JPS61235448A - Heat-resistant polyvinyl chloride resin composition - Google Patents

Abstract

PURPOSE:To provide a resin compsn. which is inexpensive and excellent in heat resistance, by irradiating a resin compsn. contg. a polyvinyl chloride resin having a high degree of polymn., a pyromellitate ester plasticizer, a lead stabilizer and an antimony compd. with an ionizing radiation to crosslink it. CONSTITUTION:100pts.wt. polyvinyl chloride resin having a degree of polymn. of 2,000 or above, 70-150pts.wt. pyromellitate ester plasticizer (e.g. tri-n-octyl pyromellitate), 2-30pts.wt. lead stabilizer (e.g. tribasic lead sulfate) and 5-20pts. wt. antimony compd. selected from among antimony trioxide, antimony pentoxide and sodium antimonate are uniformly mixed together. The resulting compsn. is irradiated with an ionizing radiation to crosslink it, thus obtaining the desired heat-resistant polyvinyl chloride resin compsn. The resin compsn. is suitable for use as an insulator for wires.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel heat-resistant polyvinyl chloride resin composition.

Conventionally, plasticized polyvinyl chloride compositions have been widely used because they are inexpensive and have excellent flame retardancy and moldability. Furthermore, when used as an insulator for electric wires, insulating tubes, etc., heat resistance is required.

However, polyvinyl chloride compositions have conventionally had a limited thermal deterioration property, so there has been no one with better heat resistance than 105°C. For this, the temperature is 105°C
Cross-linked polyolefin resins are used in higher-temperature applications, but adding flame retardancy to polyolein resins causes problems such as high cost and reduced moldability, which ultimately leads to considerable problems. It ends up being expensive.

By the way, as a method for improving the heat resistance of the above-mentioned plasticized polyvinyl chloride composition, heat deterioration characteristics can be improved by using a plasticizer with good heat resistance and a highly effective stabilizer, specifically a lead-based stabilizer. Also, as the mechanical strength decreases significantly at high temperatures of 100°C or higher, it is possible to crosslink and modify the mechanical strength at high temperatures using irradiation crosslinking using ionizing radiation or chemical crosslinking. It has been done. Furthermore, to achieve the current maximum temperature of 105°C, trimellitic acid ester plasticizers have been mainly used as plasticizers, but in order to improve heat resistance, trimellitic acid ester plasticizers are more volatile than trimellitic acid ester plasticizers. Pyromellitic acid ester plasticizers with low properties have been studied. However, despite such studies, pyromellitic acid ester plasticizers have a
Heat resistance improved only at ℃.

Therefore, as a result of various studies, the present inventors found that the degree of polymerization was 20.
For 100 parts by weight of vinyl chloride resin with a high polymerization degree of 00 or more, 2 to 30 parts by weight of a lead-based stabilizer, 70 to 150 parts by weight of a pyromellitic acid ester-based oxidizing agent, and further antimony pentoxide, When an antimony compound selected from antimony oxide and sodium antimonate is blended in a large amount of 5 to 20 parts by weight, surprisingly, for example,
The 40,000-hour heat resistance temperature specified in the Electrical Appliance and Material Standards' ``Upper Temperature Limit for Insulating Materials Used in Electrical Appliances'' is 11.
It has been found that the composition exhibits an unprecedentedly high heat resistance of around 5°C. This is because, at such high temperature levels, the heat resistance of polyvinyl chloride resin compositions is affected not only by volatilization of the plasticizer, which was dominant at lower temperatures, but also by the composition system, including the resin and stabilizers. Although the detailed cause is unknown, the combination of high polymerization degree polyvinyl chloride resin and large amounts of pyromellitic acid ester plasticizer and antimony compound has a favorable synergistic effect. It is thought that the

Here, the polyvinyl chloride resin has a polymerization degree of 200
If it is lower than 0, there is almost no effect. If it exceeds 8,500, the mixing and molding properties will deteriorate, so the degree of polymerization of the resin is preferably 2,000 to 8,500. Regarding the amount of pyromellitic acid ester plasticizer added, it is effective if it is 70 parts by weight or more, but if it exceeds 150 parts by weight, the mechanical strength and electrical properties will be significantly reduced. However, the range in which the effect on heat resistance is highest is in the range of 90 to 130 parts by weight. The amount of plasticizer added to the usual plasticized polyvinyl chloride resin is 50 parts by weight of 8ON. Such pyromellitic acid ester plasticizers are preferably those made from alcohols having 6 or more carbon atoms, and tri-n-octyl pyromellitate or tri(2-ethylhexyl) pyromellitate are easily available. On the other hand, the amount of the antimony compound added is 5
If the amount is less than i part, there is no effect, and if it exceeds 20 parts by weight, the effect is saturated, and further improvement in the effect is not desired, and it becomes expensive and uneconomical.

However, pigments, inorganic fillers, polyfunctional crosslinking accelerators, flame retardants, etc. can be added to the composition of the present invention. In particular, the crosslinking accelerator can reduce the irradiation dose of electromorphic radiation, thereby preventing radiation deterioration of the composition and bringing about good results in maintaining heat resistance.

Hereinafter, the present invention will be further explained by comparing it with a comparative example.

Examples 1 to 10, Comparative Examples 1 to 7 Each composition was mixed in a roll mill at 130°C for about 10 minutes at the ratio of the composition (f [part f)] listed in Table 1, and then formed into a sheet. I made it. Subsequently, the sheet-like composition was crushed with a pelletizer to obtain pellets. Next, the pellets were molded into a 25fiφ, I4/D-22 small extruder with an inner diameter of 1.51111φ at a die temperature of 130°C.
A tube having an outer diameter of 2.4 mm and a uniform thickness was made. Subsequently, using an electron beam irradiator with an acceleration energy of 500 K6V, the tube was uniformly irradiated with 10 Mrad to effect crosslinking. The thus produced tube-shaped composition molded body was aged at temperatures of 135°C, 150°C, and 160″C, and Measure the elongation of the tube by taking regular samples in accordance with the
% (lifetime) was determined for each temperature. Next, the heat resistance temperature for 40,000 hours was determined by extrapolating this value using a Reus plot and a regression line. Q.The tension conditions are tension speed 200/min, standard distance 20
It was a parrot. This 40,000 hour heat resistance temperature and initial tensile strength,
The elongation is also listed in Table-1.

As is clear from Example 1.2.3 and Comparative Example 8, the degree of polymerization of polyvinyl chloride resin is related to heat resistance.
When the degree of polymerization was 1450, the heat resistance was 108°C, whereas when the degree of polymerization was 2100 or more, the heat resistance was around 115”C.

Furthermore, as is clear from Examples 2, 4, 5 and Comparative Example 6, when the amount of pyromellitic acid plasticizer added was 50 parts by weight, which is the usual amount, the heat resistance was 108°C. Yes, but 3
When it was increased to 0 parts by weight, it was dramatically improved to 112 parts by weight.
It has become ℃. When the amount was further increased to 1001 L parts and 150 parts by weight, the heat resistance was further improved to around 115°C. However, when the amount of plasticizer added increased to 150 parts by weight, there was a tendency that the tensile strength decreased significantly. On the other hand, although a large amount of a pyromellitic acid plasticizer was similarly blended into an ordinary polyvinyl chloride resin having a degree of polymerization of 1450, there was no significant improvement in heat resistance (Comparative Examples 1 and 2).

Next, regarding the antimony compound, Example 6#7゜25,
As shown in Comparative Example 7, if the amount of antimony trioxide added is about 2 parts by weight, which is the usual amount, the heat resistance will not be improved sufficiently, but if the amount added is 7 parts by weight or more, the heat resistance will be improved at around 115°C. It showed heat resistance.

Good heat resistance was also obtained with antimony pentoxide (Example 9). On the other hand, when a similar large amount of antimony compound was incorporated in a polyvinyl chloride resin having a normal degree of polymerization, the results were not good (Comparative Example δ, 4).

As we have seen above, the good heat resistance of the composition of the present invention is a phenomenon that occurs only when a high degree of polymerization polyvinyl chloride resin, a pyromellitic acid plasticizer, and an antimony compound are blended in large amounts. be.

In addition, polyvinyl chloride resin compositions having such good heat resistance have extremely high industrial utility value due to their low cost and good processability. Polyvinyl chloride straight resin manufactured by Zensha Co., Ltd. Average degree of polymerization 2900 Note 2...
Same as above 2500 Note 8... Same as above
Top 2100 Note 4...Nippon Zeon (
Kao Soap Co., Ltd. Co., Ltd. Company Note 5... Kao Soap Co., Ltd. Bile Agent Tetra n-octylpyromellitate 6...
Same as above

Claims (1)

[Claims] 1. 70 to 150 parts by weight of a pyromellitic acid ester plasticizer and 2 to 30 parts by weight of a lead stabilizer based on 100 parts by weight of a high polymerization degree polyvinyl chloride resin having a polymerization degree of 2000 or more. and further antimony compounds 5 to 2 selected from antimony trioxide, antimony pentoxide, and sodium antimonate.
1. A heat-resistant polyvinyl chloride resin composition, characterized in that it is crosslinked by irradiating ionizing radiation to a polyvinyl chloride resin composition uniformly blended with 0 parts by weight. 2. The amount of pyromellitic acid ester plasticizer is 90~
The composition according to claim 1, characterized in that the amount is 120 parts by weight.