JPS6244583B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a silicon composition that is flame retardant and has X-ray shielding ability, and uses at least platinum or a platinum compound as a flame retardant, and uses barium titanate, barium fluoride, or lead sulfate as an X-ray shielding agent. The object of the present invention is to provide a composition with improved tracking resistance when one or more of these is used. Conventionally, even if attempts were made to impart X-ray shielding ability to silicon compositions, it has been said that the substances contained therein act as catalyst poisons for platinum or platinum compounds, which are the key to the flame retardant mechanism, resulting in the loss of flame retardancy. There was a problem. Therefore, the present inventors first searched for X-ray shielding agents that do not poison the catalyst, and found that barium titanate, barium fluoride, and lead sulfate were non-toxic to the flame retardant mechanism of silicon compositions. I confirmed that there is. However, it has been found that the inclusion of these compounds in a silicone composition may cause a slight decrease in tracking resistance. For example, in the case of silicone rubber, it has a tracking resistance of 100 drops or more under the condition of 800V-1A without containing an X-ray shielding agent. In some cases, the number drops to about 10 to 40 drops, and there is wide variation within that range.
However, under conditions of 750V-1A or less, there is no significant difference from the case without any content. These characteristics vary depending on the type, amount, purity, etc. of the X-ray shielding agent contained. Therefore, the present invention provides a composition that can maintain tracking resistance properties well even when these X-ray shielding agents are contained. Al(OH) ₃ , aluminum oxide Al ₂ O ₃ ,
It is characterized in that it contains one or more of magnesium hydroxide Mg(OH) ₂ and hydrotalcite Mg ₁₈ Al ₆ (OH) ₄₈ (CO ₃ ) ₃ ·12H ₂ O. By containing at least one of these depending on the amount and purity of the X-ray shielding agent, 800V
- Even under conditions of 1A or more, tracking resistance of 100 drops or more can be obtained, which is almost the same as when no X-ray shielding agent is included. It was also experimentally confirmed that the above-mentioned four kinds of tracking resistance improvers do not act as a catalyst poison for the flame retardant mechanism of the silicone composition. Next, examples of the present invention will be described in detail. First, 99.9 mol% of (CH ₃ ) ₂ SiO units and CH ₃ (CH ₂
= CH) ₂ 100 parts of organopolysiloxane raw rubber consisting of 0.1 mol% of SiO units, hume silica (Aerosil 200: trade name, manufactured by Nippon Aerosil Co., Ltd.) 15
1 part, 2.5 parts of diphenylsilanediol as a silica dispersant, 15 parts of powdered manganese carbonate, 7 parts of anatase-type titanium oxide, 0.05 part of a 2% (in terms of platinum) solution of chloroplatinic acid in butanol, and X shown in the table below. A certain amount of the radiation shielding material shown in the table and a certain amount of the tracking resistance improver shown in the table below were weighed and blended, mixed uniformly with two rolls, and then mixed with 150 The mixture was treated at ℃ for 1 hour to obtain a silicone rubber compound, which was used as the base resin of this example. Next, silicone oil paste containing 50% benzoyl peroxide is added to this base range.
A sample was prepared by adding 0.7 parts as a hardening agent and thoroughly kneading with two rolls. These were heated at 120° C. for 20 minutes under a pressure of 50 kg/cm ² and then further heated at 150° C. for 3 hours to prepare sample sheets, and the anti-tracking properties of these sheets were measured by the electrolyte dropping method. In addition, a combustion test was conducted by measuring the combustion time when the material was exposed to flame for 10 seconds under UL94 conditions.

【table】

[Table] As is clear from this result, according to the present invention, it is possible to obtain an excellent silicone composition that fully satisfies all of the X-ray shielding ability, flame retardance, and tracking resistance. It can be effectively used for the anode cap of a television receiver.

Claims (1)

[Claims] 1 Contains platinum or a platinum compound as a flame retardant, contains one or more of barium titanate, barium fluoride, and lead sulfate as an X-ray shielding agent, and contains aluminum hydroxide, aluminum oxide, or aluminum oxide as a tracking resistance improver. A flame-retardant silicone composition having X-ray shielding ability, characterized by containing one or more of magnesium hydroxide and hydrotalcite.