JPS5941350A - Improved fluorine-containing thermoplastic rubber composition - Google Patents

Abstract

PURPOSE:To prepare the titled composition having improved chemical resistance as wel as improved mold releasability and sizability, by compounding a low- molecular weight polytetrafluoroethylene to a fluorine-containing thermoplastic rubber. CONSTITUTION:A fluorine-containing thermoplastic rubber is compounded with a low-molecular weight polytetrafluoroethylene (having a number-average molecular weight of 500-20,000). 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 segment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved fluorine-containing thermoplastic rubber composition, and more specifically, to a composition containing low molecular weight polytetrafluoroethylene (hereinafter referred to as PTFE). This invention relates to a thermoplastic rubber composition having improved mold releasability, sizing properties, etc.

Fluorine-containing thermoplastic L! i,! 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 (for example,
- It is used for various purposes by being molded into rings, seals, etc., or covered with electric wires, exterior materials, fasteners, etc.

However, fluorine-containing thermoplastic rubbers stick to molds and rolls during molding and rolling, and their release properties are not satisfactory. Furthermore, the sizing properties are not sufficient.

The present inventors conducted research to improve these drawbacks of fluorine-containing thermoplastic rubber without impairing its other excellent properties. & By doing so, the release plate of the fluorine-containing thermoplastic comb,
The present inventors have discovered that it is possible to improve the sizing property and also to improve the chemical resistance, thereby completing the present invention.

That is, the gist of the present invention relates to an improved fluorine-containing thermoplastic rubber composition comprising a fluorine-containing thermoplastic comb blended with a low molecular weight -iii 1'l' Ii E.

In the present invention, the fluorine thermoplastic comb refers to a comb that has IJ11 comb elasticity at a relatively low temperature (for example, near crystalline) and exhibits plasticity when heated.

The fluorinated thermoplastic comb 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 polymer chain segment. In particular, it is preferable that the weight ratio of the elastomeric polymer chain segment to the non-elastomeric polymer ε1-segment is 40-95:5-60.

A particularly preferred example of the fluorine-containing thermoplastic rubber is a chain consisting of two or three types of polymer chain segments, and an iodine atom present at one end of the chain, and an iodide compound present at the 1m end of the chain. at least 1 from
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 matahhentafluoropropylene/tetrafluoroethylene (molar ratio 45-90.5-50:0-35) polymer and! J'12+ perfluoro(C1-C3 alkyl vinyl ether)/tetrafluoroethylene/vinylidene fluoride (molar ratio 15-75:0-85:O
~85) selected from polymers with a molecular weight of 30,000
~1,200,000 elastomeric polymer chain segments, the remainder of the polymer chain segments being (3) vinylidene fluoride/tetrafluoroethylene (molar ratio O~10
0:O~100) polymer and (4) ethylene/tetrafluoroethylene/hexafluoropropylene, 3
,3.3-)! J fluoropropylene-1,2-trifluoromethyl-3,3,3-1-lifluoropropylene-1 or perfluoro(01-C; γ-alkyl hinyl ether) (mol Jt, 40-60:60- 40°0
~30) Molecules 1rt3,0 selected from polymers
00 to 400,000 non-elastomeric polymer chain segments, and the weight ratio of elastomeric polymer chain segments to non-elastomeric polymer chain segments is 40 to 95゛5 to 6
0, fluorine-containing thermoplastic ('1.com).

A preferable fluorine-containing thermoplastic comb used in the present invention is described in JP-A-5:3-3495.

The typical structure of a fluorine-containing thermoplastic comb is as follows.

Q((/＼-13-・・・・・・・・・)　I　).

[In the formula, Q is a residue obtained by removing an iodine atom from an iodide compound, and A, B, ... are each a polymer chain segment (V, at least one of which is a fluorine-containing polymer chain segment) ), ■ represents the iodine atom released from the iodide compound, and 11 represents the number of bonds in Q. ], basically at least 2
A chain consisting of polymer chain segments of species and its ends 4
The iodine atom bonded to the iodide compound consists of a residue obtained by removing at least one iodine atom from the iodide compound as an essential component. Therefore, at least two polymer chain segments in Section 1j are of a different type from the adjacent polymer y-1 segment (for example, the structure or composition of each of the constituent units is different). ), at least one of which is a fluoropolymer chain segment, consisting of at least one hard segment and at least one soft segment. Preferably, each polymer chain segment each has a molecular weight of 3,000
0 to -L, but at least one polymer chain segment has molecules 1t3o, oooU), excluding the so-called telomer region.

In addition, if at least the iodine atom is removed from the iotide compound and the iotide compound has a 211'' bond outside the medium plan, the polymer 'jir segment is contaminated by 1. These fluorine-containing thermoplastic rubbers usually contain iodine atoms in an amount of 0.001% to 1%.

The P1N-P-E low-molecular-m compound used in the present invention has a P14 equivalent molecular weight of -111 or about 500 to 200,000.
TFE, generally I) 'rI=' A method of decomposing the filtrate by heating the high polymer at 450-600°C for a long time, in the presence of a molecule-ITI filA1 moderating agent. It can be produced by a method of obtaining a tetrafluoroethylene telomer using tetrafluoroethylene as a base, a method of irradiating a tetrafluoroethylene high polymer with fugitive radiation, and then mechanically crushing it. Commercially available products can also be used.

Low molecular weight 1) T is blended in an amount of 5 to 120 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of the fluorine-containing thermoplastic rubber.
If I='E is blended in a large amount, the transparency of the fluorine-containing thermoplastic rubber will be impaired, which is not preferable.

The formulation is an aqueous dispersion of fluorine-containing thermoplastic tll=-com with a low molecular weight of 1' T I'' l! : Add,
If necessary, coagulants (e.g. water-soluble electrolytes, specifically salts, sulfuric acid, etc., organic compounds such as acetic acid, oxalic acid, magnesium chloride, sodium chloride, ammonium chloride, aluminum sulfate, etc.) A method of co-coagulating by adding inorganic salts, slaked lime, quicklime etc. (organic bases, various organic amines, etc.), or if the fluorine-containing thermoplastic comb is soluble in a solvent, it is made into a solution, low molecular weight P1'1
This can be carried out by adding 1' and removing the solvent, or by kneading using a mixing roll, kneader, Banbury mixer, etc. in the same way as ordinary rubber.

Next, the present invention will be specifically explained by showing Examples and Comparative Examples.

Example 1 and Comparative Example 1 Vinylidene fluoride/hexafluoropropylene 2
'Tetrafluoroethylene (molar ratio 50:30:2
0) Polymer segment 85% and ethylene/
'Tetrafluoroethylene/hexafluoropropylene/
(Mole ratio 43:49:8) Fluorine-containing thermoplastic 9'/j 100 width 1. For some H, low molecular weight bL 11'
l'l・E (Lefron 1.-5, Kuikin Kogyo Co., Ltd. kl:fJ) 5 [I item r: part or 251i-composition blended comb composition was preheated to 240°C (after IHI heating, P-240-!j 7 ri; 30-cavity mold (
(no plating), washed 4 times at 240℃, 1s J 35
K9/l・! Hold for 10 minutes at GJ-1 and then press in a coolable press at 35 Kq/t non-GJ-
and held for 10 minutes. After cooling was completed, the mold was opened to one side and opened easily. The molded products could be easily and continuously removed from the mold. The time required for one shot was approximately 30 minutes in the case of the low deposit amount P-1-1;'E 5-layer combination, and approximately 25 minutes in the case of the 25-layer combination.

For comparison, when the same composition without low molecular weight PTFE was molded in the same way, the mold did not open well after cooling, and the O-rings had to be removed one by one from the mold. I had to. Therefore, the required time for l shots is 1? JJ was there for 40-60 minutes.

Example 2 and Comparative Example 2 Low molecular weight iji was added to the fluorine-containing thermoplastic rubber used in Example 1.
l) 'I-1・El 51ij 1'l (%) The rubber composition was injection molded at 50°C, and when looking at the moldability of 141F for each shot, the molded product was transparent and separated. While molding was easy, the one that did not contain low-molecular IT P E did not form Mitt shape unless it was removed with strong force.
Some parts were found to be damaged. , Patent applicant Daigin Kogyo Co., Ltd.

Claims (1)

[Claims] (1) Fluorine, j+71 'iiJ plastic rubber with low content'
An improved fluorine-containing thermoplastic comb composition comprising f-Ift polytetrafluoroethylene. (2) a fluorine-containing thermoplastic rubber, at least one elastomeric polymer chain segment and at least one non-elastomeric polymer chain segment;
The composition according to claim 1, wherein at least one of the fluorine-containing plastic rubbers is a fluorine-containing polymer chain segment. 3) The composition of claim 2, wherein the fluorine-containing thermoplastic comb comprises 40 to 95 parts of elastomeric polymer chain segments and 111 parts of 5 to 60 parts of non-elastomeric polymer chain segments. (4) Number of low molecular weight polytetrafluoroethylenes 5
The composition according to claim 1, having a molecular weight of 500 to 20,000.