JPS623872B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a novel adhesive; more specifically, it contains as a component a block copolymer consisting of a conjugated diolefin polymer block and a monovinyl-substituted aromatic compound polymer block, and is particularly suitable for bonding polyolefin resin materials and metal materials. Concerning suitable adhesives. In general, polyolefin resins such as polyethylene and polypropylene are well known as the most difficult plastics to adhere to. Since polyolefin resins are insoluble or poorly soluble in general solvents, they cannot be bonded by wetting them with a solvent or by preparing their own solvent solution. In addition, since it is highly crystalline and has no polar groups at all, even if ordinary commercially available adhesives are used, it will not adhere at all, or even if it does, it will only show weak adhesive strength. When bonding polyolefin resins that are difficult to bond, conventional methods include surface treatment of the adherend, such as roughening the surface by sandblasting, or immersion in a solvent such as perchlorethylene or trichlorethylene at approximately 80°C. The surface can be roughened by dipping it for a period of time to elute the amorphous and low molecular weight parts of the surface, or by using gas flame, heated air, sulfuric acid-chromic acid mixture, electric discharge, ultraviolet rays or radiation irradiation. Measures such as oxidizing and making it polar have been taken. However, even with these methods, sufficient adhesive strength cannot be obtained, and the polyolefin resin has not yet been completely bonded. Further, the above method requires extremely complicated operations and has the disadvantage of altering or deteriorating the surface of the adherend. The inventors of the present invention have conducted intensive studies on a simple and effective adhesive for polyolefin resins that overcomes all of the above-mentioned drawbacks, especially adhesives that firmly bond polyolefin resins and metals. The inventors discovered that the object could be achieved by creating an adhesive with a specific composition containing a block copolymer consisting of a combined block and a monovinyl-substituted aromatic compound polymer block, and based on this knowledge, the present invention was accomplished. . That is, the present invention provides (a) the general formula A-B-A, (A-B) _o , B-(A-B) _o , (A-B)- _o A, or (A-B) _n X ( In the formula, B is a block substantially composed of a conjugated diolefin polymer, A is a block substantially composed of a monovinyl-substituted aromatic compound polymer, X is a polyfunctional residue having m bonds, and m is 3 an integer of ~7,
n is an integer from 2 to 10), and the monovinyl-substituted aromatic compound content is
10 to 70% by weight, 100 parts by weight of at least one block copolymer with a molecular weight in the range of 5,000 to 500,000, (b) 10 to 100 parts by weight of ethylene-vinyl acetate copolymer, (c) ethylene-alkyl acrylate The present invention provides an adhesive comprising 20 to 200 parts by weight of a copolymer, (d) 5 to 100 parts by weight of a phenolic resin, and (e) 30 to 200 parts by weight of an adhesive resin. The block copolymer used as component (a) of the present invention has the general formula A-B-A, (A-B) _o , B-(A
-B) _o , (A-B) - _o A, (A-B) _n X (A, B, X, n and m in the formula have the same meanings as above)
It 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. It 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 X can be obtained by coupling the living block copolymer A-B with a polyfunctional coupling agent. In this case, it is possible to use, for example, tetrafunctional coupling agents such as tin tetrachloride and silicon tetrachloride. Conjugated diolefins include 1,3-butadiene, 1,3-pentadiene, isoprene, 2,3
-dimethylbutadiene, and mixtures of two or more of these can be selected. Monovinyl-substituted aromatic compounds include styrene, α-methylstyrene, o- or p-vinyltoluene, ethylstyrene, vinylxylene, isopropylstyrene, ethylvinyltoluene, tertiary-butylstyrene, diethylstyrene, vinylnaphthalene, etc. Also, a mixture of two or more of these can be selected. Preferred combinations are 1,3-butadiene and styrene and isoprene and styrene. The molecular weight of the block copolymer is 5000~
500,000, preferably in the range of 20,000 to 400,000. If it is less than 5000, the cohesive force of the resulting adhesive will be poor and sufficient adhesive strength will not be obtained;
If it exceeds 100%, the viscosity of the adhesive will be high and it will be impractical. 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 in the range of 10 to 55% by weight; outside this range, the resulting adhesive will have poor adhesive strength, which is not preferred. The ethylene-vinyl acetate copolymer used as component (b) of the present invention has a vinyl acetate content of 10 to 45
% by weight, preferably in the range 20-40% by weight,
Melt index (JIS K 6760) 2~400
(g/10 minutes), preferably in the range of 20 to 350 (g/10 minutes). Vinyl acetate content
If it is less than 10% by weight, the resulting adhesive will have poor adhesion to metals, and if it exceeds 45% by weight, it will have poor adhesion to polyolefin resins, which is undesirable. If the melt index is less than 2 (g/10 minutes), the resulting adhesive will have poor adhesive strength, and if it exceeds 400 (g/10 minutes), the high temperature properties will deteriorate, which is undesirable. The ethylene-vinyl acetate copolymer is used in an amount of 10 to 100 parts by weight per 100 parts by weight of the block copolymer.
Used in the range of 100 parts by weight. Outside this range, the desired adhesive strength cannot be obtained, which is not preferable. The ethylene-alkyl acrylate copolymer used as component (iii) of the present invention has an alkyl acrylate content in the range of 10 to 50% by weight, and a melt index (JIS K 6760) of 0.5 to 50 (g/
(10 minutes) can be selected. Alkyl acrylate is an alkyl ester of (meth)acrylic acid in which the alkyl group has 1 to 12 carbon atoms. A preferred alkyl acrylate is ethyl acrylate. When the alkyl acrylate content is outside the above range, desired adhesive strength cannot be obtained. When the melt index is less than 0.5 (g/10 minutes), the adhesive strength of the resulting adhesive is poor and
If the temperature exceeds 100 min), the high-temperature properties will deteriorate, which is undesirable.
The ethylene-alkyl acrylate copolymer is used in an amount of 20 to 200 parts by weight based on 100 parts by weight of the block copolymer. Outside this range, the desired adhesive strength cannot be obtained, which is not preferable. The phenolic resin used as component (2) of the present invention is a reaction product of phenol or alkylphenol and formaldehyde, and is not limited as long as it is thermoplastic and non-thermally reactive. It may also be one modified with a natural resin (for example, rosin, etc.). Specific examples of phenolic resins include phenol, p-tertiary octylphenol, p-tertiary amylphenol,
Examples include condensates of p-tertiary butylphenol and formaldehyde. The phenolic resin is used in an amount of 5 to 100 parts by weight of the block copolymer.
Used in the range of 100 parts by weight. If it is less than 5 parts by weight, the resulting adhesive will have poor adhesive strength, and if it exceeds 100 parts by weight, the resulting adhesive will be brittle and undesirable. The adhesive resin used as the component (e) of the present invention is particularly limited to one or more of rosin resins, terpene resins, hydrogenated hydrocarbon resins, styrene-olefin copolymer resins, etc. It's not a thing. Specific examples of rosin-based resins include rosin, hydrogenated rosin, disproportionated rosin, and glycerin esters and pentaerythritol esters thereof. Specific examples of the terpene resin include α-pinene polymer, β-pinene polymer, dipentene polymer, α-pinene-phenol copolymer, and β-pinene-phenol copolymer. Specific examples of hydrogenated hydrocarbon resins include:
Products obtained by polymerizing and hydrogenating the C ₄ and C ₅ fractions in cracked naphtha oil as raw materials, products obtained by polymerizing and hydrogenating the C ₉ fraction in cracked naphtha oil as raw materials, and cyclopentadiene in cracked naphtha oil Examples include those obtained by polymerizing and hydrogenating cracked oil whose main component is The adhesive resin is 30 parts by weight per 100 parts by weight of the block copolymer.
Used in the range of ~200 parts by weight. If it is less than 30 parts by weight, the desired adhesive strength cannot be obtained, and if it exceeds 200 parts by weight, the resulting adhesive itself becomes too sticky.
Unfavorable for work. If desired, auxiliary substances commonly used in adhesives, such as antioxidants, may be added to the adhesive of the present invention. Since each block in a block copolymer undergoes a different deterioration mechanism, it can be made more effective by combining various antioxidants. Further, if necessary, common elastomers, plasticizers, pigments, fillers, etc. can be added. Various methods can be used to manufacture the adhesive of the present invention. For example, a melting kettle, kneader, mixing roll, extruder, internal mixer, etc. can be used. The adhesive of the present invention includes polyolefin resins (e.g., polyethylene, polypropylene, ethylene copolymers, etc.), polyolefin resins, metals (e.g., iron, aluminum, stainless steel, copper, brass, etc.), paper, wood, and polyolefin resins. Effective for adhesion to plastics other than resin-based resins. In particular, it shows extremely excellent adhesion to polyolefin resins and metals. Various methods can be used for adhesion.
For example, extruders, hot melt applicators,
A method using a hot-melt coater or the like, or a method in which the adhesive is formed into a film, pellet, or powder, which is sandwiched between adherends and heated and pressed, etc. can be used. Examples are shown below. The examples illustrate the invention but do not limit the scope of the invention. Examples 1 to 6 In a nitrogen gas atmosphere, n-butyllithium was added to an n-hexane solution containing a mixture of 1,3-butadiene and styrene, and after most of all monomers were copolymerized, 1. An n-hexane solution containing a mixture of 3-butadiene and styrene was added, and polymerization was carried out until almost all of the additional monomer was copolymerized. The obtained polymer is a polybutadiene-polystyrene-polybutadiene-polystyrene type block copolymer, with a molecular weight of 80,000,
The styrene content was 40% by weight. Based on 100 parts by weight of the obtained block copolymer, 65 parts by weight of ethylene-vinyl acetate copolymer (Sumitate KE-10, manufactured by Sumitomo Chemical, vinyl acetate content 28% by weight, melt index 300), ethylene- 150 parts by weight of ethyl acrylate (NUC 9169, manufactured by Nippon Unicar, ethyl acrylate content 20% by weight, melt index 20), 65 parts by weight of phenolic resin (CKM-2400; manufactured by Showa Union Gosei), α-pinene polymer (Picolite) A-115,
(manufactured by Etsuo Chemical) 130 parts by weight and 1,1-bis-(4
1 part by weight of -hydroxyphenyl)-cyclohexane (Antigen W, manufactured by Sumitomo Chemical) was charged into a pressure kneader and melt-kneaded at 120°C to obtain a composition. This composition was made into a 0.4 mm thick sheet using a hot press. Sand processed 1.6 as adherend
mm thick mild steel plate and polyethylene (molded into a 1 mm thick sheet) having a density of 0.947 g/cm ³ and a melt index of 0.15 were used. 160 adhesive sheet and mild steel plate
C. and then preheated to 200.degree. C., polyethylene sheets were overlapped and crimped to create a laminate of mild steel plate/adhesive/polyethylene. The adhesive/polyethylene double layer was cut into 10 mm width samples to be used as peel test samples. Peeling test: Peeling speed 50
Performed at mm/min. The results are shown in Table 1. In the above formulation, the results of varying the amounts of various compounding ingredients are shown as comparative examples, as well as adhesive resins such as terpene-phenol resin (YS Resin Px 600, manufactured by Yasushi Oil Co., Ltd.), rosin glycerin ester (Ester Gum H, manufactured by Arakawa Forestry Chemical Co., Ltd.) Table 1 also shows the results using a hydrogenated hydrocarbon resin (Alcon M90, manufactured by Arakawa Forestry Chemical Co., Ltd.).

【table】

[Table] Example 7 In a nitrogen gas atmosphere, n-butyllithium is added to a toluene solution containing styrene to initiate polymerization of styrene, and after 99% or more of the styrene has been polymerized, a solution containing 1,3-butadiene is added. 99 of 1,3-butadiene added by adding toluene solution.
After % or more had polymerized, silicon tetrachloride was added to carry out a coupling reaction without losing activity. The obtained polymer is a (polystyrene-polybutadiene) ₄ Si type block copolymer,
It had a molecular weight of 170,000 and a styrene content of 30% by weight. Based on 100 parts by weight of the obtained block copolymer, 30 parts by weight of ethylene-vinyl acetate copolymer (Evaflex 150, manufactured by Mitsui Polychemicals, vinyl acetate content 33% by weight, melt index 25),
75 parts by weight of ethylene-alkyl acrylate copolymer (NUC 9169), phenolic resin (CKM
2400) 30 parts by weight, α-pinene polymer (YS resin
A800, cheap crude oil) 65 parts by weight and 1 1-bis-(4-hydroxyphenyl)-cyclohexane
After kneading parts by weight in the same manner as in Example 1, the same test was conducted, and the peel strength was 10 Kgf/cm (cohesive failure at the iron interface and in some parts), which was sufficient for practical use.

Claims (1)

[Claims] 1 (a) General formula A-B-A, (A-B) _o , B-(A-B) _o , (A-B)- _o A, or (A-B) _n X (in the formula, B is a block substantially composed of a conjugated diolefin polymer, A is a block substantially composed of a monovinyl-substituted aromatic compound polymer, X is a polyfunctional residue having m bonds, m is an integer from 3 to 7,
n is an integer from 2 to 10), and the monovinyl-substituted aromatic compound content is
10 to 70% by weight, 100 parts by weight of at least one block copolymer with a molecular weight in the range of 5,000 to 500,000, (b) 10 to 100 parts by weight of ethylene-vinyl acetate copolymer, (c) ethylene-alkyl acrylate An adhesive comprising 20 to 200 parts by weight of a copolymer, (d) 5 to 100 parts by weight of a phenolic resin, and (e) 30 to 200 parts by weight of an adhesive resin. 2 B in the general formula is 1,3-butadiene, 1,3
- The adhesive according to claim 1, which is a block consisting of a polymer of pentadiene, isoprene or 2,3-dimethylbutadiene. 3. The adhesive according to claim 1, wherein A in the general formula is a block consisting of styrene or a polymer of alkyl-substituted styrene.