JPS6331385B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a novel laminate. More particularly, the present invention relates to laminates with improved interlayer adhesion. (Prior art and problems) Conventionally, different types of materials have been bonded together to form a laminate, which gives the advantages of both materials, or the same material is sandwiched between different types of materials to form a laminate. Many attempts have been made to produce various laminates that compensate for the deficiencies of the outer layer material. Materials for such laminates include metal foils such as aluminum foil and copper foil, paper, cellophane, and various thermoplastic resins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, saponified Ethylene-vinyl acetate copolymer, polyvinyl chloride, polyethylene terephthalate, nylon, polycarbonate, polystyrene, high-impact polystyrene, polyvinylidene chloride, ABS resin, etc. are used. These laminates are used in the form of sheets, films, blow molded products, and the like. These laminates are generally produced by bonding sheets or films of the same or different materials using an adhesive, or by coextrusion without using an adhesive. However, depending on the type of materials to be laminated or their combination, a sufficient adhesive effect may not be obtained. Especially when obtaining a laminate by a coextrusion method that does not use an adhesive, mutual adhesiveness may not be obtained. It is not possible to use materials that do not exist. Therefore, when obtaining a laminate of mutually non-adhesive materials using a coextrusion method, a method is used in which a material that is adhesive to both materials is used as an adhesive layer, such as ethylene-vinyl acetate copolymer. , ionomer resin,
Styrene-butadiene block copolymers and the like are used. However, these resins also have problems, such as not necessarily providing a sufficient adhesive effect depending on the type of material to be coextruded, and poor durability of adhesive strength, poor water resistance, etc. (Means for solving the problem) As a result of studying the problem, the present inventors found that
A modified block copolymer obtained by grafting an unsaturated carboxylic acid or its derivative onto a vinyl aromatic compound-conjugated diene compound block copolymer has extremely good adhesion to various materials and is suitable for laminate applications. This discovery led to the present invention. The present invention relates to a laminate containing a two-layer structure of AB, a three-layer structure of A-B-A or ABC-C (A and C are different), in which the B layer is made of a vinyl aromatic compound. The weight ratio with the conjugated diene compound exceeds 70/30,
This layer is mainly composed of a modified block copolymer obtained by grafting an unsaturated carboxylic acid or its derivative onto a vinyl aromatic compound-conjugated diene compound block copolymer having a ratio of 90/10 or less, and the A layer and C layer are: This laminate is characterized by being a layer that can be bonded to layer B. The present invention will be explained in detail below. In the present invention, regarding a modified block copolymer (hereinafter referred to as "modified block copolymer") in which an unsaturated carboxylic acid or a derivative thereof is grafted onto a vinyl aromatic compound-conjugated diene compound block copolymer forming layer B. state A vinyl aromatic compound that serves as a base for such a modified block copolymer.
Conjugated diene compound block copolymers (hereinafter referred to as ``block copolymers'') contain at least one polymer block mainly composed of vinyl aromatic compounds.
contains at least one polymer block mainly composed of a conjugated diene compound, preferably two or more, and the weight ratio of the vinyl aromatic compound to the conjugated diene compound is more than 70/30 and less than 90/10. Limited to a range. In addition, in the polymer block mainly composed of a vinyl aromatic compound of the block copolymer, the weight ratio of the vinyl aromatic compound to the conjugated diene compound is limited to a composition range of 100/0 to 60/40, The distribution of the conjugated diene compound, which is a minor component, in the molecular chain may be random, tapered (in which the monomer component increases or decreases along the molecular chain), partially block-like, or a combination thereof. On the other hand, in a polymer block mainly composed of a conjugated diene compound, the weight ratio of the vinyl aromatic compound and the conjugated diene compound is 0/100.
The distribution of the vinyl aromatic compound, which is a minor component, in the molecular chain may be random, tapered, partially block-like, or a combination thereof. The vinyl aromatic compound constituting the block copolymer of the present invention may be one or two of styrene, α-methylstyrene, vinyltoluene, etc.
Among them, styrene is the most preferred. The conjugated diene compound is selected from one or more of butadiene, isoprene, 1,3-pentadiene, etc., and butadiene or isoprene is most preferred. Furthermore, the block copolymer has a number average molecular weight of
The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is preferably within the range of 1.05 to 10. Furthermore, the molecular structure of the block copolymer may be linear, branched, radial, or a combination thereof. In addition, when butadiene is used as the conjugated diene compound, the microstructure of the butadiene portion of the block copolymer is 1,
Preferably, the 4-cis content is 20 to 50% and the 1,2-vinyl content is 5 to 40%. The various limitations regarding the block copolymer described above are extremely important in order for the block copolymer to have sufficient adhesion ability to other materials when modified. The block copolymer used in the present invention is usually produced by polymerizing a vinyl aromatic compound and a conjugated diene compound in an inert hydrocarbon solvent such as hexane, cyclohexane, benzene, or toluene using an organolithium compound such as butyllithium as a polymerization catalyst. Obtained by anionic block copolymerization. It is also possible to make branched or radial block copolymers by reacting the block copolymers with lithium active terminals obtained by the above method with a polyfunctional coupling agent such as carbon tetrachloride, silicon tetrachloride, etc. It is. In addition, any block copolymer obtained by any production method can be used as the substrate for the modified block copolymer of the present invention as long as it falls within the above-mentioned limits. Examples of unsaturated carboxylic acids or derivatives thereof that can be grafted onto the block copolymer of the present invention to form a modified block copolymer include maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic acid, and crotonic acid. acid, cis-4-cyclohexene-1,2-dicarboxylic acid, endo-cis-bicyclo[2,2,1]-5-heptene-2,3-dicarboxylic acid, and derivatives of these include:
Examples include acid anhydrides, esters, acid amides, dicarboxylic imides, etc. of these carboxylic acids, and among these, dicarboxylic acid anhydrides are preferred, and maleic anhydride is particularly preferred. The content of unsaturated carboxylic acid or its derivative in the modified block copolymer of the present invention is from 0.01 to
30% by weight, preferably 0.05-10% by weight. If it is less than 0.01% by weight, there is almost no effect on the adhesive properties of the graft, and if it exceeds 30% by weight, the effect will not become large. The modified block copolymer of the present invention can be produced by grafting an unsaturated carboxylic acid or a derivative thereof to the block copolymer in the melt or solution state with or without the use of a radical initiator. It will be done. The method for producing these modified block copolymers is not particularly limited in the present invention, but the modified block copolymers obtained may contain undesirable components such as gels, or have a significantly reduced melt viscosity, resulting in poor processability. A manufacturing method that causes deterioration is not preferred. A preferred method is, for example, a method in which the block copolymer and the unsaturated carboxylic acid or its derivative are reacted in an extruder under melt-mixing conditions that substantially do not generate radicals. On the other hand, in the present invention, the other layers that form the laminate together with the modified block copolymer, that is, the A layer and the C layer, can be any material as long as it contains a material that can adhere to the modified block copolymer. be. Examples of materials that can be bonded to such modified block copolymers include metal foils such as aluminum, tin, brass, and copper, paper, cellophane, and thermoplastic materials such as polyolefin polymers such as polyethylene and polypropylene. , polystyrene, high impact polystyrene, AS resin, ABS resin, MBS
Polystyrene polymers such as resins, nylon-6,
Polyamide resins such as nylon-6, 6, nylon-6, 10, nylon-11, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, vinyl chloride resins such as polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate Examples include methacrylic resins, polycarbonate resins, polyphenylene ether resins, ethylene-vinyl acetate resins, and polyvinyl alcohol resins. In the present invention, the modified block copolymer forming layer B can be used not only alone but also in combination of two or more. In addition, in layer B, the modified block copolymer is preferably 60% by weight in order to maintain adhesion.
Must contain 75% by weight. The modified block copolymer of layer B contains antioxidants, stabilizers,
UV inhibitors and the like can be added, and various thermoplastic resins, unvulcanized rubber, plasticizers and other additives can also be blended within a range that does not deteriorate the adhesiveness of the modified block copolymer. Further, the A layer and the C layer may contain other components. As a method for manufacturing these laminates, any commonly used method can be used. Examples of this method include, for example, sandwiching and pressing the modified block copolymer between films or sheets of materials to be laminated, using the modified block copolymer as a hot melt or solution type adhesive, and laminating. A method in which the materials to be layered are extruded through a mold using an extruder or the like and welded in a softened state, a method in which the materials to be laminated are coextruded from a single die, and a modified block copolymer is extruded and coated on one of the materials. There are other methods, such as a method of laminating another layer on this extrusion coated laminate. Note that the materials forming these laminates may be surface-treated to enhance adhesion. The amount of the modified block copolymer to be used in the laminate may be such that the laminate has sufficient adhesion performance, but the modified block copolymer may impart impact resistance and flexibility to the laminate. If a special function is to be provided, such as, a sufficient amount is required to fully demonstrate that function. The laminate obtained by the method of the present invention includes a film,
It can be widely used in the form of a packaging film in the form of a sheet, and as a molding material for vacuum forming and pressure forming of multilayer hollow products by coextrusion. (Examples, Effects) Hereinafter, some examples will be shown, but they do not limit the present invention. Example 1 and Reference Examples It has a butadiene-styrene-butadiene-styrene block, with a styrene content of 38% by weight,
A modified block copolymer in which maleic anhydride was grafted onto a styrene-butadiene copolymer having a number average molecular weight of 60,000 was obtained by the method shown below. 1.5 parts by weight of maleic anhydride and 0.2 parts by weight of phenothiazine were added to 100 parts by weight of the above styrene-butadiene copolymer, and these were mixed uniformly using a mixer. This mixture was supplied to a screw type extruder (single screw, screw diameter 40 mm, L/D=24, full flight type screw) under a nitrogen atmosphere, and a maleation reaction was carried out at a cylinder temperature of 200°C. Unreacted maleic anhydride was removed from the obtained polymer under reduced pressure. The analysis results showed that the melt index (G conditions) was 7.2, the toluene insoluble content was 0.05% by weight, and the amount of maleic anhydride added was 0.70% by weight (reference example). Furthermore, a block copolymer having styrene-butadiene-styrene blocks, a styrene content of 80% by weight, and a number average molecular weight of 90,000 was grafted with maleic anhydride in an extruder using the same method to form a modified block copolymer. A combined product (referred to as sample A) was obtained. The melt index (G conditions) of sample A is 3.1, the toluene insoluble content is 0.08%, and the amount of maleic anhydride added is
It was 0.87%. A sheet of sample A with a thickness of 0.3 mm was made and heat-compressed with various materials shown in Table 1, and the peel strength was measured. The results are shown in Table 1. As shown in Table 1, the laminate of the present invention has excellent adhesion.

[Table] Example 2, Comparative Example 1 Using a 45 m/m extruder, a 40 m/m extruder, and a 45 m/m extruder, three layers of saponified EVA/Sample A/High Infected Polystyrene were coextruded. For comparison, similar coextrusion was carried out using the polymer before modification of Sample A. Table 2 shows the resulting peel strength between each layer. Note that each resin was extruded under the conditions shown in Table 3.

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Claims (1)

[Claims] 1 A-B two-layer structure, A-B-A or A-B
- Vinyl aromatic laminate having a three-layer structure of C (A and C are different), in which layer B has a weight ratio of vinyl aromatic compound to conjugated diene compound of more than 70/30 and less than 90/10 This layer is mainly composed of a modified block copolymer obtained by grafting an unsaturated carboxylic acid or its derivative onto a conjugated diene compound block copolymer, and the A layer and C layer are layers that can be bonded to the B layer. A new laminate characterized by: 2. The B layer contains at least the modified block copolymer.
The laminate according to claim 1, which is a layer containing 60% by weight.