JPS5930240B2 - Flame-retardant silicone composition with X-ray shielding ability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides silicone compositions that are flame retardant, have X-ray shielding ability, and have excellent anti-tracking properties, such as silicone rubber compounds, potting materials, festivals, adhesives, etc. The purpose is to provide the following.

More specifically, tungsten oxide is used as an X-ray shielding material in a silicon composition containing at least platinum or a platinum compound as a flame retardant.

Zinc oxide, zinc carbonate, titanium oxide, strontium titanate, lead titanate, zirconium oxide, lead zirconate,
Manganese dioxide, manganese carbonate, nickel oxide, 32
Nickel oxide, nickel carbonate.

cobalt oxide, cobalt 32 oxide, basic cobalt carbonate, niobium oxide, tantalum pentoxide, bismuth oxide,
Iron hydroxide, ferrous oxide, ferric oxide.

43 iron oxide, cuprous oxide, cupric oxide, indium oxide, tin oxide, and barium carbonate.

Furthermore, in cases where the anti-tracking property deteriorates due to the essential properties of the X-ray shielding material or trace impurity components, aluminum hydroxide, aluminum oxide, magnesium hydroxide.

Hydrotalcite (Mg I B At6 (OH)
At least 1 of 48(CO3)3・12H20)
By containing these, a silicone composition with extremely excellent anti-tracking properties can be obtained.

Furthermore, barium titanate is an X-ray shielding material.

It is also possible to additionally add barium fluoride or the like.

In recent years, silicone compositions have been widely used as glazes, compounds, potting materials, adhesives, adhesives, etc. due to their excellent electrical, mechanical, and various physical properties.

In that case, platinum or a platinum compound is added as a flame retardant to make the silicone composition flame retardant.

On the other hand, when used as an anode camp for a color television cathode ray tube, in addition to conventional flame retardant performance, X-ray shielding performance is required.

However, in the conventional flame-retardant silicone compositions as described above, the reality is that no one has yet been proposed that combines flame-retardant performance and X-ray shielding ability.

Generally, to impart X-ray shielding ability to various materials, it is sufficient to add a lead compound or a barium compound, but in the case of the above-mentioned flame-retardant silicon composition, its flame-retardant mechanism utilizes a catalytic action. When additives are added to the catalyst, it is extremely susceptible to catalyst poisoning (there is a problem that the flame retardant properties are immediately lost).

First, the flame retardant* mechanism in such a silicone composition will be explained.

As a general means of flame retardation, flame retardation can be achieved by adding a flame retardant such as those used in ordinary organic polymers, or by introducing logen groups into the polymer itself.

However, these have drawbacks such as generating toxic gas when burned, and are not used for making silicon compositions flame retardant.

Flame-retardant silicone compositions are made by adding a platinum compound, which originated from the technique disclosed in Japanese Patent Publication No. 44-2591, and is now used in most of the current flame-retardant silicone compositions. There is.

For example, it is said that the combustion mechanism of silicone rubber Q is that trimers and tetramers are produced by the reaction of , and the silicone rubber composition is thermally decomposed (possibly).

On the other hand, the method published in the above publication involves the reverse reaction of reaction formula (1), that is, the reaction in which the generated decomposed components are subjected to additional bonding again before becoming trimers or tetramers. The reaction (2) below, in which steric structure formation occurs, is significantly promoted by adding 3 to 250 ppm of a platinum compound.

This is effective when added in a small amount of about ppm, and is the only catalyst other than platinum compounds that has little effect on deterioration at around 180° C., where silicon compositions are normally used.

Currently, this method has been further developed and benzotria
Zol, azobisin butyronitrile.

Diazoaminobenzene, methylmethacrylonitrile,
Further flame retardancy is achieved by adding small amounts of organic compounds such as methylhydrodiene polysiloxane and metal oxides such as titanium oxide and nickel oxide.

Even in that case, the platinum catalyst still plays an important role.

However, in such flame retardant methods, although platinum catalysts exhibit great effects even in small amounts, they have the disadvantage that they are easily poisoned by certain small amounts of impurities.

For example, compounds such as N, P, S, Pb, Sn, HP
, Bi compounds are said to have a particularly large influence.

This is thought to be because these act as radical scavengers by inhibiting the reaction (2) above.

Therefore, the present invention provides a silicon composition made of platinum or a platinum compound that can effectively impart X-ray shielding ability while maintaining the flame retardant properties. , tungsten oxide (WO3
), zinc oxide (ZnO).

Zinc carbonate (Z n CO3) w Titanium oxide (T' t
02) t Strontium titanate (S rT
i03) tLead titanate (PbTi03), zirconium oxide (Zr02).

Lead zirconate (PbZrO3), manganese dioxide (Mn
O2) to manganese carbonate (MnC03), nickel monoxide (NiO2), nickel 32 oxide (Ni203)
).

Carbonic acid-'-7 Kel (NiCO3), cobalt monoxide (C
oO).

Cobalt 32 acid (CO203), basic cobalt carbonate (2CoCO3*3CO(OH)2), niobium oxide (Nb205) = 5 mental oxide (Ta205)
) to bismuth oxide (Bl 203 ) e iron hydroxide (F
e (OH) 2) - Ferrous oxide (FeO), ferric oxide (Fe 203 ) s43 iron oxide (Fe 304
) Cuprous oxide (Cu20) Cupric oxide (CuO
), indium oxide (In203) and tin oxide (Sn0
2) The silicon composition is characterized in that the silicon composition contains at least one of barium carbonate (BaCO3).

According to experiments conducted by the present inventors, these X-ray shielding materials do not have the above-mentioned catalyst poisoning effect on platinum and platinum compounds, and therefore have a small It has been confirmed that by adding at least one of these inorganic compounds to the composition, it is possible to obtain an excellent silicone composition that also has X-ray shielding ability without impairing flame retardant performance.

It is not yet clear why these compounds are non-toxic to the flame retardant action of platinum or platinum compounds.

The amount of calories added depends on the type and physical properties of the organopolysiloxane that is the base resin, the amount of other fillers, and the purpose.
The material is determined according to design requirements such as the required mechanical strength, the cost since additives are cheaper, the degree of X-ray shielding, and the thickness of the material.

The effect of attenuating X-rays due to the inclusion of the X-ray shielding agent in the present invention is expressed by the following equation, which corresponds to the Lambert-Beer law of light.

■ −-μX O However, Io: Intensity before passing through the material I: Intensity after passing through the material In reality, there are some differences between monochromatic X-rays and white X-rays.

That is, in the case of white X-rays, the value of μ is not constant, but there is a tendency for μ to decrease as X increases little by little.

Table 1 shows the IR absorption coefficient of each X-ray shielding material at each wavelength.

Even when each X-ray shielding compound is actually added to a silicon composition, its absorption coefficient is determined by the abundance of each atom therein, so it can be calculated based on Table 1.

In addition, when using a ferroelectric compound, the dielectric constant of the silicon composition can be adjusted by adjusting the amount added, so it is possible to adjust the dielectric constant of the silicon composition to meet the characteristics required for electronic and electrical components. A silicone composition can be obtained.

Further, the same X-ray shielding effect can be obtained by using these X-ray shielding compounds alone or in any combination.

Even in the case of materials with low absorption coefficients, high shielding effects can be obtained by increasing the amount added or by increasing the thickness of the design.

In addition, it goes without saying that the flame-retardant silicone composition according to the present invention is effective not only for X-ray shielding but also for other radiations depending on the type of material it contains. It is something.

The amount to be added is determined by the designed thickness of the material, required mechanical properties, electrical properties, required shielding properties, cost, etc.

Next, we will discuss improvements in tracking resistance.

As described above, by adding effective materials, X-ray shielding ability can be obtained without losing flame retardancy.

However, depending on the type, purity, and other factors of the additive material, the tracking resistance may be affected under high load conditions, such as 800v%L.
It may decrease in A.

The present invention also provides a composition that prevents this deterioration of tracking resistance properties, and includes aluminum hydroxide, aluminum oxide, magnesium hydroxide, hydrotalcite (Mg18At6(OH)48(C03)3.12
H20).

The amount to be added depends on the degree of X-ray shielding material, but a considerable effect can be obtained by adding about 2 to 4 parts by weight.

Of course, it can be more or less than this.

Examples of the present invention will be shown below.

Example 1 (CHa) 2 S i O units 99.9 moles, C
H3 (CH2= CH) 100 parts of organosiloxane raw rubber consisting of 0.1 mole of S i O units, and hume silica (Aerosil 200, Nippon Aerosil ■ 1) 1
5 parts, 2.5 parts of silica dispersant, and 15 parts of powdered manganese carbonate.
A mixture of 7 parts of anatase-type titanium oxide and 0.05 parts of a dichloroplatinic acid (in terms of platinum) butanol solution was uniformly mixed with two rolls, and this was treated at 150°C for 1 hour. This was used as a silicone rubber compound, which was used as the base resin of this example.

Next, a certain amount of the X-ray shielding material according to the present invention as shown in Table 2 was weighed out and added to the base resin.

Further, to these, 0.7 parts 7 of a silicone oil base containing 50 parts of benzoyl peroxide was added as a curing agent, and thoroughly kneaded with two rolls to prepare a sample.

These were heated at 120°C for 20 minutes under a pressure of 50~/crtl, and further heated at 150°C for 3 hours to prepare sample sheets, and a combustion test was conducted on these as shown in Table 2.

The combustion test was conducted in accordance with UL-94.

That is, on a sample piece 1/16" thick, 0.5" wide, and 5" long, a %" blue flame was emitted from the tip of a Bunsen burner using city gas, and this flame was applied to the sample for 10 seconds. ,
The burning time after the flame was removed (first flaming) was measured.

After the flame has extinguished, immediately apply the flame of a burner and take the same measurement.
(Second Flaming) and the duration of the red-hot state after extinguishing the inflammation (Second Blowing).

According to these results, it is clear that the X-ray shielding material according to the present invention does not act as a catalyst poison for the flame retardant mechanism of silicone rubber.

Example 2 A silicone rubber compound base range prepared in the same manner as in Example 1 was added with various X-ray shielding materials and aluminum hydroxide as a tracking resistance improver.

Aluminum oxide, magisium hydroxide, and hydrotalcite were added, and a test sheet was molded in the same manner as in Example 1, and a tracking resistance test was conducted at 800 V/A.

The test results * Seven fruits are shown in Table 3.

It should be noted that the anti-tracking improver according to the present invention does not have an adverse effect on the flame retardant mechanism of silicone rubber, either alone, in combination with each other, or in combination with an X-ray shielding material.

As a result of the above, it was confirmed that there is no catalyst poisoning effect on the flame retardant mechanism, which is the main objective of the present invention, and that the effect of improving tracking resistance properties is achieved.

The present invention can be applied not only to silicone rubber compounds but also to all silicone compositions that are made flame retardant using platinum catalysts, such as for ponting, electric wires, etc.
Various festivals and ceilings.

Adhesives and the like can be considered and can be used for a wide variety of purposes.

Claims (1)

[Claims] 1. A silicone composition containing a small amount of platinum or a platinum compound as a flame retardant, tungsten oxide, zinc oxide, zinc carbonate, titanium oxide, strontium titanate,
Lead titanate, zirconium oxide, lead zirconate, manganese dioxide, manganese carbonate, nickel monooxide, nickel 32 oxide, nickel carbonate, cobalt monoxide, cobalt 32 oxide, basic cobalt carbonate, niobium oxide, tantalum pentoxide, oxide Bismuth, iron hydroxide, ferrous oxide, ferric oxide, 43 iron oxide, cuprous oxide, cupric oxide. A flame-retardant silicon composition having X-ray shielding ability, characterized by containing at least one of indium oxide, tin oxide, and barium carbonate. 2. As a tracking resistance improver for silicone compositions,
Aluminum hydroxide, aluminum oxide. A flame-retardant silicone composition having an X-ray shielding ability as claimed in claim 1, which contains at least one of magnesium hydroxide and hydrotalcite.