JPH0613632B2 - Flame-retardant resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a flame-retardant resin composition, in particular, a foamed carbonized layer which is dense and does not crack when exposed to a flame, and the inner layer material can be safely protected by its heat insulating action. The present invention relates to a vinyl chloride resin composition that protects, has oil resistance and heat distortion resistance.

Conventionally, when making a soft vinyl chloride resin flame-retardant, the oxygen index of the resin composition is increased by adding a flame-retardant agent made of a compound such as halogen, phosphorus, antimony, boron, or aluminum, and the purpose of flame-retardant Was often reached. In recent years, a higher degree of flame retardancy has been required for resin compositions used for electric wires, cable jackets, and other protective jackets for inflammable inner layer materials. As described above, it is not enough to increase the oxygen index of the resin composition, and at the time of flame contact, the coating material forms a dense foamed carbonized layer, which acts as an adiabatic action on the inner layer material and melts or is appropriately heated by heat. It has come to be a condition that flame retardancy must be fulfilled in order to prevent the above.

Various attempts have already been made to provide a resin composition suitable for a coating material having such conditions. For example, in Japanese Patent Publication No. 52-41786 and Japanese Patent Publication No. 53-18065, it is preferable that a ternary graft polymer obtained by graft-polymerizing vinyl chloride on an ethylene-vinyl acetate copolymer is foamed and expanded at the time of flame contact to perform adiabatic action. It is introduced to be a composition. Since this composition has already been plasticized without the use of an external plasticizer, it does not cause problems such as migration of the plasticizer, but has little oil resistance and heat distortion resistance. It cannot be used in the required fields. On the other hand, ethylene-vinyl acetate copolymer resin, acrylonitrile-butadiene rubber, chloroprene rubber, chlorinated polyethylene, acrylic acid ester polymer and the like which are compatible with the mixture constituting the present invention, that is, vinyl chloride resin, A resin composition prepared by adding an external plasticizer and a flame retardant to a compound of a polymer compound exhibits excellent oil resistance and heat distortion resistance, but it expands and expands during flame contact to form a dense foamed carbonized layer. It is difficult to exhibit desirable properties like the above-mentioned ternary graft copolymer.

The applicant of the present application discloses, as previously disclosed in Japanese Patent Laid-Open No. 55-157640, a mixture of a vinyl chloride resin and a polymer compound compatible therewith, molybdenum selected from metal salts of molybdic acid. Proposal of a resin composition formed by adding a compound and melamine phosphate and melamine borate, which not only has excellent oil resistance and heat distortion resistance but also forms a stable foamed carbonized layer that is dense and does not crack when flame contacted did. The molybdenum compound has a function of foaming and expanding the resin during flame contact, and melamine phosphate and melamine borate stabilize the foamed carbonized layer.

In this resin composition, melamine phosphate and melamine borate are 2 to 40 parts by weight based on 100 parts by weight of the vinyl chloride resin,
Generally, it is necessary to add about 10 parts by weight, and unless a large amount is used, it is not effective.

As a result of further research and improvement, the inventor of the present application has a performance equivalent to that of the resin composition previously proposed by adding a small amount of fine particles of calcium silicate instead of the above melamine phosphate and melamine borate. It was found that a flame-retardant resin composition can be obtained.

That is, the flame-retardant resin composition according to the present invention is a mixture of (a) a vinyl chloride resin and a polymer compound compatible with the vinyl chloride resin.
Mixtures added up to 50 parts by weight, (b) One or two molybdenum compounds selected from metal salts of molybdic acid added in the range of 2 to 40 parts by weight with respect to 100 parts by weight of vinyl chloride resin. The above is characterized by comprising (c) fine particles of calcium silicate added in an amount of 0.2 to 5 parts by weight with respect to 100 parts by weight of the vinyl chloride resin.

If necessary, external plasticizers, heat stabilizers, lubricants, antioxidants, UV absorbers, organic polymer processing aids, inorganic fillers, inorganic and organic flame retardants can be added. The resin composition of the composition has excellent flame retardancy, oil resistance,
It has thermal deformation resistance and can be widely used for building materials, wall materials for vehicles, etc., electric wires, cables, etc.

Examples of the vinyl chloride resin that forms the resin mixture of the above (a) include vinyl chloride resin and copolymers of vinyl chloride and vinyl acetate, ethylene, propylene, vinylidene chloride, acrylic acid ester, etc. Or two or more kinds are used. As the polymer compound compatible with the vinyl chloride resin, some of the above-mentioned ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate-carbon monoxide polymers are mentioned. , Ethylene-acrylic acid ester-carbon monoxide copolymer, acrylonitrile-butadiene rubber, chloroprene rubber, chlorinated polyethylene, acrylic acid ester copolymer, etc. are exemplified, and one or more of them are used. The polymer compound is added in an amount of 150 parts by weight or less, preferably 20 to 100 parts by weight, based on 100 parts by weight of the vinyl chloride resin, and the mixture has excellent oil resistance and heat distortion resistance.

An external plasticizer can be added to adjust workability and cold resistance. However, addition of such a low molecular weight organic substance causes the components to explode during flame contact, causing smoke and shrinkage, as well as burning residue. Since it is difficult to form a dense foamed carbonized layer due to cracking easily, it is desirable to keep it in a small amount.

Examples of the moybden compound (b) include ammonium molybdate, calcium molybdate, zinc molybdate, lead molybdate, and the like. One or two or more of these molybdic acid metal salts are vinyl chloride resin 100
2 to 40 parts by weight to 10 parts by weight is generally added. In addition, such a molybdenum compound may be used by supporting it on an inorganic compound such as calcium carbonate, talc, asbestos, clay or aluminum hydroxide.

A molybdenum compound is known as a substance that, when used together with a flame retardant such as antimony trioxide, raises the oxygen index and at the same time produces a smoke suppressing effect. It also has the function of expanding and expanding the resin during flame contact. Since the carbonized layer is simply formed by melting and expanding the resin, it is fragile and easily cracks, and heat cannot penetrate through the cracks to protect the inner layer material.

The present invention is one in which fine particles of calcium silicate are added as described in (c) above, whereby a stable foamed carbonized layer which is dense and does not cause cracks is formed.

As fine particles of calcium silicate, petal-like shape with a length of 1 to 5μ, scaly shape with a length of 3 to 50μ, and length of 20 to 300μ
A fibrous material of a certain degree is suitable, and one or more kinds thereof are used, but a petal-shaped material having an extremely large specific surface area of about 100 to 450 m ² / g is optimal. Such fine particles not only cause no cracks in the foamed carbonized layer at high heat, but also do not cause cracks when contracted, and the amount is 0.
2 to 5 parts by weight, preferably 0.5 to 4 parts by weight.

Fine particles of silicic acid anhydride are also effective in preventing the occurrence of cracks in the foamed carbonized layer, but they are not used because they have hygroscopicity and lose their effect when stored for a long time.

Next, the test results of the comparative example and the example of the present invention will be described.

A UL standard model 1365 coaxial cord (conductor size 20 AWG) is used as a comparative example in which calcium silicate particles (manufactured by Tokuyama Soda, Fluorite R) are not added to the following composition (parts by weight) as an example. I made five each.

Ethylene-Vinyl Chloride Copolymer 100 (Sekisui Tokuyama Sekisui PVC VE-K) Ethylene-Vinyl Acetate-Carbon Oxide Terpolymer
70 (Mitsui Petrochemical, Elvalloy 742) Antimony trioxide 20 Zinc borate 20 Calcium carbonate 20 Zinc molybdate coated calcium carbonate 20 Barium zinc stabilizer 6 Lubricant 2 Sample is vertical to the tyryl-type burner specified in UL standard 62 In this state, the operation of indirect flame for 15 seconds and flame separation for 15 seconds was repeated 5 times, and if the burning time of each time was within 60 seconds, it was judged as pass, and if it was longer than that, it was judged as fail. The following table shows the combustion time and the judgment result by this combustion test.

(Comparative example) (Example, 1 part of calcium silicate) (Example, 2 parts of calcium silicate) (Example, 3 parts of calcium silicate) (Example, 4 parts of calcium silicate) (Example, 5 parts of calcium silicate) Further, the following table shows the results of carrying out a combustion test by storing the samples of the examples in an atmosphere of 80% relative humidity for 20 days.

(Example, 1 part of calcium silicate) (Example, 2 parts of calcium silicate) (Example, 3 parts of calcium silicate) In each of the above tests, it was confirmed that the foamed carbonized layer formed by the flame contact did not crack in the samples of the examples.

From the above, not only the resin composition of the present invention has excellent flame retardancy, but the foamed carbon layer formed by flame contact is stable without cracks and has excellent heat insulation for the inner layer material. Moreover, it is understood that the fine particles of calcium silicate have no hygroscopicity and do not lose their effect even after a long period of time.

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Claims (2)

[Claims] 1. A mixture of (a) a vinyl chloride resin and a polymer compound compatible therewith, wherein the latter is added in an amount of 150 parts by weight or less to 100 parts by weight of the former, and (b) a vinyl chloride resin. One or more molybdenum compounds selected from metal salts of molybdic acid added in an amount of 2 to 40 parts by weight based on 100 parts by weight of the resin, and (c) 0. A flame-retardant resin composition comprising: fine particles of calcium silicate added in an amount of 2 to 5 parts by weight. 2. The maximum length of fine particles of calcium silicate is 5
The flame-retardant resin composition according to claim 1, which comprises one or more types of petals in a size of not more than μ, scales of not more than 50 μ, and fibrous not more than 300 μ.