JPS6329909B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyurethane adhesives, more specifically,
The present invention relates to an organic solution type polyurethane adhesive that exhibits excellent adhesive strength particularly when at least one of the adherends is a polyvinyl chloride sheet, film, or foam. Conventionally, solution-type polyurethane adhesives have excellent flexibility and plasticizer resistance, so they are used for molded products such as polyvinyl chloride sheets, films, and foams that contain a large amount of plasticizers, and other plastic materials. It is used in many fields as a universal adhesive because it bonds well with materials such as wood, metal, etc. However, it has been desired to develop an adhesive that can prevent adhesive deterioration due to plasticizers migrating from the adherend to the adhesive interface, has excellent heat resistance, and has improved performance. Therefore, the present inventors conducted intensive research in order to develop an adhesive that would be less affected by the plasticizer contained in the adherend, and found that they dissolved thermoplastic polyester urethane rubber in an organic solvent, and added it to the adhesive for acrylic resin. We discovered that a polyurethane adhesive with excellent plasticizer adhesion resistance could be obtained by grafting a monomer and blending the main adhesive component with chlorinated rubber and an isocyanate compound as a crosslinking agent. The invention was completed. That is, the present invention provides (a) a thermoplastic polyester urethane rubber (hereinafter referred to as urethane rubber) grafted with at least one member selected from the group of acrylic acid, acrylic ester, methacrylic acid, and methacrylic ester (hereinafter referred to as urethane rubber). (referred to as graft rubber), (b) chlorinated rubber, and (c) an isocyanate compound as a crosslinking agent. The object of the present invention is to improve the adhesive strength after heat aging and the adhesive strength at heat even when applied to the case where at least one of the adherends is a polyvinyl chloride sheet, film, or foam containing a large amount of plasticizer. Our goal is to provide superior polyurethane adhesives. The urethane rubber used in the present invention is an elastomer having a urethane bond in its molecular chain, and usually includes polybasic acids (terephthalic acid, isophthalic acid, phthalic acid, succinic acid, adipic acid, azelaic acid,
sebacic acid, etc.) and dihydric alcohols (ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol,
Polyethylene glycol, propylene glycol, etc.) are subjected to a condensation reaction, and the resulting saturated polyester resin with terminal hydroxyl groups is combined with active hydrogen groups and diisocyanate compounds (tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, etc.). , cyclohexylmethane diisocyanate, etc.) in approximately equivalent amounts. Such urethane rubber can be prepared using suitable organic solvents, such as ester-based (ethyl acetate, butyl acetate, etc.), ketone-based (methyl ethyl ketone, cyclohexanone, acetone, etc.), aromatic (toluene, xylene, benzene, etc.), chlorine-based (triclene, chloride, etc.). methylene, etc.)
It dissolves easily in etc. In the present invention, a monomer to be grafted onto the urethane rubber (hereinafter referred to as a graft monomer)
is acrylic acid, acrylic ester (e.g. methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate, 2-ethoxyethyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, acrylic 2-hydroxyethyl acid, 2-hydroxypropyl acrylate, 1,4
-butanediol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, etc.), methacrylic acid and methacrylic acid esters (e.g. methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-methacrylate)
Butyl, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, lauryl-tridecyl methacrylate, tridecyl methacrylate, cetyl-stearyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, methacrylic acid 2-hydroxyethyl,
2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, etc.), and at least one member selected from these groups. to be made available for use. Particularly preferred are functional ones having at least one of a hydroxyl group, a cyano group, a glycidyl group, and an amino group. In addition to such monomers, acrylamide, acrylonitrile, acrolein, vinyl acetate, styrene, N-methylolacrylamide, vinylpyridine, maleic anhydride, vinylpyrrolidone, butadiene, etc. can also be used in combination. The above-mentioned graft rubber, which is component (a) in the present invention, is produced by grafting a graft monomer to urethane rubber by a conventional method. For example, after dissolving the urethane rubber in an organic solvent,
Add and mix a radical-generating polymerization initiator (benzoyl peroxide, azobisisobutyronitrile, kyumene hydroperoxide, t-butyl hydroperoxide, potassium persulfate, ammonium persulfate, etc.) and a graft monomer, ~
Graft polymerization is carried out under heating at 100°C under reflux for at least 1 hour, preferably 2 to 4 hours. In such grafting, the ratio of the urethane rubber to the graft monomer is 10 to 70 parts of the graft monomer per 100 parts (by weight, same hereinafter) of the urethane rubber, of which at least 10 to 30 parts should be grafted. is desirable. If the amount of monomer to be grafted is less than 10 parts, the adhesion will not be improved, and if it exceeds 30 parts, the solution viscosity may increase or gelation may occur during polymerization. The above polymerization initiator is usually used in an amount of 0.3 to 1.0 parts per 100 parts of urethane rubber, but if it is too little, excessive polymerization speed and time will be required, while if it is too much, the polymerization will be good.
Solution viscosity may increase and gelation may occur. The graft rubber thus obtained is used in a 5-30% solution of the organic solvent. In the present invention, the chlorinated rubber, which is the component (b), refers to natural rubber or synthetic rubber that is reacted with chlorine. CR-5”,
"CR-10", "CR-20", "CR-40", "CR-40"
"CR-90" and "CR-150" are commercially available, as well as synthetic rubber products such as chlorinated polyethylene and chlorinated polypropylene, which are made by chlorinating polyethylene and polypropylene, and chlorinated polypropylene made from polyvinyl chloride and chlorinated polyethylene. Examples include vinyl chloride. These chlorinated rubbers dissolve well in aromatic, ester, and ketone organic solvents. The amount of chlorinated rubber used is usually the graft rubber of component (a).
The amount may be selected within the range of 0.5 to 20 copies per 100 copies. It should be noted that even if the chlorinated rubber is added to non-grafted urethane rubber, it has almost no effect, but if it is added to a grafted rubber like the one of the present invention, the plasticity in the adherend will increase, although the reason is unknown. It was observed that the migration of the agent to the adhesive interface was reduced and the hot adhesive strength was significantly improved. In the present invention, the crosslinking agent for component (c) is an isocyanate compound that is used as a crosslinking agent for ordinary chloroprene solvent-based adhesives and urethane rubber adhesives, and has a high vapor pressure, low toxicity to the human body, and is easy to handle. For example, triphenylmethane triisocyanate (Bayer
Desmodur R, 20% methylene chloride solution),
Triisocyanate phenyl thiophosphate (Desmodur RF manufactured by Bayer, 20% methylene chloride solution), isocyanate compound obtained by adding trimethylolpropane to tolylene diisocyanate (Coronate L manufactured by Nippon Polyurethane Co., Ltd., 75% ethyl acetate solution), Examples include special grade MDI (Millionate MR manufactured by Nippon Polyurethane Co., Ltd.). In such isocyanate compounds, the active hydrogen group of the hydroxyl group in the molecular chain of the grafted rubber (a) component reacts with the isocyanate group, resulting in crosslinking, so it contributes to the improvement of adhesive strength. 3 to 50 parts per 100 parts of the graft rubber of component (a)
The selection should be made so that the The polyurethane adhesive according to the present invention is usually used as described above.
An adhesive main component consisting of component (a) and component (b), and (c)
It is put into practical use as a two-part organic solution with a crosslinking agent as a component. Applications include not only adhesion between at least one adherend, such as a polyvinyl chloride sheet, film, or foam, containing a large amount of plasticizer, and plastic materials, wood, or metal materials; It is also useful as an adhesive for laminating plastic films and the like, which is the main use of polyurethane adhesives. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Examples 1 to 5 Urethane rubber (Pandex T5205 manufactured by Dainippon Ink Industries, Ltd.) in the numbers shown in Table 1, graft monomers (MMA: methyl methacrylate, EA: ethyl acrylate, 2-HEMA: 2-methacrylic acid)
Hydroxyethyl, GA: glycidyl acrylate, AN: acrylonitrile), organic solvent (MEK: methyl ethyl ketone), and polymerization initiator (BPO: benzoyl peroxide) were weighed accurately in a glass container in advance, and the mixture was heated under reflux at 80°C for 3 hours. The main component of the adhesive is prepared by adding and dissolving chlorinated rubber into the resulting solution. A polyurethane adhesive is prepared by blending 20 parts of a crosslinking agent (Desmodur R) with 100 parts of the main component. Comparative Example 1 A polyurethane adhesive is prepared in the same manner as in Examples 1 to 5, except that no graft monomer is used and a non-grafted urethane rubber is used. Comparative Example 2 A polyurethane adhesive is prepared in the same manner as in Example 1 except that chlorinated rubber is not added. Test example: PVC sheet leather product (Orsia manufactured by Sunstar Giken Co., Ltd.) and ABS resin (Kane Ace manufactured by Kanebuchi Kagaku Co., Ltd.) made into strips of 20 mm width x 100 mm length. The adhesives of Examples 1 to 5 or Comparative Examples 1 to 2 are each applied to a resin plate at a rate of about 100 g/m ² , and after drying with a solvent, the resin plates are bonded together to prepare an adhesive test piece. After curing and curing this test piece for one day, the autograph determined the 180° peel adhesion strength and 110° peel strength.
The peel adhesion strength was measured in a heated atmosphere at ℃, and 100 g
A 24-hour creep test is performed under a load of The test results are shown in Table 1.

[Table] As is clear from the results in Table 1, in the thermal creep test, the influence of the plasticizer from the polyvinyl chloride product on the adherend should be large in reducing the adhesive strength. A dramatic improvement is observed in the examples compared to the comparative examples.

Claims (1)

[Scope of Claims] 1 (a) a thermoplastic polyester urethane rubber grafted with at least one member selected from the group of acrylic acid, acrylic ester, methacrylic acid, and methacrylic ester; (b) chlorinated rubber; (c) A polyurethane adhesive characterized in that it consists of an isocyanate compound as a crosslinking agent. 2. The polyurethane adhesive according to claim 1, wherein the acrylic ester or methacrylic ester includes a functional one having at least one of a hydroxyl group, a cyano group, a glycidyl group, and an amino group. 3. The polyurethane adhesive according to claim 1, which is an organic solution type.