JPH0578497A - Production of ptfe polymer alloy - Google Patents

Abstract

PURPOSE:To provide a PTFE polymer alloy capable of being largely improved in the mechanical strength. CONSTITUTION:An alloy polymer comprising PTFE and one kind or more of other polymers is subjected to a wetting treatment using a fluorine-based high boiling point inert liquid, and the wet polymer blend is charged in the fluorine-based high boiling point inert liquid heated to >=170 deg.C, and the fluorine- based random copolymer is dissolved in the liquid to obtain a PTFE polymer alloy. The 1:1 alternating copolymer of vinylidene fluoride and hexafluoroisobutylene is preferable as the different kind of the polymer for the production of the polymer alloy, and the copolymer of tetrafluoroethylene and perfluoro(2,2-dimethyl-1,3-dioxazole) is preferable as the fluorine-based random copolymer used for accelerating the solubility of the PTFE.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polymer alloy, and more particularly to a polymer alloy in which one polymer is PTFE.
The present invention relates to a method for producing a TFE polymer alloy.

[0002]

2. Description of the Related Art PTFE (polytetrafluoroethylene) is heat resistant, harmless to human body, chemically resistant,
Furthermore, it has excellent self-lubricating properties and has a wide range of application fields such as anti-kogation surface treatment, liquid leakage prevention, stuffiness prevention apparel, artificial blood vessels, and separation membranes.

[0003]

[Problems to be Solved by the Invention] By the way, PTFE
Has relatively low mechanical strength, especially compressive strength. For this reason, when PTFE alone or a PTFE porous body is used as a thin material, the drawback becomes remarkable.

Polymer alloying can be considered as a technique which has recently been rapidly developed as a method for improving the drawbacks of the PTFE alone. However, since PTFE has no fluidity even when melted, and because of its peculiarity that it is not soluble in a solvent, the polymer alloying of PTFE is greatly restricted. In particular, a method in which two or more kinds of polymers constituting an alloy are dissolved in their common solvent and then only the solvent is removed by an appropriate method to form an alloy, the dimension of phase separation is extremely small. It is the best way to obtain a useful alloy because it is possible, but as mentioned above, the problem of insolubility of PTFE is a major technical obstacle to alloying.

It is an object of the present invention to provide a method for producing a PTFE-based polymer alloy which solves the above-mentioned problems of the prior art and makes it possible to greatly improve the mechanical strength.

[0006]

In order to achieve the above object, the present invention solves the above-mentioned problems by dissolving two or more alloy polymers constituting an alloy in their common solvent and then evaporating the solvent to obtain a PTFE-based polymer alloy. In the method for producing, the alloy polymer is composed of PTFE and at least one polymer, the polymers are wet-treated with a fluorine-based high-boiling inert liquid, and then the wet blend system is heated to 170 ° C. or higher. It is a liquid which is dropped into a fluorine-based high boiling point inert liquid, and a fluorine-based random copolymer is dissolved in the fluorine-based high boiling point inert liquid.

That is, according to the present invention, a fluorine-based high boiling point inert liquid is used as a solvent for PTFE, a wet treatment is incorporated into PTFE in advance, and the fluorine-based high boiling point inert liquid as a solvent is heated to 170 ° C. or higher. It is due to the fact that it was heated and that the fluorine-based random copolymer was used to accelerate the dissolution of PTFE, and it is possible to produce a PTFE-based polymer alloy with greatly improved mechanical strength due to the overall action of them. Become.

Suitable as the PTFE used in the present invention is a fine powder for paste extrusion separated and granulated from a dispersion produced by emulsion polymerization. Further, a homopolymer is preferable, but a modified PTFE obtained by copolymerizing different kinds of monomers within 3 mol% may be used in order to improve processability.

As a different polymer for producing a polymer alloy for improving the mechanical strength of PTFE, a 1: 1 alternating copolymer of vinylidene fluoride and hexafluoroisobutylene (trade name; CM-X, product of Enimont), ETF
E (tetrafluoroethylene / ethylene copolymer), P
VdF (polyvinylidene fluoride) and the like,
Of these, CM-X is most suitable. Since the above-mentioned polymer shapes are required to be dissolved in a solvent, pellets suitable for ordinary molding are unsuitable, and powders having a shape immediately after synthesis are most suitable.

As the solvent used as the common solvent,
What is generally known as a fluorine-based inert liquid (trade name; Fluorinert, product of 3M Company) is suitable, and it has been found through experiments that Fluorinert having a boiling point of 170 ° C. or higher is the most suitable. This fluorine-based high-boiling-point inert liquid is also used for the wet treatment of PTFE, and the liquid used for the wet treatment and the liquid heated to a temperature of 170 ° C. or higher may be the same liquid or similar liquids.

The fluorine-based random copolymer used for promoting the solubility of PTFE in the present invention includes:
Tetrafluoroethylene and PDD [Perfluoro (2,
2-dimethyl-1,3-dioxole)] (trade name; Teflon AF, a product of DuPont). This fluorine-based random copolymer may be dissolved in advance in a fluorine-based high boiling point inert liquid heated to 170 ° C. or higher, and a fluorine-based polymer at a temperature of 170 ° C. or higher in which a wet blend system such as PTFE is charged. It may be dissolved in a boiling point inert liquid.

[0012]

EXAMPLES Examples of the present invention will be described below.

(Example) Polyflon TF as PTFE
5.5 g of EF-104, a 1: 1 alternating copolymer of vinylidene fluoride and hexafluoroisobutylene (trade name;
4.5 g of CM-X) is weighed, placed in a 200 ml wide-mouth glass bottle, shaken, and mixed well. next,
To this system, adequate amount of Fluorinert FC-70 (bp 215 ° C.) for wetting the whole was appropriately added, and further shaken and sufficiently mixed, and then allowed to stand at room temperature for 24 hours (wetting treatment). .

On the other hand, a 300 ml separable flask is set with a stirrer, a thermometer, and a reflux tube, and 150 ml of Fluorinert FC-70 is put into this and heated to 170 ° C.
This temperature is arbitrary up to the boiling point of 215 ° C. for the effect of the experiment, but it is required to be 170 ° C. or higher. Further, since this fluorinate generates PFIB (perfluoroisobutylene), hydrogen fluoride, etc., which are harmful to the human body, near the boiling point, a temperature lower than the boiling point is desirable. However, if it is done under sufficient ventilation, it will not be a problem.

Next, the flask is heated to 170 ° C.
Approximately 10 g of the PTFE / CM-X blend which has been subjected to the above-mentioned wet treatment into the stirred Fluorinert FC-70.
Throw in.

As a result, the PTFE / CM-X blend forms a weak gel in the flask. The substance of this gel is an aggregate of PTFE fibrils and CM-X dispersed therein.

Next, Teflon AF1600 (T
g 160 ° C.), 3 g (about 1%) is added, and the mixture is stirred for 1 hour. This causes the blend to dissolve into the Fluorinert.

Then, a distillation apparatus is set on the upper part of the flask to evaporate the fluorinate. Then, when about 50 ml of Fluorinert was removed, PTF
An alloy of E / CM-X / Teflon AF1600 is solidified and produced.

This coagulated PTFE-based polymer alloy was added to 200
A 2 mm pressed sheet was prepared by hot pressing at 10 ° C. for 10 minutes, and the Shore hardness of this sheet was measured at room temperature. As a result, 7 compared to 49 when using PTFE alone
A remarkable improvement in Shore hardness of 8 was observed.

(Comparative Example) The same experiment as the above example
The temperature of Fluorinert FC-70 in the flask was set to 150 ° C.
However, weak gelation (fibrillation) of the PTFE / CM-X blend did not occur. In this case, even if Teflon AF1600 was added in exactly the same amount and stirred, the PTFE / CM-X blend did not dissolve.

[0021]

In summary, according to the present invention, the PTFE
And at least one polymer are wet-treated with a fluorine-based high-boiling inert liquid, and then the wet blend system is dropped into a fluorine-based high-boiling inert liquid heated to 170 ° C. or higher and the fluorine-based high-boiling inert liquid is added. Dissolving the fluorine-based random copolymer in the boiling point-inert liquid exerts an excellent effect that a PTFE-based polymer alloy having significantly improved mechanical strength can be produced.

Claims (1)

[Claims] 1. A method for producing a PTFE-based polymer alloy obtained by dissolving two or more alloy polymers constituting an alloy in a common solvent thereof, and then evaporating the solvent, wherein the alloy polymer is PTFE and at least one polymer. Wet these polymers with a fluorine-based high-boiling inert liquid, then drop the wet blend system into the fluorine-based high-boiling inert liquid heated to 170 ° C or higher, and A method for producing a PTFE-based polymer alloy, which comprises dissolving a fluorine-based random copolymer in an inert liquid having a boiling point.