JPH03228B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminate having a layer of thermoplastic fluorine-containing resin (hereinafter abbreviated as fluororesin) and having strong interlayer adhesive strength. Fluororesins generally have excellent solvent resistance, have no water absorption, and have excellent weather resistance, heat resistance, abrasion resistance, and non-adhesion properties among plastics. Polytetrafluoroethylene (PTEF) is a representative polymer of this fluororesin, and because of its high heat resistance and excellent solvent resistance, it is used as inner corrosion protection and packing for chemical equipment piping, as well as for its dielectric constant and It is used as an insulating material for electric wires and cables due to its low dielectric loss and high resistivity, and as an oil-free bearing and sliding material due to its excellent surface lubricity, but it has a high melting point and is difficult to melt when heated. Therefore, it has poor moldability, and has the drawback that it must be molded using the usual sintering method. Therefore, TPFE can be molded using fluorine-containing unsaturated monomers other than tetrafluoroethylene, copolymers with tetrafluoroethylene using other unsaturated monomers, or fluororesins without tetrafluoroethylene. With improvements in properties, it has become possible to obtain thermoplastic materials with the properties of TPFE. However, although these fluororesins have the above-mentioned properties, they are expensive, and therefore, for general purposes, it is thought that lamination with other inexpensive base materials will be useful. However, since fluororesin is non-adhesive,
Difficult to adhere to other base materials. For this reason, various methods have been studied to improve the adhesiveness between fluororesins and other base materials. For example, methods for modifying the surface of fluororesin so that it can be bonded with an adhesive include wet treatment of the surface of the fluororesin molded product with an alkali metal solution, corona discharge, plasma discharge, sputtering, etc. Dry processing methods such as etching are known. In addition, there are methods such as a method of melting the surface with a special solvent that dissolves the fluororesin and adhering it to another base material, and a method of physically adhering the glass mat and the fluororesin. On the other hand, adhesive resins for bonding fluororesins and other base materials have also been proposed. For example, certain ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, or modified products thereof
86748, JP 57-12645), epoxy group-containing polyolefin (JP 57-8155, JP 57-212055), a resin composition of a copolymer grafted with vinylidene fluoride and a methyl methacrylate polymer. (Japanese Unexamined Patent Publication No. 57-12646), etc. are known. However, these prior art techniques are not sufficient in terms of molding methods or adhesive properties, and there are limits to the types of base materials to which they can be bonded.
In the lamination of thermoplastic fluororesin and ethylene-vinyl acetate copolymer disclosed in No. 56-86748 and No. 57-12645, a large amount of vinyl acetate is copolymerized with ethylene to improve the adhesion. When introduced in the form of , the mechanical strength of the copolymer decreases and the adhesive strength is not improved as much, which is undesirable. The present invention was made with the aim of improving these drawbacks, and was made based on the discovery that the use of a specific modified polymer significantly improves adhesion and achieves the purpose. That is, the present invention contains at least a portion of an ethylene polymer graft-copolymerized with vinyl acetate, and the content of the grafted vinyl acetate is 5% by weight or more and the content of the total vinyl acetate is 20 to 80% by weight. This is a laminate characterized by comprising a layer of a resin-like modified ethylene polymer or a modified ethylene polymer composition containing an ethylene polymer as a main component, and a layer of a thermoplastic fluorine-containing resin. Since the laminate of the present invention has strong interlayer adhesion and has the advantages of fluororesin and the properties of other base materials, it can be highly expected to be applied not only to industrial products but also to the field of daily necessities. The ethylene polymer used in the present invention is an ethylene homopolymer or a majority of ethylene and α-olefin (propylene, butene-1, hexane-1).
1, heptene-1,4-methylpentene-1, octene-1, etc. having 3 to 12 carbon atoms), vinyl esters (vinyl acetate, etc.), unsaturated organic acids or their derivatives (acrylic acid, methyl acrylate, etc.) , ethyl acrylate, methyl methacrylate, maleic acid, itaconic acid, maleic anhydride, etc.), or processed products of these polymers by oxidation, chlorination, saponification, etc. are suitable.
Here, the copolymer may be in random, block, or graft form, but in the case of a copolymer of ethylene and vinyl acetate, a copolymer that is not in graft form is used. Specific examples of ethylene polymers include low, medium, and high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl acetate copolymer.
Examples include acrylic acid copolymers and maleic anhydride grafted polyethylene, but those with a crystallinity of 50% or less are preferred. Among these, ethylene-vinyl acetate copolymers are preferred, particularly ethylene-vinyl acetate copolymers having a vinyl acetate content of 15% by weight or more. This kind of ethylene polymer is the main component (50% by weight)
As long as the above) is satisfied, there is no problem in using an ethylene polymer composition containing other polymers. These ethylene polymers or ethylene polymer compositions can be blended with various additives, inorganic fillers, colorants, etc. that are commonly used in resins. Furthermore, examples of the fluororesin that can be used in the present invention include polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, Tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-
Propylene copolymer, tetrafluoroethylene
Commercially available products such as perfluoroalkyl vinyl ether copolymers can be used as appropriate, and among them, polyvinyl fluoride, polyvinylidene fluoride, and the like are preferred.
Furthermore, other polymers that are compatible with the fluororesin may be blended and used, and a blend of polyvinylidene fluoride and polymethyl methacrylate is known as an example of such a polymer. Of course, it is also possible to incorporate various inorganic filler additives, pigments, etc. that are commonly incorporated. The modified polymer or modified polymer composition constituting one layer of the laminate of the present invention is at least a portion of the ethylene polymer or the ethylene polymer composition containing the ethylene polymer as a main component. 5% or more by weight of vinyl acetate is graft copolymerized with respect to the polymer or polymer composition, and the total vinyl acetate content is 20 to 80% by weight, preferably 25 to 65% by weight. belongs to. Vinyl acetate can also be graft copolymerized in the coexistence of other copolymerizable vinyl monomers if necessary. This product may be used as long as it does not impede the effects of the present invention.
It is also possible to mix other polymers, inorganic fillers, stabilizers, coloring agents, and the like. As a specific embodiment, at least one polymer selected from ethylene polymers is grafted with an appropriate amount of vinyl acetate, or this is diluted with an ungrafted ethylene polymer or vinyl acetate polymer of the same or different type. The following applies. Here, the grafting method may be solution grafting, melt grafting, aqueous suspension grafting, or radiation grafting, but aqueous suspension grafting (for example, Japanese Patent Application No. 177645 (see specification) is preferred. If the amount of vinyl acetate grafted is less than the above amount, it is difficult to achieve the initial purpose due to the balance between adhesion and strength. Furthermore, if the total vinyl acetate content is less than 20% by weight, adhesion will be insufficient, and if it exceeds 80% by weight, moldability will deteriorate. This resin layer may also contain petroleum resins, tackifiers, etc. that are commonly used in hot melt adhesives. As a method for manufacturing the laminate of the present invention, a method of laminating the resins of both layers by coextrusion molding, press molding, extrusion lamination, etc. is used. Note that the laminate of the present invention includes not only these two layers, but also a laminate consisting of three or more layers including these two layers. At this time, other layers that can be used as a base material include, for example, polyvinyl chloride,
Halogen resins such as polyvinylidene chloride; Styrenic resins such as acrylonitrile-butadiene-styrene resin and polystyrene; Polyolefin resins such as polyethylene and polypropylene; Various rubbers such as acrylonitrile-butadiene rubber and styrene-butadiene rubber; metal;
Thermosetting resins such as unsaturated polyester, epoxy resin, and urethane resin; engineering resins such as thermoplastic polyester, polycarbonate, and nylon can be considered. The modified polymer or modified polymer composition constituting one layer of the laminate of the present invention can be laminated with these base materials without using an adhesive. Of course, it can also be attached with adhesive. At this time, when laminating with other base materials, it is necessary to ensure that the modified polymer or modified polymer composition used in the present invention contains unsaturated organic carboxylic acids or derivatives thereof, unsaturated organic carboxylic acids, unsaturated organic carboxylic acids, derivatives thereof, A part of the vinyl acetate in the ethylene polymer or vinyl acetate polymer that contains a glycidyl compound in the form of graft modification or copolymerization, or that constitutes the modified polymer or modified polymer composition, is hydrolyzed. A saponified product is preferred in terms of adhesiveness. Here, "contained in the form of graft modification or copolymerization"
means a method in which these unsaturated compounds are simultaneously grafted together with vinyl acetate during graft copolymerization of vinyl acetate, or an ethylene polymer that contains these unsaturated compounds in the form of graft or copolymerization in advance. a method of graft copolymerizing these unsaturated compounds to a modified polymer or modified polymer composition containing a predetermined amount of vinyl acetate; There is a method of kneading similar olefin polymers containing these unsaturated compounds in the form of gelaft modification or copolymerization. In addition, unsaturated carboxylic acid or its derivative is
Unsaturated compounds having carboxylic acid groups, acid anhydride groups, ester groups, carboxylic acid metal salts, carboxylic acid amide groups, etc. Examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, etc. and their derivatives. Maleic anhydride is particularly preferred. Examples of unsaturated glycidyl compounds include glycidyl methacrylate, glycidyl acrylate, and the like. Since the laminate of the present invention can also be obtained during molding of fluororesin, it is particularly useful for coating the inner surface of pipes such as metal pipes, which has conventionally been difficult to laminate. Next, examples will be shown, and each evaluation in the examples was based on the following method. (1) MFR: Compliant with JIS-K-6730. (2) Adhesion: After cutting the laminate into 1 cm wide strips and peeling off a portion, the fluororesin and base material were placed between the chucks of an Instron type testing machine and measured at a speed of 50 mm/min. . (3) Vinyl acetate content: Based on JIS-K-6730. Reference Example 1 20 kg of pure water, 0.6 kg of tribasic calcium phosphate as a suspending agent, and 0.06 kg of sodium dodecylbenzenesulfonate are mixed into a 50-capacity autoclave to form an aqueous solvent, and ethylene-based particles with a particle size of 3 to 4 mm are added to the aqueous solvent.
7 kg of vinyl acetate copolymer (MFR 30 g/10 minutes, vinyl acetate content 33% by weight) was added and stirred to suspend. Separately, 30 g of t-butyl peroxypivalate and 675 g of benzoyl peroxide were dissolved in 3 kg of vinyl acetate, and this was added to the suspension system. After introducing air into the autoclave and replacing the system, 0.5 kg of A pressure of /cm ² G was applied. Further, the temperature inside the autoclave was raised to 50°C, and the autoclave was left at this temperature for 5 hours with stirring to impregnate vinyl acetate containing a polymerization initiator into the ethylene-vinyl acetate copolymer particles. Next, this suspension was heated to 60°C and left at this temperature for 5 hours with stirring to polymerize.
The temperature was raised to 90°C and maintained for 5 hours to complete polymerization. After cooling, the solid contents were taken out and washed with water, and vinyl acetate modified ethylene-vinyl acetate copolymer particles 10
Got Kg. The vinyl acetate content in the obtained modified ethylene-vinyl acetate copolymer was 53% by weight. Example 1 Vinyl acetate modified ethylene obtained in Reference Example 1
A vinyl acetate copolymer and polyvinylidene fluoride (Kynar #460, manufactured by Pennwalt Co.) were each molded into a 0.5 mm thick sheet at 200° C. by compression molding. The obtained sheets were further laminated by compression molding at 200°C to obtain a laminated sheet of the modified ethylene-vinyl acetate copolymer and polyvinylidene fluoride. The adhesive strength between each layer of the obtained laminate was 2800g/
It was cm. Comparative Example 1 The ethylene-vinyl acetate copolymer shown in Table 1 and polyvinylidene fluoride were molded in the same manner as in Example 1 to obtain a laminate. The adhesive strength between each layer of the obtained laminate was as shown in Table 1.

[Table] Example 2 A modified ethylene-vinyl acetate copolymer into which 2-ethylhexyl acrylate was introduced as a copolymerizable monomer was obtained in the same manner as in Reference Example 1. The vinyl acetate content in the obtained modified ethylene-vinyl acetate copolymer was 44% by weight, and the 2-ethylhexyl acrylate content was 9% by weight. A laminate was obtained using this modified ethylene-vinyl acetate copolymer and polyvinylidene fluoride in the same manner as in Example 1. The adhesive strength between each layer of the obtained laminate was 3000g/
It was cm. Example 3 0.1 mm thick sheet of modified ethylene-vinyl acetate copolymer used in Example 1 and polyvinylidene fluoride
The 0.5 mm thick sheet and the 0.5 mm thick sheet of other base materials were molded by compression molding under the conditions shown in Table 2 to obtain a laminate. The adhesive strength between the modified ethylene-vinyl acetate copolymer and each layer of the obtained laminate was as shown in Table 2.

[Table] 〓
* Thermorun 3600 manufactured by Mitsubishi Yuka Co., Ltd.
Example 4 The modified ethylene-vinyl acetate copolymer used in Example 1 and the maleic anhydride-modified ethylene-vinyl acetate copolymer (MFR 4 g/10 min, vinyl acetate content 20
% by weight, maleic anhydride content 0.6% by weight) at a ratio of 80% by weight and 20% by weight, respectively.
The formulation was obtained through an extruder at 160°C. A 0.1 mm thick sheet of the obtained blended grapes, a 0.5 mm thick sheet of polyvinylidene fluoride, and other base materials were mixed into a third layer.
A laminate was obtained by compression molding under the conditions shown in the table. The composition of the obtained laminate and the adhesive strength between each layer were as shown in Table 3.

[Table] Comparative Example 2 The modified ethylene-vinyl acetate copolymer shown in Table 4 and polyvinylidene fluoride were molded in the same manner as in Example 1 to obtain a laminate. The adhesive strength between each layer of the obtained laminate was as shown in Table 4.

【table】

Claims (1)

[Claims] 1. A resinous modified resin containing at least a portion of an ethylene polymer grafted with vinyl acetate, the content of the grafted vinyl acetate being 5% by weight or more and the total vinyl acetate content being 20 to 80% by weight. 1. A laminate comprising a layer of a modified ethylene polymer or a modified ethylene polymer composition containing an ethylene polymer as a main component and a layer of a thermoplastic fluorine-containing resin.