 0.3 to 1 part by weight, relative to 100 parts by weight of the polymerization component.

Of the above-mentioned polymerization initiators, persulfate,
When a peroxide or the like is used, a radical is generated by the redox reaction, and therefore, for example, by using a reducing agent as needed, the polymerization at a temperature lower than the temperature range in which the polymerization initiator effectively acts. Is possible. The rate of such radical generation can be controlled by the type and amount of the reducing agent.

Representative examples of the reducing agent include salts of lower oxides or lower oxygen acids such as sodium bisulfite and sodium sulfite; organic compounds such as L (+)-ascorbic acid, formic acid and oxalic acid. To be These reducing agents can be used alone or in combination of two or more.

The amount of the reducing agent used is usually about 0.1 to 100 parts by weight, preferably about 10 to 50 parts by weight, based on 100 parts by weight of the polymerization initiator.

In the present invention, the chain transfer agent optionally used may be one used in ordinary emulsion polymerization.

Typical examples of the chain transfer agent include mercaptans such as methyl mercaptan, butyl mercaptan, octyl mercaptan and dodecyl mercaptan, alcohols such as methanol, ethanol, isopropanol and hexanol, and α-methylstyrene dimer. To be These chain transfer agents can be used alone or in combination of two or more.

The amount of the chain transfer agent used is usually about 0.05 to 3 parts by weight, preferably about 0.1 to 1 part by weight, based on 100 parts by weight of the polymerization component.

When polymerizing the above-mentioned polymerization components, the reaction temperature is usually about 20 to 95 ° C., and the reaction time is usually about 2 to 8 hours.

Thus, the aqueous adhesive composition of the present invention can be obtained by emulsion polymerization of the above-mentioned polymerization components.

The pH of the aqueous adhesive composition of the present invention
Is 7 from the viewpoint of improving the stability of particles and preventing rust of coating machines.
It is preferably about 8 to 8. When adjusting the pH, for example, ammonia water, monoethanolamine, dimethylamine, triethylamine or the like can be used.

As described above, the aqueous adhesive composition of the present invention contains resin particles having a glass transition temperature of −30 to 10 ° C. and an average particle diameter of 100 nm or less, and 25 ° C.
The viscosity is 500 mPa · s or less and the thixotropic index is 0.8 to 1.2.

The reason why the water-based adhesive composition of the present invention has good viscosity and excellent coatability is considered to be based on the following reasons.

In general, an organic solvent solution of a synthetic resin and an aqueous solution of a synthetic resin are respectively obtained by uniformly dissolving the synthetic resin in a solvent and have a Newtonian viscosity. On the other hand, the water-dispersed synthetic resin, so-called resin emulsion, has a structural viscosity because the synthetic resin is dispersed in water without being dissolved.

The structural viscosity of the resin emulsion is reduced,
As a means of approaching the Newtonian viscosity, it is conceivable to reduce the particle size of the dispersed resin to bring the resin closer to a uniform dissolved state, but in this case, it becomes difficult to stably disperse the resin particles, and further At present, the viscosity of the system deviates from the practical range even if gelation or aggregation occurs, or even if gelation or aggregation does not occur. Further, using a large amount of a carboxyl group-containing unsaturated monomer, the resin on the particle surface is dissolved by neutralization after particle formation, so-called hydrosol formation is also an effective means of improving Newtonian viscosity, In this case, a large amount of the carboxyl group-containing component having a high glass transition temperature is distributed on the particle surface, so that it cannot be an effective means in the field where dry laminating property is required. Further, by using a large amount of a water-soluble unsaturated monomer such as a carboxyl group-containing unsaturated monomer, a resin prepared to be uniformly dissolved in water, a so-called water-soluble resin, also has a glass transition temperature. The use of such a water-soluble resin is not an effective means for solving problems, because a large amount of high carboxyl group-containing components and the like are contained in the resin, and there are many restrictions on the resin components for dissolving in water. It can't be.

On the other hand, in the present invention, resin particles obtained by emulsion polymerization of a polymerization component containing a hydroxyl group-containing unsaturated monomer having a glass transition temperature of 0 ° C. or less when formed into a homopolymer. In the case of using, since hydroxyl groups are present on the surface of the resin particles, water molecules are distributed near the surface of the resin particles due to the attractive force of the hydroxyl groups. As a result, the resin particles come to have a large amount of water molecules in the surface layer (hydrated layer), and the mechanical stability of the aqueous adhesive composition of the present invention is improved. Further, due to the buffering action of the hydration layer existing in the surface layer, the structural viscosity is reduced, the viscosity is low, and the resin particles have a small viscosity such as an average particle diameter of 100 nm or less, and are stable. It is speculated that an aqueous adhesive composition having a Newtonian viscosity can be obtained.

In the present invention, in order to impart curability to the aqueous adhesive composition, the aqueous adhesive composition may contain an epoxy resin containing two or more epoxy groups in the molecule. Good.

As the epoxy resin containing two or more epoxy groups in the molecule, a liquid epoxy resin or a solid epoxy resin which can be emulsified by heat melting can be used. As a typical example of the epoxy resin, for example, an epoxy resin aqueous emulsion obtained by emulsifying a bisphenol A type epoxy resin or a novolac type epoxy resin with polyvinyl alcohol, a nonionic surfactant, an anionic surfactant; ethylene glycol. Diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, bisphenol A-ethylene oxide-epichlorohydrin polycondensate, etc. However, the present invention is not limited to such examples. In addition, these epoxy resins can be used individually or in mixture of 2 or more types. Among these epoxy resins, water-soluble or epoxy resins exhibiting self-emulsifying property in water,
Among them, the emulsion of bisphenol A type epoxy resin is
It is particularly preferable in the present invention because it has excellent adhesion to a substrate.

Amount of the epoxy resin used (solid content)
Is 3 to 100 parts by weight of the solid content of the water-based adhesive composition in order to impart sufficient curability and adhesive strength.
It is preferable that the amount is not less than 5 parts by weight, especially 5 parts by weight or more, and in order to prevent unreacted substances from remaining in the coating film formed by using the water-based adhesive composition and reducing the initial adhesive strength, It is preferably 30 parts by weight or less, especially 20 parts by weight or less.

Further, in the present invention, in order to accelerate the curing of the epoxy resin, the aqueous adhesive composition contains
Epoxy resin cure accelerators can be used.

Typical examples of the epoxy resin curing accelerator include tertiary amines such as triethylamine, benzyldimethylamine, dimethylaminomethylphenol and trisdimethylaminomethylphenol; 1,3-
An acid hydrazide having a hydantoin skeleton such as bis (hydrazinocarboethyl) -5-isopropylhydantoin; carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, isophthalic acid, isophthalic acid A hydrazine derivative having at least two hydrazide groups in the molecule, such as dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, itaconic acid dihydrazide, and citric acid trihydrazide;
Examples thereof include imidazole compounds such as methylimidazole, borate esters, Lewis acids, organic metal compounds, organic acid metal salts and enamines. These epoxy resin curing accelerators can be used alone or in admixture of two or more. Among these epoxy resin curing accelerators, acid hydrazides having a hydantoin skeleton, carbohydrazide, adipic acid dihydrazide, citric acid trihydrazide and imidazole compounds are particularly preferable in that ink discoloration, odor and the like are unlikely to occur. It can be used for.

The amount of the epoxy resin curing accelerator used is
In order to cure the epoxy resin sufficiently and improve the initial adhesive strength, the solid content of the epoxy resin is 100%.
It is preferably 1 part by weight or more, especially 3 parts by weight or more with respect to parts by weight, and the pot life is prevented from becoming too short, and the curing reaction does not proceed too fast so that the initial adhesive performance is not deteriorated. Therefore, the amount is preferably 30 parts by weight or less, especially 15 parts by weight or less.

To the water-based adhesive composition of the present invention, a water-soluble solvent such as alcohols, cellosolves, carbitols, etc. may be added in order to adjust the drying speed and the surface tension. Good.

The water-based adhesive composition of the present invention is excellent in coatability, and further excellent in mechanical stability, dry laminating property and print laminating property. Therefore, for example, production of print laminating, dry laminating and the like. It can be suitably used as an adhesive at the time.

[0062]

EXAMPLES Next, the water-based adhesive composition of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 In a 1 liter flask equipped with a stirrer, a reflux condenser and a raw material inlet, 350 g of water and Eleminol ES-70 (manufactured by Sanyo Chemical Industry Co., Ltd., anionic interface as a surfactant) were used. 10g of activator was charged and the internal temperature was adjusted to 75
0.3 g of ammonium persulfate as a radical polymerization initiator and sodium bisulfite as a reducing agent of 0.
After adding 05 g, n-butyl acrylate 110
g, methyl methacrylate 66 g, 2-hydroxyethyl acrylate 20 g and acrylic acid 4 g were added dropwise over 2 hours.

After completion of the dropping, in order to reduce the residual monomer, 0.2 g of t-butylhydroxyperoxide as a free radical generator and L (+)-as a reducing agent.
0.1 g of ascorbic acid was added, and the mixture was aged at 80 ° C. for 2 hours.

The obtained emulsion was cooled to 25 ° C., and 2.5 g of 25% ammonia water was added as a neutralizing agent while continuing stirring to give a milky white aqueous adhesive having a pH of 7.8 and a solid content of 36.3% by weight. An agent composition was obtained.

The glass transition temperature and average particle diameter of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined according to the following methods. Table 1 shows the results.

(1) Glass Transition Temperature of Resin Particles 1 g of the obtained water-based adhesive composition was prepared with release paper 1
The sample was placed in a container with a side of 2 cm, spread evenly, and allowed to stand in an electric thermostat of 80 ° C. for 16 hours, and then a differential scanning calorimeter (DSC220C manufactured by Seiko Instruments Inc.) was used to raise the temperature at 10 ° C./min. ． Measure with

(2) Average particle size of resin particles The obtained aqueous adhesive composition was filtered through a 200-mesh stainless steel sieve, and then a laser particle size analysis system (LPA-3000 / Otsuka Electronics Co., Ltd.). 3100) at 20 ° C. Note that ion-exchanged water is used to dilute the sample (the filtered water-based adhesive composition).

(3) Viscosity of Water-based Adhesive Composition 1 kg of the water-based adhesive composition at 25 ° C. was placed in a 1-liter glass beaker, and a B-type viscometer (B, manufactured by Tokyo Keiki Co., Ltd.
Type viscometer, type BM), rotor speed 6rp
Measure in m.

(4) Thixotropic Index of Aqueous Adhesive Composition 1 kg of the aqueous adhesive composition at 25 ° C. was placed in a 1 liter glass beaker, and a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd., B
Type viscometer, type BM), rotor speed 6rp
After measuring the viscosity A at m, the viscosity B is measured at the rotation speed of 60 rpm using the same rotor as it is.

A value obtained by dividing the viscosity A by the viscosity B is defined as a thixotropic index. Next, as physical properties of the obtained water-based adhesive composition, coatability and mechanical stability were examined according to the following methods. Table 1 shows the results.

(A) Coatability A water-based adhesive composition whose solid content was adjusted to 30% by weight was prepared.
Using an automatic film applicator (manufactured by Yasuda Seiki Seisakusho, No. 542-AB), a coating speed of 10 m / min. , Weight No. 2 bar coater N
o. Under the conditions of No. 7, it was applied to the corona discharge treated surface of a biaxially oriented polypropylene film (San Orient PB-260 manufactured by Yuka Sansho Co., Ltd.), and cissing and leveling were visually observed, and the following evaluation criteria Evaluation based on

(Repelling) Evaluation Criteria A: Repelling is not observed at all. B: 10 or less cissings are seen per 100 cm ² . C: 11 or more cissings are seen per 100 cm ² .

(Leveling) Evaluation Criteria A: No coating is seen by the coater. B: The coating by the coater is slightly observed. C: The coating by the coater is clearly seen.

(B) Mechanical Stability Aqueous adhesive composition having a solid content of 30% by weight was prepared,
After filtering through a 200-mesh stainless steel sieve, 50 g of the obtained filtrate is rotated for 20 minutes under the conditions of a load of 20 kg and a rotation speed of 1000 rpm using a Maron mechanical stability tester.

Next, the rotating disk inside the tester is removed, and the attached resin is washed into the sample container. At this time, the dry film adhered to the upper surface and the side surface of the rotating disk is removed without being added to the solidified material.

After that, the aqueous adhesive composition in the sample container is filtered through a 200-mesh stainless steel sieve whose weight has been weighed in advance to wash out the resin adhering to the sample container.

Next, the sample container is disassembled, and the solidified material between the liner and the bottom plate is also washed out on the stainless steel sieve to completely collect the solidified material.

After that, it was washed with distilled water until the non-solidified water-based adhesive composition on the stainless steel sieve disappeared, and then the water was well drained off and dried in a thermostatic oven at 105 to 110 ° C. for 3 hours. Then, allow to cool to room temperature in a desiccator, then weigh.

Next, the solidification rate is expressed by the formula:

[0081]

[Equation 1]

Calculation based on the above, and the average value of the above three operations was used as a guideline for mechanical stability.

The closer the average value of the solidification rate is to 0, the better the mechanical stability. Generally, when the average value of the solidification rate is 0.03 or less, the excellent mechanical stability is evaluated. To be done.

Example 2 250 g of water and Eleminol ES-70 (manufactured by Sanyo Kasei Co., Ltd., anionic interface as a surfactant) were placed in a 1 liter flask equipped with a stirrer, a reflux condenser and a raw material inlet. 10g of activator was charged and the internal temperature was adjusted to 75
0.3 g of ammonium persulfate as a radical polymerization initiator and sodium bisulfite as a reducing agent of 0.
After adding 05 g, n-butyl acrylate 110
g, 66 g of styrene monomer, 20 g of 2-hydroxyethyl methacrylate and 4 g of acrylic acid, eleminol ES-705 5 g, and water 100 g.
What was mechanically emulsified in advance was added dropwise over 2 hours.

After the dropping, in order to reduce the residual monomer, 0.2 g of t-butylhydroxyperoxide as a free radical generator and L (+)-as a reducing agent.
0.1 g of ascorbic acid was added, and the mixture was aged at 80 ° C. for 2 hours.

The obtained emulsion was cooled to 25 ° C., and 2.5 g of 25% aqueous ammonia was added as a neutralizing agent while continuing stirring to give a milky white aqueous adhesive having a pH of 7.6 and a solid content of 36.0% by weight. An agent composition was obtained.

The glass transition temperature and average particle size of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined in the same manner as in Example 1. . Table 1 shows the results.

Next, as the physical properties of the obtained aqueous adhesive composition, coating properties and mechanical stability were examined in the same manner as in Example 1. Table 1 shows the results.

Example 3 In a 1 liter flask equipped with a stirrer, a reflux condenser and a raw material charging port, 250 g of water and Aqualon HS-10 as a surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., reactivity) Surfactant) 2 g was charged, and while keeping the internal temperature at 75 ° C., ammonium persulfate 0.3 g as a radical polymerization initiator and sodium bisulfite 0.05 g as a reducing agent.
After addition of 2-ethylhexyl acrylate 46
g, 80 g of ethyl acrylate, 60 styrene monomers
g and 4 g of acrylic acid were added dropwise over 2 hours.

Immediately after the dropwise addition, 10 g of 4-hydroxybutyl acrylate was further added dropwise over 30 minutes.

After the dropping, in order to reduce the residual monomer, 0.2 g of t-butylhydroxyperoxide as a free radical generator and L (+)-as a reducing agent.
0.1 g of ascorbic acid was added, and then 2.5 g of 25% ammonia water was added as a neutralizing agent to obtain a milky white aqueous adhesive composition having a pH of 7.3 and a solid content of 35.9% by weight.

The glass transition temperature and average particle diameter of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined in the same manner as in Example 1. . Table 1 shows the results.

Next, as the physical properties of the obtained aqueous adhesive composition, coating properties and mechanical stability were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 An aqueous adhesive composition was obtained in the same manner as in Example 1 except that 20 g of 2-hydroxyethyl acrylate was not used.

The glass transition temperature and average particle size of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined in the same manner as in Example 1. . Table 1 shows the results.

Next, as the physical properties of the obtained water-based adhesive composition, coating properties and mechanical stability were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 An aqueous adhesive composition was obtained in the same manner as in Example 2 except that 20 g of 2-hydroxyethyl methacrylate was not used.

The glass transition temperature and average particle diameter of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined in the same manner as in Example 1. . Table 1 shows the results.

Next, as the physical properties of the obtained water-based adhesive composition, coating properties and mechanical stability were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 An aqueous adhesive composition was obtained in the same manner as in Example 3, except that 10 g of 4-hydroxybutyl acrylate was not used.

The glass transition temperature and average particle diameter of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined in the same manner as in Example 1. . Table 1 shows the results.

Next, as the physical properties of the obtained water-based adhesive composition, coating properties and mechanical stability were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 4 In a 1 liter flask equipped with a stirrer, a reflux condenser and a raw material inlet, 350 g of water and Eleminol ES-70 (manufactured by Sanyo Chemical Industry Co., Ltd. as a surfactant) were used. 2g of activator was charged and the internal temperature was 75 ° C.
0.3 g of ammonium persulfate as a radical polymerization initiator and sodium bisulfite of 0.0 as a reducing agent.
After adding 5 g, n-butyl acrylate 110
g, methyl methacrylate 66 g, 2-hydroxyethyl acrylate 20 g and acrylic acid 4 g were added dropwise over 2 hours.

After the dropping, in order to reduce the residual monomer, 0.2 g of t-butylhydroxyperoxide as a free radical generator and L (+)-as a reducing agent.
0.1 g of ascorbic acid was added, and the mixture was aged at 80 ° C. for 2 hours.

The obtained emulsion was cooled to 25 ° C., and 2.5 g of 25% ammonia water was added as a neutralizing agent while continuing stirring to give a milky white aqueous adhesive having a pH of 7.8 and a solid content of 36.1% by weight. An agent composition was obtained.

The glass transition temperature and average particle size of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined in the same manner as in Example 1. . Table 1 shows the results.

Next, as the physical properties of the obtained water-based adhesive composition, coating properties and mechanical stability were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 5 In a 1 liter flask equipped with a stirrer, a reflux condenser and a raw material inlet, 450 g of water and Eleminol ES-70 as a surfactant (manufactured by Sanyo Kasei Co., Ltd., anionic interface) 10g of activator was charged and the internal temperature was adjusted to 75
0.3 g of ammonium persulfate as a radical polymerization initiator and sodium bisulfite as a reducing agent of 0.
After adding 05 g, n-butyl acrylate 110
g, 66 g of methyl methacrylate, 4 g of 2-hydroxyethyl acrylate and 4 g of acrylic acid were added dropwise over 2 hours.

After the dropping, in order to reduce the residual monomer, 0.2 g of t-butylhydroxyperoxide as a free radical generator and L (+)-as a reducing agent.
0.1 g of ascorbic acid was added, and the mixture was aged at 80 ° C. for 2 hours.

The obtained emulsion was cooled to 25 ° C., 2.5 g of 25% ammonia water was added as a neutralizing agent while continuing stirring, and a milky white aqueous adhesive having a pH of 7.2 and a solid content of 32.4% by weight was added. The composition was obtained.

The glass transition temperature and average particle size of the resin particles contained in the obtained aqueous adhesive composition, and the viscosity and thixotropic index of the obtained aqueous adhesive composition were examined in the same manner as in Example 1. . Table 1 shows the results.

Next, as the physical properties of the obtained aqueous adhesive composition, coating properties and mechanical stability were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 6 In a 1 liter flask equipped with a stirrer, a reflux condenser and a raw material inlet, 600 g of water and Eleminol ES-70 as a surfactant (manufactured by Sanyo Chemical Industry Co., Ltd., anionic interface) were used. 10g of activator was charged and the internal temperature was adjusted to 75
0.3 g of ammonium persulfate as a radical polymerization initiator and sodium bisulfite as a reducing agent of 0.
After adding 05 g, n-butyl acrylate 110
g, 66 g of methyl methacrylate, 100 g of 2-hydroxyethyl acrylate and 4 g of acrylic acid were added dropwise over 2 hours at such a rate that the total amount was added dropwise. Was observed, and when about 75% was dropped, stirring became impossible, so the polymerization was stopped.

[0114]

[Table 1]

From the results shown in Table 1, Examples 1 to 3 were obtained.
In comparison with Comparative Examples 1 to 5, the water-based adhesive compositions obtained in Examples 1 to 3 use resin particles having an average particle diameter of 100 nm or less, and 0.8 to 1. It can be seen that by having a thixotropic index of 2, it is excellent in both coating property represented by cissing and leveling and mechanical stability.

Examples 4 to 6 and Comparative Examples 7 to 11 The water-based adhesive compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 5 had a solid content of 30% by weight. Adjusted with water. The types of the aqueous adhesive composition used are shown in Table 2.

Next, to 100 parts by weight of each aqueous adhesive composition, 6 parts by weight of an aqueous emulsion of bisphenol A type epoxy resin (solid content 55% by weight) and 0.6 parts by weight of adipic dihydrazide were added, and the mixture was sufficiently added. After stirring, an aqueous adhesive composition containing an epoxy resin was obtained.

The physical properties of the obtained aqueous adhesive composition are as follows:
The dry laminating property and print laminating property were evaluated based on the following methods. Table 2 shows the results.

(C) Dry Lamination Property The obtained water-based adhesive composition was used as an automatic film applicator (manufactured by Yasuda Seiki Seisakusho, No.
542-AB) and a coating speed of 10 m / min. , Weight No. 2, bar coater No. Under the conditions of 7, a biaxially oriented polypropylene film having a thickness of 30 μm (hereinafter referred to as an OPP film) as a base film, a thickness of 12 μm
Polyethylene terephthalate film (hereinafter PET
It is applied to the corona discharge treated surface of a biaxially stretched nylon film having a thickness of 20 μm (hereinafter referred to as NYL film).

Next, each base film is preliminarily 70
After drying with a hot air dryer adjusted to ℃, a non-stretched polypropylene film (hereinafter referred to as a CPP film) having a thickness of 30 μm as a sealant film, a thickness of 3
0 μm linear low-density polyethylene film (hereinafter LL
DPE film) or a 20 μm thick aluminum-deposited unstretched polypropylene film (hereinafter VM-).
CPP film) is placed on the coated surface and is directly pressed by a thermocompression bonding roll. At this time, the temperature of the thermocompression bonding roll is 60 ° C. and the pressure is 200 kg / cm ² . Then, it is left to stand in a thermostatic chamber at 40 ° C. for 24 hours.

The dry laminate thus obtained was cut into a piece having a width of 15 mm to prepare a sample.
Austrain (produced by Yasuda Seiki Co., Ltd., No. 216 YZ50-) in an atmosphere of ℃ and relative humidity of 65%
I-T) and a speed of 300 mm / min. The T-shaped peel strength is measured with and evaluated according to the following evaluation criteria.

(Evaluation Criteria) A: Peel strength is 200 g / 15 mm width or more B: Peel strength is 100 g / 15 mm width or more, 200 g /
Less than 15 mm width C: Peel strength less than 100 g / 15 mm width

(D) Print Laminating Property The obtained water-based adhesive composition was used as an automatic film applicator (No.
542-AB) and a coating speed of 10 m / min. , Weight No. 2, bar coater No. Under the conditions of No. 12, it is applied to the corona discharge treated surface of an OPP film having a thickness of 20 μm.

Next, the OPP film was dried for about 10 seconds in a hot air dryer whose temperature was adjusted to 70 ° C., and the coated surface of the water-based adhesive composition and the printed surface of the printing paper were heat-compressed. Apply heat and pressure with a roll. At this time, the temperature of the thermocompression bonding roll is set to 60 ° C., and the pressure is set to 200 kg / c.
and m ^2.

Next, using the obtained print laminate, the tunneling resistance was examined, and after leaving it at room temperature for 48 hours, glossiness, adhesiveness and ink discoloration were examined. These measuring methods are as follows. The results are shown in Table 2.

Tunneling resistance Kraft paper printed as printing paper (basis weight 81 g /
m ² ), a print laminate with a temperature of 50
After being left for 24 hours in an atmosphere of 90 ° C. and 90% relative humidity, the print laminate is visually observed and evaluated based on the following evaluation criteria.

(Evaluation Criteria) A: No abnormalities are observed in the OPP film. B: Slightly floating on the OPP film and wrinkles are observed. C: Floats, wrinkles and the like are observed over the entire OPP film.

Gloss Art paper printed as printing paper (basis weight 128 g /
The print laminate in which m ² ) is used is visually observed and evaluated based on the following evaluation criteria.

(Evaluation Criteria) A: The gloss of the printing paper is improved as compared with that before lamination. B: The gloss of the printing paper is comparable to that before lamination. C: The gloss of the printing paper is lower than that before lamination.

Adhesive Coated cardboard printed as printing paper (basis weight 170 g
/ M ² ), a print laminate cut into 15 mm width was cut, and the obtained sample was autostrained (Yasuda Seiki Seisakusho Co., Ltd. No. 216 YZ in an atmosphere of a temperature of 20 ° C. and a relative humidity of 65%). -50-IT) and a speed of 300 mm / min. 180 ° peeling is performed, and the peeled state is visually evaluated.

(Evaluation Criteria) A: Ink is transferred to the entire surface of the OPP film, or a part of the printing paper is destroyed. B: Ink is transferred thinly or partially on the entire surface of the OPP film. C: Only a small part of the OPP film or no ink was transferred.

Ink discoloration A print laminate using a high-quality paper (basis weight: 88 g / m ² ) printed with a rhodamine dye and an alkali blue dye as a printing paper was used in an atmosphere at a temperature of 50 ° C. and a relative humidity of 90%. After left inside for 3 days, the change of the color tone of the printed part (dye) is visually observed.

(Evaluation Criteria) A: No change in color tone is observed. B: A slight change in color tone is observed. C: Clearly a change in color tone is observed.

[0134]

[Table 2]

From the results shown in Table 2, since the dry laminates obtained by using the aqueous adhesive compositions obtained in Examples 4 to 6 all exhibit a strong adhesive force,
It is understood that such an aqueous adhesive composition can be suitably used for dry laminating various films.

The water-based adhesive compositions obtained in Examples 4 to 6 all exhibit good print laminating properties. Among them, the water-based adhesive composition obtained in Example 6, in which 4-hydroxybutyl acrylate is used as a polymerization component, has any of tunneling resistance, glossiness, adhesiveness, and ink discoloration resistance. Since it is excellent, it can be used particularly preferably in the present invention.

[0137]

The water-based adhesive composition of the present invention has excellent coatability and mechanical stability. Therefore, for example, when a transparent resin film is laminated on a paper product, it is coated with good workability. Can be engineered.

Among them, the water-based adhesive composition of the present invention containing an epoxy resin is excellent in dry laminating property and print laminating property, so that it is suitably used for a laminate requiring high adhesive strength. be able to.

Claims (4)

[Claims] 1. A resin composition having a glass transition temperature of −30 to 10 ° C., an average particle diameter of 100 nm or less, a viscosity at 25 ° C. of 500 mPa · s or less, and a thixotropic index of 0.8. The water-based adhesive composition is characterized in that 2. A resin particle obtained by emulsion polymerization of a polymerization component containing a hydroxyl group-containing unsaturated monomer having a glass transition temperature of 0 ° C. or less when the resin particle is a homopolymer. The water-based adhesive composition described. 3. The water-based adhesive composition according to claim 2, wherein the hydroxyl group-containing unsaturated monomer having a glass transition temperature of 0 ° C. or less when formed into a homopolymer is 4-hydroxybutyl acrylate. 4. The water-based adhesive composition according to claim 1, which contains an epoxy resin containing two or more epoxy groups in the molecule.