JPH0216346B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for adhering a novel thermosetting adhesive, and more specifically, it relates to a method for adhering a novel thermosetting adhesive, and more particularly, it relates to a method for adhering adhesives at high temperatures by partially crosslinking a block copolymer consisting of a monovinyl-substituted aromatic compound polymer block and a conjugated diolefin polymer block. The present invention relates to an adhesion method for obtaining an adhesive with excellent adhesive strength. Conventionally, various solution types made of block copolymers made of a monovinyl-substituted aromatic compound polymer block and a conjugated diolefin polymer block,
Hot-melt type and overpressure type adhesives are widely known (Japanese Patent Publication No. 17037/1983, No. 45-41518).
No. 46-40872, No. 79-330, etc.). Adhesives made from such block copolymers have come to form a category among various adhesives, but the adhesive strength of adhesives made from such block copolymers is excellent at around room temperature. However, their commercial applications are limited due to their inferiority at high temperatures. As a result of extensive research into an adhesive method for producing an adhesive with excellent adhesive strength at high temperatures that overcomes the drawbacks of the block copolymers described above, the inventors have discovered that monovinyl-substituted aromatic compound polymer blocks and conjugated diolefin polymers have been developed. The inventors have discovered that the object can be achieved by partially crosslinking and adhering a block copolymer consisting of blocks, and based on this knowledge, the present invention has been accomplished. That is, the present invention has the general formula A-B-A, (A-B) _o , B(-A-B) _o ,
(A _- B) _-o A, or (A-B) n X is a polyfunctional residue having m bonds, m is an integer of 3 to 7, and n is an integer of 2 to 10], and the monovinyl-substituted aromatic compound content is 10 to 70% by weight. , number average molecular weight is 5000
~500,000 and a crosslinking agent containing an organic peroxide, sulfur, sulfur compounds, or a sulfur-containing compound, and after applying this between the adherends, heat and pressure bonding is performed. The swelling degree of the polymer forming the layer (toluene, 25℃ x 22hrs immersion) is 5 to 100.
This adhesion method is characterized by partially crosslinking the adhesive until it reaches cc/g. In the present invention, the monovinyl-substituted aromatic compound-conjugated diolefin block copolymer (hereinafter referred to as "block copolymer") forming the adhesive layer has the general formula A-B-A, (A-B) _o , B(-A-B) _o ,
(A-B) _-o A, (A-B)mX (A, B,
X, m and n have the same meanings as above), and can be obtained by a living anionic polymerization method using an alkali metal-based initiator. Such block copolymers can be produced by sequentially polymerizing monomers block by block in the presence of the initiator, or by simultaneously charging two types of monomers with different copolymerization reactivity ratios. The trowel can be obtained by a method of obtaining a living block copolymer or by a method of coupling a living block copolymer prepared using the above-mentioned initiator. The block copolymer represented by (A-B) _n
-B can be obtained by coupling a living block copolymer with a polyfunctional coupling agent. In this case, for example, a tetrafunctional coupling agent such as tin tetrachloride or silicon tetrachloride can be used. Monovinyl-substituted aromatic compounds include styrene, α-methylstyrene, O- or P-vinyltoluene, ethylstyrene, vinylxylene, isopropylstyrene, ethylvinylstyrene, tertiary-butylstyrene, diethylstyrene, vinylnaphthalene, etc. Also, a mixture of two or more of these can be selected. Examples of the conjugated diolefin include 1,3-butadiene, 1,3-pentadiene, isoprene, and 2,3-dimethylbutadiene, and mixtures of two or more of these can be selected. Preferred combinations are styrene and 1,3-butadiene and styrene and isoprene. The number average molecular weight of the block copolymer is
It can be selected in the range of 5,000 to 500,000, preferably 20,000 to 400,000. If it is less than 5,000 yen, the resulting adhesive will have poor adhesive strength, and if it exceeds 500,000 yen, the fluidity of the adhesive will be poor and sufficient adhesive strength will not be obtained. The monovinyl-substituted aromatic compound content in the block copolymer is 10 to 70% by weight based on the total polymer.
It can be selected preferably within the range of 10 to 55% by weight; outside this range, a bonded product with excellent adhesive strength cannot be obtained. The block copolymer, which is an important requirement of the present invention, has a swelling degree (toluene, 25℃ x 22hrs immersion) of 5 to 100.
The crosslinking agent that partially crosslinks to form a cc/g polymer is an organic peroxide, such as hydroperoxides, dialkyl peroxides, ketone peroxides, peroxy esters, diacyl peroxides, etc., and cured with these. The combination of accelerators, sulfur, sulfur-containing compounds, sulfur compounds, and vulcanization accelerators can be selected arbitrarily, and there are no restrictions as long as the amount added, crosslinking temperature and time, and these requirements are met. do not have. The degree of swelling referred to here is a value determined by the following formula. Swelling degree = sample weight after soaking - sample weight before soaking / sample weight before soaking × 1 / toluene density It must be partially crosslinked so that the swelling degree is 5 to 100 c.c./g polymer, and the swelling degree is 5 c.c./g. If it is less than c./g polymer, the adhesive strength of the resulting adhesive will be significantly lower than that of an uncrosslinked adhesive, which is not preferred.
Moreover, if it exceeds 100 c.c./g of polymer, the adhesive strength at high temperatures will be poor like uncrosslinked adhesives, which is not preferable. Mixing of the block copolymer and the crosslinking agent does not require any special equipment or method, and may be carried out at a temperature and for a time that does not substantially decompose the crosslinking agent to be mixed. For example, roll mixing, kneader mixing, extrusion mixing, solution mixing, etc. can be used. In the method of the present invention, the adhesion method itself, which is carried out using a mixture of a block copolymer and a crosslinking agent, does not require any special equipment or method, and can be carried out by a simple conventional method. That is, a solution prepared by dissolving a block copolymer and a crosslinking agent in a suitable solvent is applied to an adherend, the other adherend is placed on top of the adherend, and the solvent is removed and partial crosslinking is performed by heating. In addition, after applying to one adherend,
After removing the solvent, another adherend is placed on top of the other adherend, and partial crosslinking is performed by applying heat and pressure. Alternatively, a method using a solution of a block copolymer and a crosslinking agent can be used, such as sandwiching a film obtained by casting a solution between adherends and performing partial cross-bonding by heating and pressurizing. In addition, a roll mixture or a kneader mixture of a block copolymer and a crosslinking agent can be formed into a thin film using a press or calendar roll, and the film can be sandwiched between adherends to perform partial crosslinking by heating and pressurizing. Any method may be used. Antioxidants, stabilizers, ultraviolet absorbers, etc. can be added to the block copolymer used in the present invention, and various thermoplastic resins, unvulcanized rubber,
It is also possible to incorporate tackifiers, plasticizers, fillers and other additives. On the other hand, in the present invention, any adherend that forms an adhesive together with the partially crosslinked block copolymer can be used as long as it contains a material that can adhere to the block copolymer. Examples of materials that can be bonded to such block copolymers include metals such as aluminum, tin, brass, lead, and iron, paper, cellophane, wood, fabrics such as polyester cloth, polyamide cloth, cotton cloth, and aramid cloth; Plastic materials include polyolefin polymers such as polyethylene and polypropylene, polystyrene polymers such as polystyrene, impact-resistant polystyrene, AS resin, ABS resin, and MBS resin, nylon-6, nylon-66, nylon-6, 10, Polyamide resins such as nylon-11, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, vinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride, methacrylic resins such as polymethyl methacrylate, polycarbonate resins, and polyphenylene. Examples include nitrile resins such as ether resins, ethylene-vinyl acetate resins, polyvinyl alcohol resins, and acrylonitrile-methyl acrylate resins. Other examples include thermosetting resins such as epoxy resins, phenolic resins, and unsaturated polyester resins, and vulcanized rubber. Examples are shown below. The examples are representative of the invention but are not intended to limit the scope of the invention. Example 1, Comparative Example 1 2,5-dimethylhexane was added to 100 g of a styrene-butadiene block copolymer having blocks of butadiene-styrene-butadiene-styrene, a styrene content of 38% by weight, and a number average molecular weight of 60,000. -2,5-dihydroperoxide
0.005 mol was mixed at 100°C for 10 minutes using a mixing roll. Next, this mixture was preheated for 7 minutes at 120° C. using a hot press, and then pressed for 3 minutes (50 kgf/cm ² ) to produce an uncrosslinked sheet with a thickness of 0.4 mm. This sheet was sandwiched between 1.6 mm thick unpolished, toluene-degreased aluminum plates (using a 0.2 mm aluminum plate spacer), preheated at 200°C for 30 seconds, and then pressurized for 2 minutes (25 Kgf/cm ² ) for a shear adhesion test. Got a piece. Using this test piece, a shear test (shear rate 10 mm/min) was conducted at a measurement temperature of 27°C to 160°C.
The results are shown in Table 1. 0.2 cross-linked under the same conditions as adhesion
Table 1 also shows the results of the toluene immersion test (25°C x 22 hours) for the mm sheet. Further, as a comparative example, the results of a sample without the addition of a crosslinking agent are also shown in Table 1. As can be seen from Table 1, adhesives having a partially crosslinked block copolymer with a swelling degree of about 17 c.c./g polymer as an adhesive layer have a higher adhesive layer than those with an uncrosslinked block copolymer as an adhesive layer. It has excellent adhesive strength in high temperature areas, especially at temperatures above 120°C.

[Table] Examples 2 to 6, Comparative Examples 2 to 12 For 100 g of the block copolymer of Example 1, dicumyl peroxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydro peroxide
0.005 mol was mixed in the same manner as in Example 1, and then a sheet was produced. This sheet is 0.2mm thick, unpolished,
Scissors between toluene-degreased aluminum plates (0.2mm aluminum plate spacer used) After preheating at 160℃ and 200℃ for 30 seconds, heat and press for 2 minutes and 5 minutes (pressure 25Kgf/cm ² )
An adhesive was obtained. This adhesive was cut to a width of 25 mm to provide a test piece for a peel test. The peeling test was carried out at a peeling rate of 200 mm/min under temperature conditions of 20°C and 120°C. The results are shown in Table 2. Table 2 also shows the results of a toluene immersion test (25°C x 22 hours) of a 0.2 mm sheet crosslinked under the same conditions as for adhesion.

【table】

[Table] As can be seen from Table 2, adhesives in which a partially crosslinked block copolymer having a specific swelling degree is present as an adhesive layer have excellent peel strength at 27°C and 120°C. It was possible to put it into practical use. Example 7 (Styrene-butadiene) Has a _4- silicon block, has a styrene content of 30% by weight, and has a number average molecular weight of
To 100 parts by weight of a mixture consisting of 100,000 styrene-butadiene radial teleblock copolymer and 0.001 mol of dicumyl peroxide, 30 parts by weight of coumaron-indene resin (Kumaron AH, manufactured by Ouchi Shinko) and α-pinene polymer (YS An adhesive sheet was prepared in the same manner as in Example 1, containing 20% of Resin A800 (manufactured by Cheap Oil Co., Ltd.) by weight. Using this adhesive sheet, it was bonded to the aluminum plate used in Example 2 under crosslinking conditions of 200° C. for 5 minutes. The degree of swelling of the cross-linked product of the block copolymer containing 0.001 mole of dicumyl peroxide at 200°C for 5 minutes was 22 c.c./g polymer, and the swelling degree of the above adhesive at 27°C using this as the base adhesive was 22 c.c./g polymer. The peel strength was 11.2 kgf/52 mm, and the peel strength at 120°C was 4.2 kgf/25 mm, which were sufficient for practical use. Comparative Example 13 Styrene-butadiene radial teleblock copolymer of Example 7 and dicumyl peroxide
Example 7 to 100 parts by weight of a mixture consisting of 0.005 mol
An adhesive sheet was obtained to which the compounding agent used in was added. Using this sheet, an adhesive was obtained in the same manner as in Example 7. The degree of swelling of the crosslinked product of the block copolymer containing 0.005 mole of dicumyl peroxide at 200°C for 5 minutes was 1 c.c./g polymer, and the swelling degree of the above adhesive product using this as the base adhesive at 27°C The peel strength at 120℃ is 1.4Kgf/25mm.
It was inferior at 0.5Kgf/25mm and could not be put to practical use.

Claims (1)

[Claims] 1 General formula A-B-A, (A-B) _o , B (-A-B)
_o , (A-B) _-o A, or ₍ A-B) n block, X is a polyfunctional residue having m bonds, m is an integer of 3 to 7, n is an integer of 2 to 10], and the monovinyl-substituted aromatic compound content is 10 to 70. Weight%, number average molecular weight is 5000
~500,000 and a crosslinking agent containing an organic peroxide, sulfur, sulfur compounds, or a sulfur-containing compound, and after applying this between the adherends, heat and pressure bonding is performed. The swelling degree of the polymer forming the layer (toluene, 25℃ x 22hrs immersion) is 5 to 100.
An adhesion method characterized by partially crosslinking until cc/g.