JPH0352981A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, consisting essentially of an acrylic resin prepared by polymerizing an alkyl (meth)acrylate monomer in the presence of a water-soluble composition, excellent in initial adhesive force and water resistance, good in coating and quick drying properties with a high-speed machine and useful as an adhesive for environmental application. CONSTITUTION:The objective composition consisting essentially of an acrylic resin prepared by polymerizing (A) 45-99.99wt.% alkyl (meth)acrylate having a 1-12C alkyl group and (B) 0-50wt.% other copolymerizable monomers in the presence of (C) 0.01-5wt.% water-soluble composition of a homopolymer of an amine, ammonia or monovalent metal salt with styrenesulfonic acid or a copolymer of styrene, alpha-methylstyrene, vinyltoluene or an alkyl (meth)acrylate monomer at a copolymerization ratio thereof without exceeding 20wt.%.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention has excellent permeability into the interior of each adherend when used as a wet adhesive for pasting materials such as paper, wood, rubber, fibers, and plastics. It exhibits diffusive properties and has great effects on adhesive strength, etc. For example, the anchoring properties of the surface material are improved, and because it dries quickly, the initial adhesion is good and the final strength is significantly improved. When used as an adhesive, it can produce labels and sheets with excellent water and moisture resistance. As described above, we have developed an acrylic copolymer emulsion type adhesive composition that can be used in a wide range of applications.

(Prior art) Conventionally, adhesives for paper and paper, paper and plastic film, paper and cloth, cloth and plastic, etc. have been made using vinyl acetate, vinyl acetate-ethylene, vinyl acetate-(meth)acrylic, acrylic, acrylic-styrene, etc. (Co)polymers are widely used industrially because they have advantages in terms of adhesive strength and price. However, it cannot satisfy the requirements for water resistance, quick drying, and initial adhesive strength. In particular, if the surface of the adhesive is difficult to absorb moisture, drying will be slow and it will take time for the initial strength to increase. This results in defects in repulsion resistance and adhesive peeling.

In addition, for adhesive labels that require water resistance,
We are taking measures to improve this by reducing the particle size of the emulsion and minimizing the amount of surfactant used. If this method is used, the emulsion will be difficult to generate, resulting in very poor storage stability and mechanical stability. Emulsion-type adhesives and pressure-sensitive adhesives (hereinafter referred to as adhesives/adhesives) have many physical properties required for machines that are becoming faster and faster, in addition to adhesive strength, cohesive strength, and anchoring properties, but each has drawbacks. I couldn't be more satisfied.

(Problem to be solved by the invention) The present invention solves the conventional drawbacks as described above.
The objective is to provide adhesives that have improved water resistance, quick drying properties, and initial adhesive strength without degrading storage stability or mechanical stability. Conventional surfactants and protective colloids do not offer water resistance, quick drying, initial adhesive strength,
It is difficult to provide stability at the same time.

For example, reducing the amount of surfactant to improve water resistance will result in poor stability, and increasing the amount of surfactant will result in poor drying properties.
Adhesion strength also deteriorates. Furthermore, if a large amount of protective colloid is added in the form of an aqueous solution during or after the polymerization reaction, the initial adhesion will improve, but the drying properties and water resistance will deteriorate. According to the present invention, an adhesive composition having excellent physical properties as described above can be produced by simply using a small amount of a surfactant.

(Means for Solving the Problems) The present invention provides 45 to 99.99% by weight of (meth)acrylic acid alkyl ester monomers having an alkyl group of 1 to 12 carbon atoms.
and other copolymerizable monomers O to 50% by weight, homopolymers of amines, ammonia or monovalent metal salts of styrene sulfonic acid or styrene, α-methylstyrene, vinyltoluene or alkyl (meth)acrylates. An adhesive composition containing an acrylic resin as a main component, which is polymerized in the presence of 0.01 to 5% by weight of a water-soluble composition of a copolymer in which the copolymerization ratio of the ester monomer does not exceed 20f[jl%]. be.

In addition, in the adhesive composition, the alkyl group has 4 to 4 carbon atoms.
It is desirable to use 45 to 99.99% by weight of the (meth)acrylic acid alkyl ester monomer of l2. Examples of the alkyl (meth)acrylate monomer having an alkyl group having 1 to 12 carbon atoms include methyl (meth)acrylate,
Examples include ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and other copolymerizable monomers. Examples include (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, acrylamide, N-methylolacrylamide, vinyl acetate, acrylonitrile, styrene, hydroxyethyl (meth)acrylate, hydroxybutylic acrylate, glycidyl (meth) Examples include acrylate, dialkylaminoalkylene (meth)acrylate, alkoxyvinylsilane, etc. Also, examples of (meth)acrylic acid alkyl ester monomers copolymerized with styrene sulfonic acid salts include methyl (meth)acrylate (meth)ethyl acrylate , n-butyl (meth)acrylate, isobutyl (meth)acrylate, (meth)
Examples include 2-ethylhexyl acrylate, isononyl (meth)acrylate, and lauryl (meth)acrylate.

As styrene sulfonate, in the case of amine salt, triethylamine, diethylamine, triethanolamine,
Examples include diethanolamic acid and stearylamine, and examples of monovalent metal salts include sodium and potassium.

Although the present invention uses (meth)acrylic acid alkyl ester as the main component, it is better for the adhesive composition to have a high glass transition point, and preferably the alkyl group has 1 to 1 carbon atoms.
The main component is (meth)acrylic acid ester up to the 4th position, and other copolymerizable monomers such as vinyl acetate, styrene,
Dibutyl maleate, acrylic acid, maleic acid, acrylamide, etc. are used as appropriate. In addition, in the adhesive composition, an alkyl group having a carbon number of 4 to 12 and a low glass transition point is used. The amount used is 45 to 99.9% by weight based on the total monomer components. 4
If it is less than 6% by weight, the characteristics of the present invention cannot be achieved. The homopolymer or copolymer of styrene sulfonate used in the present invention can be used in a range of 0.01 to 5% by weight, but the desired effect cannot be obtained if 0.01% by weight is used. ．． Moreover, if it exceeds 5% by weight, it is not preferable because it causes a decrease in adhesive strength and a decrease in tackiness and adhesive strength of the adhesive. Homopolymer of styrene sulfonate or styrene,
The copolymerization ratio of α-methylstyrene, vinyltoluene or (meth)acrylic acid alkyl ester monomer is 20
The preparation of copolymers not exceeding % by weight is carried out in aqueous solution according to customary methods. However, in the case of a copolymer, the copolymerization ratio of styrene, α-methylstyrene, vinyltoluene, or (meth)acrylic acid alkyl ester monomer is 20! If it exceeds ji%, a good copolymer aqueous solution cannot be obtained.

The surfactant used in the present invention is not particularly limited, and commonly used anionic or nonionic surfactants may be used alone or in combination. Furthermore, it is effective to use a copolymerizable emulsifier in applications where contamination of the adherend surface must be strictly controlled, such as in removable adhesive applications. Depending on the adherend, styrene-butadiene copolymer latex, natural rubber latex, nitrile-butadiene copolymer latex, etc. may be added to the emulsion thus obtained in order to increase adhesive strength. Further, when the adherend is olefin-based, adding an aqueous dispersion of petroleum resin or natural resin is beneficial for improving strength.

It is not clear why the styrene sulfonate homopolymer or copolymer used in the present invention exhibits such excellent performance, but there is a special particle formation process during the polymerization reaction. Depending on the composition, the particles may be smaller than those of ordinary surfactant or protective colloid emulsions, but they also have good stability, film-forming properties, and water resistance. The effects of the present invention will be described in more detail with reference to Examples below. In the Examples, parts and percentages are based on weight. Example 1 50 parts of ion-exchanged water, 1.0 part of nonionic surfactant Nonion NS-230 (Borioxyethylene alkyl phenyl ether type manufactured by NOF ■), anionic surfactant Neogen T [Daiichi Kogyo Seiyaku ■] Add 0.5 part of sodium dodecylbenzenesulfonate] and dissolve with stirring. Next, add 20 parts of n-butyl acrylate, 35 parts of methyl acrylate, 40 parts of methyl methacrylate, 4 parts of styrene, and 1 part of acrylic acid. A monomer mixture, 3 parts of a homopolymer of sodium styrene sulfonate, and 0.2 part of ammonium persulfate as a polymerization initiator were mixed and emulsified to prepare a monomer η and a liquid solution.

Next, 18 parts of ion-exchanged water was charged into a reaction vessel, the mixture was filled with nitrogen, and heated while stirring. When the internal temperature reached 80°C, 0.2 parts of ammonium persulfate was added to emulsify the monomer prepared in advance. The polymerization reaction is started by sequentially adding the liquid, and the dropwise reaction continues for 2.5 hours.

After completion of the dropwise addition, stirring was continued for 1.5 hours at the same temperature. Thereafter, the mixture was cooled and 0.3 part of aqueous ammonia was added to obtain an emulsion with an evaporation residue of 60%, a viscosity of 2,500 cp, and a pH of 6.5.

Using this composition, an adhesion test between high-quality paper and aluminum foil paper was conducted.

Example 2 The same polymerization reaction as in Example 1 was carried out in Example 1, except that 3 parts of a sodium styrene sulfonate/methyl methacrylate copolymer containing 5% methyl methacrylate was used instead of the sodium styrene sulfonate homopolymer. After adjustment, the evaporation residue was 59.8% and the viscosity was 2,550 cps. P
An emulsion of H6.5 was obtained. A test was conducted in the same manner as in Example 1 using this composition.

Comparative Example 1 In Example 1, except for the sodium styrene sulfonate homopolymer, the same polymerization reaction and adjustment as in Example 1 were carried out to obtain an evaporation residue of 59.6% and a viscosity of 2,500 cpSPHI.
An emulsion of No. 5 was obtained.

Adhesion Test Method The adhesive compositions of Examples 1 and 2 and Comparative Example 1 were coated on high-quality paper at a rate of approximately 5 g/T+1'' in terms of evaporation residue, and evaluated using the following method. Aluminum foil was fixed to a glass tube, and high-quality paper coated with adhesive was immediately bonded to the aluminum foil, and the extent to which the aluminum foil peeled off within 10 seconds was examined.

Items that do not peel off (○), items that peel off slightly (△),
Those with large peeling were marked as (×).

Final Adhesive Strength After bonding high-quality paper and aluminum foil paper together and observing the adhesive strength after 24 hours, those with complete paper tearing rate (○), those with 50% paper tearing rate (Δ), and those with no paper tearing ×) And so.

After 24 hours of bonding the water-resistant high-quality paper and the aluminum foil paper together, they were immersed in room temperature water for 3 hours, then taken out, the water was wiped off, and the adhesive strength was evaluated in the same way as the final adhesive strength.

Example 3 50 parts of ion-exchanged water, 1.0 part of nonionic surfactant Nucor 804 (polyoxyethylene alkylphenol ether type manufactured by Nippon Nyukazai ■), and anionic copolymerizable emulsifier Eleminol JS-2 (Sanyo Kasei 1tllU)
Add 2.0 parts of and stir to dissolve. Next, 80 parts of 2-ethylhexyl acrylate and 10 parts of ethyl acrylate were added to this.
1 part, 9 parts of methyl methacrylate, 1.0 part of acrylic acid, 1.0 part of sodium styrene sulfonate homopolymer, and 0.2 part of ammonium persulfate were mixed and emulsified to prepare a monomer emulsion. Next, 18 parts of ion-exchanged water was charged into a reaction vessel, the mixture was filled with nitrogen, and heated while stirring. When the internal temperature reached 80°C, 0.2 parts of ammonium persulfate was added to emulsify the monomer prepared in advance. The liquid was added sequentially to start the polymerization reaction, and the dropwise reaction continued for 2.5 hours. After the addition is complete, stir at the same temperature for 1.5 hours. After that, 1.0 part of the thickener Cybinol AZ-1 (acrylic type manufactured by Saiden Chemical ■) and 0.5 part of ammonia water were added, and the evaporation residue was 60.2%, the viscosity was 11,000 cp,
An emulsion with pH 8.0 was obtained.

Adhesive performance tests were conducted using this composition. Example 4 5 parts of natural rubber latex (in terms of evaporation residue) and 5 parts of aqueous dispersion of hydrogenated rosin ester a (in terms of evaporation residue) were blended into 100 parts of the emulsion of Example 3, resulting in an evaporation residue of 59%,
Viscosity 10,000 cp. An emulsion with a pH of 7.8 was obtained. A test was conducted in the same manner as in Example 3 using this composition.

Comparative Example 2 Polymerization and adjustment were carried out in the same manner as in Example 3 except that the sodium styrene sulfonate homopolymer was removed, resulting in an evaporation residue of 59.8%, viscosity of 8,500 cp, and pH of 8.0
An emulsion was obtained. A test was conducted in the same manner as in Example 3 using this composition.
Adhesive Performance Test The adhesive performance test was conducted in accordance with JIS Z-0237-1980. Adhesive is transferred using high-quality paper <55>
The coating amount was 22g/IC evaporation residue). A polished stainless steel plate was used as the object, and the water resistance test was conducted by attaching the sample to a glass plate and conducting the same test as the final adhesive strength of the adhesive. (Effects of the Invention) When the pressure-sensitive adhesive composition according to the present invention is used for the purpose of improving initial adhesive strength and water resistance, good results can be obtained.

In addition, because the emulsion has excellent stability, it can be applied using high-speed machines and can be used as an adhesive for on-site construction by taking advantage of its quick drying properties.

Claims (6)

[Claims] (1) 45 to 99.99% by weight of a (meth)acrylic acid alkyl ester monomer having 1 to 12 carbon atoms and 0 to 50% by weight of other copolymerizable monomers, such as styrene sulfonic acid amine, ammonia or Water-soluble composition of a homopolymer of a monovalent metal salt or a copolymer in which the copolymerization ratio of styrene, α-methylstyrene, vinyltoluene, or (meth)acrylic acid alkyl ester monomer does not exceed 20% by weight 0.01 An adhesive composition whose main component is an acrylic resin polymerized in the presence of ~5% by weight. (2) The pressure-sensitive adhesive composition according to claim 1, which is an alkyl (meth)acrylic acid ester in which the alkyl group has 4 to 12 carbon atoms. (3) The adhesive composition according to claims 1 and 2, wherein the surfactant used in producing the adhesive composition is a copolymerizable emulsifier. (4) The adhesive according to claim 1 or claim 2, wherein any one of styrene-butadiene copolymer latex, natural rubber latex, and nitrile-butadiene copolymer latex is added alone or in a mixture to the adhesive composition. agent composition. (5) The adhesive composition according to Claims 1 and 2, wherein an aqueous dispersion containing petroleum resin or natural resin as a main component is added to the adhesive composition. (6) The adhesive composition according to Claims 1 and 2, further comprising a crosslinking agent capable of reacting with the functional component of the adhesive composition.