JPS6281469A - Two-pack type acrylic adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having excellent adhesive strength in a normal, heated or thermally aged state, by mixing two kinds of specified compositions and an ethylene/acrylic rubber having an unsaturated group introduced therein. CONSTITUTION:One or more (meth)acrylic esters (a) are mixed with 0.1-10wt% organic peroxide (b) which generate radicals to polymerize component (a), thus giving a composition (A). At least one of component (a) is mixed with 0.05-10wt% reducing agent (c) (e.g., a polyamine) which accelerates the decomposition of component (b) to generate radicals, thus giving a composition (B). An ethylene/acrylic rubber of formula I (wherein X, Y and Z are each an integer) is reacted with an unsaturated aziridine compound of formula II (wherein R1 is H or methyl; R2-5 are each H or a 1-4C alkyl) at 40-80 deg.C for 2-5hr, thus giving an ethylene/acrylic rubber having an unsaturated group introduced therein (C) of formula III. Then, component C is added to at least one of components A and B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radically polymerizable two-component acrylic adhesive composition.

(Conventional technology) In recent years, epoxy adhesives and rubber adhesives have been used in the assembly and bonding process of speakers for light electrical appliances in order to streamline work, improve product performance, and require high reliability. Acrylic adhesives have become widely used. This is because acrylic adhesives have a shorter fixation time than epoxy adhesives, and because they are two-component non-mixable, they do not require adhesive mixing and can reduce adhesive loss. Since adhesives contain solvents in their components, it takes a considerable amount of time for the solvent to volatilize after the adhesive is applied and to solidify, and if the solvent does not volatilize sufficiently, the adhesive strength may decrease. This is because it had

Acrylic adhesives have superior oil resistance, chemical resistance, water resistance, and weather resistance compared to other resin adhesives, so they are widely used for industrial purposes other than those listed above.
On the other hand, it also has the disadvantage of poor impact strength and peel strength, and its range of use has been limited to certain fields. Recently, it has been found that adding various elastomers (e.g., unvulcanized rubber, acrylic rubber, shrimp glolhydrin rubber, etc.) to such acrylic adhesive compositions can improve the impact strength and peel strength of the adhesive. This discovery greatly contributed to expanding the range of uses for adhesives such as mechanical parts.

(The good luck point that the invention seeks to solve) However, with the diversification of approximation demands, adhesives are now required to have better adhesive performance and adhesive performance even under harsh conditions. In this sense, even the acrylic adhesives mentioned above are still insufficient, and further improvements have been desired.

The present invention was made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a novel adhesive composition that has excellent adhesive performance under normal conditions and can maintain excellent adhesive performance even when the adherend is exposed to high temperatures. be.

(Means for solving the problem of black hair) The gist of the present invention to achieve the above object is to use one or more types of acrylic esters or methacrylic esters and an organic compound that generates radicals and polymerizes the esters described in 11. Composition (A) containing peroxide and tri'' as components
ζ, acrylic ester or methacrylic ester, and a reducing agent that promotes the decomposition of the organic peroxide and generates radicals. , a two-component acrylic adhesive composition characterized in that at least one of the compositions (A) and (B) contains ethylene acrylic rubber into which an unsaturated group has been introduced.

The acrylic ester or methacrylic ester that is the main resin component of adhesive compositions (A) and (B) is collectively referred to as (meth)acrylic ester, and includes methyl (meth)acrylate, (meth)ethyl acrylate, propyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, benzyl (meth)acrylate, Mono(meth)acrylates such as phenoxyethyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate, polyester(meth)acrylate, polyether(meth)acrylate, epoxy(meth)acrylate, urethane(meth)acrylate, ( Oligo(meth)acrylates such as meth)acrylic modified polymers have been adopted;
One species or a combination of several species may be used as appropriate.

The organic peroxide in composition (A) is selected from hydroperoxide, alkyl peroxide, diacyl peroxide, and ketone peroxide, and more specifically, cumene hydroperoxide, t
-Butyl hydroperoxide, vermenthane hydroperoxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, dicumyl peroxide, benzoyl peroxide and the like are preferably employed. The blending ratio of these organic peroxides to the composition (A) is 0.1 to 10 weight 1+t% (hereinafter all percentages are expressed as weight ff1), preferably 0.1 to 5%. That is,
If it exceeds 10%, the storage stability of the composition (A) described in 1-1 may deteriorate and it may harden before use;
This is because if it is less than -, it will not contribute sufficiently to the polymerization and curing reaction of the (meth)acrylic acid ester described in -.

The reducing agent proposed in composition (B) is one that promotes the decomposition of organic peroxides to generate radicals and acts as a polymerization accelerator, such as thiourea compounds, metal chelate compounds,
Metal soaps, tertiary amines, polyamines, mercaptans, etc. or other known promoters can be used. These accelerators are not limited to one type, but two or more types can also be used.

The amount of reducing agent used is 0.05 to 10%, preferably 0.1 to 6%; if it is too little, the polymerization rate will be slow, and if it is too much, the adhesive strength will be reduced.

In addition, the above compositions (A) and (R) include hydroquinone,
It is possible to contain quinone-type stabilizers such as benzoquinone, or other known stabilizers, antioxidants, fillers, pigments, paraffin to improve surface hardening properties, and various additive components. They will be adopted as appropriate depending on the situation.

The gist of the present invention is that at least one of the compositions (A) and (B) contains an ethylene acrylic rubber into which an unsaturated group has been introduced as a nidistomer. That is, by adding this unsaturated group-introduced ethylene acrylic rubber to an acrylic adhesive composition, the adhesive strength under normal conditions and the strength after heating and heat aging increases, making it suitable as an adhesive. The range of uses will be expanded.

It has been found that ethylene acrylic rubber having unsaturated groups introduced into the molecule can be produced by the following method. That is, first, ethylene acrylic rubber is dissolved in the (meth)acrylic monomer, and an unsaturated aziridine compound is dissolved in 4
An unsaturated group is introduced into the carboxyl group of the ethylene acrylic rubber by dropping a predetermined amount dropwise in the range of 0°C to 80°C and mixing and stirring at the same temperature for 2 to 5 hours. The reaction is as shown in the following formula.

(Here, x, y, z and Q are integers, R1 is hydrogen or a methyl group, and R2 to R are selected from the group consisting of hydrogen and an alkyl group having 1 to 4 carbon atoms. , which may be the same or different, respectively.) Unsaturated aziridine compounds that can be used include 2-(+-aziridinyl)ethyl methacrylate, 2-[-(2-methylaziridinyl)]ethyl acrylate, 2-[+-
(2-methylaziridinyl)]ethyl methacrylate,
2-(1-(2,2-dimethylaziridinyl)]ethyl acrylate, 2-(1-(2-ethylaziridinyl)
]Ethyl acrylate, 2-(1-(2-ethylaziridinyl))ethyl methacrylate, trimethylolpropane-morph-no β-aziridinylpropionate diacrylate,
These include tetramethylolmethane-mono-β-aziridinylpropionate diacrylate, and one or more of these can be used.

The unsaturated aziridine compound is preferably used in an amount of 0.01 to 2 equivalents of aziridine group per equivalent of carboxyl group in the ethylene acrylic rubber.

If the amount is less than 0.01 equivalent, the adhesive performance will deteriorate, and if more than 2 equivalents are added, unreacted unsaturated aziridine will only increase, which is wasteful.

(Function) In order to bond a pair of adherends using the above composition, the composition (A) is applied to one joint surface, and the composition (B) is applied to the other joint surface.
) are applied respectively, and when both are overlapped, composition (B)
The reducing agent in the composition generates radicals, decomposes the organic peroxide in the composition (A), accelerates curing, and converts both groups of acids (A) and (B).
The (meth)acrylic esters therein fuse with each other and polymerize and harden to form a resin, thereby firmly adhering both adherends. In addition, in the present invention, since at least one of the compositions (A) and (B) contains ethylene acrylic rubber into which an unsaturated group has been introduced, not only the monomer but also the polymer undergoes radical polymerization to form a graft polymer. Rather, the strength increases when heated and after heat aging.

(Example) The present invention will be further explained in detail with reference to Examples below.

[1] Synthesis of ethylene acrylic rubber with unsaturated groups; Methyl methacrylate 1. 0 parts by weight (the same applies hereinafter) and 40 parts of ethylene acrylic rubber (Baymac N-123, manufactured by DuPont) were charged, and the temperature was adjusted to 60° C. with stirring to completely dissolve Baymac N-123. Next, 2-(1-aziridinyl)ethyl methacrylate was added dropwise in the amount shown in Table 1 over 10 minutes from the dropping funnel, kept at the same temperature for an additional period of time, and cooled to form a composite σ having the composition shown in Table 1. ) to ■ were obtained. However, ■ is one in which 2-(1-aziridinyl)ethyl methacrylate is not added, and is used as a comparative example below. By titrating these carboxylic acid groups, the proportion of free carboxylic acid groups in the ethylene acrylic rubber converted to unsaturated groups was determined and is shown in Table 2.

However, the numbers are by weight Table I [2] Preparation of adhesive base solution;
, F1 part was charged and heated and stirred at r'r O''C for 1 hour to obtain an adhesive base solution.

[Preparation of 3-adhesive silk composition (A >(R); Next]
- Divide the base solution into two parts, add 3 parts of cumene hydroperoxide to one part and mix to make solution A, and add 1.5 parts of monobenzoylthiourea to the other part and mix. It was made into a liquid.

Table 3 shows the composition of these adhesive compositions.

16th generation However, *1 represents cumene hydroperoxide and *2 represents monobenzoylthiourea.

[4] Measurement of adhesive strength; =11- (a) Test piece adhesion method Apply the various compositions (A) of [3] to one joint surface of two iron adherends, and apply the various compositions (A) of [3] to the other joint surface. The above composition (B) was applied to the substrate, and both were superimposed and adhered.

(b) Measurement of tensile shear strength The test pieces were adhered as described in 4-, left at room temperature for 24 hours, and then measured at 20°C in accordance with JIS K-6850.

(c) Measurement of peel strength After leaving the test piece adhered in the same manner as described above at room temperature for 24 hours, it was measured at 20°C in accordance with JIS K6854.

(d) Impact strength measurement After leaving the test piece glued in the same manner as above at room temperature for 24 hours,
Measured at ℃ in accordance with JIS [6855.

(e) Heating strength measurement After leaving the test piece glued in the same manner as above at room temperature for 24 hours,
The sample was placed in an oven at 120°C or 120°C for 30 minutes, and the tensile shear strength and peel strength were measured at that temperature.

(f) 150°C heat aging test After leaving the test piece adhered in the same manner as above at room temperature for 24 hours,
The sample was kept in an oven at 0°C for 72 hours, returned to 20°C, and subjected to the above-mentioned tensile shear strength, peel strength, and impact strength measurements.

The results of (b) to (e) are shown in Table 4, and the results of (f) are shown in Table 5.

(Hereinafter referred to as 1 to 1) As shown in Section 1-1, the two-component acrylic adhesive composition of the present invention is composed of ethylene with unsaturated J introduced into either one of compositions (A) and (B). Since the acrylic rubber hits each other, not only the monomer but also the polymer undergoes radical polymerization due to the action of the rubber, resulting in a graft polymer that exhibits excellent adhesive strength not only under normal conditions but also during heat or heat aging.Acrylic adhesive This will greatly contribute to expanding the range of applications for these agents.

-And more-

Claims (1)

[Scope of Claims] 1. A composition (A) containing as main components one or more acrylic esters or methacrylic esters and an organic peroxide that generates radicals and polymerizes the esters; A composition (B) mainly comprising one or more acrylic esters or methacrylic esters and a reducing agent that promotes the decomposition of the organic peroxide and generates radicals, (A) (B)
A two-component acrylic adhesive composition comprising ethylene acrylic rubber having an unsaturated group introduced into at least one of the two. 2. The composition according to claim 1, wherein the ethylene acrylic rubber into which unsaturated groups have been introduced is obtained by a reaction between an unsaturated aziridine compound and ethylene acrylic rubber.