JPH0147508B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to improvements in adhesives.

Reactive adhesives that substantially do not contain a solvent and are cured by polymerization of monomer components to strongly bond various types of adherends are known. For example, it is a two-component adhesive, where the first component consists of an acrylic monomer or methacrylic monomer and peroxide or hydroperoxide, and the second component is a polymerization of the acrylic or methacrylic monomer at room temperature. It consists of an activator that initiates.

Here, the activator is preferably one that can provide sufficient adhesive strength even in a non-stoichiometric amount relative to the monomer.

U.S. Pat. No. 3,890,407 describes a sulfur-containing composition selected from the group consisting of chlorosulfonated polyethylene and a mixture of sulfonyl chloride and chlorinated polyethylene, and a sulfur-containing composition selected from the group consisting of acrylic monomers and methacrylic monomers. Adhesive compositions are shown comprising a solution of at least one polymerizable monomer as well as a free radical generator.

However, although this type of adhesive composition provides excellent bonding, it requires improvement in terms of odor and toxicity to the human body. An important factor in the actual use of adhesives is that they have excellent adhesive performance (adhesion speed and adhesive strength).
Issues such as the odor of adhesives and their toxicity to the human body are equally important. No matter how good the adhesive performance is, if it has a strong odor or is harmful, it will be difficult to use.

The present inventors investigated this problem from various angles and found that if at least one monomer selected from tetrahydrofurfuryl acrylate or tetrahydrofurfuryl methacrylate is used, it will reduce odor and be harmful to the human body. It was found that the adhesive curing speed and adhesive strength were excellent.

Although many monomers are described as specific examples of polymerizable monomers in U.S. Patent No. 3,890,407, particularly preferred monomers are lower alkyl acrylates and methacrylates, and specific examples include methyl methacrylate and ethyl methacrylate. , n-butyl methacrylate, 2-ethylhexyl methacrylate, etc., among which methyl methacrylate, ethyl methacrylate and n-
Butyl methacrylate has a strong odor and is quite harmful to the human body. Although 2-ethylhexyl methacrylate has a relatively weak odor, it still has an odor characteristic of acrylic monomers, and adhesives made from 2-ethylhexyl methacrylate alone are unsatisfactory in terms of adhesion speed and adhesive strength.

On the other hand, the odor of the tetrahydrofurfuryl methacrylate and tetrahydrofurfuryl acrylate of the present invention is almost odorless, less harmful, and extremely useful in practical terms. Another advantage of this monomer is its high adhesion speed and high adhesive strength.

Monomers that can be used in addition to the tetrahydrofurfuryl methacrylate and acrylate of the present invention include methacrylic acid or acrylic acid, which have the effect of improving strength, ethylene glycol dimethacrylate, and trimethacrylate, which have the effect of improving heat resistance. Di- or tri-(meth)acrylates such as methylolpropane trimethacrylate, as well as other general (meth)acrylate monomers, can be used as long as the usage rate is small and the odor when glued is not affected too much. It is.
It goes without saying that the amount of these monomers used within this range does not impair adhesive performance.

The chlorosulfonated polyethylene used in the present invention is made from polyethylene containing 25 to 75% by weight of chlorine and 3 to 160 mmol of sulfonyl chloride moieties per 100 g of polymer and having a melting coefficient of 4 to 500. . Suitable sulfonyl chlorides include, for example, toluenesulfonyl chloride, diphenyl ether-4,4'-disulfonyl chloride, and the like. The ratio of chlorosulfonated polyethylene to polymerizable monomer is from 50 to 500 parts by weight of monomer per 100 parts by weight of polymer. The same applies to chlorinated polyethylene.

The present invention also uses organic peroxides and organic hydroperoxides as free radical generating agents. The amount of organic peroxide is from 0.01 to 10 parts by weight of the total composition. A stabilizer is also added to improve storage stability. The most preferred stabilizer is 2,6-
Di-t-butyl-4-methylphenol.
The preferred amount of stabilizer is 0.01 to 10 parts by weight of the total composition.

The activator compounds used in the invention are, for example, tertiary amines (e.g. N,N-dimethylaniline, N,N-diisopropyl-p-toluidine) or condensation products of aldehydes with primary or secondary amines. (For example, condensation products of butyraldehyde and aniline or butylamine; exemplary compounds include DuPont Activators 808 and 833.

According to the present invention, an accelerator is used in conjunction with an activator to increase the speed of adhesive curing. Suitable promoters include oxidizing compounds of transition metals. For example, copper naphthenate, cobalt naphthenate,
Included are complexes of iron naphthenate, nickel naphthenate, or acetylacetone with iron, copper, cobalt, or vanadium.

Example 1 Tetrahydrofurfuryl methacrylate 120
g, chlorosulfonated polyethylene Note 1) 60g,
Methacrylic acid 15g, ethylene glycol dimethacrylate 3g, Qyumene hydroperoxide 1.0g, 2,6-di-t-butyl-4-methylphenol 0.6g Note 1) Contains 43% chlorine and 11% sulfur, Mooney viscosity 30 chlorosulfonated polyethylene.

A uniform adhesive composition was prepared. This product had only a slight sour odor from methacrylic acid, and had almost no unpleasant odor.

AA−150 cold rolled steel plate with dimensions of 100×25×1.6mm
A thin layer of Dupont Activator 808 was applied to one of the specimens, which had been polished with sandpaper and degreased with a 1:1 mixture of acetone and toluene, and the adhesive composition of this example was applied to the other specimen. and both sides 2~
They were rubbed together three times, overlapped so that the adhesive area was 25 x 12.5 mm, and pressed together with a force of about 1 Kgf, and the tensile shear strength was measured after 5 minutes and 24 hours. Tensile shear strength after 5 minutes: 136Kg/cm ² , tensile shear strength after 24 hours: 258Kg/cm ² .

The storage stability of this adhesive composition was tested as follows. Approximately 8g of the sample is placed in a 10ml glass bottle, the bottle is tightly capped, and the bottle is placed in an oven at 80°C to measure the time until gelation occurs. The gelation time of this composition is approximately 15
It was found that it has sufficient stability over time.

Example 2 Tetrahydrofurfuryl methacrylate 120
g, chlorosulfonated polyethylene Note 2) 55
g, methacrylic acid 20g, ethylene glycol dimethacrylate 3g, kyumene hydroperoxide 1.0g, 2,6-di-t-butyl-4
-Methylphenol 0.8g.

Note 2) Contains 29% chlorine and 1.4% sulfur, and uses chlorosulfonated polyethylene with a Mooney viscosity of 30.

A uniform adhesive composition was prepared. Similar to Example 1, the odor was extremely mild.

A primer containing 0.05% copper in activator 808 was applied thinly to one side of a steel plate test piece similar to that in Example 1, and the adhesive composition of Example 2 was applied to the other side and then pressed. The tensile shear strength was measured after 5 minutes and 24 hours.

Tensile shear strength after 5 minutes: 168 Kg/cm ² Tensile shear strength after 24 hours: 265 Kg/cm ² As in Example 1, the time until gelation was measured in an oven at 80°C revealed that it was extremely stable after about 20 hours. was good.

Comparative example Methyl methacrylate instead of 120g of tetrahydrofurfuryl methacrylate in Example 1
The same adhesive composition as in Example 1 was prepared except that 120 g was used. This product had a very strong odor characteristic of methyl methacrylate. As in Example 1, using DuPont Activator 808, the tensile shear strength was measured after 5 minutes and 24 hours.

Tensile shear strength after 5 minutes: 35 Kg/cm ² Tensile shear strength after 24 hours: 229 Kg/cm ² The gelation time at 80° C. was 10 hours. The product using methyl methacrylate had a strong odor and was weak in strength after 5 minutes.

Example 3 The same as Example 1 except that 75 g of tetrahydrofurfuryl methacrylate and 45 g of 2-ethylhexyl methacrylate were used instead of 120 g of tetrahydrofurfuryl methacrylate in Example 1.
The same adhesive composition was prepared. The odor of this product was almost similar to that of the adhesive composition of Example 1, and there was almost no unpleasant odor.

As in Example 1, the tensile shear strength was measured after 5 minutes and 24 hours using DuPont Activator 808.

The tensile shear strength after 5 minutes was 128 Kg/cm ^{2 and} the tensile shear strength after 24 hours was 261 Kg/cm ² and the gelation time at 80° C. was 15 hours, indicating sufficient stability.

Claims (1)

[Scope of Claims] 1 (1) at least one monomer selected from tetrahydrofurfuryl methacrylate or tetrahydrofurfuryl acrylate; (2) at least one monomer selected from the group consisting of acrylic monomers or methacrylic monomers; An adhesive composition comprising: (3) chlorosulfonated polyethylene or a mixture of sulfonyl chloride and chlorinated polyethylene (4) peroxide (5) a stabilizer.