JPH0627234B2 - Extruded product - Google Patents

Description

TECHNICAL FIELD The present invention relates to an extruded product having excellent heat resistance and oil resistance.

(Prior art and problems) Since tetrafluoroethylene-propylene-based copolymers have excellent heat resistance and oil resistance, they are used for extruded products such as tubes and packing that require heat resistance and oil resistance. Is being started. Conventionally, an extrusion-molded article made of a composition containing a tetrafluoroethylene-propylene-based copolymer as a main component contains an allyl compound as a cross-linking aid and an organic peroxide as a cross-linking agent in the composition. After extruding the product, press-heat crosslinking with pressurized steam so that voids do not occur in the product, or use a vent type extruder to suck in a small amount of water and gas contained in the composition under vacuum. ,
A method is employed in which extrusion molding is carried out and heat crosslinking is carried out under normal pressure.

However, in the case of pressure heating crosslinking, since there is no core wire that can withstand tension like electric wires, continuous extrusion molding-crosslinking-takeover cannot be performed in one step, and after short cutting, crosslinking must be done in batch mode. In addition to increasing the number of processes, the production capacity will decrease, and a boiler that generates pressurized steam will be required.
On the other hand, when using a vent-type extruder capable of heat-crosslinking under normal pressure, it takes a considerable time for setup unlike an extruder normally used, and care must always be taken so that the vacuum degree of the vacuum pump does not drop. Moreover, since the vent type extruder is a large device with a special structure that requires multiple cylinders or large cylinders equivalent to it and a vacuum pump, not only is it expensive, but it also requires a large installation space, In addition, a large amount of compound remains in the cylinder, resulting in a higher process cost than an extruder that is normally used, which is economically disadvantageous.

(Object of the Invention) An object of the present invention is to solve the above problems and to provide an extrusion-molded article having excellent heat resistance and oil resistance. Further, an object of the present invention is to inexpensively produce such an extrusion-molded product by a method of continuously heating and crosslinking at normal pressure in the same step after extrusion molding without using a vent type extruder.

(Structure and Action of the Invention) That is, the extrusion-molded product of the present invention comprises a composition containing a tetrafluoroethylene-propylene-based copolymer as a main component, a methacrylic acid ester or an acrylic acid ester as a crosslinking aid, and a crosslinking agent. The mixture obtained by adding the organic peroxide is an extruded product obtained by heating at atmospheric pressure for crosslinking, or a composition containing a tetrafluoroethylene-propylene copolymer as a main component, and methacrylic acid as a crosslinking aid. An ester or an acrylic ester,
An organic peroxide, which is a cross-linking agent, is mixed, and silicone rubber is mixed therein with a tetrafluoroethylene-propylene copolymer 10.
It is an extrusion-molded product obtained by heating a mixture obtained by adding 200 parts by weight or less to 0 parts by weight and heating the mixture under normal pressure to crosslink.

The tetrafluoroethylene-propylene copolymer is usually crosslinked by using an allyl compound as a cross-linking aid and an organic peroxide together as a cross-linking agent, but in the present invention, a methacrylic acid ester or a cross-linking aid is used. The feature is that the acrylic ester is used in combination with an organic peroxide as a crosslinking agent for crosslinking.

The mixture according to the present invention can be crosslinked even at a low temperature of 80 to 100 ° C., and voids do not occur in the product even if it is heated and crosslinked at normal pressure without using a vent type extruder. When a crosslinking aid such as an allyl compound, oxime compound, sulfur, maleimide compound, etc. is used as the crosslinking aid instead of the methacrylic acid ester or acrylic acid ester, or the methacrylic acid ester or acrylic acid ester is not used in combination with the organic peroxide. 80 to 10 when used alone in the above, or when used alone as a crosslinking agent.
At a low temperature of 0 ° C., almost no crosslinking occurs in a unit of several tens of minutes, and even if the temperature is raised to 150 to 200 ° C., voids are generated in the product at normal pressure. Examples of the methacrylic acid ester or acrylic acid ester in the present invention include trimethylolpropane trimethacrylate, ethylene dimethacrylate, polyethylene glycol dimethacrylate, cyclohexyl methacrylate, dialkylaminoalkyl methacrylate, aluminum methacrylate, aluminum acrylate, zinc methacrylate, zinc acrylate and the like. . These may be used alone or in combination of two or more. As the organic peroxide, various peroxide compounds which are generally used can be used. In addition to the above, generally used rubber compounding chemicals such as a filler, a reinforcing agent, a stabilizer, a softening agent, and a pigment may be added if necessary.

Further, a mixture containing, as a main component, the tetrafluoroethylene-propylene copolymer of the present invention, a methacrylic acid ester or an acrylic acid ester which is a crosslinking agent, and an organic peroxide which is a crosslinking agent is added at 80 to 100 ° C. The silicone rubber that can be crosslinked at a low temperature and that does not generate voids in the product even if it is heated and crosslinked at normal pressure without using a vent type extruder is mixed at any ratio It is possible to carry out crosslinking at a low temperature of 80 to 100 ° C. without loss of temperature, and there is an advantage that voids do not occur in the product even if it is heated and crosslinked at normal pressure without using a vent type extruder. However, silicone rubber is a type of oil,
Insufficient resistance to solvents, and when the mixing ratio with respect to 100 parts by weight of tetrafluoroethylene-propylene copolymer exceeds 200 parts by weight, oil resistance and solvent resistance are greatly reduced, and heat and oil resistance are characteristic. Is not practical as an extrusion molded product.

Silicone rubber is usually filled with a filler such as silicone rubber 100
It is commercially available as a silicone rubber compound containing about 30 to 100 parts by weight with respect to parts by weight, and the mixture of the present invention may be a mixture obtained by using the silicone rubber compound.

The production method of the present invention is exactly the same as the atmospheric pressure heating crosslinking method, which is inexpensive in terms of the process cost of the silicone rubber extruded product, and the mixture of the present invention is extruded and then heated at about 200 ° C. in a heating furnace.
Crosslinking is carried out by heating under atmospheric pressure for about a minute. The temperature of the cylinder and head of the extruder is set to 50 ° C or lower in consideration of the fact that the insulator mixture is crosslinked at 80 ° C.

(Examples and Comparative Examples) The mixture shown in Table 1 was extruded into a tube shape having a thickness of 0.8 mm and an inner diameter of 2 mm, and then heated in a heating furnace at 200 ° C for 5 minutes at normal pressure to crosslink. At this time, the cylinder and head of the extruder were set at 50 ° C. Incidentally, in the composition of Table-1,
A siliceous filler was used as the filler, and silicone oil was used as the softening agent. Sodium stearate was used as a lubricant. In the mixed system of the tetrafluoroethylene-propylene copolymers of Examples 3 and 4 and Comparative Example 4 and the silicone rubber, the crosslinking agent of the silicone rubber was added in proportion to the mixing ratio.

Table 2 shows the test results of Examples 1 to 4 and Comparative Examples 1 to 4.

(Effects of the Invention) As shown in these test results, in Examples 1 to 4, voids do not occur in the test product even when the crosslinking under atmospheric pressure is carried out at low process cost. On the other hand, when other cross-linking aids were used instead of the methacrylic acid ester or the acrylic acid ester as in Comparative Examples 1 to 3, in the atmospheric pressure heating cross-linking, innumerable voids were generated in the test product to give a product. I can not use it. Further, as in Examples 3 and 4, mixing with a silicone rubber that can be crosslinked by heating under normal pressure does not cause a significant decrease in oil resistance up to 200 parts by weight with respect to 100 parts by weight of the tetrafluoroethylene-propylene copolymer, and is practically used. No problem. On the other hand, Comparative Example 4
When the amount of silicone rubber is too large as described above, the oil resistance, which is a characteristic of the tetrafluoroethylene-propylene copolymer, is lost.

As described above, the present invention has excellent heat resistance and oil resistance, and
It is an extruded product that can be manufactured at low cost.
By mixing a silicone rubber, which is cheaper than a fluorinated ethylene-propylene-based copolymer, a cheaper and more economical extruded product can be obtained.

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Claims (2)

[Claims] 1. A mixture obtained by adding a methacrylic acid ester or acrylic acid ester, which is a crosslinking aid, and an organic peroxide, which is a crosslinking agent, to a composition containing a tetrafluoroethylene-propylene-based copolymer as a main component. An extruded product consisting of a heat-crosslinked product. 2. A composition containing a tetrafluoroethylene-propylene-based copolymer as a main component, and a mixture of a methacrylic acid ester or an acrylic acid ester which is a cross-linking aid and an organic peroxide which is a cross-linking agent. An extruded article obtained by heat-crosslinking, which comprises a mixture of 200 parts by weight or less of silicone rubber added to 100 parts by weight of a tetrafluoroethylene-propylene copolymer.