JPH0341139A - Polymer blend composition - Google Patents

Abstract

PURPOSE:To obtain a polymer blend composition improved in heat resistance, flexibility and flame retardancy by blending a specified polymer blend with a two-component liquid silicone rubber and independently crosslinking the polymers to form an interpenetrated polymeric network structure. CONSTITUTION:A polymer blend (A) is obtained by blending 20-60wt.% chlorinated PE (a) with 80-40wt.% ethylene/vinyl acetate copolymer (b) of a vinyl acetate content of 10-45wt.%. 100 pts.wt. component A is blended with 10-100 pts.wt. two-component liquid silicone rubber (B) which is of a type of a mixture (about 1:1) of a component having a skeleton of dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane or the like and a hydroxyl group on its end or in the side chain with a component having a vinyl group wherein the viscosities of these components are substantially the same and can be subjected to an addition vulcanization reaction in the presence of a platinum compound. The resulting blend is crosslinked so that an interpenetrated polymeric network structure wherein component (a) and (b) are cocrosslinked and components A and B are independently crosslinked may be formed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a polymer blend composition that has heat resistance, excellent flexibility, and flame retardancy, and is useful as an electric wire insulating material. It is about things.

[Prior art] Chlorinated polyethylene is produced by partially replacing hydrogen atoms in polyethylene with chlorine atoms, and is generally produced by suspension chlorination of polyethylene using a medium-low pressure method. It is true.

Depending on the structure and molecular weight of the raw polyethylene, the chlorine content, the distribution of combined chlorine, the presence or absence of residual crystallinity, it is possible to obtain products with a wide range of physical properties ranging from hard plastic to rubber. In addition, since it is a halogen-based polymer that does not have double bonds in the main chain, it has weather resistance, ozone resistance, flame retardancy, 1 (impact strength,
It has many excellent properties such as chemical resistance and oil resistance.

For this reason, chlorinated polyethylene is attracting attention as a material for electric wires and cables, and due to its electrical properties, it is often used as a sheath material as an alternative to polychlorograne rubber and chlorosulfonated polyethylene, but depending on its composition, It is also effectively used as an insulating material.

Furthermore, when viewed as a flame-retardant material, it exhibits excellent flame-retardant properties because it contains halogen, and is promising as a material that can withstand the various flame-retardant tests required for recent T-wire and cable materials. being watched.

On the other hand, ethylene-vinyl acetate copolymers, like other ethylene-based copolymers, are produced by high-pressure radical polymerization, and 2'Ia type autoclaves and tubular reactors are known as equipment for this purpose. . A method for producing an ethylene copolymer using such a high-pressure polymerization method was first announced by ICT in 1938.

The original purpose of copolymerizing ethylene with other vinyl monomers is to overcome the disadvantages of polyethylene, which is originally non-polar, by introducing polar materials that improve printability, adhesion, transparency, flexibility, etc. The purpose is to impart physical properties, and the same can be said for ethylene vinyl acetate.

However, like PVC and rubber, ethylene vinyl acetate copolymer does not have a clear yield point, which is a characteristic of polymers with high entropic elasticity, and this tendency increases as the amount of copolymerized comonomer increases. It becomes highly flexible and has excellent toughness.

Therefore, in terms of low-temperature properties, it shows a glass transition temperature of -30 to -50°C, good low-temperature flexibility, and a low brittle temperature.In addition, as for the electrical properties, as the vinyl acetate content increases, Although there is a tendency for the flame retardancy to decrease, it can be said that it is generally superior.However, from the viewpoint of flame retardancy, it has the disadvantage that it is considerably inferior to the above-mentioned chlorinated polyethylene.

Therefore, by blending the two and co-crosslinking them by taking advantage of their excellent properties, it is possible to obtain a material that exhibits good properties both as an insulating material and as a sheath material. It is possible to obtain a material that has excellent flexibility, flame retardancy, oil resistance, heat resistance, and good electrical properties.

[Problem to be solved by the invention] The above-mentioned chlorinated polyethylene and ethylene-vinyl acetate copolymer blend copolymer g (although there is no specified i!L continuous use temperature as defined in the general standard) , 105
It has heat resistance up to about 0.9°C, and electric wires using this material as a covering material are widely used as sunrise wires for motors and for vehicles.

However, due to the recent trend toward smaller and more precise equipment, there has been a noticeable rise in temperature due to overcrowded wiring, and in the allowable temperature of the atmosphere in which A8 class equipment is used.
Heat resistance even higher than the above-mentioned temperature range has come to be required4.In order to meet this demand for higher heat resistance, the addition of antioxidants or the use of heat-resistant polymers (e.g. silicone rubber) have been developed. Blends or copolymerization with other materials are being considered.

However, countermeasures using antioxidants have their own limits, and
If it is added in a large amount, crosslinking may be inhibited or a so-called bloom phenomenon in which precipitation occurs on the surface during use may occur, which is not preferable.

Further, although the method of blending silicone rubber or the like is effective in improving heat resistance if it is simply blended, there is a problem in that the mechanical properties are greatly reduced, and the expected properties are not necessarily obtained.

The object of the present invention is to solve the problems of the prior art as described above, and to provide novel chlorinated polyethylene and ethylene vinyl acetate that can effectively improve heat resistance without adversely affecting other properties such as mechanical properties. It is an object of the present invention to provide a polymer blend composition comprising a copolymer.

[Means for Solving the Problems] The present invention provides that a platinum compound is added to 100 parts by weight of a polymer blend consisting of 20 to 60% by weight of chlorinated polytamagolene and 80 to 40% by weight of ethylene vinyl acetate copolymer. A two-component liquid silicone rubber capable of addition vulcanization reaction in the presence of is blended in a total amount of 10 to 100 parts by weight, and the chlorinated polyethylene and ethylene vinyl acetate copolymer are co-crosslinked. Silicone rubber is made up of polymer network channels that are crosslinked with each other and interpenetrate with each other.

There are various grades of chlorinated polyethylene depending on the chlorine content, presence or absence of crystals, molecular weight, molecular weight distribution, etc., but the grade is not particularly important in the present invention.

Similar to chlorinated polyethylene, ethylene-vinyl acetate copolymers come in various grades depending on their molecular weight, molecular weight distribution, vinyl acetate content, arrangement on the molecular chain, etc. Although there are no specific regulations, the vinyl acetate content is 10-45
A range of % is desirable.

As for the ratio of blending these, it is necessary to blend chlorinated polyethylene in a range of 20 to 60% by weight; if it is less than 20% by weight, the flame retardance will be poor, and if it is more than 60% by weight, sufficient flexibility will not be obtained. I won't be able to do it. Therefore, the corresponding blending range of the ethylene vinyl acetate copolymer is in the range of 80 to 40% by weight. Both of these polymers are co-crosslinked by a silane grafting process which can be activated by water in the presence of a catalyst to produce a crosslinking reaction.

Types of silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltonoacetoxysilane,
Examples include γ-methacryloxypropyltrimethoxysilane. These can be grafted with peroxides such as dicumyl peroxide.

2rf9. Spun liquid silicone rubber has a skeleton such as dimethylsiloxane, methylphenyldioxane, or diphenylsiloxane, and is a type that crosslinks through an addition reaction between a component having a hydrogen group at the end or side chain and a component having a vinyl group. be. These two components generally have approximately the same viscosity and are often mixed at a ratio of 1:1.The viscosity, or molecular weight, can be varied depending on the purpose.The amount of this two-component liquid silicone rubber mixed is limited to a range of 10 to 100 parts by weight per 100 parts by weight of the above polymer blend because if it is less than 10 parts by weight, the desired heat resistance cannot be imparted, and if it exceeds 100 parts by weight, tearing may occur. This is because the strength decreases.

Stabilizers, antioxidants, lubricants, flame retardants, fillers, reinforcing agents, colorants, etc. can be added to the polymer blend.

[Function] If a two-component liquid silicone rubber is blended in the above range with a blend of chlorinated polystyrene and ethylene-vinyl acetate copolymer and a crosslinking reaction occurs independently, an interpenetrating polymer network structure is formed. As a result, the tear strength and tensile properties are improved, and the heat resistance is improved.

[Example] The present invention will be described below with reference to Examples.

The test materials having the compositions shown in the Examples and Comparative Examples in Table 1 were kneaded for about 10 minutes using a B-type Pan Bali mixer, and then formed into a sheet with a thickness of about 1+m using a 6" roll.
The material was pressed for 10 minutes using a press maintained at .degree. C. and molded into a 1-inch thick sheet (V5 (addition reaction of liquid silicone)).

Furthermore, after coating the sheet surface with a tinge of catalyst (e.g. dibutyltin dilaurate), it was wrapped loosely in aluminum foil, kept in a suitable container with water at the bottom without being directly immersed in water, and heated at 80°C. The mixture was left to stand for 24 hours to carry out a co-crosslinking reaction between the chlorinated polyethylene and ethylene/vinyl acid.

The evaluation methods for each are as follows.

Thermal property: Using a JIS type aging tester maintained at 180° C., a graph was created that plotted elongation and time at several points over time, and from this graph, the time required for elongation to reach 50% was determined for each.

Measured according to JISK7201 Established.

After leaving it for one day in a constant temperature room at 20℃, Punch shopper with dumbbell size 3 Using a type-biki bow length test@machine Measurements were made at a rate of 500 h/ll1n.

100% of the above tensile properties The modulus was measured. This value sex: deflection Endurance Possible Oxygen index: (Flame retardance) Tensile properties: 0.5kf/m penalty 2 or less This was used as a measure of flexibility.

1 Crack strength: Measured at a speed of 500 cm/11 stitches using the same Schopper type tensile testing machine as above using a B type sample in accordance with JIS K6301.The evaluation results are shown in the lower column of Table 1. show.

Regarding heat resistance, as shown in Comparative Example 1, the conventional blend of chlorinated polyethylene and ethylene/vinyl acid copolymer has a lifespan of around 60 hours, whereas the life of the N
All of the samples O31-4 have an interpenetrating polymer network structure, so they exhibit excellent heat resistance and at the same time are superior to Comparative Example 1.
It maintains tensile properties almost equivalent to those of the non-blended silicone rubber system shown in . On the other hand, when looking at comparative examples, it can be seen that chlorinated polyethylene or No. 2, which is within the range specified by the present invention, has poor visibility. Also, unblended N01 of chlorinated polyethylene
In No. 3, the oxygen index, which is a measure of flame retardancy, is low, and self-extinguishing properties are lost. Furthermore, in No. 4, the amount of liquid silicone rubber added exceeds the range of the present invention, and as a result, the tear strength is significantly reduced.

[Effect of the Invention 1] As described above, the polymer blend composition of the present invention maintains flexibility without deteriorating mechanical properties such as tensile strength and tear strength, and also maintains heat resistance. It is possible to improve the temperature to a large extent by +lJ, further increasing its usefulness in industry as a coating material for electric wires and cables used in fields prone to high temperatures.

Claims (1)

[Claims] (1) Two-component system capable of addition vulcanization reaction in the presence of a platinum compound with respect to 100 parts by weight of a polymer blend consisting of 20-60% by weight of chlorinated polyethylene and 80-40% by weight of ethylene-vinyl acetate copolymer. The liquid silicone rubber is blended in a total amount of 10 to 100 parts by weight, and the chlorinated polyethylene and ethylene vinyl acetate copolymer are co-crosslinked. A polymer blend composition formed by forming a polymer network structure that penetrates into the polymer network.