DESCRIPTION

THREE-DIMENTIONAL MOLDED ARTICLE, MANUFACTURING METHOD THEREOF AND USE THEREOF

TECHNICAL FIELD

The present invention relates to a three-dimensional molded article, a manufacturing method thereof, and a use thereof.

Priority is claimed on Japanese Patent Application No. 2006-302815, filed on November 8, 2006, the content of which is incorporated herein by reference.

BACKGROUND ART

It has been well known heretofore to use a silicone rubber with a three-dimensional shape in combination with a substrate made from various materials such as metals, glass and plastics, and several methods have been used for producing those products.

According to a first method, a substrate is placed in a mold cavity in a molding machine, the cavity is filled with an uncured silicone rubber, and the rubber is bonded to the substrate as a result of curing by application of pressure simultaneously with heating. For acceleration of bonding, the substrate can be coated with a primer which is then dried.

According to a second method, a preshaped uncured silicone rubber is placed onto a substrate, and is bonded thereto by curing. Bonding by this method is favorable, particularly for a silicone rubber which is curable by condensation reaction, since it cures at room temperature, and demonstrates strong adhesion to various substrates .

According to a third method, a substrate and cured silicone rubber are bonded to each other by using an adhesive agent. For example, as shown in Figs. 12 to 14 of Japanese Unexamined Patent Application Publication H01-280517, in sealing a tightly closable container with the use of a ring-shaped packing made from silicone rubber, the bonding strength of the ring-shaped packing to a sealing part is improved by preliminarily coating the sealing part with an adhesive agent.

However, for bonding silicone rubber to a substrate, the first method requires the use of a molding machine equipped with a mold, and the bonding operation is difficult on site. Furthermore, since during heating and compression in the mold the content of the mold cavity experiences high pressure developed from mold- closing forces and thermal expansion of the silicone rubber, this method is unsuitable for bonding to a substrate the structure and material of which cannot withstand the above pressures. Moreover, when the substrate has to be precoated with a primer which is to be dried, this method not only requires additional time for application and drying of the primer, but also is associated with

some difficulties that occur when the primer must be correctly applied onto predetermined areas of a substrate if it has a three- dimensional shape. Other problems may occur in connection with impact on the environment caused by evaporation of an organic solvent from the primer.

The second method requires that the uncured silicone rubber maintain a desired shape, until it is cured. When curing requires a longer time, such a method is not applicable for mass production. Furthermore, in forming shapes of an uncured rubber, it is difficult to adjust the shapes, provide shapes of complicated configurations, and maintain dimensional accuracy.

The use of various frames, sealing tapes, or similar means may assist in maintaining the uncured silicone rubber in desired shapes. However, the use of the aforementioned means requires additional time, and does not allow obtaining products of more complicated shapes, as compared to those produced by molding under pressure in molding machines. Furthermore, since forming of silicone rubber with the use of frames and sealing tapes is carried out without application of high pressure, there is a greater chance that the silicone rubber will include air bubbles or will not provide the frame with a sufficient degree of filling.

An advantage of the third method is that a molded silicone rubber being cured with a molding machine can be bonded to a substrate on site with the use of an adhesive agent. However, in a cured state, silicone rubber cannot be easily bonded to a

substrate. The types of adhesive agents that can provide sufficiently strong bonding to substrates are limited. Furthermore, additional time is required for application of the adhesive agents onto the substrates.

In particular, situations are possible when it is necessary to bond cured silicone rubber only to a limited part of a substrate, and to apply a primer only onto a limited part of a substrate. Normally, however, since the primer has low viscosity as well as high permeability and wettability, it is not easy to apply the primer to the limited part.

The present invention is aimed at solving the aforementioned problems of the prior art. More specifically, the objective of the present invention is to provide a new bonding system that makes it possible to easily and quickly bond silicone rubber having any complicated three-dimensional shape to a substrate of any material without the use of a molding machine on site, a primer, or an adhesive agent, in a relatively short period of time, preventing inclusion of air bubbles or other defects in the silicone rubber portion of the obtained product.

DISCLOSURE OF INVENTION

The objective of the present invention can be achieved by a three-dimensional molded article comprising a cross-linked body of

a curable silicone composition, obtained by cross-linking the curable silicone composition wherein at least a portion of the curable silicone composition contacts with a member that has a dielectric constant greater than a dielectric constant of the cross-linked body and that is peelable from the cross-linked body.

It is preferable that the curable silicone composition be one that is curable by a hydrosilylation reaction.

It is preferable that the silicone rubber composition curable by a hydrosilylation reaction comprise: an organopolysiloxane (A) having in one molecule at least two silicon-bonded alkenyl groups; an organopolysiloxane (B) having in one molecule at least two silicon-bonded hydrogen atoms; an adhesion promoter (C) ; and a hydrosilylation catalyst (D) .

The adhesion promoter (C) may comprise an organosilicon compound having in one molecule at least one silicon-bonded hydrolyzable group.

It is preferable that the adhesion promoter (C) comprise an organosilicon compound that contains in one molecule at least one silicon-bonded hydrolyzable group, and at least one silicon-bonded alkenyl group and/or at least one silicon-bonded epoxy group- containing univalent organic group. It is further preferable that the adhesion promoter (C) comprise at least one organosilicon compound selected from the group consisting of an organosilane, an

organopolysiloxane, and a silatrane, each of which contains in one molecule at least one silicon-bonded hydrolyzable group and at least one silicon-bonded epoxy group-containing univalent organic group and/or at least one silicon-bonded alkenyl group.

A three-dimensional molded article of the present invention can be obtained by cross-linking the curable silicone composition wherein at least a portion of the curable silicone composition contacts with a member that has a dielectric constant greater than a dielectric constant of the cross-linked body. The member may be in the form of a film or a sheet. On the other hand, if cross- linking is carried out in a cavity of a mold, the mold may comprise the member, or the member may form only a part of the cavity surface. If cross-linking is carried out on a roll, the roll may comprise the member, or a portion thereof may be made from the member. Alternatively, cross-linking can be carried out when the curable silicone composition is extruded through a nozzle or a die to contact the member.

Various products can be formed by bonding a three- dimensional molded article of the present invention to an arbitrary substrate. Such products are exemplified by fuel cells, portable telephones, automobiles, electric or electronic devices, sporting goods, or construction materials. If necessary, the three-dimensional molded article of the present invention may be handled as a composite formed by integrating this article with a peelable member prior to bonding to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows an example of a golf club produced by using a three-dimensional, molded article of the invention.

Fig. 2 shows an example of a joint produced by using a three-dimensional, molded article of the invention.

Fig. 3 shows an example of a gasket produced by using a three-dimensional, molded article of the invention.

Fig. 4 shows another example of a gasket produced by using a three-dimensional, molded article of the invention.

Fig. 5 shows a third example of a gasket produced by using a three-dimensional, molded article of the invention.

Fig. 6 shows the shape of the cross-linked rubber piece obtained in Example 8.

Fig. 7 shows the shape of the cross-linked rubber piece obtained in Example 9.

BEST MODE FOR CARRYING OUT OF THE INVENTION

The three-dimensional molded article of the present invention comprises a cross-linked (cured) body of a curable silicone composition that can be integrated with a substrate by curing while the article is maintained in contact with the substrate at room temperature or with heating. In the context of

the present invention, the term "room temperature" means a temperature in the range of 20 to 25°C, preferably in the range of 23 to 25°C, and most preferably a temperature of 23°C.

There are no special restrictions with regard to the degree of cross-linking with regard to the cross-linked body. For example, the article of the present invention can be obtained by cross-linking a cross-linkable silicone composition to a condition of complete curing (with a 90 to 100% degree of curing) until substantially no more change occurs in the hardness of the cured product; or the composition can be cross-linked to a condition of incomplete curing wherein the composition is allowed to swell under the effect of a solvent (without completely dissolving in the solvent) in order to reduce flowability, i.e., to a B-stage condition, as defined in JIS K 6800 (Adhesives and Bonding Terminology) so as to perform an intermediate curing of a thermally curable resin. In the cross-linked body, curing can be carried out only in the surface layer without the need to crosslink the interior material. However, complete cross-linking throughout the entire material is preferable.

Furthermore, in the context of the present invention, the term "three-dimensional molded article" means a molded article having a three-dimensional shape, provided that any of the conditions specified below is satisfied. The three-dimensional molded article of the present invention may be solid or hollow, and sponge-like, gel-like, or rubber-like.

(1) A molded article having at least two planes, preferably at least three planes, more preferably at least four planes, further more preferably at least five planes, and most preferably six planes physically intersecting at an acute or obtuse angle wherein the planes may intersect on the surface of the, article or the extended planes may intersect at a position apart from the surfaces of the molded article;

(2) A molded article other than that of item (1) having two parallel planes with the distance between the two parallel planes of no less than 2 mm and preferably 5 mm; and

(3) A molded article, other than those of items (1) and (2), having a curvilinear surface or surfaces.

Specific examples of the three-dimensional article, which should not be construed as limiting the present invention, are spherical; aspherical; elliptical; hemispherical; ring-shaped; polygonal bodies such as cubical and parallelepipedal bodies with the distance between opposite sides of no less than 2 mm and preferably no less than 5 mm; cylindrical; prismatic; conical; and pyramidal bodies; or combinations of the above. In the context of the present invention, thin sheets or films having a thickness less than 2 mm are not defined as three-dimensional articles. However, an article of any shape that satisfies any of the conditions of previously mentioned items (1) through (3) is categorized as a three-dimensional article, even if it has a sheet portion having a thickness less than 2 mm.

It is preferable that the curable silicone composition be one that is curable by a hydrosilylation reaction.

In particular, such hydrosilylation-curable silicone composition may comprise the following components : an organopolysiloxane (A) having in one molecule at least two silicon-bonded alkenyl groups; an organopolysiloxane (B) having in one molecule at least two silicon-bonded hydrogen atoms; an adhesion promoter (C) ; and a hydrosilylation catalyst (D) .

Component (A) , which is a main or base component of the composition, is an organopolysiloxane that contains in one molecule at least two silicon-bonded alkenyl groups. Component (A) may have a linear, partially branched linear, branched, or net-like molecular structure. The silicon-bonded alkenyl groups contained in component (A) may be exemplified by vinyl, allyl, butenyl, pentenyl, or hexenyl groups, of which vinyl groups are preferable. Bonding positions of the alkenyl groups may be located on molecular terminals and/or in side chains. In addition to alkenyl groups, component (A) may also contain other silicon-- bonded groups such as substituted or unsubstituted univalent hydrocarbon groups exemplified by methyl, ethyl, propyl, butyl,

pentyl, hexyl, heptyl, or similar alkyl groups; phenyl, tolyl, xylyl, naphthyl, or similar aryl groups; benzyl, phenethyl, or similar aralkyl groups; chloromethyl, 3-chloropropyl, 3,3,3- trifluoropropyl, or similar halogenated alkyl groups. Most preferable of the above are methyl and phenyl groups. There are no special restrictions with regard to the viscosity of component (A) ; however, for use of the obtained silicone rubber composition as a liquid rubber, it is preferable that viscosity at 25°C be in the range of 100 to 1,000,000 mPa-s . On the other hand, in order to use the obtained silicone rubber composition in a millable form, the viscosity should be greater than 1,000,000 mPa-s, and preferable greater than 10,000,000 mPa-s. Component (A) may consist of one type of organopolysiloxane or may consist of a mixture of organopolysiloxanes of two or more different types.

Component (B) is a cross-linking agent for the composition. This component is an organopolysiloxane having in one molecule at least two silicon-bonded hydrogen atoms. Component (B) may have a linear, partially branched linear, branched, cyclic, or net-like molecular structure. Positions in which hydrogen atoms are bonded to silicone in component (B) may be located on molecular terminals and/or in molecular side chains. In addition to silicon-bonded hydrogen, component (B) may contain other substituted or unsubstituted univalent silicon-bonded hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or similar alkyl groups; phenyl, tolyl, xylyl, naphthyl, or similar aryl

groups; benzyl, phenethyl, or similar aralkyl groups; chloromethyl, 3-chloropropyl, 3, 3, 3-trifluoropropyl, or similar halogenated alkyl groups. Most preferable are methyl and phenyl groups. There are no special restrictions with regard to viscosity of component (B), and viscosity may be in the range of 1 to 100,000 mPa-s. Component (B) may consist of one type of organopolysiloxane or may consist of a mixture of organopolysiloxanes of two or more different types.

Component (B) should be used in an amount sufficient for cross-linking the composition. More specifically, it should be used in an amount such that silicon-bonded hydrogen atoms are contained in an amount of 0.5 to 10 moles, preferably 1 to 3 moles per 1 mole of the silicon-bonded alkenyl groups contained in the composition. If the content of the silicon-bonded hydrogen atoms in the composition is less than the lower limit per 1 mole of the silicon-bonded alkenyl groups, the composition may not be completely cured. If, on the other hand, the mole quantity of the silicon-bonded hydrogen atoms exceeds the upper limit, this may impair the heat-resistant properties of a body obtained by curing the composition.

Component (C) is an adhesion promoter used for imparting favorable adhesion property to the composition. Component (C) may consist of one type of adhesion promoter or may consist of a mixture of adhesion promoters of two or more different types.

Component (C) can comprise an organosilicon compound that contains in one molecule at least one silicon-bonded hydrolyzable group. As an organosilicon compound that contains in one molecule at least one silicon-bonded hydrolyzable group, an organosilicon compound that contains at least two hydrolyzable groups bonded to the same silicon atom is preferable.

Such hydrolyzable groups can be exemplified by methoxy, ethoxy, propoxy, butoxy, methoxyethoxy, or similar alkoxy groups; acetoxy or similar acyloxy groups; isopropenoxy or similar alkenoxy groups; and dimethylketoxime, methylethylketoxime, or similar oxime groups. The use of alkoxy groups, especially methoxy groups, is preferable.

In particular, as the organosilicon compound, an organosilicon compound containing a trimethoxysilyl group is preferable .

Furthermore, in addition to the hydrolyzable groups, the organosilicon compound may contain other silicon-bonded groups which are as follows: substituted or unsubstituted univalent hydrocarbon groups, such as vinyl, allyl, butenyl, pentenyl, hexenyl, or similar alkenyl groups; methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or similar alkyl groups; phenyl, tolyl, xylyl, naphthyl, or similar aryl groups; benzyl, phenethyl, or similar aralkyl groups; chloromethyl, 3-chloropropyl, 3,3,3- trifluoropropyl, or similar halogenated alkyl groups; epoxy group- containing univalent organic groups; acryl group-containing

univalent organic groups such as a 3-methacryloxypropyl group; and hydrogen atoms .

The epoxy group-containing univalent organic group can be exemplified by 3-glycidoxypropyl, 4-glycidoxybutyl, or similar glycidoxyalkyl groups; 2- (3, 4-epoxycyclohexyl) ethyl, 3- (3, 4- epoxycyclohexyl) propyl, or similar epoxycyclohexylalkyl groups; 4-oxylanylbutyl, 8-oxylanyloctyl, or a similar oxylanylalkyl groups .

In order to impart good adhesion properties to various types of substrates, it is preferable that the organosilicon compound contain in one molecule at least one silicon-bonded alkenyl group and/or at least one silicon-bonded epoxy group- containing univalent organic group. In addition to the aforementioned groups, the organosilicon compound may contain a silicon-bonded hydrogen atom or atoms. Such an organosilicon compound may be exemplified by organosilane, organosiloxane, or silatrane. Such an organosiloxane may have a linear, partially branched linear, branched, cyclic, or net-like molecular structure of which the linear, branched, or net-like molecular structure is preferable.

The aforementioned organosilicon compound may be more specifically exemplified by the following.

(1) An organosilane, such as 3- glycidoxypropyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane

(2) An organopolysiloxane, such as a reaction mixture consisting of an epoxy group-containing trialkoxy silane, e.g. 3- glycidoxypropyltrimethoxysilane, and a dimethylsiloxane methylalkenylsiloxane copolymer capped at both molecular terminals with hydroxyl groups; a reaction mixture consisting of an alkenyl group-containing trialkoxysilane, e.g. vinyltrimethoxysilane, a compound containing an epoxy group and an alkenyl group, e.g. allylglycidylether, and a dimethylsiloxane methylhydrogensiloxane copolymer capped at both molecular terminals with trimethylsiloxy groups .

(3) A silatrane, such as bis (trimethoxysilylpropoxymethyl) allylsilatrane of the following formula:

or a silatrane represented by the following formula:

(CH ₃ O) ₃ SiCHaCHgCH

In particular, the reaction mixture consisting of an epoxy group-containing trialkoxysilane, e.g. 3- glycidoxypropyltrimethoxysilane, and a dimethylsiloxane methylalkenylsiloxane copolymer capped at both molecular terminals with hydroxyl groups; bis (trimethoxysilylpropoxymethyl) allylsilatrane; and, the combination thereof are more preferable for the adhesion promoter (C) .

Component (C) should be used in an amount sufficient for imparting good adhesive properties to a cross-linked body of the composition. For example, component (C) can be added in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of component (A). If component (C) is added in an amount less than the lower limit, this may impair adhesive properties of the cross-linked body, and, if, on the other hand, component (C) is added in an amount exceeding the upper limit, this may not only affect the adhesive properties but also impair stability of the cross-linked body.

Component (D) is a catalyst used for accelerating curing of the composition by a hydrosilylation reaction. This component is

represented by a platinum-type catalyst, rhodium-type catalyst, palladium-type catalyst, or a similar known hydrosilylation reaction catalyst. In particular, for acceleration of the reaction, it is preferable to use platinum-type catalysts such as a fine platinum powder, platinum black, platinum carried by a fine silica powder, platinum carried by active carbon, chloroplatinic acid, an alcohol solution of a chloroplatinic acid, an olefin complex of platinum, and an alkenylsiloxane complex of platinum.

Component (D) should be added in an amount sufficient to accelerate cross-linking of the composition. In the case of using a platinum-type catalyst, such a catalyst, in terms of weight units of metallic platinum, should be added in an amount of 0.01 to 1,000 ppm, preferably 0.1 to 500 ppm. If component (D) is added in an amount less than the lower limit, this may delay the speed of cross-linking. If, on the other hand, component (D) is added in an amount exceeding the upper limit, this may not practically accelerate the curing but rather may cause problems associated with coloring of the composition.

The composition of the present invention can be prepared by uniformly mixing components (A) through (D) . A cross-linked body of the composition can be obtained by subjecting the prepared composition to a hydrosilylation reaction at room temperature or by heating the composition at a temperature from room temperature to 200°C, preferably from room temperature to 120 ⁰ C. When the reaction is carried out with heating, it is recommended that an

excessive heat is not left in the composition after the cross- linking process is completed.

In order to adjust the hydrosilylation reaction at the stage of cross-linking and to improve stability of the cured body obtained from the composition, the curable silicone composition of the present invention can be combined with a hydrosilylation reaction inhibitor such as.2-methyl-3-butyn~2-ol, 3-methyl-l- butyn-3-ol, 3, 5~dimethyl-l-hexyn-3-ol, phenylbutynol, or a similar alkyne alcohol; 3-methyl-3-penten-l-yne, 3, 5-dimethyl-3-hexen-l~ yne, or a similar enyne compound; 1, 3, 5, 7-tetramethyl-l, 3, 5, 7- tetravinyl cyclotetrasiloxane; 1, 3, 5, 7-tetramethyl-l, 3, 5, 7- tetrahexenyl cyclotetrasiloxane; or benzotriazole . Amounts in which these addition-reaction inhibitors are added depend on cross-linking conditions of the composition, but in general it is preferable to add the inhibitor in an amount of 0.00001 to 5 parts by weight per 100 parts by weight of component (A) .

If necessary, the curable silicone composition of the present invention can be combined with other arbitrary components such as fillers, e.g., precipitated silica, fumed silica, baked silica, titanium oxide, alumina, glass, quartz, aluminosilicic acid, iron oxide, zinc oxide, calcium carbonate, carbon black, silicon carbide, silicon nitride, boron nitride, or similar inorganic fillers; the aforementioned inorganic fillers treated with organohalosilane, organoalkoxysilane, organosilazane, or similar organosilicon compounds; silicone resin, epoxy resin,

fluororesin, or similar powdered organic resins; silver, copper, or other powdered metals; dyes; pigments; flame retarders; silicone oils; solvents; etc. In particular, when the article is obtained in a mold by, for example, compression or injection molding, the composition may incorporate precipitated silica, fumed silica, carbon black, or a similar component with reinforcement properties that may protect the article from breaking during removal from the mold. In particular, fumed silica may be contained in an amount of 3 to 60 mass%, preferably 5 to 50 mass%, and most preferably, 10 to 40 mass%. When the cross-linked product should be obtained with a sponged structure, various known foaming agents can be used.

In order to reduce hardness of the molded article, improve adhesion to a substrate, or reduce stress of the molded article, the composition may be combined with a silicone oil, in particular diorganopolysiloxane that is free of a cross-linkable reactive group, e.g., in a range of 3 to 400 mass%, preferably 5 to 200 - mass%, and most preferably 10 to 100 mass% of the composition. There are no special restrictions with regard to the viscosity of such a silicone oil at 25 ⁰ C. However, from the viewpoint of ease of handling, it is preferable that the viscosity be in the range of 50 to 50,000 mPa--s. It is preferable that such a silicone oil comprise a diorganopolysiloxane that has the same groups as the silicon-bonded groups other than alkenyl groups of component (A) , i.e., a silicone oil that is highly compatible with component (A) .

On the other hand, when it is necessary to use silicone oil that will bleed-out to the surface of the molded article for imparting to the article's surface lubricating properties, it is preferable to select a diorganopolysiloxane that contains no cross-linkable group and has low compatibility with respect to component (A) , which is to be contained in the composition in an amount of 1 to 10 mass%. If necessary, the composition may be combined with both a silicone oil compatible with component (A) and a silicone oil not compatible with component (A) .

The following is a more detailed description of a method for manufacturing three-dimensional molded articles from the curable silicone composition of the present invention.

A three-dimensional molded article of the present invention can be obtained by cross-linking and molding the aforementioned cross-linkable silicone composition wherein it contacts with a member that is peelable from the cross-linked body of the composition and has a dielectric constant greater than a dielectric constant of the cross-linked body. There are no special restrictions with regard to the method. A method for cross-linking the curable silicone composition in a mold, such as compression molding, injection molding, transfer molding, injection and compression molding, casting, or another method of molding, may be used (hereinafter such a method will be referred to as "molding with the use of a mold") .

An example of preferred molding with the use of a mold consists of providing a member in the form of a film or sheet that is peelable from the cross-linked body of the curable silicone composition and has a dielectric constant greater than a dielectric constant of the cross-linked body, and then placing the member into the cavity of the mold. More specifically, in compression or injection molding, the film or sheet of that member may be placed into the entire or a part of the cavity of the mold. The cavity of the mold is then filled with the curable silicone composition. When cross-linking is then carried out under a given pressure and temperature, it becomes possible to obtain a three- dimensional article that repeats the shape of the cavity, since the film or sheet takes the shape of the cavity. At the same time, the part of the surface of the three-dimensional article that is in contact with the film or sheet located in the cavity acquires adhesion properties.

If only a part of the film or sheet is placed into the cavity, adhesive properties will be imparted only to a part of the molded article. When the molded article is removed from the cavity, the film or sheet can remain attached to the molded article. If peelability of the molded article or of the film or sheet from the cavity surface is impaired, the peelability can be improved by pre-coating the surface of the cavity with a known mold-release agent, or by subjecting the surface of the mold

cavity beforehand to a conventional surface treatment with the use of a fluororesin, or the like.

If the film or sheet cannot follow the shape of the cavity because of extreme softness or low strength, the film or sheet can be made of two layers by coating the material of the member on the surface of another film or sheet that can follow the shape of the cavity. An example of a film or sheet that can follow the shape of the cavity is a polyester film or sheet, in particular, a polyethyleneterephthalate film or sheet. Furthermore, the film or sheet of the member can be initially flat and take the required shape only when it is placed into the cavity, or the film or sheet can be pre-shaped in accordance with the profile of the cavity and used in the pre-shaped form.

Another example of a method of molding with the use of a mold consists of manufacturing a mold from the material of the member that possesses mold-release properties with respect to a cross-linked body and has a dielectric constant greater that that of the cross-linked body of the curable silicone composition, or making at least a part of the mold cavity from the material of the member, and then cross-linking and molding the aforementioned composition in the mold.

The method of making at least a part of the cavity surface from the material of the member can be carried out by coating the surface of the cavity with that material. When it is necessary to impart adhesive properties to the entire three-dimensional molded

article, the entire surface of the cavity is coated with that material. When it is necessary to impart adhesive properties only to a part of the three-dimensional molded article, the coating is applied only onto the appropriate part of the cavity surface. Coating can be carried out by a conventional method. For example, if the member is made from a resin, the member is heated to a molten state and then used for coating, or the material of the member can be dissolved in a solvent, and then the solution is applied as a coating. On the other hand, the member with a predetermined shape can be used as an insert to a part of the mold so that the surface of the member forms a part of the cavity surface. When the mold-release properties on the surfaces of the molded article and the cavity are insufficient to improve these properties, the surface of the cavity may be coated with a known mold-release agent or pre-treated in a known manner with fluororesin, or the like.

When the curable silicone composition is a liquid, the composition may be supplied into the mold cavity without application of pressure and molding (casting) may be carried out by cross-linking the composition at room temperature or with heat.

According to another method, molding can be carried out by means of extrusion wherein the curable silicone composition is extruded through a die or nozzle and is brought into direct contact with a member, the material of which possesses mold- release properties with respect to the cross-linked body of the

composition and has a greater dielectric constant than that of the cross-linked body, followed by cross-linking with heat, or the curable silicone composition is excluded through a die or nozzle with a member, followed by cross-linking with heat. At least a part of the surface or the entire surface of the die or nozzle through which the curable silicone composition is extruded can be made from the aforementioned member. For example, the inner surface of the die or nozzle can be coated with the material of the member in the same manner as described above, or the die or nozzle can be formed by the material of the member.

According to yet another method, molding can be carried out by calendar molding on a roll comprising a member, the material of which possesses the property of peelability with respect to the cross-linked body of the composition and that has a dielectric constant greater than that of the cross-linked body. In the aforementioned calendar molding method, at least a part or the entire surface of the roll can be made from the member. For example, the surface of the roll can be coated with the material of the member by the method described above. The rolls may incorporate a heating function. The distance between the rolls can be adjusted, and the surface of the rolls can be formed with projections and recesses, etc., so that instead of thin sheets or films having smooth surfaces, the three-dimensional articles can be produced with embossed surfaces.

Still another method can comprise cross-linking of a curable silicone composition after screen printing the curable silicone composition on a member made from a material peelable from the cross-linked body of the composition and having a dielectric constant greater than that of the cross-linked body.

In the above-described methods, the temperature of the mold ranges from room temperature to 200°C, preferably from room temperature to 120°C. If the temperature of the mold is too low, molding may take too much time. On the other hand, if the temperature of the mold is too high, this may either impair peelability of the member from the molded article or impair adhesive properties of the molded article. Furthermore, it is preferable to remove the molded article from the mold after completion of cross-linking so as not to transfer excessive heat to the molded article. The duration of cross-linking should be in the range of 0.7 to 10 times, preferably 0.9 to 3 times that of 90% vulcanization duration, as specified by JIS K 6300-2 (Determination of Cure Characteristics of Rubber with Oscillating Curemeters) . If the duration of cross-linking is shorter than the lower limit, the cross-linked body may have insufficient strength, or may either be difficult to handle or have insufficient strength after bonding. On the other hand, if the application of heat continues after cross-linking, this may either impair peelability from the member or impair adhesive properties of the molded article.

The following is a more detailed description of the member which has good peelability from the cross-linked body made from the curable silicone composition, and a greater dielectric constant than that of the cross-linked body.

During cross-linking, the member should be maintained in contact with the three-dimensional molded article of the present invention so that the surface of the three-dimensional molded article can develop adhesive properties. There are no special restrictions with regard to the shape of the member, and the member can be made in the form of a film, sheet, rod, plate, cylinder, or a body of any arbitrary geometrical shape. If necessary, the member can be pre-shaped in accordance with the profile of the three-dimensional molded article.

The material of the member can be exemplified by the following: metal oxide or a similar inorganic substance; and a polyester resin, a polyimide resin, a polyether resin, a polysulfone resin, an epoxy resin, a cellulose resin, a phenol resin, a polyamide resin, or a similar organic resin. Members made from organic resins are preferable; most preferable are those made from a polyether resin and a cellulose resin, in particular from polyether sulfone, polyether ether ketone, or a cellulose acetate resin. Members made from organic resins can consist entirely of an organic resin or may have a composite structure in which an organic resin is used on the surface or inside the

material of the member. An example for the composite member is a member prepared by coating an organic resin onto the surface of another kind of organic resin.

If the curable silicone composition is cross-linked and molded with the mold, die, nozzle or roll, the entire or a part of which is made from the member, and the molded article is stored prior to the bonding process, it is preferable that the surface of the molded article is protected with a protective film or sheet in order to prevent exposure of the surface thereof to moisture in the air, or the molded article is stored in a dry atmosphere or in a film bag or similar container. There are no special restrictions with regard to the dielectric constant of the protective material. For example, it may comprise a film, sheet, or a film bag made not only from a resin of a high dielectric constant, such as polyester, but also from materials such as a fluororesin, a polyethylene resin, a polypropylene resin, or a silicone resin. The cross-linked body of the curable silicone composition of the present invention can be such a peelable protective material, if the non-adhesive surface portion of the body is closely contacted with the adhesive surface portion of another cross-linked body. Moreover, in order to prevent the loss of adhesive properties during long-term storage, it is preferable to store the article below room temperature, preferably below 10 ⁰ C,

Uses of the three-dimensional molded article of the present invention will now be described in more detail.

The three-dimensional molded article of the present invention may adhere to a substrate by contacting the surface having adhesive properties of the article with a predetermined part of the substrate at room temperature or under heating conditions. The three-dimensional, molded article of the present invention can be used for various applications in which the bonding to substrates is required, as sealing elements such as seal rings, packings, gaskets, grommets, rubber plugs, and boots.

There are no special restrictions with regard to substrate materials, and they can be made from metal, glass, resin, rubber, etc. The metal can be exemplified by iron, aluminum, copper, nickel, chromium, etc. The resin can be exemplified by a polyethyleneterephthalate resin, a polybutylenephthalate resin, a polyphenylene sulfide resin, an acrylonitrile-butadiene-styrene copolymer, a vinylchloride resin, a polycarbonate resin, a polyamide resin, a polyimide resin, etc.

When the substrate is integrated with the three-dimensional molded article of the present invention by tightly and thermally bonding to the surface of the article, the temperature is preferably in the range of 70 to 200°C, more preferably from 100 to 160°C. If the temperature is below the lower limit, this may delay the bonding operation and weaken the bonding force; if the temperature is too high, this may either damage the substrate or

cause deformation of the substrate. Also, there are no special restrictions with regard to the duration of heating, and depending on the type of substrate, the appropriate duration can be selected from one minute to several hours. On the other hand, bonding can be carried out at room temperature if the substrate is one that provides ease of bonding, such as glass. If necessary, two three- dimensional molded articles can be bonded to each other. In this case, adhesive surface portions of the articles are closely contacted with each other for several days at room temperature, and as a result, a pair of cross-linked rubber pieces is bonded together. In order to provide reliable contact between the three- dimensionally molded article and the substrate, pressure can be applied to the area of contact between the article and the substrate . There are no special restrictions with regard to the magnitude of the pressure, and the pressure can be appropriately selected with reference to the type of substrate.

The products obtained by bonding substrates to three- dimensional molded articles of the present invention can be used in various fields of industry. For example, the three-dimensional molded articles of the present invention can be combined with various substrates to form sealing elements such as water-proof, dust-proof, gas-proof, or liquid-proof gaskets, packings, grommets, rubber plugs, and boots. The three-dimensional molded articles of the present invention can be used as stress-relaxation and impact- absorbing or vibration-damping elements to form, in combination

with various substrates, various bushings, mounts, hangers, dampers, bearings, etc. The three-dimensional molded articles of the present invention can be combined, as resilient elements, with various substrates in order to form switches, rubber springs, rubber valves, valves, diaphragms, rubber joints, etc. For example, in the automotive industry, the product of the present invention can be used in the structure of engine gaskets, various pipe couplings, door moldings, window-glass seals, window strips, dust boots, engine mounts, anti-vibration bushes or mounts, grommets, diaphragms, and connectors for wire harnesses. Examples of use in electrical and electronic parts are precision instrument cases for mobile devices and hard disks, connectors, key-pads, key switches, cable accessories for electrical connectors, and gaskets for fuel-cell separators. Examples of use in construction materials are various gaskets for use in SSG (Structural Sealant Glazing) processes, gasket-attached glass, curtain walls, joint- hiding gaskets, feedthrough gaskets, or rubber joints. Examples of use in sports goods are golf clubs or tennis rackets.

Fig. 1 illustrates an example of a golf club 1 that uses the three-dimensional molded article of the present invention. Fig. 1 (a) shows an overall view of the golf club 1 and Fig. l(b) shows a cross-sectional view of the grip part of the golf club 1. As shown in Fig. l(a), the golf club 1 consists of a grip 3 attached to the grip part of the shaft 2 and a head 4 attached to

the other end of the shaft 2. As shown Fig. 1 (b) , the grip 3 has an approximate cylinder shape in which one end is closed and the grip part of the shaft 2 is inserted into the interior space of the grip 3.

In the example shown in Fig. 1, adhesion is imparted to the inner surface 3a of the grip 3 that correspond to the three- dimensional molded article of the present invention. Thus, in the example shown in Fig. 1, the grip part of a shaft 2 is inserted into the interior space of the grip 3, and then, for example, the shaft 2 and the grip 3 are heated, whereby a golf club 1 composed of two mutually bonded parts can be formed.

Fig. 2 illustrates an example of a joint that uses the three-dimensional molded article of the present invention. In the example shown in Fig. 2, a joint 5 is composed of a female thread 6, a male screw 7, and a ring-shape packing 8 that corresponds to the three-dimensional molded article of the invention. In Fig. 2, the packing 8 is placed between the female thread 6 and the male screw 7. The packing 8 having an adhesive surface portion at a periphery 8a is put into the opening part of the female thread 6, the male screw 7 is threaded into the female thread 6, and then the integrally assembled joint 5 is left at rest or heated, whereby a joint 5 having excellent sealing can be formed. Since the packing 8 is bonded to the female thread 6, dropout of the packing 8 can be prevented when the male screw 7 is detached from

the female thread 6. In addition, since the packing 8 can be a simple shape, it has an advantage on manufacturing cost.

Fig. 3 illustrates a cross sectional view of an example of a gasket that uses the three-dimensional molded article of the present invention. Fig. 3 (a) illustrates a semifinished product which is prepared by bonding a gasket 10 that corresponds to the three-dimensional molded article of the present invention on a substrate 9. In Fig. 3 (a), the gasket 10 has adhesive surface portions on an under surface 10a and an upper surface 10b. In Fig, 3 (a), the upper ^' surface 10b of the gasket 10 is covered with a film 11 having a dielectric constant greater than the dielectric constant of the gasket 10 and that is peelable from the gasket 10. As shown in Fig. 3 (b) , the film 11 is peeled off and then the upper surface 10b of the gasket 10 is bonded to a substrate 12, whereby a final product can be obtained. In the example shown in Fig. 3, since the gasket 10 is integrated with both of the substrates 9 and 10 firmly, the final product has excellent sealing.

Fig. 4 illustrates a cross sectional view of another example of a gasket that uses the three-dimensional molded article of the present invention. In Fig. 4, a gasket 15 that corresponds to the three-dimensional molded article of the invention is placed in a concavity of the substrate 13. Since the under surface of the gasket 15 is imparted adhesiveness, the gasket 15 is bonded to the bottom surface of the concavity of the substrate 13. In the

example shown in Fig. 4, since the gasket 15 does not bond to the substrate 14, the gasket 15 can maintain sealing by sliding and maintain contact to the surface of the substrate 14 when the relative position between the gasket 15 and the substrate 14 is changed in the horizontal direction.

Fig. 5 illustrates a cross sectional view of a third example of a gasket that uses the three-dimensional molded article of the present invention. An adhesive surface portion 18a of a gasket 18 is bonded on the edge of an external wall of a vessel 16 In Fig. 5, since the vessel 16 and the lid 17 are sealed with the gasket 15, the air tightness of the internal space should be kept.

The three-dimensional molded article can be handled as a composite consisting of a three-dimensional molded article, and a member peelable from this body. In this case, storage and transportation are facilitated. There are no special restrictions with regard to the material and shape of the member, but it is preferable that the material of the member has a dielectric constant greater than that of the cross-linked body of the curable silicone composition and be made from a material that can be peeled from the cross-linked body.

INDUSTRIAL APPLICABILITY

The three-dimensional molded article of the present invention can be easily handled, since the same can be premolded to a complicated shape with the use of a molding machine and a mold, and is already cured prior to bonding. This makes it possible to perform bonding on site, because the bonding process does not need the use of molding machines during the stage of bonding of the three-dimensional molded article of the present invention to a substrate. Furthermore, such a procedure is advantageous from the viewpoint of shortening the time required for application of a primer, as well as from the viewpoint of reduced production costs and impact on the environment since bonding of such an article does not require use of a primer on the surfaces of a substrate. Furthermore, since a substrate is not placed into the mold cavity, it is possible to perform bonding to a substrate made from a material and having a structure which might not be able to withstand the high pressures developed in the mold.

Moreover, the three-dimensional molded article of the invention makes it possible to perform the bonding operation in a relatively short period of time, because the same already has a shape, and is free of problems associated with maintaining the uncured silicone rubber in a predetermined shape on site. Further, the above-described method can prevent the formation of air bubbles in the cured silicone rubber to be bonded to a substrate, thus minimizing defects in the obtained product.

The three-dimensional molded article of the present invention, while comprising a cross-linked silicone rubber, allows bonding to various substrates without the use of adhesive agents. Furthermore, adhesive properties can be selectively imparted, during molding, to some areas on the surface of the three- dimensional molded article. Therefore, during integration thereof with a substrate, the adhesive and non-adhesive surface portions of the article can be reliably separated.

In the method of the present invention, the three- dimensional molded article with the excellent properties described above can be produced by injection molding, compression molding, cast molding, extrusion molding, calendar molding, or other known molding processes or printing methods such as screen printing or i the like.

The products of the present invention composed of the three- dimensional molded article and a substrate are characterized by accurate positioning of an interface between the bonded parts and by high durability which provides long service life. In particular, the products of the present invention are applicable in fields such as fuel cells, portable telephones, automobile parts, parts of electric and electronic devices, sporting goods, and construction materials that require precise bonding of parts. Another specific application relates to connectors. A further advantage of the three-dimensional molded article of the present invention is that, by forming a composite of the molded article

and a peelable member that can be peeled from the article, it becomes possible to facilitate transportation and storage of the article .

EXAMPLES

The invention will be described in more detail by way of examples, which however should not be construed as limiting the scope of the invention. In the subsequent examples, all values of viscosity were obtained at 25°C.

[Preparation Example 1]

A Ross mixer was filled with 85 parts by mass of a dimethylpolysiloxane capped at both molecular terminals with dimethylvinylsiloxy groups (viscosity: 40,000 mPa ^• s ; vinyl group content: about 0.09 mass%); 15 parts by mass of a dimethylpolysiloxane capped at both molecular terminals with dimethylvinylsiloxy groups (viscosity: 2,000 mPa-s; vinyl group content: about 0. 23 mass%); and 11 parts by mass of fumed silica that has a BET-specific surface area of 200 m ² /g and has been surface-treated with hexamethyldisilazane . The components were mixed to uniformity at room temperature, and after two hours of heat treatment at 180 ⁰ C and under reduced pressure, a flowable Master Batch 1 was obtained.

[Preparation Example 2]

A kneader mixer was filled with 100 parts by mass of an uncured rubber of a dimethylsiloxane-methylvinylsiloxane copolymer

(molecular weight: about 500,000; vinyl group content: about 0.065 mass%); 15 parts by mass of a dimethylsiloxane capped at both molecular terminals with dimethylhydroxysiloxy groups (viscosity: 40 mPa-s); and 40 parts by mass of fumed silica having a BET- specific surface area of 300 m ² /g. The components were mixed to uniformity at room temperature, and after 1.5 hours of heat treatment at 180°C, a miliable rubber-type Master Batch 2 was obtained.

[Preparation Example 3]

A Ross mixer was filled with 100 parts by mass of a dimethylpolysiloxane capped at both molecular terminals with dimethylvinylsiloxy groups (viscosity: 40,000 mPa-s; vinyl group content: about 0.09 mass%); 0.2 parts by mass of a dimethylsiloxane-dimethylvinylsiloxane copolymer capped at both molecular terminals with dimethylhydroxysiloxy groups (viscosity: 20 mPa-s); 40 parts by mass of fumed silica having a BET-specific surface area of 225 m ² /g; 7 parts by mass of hexamethyldisilazane; and 2 parts by mass of water. The components were mixed to uniformity at room temperature, and after two hours of heat treatment at 200°C and under reduced pressure, a flowable Master Batch 3 was obtained.

[Preparation Example 4]

48 mass% of 3-glycidoxypropyltrimethoxys±lane and 52 mass% of a copolymer of dimethylsiloxane methylvinylsiloxane capped at both molecular terminals with hydroxyl groups (viscosity: 20 mPa-s; vinyl group content: about 11 mass%) were condensed under the presence of potassium hydroxide as a condensation catalyst, and after neutralization and filtration, an Adhesion Promoter 1 having a viscosity of 20 mPa-s was obtained.

[Example 1]

A curable silicone rubber composition (with a 1.1 ratio of the total content of hydrosilyl groups to the content of vinyl groups in the composition) was prepared by uniformly mixing the following components: 96 parts by mass of Master Batch 1; 1.0 part by mass of a dimethylsiloxane-methylhydrogensiloxane copolymer capped at both molecular terminals with trimethylsiloxy groups and having a kinematic viscosity of 55 mm ² /s (content of silicon- bonded hydrogen atoms: about 0.70 mass%); 0.32 parts by mass of a platinum-type catalyst (1, 3-divinyltetramethyldisiloxane solution of a platinum complex with 1, 3-divinyltetramethyldisiloxane; weight content of metal platinum: about 4,000 ppm) ; 0.6 parts by mass of Adhesion Promoter 1; 0.3 parts by mass of bis

(trimethoxysilylpropoxymethyl) allylsilatrane (adhesion-promoter) ; and 2.0 parts by mass of a mixture (curing inhibitor) of 0.5 parts

by mass of phenylbutynol and 99.5 parts by mass of dimethylpolysiloxane capped at both molecular terminals with dimethylvinylsiloxy groups (viscosity: 10,000 mPa-s) .

A film obtained by coating a polyethyleneterephthalate film with polyethersulfone (PES) having a dielectric constant of 3.5 (hereinafter referred to as "PES film") was placed into a mold so that the surface of the mold cavity became the PES surface, and the cavity was then filled with the previously prepared curable silicone rubber composition, which was subjected to compression- molding for 5 minutes at 100°C and under a pressure of 20 MPa. As a result, a cross-linked rubber piece having a sheet-like part attached to the film was obtained. The sheet-like part had a 2 mm thickness, a 2.5 cm width, and a 10 cm length.

The obtained cross-linked rubber piece was held for 24 hours at room temperature. The film was peeled off, and the sheet-like part was maintained attached, for 60 minutes at 150°C, to various substrates (glass, SUS 304 steel, and aluminum) , whereby the cross-linked rubber piece was bonded to the substrate. In order to prevent destruction of the bonding interface caused by the difference of thermal expansion ratio between the cross-linked rubber piece and the substrate, the piece was sandwiched between aluminum plates and adhered by applying pressure to the mating parts with the use of metal clamps.

[Example 2]

A curable silicone rubber composition (with a 1.1 ratio of the total content of hydrosilyl groups to the content of vinyl groups in the composition) was prepared by uniformly mixing the following components: 99 parts by mass of Master Batch 2; 0.69 parts by mass of dimethylpolysiloxane capped at both molecular terminals with dimethylhydrogensiloxy groups and having a kinematic viscosity of 15 mm ² /s (content of silicon-bonded hydrogen atoms: about 0.83 mass%); 0.1 parts by mass of a platinum-type catalyst (1, 3-divinyltetram.ethyldisiloxane solution of a platinum complex with 1, 3-divinyltetramethyldisiloxane; weight content of metal platinum: about 4,000 ppm) ; 0.53 parts by mass of Adhesion Promoter 1; 0.26 parts by mass of bis (trimethoxysilylpropoxymethyl) allylsilatrane (adhesion- promoter); and 0.014 parts by mass of 2-methyl-3-butyn-2-ol (curing inhibitor) .

A PES film was placed into a mold to form the surface of the cavity. The cavity was filled with the previously obtained curable silicone rubber composition, and compression-molding was carried out for 10 minutes at 100°C under a pressure of 20 MPa. As a result, a cross-linked rubber piece having a sheet-like part attached to the film was obtained. The sheet-like part had a 2 mm thickness, a 2.5 cm width, and a 10 cm length.

The obtained cross-linked rubber piece was held for 24 hours at room temperature. The film was peeled off, and the sheet-like part was maintained attached, for 60 minutes at 150°C,

to various substrates (glass, PBT (polybutyleneterephthalate) , SUS 304 steel, and aluminum) , whereby the cross-linked rubber piece was bonded to the substrate. Similar to Example 1, the piece was sandwiched between aluminum plates and adhered by applying pressure to the mating parts with the use of metal clamps.

[Example 3]

A curable silicone rubber composition (with a 1.1 ratio of the total content of hydrosilyl groups to the content of vinyl groups in the composition) was prepared by uniformly mixing the following components: 45 parts by mass of Master Batch 3; 53 parts by mass of dimethylpolysiloxane capped at both molecular terminals with dinαethylvinylsiloxy groups and having a viscosity of 40,000 mPa-s (content of vinyl groups: about 0.09 mass%); 0.73 part by mass of a copolymer of methylhydrogensiloxane and dimethylsiloxane capped at both molecular terminals with trimethylsiloxy groups (kinematic viscosity:

55 mm ² /s; content of silicon-bonded hydrogen atoms: about 0.70 mass%; 0.3 parts by mass of a platinum-type catalyst (1,3- divinyltetramethyldisiloxane solution of a platinum complex with 1, 3-divinyltetramethyldisiloxane; weight content of metal platinum: about 4,000 ppm) ; 0.38 parts by mass of Adhesion Promoter 1; 0.19 parts by mass of bis (trimethoxysilylpropoxymethyl) allylsilatrane (adhesion-

promoter); and 0.17 parts by mass of 2-methyl-3-butyn-2-ol (curing inhibitor) .

A film obtained by coating a polyethyleneterephthalate film with cellulose acetate having a dielectric constant of 5.5 (hereinafter referred to as "cellulose acetate film") was placed into a mold so that the surface of the mold cavity became the cellulose acetate surface, and the cavity was then filled with the previously prepared curable silicone rubber composition, which was subjected to compression-curing for 5 minutes at 100°C and under a pressure of 20 MPa. As a result, a cross-linked rubber piece having a sheet-like part attached to the film was obtained. The sheet-like part had a 2 mm thickness, a 2.5 cm width, and a 10 cm length.

^• The obtained cross-linked rubber piece was held for 24 hours at room temperature. The film was peeled off, and the sheet-like part was maintained attached, for 30 minutes at 150 ⁰ C, to various substrates (glass, PBT, SUS 304 steel, and aluminum), whereby the cross-linked rubber piece was bonded to the substrate. Similar to Example 1, the piece was sandwiched between aluminum plates and adhered by applying pressure to the mating parts with the use of metal clamps.

[Comparative Example 1]

Each of the substrates was bonded to the cross-linked rubber piece in the same manner as in Example 3, except that a

polytetrafluoroethylene film having a dielectric of 2.1 was used instead of the cellulose acetate film.

The adhesion forces of the cured rubber pieces to various substrates obtained in Examples 1 to 3 and in Comparative Example 1 were measured. Measurements of the adhesion forces were carried out with use of Autograph AGS-50D of Shimazu Seisakusho Co., Ltd. by conducting a 180° peeling test. The adhesion forces were measured in terms of peeling force (N/cm) per width of the cured rubber piece. The results are shown in Table 1. In Table 1, symbol "CF" means that the peeling mode on the interface surface was a cohesive failure.

Table 1

In addition, various physical properties listed in Table 1 were measured with regard to the cross-linked rubber-pieces

produced under the same conditions as in Examples 1 to 3 and Comparative Example 1, but without the use of a PES film, a cellulose acetate film, and a polytetrafluoroethylene film. These properties were measured by the following methods:

Hardness: Measured by Type-A Durometer as specified in JIS K6253

Density: Measured by Automatic Densitometer D-IOO (product of Toyo Seiki Seisakusho Company, Ltd.

Tensile and Tear Strength: Measured as specified by JIS K6251 and K6252

100% Modulus: Measured in terms of stress generated during 100% extension of a No. 3 Dumbbell specimen as specified by JIS K6251

Dielectric Constant: Measured by Automatic Instrument TR- 1100 for measurement of dielectric constants (product of Ando Electric Co., Ltd.)

[Example 4]

A curable silicone-rubber composition (with a 1.1 ratio of the total content of hydrosilyl groups to the content of vinyl groups in the composition) was obtained by the same method as in Example 3.

A cellulose acetate film was placed into a mold so that the surface of the mold cavity became the cellulose acetate surface, and the cavity was then filled with the previously prepared

curable silicone rubber composition, which was subjected to press vulcanization for 2 minutes at 100°C and under a pressure of 20 MPa. As a result, a cross-linked rubber piece having a sheet-like part attached to the film and having a 2mm thickness, a 2.5cm width, and a 10cm length was obtained. Physical properties of the cross-linked rubber piece obtained under the same conditions as in Example 4 but without the use of the cellulose acetate film were the same as in the case of Example 3.

The obtained cross-linked piece was held for 24 hours at room temperature. The film was peeled off, and the sheet-like part was maintained attached, for 240 minutes at 23 ⁰ C, to a glass substrate, whereby the cross-linked rubber piece was bonded to the substrate. Measurement of the adhesion force was carried out with use of Autograph AGS-50D of Shimazu Seisakusho Company, Ltd. by conducting a 180° peeling test. The adhesion force was 2.3 N/cm.

Thus, it is understood from the results obtained above that bonding can be carried out at room temperature with the use of easily bondable substrates such as those made from glass.

[Example 5]

A curable silicone-rubber composition (with a 1.1 ratio of the total content of hydrosilyl groups to the content of vinyl groups in the composition) was obtained by the same method as in Example 3.

A PES film was placed into a mold so that the surface of the mold cavity became the PES surface, and the cavity was then filled with the previously prepared curable silicone rubber composition, which was subjected to press vulcanization for 2 minutes at 100°C and under a pressure of 20 MPa. As a result, two cross-linked rubber pieces each of which has a sheet-like part attached to the film were obtained. The sheet-like part has a 2 mm thickness, a 2.5 cm width, and a 10 cm length. In addition, physical properties were measured for the cross-linked rubber piece obtained under the same conditions as in Example 5, but without the PES film. The properties were the same as in the case of Example 3.

The obtained two cross-linked rubber pieces with the films were held for 24 hours at room temperature. The films were peeled off, and the peeled surfaces were closely contacted with each other for three days at 23°C. As a result, a pair of cross-linked rubber pieces was bonded together. Measurement of the adhesion force was carried out with use of Autograph AGS-50D of Shimazu Seisakusho Company, Ltd. by conducting a 180° peeling test. The adhesion force was 5.2 N/cm.

[Example 6]

The test and measurement of the adhesive force were repeated under the same conditions as in Example 5, except that the peeled-off surfaces of the two cross-linked rubber pieces were

contacted together for 7 days. The measured adhesive force was 14 N/crα. In addition, physical properties were measured for a cross- linked rubber piece obtained under the same conditions as in Example 6, but without the PES film. The properties were the same as in the case of Example 3.

[Example 7]

The test and measurement of the adhesive force were repeated under the same conditions as in Example 5, except that peeled-off surfaces of the two cross-linked rubber pieces were contacted together for 21 days. The measured adhesive force was 21 N/cm. In addition, physical properties were measured for a cross-linked rubber piece obtained under the same conditions as in Example 7, except that the PES film was not used. The properties were the same as in the case of Example 3.

[Example 8]

The test was repeated under the same conditions as in Example 3, except that the mold was replaced with a new one for molding a ring-shaped cross-linked rubber piece with the approximate shape as shown in Fig. 6, having a 100 mm-diameter and a 5 mm-diameter of cross section, and a cellulose acetate film was applied only to a part of the surface of the ring. The obtained ring-shaped piece was bonded to various substrates (glass, PBT, SUS 304 steel, and aluminum) . Measurements of the adhesion force

were carried out with use of Autograph AGS-50D of Shimazu Seisakusho Company, Ltd. by conducting a 180° peeling test and showed a cohesive failure.

[Example 9]

A polyether sulfone (PES) having the dielectric constant of 3.5 (Sumika Excel 4100P, sold by Sumitomo Chemical Co., Ltd.) was dissolved in a mixture composed of 1, 1, 2-trichloroethane and dichloromethane mixed in a 1:1 mass ratio so as to a obtain a 10 mass% PES solution. The obtained PES solution was applied by a brush as a thin layer onto the surface of a cavity of a mold made from steel (S55C) , the coating was dried for 1 hour at room temperature, and then baked at 320°C in a hot-air-circulation-type oven.

A curable silicone rubber composition with a 1.1 ratio of the total content of hydrosilyl groups to the content of vinyl groups in the composition was obtained by the same procedure as in Example 3.

The obtained curable silicone rubber composition was used for producing a cross-linked rubber piece having a sheet-like part with a thickness of 2 mm, a width of 2.5 cm, and a length of 10 cm, by injection molding (temperature: 100 ⁰ C; mold retention time: 1 min.). Physical properties measured for the cross-linked rubber piece obtained under the same conditions as in Example 9 but

without the use of the PES coating were yet the same as in Example 3.

After removal of the cross-linked rubber piece from the mold cavity, the surface thereof was covered with a 2 mm-thick polyethyleneterephthalate film, as shown in Fig. 7, and the piece was held for 24 hours at room temperature. Following this, the film was peeled off, and the sheet-like part was held in contact with a glass substrate and a SUS 304 substrate, respectively, for 60 min . at 150 ⁰ C, whereby the cross-linked rubber piece was bonded to each of the substrates. Similar to the procedure of Example 1, the cross-linked rubber piece was bonded to the substrate by sandwiching them between flat aluminum plates with application of pressure .

Measurements with use of Autograph AGS-50D of Shimazu Seisakusho Company, Ltd. by conducting a 180° peeling test in both cases showed a cohesive failure. It can be concluded from these results that injection molding also provides strong adhesion.