MXPA98007694A

MXPA98007694A - Product estratific

Info

Publication number: MXPA98007694A
Application number: MXPA/A/1998/007694A
Authority: MX
Inventors: Bladel Hermann; Grossmann Gerd; Dadalas Michael
Original assignee: Dyneon Gmbh 84508 Burgkirchen De
Priority date: 1996-03-22
Filing date: 1998-09-21
Publication date: 1999-04-06

Abstract

Leaf-shaped structures consisting of rubber layers and fluoropolymer layers are produced by using, as an adhesive layer, a mixture consisting of rubber and a thermoplastic fluoropolymer having a melting point < 250

Description

STRATIFIED PRODUCT DESCRIPTIVE MEMORY Configured and covered items made of natural and synthetic rubber are widely used in the industry. A disadvantage of these materials is their relatively low resistance to aggressive chemical compounds, in particular at elevated temperatures. Therefore, there have been attempts to coat the rubber with the much more highly resistant fluoropolymers. However, these attempts failed because conventional bonding and vulcanization procedures did not allow a sufficiently strong bonding of the fluoropolymer. Nor have there been attempts to employ fluorinated thermoplastics for this purpose, in particular tetrafluoroethylene copolymers with amounts of comonomers such that the product is processable from the molten bath. However, even these copolymers, which in their properties approximate the elastomers, do not adhere to the rubbers. Surprisingly, it has now been found that excellent adhesion can be produced between the rubbers and fluoropolymers when a formulation comprising a rubber and from 10 to 70% by weight of a thermoplastic fluoropolyol having more than about 35% is employed as a first layer. by weight of tetrafluoroethylene units and also units of hexafluoropropene and vinylidene fluoride having a melting point of < 250 ° C. Additional aspects and particular embodiments of the invention are explained in greater detail in the claims. Therefore, the invention relates to a composition consisting essentially of a rubber and the thermoplastic fluoropolymer as described. The terpolymers of tetrafluoroethylene, hexafluoropropene and vinylidene fluoride have thermoplastic properties. if they contain more than about 35% by weight of tetrafluoroethylene. Such terpolymers are known, for example, from US Pat. No. 4,335,238 and from DE-A 26 35 402 (AU-A 76/16635). Suitable terpolymers comprise from about 40 to about 60% by weight of tetrafluoroethylene, from about 10 to about 40% by weight of hexafluoropropene and from about 10 to about 40% by weight of vinylidene fluoride. EP-A-0 428 158 relates to a vulcanizable polymer composition made of a crosslinkable hydrocarbon elastomer, a polymer based on vinylidene fluoride and a crosslinking agent. After vulcanization, it can be used to produce a packing material of resistance to chemical compounds and increased heat. A copolymer made of vinylidene fluoride, tetrafluoroethylene and hexafluoropropene, among others, is included in the aforementioned vinylidene fluoride copolymers. US-A-4 942 906 refers to a rubber hose with an outer rubber layer and an internal rubber layer, the inner layer being composed of two layers. The layer on the inside is formed of a first polymer mixture made of acrylic rubber and of a fluorine-containing resin, and the outer layer being formed of a second polymer mixture which differs from the first polymer mixture and which comprises a epichlorohydrin rubber. The listed fluorine-containing resins are homopolymers and copolymers of tetrafluoroethylene-hexafluoroethylene, and also ethylene-tetrafluoroethylene copolymers but not terpolymers. US-A-4 041 207 discloses a heat-resistant rubber laminate material consisting essentially of a rubber layer made of a heat-resistant rubber mixture and a heat-resistant outer layer made essentially of ethylene-fluoropropylene elastomer. Therefore, the novel composition is attached on one side to the rubber and on the other to the fluoropolymer (a layer thereof) as described. This fluoropolymer in turn binds to layers of other fluoropolymers. In this manner, laminated products of many different types can be produced, comprising layers of rubber and fluoropolymers and therefore combining the properties of these two kinds of materials. The fluoropolymers can be mixtures of copolymers of identical type. It is advantageous to use uniform fluoropolymers. In one aspect, the invention relates to a layered product that includes a fluoropolymer layer and a rubber. A stratified product of this type, for example, can be constructed in the following manner: a) A top layer consisting essentially of the fluoropolymer, and b) The layer that was described, consisting essentially of a rubber mixture and the fluoropolymer. The layer (a) can be attached to a layer of a fluoropolymer, that is, a layered product of this type is an intermediate for mixed articles. This intermediate, through layer (b), can be joined to one or more layers of rubber bonded by vulcanization. Furthermore, the invention relates to stratified products in which both outer sides comprise a fluoropolymer, whereby a rubber layer is present only in the interior. One skilled in the art can contemplate further embodiments of this principle in accordance with the respective requirements, depending for example on whether the fluoropolymer acting as an adhesion promoter satisfies the requirements for the external side or if another fluoropolymer is to be used as the side external. The amount of fluoropolymer layer (b) may vary within various limits and is usually in the range of 10 to 70% by weight, preferably 20 to 50% by weight. Suitable oils, as mentioned, are types of natural and synthetic rubber, that is, in addition to natural rubber, conventional synthetic rubbers based on butadiene, butadiene-acrylonitrile, butadiene-styrene, chloroprene, isoprene, isobutene, ethylene-propylene, ethylene - vinyl acetate, acrylate and epichlorohydrin, butyl rubber, chlorobutyl, bromobutyl, polysulfide, urethane, fluorine and silicone, chlorinated and chlorosulfonated polyethylene and hydrogenated acrylonitrile-butadiene rubber. The novel layered products can be produced by mixing a rubber with the fluoropolymer or by incorporating a component in the other, for example by kneading, then producing a sheet or three-dimensional structure from this mixture, vulcanizing it, if desired with a rubber layer, and then applying the fluoropolymer to at least one layer and fixing it. The fluoropolymer can be applied by conventional methods such as powder, in the form of a film, molten bath or as a liquid formulation, for example, as a solution or dispersion.

The following materials were used: a) A terpolymer consisting of: 42% of tetrafluoroethylene units, 20% of hexafluoropropene and 38% of vinylidene fluoride units and b) A butyl-rubber mixture consisting of 100 parts of rubber, 100 parts of carbon black and 100 parts of filler (mainly kaolin). Rubber is soluble in petroleum and vulcanized at 143 ° C.

EMOTION 1 A mixture of 80% rubber mixture and 20% terpolymer is prepared and vulcanized in several layers. The layers show very good adhesion.

EXAMPLE 2 A mixture as in Example 1 is converted to a layer and vulcanized with a layer consisting only of the rubber mixture. Again, the layer shows very good adhesion after vulcanization, that is, the layer containing the terpolymer imparts very good adhesion to the layer of the rubber mixture. Using the layer comprising the terpolymer, the layered product thus obtained can be treated in a separate step with a fluoropolymer layer.

EXAMPLE 3 A mixed material is produced as in Example 5, and a solution of the terpolymer in methyl ethyl ketone is applied to the layer containing the terpolymer, and the solvent is evaporated. A film of a second terpolymer of the following composition is applied to the thus obtained and vulcanized surface coating layer: 57% of tetrafluoroethylene units, 30% of hexafluoropropene units and 13% of ethylene units. A mixed material is obtained that has good adhesion.

Claims

NOVELTY OF THE INVENTION CLAIMS

1. - A composition consisting essentially of a rubber and from 10 to 70% by weight of a thermoplastic fluoropolymer having more than about 35% by weight of tetrafluoroethylene units and also units of hexafluoropropene and vinylidene fluoride having a melting point < 250 ° C.

2. A composition according to claim 1, further characterized in that the content of fluoropolymer is 20 to 50% by weight.

3. A stratified product including a layer of a composition according to claim 1.

4. A stratified product according to claim 3, further characterized in that the layer is attached to a rubber layer.

5. A stratified product according to claim 3, further characterized in that the layer is attached to a fluoropolymer layer.

6. A stratified product consisting essentially of a rubber layer, joined on both sides to a layer according to claim 3 wherein, if desired, one of the outer layers is (are) attached to a layer of the fluoropolymer and, if desired, one or both of these fluoropolymer layers are (are) bonded to an additional layer of another fluoropolymer. 1 .

A stratified product according to claim 3, further characterized in that the layer is attached on one side to a rubber layer and on the other to a fluoropolymer layer which, if desired, is bonded to a layer of another fluoropolymer.

8. A process for producing a layered product according to one or more of claims 3 to 7, which comprises mixing a thermoplastic terpolymer having more than about 35% by weight of tetrafluoroethylene units, hexafluoropropene and fluoride units. vinylidene and a melting point < 250 ° C with a rubber, this mixture containing 10 170% by weight of the fluoropolymer, producing from the mixture a leaf-shaped structure or a three-dimensional article, if desired vulcanizing it together with an additional layer of rubber, applying the fluoropolymer to the article thus formed on at least one side of which contains the fluoropolymer, heat fixing this applied layer and if desired, applying an additional fluoropolymer layer to the fluoropolymer layer (s) (each) and fixing it.

9. A method for using a composition according to claim 1 or 2, for bonding the rubber and the fluoropolymer and, if desired, an additional fluoropolymer or for bonding rubber layers.

10. - A method for using a layered product according to claims 3 to 7 or a layered product obtained according to claim 8, in the construction of chemical equipment.