KR100553725B1 - Silicone varnish composition for glass sleeve coating - Google Patents

Abstract

The present invention relates to a silicone varnish composition for coating glass fiber braided tubes, and more particularly, to organo polysiloxane resin, mixed silicone oil of vinyl polysiloxane and hydrogen polysiloxane, calcium carbonate, hydrophobic fumed silica, rare earth metal oxide and The present invention relates to a silicone varnish composition for coating a glass fiber braided tube by preparing a varnish composition by containing a platinum catalyst in a predetermined amount, and having excellent self-extinguishing, electrical insulation, flexibility and elasticity, and a fast curing rate.

Glass Fiber Braided Tube, Silicone Varnish, Self Extinguishing, Electrical Insulation

Description

Silicone varnish composition for glass fiber braided tube coating             

1 shows IR data of Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ), which is a platinum catalyst used in the present invention.

The present invention relates to a silicone varnish composition for coating glass fiber braided tubes, and more particularly, to organo polysiloxane resin, mixed silicone oil of vinyl polysiloxane and hydrogen polysiloxane, calcium carbonate, hydrophobic fumed silica, rare earth metal oxide and The present invention relates to a silicone varnish composition for coating a glass fiber braided tube by preparing a varnish composition by containing a platinum catalyst in a predetermined amount, and having excellent self-extinguishing, electrical insulation, flexibility and elasticity, and a fast curing rate.

Silicone varnishes have siloxane bonds and exhibit excellent properties in various aspects, including heat resistance, weather resistance and chemical stability. The material having a siloxane structure has a large bond energy, but unlike carbon-carbon bonds, it has a helical structure and has a small intermolecular force, which is rich in elasticity and has a high compressive force. Enhancer is added and used.

In general, silicone varnish is used as an additive in a special field of paint, but nowadays it is widely used as a coating material such as glass fiber braided tube and insulation coil because it shows an excellent effect on the flame retardant and electrical insulation properties. However, when used as a coating material for electrical and electronic, environmentally friendly cotton and fire safety requirements, including VOC regulations and ISO 14000, day by day requires more stringent test standards.

In addition, the silicone varnish composition having self-extinguishment does not exhibit sufficient self-extinguishing ability with only silicon, and inorganic metal compounds including platinum compounds [US Pat. No. 4,073,99, US Pat. No. 4,678,827]. Metal oxides [US Patent No. 4087399, US Patent No. 4110300, US Patent No. 5543450], Silica [US Patent No. 4678827, US Patent No. 5919298], Carbon Black [US Patent No. 4087399, USA Patent No. 5059648], Amines [US Patent No. 42,2917, US Patent No. 4486567, US Patent No. 4678827], Acid Anhydrides [US Patent No. 4486567, US Patent No. 5516832], Azo Compounds [US Patent No. 4087399] No. 5543450] and quartz powder [US Pat. No. 58,824,673] have been used, which increases the price of silicon varnishes and is harmful to humans and emits environmentally friendly inhibitors. It was good.

Therefore, in order to reduce the amount of the compound used, low-cost flame retardants and extenders and harmless and environmentally friendly flame retardants and insulation additives were used together, but they did not show satisfactory effects in terms of self-extinguishing and battery insulation. These examples illustrate the improper use of platinum compounds, including platinum, and extenders. It did not exhibit the satisfactory self-extinguishing properties required for electronics [ツ リ コ-ソ 活用 技術-情報 技術 協會]. In addition, when the silica, the extender and other additives are used together, the uncured compound of the coating film is more severely cracked over time, resulting in a decrease in electrical insulation and poor appearance [ツ リ コ-ソの 應用-東京 芝 浦 電氣-ツ リ コ-ソ (株), 1988]. In addition, when azo compounds and amines are used, yellowing occurs and high odor occurs under high temperature conditions [Silicone Additives-Dowcorning Korea. Co. Ltd, ツ リ コ-ソ の 最新 應用 技術 -CMC ツ-エ ム ツ-, 1982]. In addition, when the metal oxide and the quartz powder are used together, the flame retardant effect and the electric insulation are excellent, but the adhesion of the coating film and the flexibility and the elasticity of the coated substrate are reduced. [US Patent No. 5882467, 2001 New Technology Trend Report-Polymer Additives, Patent Office]

Accordingly, the present inventors have endeavored to solve the above problems, and as a result, the organopolysiloxane resin, a mixed silicone oil of vinyl polysiloxane and hydrogen polysiloxane, calcium carbonate, hydrophobic fumed silica, rare earth metal oxide and platinum catalyst are fixed. When the varnish composition was prepared by the content, it was found that the silicone varnish composition having improved self-extinguishing and electrical insulation was completed.

Accordingly, an object of the present invention is to provide a silicone varnish composition having excellent self-extinguishing properties and electrical insulation, as well as flexibility and elasticity, a fast curing speed, and low temperature curing.

The present invention provides a silicone varnish composition containing a conventional additive containing a silicone resin, a silicone oil and an inorganic metal compound,

As said silicone resin, (1) 4-7 weight% of organo polysiloxane resin;

The silicone oil may be (2) 65 to 75% by weight of a mixture of vinyl group polysiloxane and hydrogen polysiloxane; and

As a conventional additive containing the inorganic metal compound

(3) 5 to 20% by weight of calcium carbonate, (4) 3 to 10% by weight of hydrophobic fumed silica, (5) 1 to 5% by weight of rare earth metal oxides, and (6) 0.5 to 10% by weight of platinum catalyst. Silicone varnish compositions have their characteristics.

Hereinafter, the present invention will be described in more detail.

Looking at the components constituting the silicone varnish composition of the present invention are as follows.

(1) organopolysiloxane resin

Organopolysiloxane resin is a kind of silicone resin, which is a polymer of M unit and Q unit, represented by the following structural formula, and acts as a crosslinker for bonding silicone oil and silica to each other. It is dispersed and mainly related to physical properties such as adhesion, flexibility and elasticity.

[constitutional formula]

The organo polysiloxane resin is also referred to as 'MQ resin', and refers to a polymer polymer composed of M units of R ₃ SiO _1/2 and Q units of SiO _4/2 , wherein R is a functional or nonfunctional organic compound. Group. The resin may also contain a portion of R ₂ SiO _2/2 and R ₁ SiO _3/2 units, referred to as D and T units, and in the present invention include 1 to 20 mole% D and T units of the resin molecule. It is used to, it is advantageous to improve the flexibility and elasticity in the above range.

In general, the characteristics of the silicone resin mainly consists of the number average molecular weight of the resin, the ratio of the M unit and Q unit, the reactor content of the D and T unit of the silicone resin, and the number average molecular weight of the MQ resin used in the present invention. Silver 1,000-10,000, Preferably it is 3,000-7,000, More preferably, it is good to use 3,500-6,500. When the number average molecular weight is less than 1,000, a phenomenon that the coating film is broken occurs, and when the number average molecular weight is more than 10,000, the coating film becomes sticky. In addition, the Q unit: M unit is 1: 0.5 to 1.3, preferably 1: 0.5 to 1.1, more preferably 1: 0.5 to 1.0 molar ratio is preferably used mixed, if the above range is less than 0.5 coating coating film When the adhesive strength of is lowered and exceeds 1.3, cracks are generated on the surface of the coating film.

The organopolysiloxane resin is used in 4 to 7% by weight, the amount of use is less than 4% by weight of the coating film is weak, when the content exceeds 7% by weight cracking occurs in the coating film.

(2) silicone oil

Silicone oils serve as the main binders for silicone varnishes and include higher cycloaliphatic and non-cycloaliphatic (ie linear or branched aliphatic) epoxy polysiloxanes, polysiloxanes containing halogen atoms or cyano groups, and phenyl or alkenyl. Organosiloxane containing a hydrocarbon radical, etc. to contain are used.

In this invention, vinyl group polysiloxane and hydrogen polysiloxane are mixed and used, The mixing ratio of the vinyl group and hydrogen group in the said polysiloxane is good to mix in 1: 1.5-3.0 molar ratio. That is, by using the hydrogen group in excess of the vinyl group it can promote the crosslinking of the two working periods to promote the curing rate. When the hydrogen group mixing ratio of the polysiloxane is less than 1.5, uncured reactants are generated and harden well. When the hydrogen group is more than 3.0, hydrogen gas is generated by mutual reaction of the hydrogen groups to pass through the coating film, resulting in poor appearance of the coating. Done.

Examples of the vinyl group polysiloxane include methylvinyl polysiloxane, dimethyl polysiloxane, fluoromethylvinyl polysiloxane, methylfluoroalkyl polysiloxane, phenylvinyl polysiloxane, and the like, and generally have a molecular weight (Mn) of 10 to 700,000, preferably Is 10 to 500,000, more preferably 10 to 300,000, and a viscosity of 100 to 100,000 cps can be used. Such vinyl-based polysiloxanes are used differently depending on their use, and methylphenylvinyl polysiloxane, oil-resistant methylfluoroalkyl polysiloxane, etc. may be used for heat resistance and cold resistance.

Hydrogen polysiloxanes can also be used, for example, methylhydrogen polysiloxanes, polysiloxanes end-capped with hydrogen, copolymerized methylhydrogen polysiloxanes, etc., which are formed as methylene bonds under platinum compounds. The molecular weight (Mn) of the hydrogen polysiloxane is 10 to 500,000, preferably 10 to 300,000, more preferably 10 to 200,000, and a viscosity of 10 to 1,000 cps may be used.

The silicone oil is used from 65 to 75% by weight, and if the amount is less than 65% by weight, cracking occurs in the coating film, and when it exceeds 75% by weight, the flexibility and resilience of the coating film is reduced.

The present invention uses calcium carbonate, hydrophobic fumed silica, rare earth metal oxide and platinum catalyst as additives to impart self-extinguishing together with the silicone resin and silicone oil components.

(3) calcium carbonate

Calcium carbonate acts as an extender and flame retardant, and at the same time, carbon dioxide gas is generated during combustion to dilute the combustible gas. The calcium carbonate has a particle size of 10 to 30 ㎛, pH of 8.5 to 9.5 to prevent the mechanical properties of the coated coating film is lowered.

It is preferable to use 5 to 20% by weight of the calcium carbonate, preferably 5 to 15% by weight. If the amount is less than 5% by weight, it is difficult to express the flame retardant effect, and when the amount exceeds 20% by weight, the specific gravity becomes too high.

(4) hydrophobic fumed silica

The hydrophobic fumed silica is surface treated with an organosilane, an organosiloxane, an organosilazane, and an organosilicon compound, and then subjected to a surface treatment with a titaniumate compound, and more preferably, the fumed silica treated with the surface is treated with titaniumate. The surface can be retreated with a compound. The hydrophobic fumed silica has a particle size of 8 to 16 µm and a specific surface area (BET method) of 200 to 400 m ² / g. In this case, it is easy to disperse, thereby reinforcing the flexibility and elasticity of the coating film. do.

The hydrophobic fumed silica is used in an amount of 3 to 10% by weight, preferably 3 to 7% by weight. When the amount is less than 3% by weight, the hardness decreases, and when it exceeds 10% by weight, cracks occur in the cured coating film. do.

(5) Rare Earth Octoate (REO)

Rare earth metals belong to the Group 3 a subgroup of the chemical periodic table, including 15 elements from atomic number 57 La to 71 Lu and 17 elements including Sc and Y. Such rare earth metals are not as rare as their names, and by Clark's number, Ce has the most Ce in the rare earth than Sn. Rare earth metals generally have +3 valences and very similar ionic radii, so their chemical properties are very similar, so the separation of rare earth metals is very difficult. Rare earth metals are used in the form of metal compounds and metal oxides, and the metal compounds are mainly used for catalysts and metal oxides for inorganic materials and phosphors.

In the present invention, a mixture of a rare earth metal oxide mixture and an organic acid is used. Preferably, a mixture of 67 to 77 wt% of a rare earth metal oxide and 23 to 33 wt% of 2-ethylhexanoic acid is used. The rare earth metal oxide mixture is Y ₂ O ₃ , LaO ₃ , CeO ₂ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ And Lu ₂ O ₃ It can be used selected from

Rare earth metal oxide is an excellent raw material for improving self-extinguishing and heat resistance, but when used alone, it is preferable to use it as a minimum amount of mixture for increasing the dispersing power because the dispersing power is weak and causes cracking in the coating film.

The rare earth metal oxide is used in an amount of 1 to 5% by weight, preferably 1 to 3% by weight, and when the usage amount is out of the range, a problem arises in that the appearance of the coating film such as staining occurs in the coating film.

(6) Platinum Catalyst

Platinum catalysts are commonly used as curing accelerators, and the effects of the flame retardant, heat resistance, and electrical insulation are very excellent.

In the present invention, (ethylene) bis (triphenylphosphine) platinum (Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ )) is synthesized with a platinum catalyst, and its self-extinguishing ability is made effective by making its dispersion force uniform. The synthesized platinum catalyst is dispersed and used in isopropyl alcohol to give. The platinum catalyst improves self-extinguishing property and excellent compatibility with silicone oil, so that it is well dispersed in the silicone oil. Thus, the platinum catalyst not only enhances the curing rate but also does not separate the silicone oil and improves storage stability.

In the present invention, the synthesized platinum catalyst (ethylene) bis (triphenylphosphine) platinum (Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ )) alone or using the following phosphate-based platinum One or more types can be selected and used out of a compound. Examples of phosphoric acid-based platinum compounds include Pt {P (OC ₆ H ₅ ) ₃ } ₄ , Pt {P (C ₆ H ₅ ) ₃ } ₄ , Pt {P (CH ₃ ) ₃ } ₄ , Pt {P (C ₄ H ₉ ) ₃ } ₄ , Pt {P (OCH ₃ ) ₃ } ₄ , Pt {P (OC ₆ H ₅ ) ₃ } ₄ , Pt {P (C ₆ H ₅ ) ₃ } ₃ , Pt {P (C ₆ H ₅ ) (C ₂ H ₅ ) ₂ } ₄ , Pt {P (OC ₆ H ₅ ) (OC ₂ H ₅ ) ₂ } ₄ , Pt {P (C ₆ H ₅ ) ₂ (OC ₂ H ₅ )} ₄ And Pt {P (CH ₃ ) ₂ (OC ₄ H ₉ )} ₄ .

The platinum catalyst is preferably 0.5 to 10% by weight, preferably 0.5 to 5% by weight. When using a large amount exceeding the above range, the silicone varnish has excellent curability, self-extinguishing property, electrical insulation, etc. Due to the rapid curing rate, bubbles may be formed in the coating film, and the appearance may not be beautiful, and black spots may appear in the coating film due to oxidation of the platinum catalyst itself.

The platinum catalyst synthesized in the present invention was prepared by preparing Pt {P (C ₆ H ₅ ) ₃ } ₂ (CO ₃ ) as a precursor and then synthesizing it using the precursor, and the synthesis thereof will be described in detail below. .

Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) Synthesis

_{Pt {P (C 6 H 5} ) 3} 2 (C 2 H 4) as a precursor for the synthesis of _{Pt {P (C 6 H 5} ) 3} 2 it was synthesized (CO _3). 5 g (4 mmol) of Pt {P (C ₆ H ₅ ) ₃ } ₄ was dissolved in 120 mL of benzene, and the dissolved solution was bubbled with CO ₂ and O ₂ gas for about 30 minutes. The mixture is very dark yellow. The solid was filtered using a medium pore filter, which was washed with 50 mL of benzene, dissolved in 75 mL of dichloromethane, and 5 g (19 mmol) of triphenylphosphine was added thereto. The mixture was refluxed for at least 12 hours and 75 mL of benzene was added and then evaporated until the total volume was halved. After filtration using a medium pore filter, a solid was obtained, washed with 50 mL of benzene and 25 mL of ethanol, and then the washing solution was evaporated to obtain a precursor.

In a 100 mL Two-neck flask, 1.5 g (1.75 mmol) of Pt {P (C ₆ H ₅ ) ₃ } ₂ (CO ₃ ) was dissolved in 40 mL ethanol, and a dropping funnel was fixed to one neck. On the other side, the tube was connected so that ethylene gas could reach the surface of the mixture. 20 mL of 0.1M sodium tetrahydroborate (NaBH ₄ / Ethanol) was added to the dropping funnel and added dropwise over 20 minutes with vigorous stirring. At this time, ethylene gas was continuously injected. After filtration through a medium pore size filter, a solid was obtained, washed in the order of 20 mL of ethanol, 25 mL of H ₂ O and 25 mL of ethanol, evaporated and dried in vacuo to give a pale yellow Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) was obtained. IR data of Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) obtained above is shown in FIG. 1 (yield: 70%)

The present invention includes a silicone varnish obtained by curing a composition composed of the above components.

The silicone varnish according to the present invention as described above is useful in electric and electronic fields because it excludes the conventional flame retardant material, improves self-extinguishing and electrical insulation, and has excellent flexibility and elasticity, fast curing speed, and low temperature curing. Can be.

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

 Examples 1-3 and Comparative Examples 1-3

The components and contents of the silicone resins, silicone oils, calcium carbonates, hydrophobic fumed silica, and rare earth metal oxides of Examples 1 to 3 and Comparative Examples 1 to 3 shown in the following Table 1 were separately added, dispersed, and Curing compound (PART-A) was prepared.

Platinum catalyst (PARTB) was added to the uncured compound (PART-A) prepared above to be sufficiently dispersed, and then pressurized for 100 minutes at a pressure of 100 kgf / cm ² , 170 ° C. in a molding die through a degassing process, and thickness 1 A sheet of mm was formed. The sheet thus formed was left in a constant temperature and humidity chamber at 25 ° C. and 50% relative humidity for 24 hours, and then dried in a hot air drying circulation oven at 50 ° C. for 1 hour. At this time, the moisture on the surface of the sheet should be completely removed to prevent the occurrence of flame retardant degeneration.

The physical properties of the sheet prepared by the above process were measured in the following manner, and the results are shown in Table 1 below.

Classification (% by weight) Example Comparative example One 2 3 One 2 3 Silicone Resin ¹⁾ 5 5 5 5 5 5 Silicone oil Methylvinylpolysiloxane ²⁾ 66 66 66 66 66 66 Methylhydrogen copolymerized polysiloxane ³⁾ 4 3 3 4 3 3 Calcium carbonate 15 15 15 15 15 15 Hydrophobic Fumed Silica 7 7 7 7 7 7 Rare earth metal oxides                                              One One One One One One Platinum catalyst A ⁴⁾ - - 1.5 - - - B ⁵⁾ 2 3 1.5 - - - C ⁶⁾ - - - 2 3 - D ⁷⁾ - - - - - 3 1): M: Q 0.8: 1 molar ratio, Mn 5,000 2): viscosity 10,000 cps, molecular weight 250,000, vinyl group content: 1.5 mol% 3): viscosity 50 cps, molecular weight 250,000, hydrogen group content: 3.3 mol% 4): Pt {P (C ₆ H ₅ ) ₃ } ₄ 5): Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) 6): Pt {P (OC ₆ H ₅ ) ₃ } ₄ 7) : Pt {P (OC ₆ H ₅ ) (OC ₂ H ₅ ) ₂ } ₄

[Measurement of physical properties]

1. Self-extinguishing

1) Measure the time to extinguish each specimen by burning it for 10 seconds in a methane flame. The flame of the specimen is extinguished and the flame is burned again for 10 seconds and the measured combustion time value is added.

2) The measured data values in [Table 2] represent the average value of 5 specimens in a bundle.

3) Specimen condition and size were to comply with UL94V-0 vertical combustion test specification as stated above, and 1 mm thick specimen was used.

2. Mechanical Properties: Elasticity, Resilience

1) The specimens were prepared to the same specifications as the specimens used in the self-extinguishing test, and the stretching degree of the specimens was measured by a tensile tear tester (Shimadzu Co., Ltd.) according to JIS K6249 standard.

3. Flexibility

1) The two ends of the specimens prepared by immersion coating the glass fiber braided tube on the silicone varnish were tested by 180 ° to recover the original form.

2) The coating thicknesses of the coated specimens were all 0.5 mm, and were measured with a silicon coating meter (X-LAB 3000, OXFORD).

4. Electrical insulation

1) The dielectric breakdown strength and the volume resistivity were tested with silicon specimens made from 100 × 100 × 1 mm plates.

2) In order to prevent flashover, the dielectric breakdown strength was placed between the spherical electrodes in water and subjected to the dielectric breakdown by a short breakdown test method in order to prevent flashover.

3) The volume resistivity was in compliance with ASTM D257 test standard, and the gap size of the guard electrode was measured as 1.0 mm.

4) The measuring instrument used a High Resistance Meter ((Hewlett Packard 4329A).

5. Curing rate and curing temperature

1) The curing rate and curing temperature of the silicone varnish coated on the glass fiber braided tube were measured in an oven.

division Example Comparative example One 2 3 One 2 3 Self-extinguishing (sec) 4 3 3 Complete combustion 118 122 Mechanical properties elasticity (%) 630 685 615 220 230 215 Resiliency (%) 98 98 98 21 34 45 flexibility Good Good Good Bad Bad Bad Electrical insulation Insulation breakdown strength (KV / mm) 21 24 23 10 11 13 Volume resistivity (10 ¹⁵ Ω㎝) 18 19 18 One 3 2 Cure Speed (sec) 15 14 15 32 36 30 Curing temperature (℃) 77 75 78 120 115 112

As shown in Table 2, the sheet prepared using the silicone varnish composition according to the present invention was excellent in self-extinguishing, electrical insulation, flexibility, resilience and elasticity, it was confirmed that the curing speed is fast and low temperature curing is possible.

As described above, the silicone varnish composition according to the present invention, unlike the conventional platinum catalyst (ethylene) bis (triphenylphosphine) platinum (Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) ), It is very useful for electric and electronic fields because it has the excellent effect of self-extinguishing and electrical insulation, as well as elasticity, flexibility and resilience.

Claims (4)

In a silicone varnish composition containing a conventional additive containing a silicone resin, a silicone oil and an inorganic metal compound, As said silicone resin, (1) 4-7 weight% of organo polysiloxane resin; The silicone oil may be (2) 65 to 75% by weight of a mixture of vinyl group polysiloxane and hydrogen polysiloxane; and As a conventional additive containing the inorganic metal compound (3) 5 to 20% by weight of calcium carbonate, (4) 3 to 10% by weight of hydrophobic fumed silica, (5) 1 to 5% by weight of rare earth metal oxides, and (6) 0.5 to 10% by weight of platinum catalyst. Silicone varnish composition, characterized in that. The silicone varnish composition according to claim 1, wherein the silicone resin is an organopolysiloxane resin having a Q unit: M unit of 1: 0.5 to 1.3 molar ratio represented by the following structural formula 1 and a number average molecular weight of 1,000 to 10,000. . [Formula 1]

In the above formula 1, R represents a functional or non-functional organic group. The silicone varnish composition according to claim 1, wherein the silicone oil is a mixture of vinyl group and hydrogen group in vinyl polysiloxane and hydrogen polysiloxane in a 1: 1.5 to 3.0 molar ratio. The method of claim 1, wherein the platinum catalyst is Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) alone or Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) and Pt {P (OC ₆ H ₅ ) ₃ } ₄ , Pt {P (C ₆ H ₅ ) ₃ } ₄ , Pt {P (CH ₃ ) ₃ } ₄ , Pt {P (C ₄ H ₉ ) ₃ } ₄ , Pt {P (OCH ₃ ) ₃ } ₄ , Pt {P (OC ₆ H ₅ ) ₃ } ₄ , Pt {P (C ₆ H ₅ ) ₃ } ₃ , Pt {P (C ₆ H ₅ ) ₃ } ₂ (C ₂ H ₄ ) _, Pt {P (OC ₆ H ₅ ) (OC ₂ H ₅ ) ₂ } ₄ , Pt {P (C ₆ H ₅ ) ₂ (OC ₂ H ₅ )} ₄ and Pt {P (CH ₃ ) ₂ (OC ₄ H ₉ )} _{4. The} silicone varnish composition comprising using one or more selected from _four .

Images