JPS6328949B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in acrylic aqueous emulsion adhesives, and more particularly to a one-component acrylic aqueous emulsion adhesive composition containing polyglycidylamine as a crosslinking agent. Acrylic water-based emulsion adhesives are used as pressure-sensitive adhesives in the production of adhesive tapes, labels, or sheets, or as adhesives for bonding synthetic resins, wood, etc. together, or laminating films, papers, etc. Widely used as an agent.
Acrylic water-based emulsion adhesives can be roughly divided into one-component type and two-component type. Although the former has the advantage of being easier to use than the latter,
Since performance such as moisture resistance and heat resistance is generally inferior, two-component products are usually used for applications that require higher performance. The two-component acrylic water-based emulsion adhesive is
An aqueous emulsion obtained by copolymerizing acrylic ester with a small amount of α,β-unsaturated carboxylic acid,
It is an adhesive that is used in combination with a crosslinking agent such as polyisocyanate, polyepoxide, or polyglycidylamine, and because this type of adhesive contains a crosslinking agent, it is naturally difficult to use conventional adhesives. Demonstrates performance superior to liquid adhesives. However, two-component adhesives have the disadvantage that the pot life is relatively short because the crosslinking reaction begins when the crosslinking agent is mixed with the aqueous emulsion of the acrylic copolymer. In view of the advantages and disadvantages of conventional acrylic water-based emulsion adhesives as listed above, the present inventors have developed a one-component acrylic water-based emulsion adhesive, despite the fact that it contains a crosslinking agent. As a result of repeated research to develop a polyglycidylamine agent, we discovered that polyglycidylamine, which functions as a crosslinking agent, is dissolved in a hydrophobic organic solvent and/or plasticizer along with a tackifier that is inert to polyglycidylamine. If the resulting solution is dispersed in water in the form of small droplets, the polyglycidylamine is protected by a tackifier, so it will not react with water and lose its crosslinking ability, and this aqueous emulsion can be mixed with acrylics. Even if the polymer is mixed with an aqueous emulsion, a crosslinking reaction will not occur unless the water as a dispersion medium evaporates. It was discovered that the adhesive can be handled in exactly the same way as a one-component adhesive. Therefore, the one-component acrylic aqueous emulsion adhesive composition according to the present invention is a monomer mixture containing 50 wt% or more of an acrylic acid alkyl ester and 0.1 to 15 wt% of an α,β-unsaturated carboxylic acid. of,
An aqueous emulsion (A) obtained by emulsion polymerization and an aqueous emulsion (B) of a solution in which polyglycidylamine and a tackifier inert to polyglycidylamine are dissolved in a hydrophobic organic solvent and/or plasticizer. ). The aqueous emulsion (A) is a monomer mixture containing an acrylic acid alkyl ester and an α,β-unsaturated carboxylic acid as essential components, and optionally containing other copolymerizable vinyl monomers. It is prepared by emulsion polymerization in a conventional manner, and the monomer mixture contains 50 wt% of acrylic acid alkyl ester.
Above, 0.1 to 15wt% α,β-unsaturated carboxylic acid
must contain. If the amount of acrylic acid ester is less than 50wt%, the adhesion and adhesive strength will decrease, and if the amount of α,β-unsaturated carboxylic acid is less than 15wt%
This is because the adhesive strength decreases if the amount exceeds this value. The weight average molecular weight of the acrylic copolymer obtained by emulsion polymerization is preferably 10,000 or more, particularly 100,000 to 1,000,000 from the viewpoint of performance. Examples of acrylic acid alkyl esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate,
C ₁ to C ₁₂ exemplified by lauryl acrylate etc.
Preference is given to using acrylic acid alkyl esters having an alkyl group of . As the α,β-unsaturated carboxylic acid, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, etc. can be used. Other copolymerizable vinyl monomers that may be used as necessary include methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate,
Examples include acrylamide, N-methylol acrylamide, vinyl acetate, vinyl propionate, styrene, acrylonitrile, 2-hydroxy methacrylate, ethylene glycol dimethacrylate, and the like. Aqueous emulsion (B) is produced by dissolving polyglycidylamine and a tackifier inert to polyglycidylamine in a hydrophobic organic solvent and/or plasticizer, and then adding this solution to water in the coexistence of a surfactant. It is prepared by emulsifying and dispersing. As the polyglycidylamine, compounds having two or more epoxy groups and one or more tertiary nitrogen atoms in the molecule are used, and specifically, N/N-diglycidylaniline, N/N-diglycidyltoluidine, m-N・N-diglycidylaminophenyl glycidyl ether, triglycidyl isocyanurate, N・N・N′・N′-tetraglycidylethylenediamine, N・N・N′・N′-tetraglycidylaminodiphenylmethane, N・N・N'・
N'-tetraglycidyl-m-xylylene diamine is a typical example of the polyglycidylamine used in the present invention. The tackifier is preferably a hydrophobic one that does not contain a functional group such as a carboxyl group or an amino group that reacts with polyglycidylamine, and preferably has a softening point of about 70 to 150°C. Specifically, for example, petroleum-based hydrocarbon resins, terpene resins, and modified products thereof can be used as the tackifier. As the hydrophobic organic solvent, aromatic hydrocarbons such as toluene and xylene, and aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane are usually used. Typical hydrophobic plasticizers include dioctyl phthalate, dibutyl phthalate, dioctyl adipate, and terpene plasticizers. In addition, "hydrophobic" in relation to organic solvents and plasticizers refers to the solubility of water at 20℃.
This means 0.1wt% or less. When preparing the aqueous emulsion (B) of the present invention, the relationship between the amount of polyglycidylamine used and that of the tackifier is extremely important, especially when the amount of tackifier used is insufficient relative to the polyglycidylamine. However, since the polyglycidylamine cannot be sufficiently protected from water, the one-component adhesive which is the object of the present invention cannot be obtained. Therefore, when preparing the aqueous emulsion (B), it is possible to use 4 parts by weight or more of the tackifier per 1 part by weight of polyglycidylamine. The amount of hydrophobic organic solvent or plasticizer to be used can be selected arbitrarily, but in general, the amount of hydrophobic organic solvent or plasticizer is about 0.2 to 2 parts by weight per 1 part by weight of the total amount of polyglycidylamine and tackifier. It is practical to use. The mixing ratio of the aqueous emulsion (A) and (B) is 0.0001 to 0.5 equivalent per equivalent of carboxyl group contained in the acrylic copolymer in the aqueous emulsion (A);
Preferably, the proportion is such that 0.001 to 0.1 equivalent of epoxy groups can be supplied by the polyglycidylamine in the aqueous emulsion (B). The one-component acrylic water-based emulsion adhesive composition of the present invention comprises the above-mentioned water-based emulsions (A) and (B).
Unlike conventional one-component water-based emulsion adhesives, it contains a crosslinking agent, but the crosslinking agent is protected by a tackifier, so it is easy to store during storage. There is no loss of crosslinking ability. Incidentally, the one-component adhesive composition of the present invention shows no change in quality even after being stored at 40° C. for 6 months, and exhibits the same performance as at the time of preparation. In addition, because the one-component adhesive composition of the present invention contains a crosslinking agent, it has moisture resistance and heat resistance comparable to conventional two-component acrylic water-based emulsion adhesives. It can be widely used not only as a pressure sensitive adhesive but also as an ordinary adhesive. Examples will be explained below. Examples 1 to 3 and Comparative Examples 1 to 3 A Method for producing acrylic copolymer emulsion Sodium lauryl sulfate 1 part
(Hereafter shown in parts by weight) 50 parts of ion-exchanged water and 0.2 parts of potassium persulfate were placed in a reactor and heated to 75°C while flowing nitrogen gas.
The temperature was raised to 100 mL, and the next monomer emulsion was added dropwise over 3 hours. Emulgen 930 (product of Kao Soap Co., Ltd.) 2 parts Ion-exchanged water 49 parts Butyl acrylate 50 parts 2-ethylhexyl acrylate 47 parts Acrylic acid 3 parts t-dodecyl mercaptan 0.1 part After dropping, keep the temperature at 75℃ for 3 hours Hold to complete the reaction. After cooling to room temperature, add ammonia water to adjust the pH to 7.0-7.5, and reduce the non-volatile content to 50%.
% of acrylic copolymer emulsion (A) is obtained. B. Method for producing emulsion containing polyglycidylamine Toluene 50 parts FTR-6100 (Mitsui Petrochemicals Co., Ltd. product) 95 parts N・N-glycidylaniline 5 parts were dissolved and mixed Emulgen 931 (Kao Soap Co., Ltd. product) 2 100 parts of ion-exchanged water to obtain a polyglycidylamine-containing emulsion (B). Mix an appropriate amount of (B) with (A), apply it to a 25μm polyester film so that the dry coating thickness is 25μm, dry at 100℃ for 2 minutes, cover with release paper, and leave at room temperature for a certain period of time. The following performance was measured as a pressure sensitive adhesive. Adhesive strength Based on the adhesive strength of JIS Z-0237-1980 (180 degree peeling method). Holding force According to the holding force of JIS Z-0237-1980, the load is 1 kg, and the falling time of the load or the displacement distance after 60 minutes is measured at 40°C. Tatsu JIS Z-0237-1980 Tatsu (ball rolling method)
Measured at a tilt angle of 30 degrees. Moisture-resistance retention Retention and similar reagents at 30°C relative humidity
Measured at 85% atmosphere. Heat-resistant holding power The same test as holding power was measured in an atmosphere of 80°C. The performance is shown in Table 1.

[Adhesion method]

Base Wood Adhesive 30x foamed polyethylene (10mm thick) Application Brush 150g/ ^m2 wet onto wood Dry 20 minutes at 20℃ and RH65% Pressure Bonding 3 times with a 2Kg/5cm rubber roller Curing 20 minutes after bonding ℃ Leave in RH65% atmosphere for 2 days [Performance measurement] Normal adhesive strength After curing, 180 degree peel strength is 50
Measured at the speed of mm/min. Water resistant adhesive strength After curing, immerse in water at 20℃ for 7 days,
Measured immediately after removal in the same way as normal adhesive strength. Heat-resistant adhesive strength After curing, leave in an atmosphere at 60°C for 20 minutes, then measure at 60°C in the same way as normal adhesive strength. The performance is shown in Table 2.

【table】

【table】

Claims (1)

[Claims] 1. A one-component aqueous emulsion adhesive composition obtained by mixing the following aqueous emulsions (A) and (B). (A) Contains 50wt% or more of acrylic acid alkyl ester and 0.1 to 0.1% or more of α,β-unsaturated carboxylic acid.
Aqueous emulsion (B) obtained by emulsion polymerization of a monomer mixture containing 15 wt%. Polyglycidylamine and a tackifier inert to polyglycidylamine are dissolved in a hydrophobic organic solvent and/or plasticizer. Aqueous emulsion of solution.