JPS63286340A - Laminate of soft fluorine resin and rubber - Google Patents

Abstract

PURPOSE:To improve the adhesion of fluorine resin and generally used rubber by sticking a resin composed of specified fluorine resin to a generally used rubber through 4,4,4-triphenyl methane triisocyanate. CONSTITUTION:One kind or more monomer containing at least one kind monomer containing fluorine as fluorin resin is copolymerized with a monomer having simultaneously a double bond and a peroxy bond in a molecule, whereby the elastic copolymer containing fluorine whose glass transition temperature is under room temperature, is produced. It is obtained by graft copolymerizing one kind or more monomer containing at least one kind monomer containing fluorine providing the crystalline polymer having its melting point equal to 130 deg.C or higher in an aqueous emulsion of this copolymer or in a decomposition solvent. This fluorine resin film and the generally used rubber are stuck while effecting vulcanization of the rubber by a method in which unvulcanized rubber surface is directly coated with 4,4,4-triphenyl methane triisocyanate with NCO radical, and the film is lapped thereon, and them is pressed under heating.

Description

Detailed Description of the Invention (Field of application in the yrL business) The present invention provides chemical resistance, oil resistance, weather resistance, stain resistance,
The present invention relates to a fluororesin-rubber laminate that has improved chemical resistance, oil resistance, weather resistance, and stain resistance by coating a general-purpose rubber with a fluororesin having excellent flexibility.

(Prior art) Fluororesins have superior weather resistance, chemical resistance, stain resistance, etc. compared to other resins due to their chemical structural formula with large C-F bond energy, and are difficult to obtain with other resins. Due to its advantages, it is also applied to laminate products of fluororesin and rubber, and is used, for example, as a surface material for rubber conveyor belts due to its chemical resistance and stain resistance.

However, ordinary fluororesins have poor flexibility, so when used as a laminate with rubber, they have the disadvantage of impairing the elasticity of the rubber.

On the other hand, there are commercially available fluororubbers (FKM) with C-F bonds, but these are expensive, have problems with acid resistance such as hydrochloric acid and sulfuric acid, and require a vulcanization process after molding. There is.

In addition, from the viewpoint of adhesion technology between fluororesin and rubber, fluororesin has excellent non-adhesive properties due to its structure, so special surface treatments such as corona discharge treatment or chemical treatment that modifies the fluororesin surface with a sodium-containing reagent can be applied. A common technique is to bond fluororesin and rubber by performing a treatment.

(Problems to be Solved by the Invention) In the development of a fluororesin-rubber laminate, the present invention uses a fluororesin to improve the weather resistance, chemical resistance, oil resistance, stain resistance, etc. required for a rubber laminate. The object of the present invention is to provide a flexible fluororesin-rubber laminate that maintains excellent characteristics and also enables adhesion between a flexible fluororesin and rubber that is not as bad as conventional fluororesins.

(Means for solving the problem) The present inventors have disclosed in Japanese Patent Application Laid-Open No. 58-206615, “
This invention relates to a method for producing a flexible fluororesin.

This resin (hereinafter referred to as the fluororesin) has a chemical structure that has never been seen before in the category of fluororesins. It is a graft copolymer having a chemical structure obtained by graft polymerization of a vinyl monomer that gives

In other words, the fluororesin is made by copolymerizing one or more monomers including one kind of fluorine-containing monomer and a monomer having both a double bond and a peroxy bond in the molecule. The first step is to produce a fluorine-containing elastic copolymer that contains peroxy groups in its molecules and whose glass transition temperature is below room temperature, and in the second step, Graft copolymerization of one or more monomers containing at least one fluorine-containing monomer that yields a crystalline polymer whose melting point is 130° C. or higher in an aqueous emulsion of the copolymer or a dispersion solvent. It is a flexible fluororesin obtained by

In the present invention, by using the fluororesin and adhering the resin and general-purpose rubber via 4.4.4-) liphenylmethane triisocyanate, the elasticity of the general-purpose rubber is not impaired and the weather resistance is improved. We have developed a flexible fluororesin-rubber laminate that maintains properties, chemical resistance, and oil resistance.The adhesive used here has the general formula 0ON''/C.
)-0H-C5-Wo.

It is a 4,4.4-) triphenylmethane triisocyanate represented by the formula, and there are no particular restrictions on how it can be used.

General-purpose rubbers include butadiene, acrylonitrile rubber (NBR), cloprene rubber (CR), and butadiene rubber.
Various synthetic rubbers such as styrene rubber (SBR), butyl rubber (IIR), ethylene propylene rubber (EPDM), etc. can be widely used. These general-purpose rubbers are characterized by exhibiting rubber elasticity, and are particularly excellent in impact resilience.

These general-purpose rubbers are used depending on the application, depending on their price and performance such as weather resistance, chemical resistance, mechanical strength, electrical properties, hardness, and operating temperature.
Each type of rubber is used for tires, tubes, belts, hoses, packing, electric wires, etc., taking into consideration its performance, price advantages, and disadvantages, and the laminate of the present invention takes advantage of the characteristics of these general-purpose rubbers. It can be used without any damage.

As an example of the fluororesin, as described in Examples below, a backbone polymer is obtained by copolymerizing monomer compositions (vinylidene fluoride, chlorotrifluoroethylene, t-butylperoxyallyl carbonate), and fluorine is added to this backbone polymer. The fluororesin is obtained by graft polymerizing vinylidene chloride.

The melting point of the fluororesin in this composition is 155-165
Films, sheets and other shapes are easily formed by extrusion using a T-die at .degree.

One physical property of the obtained film is that the tensile strength is 200 at 25°C.
kP, f/cIA, elongation at break of 410%, Izot impact strength of 50ksr-all/c11 or more, and scum permeability is low.

In addition, in the accelerated weather resistance test of the fluororesin using a Sunshine Weatherometer, the tensile strength retention after 5000 hours was 90%, and the tensile strength retention was 100% - modulus retention was 103.
% and exhibits excellent weather resistance. Furthermore, since the gas permeability of the film is extremely low, the laminate will not be corroded by gas and the adhesive surface will not peel. In addition, in chemical resistance tests, especially hydrochloric acid, sulfuric acid, hydrofluoric acid, hydroxide)
It has excellent corrosion resistance against chemicals such as ethanol and carbon tetrachloride.

A major feature of the fluororesin-rubber laminate of the present invention is that it overcomes the problems of conventional fluororesins, which are hard, impair the elasticity of the rubber, and are difficult to bond.

This flexibility is due to the chemical structure of the soft fluororesin, and in particular, the backbone polymer in the fluororesin is
Since it is composed of a fluorine-containing copolymer whose glass transition temperature is below room temperature, it exhibits the properties of a rubber elastic body at temperatures above room temperature, and as a result becomes flexible.

The fluororesin-rubber laminate of the present invention can be formed into a film having a thickness of usually about 50 microns to about 3% by extrusion molding using a T-die using the fluororesin.

The adhesion between the obtained fluororesin film and general-purpose rubber is performed before the various general-purpose rubbers are vulcanized and molded.・4,4.4-) liphenylmethane triisocyanate having -NGO groups on the surface of unvulcanized rubber (For example, Desmosier R manufactured by Bayer AG) is applied directly, the film is overlaid on top of the film, and the rubber is vulcanized using heat press to form a strong laminate of the fluororesin and rubber in an extremely efficient manner. You can get a good deal.

On the other hand, adhesives other than 4.4.4-triphenylmethane triisocyanate have weak adhesive strength, and even when conventional fluororesin surface modification methods such as corona discharge treatment and chemical treatment are applied, the adhesive strength remains low. As a result of the test, it was found that it is difficult to bond the soft fluororesin and rubber well using the conventional fluororesin surface modification method.

Additionally, epoxies, chloroprene/phenolics, polyurethane adhesives, and common polyisocyanates
Tris-4 phenyl incyanate thiophosphate (manufactured by Bayer AG, trade name: Desmodur I?F) having an NGO group was also tested, but the adhesion was not good.

The present invention will be described in detail below with reference to Examples, but it is not limited thereto.

Examples 1 to 5 Examples of manufacturing a fluororesin and a film thereof used to prepare a specimen of the present invention will be described.

100I! Pure water in a stainless steel autoclave with a capacity of 5
Add 0 kg of potassium persulfate, 100 g of ammonium perfluorooctanoate, and 100 g of t-butyl peroxyallyl carbonate, and after evacuation, add +r to 12.5 kg of vinylidene fluoride monomer and 7.55 kg of chlorotrifluoroethylene monomer, and heat at 50°C while stirring. The polymerization reaction was carried out at a temperature of 20 hours.

The product was obtained in the form of a white latex, which was salted out to obtain rubbery particles. After washing with water and vacuum drying, the product was washed with n-hexane to remove unreacted t-butylperoxyallyl carbonate, and vacuum-dried again to obtain +r as a white powder copolymer 16. The DSC curve of this copolymer is based on the decomposition of peroxy groups (exothermic peak is 160-1
The copolymer was kept at 80°C, and the amount of active oxygen in the copolymer was determined to be 0.042% by iodometric titration.

In the next step, 12 kg of the white powder copolymer and Freon R-11375ksr were added to withstand a pressure of 100 atm.
In addition to a stainless steel autoclave with a capacity of
Time polymerization was performed.

The produced polymer was separated from the solvent and dried to obtain 16.6-white powder. The melting point of this polymer was determined to be 155-160°C by DSC measurement.

Next, using the fluororesin as a raw material, a 30% extruder (L/D-22, screw rotation speed 20 rpys
The fluororesin film with a thickness of 200 μm was molded using an extruder molding temperature (Cs: 190°C, C: 200°C, Cm: 210°C, H: 220°C, D-22
It was molded under conditions (0°C) and used as a film for preparing a specimen.

The general-purpose rubber to be laminated with the fluororesin film is unvulcanized rubber before heat-pressure molding, and its types include CR55BRSIIR, EP as shown in Table 1.
DM and NBR were used. A thin layer of Desmosier R (manufactured by Bayer AG) having an isocyanate-NGO group is directly applied to the adhesion surface of these general-purpose rubbers at a coating rate of 10 to 50 g/rd. Laminate a 200 μm thick fluororesin film on the coated surface, sandwich it between metal plates, and heat press at 150°C +50 to 120°C.
-.f/d pressure was applied and this state was continued for 30 minutes to simultaneously perform vulcanization. After that, 30 to 120 pieces in a cooling press.
A fluororesin-rubber laminate was prepared by cooling at a pressure of
Difficult adhesive strength was measured. The results are shown in Table 1.

Comparative Examples 1 to 12 As Comparative Examples, among the fluororesin film/unvulcanized CR laminates, untreated, corona discharge treated, chemical treated, and film were used to measure the adhesive strength without adhesive. In Comparative Example 4, the conventionally used fluororesin FEP
The adhesion strength was measured and compared. Furthermore, comparative example 5~
lO is the untreated fluororesin, film/unvulcanized CR
The adhesion strength when epoxy adhesive, CR-phenol adhesive, polyurethane adhesive, Desmosier RF, and Coronate L were applied as adhesives in the laminate of The adhesive strength between the sample and Desmosier R was measured. The result is the first
Also listed in the table.

(Effect of the invention) From the above Examples and Comparative Examples, even if the fluororesin film was subjected to corona discharge and chemical treatment, the adhesive strength with general-purpose rubber was low. By directly applying Desmodur R and applying heat and pressure, the adhesion performance between the fluororesin and general-purpose Go A was significantly improved by 10 to 20 times.

Furthermore, the types of general-purpose rubber are not only CR, but also NBR, 5
BRSIIR and EPDM are also recognized to be effective, and are recognized to be effective not only for specific rubbers but for many rubbers.
The obtained laminate can be used as a surface material for packing, tubes, hoses, or conveyor belts without impairing its rubber elasticity (
Can be used.

Claims (1)

[Claims] One or more monomers containing at least one fluorine-containing monomer and a monomer having both a double bond and a peroxy bond in the molecule are copolymerized, and the glass transition temperature thereof is below room temperature. A fluorine-containing elastic copolymer (stem polymer) is produced, and one or more monomers containing at least one fluorine-containing monomer that give a polymer with a melting point of 130° C. or higher are graft copolymerized to the backbone polymer. Using a soft fluororesin, the soft fluororesin and general-purpose rubber,
A soft fluororesin/rubber laminate characterized by using 4,4,4-triphenylmethane triisocyanate as an adhesive and molding under heat and pressure.