KR940010970B1 - Organopolysiloxane Liquid Injection Molding Composition - Google Patents

Abstract

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Description

Organopolysiloxane Liquid Injection Molding Composition

The present invention relates to translucent high strength organopolysiloxane liquid injection molding compositions. More particularly, the present invention relates to compositions cured through SiH addition reactions with controlled mixtures of olefin containing organopolysiloxanes.

Liquid injection moldable (LIM) organopolysiloxane compositions are known and used. The problem with all these compositions is that the hardness, tensile strength, elongation and tear strength are so interdependent with the viscosity of the liquids themselves and not cured that it is difficult to improve one property without losing other properties. In particular, it is desired to improve the hardness and tear strength without losing other properties.

US Pat. Nos. 3,884,866 and 3,957,713 to Jeram describe high strength addition cured compositions suitable for low pressure liquid injection molding. These compositions comprise a first component containing a high viscosity vinyl end-terminated organopolysiloxane, a low viscosity vinyl containing organopolysiloxane, a filler and a platinum catalyst, which are cured by mixing with a second component containing a hydrogen silicon composition. do. The durometer (20 to 35 Shore A) of this composition is low and, moreover, it is difficult to increase the durometer or hardness without adversely affecting other properties.

US Pat. No. 4,162,243 to Lee et al. Describes a composition similar to the composition of Jeram, containing fumed silica treated with hexamethyldisilazane and tetramethyldivinyldisilazane as the most important features. In addition to the low viscosity in the uncured state, the composition such as Lee is cured into a high hardness elastomer while maintaining other properties including strength, elongation and tear strength.

Sweet, U.S. Patent No. 4,427,801, is an extension of Lee et al.'S patent by introducing MM ^Vl Q resins in addition to fumed silica treated with vinyl. This patent creates elastomers with high hardness and high tear strength, but with the disadvantages of high compression set and low Basoral resilience.

It is an object of the present invention to prepare a liquid injection molded organopolysiloxane composition having high hardness and high tear strength without adversely affecting other physical properties.

It is another object of the present invention to further prepare a liquid injection molded organopolysiloxane composition having excellent storage stability and releasability.

These and other objects will be apparent to those of ordinary skill in the art upon reading the specification, examples, and claims.

According to the present invention there is provided a LIM organopolysiloxane composition, comprising low viscosity, high strength and good elongation, with excellent hardness and tear strength, comprising:

(A) 70 to 98 parts by weight of a linear high viscosity vinyl end-terminated organopolysiloxane containing at most 25 mole percent (1) phenyl radical at 25 ° C. and having a viscosity of about 2,000 to about 1,000,000 cP, (2) one per molecule Linear low viscosity organopolysiloxane 1 to 15 weights having at least a terminal vinyl group, having a vinyl content of 0.01 mol% to 60 mol%, a viscosity of about 50 to about 5,000 cP at 25 ° C., and containing not more than 25 mol% of phenyl radicals. And (3) chain vinyl group-containing organopolysiloxane 1 to 15 having a vinyl content of about -0.1 to 25 mol%, a viscosity of about 50 to about 100,000cp at 25 ° C, and containing up to about 25 mol% of phenyl radicals. 100 parts by weight of a vinyl-containing organopolysiloxane component composed of parts by weight; (B) about 5 to about 70 parts by weight of a filler or a blend of fillers; (C) about 0.1 to 50 parts of a platinum catalyst per million parts of total organopolysiloxane composition; (D) about 0.5 to 25 parts by weight of a SiH composition selected from the group consisting of hydrogen-containing silane and hydrogen-containing organopolysiloxane; And (E) optionally from about 0.1 to 6.0 parts by weight of a hydroxy-containing organopolysiloxane fluid having a viscosity of about 5 to 100 cP at 25 ° C.

The composition may be cured with an elastomer for 16 hours at room temperature or for 10 seconds at elevated temperature, for example at 200 ° C. In a preferred embodiment, the composition is a two-component composition in which the first component contains all of at least component (C) and the second component contains at least both component (D).

The linear high viscosity vinyl end-terminated organopolysiloxane A (1) of the present invention contains up to 25 mole percent phenyl radical and has a viscosity of about 2,000 to 1,000,000 cP, preferably about 10,000 to about 500,000 cP at 25 ° C. These high viscosity organopolysiloxanes can be represented by General formula (1).

Wherein Vi is vinyl and R is selected from the group consisting of monovalent hydrocarbon radicals having up to about 20 carbon atoms and halogenated monovalent hydrocarbon radicals, x may be from about 100 to about 10,000, preferably from 500 to 2,000. Suitable high viscosity organopolysiloxanes are described in US Pat. No. 3,884,866, which is incorporated herein by reference.

The linear low viscosity organopolysiloxane A (2) of the present invention contains one or more terminal vinyl groups per molecule, the vinyl content may vary in the range of about 0.01 to about 60 mole percent, preferably 0.05 to 10 mole percent, At 25 ° C., the viscosity is from about 50 to about 5,000 cP, preferably from about 50 to about 1,000 cP; It contains up to about 25 mole percent phenyl radicals. These low viscosity organopolysiloxanes can be represented by General formula (2);

Wherein R is as defined above and R ¹ is the same as R, provided that at least one R ¹ must be vinyl and y can be from about 1 to about 750. Suitable low viscosity organopolysiloxanes are described in US Pat. No. 3,884,866, which is incorporated herein by reference.

The chain vinyl group-containing organopolysiloxane A (3) of the present invention is important for obtaining desirable properties. Suitable chain vinyl group-containing organopolysiloxanes have a vinyl content of about 0.1 to about 25 mole percent, preferably about 0.2 to about 5 mole percent, and a viscosity at 25 ° C. of about 50 to about 100,000 cP, preferably about 100 to It is about 10,000 cP and contains up to about 25 mole percent phenyl radicals. These organopolysiloxanes can be characterized as a copolymer of the siloxane unit (I) of the general formula (3) and the organosiloxane unit (II) of the general formula (4);

R _a R ² _b SiO _{(4-ab) / 2} (3)

R _c SiO _{(4-c) / 2} (4)

Wherein R is as defined above and R ² is an olefinic hydrocarbon radical attached to silicon by a C-Si bond, and generally contains 1 to 20 linear or branched aliphatic carbons, preferably multiple bonds. Contains 1 to 12 carbon atoms bonded by, a has a value of 0 to 2; The sum of a and b is 0.8 to 3.0 and c has a value of 0.8 to 2.5.

R ² may be, for example, allyl, metalyl, butenyl, pentenyl, ethenyl, etc., but is preferably vinyl. Generally, the copolymer contains 0.5 to 99.5 mol% of units of the general formula (3) and 0.5 to 99.5 mol% of the units of the general formula (4). Methods of making these copolymers are known in the art. These methods are described in Chalk, U.S. Patent No. 3,344,111 to Modic, U.S. Patent No. 3,436,366, which is incorporated herein by reference.

Preferred chain vinyl group-containing organopolysiloxanes are linear and have the general formula (5):

Wherein R and R ² are as defined above and d and e are positive integers such that the polymer contains up to about 20 mol% R ² .

Preferably, R ² is vinyl, the polymer contains from about 0.05 to 10 mole percent of R ² and the viscosity is in the range of from about 300 to about 1,000 cP at 25 ° C.

As mentioned above, R can be selected from the group consisting of monovalent hydrocarbon radicals of up to about 20 carbon atoms and halogenated monovalent hydrocarbon radicals, ie radicals typically associated as substituent groups for organopolysiloxanes. Thus, radicals R include mononuclear and binuclear aryl radicals such as phenyl, tolyl, xylyl, naphthyl and the like; Halogenated mononuclear and binuclear aryl radicals such as chlorophenyl, chloronaphthyl and the like; Mononuclear aryl lower alkyl radicals having 1 to 8 carbon atoms per alkyl group, such as benzyl, phenyl, etc .; Lower alkyl radicals having 1 to 8 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl and the like; Lower alkenyl radicals having 2 to 8 carbon atoms such as vinyl, allyl and 1-propenyl; Halo lower alkyl radicals having 1 to 8 carbon atoms such as chloropropyl and trifluoropropyl; And cycloalkyl radicals such as cyclobutyl, cyclopentyl and cyclohexyl. Although R may be any of those described above, one of ordinary skill in the art will readily recognize that R cannot be a high molecular weight radical and that R should not be selected to adversely affect vinyl group reactions. . Preferably, R is a lower alkyl radical having 1 to 8 carbon atoms, such as methyl and ethyl, phenyl and trifluoropropyl. More particularly, R is at least about 70 number percent methyl.

The nature of the invention and in particular the method of distinguishing the invention from the SiHolefin addition silicon rubber compositions of the prior art lies in the presence of three vinyl-containing organopolysiloxane compositions. As mentioned above, these vinyl-containing organopolysiloxanes include high viscosity organopolysiloxane A (1); Low viscosity organopolysiloxane A (2); And linear vinyl group-containing organopolysiloxane A (3). For each 100 parts by weight of the vinyl-containing organopolysiloxane, about 70 to 98 parts by weight of A (1), about 1 to 15 parts by weight of A (2), and about 1 to 15 parts by weight of A (3) should be present. More preferably, about 80 to 95 parts by weight of A (1), about 3 to 10 parts by weight of A (2), and about 3 to 10 parts by weight of A (3) should be present. These mixtures of vinyl-containing organopolysiloxanes result in cured compositions that are excellent in strength and elongation and at the same time excellent in hardness and tear strength. The cured composition has a tensile strength of at least about 1,000 psi, an elongation of at least 600%, a tear strength of at least 200 lb / in, and a Shore A hardness of at least 35-40.

The SiH composition (D) of the present invention acts as a crosslinking agent and may be selected from the group consisting of hydrogen-containing silanes and hydrogen-containing organopolysiloxanes. Hydrogen-containing organopolysiloxanes are preferred. Thus, the hydrogen-containing organopolysiloxanes of the present invention may be characterized as copolymers containing one or more units having formula (6) per molecule.

R _f H _g SiO _{(4-fh) / 2} (6)

Wherein the remaining siloxane units in the organopolysiloxane fall within the range of Formula (4), provided that R as well as R in Formula (4) must be saturated; f has a value of 0 to 2; The sum of f and g is 0.8 to 3.0. The viscosity of the hydrogen-containing organopolysiloxane should be about 5 to about 1,000 cP at 25 ° C., preferably about 5 to about 100 cP.

For example, MQ resins having H (R) ₂ SiO _1/2 and SiO ₂ units are included in the hydrogen-containing organopolysiloxanes described above. Moreover, resins, such as MDQ, MTQ, MDT, etc. which have a hydrogen substituent are included here. This copolymer generally contains 0.5 to 99.5 mol% of units of formula (6) and 0.5 to 99.5 mol% of units of formula (4).

Preferred hydrogen-containing organopolysiloxanes are linear organopolysiloxane polymers of the general formula (7):

Wherein R is as defined above except for the unsaturated compound, R ³ is the same as R except for the addition of the unsaturated compound and hydrogen, h is 1 to 1,000 and i is 5 to 200. More preferably, h is 10 to 500 and i is 5 to 200.

The hydrogen-containing organopolysiloxane (D) is used at a concentration of about 0.5 to 25 parts by weight per 100 parts by weight of (A), preferably at a concentration of about 0.5 to 10 parts by weight per 100 parts by weight of (A). In SiH materials, it is preferred that there is at least one hydrogen atom for each vinyl group in (A), preferably about 1.5 to about 2.5 hydrogen atoms for each vinyl group.

Many kinds of platinum catalysts for such SiH oliphen addition reactions are known, and such platinum catalysts can also be used for the reaction of the present invention. Preferred platinum catalysts where optical transparency is required are platinum compound catalysts which are soluble in the present reaction mixture. The platinum compound may be selected from those having the general formula (PtCl ₂ olefins) ₂ and H (PtCl ₃ olefins) as described in Ashby, US Pat. No. 3,159,601. The olefins represented by the preceding two general formulas can be almost any type of olefin, but are preferably alkenylene having 2 to 8 carbon atoms, cycloalkenylene or styrene having 5 to 7 carbon atoms. Specific olefins available in the above general formula are various isomers such as ethylene and propylene and butylene, cyclopentene, cyclohexene, cycloheptene and the like.

Further platinum containing materials useful in the compositions of the present invention are the platinum chloride cyclopropane complexes (PtCl ₂ C ₃ H ₆ ) described in Ashby, US Pat. No. 3,159,662.

The platinum-containing material is also produced from chloroplatinic acid with up to 2 moles of a compound selected from the group consisting of alcohols, ethers, aldehydes and mixtures thereof per gram of platinum as described in Lamoreaux, US Pat. No. 3,220,972. It may be a complex.

All patents and patent applications mentioned in this specification are incorporated herein by reference.

Preferred platinum compounds which are used not only as platinum catalysts but also as flame retardant additives are those compounds described in Karstedt's French Patent No. 1,548,775. Generally, platinum complexes of this type are produced by reacting chloroplatinic acid with 4 moles of water for hydration with tetravinylcyclotetrasiloxane in the presence of sodium bicarbonate in ethanol solution.

One skilled in the art can readily determine the effective amount of platinum catalyst. Generally, the effective amount is about 0.1 to 50 parts per million parts by total organopolysiloxane composition.

In order to obtain a high tensile strength in the composition of the present invention, particularly when the composition is formed into a thin film coating or film, it is preferable to incorporate the filler (B) into the composition. Examples of various fillers that can be used include titanium dioxide, lithopone, zinc oxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, calcium carbonate, fumed silica, silazane treated silica, precipitated silica, glass fibers, magnesium oxide, chromium oxide , Zirconium oxide, aluminum oxide, alpha quartz, calcined clay, asbestos, carbon, graphite, cork, cotton, synthetic fibers and the like.

Preferred fillers to be used in the compositions of the present invention are surface treated fumed silica or precipitated silica. As one of the surface treatment methods, fumed silica or precipitated silica is exposed to cyclic organopolysiloxane under pressure and heating. This surface treatment method is described in US Pat. No. 2,938,009 to Lucas, which is incorporated herein by reference. Another method for surface treatment of fillers is to expose silica to siloxane or silane in the presence of an amine compound. This method is described in US Pat. No. 3,024,126, which is incorporated herein by reference.

A preferred method of surface treatment of fillers is to use methyl silane or silazane surface treatment agents. Methylsilane or silazane surface treated fumigation or precipitated silica fillers do not undesirably increase the low viscosity of the composition that flows easily and does not cure. At the same time, however, the silazane treated silica filler increases the physical properties of the cured elastomer, in particular the tear strength. The best properties are obtained when the silazane treatment for the filler is carried out in situ, ie when the filler is mixed with the composition (A). Silazane treated fumed silica or precipitated silica is described in Smith, US Pat. No. 3,635,743, and Beers, US Pat. No. 3,847,848, incorporated herein by reference.

The filler (B) is generally used at a concentration of 5 to 70 parts, preferably 15 to 50 parts per 100 parts by weight of (A). Preferred fillers are silazane treated fumed silica or a mixture of silazane treated precipitated silica and silazane treated fumed silica. The latter mixture is particularly preferred. This silica mixture should contain fumed silica in relation to precipitated silica in a weight ratio of about 25/1 to about 1/1 and preferably about 10/1 to about 5/1.

The hydroxy containing organopolysiloxane fluid (E) may be added to extend the shelf life of the LIM organopolysiloxane composition. When silazane treated precipitated silica filler is present in the composition, the hydroxy containing organopolysiloxane fluid may be added together with the precipitated silica filler to obtain extended shelf life and release properties. Suitable hydroxy containing organopolysiloxane fluids have a viscosity of about 5 to about 100 cP, preferably about 20 to about 50 cP at 25 ° C. These fluids can be represented by the general formula (8).

R _j (OH) _k SiO _{(4-jk) / 2} (8)

Wherein R is as defined above, j can be 0 to 3, preferably 0.5 to 2.0, k has a value of 0.005 to about 2, and the sum of j and k is 0.8 to 3. Preferably, the hydroxy containing organopolysiloxane fluid is linear with terminal hydroxy substituents.

Silazane-treated sedimentation in component (B) to obtain release properties using a blend of silazane treated precipitated silica and component (E) or to obtain extended shelf life by addition of only (E) The silica should be present at least about 2 parts by weight per 100 parts by weight of (A) and the component (E) should be present at about 1 to about 5 parts by weight per 100 parts by weight of (A).

The component in which the composition (C) is present, ie the first component, is packaged separately from the component in which the component (D) is present, ie the second component, until curing. Components (A), (B), (E) and additives can be distributed between the two components or added to one of them all. In this way it prevents premature reactions during storage and transportation. For the purpose of producing a cured silicone rubber composition, the two components are mixed with each other and the composition is cured for 16 hours at room temperature or for a short curing time at elevated temperature.

The mixed first and second components can be dissolved in a solvent for direct injection molding or for application as a film or coating. In injection molding, the mixing cylinder and shot chamber must be cooled to prevent premature curing. The mold temperature is generally about 150 ° F. to about 500 ° F. Solvents for coating films or coatings include common organic solvents for SiH olefin addition reactants of the prior art. Such solvents include, for example, hexane, heptane, pentane, octane, cyclohexane, toluene, xylene, acetone and the like. Of course, other components may be added to accomplish various purposes. Pigments, thixotropic agents, heat stabilizers and the like can be added according to the teachings in the art. In particular, for catalyzed materials, it is preferable to add an inhibitor such as maleate in order to obtain a suitable working life. Suitable inhibitors are taught in US Pat. No. 4,256,870, which is incorporated herein by reference.

EXAMPLE

[matter]

(A) High viscosity vinyl end-terminated organopolysiloxane

Dimethylvinyl terminated polydimethylsiloxane polymer having a viscosity of 80,000 cP at HVO1-25 °.

Dimethylvinyl terminated polydimethylsiloxane polymer having a viscosity of 4,000 cP at HVO2-25 °.

(B) Low Viscosity Vinyl-Containing Organopolysiloxanes

1 / 1trimethylsilyl / dimethylvinyl terminated polydimethylsiloxane polymer having a viscosity of 500 cP at LVO-25 °.

(C) Chain vinyl group containing organopolysiloxane

A dimethylvinyl terminated poly (dimethyl-methyl-vinyl) siloxane polymer having a viscosity of 500 cP and a vinyl of about 1.65 wt% at VCO1-25 °.

Trimethylsilyl terminated poly (dimethyl-methyl-vinyl) siloxane polymer having a viscosity of 2,000,000 cP and a 13.5 mol% MeVi siloxy at VCO2-25 °.

(D) silica filler

Surface treated with fumed silica-methylcyclic tetramer.

Treated with settling-silica-hexamethyl disilazane.

(E) catalyst

Karstedt platinum catalyst is dissolved in methylvinyl tetramer.

The Lamorox platinum catalyst is dispersed in a concentration of 10% by weight in the LVO1 carrier.

(F) SiH crosslinking agent

A hydride crosslinking agent of formula M ^H ₂ Q having a viscosity of 20 cP and hydrogen at about 0.9 weight percent at RHC-25 ° C.

The linear hydride of the general formula M ^H D _h D _i ^H M ^H having a viscosity of 55 cP and hydrogen H at about 0.8 wt% at LHC-25 ° C. is a crosslinking agent.

(G) hydroxy fluid

Silanol terminated polydimethylsiloxane fluid of the general formula HO-D _6-9 -OH having a viscosity of 30 centistokes at HF-25 ° C.

The following examples are intended to illustrate the invention and are not intended to limit the specification or claims.

[Examples 1 to 7]

The liquid injection molding composition is prepared by first mixing vinyl organopolysiloxane with fumed silica filler. The fumed silica shown above was treated with only cyclic tetramers. The fumed silica filler is treated in situ by adding 6.0 parts by weight of hexamethyldisilazane and 2.0 parts by weight of water. The mixture is heated to 135 ° C. under vacuum. Water and ammonia byproducts are removed during the treatment. Subsequently, the remaining components are added and the resulting composition is injection molded as shown in Table 1.

TABLE 1

* Mixtures mixed up to 40,000 cP at 25 ° C

These examples clearly show that increasing the chain polymer vinyl content while maintaining the SiH / SiVi-ratio produces a high durometer and tear strength material without substantial loss of tensile strength and elongation. The storage stability and releasability of these compositions are poor. In addition, the tear strength did not reach a sufficient level due to the absence of LVO.

Example 8

The process of Examples 1-7 is repeated using the composition of Table 2. The storage stability and releasability of the composition are excellent.

Example 9

The process of Examples 1-7 is repeated using the composition of Table 3. The storage stability and releasability of the composition are poor.

TABLE 2

* Mixed mixture up to 40,000 cP at 25 ° C

** SiH / SiVi ratio: about 1.7

TABLE 3

Claims (12)

(A) linear high viscosity vinyl end-terminated organopolysiloxanes containing up to 25 mole percent (i) phenyl radicals and having a viscosity of about 2,000 to about 1,000,000 cP at 25 ° C., wherein the organo group has 1 to 8 carbon atoms. Selected from the group consisting of lower alkyl radicals, phenyl and trifluoropropyl) 70 to 98 parts by weight, (ii) having at least one terminal vinyl group per molecule, with a vinyl content of 0.01 mol% to 60 mol%, 25 ° C. Linear low viscosity organopolysiloxanes having a viscosity of about 50 to 1,000 cP and containing not more than 25 mol% of phenyl radicals, wherein the organo group is a group consisting of lower alkyl radicals having 1 to 8 carbon atoms, phenyl and trifluoropropyl 1 to 15 parts by weight, and (iii) a chain vinyl group having a vinyl content of about 0.1 to 25 mol%, a viscosity of about 50 to about 100,000 cP at 25 ° C., and containing not more than about 25 mol% of phenyl radicals. contain Organopolysiloxane 1-vinyl-part to 15 parts by weight - containing organopolysiloxane 100 parts by weight of component; The weight ratio of (B) (i) methyl silane or silazane treated fumed silica and (ii) at least 1 part by weight of methyl silane or silazane treated precipitated silica, wherein the weight ratio of fumed silica to precipitated silica is 5 / In the range from 1 to 10/1), about 5 to about 70 parts by weight of the filler or combination of the filler; (C) about 0.1 to 50 parts of a platinum catalyst per million parts of total organopolysiloxane composition; (D) about 0.5 to 25 parts by weight of a SiH composition selected from the group consisting of hydrogen-containing silane and hydrogen-containing organopolysiloxane; And (E) 1 to 5 parts by weight of a hydroxy-containing organopolysiloxane fluid having a viscosity of about 5 to 100 cP at 25 ° C. The composition of claim 1 wherein the high viscosity vinyl end-terminated organopolysiloxane is represented by the following general formula (1).

Wherein Vi is vinyl and R is an organo group selected from the group consisting of lower alkyl radicals of 1 to 8 carbon atoms, phenyl and trifluoropropyl; x may be between 100 and 10,000. The composition according to claim 1, wherein the low viscosity organopolysiloxane is represented by the following general formula (2).

Wherein R is selected from the group consisting of lower alkyl radicals of 1 to 8 carbon atoms, phenyl and trifluoropropyl, R ¹ is the same as R, provided that at least one R ¹ is vinyl and y is 1 to 750 Can be. 4. The composition of claim 3, wherein only one R ¹ is vinyl. The composition according to claim 1, wherein the chain vinyl group-containing organopolysiloxane has 0.5 to 99.5 number% of the units of the following general formula (3) and 99.5 to 0.5 number% of the units of the general formula (4). R _a R ² _b SiO _{(4-ab) / 2} (3) R _c SiO _{(4-c) / 2} (4) Wherein R is selected from the group consisting of monovalent hydrocarbon radicals having up to 20 carbon atoms and halogenated monovalent hydrocarbon radicals, R ² is an olefinic hydrocarbon radical, a has a value from 0 to 2 and the sum of a and b Is 0.8 to 3.0 and c has a value of 0.8 to 2.5. The composition of claim 1 wherein the SiH composition is selected from the group consisting of organopolysiloxanes having from 0.5 to 99.5% by weight of units of formula (6) and from 99.5 to 0.5% by weight of units of formula (4). R _f H _g SiO _{(4-fh) / 2} (6) R _c SiO _{(4-c) / 2} (4) Wherein R is a saturated monovalent hydrocarbon radical and a saturated halogenated hydrocarbon radical having up to 20 carbon atoms, c has a value of 0.8 to 2.5, f has a value of 0 to 2, and the sum of f and g is 0.8 To 3.0. Separately packaged first and second components, wherein either component comprises (A) (i) a linear high viscosity vinyl end containing up to 25 mole percent phenyl radical and having a viscosity of 2,000 to 1,000,000 cP at 25 ° C. Suspended organopolysiloxane, wherein the organo group is selected from the group consisting of lower alkyl radicals of 1 to 8 carbon atoms, phenyl and trifluoropropyl; 70 to 98 parts by weight, (ii) one or more terminal vinyls per molecule Linear low viscosity organopolysiloxanes having groups of from 0.01 mol% to 60 mol%, having a viscosity of about 50 to 1,000 cP at 25 ° C. and containing not more than 25 mol% of phenyl radicals, wherein the organo group 1 to 15 parts by weight and (iii) a vinyl content of about 0.1 to 25 mole percent and a viscosity of about 50 to about 100,000 at 25 ° C. cP 100 parts by weight of all or part of a vinyl-containing organopolysiloxane component composed of 1 to 15 parts by weight of a chain vinyl group-containing organopolysiloxane containing not more than about 25 mol% of phenyl radicals; (B) (i) methyl silane or silazane treated fumed silica, and (ii) methyl silane or silazane treated precipitated silica, wherein the weight ratio of fumed silica to precipitated silica is 5 / Ranges from 1 to 10/1), all or a portion of the filler or combination of fillers, and (E) all or a portion of 1 to 5 parts by weight of a hydroxy-containing organopolysiloxane fluid having a viscosity of about 5 to 100 cP at 25 ° C. Includes; The first component contains (C) 0.1-50 parts of a total amount of platinum catalyst per million parts of the total organopolysiloxane composition, and the second component is a SiH composition selected from the group consisting of (D) hydrogen-containing silane and hydrogen-containing organopolysiloxane Organopolysiloxane composition containing from 0.5 to 25 parts by weight of the total amount, wherein a total of 5 to 70 parts by weight of the filler or the combination of fillers may be distributed between the first component and the second component or added to either component in total. 8. The composition of claim 7, wherein the high viscosity vinyl end-terminated organopolysiloxane is represented by the following general formula (1).

Wherein Vi is vinyl, R is an organo group selected from the group consisting of lower alkyl radicals of 1 to 8 carbon atoms, phenyl and trifluoropropyl, and x may be between 100 and 10,000. 8. The composition of claim 7, wherein the low viscosity organopolysiloxane is represented by the following general formula (2).

Wherein R is an organo group selected from the group consisting of lower alkyl radicals of 1 to 8 carbon atoms, phenyl and trifluoropropyl, R ¹ is the same as R, provided that at least one R ¹ is vinyl and y is It may be 1 to 750. 10. The composition of claim 9, wherein only one R ¹ is vinyl. 8. The composition according to claim 7, wherein the chain-containing vinyl group-containing organopolysiloxane has 0.5 to 99.5% by weight of units of general formula (3) and 99.5 to 0.5% by weight of units of general formula (4). R _a R ² _b SiO _{(4-ab) / 2} (3) R _c SiO _{(4-c) / 2} (4) Wherein R is selected from the group consisting of monovalent hydrocarbon radicals having up to 20 carbon atoms and halogenated monovalent hydrocarbon radicals, R ² is an olefinic hydrocarbon radical, a has a value from 0 to 2 and the sum of a and b Is 0.8 to 3.0 and c has a value of 0.8 to 2.5. 8. The composition of claim 7, wherein the SiH composition is selected from the group consisting of organopolysiloxanes having from 0.5 to 99.5% by weight of units of formula (6) and from 99.5 to 0.5% by weight of units of formula (4). R _f H _g SiO _{(4-fh) / 2} (6) R _c SiO _{(4-c) / 2} (4) Wherein R is a saturated monovalent hydrocarbon radical and a saturated halogenated hydrocarbon radical having up to 20 carbon atoms, c has a value of 0.8 to 2.5, f has a value of 0 to 2, and the sum of f and g is 0.8 To 3.0.