JPS6214192B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an acrylic adhesive composition that is made into an acrylic adhesive by appropriately combining a radical initiator and a promoter. "(Meth)acrylic acid" or "(meth)acrylate" described in this specification collectively refers to acrylic acid and/or methacrylic acid, or acrylate and/or methacrylate, respectively. (Industrial application field) Liquid low-viscosity (meth)acrylate monomers and synthetic polymers are added to various epoxy (meth)acrylates derived from bifunctional epoxy compounds for epoxy resins, etc. It is already known that an acrylic adhesive can be produced by combining a radical initiator or an accelerator with a blended material. However, since such acrylic adhesives generally have high rigidity of the adhesive layer, they do not have sufficient peel adhesion strength or impact adhesion strength, and are not fully satisfactory as structural adhesives. In addition, bisphenol A is reacted with propylene oxide to elongate the chain, then reacted with epichlorohydrin to epoxidize it, and then reacted with (meth)acrylic acid to form a bifunctional epoxy with a double bond introduced at the end. It is already known to prepare an acrylic adhesive composition that cures by radical polymerization by using (meth)acrylate and blending it with a liquid low-viscosity (meth)acrylate monomer and a synthetic polymer. (Unexamined Japanese Patent Publication 1973-
Publication No. 21725). However, the adhesive using bifunctional epoxy (meth)acrylate obtained by chain elongation with propylene oxide described in the same publication has extremely low peel adhesive strength and impact adhesive strength (experiments shown in Table 3). (See No. 8). (Problems to be Solved by the Invention) The present invention provides that each component of the adhesive composition has good compatibility, and that either a radical initiator or a promoter is added, or both are not added. Even if the same composition is stored for a long time, there is no risk of separation of components, and if the composition is appropriately combined with a radical initiator and accelerator, it will harden quickly and be suitable for various materials. The object of the present invention is to provide an acrylic adhesive composition capable of providing an adhesive exhibiting excellent adhesive performance, particularly excellent peel adhesion strength and impact adhesive strength. In the acrylic adhesive composition of the present invention, (A) a β-methylepihalohydrin-derived bifunctional epoxy compound is reacted with a dibasic acid to elongate the chain, and further reacted with (meth)acrylic acid to polymerize the terminals. (B) A (meth)acrylate monomer other than the monomer described in (A) above, and (C) A synthetic high molecular weight polymer. This is a composition that is cured by radical polymerization and contains each of the following components. As mentioned above, the epoxy (meth)acrylate (A), which is the first component constituting the acrylic adhesive composition of the present invention, is a dibasic acid added to a β-methylepihalohydrin-derived bifunctional epoxy compound. is reacted to elongate the chain, and further reacted with (meth)acrylic acid to introduce a polymerizable double bond at the end. The raw material β-methylepihalohydrin-derived bifunctional epoxy compound can be prepared by converting β-methylepihalohydrin (e.g. β-methylepichlorohydrin) into bisphenol A, bisphenol F, hydrogenated bisphenol A, or hydrogenated bisphenol F. It is obtained by reacting with the like, and is itself known as a bifunctional epoxy compound for epoxy resins. Examples of the dibasic acid as a chain extender reacted with this β-epihalohydrin-derived bifunctional epoxy compound include succinic acid, adipic acid, azelaic acid, and sebacic acid. In the chain elongation reaction between a β-epihalohydrin-derived bifunctional epoxy compound and a dibasic acid, 0.5 to 2 mol of the dibasic acid is added to 2 mol of the same epoxy compound.
Preferably mixed at a ratio of about 1 mole, 100 to 200
The reaction proceeds easily by heating and stirring at a temperature of 130 to 180° C. for several hours to several tens of hours. After cooling the reaction product to an appropriate temperature, for example, 40 to 50°C, an appropriate amount of catalyst (for example, triethylamine, tri-n-butylamine, etc.) and 2 to 4 moles of (meth)acrylic acid are added thereto. In addition, the difunctional epoxy (meth)acrylate (A) used in the present invention can be obtained by stirring and reacting at a temperature of 40 to 60° C. for several hours to more than ten hours. Since the difunctional epoxy (meth)acrylate of the present invention has been chain-elongated with a dibasic acid, it is highly flexible, and the adhesive obtained using it has peel adhesion strength and impact adhesion. Becomes superior in strength. Furthermore, since the bifunctional epoxy (meth)acrylate of the present invention is derived from a β-methylepihalohydrin-derived bifunctional epoxy compound, it has a similar chain structure compared to, for example, an epihalohydrin-derived bifunctional epoxy compound. Compared to bifunctional epoxy (meth)acrylate obtained by elongation and reaction with (meth)acrylic acid, it has excellent compatibility with synthetic high molecular weight polymers. To this end, the adhesive composition of the present invention
Even if the product is stored for a long period of time with the addition of either a radical initiator or a promoter, or without the addition of both, there is no risk of separation of components over time. The bifunctional epoxy (meth)acrylate used in the present invention is, for example, bisphenol A/β-
An example of a bifunctional epoxy methacrylate obtained by reacting an epichlorohydrin type bifunctional epoxy compound with adipic acid as a chain extender and further reacting with methacrylic acid is as shown by the formula on the next page. There is (in the formula,
n represents a number from 0 to 13 as an average value, and m represents a number from 1 to 5 as an average value. ). In the present invention, difunctional epoxy (meth)
One type of acrylate (A) may be used, or two or more types may be used in combination as appropriate. The amount of bifunctional epoxy (meth)acrylate (A) is:
The amount is usually 5 to 50% by weight, preferably 10 to 30% by weight, based on the adhesive composition. If the blending ratio becomes too large, the crosslinking density will increase and flexibility will be lost. On the other hand, if the blending ratio is too small, the crosslinking density will be low, making it impossible to form a strong adhesive layer, resulting in low peel adhesive strength and impact adhesive strength. Various types of (meth)acrylate monomers (B) can be used as the second component in the acrylic adhesive composition of the present invention. For example, various acryl (meth)acrylates, hydroxyl group-containing (meth)acrylates, ether group-containing (meth)acrylates,
Acrylate, (meth)acrylate containing benzene ring or cyclohexyl ring, (meth)acrylate containing dicyclopentene ring, (meth)acrylate containing fluorine atom, (meth)acrylate containing sulfone group
Acrylate, (meth)acrylic acid amide, bornyl ring-containing methacrylate, polyfunctional (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, urethane (meth)acrylate, diene structure group-containing (meth)acrylate, etc. Furthermore, other (meth)acrylates can be used as long as they are liquid, low-viscosity (meth)acrylates that are compatible with the synthetic high molecular weight polymer (C). Specific examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate.
Acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, dodecyl ( Examples include meth) acrylate, cetyl (meth) acrylate, and stearyl (meth) acrylate. Examples of the hydroxyl group-containing (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Examples of the ether group-containing (meth)acrylates include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, and 2-methoxydiethylene glycol (meth)acrylate.
Acrylate, 2-methoxytetraethylene glycol (meth)acrylate, 2-methoxypolyethylene glycol (meth)acrylate, 2-
Examples include phenoxyethyl (meth)acrylate. Examples of the benzene ring- or cyclohexyl ring-containing (meth)acrylate include benzyl (meth)acrylate, methylbenzyl (meth)acrylate, and cyclohexyl (meth)acrylate. Examples of the dicyclopentene ring-containing (meth)acrylate include cyclopentenyl (meth)acrylate, 2-dicyclopentenyloxyethyl (meth)acrylate, and the like. Examples of the above-mentioned fluorine atom-containing (meth)acrylate include trifluoroethyl (meth)acrylate. Examples of the sulfone group-containing (meth)acrylate include 2-sulfoethyl (meth)acrylate. Examples of the above-mentioned (meth)acrylamide include (meth)acrylamide, N-methylol (meth)acrylamide, methoxymethyl (meth)acrylamide, butoxymethyl (meth)acrylamide, and the like. Examples of the bornyl ring-containing (meth)acrylate include isobornyl (meth)acrylate. Examples of the polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentenyl glycol di(meth)acrylate, tri- Methylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate,
Examples include tetramethylolmethanetetra(meth)acrylate, tris[2-(meth)acryloxyethylene]isocyanurate, and the like. As the (meth)acrylate monomer (B) in the present invention, one type thereof may be used, or two types thereof may be used.
More than one species may be used in combination as appropriate. The content of the liquid low viscosity (meth)acrylate monomer is usually 10 to 95% by weight, preferably 60 to 90% by weight, based on the adhesive composition. If the proportion of the (meth)acrylate monomer (B) is too small, the viscosity of the adhesive composition will become high, making it difficult to handle when used as an adhesive, while if it is too large, the adhesive properties such as adhesive strength will deteriorate. leading to a decrease in Various types of synthetic polymers (C) can be used as the third component in the acrylic adhesive composition of the present invention. Examples include diene rubber, acrylic rubber, urethane rubber, acrylic resin, ASA resin, ABS resin, MBS resin, vinyl chloride resin, chlorinated polyethylene, polyurethane resin, and polyester resin. Examples of the diene rubber include acrylonitrile/butadiene copolymer rubber (NBR), acrylonitrile/butadiene/other copolymerizable monomer copolymer rubber, chloroprene rubber (CR),
Chloroprene/other copolymerizable monomer copolymer rubber, styrene/butadiene copolymer rubber (SBR), styrene/butadiene/other copolymerizable monomer copolymer rubber, butyl rubber (BR), isoprene rubber (IB), liquid Polybutadiene, liquid
Examples include NBR. The above-mentioned acrylic rubber is a rubber-like polymer containing an acrylic acid alkyl ester as a constituent unit, and typical examples include butyl acrylate/acrylonitrile copolymer rubber,
Examples include ethyl acrylate/acrylonitrile copolymer rubber, ethyl acrylate/2-chloroethyl acrylate copolymer rubber, and the like. In addition to these two-component acrylic rubbers, there are also those copolymerized with acrylic acid, methacrylic acid, etc. as a third component, and these rubbers can also be used in the present invention. The above-mentioned urethane rubber is an elastic body having urethane bonds in its molecular structure, and includes, for example, those obtained by reacting various polyester polyols and polyether polyols with various isocyanate compounds. There are many types. In the present invention, one type of these synthetic polymers (C) may be used, or two or more types may be used in combination as appropriate. The amount of synthetic polymers used is as follows for the acrylic adhesive composition:
It is usually 2 to 60% by weight, preferably 5 to 40% by weight. The acrylic adhesive composition of the present invention can be prepared using various methods.
Usually difunctional epoxy (meth)acrylate (A)
, a liquid low viscosity (meth)acrylate monomer (B), and a synthetic high molecular weight polymer (C) in a predetermined ratio,
heating the mixture to a temperature of e.g. 50-80°C,
It is convenient to carry out the method of uniformly dissolving the synthetic high molecular weight polymer in the mixed liquid of the other two components by stirring. The acrylic adhesive composition of the present invention undergoes radical polymerization and hardens upon heating without using a radical initiator or accelerator, so it can be used as is as a one-component heat-curable adhesive. However, the compositions are generally desirable for use in various combinations of radical initiators and accelerators in various types of fast curing adhesives. The acrylic adhesive composition of the present invention is generally of three representative types: a two-component type, a primer type, and a direct addition type, depending on the combination of curing agents and accelerators. For the two-component type, the composition is divided into two parts, the radical initiator (curing agent) is added to one part, and the accelerator is added to the other part, and both parts are mixed together immediately before using the adhesive. Alternatively, both liquids may be applied separately to the adhesive surface, and the two liquids may be mixed or brought into contact with each other on the adhesive surface. For the primer type, a curing agent is mixed with the composition and the accelerator is dissolved in a volatile solvent, or an accelerator is mixed with the composition, the curing agent is dissolved in a volatile solvent, and both are applied to the adhesive surface. The liquids are applied separately and used. In addition, in the direct addition type, the curing agent and the accelerator are directly added to the composition and mixed immediately before the adhesive is used, and the adhesive is used within its usable life. Examples of the radical initiator (curing agent) used in combination with the acrylic adhesive composition of the present invention include diacyl peroxides such as benzoyl peroxide and acetyl peroxide; cumene hydroperoxide, t-butyl hydroperoxide, etc. Hydroperoxides such as oxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; dialkyl peroxides such as digmyl peroxide and di-t-butyl peroxide; peroxides such as t-butyl peroxyacetate; Oxyesters; and various other known radical initiators. Two or more types of radical initiators can also be used in combination. Examples of accelerators used in combination with the acrylic adhesive composition of the present invention include tertiary promoters such as N·N-dimethylaniline, N·N-dimethyl-p-toluidine, diisopropanol-p-toluidine, and triethylamine. Amines; polyamines such as diethylenetriamine, triethylenetetramine, and pentaethylenehexamine; thioureas such as thiourea, ethylenethiourea, benzoylthiourea, acetylthiourea, and tetramethylthiourea;
Known promoters include organic or inorganic acid salts of metals such as copper, cobalt, manganese, and vanadium; reducing organic compounds such as ascorbic acid and gallic acid; and other metal chelate compounds and mercaptans. Two or more of these promoters can also be used in combination. The amounts of the radical initiator and accelerator used in the adhesive composition of the present invention are the same as conventional ones, and the total amount of both relative to the adhesive is usually:
The amount is about 0.05 to 20% by weight, preferably about 0.1 to 10% by weight. If the amount used is too small, the polymerization and curing rate will be slow, and curing will take a long time. If the amount is too large, heat generation will be large, and the adhesive layer will contain air bubbles, resulting in a decrease in adhesive strength. The adhesive composition of the present invention may optionally contain p-
Quinone type stabilizers such as benzoquinone and hydroquinone, antioxidants, fillers, dyes, pigments and various other additives can be blended. (Effects of the invention, etc.) The acrylic adhesive composition of the present invention uses a bifunctional epoxy (meth)acrylate (A) derived from a β-methylepihalohydrin-derived bifunctional epoxy compound. Since this bifunctional epoxy (meth)acrylate (A) has excellent compatibility with synthetic high molecular weight polymers, it is necessary to add either a radical initiator or an accelerator, or both. There is no risk of separation of components over time even if the composition is stored without any oxidation. In addition, since this bifunctional epoxy (meth)acrylate (A) is chain-elongated with a dibasic acid and given flexibility, the adhesive prepared from this composition has adhesive strength, In particular, it has excellent peel adhesive strength and impact adhesive strength, and these adhesive strengths are even superior to those of room temperature curing epoxy adhesives (for general structural use). In addition, instead of component (A) of the present invention, a bifunctional epoxy (meth)acrylate obtained by chain-extending an epihalohydrin-derived bifunctional epoxy compound with a dibasic acid and then reacting it with (meth)acrylic acid. When an adhesive composition is prepared by blending a liquid low-viscosity (meth)acrylate monomer (B) and a synthetic high molecular weight polymer (C) with this, the bifunctional epoxy Due to the poor compatibility of (meth)acrylates with synthetic high molecular weight polymers, if the composition is stored without the addition of either an initiator or an accelerator, or both, the components (See Comparative Example 2 in Table 2). In addition, we used a bifunctional epoxy (meth)acrylate obtained by directly reacting a β-methylepyrlohydrin-derived bifunctional epoxy compound with (meth)acrylic acid without chain-extending it with dihydrochloric acid. When an adhesive composition is made by blending a liquid low-viscosity (meth)acrylate monomer (B) and a synthetic high molecular weight polymer (C), the adhesive using that composition is classified as Adhesive strength, especially peel adhesion strength and impact adhesion strength, is inferior to adhesives using the adhesive composition of the invention (Table 3
(See Experiment No. 1). (Examples, etc.) Hereinafter, the present invention will be further described in detail by giving epoxy compound production examples, epoxy (meth)acrylate production examples, examples, and comparative examples. Epoxy compound production example 1 342 g (1.5 mol) of bisphenol A and 1388 g (15 mol) of β-methylepichlorohydrin were heated to reflux at a temperature of 120°C with stirring, and 304 g (3 mol) of NaOH was added to the mixture at a concentration of 40% by weight. It was added dropwise over 3.5 hours as an aqueous solution. Water and unreacted β-methylepichlorohydrin were removed from the reaction product by distillation, 550g of toluene was added to dissolve the crude product, salt was separated, and 530g of bisphenol A/β-methylepichlorohydrin type epoxy compound was obtained. I got it. Its epoxy equivalent weight was approximately 200. Hereinafter, this will be referred to as "EP-1". Epoxy compound production example 2 Using 336 g (1.5 mol) of bisphenol F and 1388 g (15 mol) of β-methylepichlorohydrin, 490 g of a bisphenol F/β-methylepichlorohydrin type epoxy compound was otherwise prepared according to the method of Production Example 1 above. Obtained. Its epoxy equivalent weight was approximately 180. Hereinafter, this will be referred to as "EP-2". Epoxy compound production example 3 Hydrogenated bisphenol A 354g (1.5mol) and β-methylepichlorohydrin 1388g (15mol)
540 g of a hydrogenated bisphenol A/β-methylepichlorohydrin type epoxy compound was obtained in the same manner as in Production Example 1 above. Its epoxy equivalent weight was approximately 210. Hereinafter, this will be referred to as "EP-3". Epoxy (meth)acrylate production example 1 400 g (4 mol) of methacrylic acid was added to 800 g (2 mol) of the above epoxy compound EP-1,
20 g of toluethylamine (catalyst) was added to the mixture while heating and stirring at 45°C, and the mixture was maintained at 50°C for 10 hours to react. Next, 20 g of methacrylic acid was further added to this, and the mixture was heated and stirred at 55° C. for 9 hours to obtain epoxy methacrylate. Hereinafter, this will be referred to as "EPA-1". Epoxy (meth)acrylate production example 2 800 g (2 moles) of epoxy compound EP-1,
Add 140g (1 mol) of adipic acid to 150
After heating and stirring at ℃ for 15 hours, cool to 45℃, add 200g (2 moles) of methacrylic acid, add 10g of toluethylamine while stirring, and heat to 50℃ for 10 hours.
I gave it time to react. Next, 10 g of methacrylic acid was added thereto, and the mixture was heated and stirred at 55° C. for 9 hours to obtain epoxy methacrylate. Hereinafter, this will be referred to as "EPA-2". Epoxy (meth)acrylate production examples 3 to 7 Epoxy (meth)acrylate production examples 2 using various epoxy compounds, adipic acid or sebacic acid, and methacrylic acid or acrylic acid as shown in Table 1 below. Various epoxy (meth)acrylates were produced according to the method of . Each of those epoxy (meth)acrylates is referred to as "EPA-3", "EPA-4", "EPA-5",
They are called "EPA-6" and "EPA-7."

[Table] Examples 1 to 8 Comparative Examples 1 to 4 As shown in Table 2, each of the above epoxy (meth)
Using each of the epoxy (meth)acrylates EPA1 to EPA7 produced in the acrylate production example, 20 parts by weight of each of these (meth)acrylates was added with methyl methacrylate ( Example 1 was prepared by blending 60 parts by weight of MMA), 40 parts by weight of 2-hydroxyethyl methacrylate (HEMA), and 15 to 30 parts by weight of various synthetic polymers.
- 8 and various acrylic adhesive compositions of Comparative Examples 1 and 2 were prepared. The method for preparing these adhesive compositions is to heat a mixture of component (B), ie, MMA and HEMA to 50 to 60°C and add synthetic polymer (C) to it while stirring.
was added, dissolved and dispersed within a short period of time, returned to room temperature, and then the epoxy (meth)acrylate produced in each production example was added and mixed with stirring. Separately, as shown in Table 2, Comparative Example 3 was carried out in the same manner using commercially available epoxy methacrylate (Kyoeisha Yushi Kagaku Kogyo Co., Ltd. trade name: Light Ester 3002M), which is said to have excellent flexibility.
An acrylic adhesive composition was prepared. moreover,
As shown in Table 2, an acrylic adhesive composition of Comparative Example 4 was prepared by dissolving nitrile rubber in a mixture of MMA and HEMA. When each of these acrylic adhesive compositions was stored (left) at a temperature of 20°C for 30 days, as shown in Table 2, the composition of Comparative Example 3 caused separation of components, but the composition of each Example The composition did not undergo any separation of components.

【table】

[Table] Next, using the adhesive compositions obtained in each example and comparative example, various two-component or primer type acrylic adhesives were prepared as shown in Table 3 by the following method. . Two-component adhesive preparation method Divide an appropriate amount of the adhesive composition into two equal parts, add 10% by weight of hydroperoxide and 0.1% by weight of hydroquinone to one part to make part A, and add 4 parts of ethylene thiourea to the other part. % by weight, and 4% by weight of trimethylolpropane trimethacrylate to obtain liquid B. Primer type adhesive preparation method An adhesive composition containing 4% by weight of ethylene thiourea and 4% by weight of trimethylolpropane trimethacrylate is used as the main ingredient, and a 2% by weight solution of cumene hydroperoxide in trichloroethane is separately prepared to prepare the primer. And so. Using each of the adhesives obtained, mild steel plates were bonded together according to a conventional method, and heated at 20℃ for 24 hours or 150℃.
The tensile shear strength, T-peel adhesion strength, and impact adhesion strength were measured by the following methods after being left for 10 days at ℃, and the results shown in Table 2 were obtained. Tensile shear adhesive strength JIS K6850 T-peel adhesive strength JIS K6854 Impact adhesive strength JIS K6855

[Table] As is clear from the results in Table 3, the adhesive prepared from the acrylic adhesive composition of each example was 20% lower than the adhesive prepared from the composition of each comparative example.
The T-peel adhesion strength and impact adhesion strength after being left at 150°C for 24 hours and after heat aging at 150°C for 10 days were significantly higher than those of the adhesives prepared from the adhesive compositions of each comparative example. It showed a high value.

Claims (1)

[Claims] 1 (A) A β-methylepihalohydrin-derived bifunctional epoxy compound is reacted with a dibasic acid to elongate the chain, and further reacted with (meth)acrylic acid to form a polymerizable double bond at the terminal. (B) (meth)acrylate monomers other than the monomers described in (A) above, and (C) each component of synthetic high molecular weight polymers. An acrylic adhesive composition that is cured by radical polymerization and has as an essential component. 2 Bifunctional epoxy (meth)acrylate (A)
are bisphenol A/β-methylepihalohydrin type bifunctional epoxy compounds, hydrogenated bisphenol A/β-methylepihalohydrin type bifunctional epoxy compounds, bisphenol F/β-methylepihalohydrin type bifunctional epoxy compounds, and Claim No. 1, which is a bifunctional epoxy (meth)acrylate derived from a β-methylepihalohydrin-derived difunctional epoxy compound selected from hydrogenated bisphenol F/β-methylepihalohydrin-type difunctional epoxy compounds. Composition according to item 1.