JPH0376217B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminate having a layer of thermoplastic fluororesin (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 (PTFE) is a representative polymer of this fluororesin, and because of its high heat resistance and excellent solvent resistance, it is used as internal corrosion protection and packing for piping in chemical equipment, and because of 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, PTFE can be molded using fluorine-containing unsaturated monomers other than tetrafluoroethylene, copolymers with tetrafluoroethylene using other unsaturated monomers, or fluororesins without tetrafluoroethylene. With improved properties, it has become possible to obtain thermoplastic materials with the properties of PTFE. 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 fluororesin and ethylene-ethyl acrylate copolymer disclosed in No. 56-86748 and No. 57-12645, a large amount of ethyl acrylate is copolymerized with ethylene to improve adhesion. Introducing the copolymer in this manner is undesirable because it has the disadvantage that the mechanical strength of the copolymer decreases and the adhesive strength is not significantly improved. The present invention was made with the aim of improving these drawbacks, and it was discovered 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 an alkyl acrylate, and the content of the grafted alkyl acrylate is 5% by weight or more and the content of the total alkyl acrylate 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 fluororesin. 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, hexene-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, Suitable are copolymers with ethyl acrylate, methyl methacrylate, maleic acid, itaconic acid, maleic anhydride, etc., or processed products of these polymers by oxidation, chlorination, saponification, etc.
Here, the copolymer may be in random, block, or graft form; however, in the case of a copolymer of ethylene and alkyl acrylate, a copolymer that is not in the form of graft is used. Specific examples of ethylene polymers include low, medium, and high density polyethylene, ethylene-propylene copolymer, and ethylene-propylene copolymer.
Examples include butene copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, maleic anhydride grafted polyethylenes, and those with a crystallinity of 50% or less are preferred. Among them, ethylene-alkyl acrylate copolymer is preferred,
In particular, an ethylene-alkyl acrylate copolymer having an alkyl acrylate content of 15% by weight or more is preferred. Alkyl acrylates include methyl, ethyl, propyl acrylic acid or methacrylic acid,
Examples include butyl ester, but methyl or ethyl ester is preferred from the viewpoint of adhesiveness. 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, it is also possible to use a blend of other polymers that are compatible with the fluororesin, 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 of alkyl acrylate is graft copolymerized with respect to the polymer or polymer composition, and the total alkyl acrylate content is 20 to 80% by weight, preferably 25 to 65% by weight. belongs to. The alkyl acrylate 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.
Other polymers, inorganic fillers, stabilizers, colorants, etc. can be mixed in and used. As a specific embodiment, at least one polymer selected from ethylene polymers is grafted with an appropriate amount of alkyl acrylate, or this is diluted with an ungrafted ethylene polymer or alkyl acrylate 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; (see specification) is preferred. If the amount of alkyl acrylate grafted is less than the above-mentioned amount, it is difficult to achieve the initial objective due to the balance between adhesiveness and strength. Furthermore, if the total alkyl acrylate content is less than 20% by weight, the adhesion will be insufficient, and if it exceeds 80% by weight, the moldability will be poor. 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; aluminum, iron, etc. metals; thermosetting resins such as unsaturated polyesters, epoxy resins, and urethane resins; engineering resins such as thermoplastic polyesters, polycarbonates, and nylons. 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, in laminating with other base materials, the modified polymer or modified polymer composition used in the present invention, in addition to containing the above-mentioned alkyl acrylate, unsaturated organic carboxylic acid or its derivative, unsaturated glycidyl Those containing the compound in the form of graft modification or copolymerization are preferred from the viewpoint of adhesive properties. Here, "contained in the form of graft modification or copolymerization"
This refers to a method in which these unsaturated compounds are simultaneously grafted together with the alkyl acrylate when alkyl acrylate is graft copolymerized, 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 alkyl acrylate; a method of graft copolymerizing these unsaturated compounds to a modified polymer or modified polymer composition; There is a method of kneading olefin polymers similar to those described above that contain these unsaturated compounds in the form of graft 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 strips 1 cm wide and peeling off a portion, the fluororesin and base material were placed between the chucks of an Instron type testing machine and tested at a speed of 50 mm/cm.
Measured in minutes. (3) Alkyl acrylate content: Determined by infrared analysis after vacuum drying the obtained modified polymer at 60°C for 10 hours. Reference Example 1 20 kg of pure water, 0.6 kg of tribasic calcium phosphate as a suspending agent, and 0.6 g of sodium dodecylbenzenesulfonate are mixed in a 50-capacity autoclave to form an aqueous medium, and ethylene-
Add 7 kg of ethyl acrylate copolymer (MFR 20 g/10 minutes ethyl acrylate content 18% by weight),
Stir to suspend. Separately, 30 g of t-butylperoxy(2-ethylhexanoate) was dissolved in 3 kg of ethyl acrylate, and this was added to the suspension system, and nitrogen was introduced into the autoclave to replace the inside of the system. Furthermore, the temperature inside the autoclave was raised to 60℃, and it was left at this temperature for 5 hours with stirring to remove ethyl acrylate containing a polymerization initiator, etc.
It was impregnated into ethyl acrylate copolymer particles. Next, the temperature of this suspension was raised to 80°C, and the polymerization was carried out by leaving it at this temperature for 5 hours while stirring.
The temperature was raised to 90°C and maintained for 3 hours to complete polymerization. After cooling, the solid contents were taken out and washed with water to obtain 10 kg of ethyl acrylate-modified ethylene-ethyl acrylate copolymer particles. The ethyl acrylate content in the obtained modified ethylene-ethyl acrylate copolymer was 43% by weight. Example 1 The ethyl acrylate-modified ethylene-ethyl acrylate copolymer obtained in Reference Example 1 and polyvinylidene fluoride (Kynar # manufactured by Pennwalt Co., Ltd.
460) and 0.5mm each at 200℃ using compression molding method.
A thick sheet was formed. The obtained sheets were further laminated by compression molding at 200°C to obtain a laminated sheet of the modified ethylene-ethyl acrylate copolymer and polyvinylidene fluoride. The adhesive strength between each layer of the obtained laminate was 1120g/
It was cm. Comparative Example 1 The ethylene-ethyl acrylate 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 laminate was obtained in the same manner as in Example 1 using the modified ethylene-ethyl acrylate copolymer used in Example 1 and polyvinylidene fluoride (Kynar #1120). The adhesive strength between each layer of the obtained laminate was 1060g/
It was cm. Example 3 Modified ethylene-ethyl acrylate copolymer used in Example 1 and maleic anhydride-modified ethylene-
Ethyl acrylate copolymer (MFR6g/10min,
(ethyl acrylate content: 18% by weight, maleic anhydride content: 0.6% by weight)) were blended at a ratio of 80% by weight and 20% by weight, respectively, and passed through an extruder at 160°C to obtain a blend. A 0.1 mm thick sheet of the obtained blend, a 0.5 mm thick sheet of polyvinylidene fluoride, and other base materials were mixed into a second 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 2.

【table】

Claims (1)

[Claims] 1 Contains at least a portion of an ethylene polymer graft-copolymerized with an alkyl acrylate, the content of the grafted alkyl acrylate is 5% by weight or more, and the content of the total alkyl acrylate is 20% by weight or more.
A laminate 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 fluororesin in an amount of ~80% by weight. .