JPH0222111B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a radically polymerizable two-component acrylic adhesive composition. (Prior technology) In recent years, acrylic has been used in the assembly and bonding process of speaker parts for light electrical appliances in place of epoxy adhesives and rubber adhesives in order to streamline work, improve product performance, and require high reliability. 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 drawback 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 (for example, unvulcanized rubber, acrylic rubber, epichlorohydrin rubber, etc.) to such acrylic adhesive compositions improves the impact strength and peel strength of the adhesive. is,
This greatly contributed to expanding the range of uses for adhesives such as mechanical parts. (Problems to be Solved by the Invention) 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 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. . (Means for Solving the Problems) The gist of the present invention for achieving the above object is to polymerize one or more acrylic esters or methacrylic esters and an organic polymer that generates radicals to polymerize the esters. oxide, one or more acrylic esters or methacrylic esters, and a reducing agent that promotes the decomposition of the organic peroxide to generate radicals. A two-component acrylic adhesive composition, characterized in that it contains an ethylene acrylic rubber into which an unsaturated group has been introduced into at least one of the compositions A and B. The acrylic esters or methacrylic esters that are the main resin components of adhesive compositions A and B are collectively referred to as (meth)acrylic esters, and include methyl (meth)acrylate and (meth)acrylic ester. ethyl acid, propyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate,
Mono(meth)acrylates such as benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate;
Oligo (meth) acrylates such as polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and (meth) acrylic modified polymers are used, and one or more of these are used. are used in appropriate combinations. 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. oxide, permenthane 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 Composition A is 0.1 to 10% by weight (all percentages hereinafter are by weight), preferably 0.1 to 5%. That is,
If it exceeds 10%, the storage stability of the composition A 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 ester. In addition, the reducing agent contained in Composition B acts as a polymerization accelerator by promoting the decomposition of organic peroxides and generating radicals. 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.
What is the amount of reducing agent used? It is 0.05 to 10%, preferably 0.1 to 6%, and the lower the amount, the slower the polymerization rate.
If it is too large, the adhesive strength will decrease. others,
The above compositions A and B contain quinone type stabilizers such as hydroquinone and benzoquinone, or other known stabilizers, antioxidants, fillers, pigments, paraffin to improve surface hardening properties, and various additive components. It is possible to do so, and it may be adopted as appropriate depending on the purpose. 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 an elastomer. 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 under heat and after heat aging increases, and the adhesive becomes stronger. The scope of its use 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, a predetermined amount of an unsaturated aziridine compound is added dropwise in the range of 40°C to 80°C, and the mixture is stirred at the same temperature for 2 to 5 hours to form ethylene acrylic rubber. An unsaturated group is introduced into the carboxyl group of. The reaction is as shown in the following formula. (Here, X, Y, Z and l are integers, R ₁ is hydrogen or a methyl group, and R ₂ to _{R 5} are selected from the group consisting of hydrogen and an alkyl group having 1 to 4 carbon atoms. (They may be the same or different.) Usable unsaturated aziridine compounds include 2-
(1-aziridinyl)ethyl methacrylate, 2
-[-(2-methylaziridinyl)]ethyl acrylate, 2-[1-(2-methylaziridinyl)]
Ethyl methacrylate, 2-[1-(2,2-dimethylaziridinyl)]ethyl acrylate, 2-
[1-(2-ethylaziridinyl)]ethyl acrylate, 2-[1-(2-ethylaziridinyl)]
Ethyl methacrylate, trimethylolpropane-mono-β-aziridinylpropionate diacrylate, tetramethylolmethane-mono-β-
These include aziridinyl propionate diacrylate, and one or more of these can be used. The amount of unsaturated aziridine compound used is 1 carboxyl group in ethylene acrylic rubber.
The amount of aziridine group is preferably 0.01 to 2 equivalents. 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) To bond a pair of adherends using the above composition, apply composition A to one joint surface and composition B to the other joint surface, and then overlap them.
The reducing agent in composition B generates radicals, and composition A
The organic peroxide in the composition is decomposed to promote curing, and the (meth)acrylic acid esters in both compositions A and B fuse with each other and are polymerized and cured to form a resin, thereby firmly adhering both adherends. In the present invention, composition A,
Because at least one of 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, resulting in strength not only under normal conditions but also under heat and after heat aging. Becomes large. (Example) The present invention will be further explained in detail using Examples below. [1] Synthesis of ethylene acrylic rubber with unsaturated groups; 100 parts of methyl methacrylate (parts by weight,
), 40 parts of ethylene acrylic rubber (manufactured by Dupont, Beymatsu N-123) and stirred.
The temperature was adjusted to 60°C to completely dissolve Bay Mackerel N-123. Next, the amount of 2-(1-aziridinyl)ethyl methacrylate shown in Table 1 was added dropwise from the dropping funnel over 10 minutes, and the mixture was further kept at the same temperature for 3 hours.
After cooling, a composite having the composition shown in Table 1 was obtained. However, 2-(1-aziridinyl)ethyl methacrylate was not added, and this is the comparative example below. By titrating these carboxylic acid groups, the ratio of free carboxylic acid groups of the ethylene acrylic rubber converted to unsaturated groups was determined, and the results are shown in Table 2.

[Table] However, the numbers are parts by weight.

[Table] [2] Preparation of adhesive base solution; Add 15 parts of 2-hydroxyethyl methacrylate and 0.5 parts of paraffin wax to 100 parts of the above composite or solution, and stir at 60°C for 1 hour to prepare the adhesive base. A solution was obtained. [3] Preparation of adhesive compositions A and B; Next, the above base solution was divided into two parts, and 3 parts of cumene hydroperoxide was added to one part for 50 parts of the base solution.
1.5 parts of monobenzoylthiourea was added to the other and mixed to prepare liquid B.
Table 3 shows the composition of these adhesive compositions.

[Table] C and *2 indicate monobenzoylthiourea, respectively.
[4] Measurement of adhesive strength; (a) Test piece adhesion method: Apply various compositions A of [3] to one joint surface of two iron adherends, and apply the above composition B to the other joint surface. was applied, and the two were overlapped and bonded. (b) Measurement of tensile shear strength The test pieces were adhered as described above, left to stand at room temperature for 24 hours, and then measured at 20°C in accordance with JIS K-6850. (c) Measurement of peel strength The test pieces adhered in the same manner as above were left at room temperature for 24 hours, and then 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 for 24 hours,
Measured in accordance with JIS K6855. (e) Measurement of strength when heated The test pieces bonded in the same manner as above were left at room temperature for 24 hours, then placed in an oven at 60°C or 120°C for 30 minutes.
The tensile shear strength and peel strength were measured at that temperature. (f) 150°C heat aging test After leaving the bonded test piece as above at room temperature for 24 hours, it was kept in an oven at 150°C for 72 hours, and then returned to 20°C to measure the tensile shear strength, peel strength, and impact strength described above. provided. The results of (b) to (e) are shown in Table 4, and the results of (f) are shown in Table 5.

【table】

【table】

[Table] (Effects of the Invention) As mentioned above, the two-component acrylic adhesive composition of the present invention contains ethylene acrylic rubber into which an unsaturated group has been introduced into either one of compositions A and B.
Due to the action of this rubber, not only the monomer but also the polymer undergoes radical polymerization to form a graft polymer, which exhibits excellent adhesive strength not only under normal conditions but also during heat or heat aging, expanding the range of applications for acrylic adhesives. The contribution is extremely large.

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 to polymerize the esters, and an acrylic ester. Or a composition B whose main components are one or more methacrylic acid esters 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. 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.