JPS6058256B2 - Flame retardant synthetic resin composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to a flame-retardant synthetic resin composition.

More specifically, the present invention relates to a crosslinked flame-retardant synthetic resin composition obtained by adding a flame retardant to a base resin mainly composed of a polyolefin resin and silicone-modified ethylene propylene rubber (hereinafter referred to as SEP rubber). An object of the present invention is to provide a flame-retardant synthetic resin composition that prevents the resin from melting and falling during combustion and has excellent electrical properties, mechanical properties, thermal stability, and processability. It is in.

In general, polyolefin resins have electrical properties, weather resistance,
It has excellent chemical resistance and processability, and is widely used in various fields. However, on the other hand, it has the disadvantage that it is easily flammable, so there is a built-in risk of causing a fire accident when it is used. be. Conventionally, the method of making synthetic resin flame retardant has been to add flame retardants, and known flame retardants include halogen-based, phosphorus-based, nitrogen (filler), etc. There is.

Flame retardant polyolefin resins can be made flame retardant by adding the flame retardant mentioned above, but underwriters, Laboratories, Inc. (UND)
ERWRITERS LABORATORIES INC.
) combustion test standard for plastic materials UL94 [TES
TFORFLAMMABILITY OF PLASTIC
MATERIALS-UL94 (FEBRUARYI,
1974)] vertical fuel test (VerticalBur
ningTestforClassifyingMat
erials94V-O, 94V-1or94V-2,
In order to pass the test for the presence or absence of falling molten combustible resin that could ignite the absorbent cotton placed under the sample during combustion (hereinafter referred to as UL-94), a larger amount than the commonly used flame retardant additive is required. requires the addition of
The disadvantage is that the electrical properties, mechanical properties, thermal stability, and processability of the resulting flame-retardant synthetic resin are significantly reduced.

Therefore, the present inventors have conducted extensive research in order to eliminate the above-mentioned drawbacks and provide a flame-retardant synthetic resin composition that has the flame resistance to pass the severe vertical combustion test and has excellent resin properties. As a result, by adding an appropriate amount of flame retardant to the base resin mainly composed of polyolefin resin and SEP rubber, it was possible to meet the harsh vertical combustion test standard U.
It was confirmed that L-94 also prevents the resin from melting and falling during combustion, and that a flame-retardant synthetic resin composition can be obtained that has resin properties that are excellent in electrical properties, mechanical properties, thermal stability, and processability. This led to the completion of the present invention. That is, the present invention relates to a crosslinked flame-retardant synthetic resin composition characterized by blending an appropriate amount of a flame retardant into a base resin of a polyolefin resin and silicone-modified ethylene propylene rubber (SEP rubber).

Conventionally, as a method for preventing melting and falling of resin during combustion, a method of adding an inorganic filler to resin (Japanese Patent Laid-Open No. 51-14
933 Unagi Publication) and a method of adding silicone rubber (Japanese Unexamined Patent Publication No. 73943/1983) have been proposed.

However, when using an inorganic filler, it is necessary to add a large amount, which reduces the mechanical properties of the resulting resin (such as tensile strength and elongation), and generates die slag in the die slot during extrusion processing. The die slag then adheres to the surface of the extruded product. In addition, inorganic fillers are generally hygroscopic and have the disadvantage of deteriorating electrical properties (eg, insulation resistance).

On the other hand, when silicone rubber is used, there is a natural limit to the amount of silicone rubber added due to its poor compatibility with polyolefin resins. Moreover, it has the disadvantage that it cannot be added in a large amount, has poor dispersibility, and has poor mechanical properties and kneading processability. On the other hand, the flame-retardant synthetic resin composition of the present invention has the following characteristics. Meets the harsh vertical combustion test standards of UL without the addition of inorganic fillers.
-94 also prevents the resin from melting and falling during combustion, and avoids deterioration of resin properties caused by the addition of inorganic fillers, and since SEP rubber has an ethylene-propylene skeleton in the main chain, it is similar to polyolefin resins. It has excellent compatibility and can sufficiently cover the drawbacks of conventional resins obtained by preventing melting and falling. Examples of the SEP rubber include ethylene-propylene copolymer elastomers such as ethylene-propylene rubber modified by bonding organopolysiloxane, ethylene-propylene copolymer, and ethylene-propylene-diene terpolymer. It will be done. In addition, the flame-retardant synthetic resin composition of the present invention can improve the above-mentioned properties, and since SEP rubber is mixed with the polyolefin resin, generation of die slag during extrusion processing can be prevented and thermal stability can be improved. Not only is the resin melted and dropped during combustion, but also the oxygen index is 101.
resistance to combustion and fire can be improved.

In the flame-retardant synthetic resin composition of the present invention, polyolefin resin and SEP rubber are used as the base resin as described above, but the amount of SEP rubber used is The silicone content in the SEP rubber is set at an amount equivalent to 0.2 to 9% (by weight, hereinafter the same) based on the total resin content (including SEP rubber), which gives extremely good resin properties. It can be done.

When the silicone content in the SEP rubber is lower than the above content, melting and falling of the resin during combustion cannot be prevented, and extrusion processing characteristics (prevention of die slag generation) and heat resistance are improved. Moreover, when the amount exceeds the above-mentioned content, the electrical properties, especially the insulation properties, of the resulting resin composition are significantly reduced, which is not preferable. However, if an improvement in electrical insulation is not desired, there is no problem even if the content exceeds the above. The polyolefin resin used in the present invention is a polyolefin polymer polymerized by a high pressure method or a low pressure method using a catalyst, and typical examples thereof include polyethylene, polypropylene, polybutylene, polypentene, and copolymers thereof. Alternatively, modified polymers mainly composed of these may be mentioned.

The modified polymer here refers to other α-
These are copolymers of olefins and vinyl compounds, or mixtures of other polymers. Examples of the copolymer or modified polymer include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, and ethylene-propylene-diene terpolymer. Flame retardants used in the present invention include perchloropentacyclodecane, dodecachlorododecahydrodimethanodibenzocyclooctene, dodecachlorooctahydrodimethanodibenzofuran, decapromodiphenyl oxide, 2,2-bis(4-hydroxy 3,5-dibromophenyl)pentane, hexabromobenzene, tetrabromobisphenol A1 pentabromotoluene, decabromodiphenyl ether, pentabromophenol, tris(2,3-dibromopropyl)-
Examples include halogen flame retardants such as isocyanurate and 2,2-bis(4-hydroxyethoxy-3,5-dibromophenyl)propane, and one or more of these may be used.

Note that it is desirable to use two or more of these flame retardants in combination from the viewpoint of electrical properties. In addition, if electrical properties are not important, phosphorus-containing organic compounds such as triphenyl phosphate and tricresyl phosphate, halogen-containing phosphorus-containing organic compounds such as tris(2,3-dibromopropyl) phosphate, ammonium polyphosphate, etc. Phosphorous flame retardants such as nitrogen-containing phosphorus-containing organic compounds, amide compounds, N-
Nitrogen-based flame retardants such as chloro-N-nitroso organic compounds, boron-based flame retardants such as zinc borate and barium metaborate, and inorganic hydrates such as magnesium hydroxide and aluminum hydroxide can also be used. Further, as the flame retardant aid, conventionally known antimony oxide, zircoconium oxide, etc. are used.

In addition to the above-mentioned basic components, the flame-retardant synthetic resin composition of the present invention contains fillers, pigments, stabilizers, crosslinking agents, and other conventional additives such as anti-aging agents, modifying agents, etc., which are usually added to polyethylene resins. A release agent, mold release agent, etc. can be contained. In the flame-retardant synthetic resin composition of the present invention, the base resin is a heat-activated crosslinking agent (hereinafter referred to as a crosslinking agent).
The base resin is crosslinked by or by irradiation, and the crosslinking agents used include benzoyl peroxide,
Di-Tel-butyl peroxide, dicumyl peroxide, 2,5-? Methyl-2,5-di(Tert-butyl)-hexane, 2,5-dimethyl-2,5-di(T
tert-butylperoxy)-hexyne, 1,3-bis(tert-butylperoxyisopropyl)benzene, tert-butyl hydroperoxide, cumene hydroperoxide, polysulfone azide, azido formate, tetramethylisophthaldi-tert-butyl bisper Oxide, tetramethylisophthalyl diwalnut bisperoxide, etc.

The amount of such a crosslinking agent used is usually 0.5 to 5 parts (parts by weight, hereinafter the same) per 1 (1) part of the resin (base resin).
Department will be hired. Further, for irradiation crosslinking, an irradiation source such as a high-energy electron beam or an X-ray may be appropriately employed. In the flame-retardant synthetic resin of the present invention, since the amount of filler added is smaller than that of conventional resins, the irradiation effect is extremely good.
Therefore, the flame-retardant synthetic resin composition of the present invention has polyolefin resin, SEP rubber, and flame retardant as basic components, and other conventional additives as required by a conventional blending method (for example, using a Pan Bali mixer or a two-stage roll mill). etc.), the ingredients are first kneaded at a temperature sufficient to soften and plasticize the base resin, and are substantially uniformly dispersed.

When a crosslinking agent is used, after the kneading, the temperature of the mixed batch is lowered to below the decomposition level of the crosslinking agent used,
It is then preferable to add a crosslinking agent to this and uniformly disperse it. Then, during molding, the compound containing a crosslinking agent is heated to a level above the level at which the crosslinking agent decomposes, or during molding, a compound that does not contain a crosslinking agent is irradiated to crosslink, and finished into covering materials, molded parts, etc. The flame-retardant synthetic resin composition of the present invention can be advantageously used, for example, in the production of electrical wires, insulating coating materials (body) for communication cables, insulators for wiring materials in electronic devices, and the like.

The flame-retardant synthetic resin composition of the present invention has excellent electrical properties, mechanical properties, processability, etc. as described above, and also passes the vertical combustion test (UL-94), and the resin melts and falls during combustion. It is extremely useful as the phenomenon is not obvious.

Next, the flame-retardant synthetic resin composition of the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Examples 1 to 3 MIRAS0N-9 (low density polyethylene manufactured by Mitsui Polychemical Co., Ltd.), SEP-142U (manufactured by Shin-Etsu Chemical Co., Ltd.)
Silicone-modified ethylene propylene rubber (silicone content: 30%), Dechlorane Plus (chlorinated flame retardant manufactured by HOOker Chemical), antimony trioxide, anti-aging agent, stabilizer, filler and a crosslinking agent in the proportions shown in Table 1.
After sufficiently dispersing by kneading on a roll at 0 to 130°C, this was heated and pressurized (crosslinked) at 175°C for 15 minutes,
Sheets each having a thickness specified by each test method described below were produced.

The electrical properties of the sheet thus produced were determined according to JISK67.
2 Nu oxygen index is JISK72Ol, mechanical properties are JIS
The presence or absence of melting and falling of K676O and resin during combustion was measured in accordance with UL-94.

Regarding heat resistance, a test piece was prepared from this sheet according to the JIS K676O tensile test method, and heat aged in a gear open aging tester at 150°C until the sample's embrittlement point (elongation rate 100%) was reached. The number of days of aging was measured.
Regarding extrusion processability, pellets of the sheet resin were processed using a Brabender extruder (manufactured by BraberKier) at a die part of 110°C, a screw part of 120°C, a hopper part of 120°C, and a screw rotation speed of 6 (
2) Judgment was made by the presence or absence of die slag after extruding 3 powders at a rotation/l minute rate. The results of these measurements are shown in Table 2.

Also, Comparative Examples 1 to 3.15. Sheets having the thickness specified by each test method were prepared in the same manner as in Examples 1 to 4 using the blending ratios shown in Table 1, and their resin properties were measured.

Claims (1)

[Claims] 1. A crosslinked flame-retardant synthetic resin composition comprising a base resin of polyolefin resin and silicone-modified ethylene propylene rubber mixed with an appropriate amount of a flame retardant.