JPS61228043A - Electron beam irradiation crosslinked polyolefin composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to an electron beam irradiation crosslinked polyolefin composition.

[Conventional technology]

Polyolefins are widely used due to their excellent electrical and mechanical properties, but depending on the usage environment, improvements in heat deformation resistance, mechanical properties, chemical resistance, etc. may be required. For this purpose, crosslinking is usually performed.

One such crosslinking method is the electron beam irradiation method, which is much more efficient than steam crosslinking methods, especially for thin coating materials such as thin insulated wires used in equipment wiring. Because of its advantages, electron beam irradiation is mainly used, at least in this field.

In order to use polyolefin in -a in a high-temperature atmosphere, it is important to improve heat deformation resistance through crosslinking and at the same time improve heat aging resistance. Crosslinking accelerators and heat aging inhibitors have been added to resins to increase crosslinking efficiency. The crosslinking accelerator is, for example, trimethylolpropane trimethacrylate (hereinafter abbreviated as TMPT), and the heat aging inhibitor is 4,4'-thio-bis(6-t-butyl-m-cresol) (hereinafter, abbreviated as TMPT). (abbreviated as phenolic anti-aging agent) is used.

[Problem that the invention seeks to solve]

However, when conventional crosslinking accelerators and heat aging inhibitors are used together with polyolefins, the following problems arise. That is, (1) the crosslinking promoting effect of TMPT is not so great.

lower it further.

- TMPT has poor affinity and tends to cause a bleed phenomenon.

It is.

c.Means for Solving Problems] In order to solve the above problems, this invention adopts a method of blending diallyl chlorendate as a crosslinking accelerator for polyolefin resin together with a heat aging inhibitor. be.

〔Example〕

The polyolefin referred to in this invention means, for example, C8-C
1, a C1-C1 diene monomer, an ethylene vinyl acetate copolymer, an ethylene ethyl acrylate copolymer, and a mixture thereof.

In addition, the diallylchlorendate referred to in this invention has the effect of promoting dehydrogenation reaction from polymer chains and promoting crosslinking reaction during electron beam irradiation, and has a very high affinity with the following chemical structural formula. Disperses well. In the present invention, it is desirable that the amount of diallyl chlorendate added is 0.5 to 5 parts by weight per 100 parts by weight of the polyolefin. This is because if the amount added is less than 0.5 parts by weight, no crosslinking promoting effect will be observed, whereas if the amount added exceeds 5 parts by weight, not only will there be no improvement in the crosslinking promoting effect, but also a bleeding phenomenon will occur, resulting in a decrease in commercial value. This is because it significantly reduces the

Next, as the heat aging inhibitor in this invention, in combination with the above-mentioned crosslinking accelerator, 2-Mel + Go 1 Beso 47>
J'*f -jl or 2-mercapto-methyl-benzimidazole is preferable, and these compounds prevent polyolefin aging due to oxygen during electron beam irradiation in air, and also prevent the bleed phenomenon without inhibiting the crosslinking reaction. It has a very remarkable effect on heat aging resistance.The amount of such heat aging inhibitor is preferably 2 to 30 parts by weight per 100 parts by weight of polyolefin. If the amount of the inhibitor is less than 2 parts by weight, it is insufficient to improve heat resistance; on the other hand, if the amount is more than 30 parts by weight, no effect can be expected by increasing the amount.
This is because the mechanical properties deteriorate significantly, which is undesirable.

Now, the following standard composition, namely (weight) (1) Linear low-density polyethylene (manufactured by Nihon Nijika Co., Ltd.;

O3-650) Old... 80 parts (2) Ethylene-ethyl acrylate copolymer (manufactured by the same company? DPDJ-6182) - 20 parts as a flame retardant and flame retardant aid, (3) Decabromodiphenyl ether ( Mitsui Fine Chemical Co., Ltd. Nibraneron DB-102) --- 5
0 parts (4) Antimony dioxide...
...201M5 Furthermore, as a processing aid (5) Zinc white...5
8 parts (6) Zinc stearate...
... A crosslinking accelerator and a heat aging inhibitor were blended into the second part in the proportions shown in Table 1 (Examples 1 to 10), and the raw materials on each side were mixed with 150 to 180% by mixing roll.
After heating and kneading at ℃, gauge pressure 150 kg 10 J, 18
Press molding was performed at 0°C for 10 minutes to produce a sheet with a thickness of 0°5fl, and the obtained sheet was irradiated with electron beams in air at an acceleration voltage of 750 keV and 44-A. The amount of electron beam irradiation at this time was 20 Mrad in each case, and the tensile strength/strength and elongation (%) of the sheet after the electron beam irradiation were measured. For sheets after electron beam irradiation, the tensile strength and elongation after a heat aging test held in an air heat aging tester at 158°C for 7 days in accordance with the UL standard's 125°C rating evaluation method are calculated based on the heat aging test. The results were determined in the form of residual percentage (%) with respect to the value before the aging test, and the obtained results are summarized in Table 1 along with the gel fraction (%) after electron beam irradiation, presence or absence of bloom phenomenon, etc. In crosslinked polyolefins, the gel fraction increases as the degree of crosslinking increases, and the heating degree decreases as well.
After immersing at 0°C for 24 hours, it was dried at 120°C for 24 hours, and the weight gel fraction after drying (%) - X100 weight before immersion was determined. In addition, in the same table, rTMPTJ is trimethylolpropane trimethacrylate as mentioned above, and "phenolic anti-aging" is 4.4°-thio-bis(6-
t-butyl-m-cresol).

In addition, in contrast to this, crosslinking accelerators and heat aging inhibitors were added to the standard formulations of Examples 1 to 10 in the proportions shown in Table 2 (Comparative Examples 1 to 7) Table 2, gel fraction ,TMPT,
Phenolic anti-aging agents are the same as in Table 1. The sheet manufacturing conditions, electron beam irradiation conditions, and physical property measurement methods were all the same as in the previous example, and the obtained results were summarized and listed in Table 2. However, the physical property values shown in Table 2 were Comparing with those in the table, Comparative Example 1 has elongation after heat aging test, Comparative Example 2 has tensile strength after irradiation, and Comparative Example 3 has tensile strength after irradiation. 4. 5 shows the lead phenomenon, Comparative Example 4 shows the elongation after heat aging test, and Comparative Example 5 shows the elongation after heat aging test.
It can be seen that Comparative Example 6 is significantly inferior in elongation after irradiation, gel fraction in Comparative Example 6, and comparative example 7 in terms of tensile strength after irradiation, gel fraction, elongation after heat aging test, and bleeding phenomenon.

〔effect〕

As described above, the present invention provides electron beam irradiation that exhibits good results not previously achieved in terms of excellent crosslinking promotion effects, mechanical properties such as tensile strength and elongation, heat aging resistance, and bleed resistance. The following margin procedure amendment (Ku) May 25, 1985

Claims (4)

[Claims] (1) An electron beam irradiation crosslinked polyolefin composition characterized in that a polyolefin is blended with diallyl chlorendate as a crosslinking accelerator and a heat aging inhibitor. (2) The electron beam irradiation crosslinked polyolefin composition according to claim 1, wherein the diallyl clodendate is a compound represented by the formula ▼ where n=1 to 4. (3) The electron beam irradiation crosslinked polyolefin composition according to claim 1, wherein the heat aging inhibitor is 2-mercaptobenzimidazole or 2-mercapto-methyl-benzimidazole. (4) The blending ratio of polyolefin, diallyl chlorendate, and heat aging inhibitor is 100 parts by weight each;
0.5 to 5 parts, and 2 to 30 parts of the electron beam irradiation crosslinked polyolefin composition according to claim 1.