JPS5898347A - Heat-resistant, fire-retardant crosslinking blend - Google Patents

Abstract

PURPOSE:To provide the titled blend useful for wire covering and other moldings, by incorporating a fire retardant with a thermoplastic elastomer consisting mainly of polypropylene and a block copolymer with a structure of styrene/ ethylene/butylene/styrene. CONSTITUTION:A fire retardant (e.g., a chlorinated fire retardant, antimony trioxide) and SEBS with a structure of styrene/ethylene/butylene/styrene (e.g., Krayton G1652, a product of Shell Chem. Co.) are added to polypropylene, yielding a crosslinking blend with heat resistance and satisfactory fire resistance. Compsns. of fire retardant and SEBS are pref. 60-120pts.wt. and 20-50pts.wt., respectively, based on 50-80pts.wt. polypropylene and, as required, an antioxidant, a stabilizer and a crosslinking assistant also are added each in 2- 20pts.wt., relative to the above pts.wt. of polyproylene, fire retardant, and SEBS.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant flame-retardant cross-linked 1iIa mixture, particularly a polyglobuly(P-a)t-based nine-S hydrate. In general, when polypropylene is crosslinked, Compared to crosslinked polyethylene (PI), polypropylene has a high degree of heat resistance and excellent mechanical properties, but due to its molecular structure, polypropylene deteriorates at the same time as crosslinking. However, a sufficient cross-linking method has not yet been established, and the current situation is that the reaction involves a reaction of 0.

Therefore, the present inventors have developed a method that has heat resistance and sufficient al1.
When cross-linking of polypropylene was extensively studied in order to obtain a cross-linking compound having a flame temperature of 1, the following results were obtained.

That is, the main angle −,ms is first used as an index of deterioration,
Focusing on the elongation of the 1l AIll product, we looked at the relationship between this elongation and Hata 1m&, and found that the gel fraction (m constant conditions, 120°C
, xyl・n・, after being immersed for a period of time, is crosslinked and the nine portions gel and remain, so this gel fraction (corresponding to the approximate degree of crosslinking) is ~4oX, which is the initial value. The next step is to obtain a crosslinked product with a satisfactory elongation of 300 to 400 N.

However, this product underwent a combustion test (ULal direct combustion test:
If m fuel ta is added until it passes VW-1), the elongation will be 100! It will drop below X.

Therefore, in addition to polypropylene KJII fuel, various thermoplastic elastomers were added, and the elongation t after crosslinking was
aoo~500%90 However, for these mixtures, the heat resistance
× 7 days heat death , the residual elongation is θ~3o We discovered that it was necessary to use plastic elastomers (hereinafter referred to as AMMS).

The present invention has been made based on the above-mentioned points, and the object thereof is to create a polypropylene-based compound having heat resistance and sufficient flammability as described above. The object of this invention is to add BIAB8T to polypropylene in addition to a flame retardant.

Styrene-ethylene-butylene used in the present invention
Examples of 1311B8 having the structure tV of styrene include, but are not limited to, Kraton 01652 (trade name,
Shell Chemical Co., Ltd. 11) t- can be mentioned. Also, J
As the IIm agent, for example, chlorine-based retardant, bromine-based retardant, antimony dioxide, and soybean chloride can be used.And the blending ratio of each of these compositions is polypropylene groups ~800 The retardant is ω~120
Parts by weight, 811BB, are preferably parts by weight. That is, if the llAl1la agent is less than 1 part per 1 part, sufficient flammability cannot be obtained, and if it exceeds 120 parts by part, the bone properties and other bone properties such as elongation will deteriorate undesirably. On the other hand, in the case of 813IO, if it is less than 20x parts, it is not possible to achieve a residual elongation ratio of 170x or more, and even if it exceeds 5011 parts, it is not expected to improve the elongation ratio much. In addition to the above one & composition O, it is a must! Depending on the situation, stabilizers such as antioxidants and copper inhibitors,
In that case, the blending ratio is the above-mentioned polypropylene, fuel, 81BE
2 to 2 parts by weight of antioxidants and stabilizers
0 parts by weight, and the crosslinking aid is also preferably 2 to 20 parts by weight.

Further, as a means for crosslinking the mixture of the present invention, electron beam irradiation,
Any known chemical crosslinking may be used, but for example, for thin materials, electron beam irradiation may be used, but for thick materials, beam chemical crosslinking is preferable. The use of the heat-resistant heavy-state crosslinked mixture is not limited to bones, but it can also be used as a covering material for electric wires, as well as heat-shrinkable tubes, ordinary molded products, sheets, etc.

Next, examples of the present invention will be described.

The compounding ratio of each example of the present invention is shown in Table 1 below.
Seven's fr'ie sex is #! It is like 2 narrow.

For comparison, in the case of only polypropylene, the following mixtures with ethylene-α-olefin copolymer or isopre rubber added are also shown as comparative examples.

According to each of the above-mentioned machines, in each embodiment of the present invention, 8]l
It can be seen that since B8 was added, there was almost no decrease in the residual elongation rate. That is, enough S to pass VW-IK.
In addition to having a high degree of twist, it is possible to obtain a mixture that has a high degree of heat resistance with a usable temperature of 150°C. On the other hand, when using only polypropylene, there is almost no elongation,
Furthermore, it can be seen that when isoprene rubber is added to the ethylene-α-olefin copolymer, the residual elongation after the heat test is significantly reduced. As is clear from the description, according to the present invention, in addition to the heat retardant, polybupylene is crosslinked by adding BIIIB87, so that it has a sufficient degree of heat, and at the same time,
^[40 It is now possible to obtain a heat-resistant and heat-retardant crosslinked mixture based on polypropylene that has excellent heat resistance and excellent mechanical properties.

Claims (1)

[Claims] 1. A heat-resistant, flame-retardant mixture comprising a thermoplastic elastomer mainly composed of a block copolymer having the structure t- of polyethylene, styrene-ethylene-butylene-styrene, and a flame retardant.