JPS5941352A - Improved fluorine-containing thermoplastic rubber composition - Google Patents

Abstract

PURPOSE:To prepare the titled composition having improved mold releasability, sizability and permanent compression set, by adding silicic acid and/or its salt to the base rubber. CONSTITUTION:A fluorine-containing thermoplastic rubber is compounded with silicic acid and/or its salt. The fluorine-containing thermoplastic rubber is preferably composed of 40-95pts.wt. of at least one kind of elastomeric polymer chain segment and 5-60pts.wt. of at least one kind of non-elastomeric polymer chain segment, wherein at least one of the segments is fluorine-containing polymer chain segment. The rubber may be incorporated with a vulcanizing agent. The silicic acid and/or its salt is preferably silicic acid, and its amount is 2- 50pts.wt., preferably 5-30pts.wt. per 100pts.wt. of the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved fluorinated thermoplastic rubber composition, and more specifically, by incorporating silicic acid and/or its salt, mold releasability, sizing property, and compression set are improved. The present invention relates to a fluorine-containing thermoplastic rubber composition with improved properties.

Fluorine-containing thermoplastic rubber has excellent heat resistance, abrasion resistance, chemical resistance, solvent resistance, oil resistance, etc., and is used for tubes, sheets, films, and other molded products (e.g. O-rings,
It is used for a variety of purposes by being molded into a seal or covered with electric wires, exterior materials, fasteners, etc.

However, fluorine-containing thermoplastic rubber sticks to molds and rolls during molding and rolling, and its releasability cannot be determined. Furthermore, the sizing properties are not sufficient. moreover,
Some types of rubber have poor compression set and stress fracture resistance.

The present inventors conducted research in order to improve these drawbacks of fluorine-containing thermoplastic rubber without impairing its other excellent properties. The present inventors have discovered that by blending the salt, it is possible to improve the mold releasability and sizing properties of highly fluorinated thermoplastic P1 rubber, and also to improve the compression set, thereby completing the present invention.

That is, the gist of the present invention resides in an improved fluorine-containing thermoplastic rubber composition comprising a fluorine-containing thermoplastic rubber blended with silicic acid and/or a salt thereof.

In the present invention, fluorine-containing thermoplastic rubber refers to a relatively low
B refers to rubber that has vulcanized rubber elasticity at (for example, around room temperature) and exhibits plasticity when heated.

The fluorinated thermoplastic rubber preferably consists of at least one elastomeric polymer chain segment and at least one non-elastomeric polymer chain segment, at least one of which is a fluorinated boria chain segment. Particularly preferred is one in which the weight ratio of elastomeric polymer chain segments to non-elastomeric polymer chain segments is 40-95:5-60.

A particularly preferable example of a fluorinated thermoplastic rubber is one consisting of a chain consisting of 2 or 13 polymer chain segments, an iodine atom present at one end of the chain, and an iodide compound present at the other end of the chain. at least 1
one of the polymer chain segments (if the chain consists of two polymer chain segments) or one or two (if the chain consists of three polymer chain segments) ) is (1) vinylidene fluoride/hexafluoropropylene or pentafluoropropylene/tetrafluoroethylene (molar ratio 45-90.5-500-35)
Zuma + 2 + perfluoro(01-C3 alkyl vinyl ether)/tetrafluoroethylene/vinylidene fluoride (molar ratio 15-75; 0-85; 0-8
5) Selected from polymers, molecular weight 3Q 000-1
.
0:0-100) polymer and (4) ethylene/tetrafluoroethylene/hexafluoropropylene, 3,3
．． 3-Trifluoropropylene-1,2-1-lifluoromethyl-3,3,34-lifluoropropylene-1
or perfluoro(C-03 alkyl hinyl ether) (mol Lt 40-60:60-40:O-30) polymers with a molecular weight of 3,000-400,00
0 non-elastomeric polymer chain segments, and the weight ratio of elastomeric polymer chain segments to non-elastomeric polymer chain segments is from 40 to 95.5 to 6.
1, which is 0, includes fluorine-containing thermoplastic rubber.

A preferable fluorine-containing thermoplastic rubber used in the present invention is described in JP-A-53-3495.

A typical structure of fluorine-containing thermoplastic rubber is, for example, the following formula.

Q [(A-B-......)I].

[In the formula, Q is a residue obtained by removing the iodine atom from the iodide compound, and A, R, ... are each a polymer 9-portion segment (X, at least one of which is (1) is a fluorine-containing polymer sheath segment), (2) is an iodine atom separated by one atom from the iodide compound, and n is Q.
represents the number of bonds in . ], basically consisting of a chain consisting of at least two types of polymer chain segments, an iodine atom bonded to both ends of the chain, and a residue obtained by removing at least one iodine atom from an iodide compound. It consists of minutes. Therefore, Mll fc'at least 2
The polymer chain segments of the species are different from the adjacent polymer chain segments (for example, the structure and composition of the monomer units that constitute them are different).

), and at least one of the soft straws is a fluorine-containing polymer chain segment, and consists of at least one hard segment and at least 1T soft segment. Preferably, each polymer chain segment is a molecule! At least one of the polymer chain segments has a molecular weight of 30,000 or more, excluding so-called telomer regions. In addition, if the iodide compound has a polymerizable double bond, the residue obtained by removing at least an iodine atom from the iodide compound is a monomer constituting the polymer segment or some substitution derived from the iodide compound. What can you do with your minutes? These fluorine-containing thermoplastic rubbers usually contain 0.001 to 10% by weight of iodine atoms.

Commercially available silicic acid and its salts can be used. Examples of salts include magnesium salts, potassium salts, aluminum salts, iron salts, zirconium salts, and specific examples include talc and clay. Of these, silicic acid is most preferred.

Silicic acid and/or its salts are added to an aqueous dispersion of fluorine-containing thermoplastic rubber, and if necessary, coagulated by coagulation (e.g., a water-soluble electrolyte, specifically an inorganic acid such as hydrochloric acid, sulfuric acid, acetic acid, etc.). Co-coagulation method by adding organic acids such as oxalic acid, inorganic salts such as magnesium chloride, sodium chloride, ammonium chloride, and aluminum sulfate, inorganic bases such as slaked lime and quicklime, various organic amines, etc.
If the fluorine-containing thermoplastic rubber is soluble in the solvent, the method is to dissolve it, add free silicic acid, etc. to it, and remove the solvent.
Furthermore, it can be blended into a fluorine-containing thermoplastic rubber by kneading it using a mixing roll, a Nycoo mixer, a Banbury mixer, etc. in the same way as ordinary rubber.

The amount of silicic acid and/or its salt is 2 to 50 parts by weight, preferably 5 to 3 parts by weight, per 100 parts by weight of the fluorine-containing thermoplastic rubber.
0 heavy risk combination is good.

The preferable fluorine-containing thermoplastic rubber used in the present invention essentially cures by simply cooling after molding without adding ERjiFII like ordinary fluororubbers, so it is not necessary to add a vulcanizing agent. There is no need to add other additives, but depending on the purpose, organic peroxide compounds, polyhydroquino compounds, vulcanization accelerators,
A polyamine compound, which is well known as 7J sulfur II of fluororubber, is added. These vulcanized 61j
When adding to a fluorine-containing heat-collecting +l+l outer rubber, known vulcanization methods such as peroxide vulcanization, polyol vulcanization, and polyamine vulcanization can be employed. In addition, the method of curing by light or heat by adding a light- or heat-functional rtS compound may also be used.

1- When an organic peroxide compound is used for carving ~
It is usually desirable to use a polyfunctional compound in combination, and generally the functional group is CI (2=CI-).

Examples include one or more of CH=CH-CH2-, CF2=cp-, and the like.

Next, examples and comparative examples will be shown to specifically explain the present invention.

Examples 1-2 Vinylidene fluoride/hexafluoropropylene/
Tetrafluoroethylene (molar ratio 50:30:20
) 85% by weight of polymer segment and ethylene/tetrafluoroethylene/hexafluoropropylene C molar ratio 43:49:8) 15% by weight of polymer segment with fluorine-containing! A weight ratio of S plastic rubber (this is referred to as Rubber 8) and a fluorine-containing thermoplastic rubber (this is referred to as Rubber B) in which the latter segment is a polyvinylidene fluoride segment in Rubber 8 is 50:50.
Silicic acid (Aerosil-200:
P-24 O-ring sample piece (for Q+1 ring) made from a composition containing 5 parts by weight (Japan Aerosil Co., Ltd.)
-E compression molding machine was used to melt the material at 230°C, pressurize it for 10 minutes, and immediately cool it with water on the upper and lower sides to harden it) at 100°C for 24 hours and compress it by 25%, resulting in compression permanent strain. was 56%.

Further, when a similar test was conducted on a composition containing 10 parts of talc instead of silicic acid, the compression permanent warp was almost the same as above.

Comparative Examples 1 to 2 Fluorine-containing thermoplastic rubbers A and B (see Example 1) were individually molded into sample beads similar to those in Example 1, and the resulting sample pieces were compressed in the same manner as in Example 1. When the permanent strain was measured, the former was destroyed, and the latter had a compression permanent strain of 95f.

Met.

From these results, it can be seen that the fluorine-containing thermoplastic rubber is 10
Under 25% shrinkage at 0°C, it will destroy or 9
It can be seen that a compression set of as much as 5% remains, and by adding silicic acid and/or its salt, there is no destruction and the compression set is significantly improved.

Patent applicant: Daikin Industries, Ltd.

Claims (4)

[Claims] (1) An improved highly fluorine-containing thermoplastic rubber composition comprising silicic acid and/or its salt blended with a fluorine-containing thermoplastic rubber. (2) The fluorine-containing thermoplastic rubber is composed of at least one elastomeric polymer chain segment and at least one non-elastomeric polymer sheath segment, at least one of which is a fluorine-containing polymer chain segment. The composition according to claim 1, which is an elementary thermoplastic rubber. (3) The composition according to claim 2, wherein the fluorine-containing thermoplastic rubber comprises 40 to 95 parts by weight of elastomeric polymer chain segments and 5 to 60 parts by weight of non-elastomeric polymer chain segments. (4) The composition according to claim 1, wherein the fluorine-containing thermoplastic rubber is blended with LIT.