KR20020081640A - Silicone composition and electrically conductive silicone adhesive formed therefrom - Google Patents

Abstract

PURPOSE: Provided are an addition-hardening silicon composition comprising electrically conductive fillers and predetermined concentration of organopolysiloxane resin, and an adhesive produced from the same. CONSTITUTION: The composition comprises (A) 10-50 parts by weight of polydiorganosiloxane of formula 1(wherein, the polydiorganosiloxane contains average 2 or more alkenyl groups per molecule); (B) 50-90 parts by weight of organopolysiloxane resin consisting of R23SiO1/2 siloxane unit(wherein each of R2 is individually alkyl or alkenyl) and SiO4/2 siloxane unit(wherein molecular ratio of R23SiO1/2 siloxane unit to Si4/2 siloxane unit is 0.65-1.9, and the resin contains average 3-30 mol% of alkenyl group), wherein the sum of (A) and (B) is 100 parts by weight; (C) organohydrogen polysiloxane having average 2 or more silicon-bonded hydrogen per molecule, wherein amount of the organohydrogen polysiloxane(C) is sufficient to harden the composition; (D) sufficient amount of electrically conductive fillers to provide an electric conductivity to the composition(wherein the fillers comprise a particle having at least exterior surface formed from metal selected from the group consisting of silver, gold, platinum, palladium, and alloy thereof); and (E) catalytic amount of hydrosilylation catalyst. Formula 1: F13SiO(R12SiO)nSiR13(wherein each of R1 is independently monovalent aliphatic hydrocarbon group or monovalent aliphatic hydrocarbon halide group, and n is a value, which allows the polydiorganosiloxane to have a viscosity of 0.1-200 Pa.s at 25 deg.C).

Description

Silicone composition and electrically conductive silicone adhesive formed therefrom

The present invention relates to silicone compositions, and more particularly, to addition curable silicone compositions containing electrically conductive fillers and organopolysiloxane resins of particular concentration. The invention also relates to an electrically conductive silicone adhesive made from the composition.

Silicone adhesives are useful in a variety of applications because of their unique properties including high thermal stability, good moisture resistance, excellent flexibility, high ionic purity, low alpha particle release and good adhesion to various substrates. Silicone adhesives, for example, are widely used in the assembly of automotive parts, toys, electronic circuits and keyboards.

Addition curable silicone compositions comprising polydiorganosiloxanes, organohydrogenpolysiloxanes, electrically conductive fillers and hydrosilylation catalysts are known in the art. For example, US Pat. No. 5,075,038 to Cole et al. Has at least 5% silicon atoms bound to phenyl radicals, at least 5% vinyl radicals, or at least 5 mol% phenyl and vinyl radicals together. Silicone polymer (A) (such polymer is curable through addition reaction with silicon hydride in the presence of a platinum catalyst); And 12.5-50 vol.% Of the total composition, wherein the electrically conductive silicone composition comprises particle (s) (B) having an outer surface of silver, wherein the composition is free of carbon black and comprises 1 × 10 ⁻² ohms. It has an electrical resistivity of less than -cm (Ω · cm), and this electrical resistivity is stable to thermal aging. However, Cole et al. Do not teach particular combinations of the organopolysiloxanes and polymers of the invention.

In US Pat. No. 5,227,093 to Kohl et al. Teaches improved curable organosiloxane compositions exhibiting electrical conductivity in a cured form, the composition comprising organopolysiloxanes containing at least two alkenyl radicals per molecule, per molecule Organohydrogensiloxanes containing on average two or more silicon-bonded hydrogen atoms, products obtained by homogeneously combining finely divided silver particles and platinum containing catalysts in an amount sufficient to provide electrical conductivity to the cured material; Improvements include the presence of one or more esterified fatty acid coatings on the surface of the silver particles. However, Cole et al. Do not teach particular combinations of the organopolysiloxane resins and polymers of the present invention.

European Patent Publication No. 0 653 463 to Mine et al., 450 parts by weight of silver powder; 1) dimethylvinylsiloxy terminated dimethylpolysiloxane and 2) essentially (CH ₃ ) ₃ SiO _1/2 units, (CH ₂ = CH) (CH ₃ ) ₂ SiO _1/2 units and SiO _4/2 units 100 parts by weight of a mixture containing a silicone resin; 1 part by weight of trimethylsiloxy terminated methylhydrogensiloxane; 10 parts by weight of hydrophobic fumed silica; 500 ppm phenylbutynol, based on the total amount of the composition; Curing catalyst; And an electrically conductive silicone rubber composition prepared by homogeneously blending 7 parts by weight of an adhesion promoting organosilicon compound (Example 1). However, Mine et al. Do not teach organopolysiloxanes of specific concentrations of the invention.

Okami US Pat. No. 5,384,075 discloses organopolysiloxanes (A) having a volume resistivity of 107 Pa · cm or less, two or more alkenyl groups in the molecule, and a viscosity at 25 ° C. of 100 to 200,000 cSt. ), An organohydrogenpolysiloxane (B) having two or more silicon-bonded hydrogen atoms in a molecule, a platinum group metal catalyst (C), an organic group and an alkoxy group containing an epoxy group containing one or more silicon-bonded hydrogen atoms in the molecule Organopolysiloxane compositions comprising an organosilicon compound (D) and an electrically conductive filler (E) in which at least one member selected from the group consisting of are bonded to silicon atoms are described. Okami also refers to organopolysiloxane resins as optional components. Okami, however, does not teach organopolysiloxane resins of a particular concentration of the invention.

Silicone adhesives prepared from this composition exhibit a wide range of electrical properties, but there is a continuing need for silicone adhesives with improved electrical performance.

The inventors have found that silicone compositions containing electrically conductive fillers and specific concentrations of organopolysiloxane resins cured to produce adhesives with unexpectedly excellent electrical properties, contact resistance and volume resistivity. In particular, the present invention

10 to 50 parts by weight of polydiorganosiloxane (A), wherein the polydiorganosiloxane contains on average two or more alkenyl groups per molecule,

Organopolysiloxane resin (B) consisting of R ² ₃ SiO _1/2 siloxane units (where each R ² is independently alkyl or alkenyl) and SiO _4/2 siloxane units (where R ² ₃ SiO _{1 /} 50 to 90 parts by weight, wherein the molar ratio of ₂ siloxane units to SiO _4/2 siloxane units is 0.65 to 1.9 (wherein the total amount of components (A) and (B) is 100 parts by weight),

Organohydrogenpolysiloxane (C) having an average of at least two silicon-bonded hydrogen atoms per molecule in sufficient amount to cure the composition,

An electrically conductive filler (D) in an amount sufficient to provide electrical conductivity to the composition, wherein the filler comprises particles having an outer surface of at least a metal selected from the group consisting of silver, gold, platinum, palladium and alloys thereof. ) And

A silicone composition comprising a catalytic amount of hydrosilylation catalyst (E):

R ¹ ₃ SiO (R ¹ ₂ SiO) _n SiR ¹ ₃

In Formula 1 above,

Each R ¹ is independently a monovalent aliphatic hydrocarbon group or a monovalent halogenated aliphatic hydrocarbon group,

n is a value such that the polydiorganosiloxane has a viscosity of 0.1 to 200 Pa · s at 25 ° C.

The present invention also relates to an electrically conductive silicone adhesive comprising the reaction product of the composition.

The present invention also provides a multi-part silicone composition comprising components (A) to (E) in two or more parts, provided that neither component (A) nor component (B) is a component. It does not exist in the same part as (C) and component (E).

The silicone composition of the present invention has many advantages, including good flowability, low volatile organic compound (VOC) content, and adjustable curability. In addition, the silicone composition of the present invention is cured to produce a silicone adhesive having excellent adhesion and unexpectedly excellent electrical properties.

The silicone composition of the present invention is useful for making electrically conductive silicone adhesives. The silicone adhesive of the present invention has many uses, including die attach adhesives, solder substitutes and electrically conductive coatings and gaskets.

Component (A) of the present invention, also referred to herein as "polymer," is also one or more polydiorganosiloxanes having Formula 1, wherein the polydiorganosiloxane contains on average two or more alkenyl groups per molecule.

Formula 1

R ¹ ₃ SiO (R ¹ ₂ SiO) _n SiR ¹ ₃

In Formula 1 above,

Each R ¹ is independently a monovalent aliphatic hydrocarbon group or a monovalent halogenated aliphatic hydrocarbon group,

n is a value such that the polydiorganosiloxane has a viscosity of 0.1 to 200 Pa · s at 25 ° C.

The structure of the polydiorganosiloxane is generally linear, but it may contain some branching due to the presence of trifunctional siloxane units.

Alkenyl groups represented by R ¹ generally have 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms. Preferably, the alkenyl group is vinyl. Alkenyl groups in the polydiorganosiloxane may be located at the terminal, side positions, or both at the terminal and side positions. Monovalent aliphatic hydrocarbon groups and monovalent aliphatic halogenated hydrocarbon groups, except for alkenyl, represented by R ¹ , generally have from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms. Acyclic aliphatic hydrocarbons and halogenated hydrocarbon groups having three or more carbon atoms have a branched or unbranched structure.

Examples of monovalent aliphatic hydrocarbon groups include alkyl (eg, methyl, ethyl, propyl, pentyl, octyl, undecyl and octadecyl); Cycloalkyl (eg cyclohexyl); And alkenyl such as vinyl, allyl, butenyl and hexenyl. Examples of monovalent aliphatic halogenated hydrocarbon groups include 3,3,3-trifluoropropyl and 3-chloropropyl. Preferably at least 50%, more preferably at least 80% of the organic groups represented by R ¹ are methyl.

The viscosity of the polydiorganosiloxane at 25 ° C. varies depending on molecular weight and structure, and is generally 0.1 to 200 Pa · s, preferably 1 to 100 Pa · s.

Examples of polydiorganosiloxanes useful in the present invention include:

ViMe ₂ SiO (Me ₂ SiO) _n SiMe ₂ Vi, ViMe ₂ SiO (Me ₂ SiO) _0.98n (MeViSiO) _0.02n SiMe ₂ Vi and Me ₃ SiO (Me ₂ SiO) _0.95n (MeViSiO) _0.05n SiMe ₃ ( Where Me and Vi are methyl and vinyl, respectively, and n is as defined above). Preferred polydiorganosiloxanes are dimethylvinylsiloxane terminated polydimethylsiloxanes. Particular examples of preferred polydiorganosiloxanes are dimethylvinylsiloxy terminated polydimethylsiloxanes having a viscosity of 45 to 65 Pa · s at 25 ° C.

Component (A) may be a single polydiorganosiloxane or a mixture comprising two or more polydiorganosiloxanes differing in at least one of the following properties: structure, viscosity, average molecular weight, siloxane units and sequence.

The concentration of component (A) in the silicone composition of the present invention is generally 10 to 50 parts by weight, preferably 20 to 40 parts by weight, per 100 parts by weight of the mixed component (A) and component (B).

Methods of preparing the polydiorganosiloxanes of the present invention, such as hydrolysis and condensation of organohalosilanes or equilibration of cyclic polydiorganosiloxanes, are well known in the art.

Component (B) of the present invention, also referred to herein as "resin," consists of R ² ₃ SiO _1/2 siloxane units and SiO _4/2 siloxane units, wherein each R ² is independently alkyl or alkenyl. At least one organopolysiloxane resin. In addition, the organopolysiloxane resin may contain small amounts of monoorganosiloxane and diorganosiloxane units. The alkyl group represented by R ² generally has 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, pentyl, hexyl and cyclohexyl. Alkenyl groups represented by R ² generally have 2 to 6 carbon atoms. Examples of alkenyl groups include vinyl, allyl, butenyl and hexenyl. Preferably, the alkyl group is methyl and the alkenyl group is vinyl.

The molar ratio of R ² ₃ SiO _1/2 siloxane units (M units) to SiO _4/2 siloxane units (Q units) in the organopolysiloxane resin was determined by ²⁹ Si nuclear magnetic resonance ( ²⁹ Si NMR) spectroscopy. As is generally 0.65 to 1.9, preferably 0.9 to 1.8. The M / Q ratio represents the total number of M units to the total number of Q units in the organopolysiloxane resin and includes the contributions from the neopentamer present, which will be described below.

Component (B) contains HOSiO _3/2 units (TOH units), which is responsible for the silicon bound hydroxyl content of the organopolysiloxane resin. As measured by ²⁹ SiNMR spectroscopy, the silicon-bound hydroxyl content of component (B) is generally less than 2% by weight, preferably less than 1% by weight, based on the total amount of resin.

Component (B) may also contain small amounts of low molecular weight materials substantially consisting of neopentamer organopolysiloxanes of the formula (R ₂ SiO) ₄ Si, the latter being incorporated in methods such as Daut et al. It is a byproduct in the preparation of the following resin.

Organopolysiloxane resins generally contain an average of 3 to 30 mol%, preferably 5 to 15 mol% of alkenyl groups. As used herein, mol% of alkenyl groups in a resin is defined as the ratio of the number of moles of alkenyl-containing siloxane units in the resin multiplied by 100 to the total moles of siloxane units in the resin. If the resin contains less than 3 mol% alkenyl groups, the silicone adhesive tends to be soft and tacky. If the resin contains at least 30 mol% alkenyl groups, the silicone adhesive tends to be hard and brittle. In addition, when the mol% of alkenyl groups in the resin are outside the stated range, the electrical properties, contact resistance and volume resistivity of the adhesive are significantly degraded during thermal cycling.

A preferred organopolysiloxane resin is _{CH 2 = CH (CH 3)} 2 SiO 1/2 units, (CH ₃₎ a resin comprising SiO _1/2 units and SiO _4/2 units _3, wherein for the SiO _4/2 units The molar ratio of mixed CH ₂ = CH (CH ₃ ) ₂ SiO _1/2 units and (CH ₃ ) ₃ SiO _1/2 units is 1.8 and the resin has a viscosity of 2.1 × 10 ⁻⁴ m ² / s at 25 ° C. And the resin contains 15 mol% (5.6 wt%) of vinyl groups.

Component (B) may be a single organopolysiloxane resin or a mixture comprising two or more organopolysiloxane resins that differ in at least one of the following properties: monofunctional (M) siloxane units, M / Q ratios, average molecular weight, hydro Roxyl content and alkenyl content.

The concentration of component (B) in the silicone composition of the invention is important for the properties of the cured silicone adhesive, in particular for contact resistance and volume resistivity. The concentration of component (B) is 50 to 90 parts by weight, preferably 55 to 80 parts by weight, per 100 parts by weight of the mixed component (A) and component (B). When the concentration of component (B) is less than 50 parts by weight, the contact resistance and volume resistivity of the silicone adhesive are relatively high. When the concentration of component (B) is 90 parts by weight or more, the silicone adhesive tends to be hard and brittle, and exhibits poor resistance to thermal cycling. In the latter case, the adhesive breaks during thermal cycling, causing mechanical and / or electrical failures. In addition, since the M / Q ratio of the organopolysiloxane resin is reduced to the range of 0.65 to 1.9, it is understood that it may be necessary to reduce the concentration of the resin to the above range to obtain a silicone adhesive having satisfactory resistance to thermal cycling.

The organopolysiloxane resin of the present invention can be prepared by methods well known in the art. Preferably, the resin is prepared by treating the resin copolymer prepared by silica hydrosol capping methods such as dow with one or more alkenyl containing end blocking reagents. Doubt's method is described in US Pat. No. 2,676,182.

In simple terms, the method of Dow et al. Reacts silica hydrosol with hydrolyzable triorganosilane (eg trimethylchlorosilane), siloxane (eg hexamethyldisiloxane) or mixtures thereof under acidic conditions, with M units and Q units Recovering a copolymer having; The copolymer obtained generally contains from 2 to 5% by weight of hydroxyl groups.

Generally, resins of the present invention containing less than 2% by weight of silicon-bonded hydroxyl groups contain an amount of alkenyl containing ends sufficient to provide 3 to 30 mol% of alkenyl groups in the product, such as dow, and in the final product. It can be prepared by reacting a mixture of blockers or alkenyl containing end blockers and end blockers without aliphatic unsaturation. Examples of endblockers include, but are not limited to, silazanes, siloxanes, and silanes. Suitable end blockers are known in the art and are exemplified in US Pat. Nos. 4,584,355, 4,591,622, 4,585,836. Single end blockers or mixtures of such reagents can be used to prepare the organopolysiloxane resins of the invention.

Component (C) of the invention, also referred to herein as a "crosslinker", comprises at least one organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule and at most one silicon-bonded hydrogen atom per silicon atom. to be. In general, crosslinking occurs when the sum of the average number of alkenyl groups per molecule in the mixed component (A) and the component (B) and the average number of silicon-bonded hydrogen atoms in the component (C) is 4 or more. I understand. The silicon-bonded hydrogen atoms in the organohydrogenpolysiloxane may be located at the terminal position, the side position, or both at the terminal and side position.

Organohydrogenpolysiloxanes may be homopolymers or copolymers. The structure of the organohydrogenpolysiloxane may be linear, branched or cyclic. Examples of siloxane units that may be present in organohydrogenpolysiloxanes include HR ³ ₂ SiO _1/2 , HSiO _3/2 , R ³ ₃ SiO _1/2 , HR ³ SiO _2/2 , R ³ ₂ SiO _2/2 , R ³ SiO _3/2 and SiO _4/2 units. Each R ³ in the above formula is an independently monovalent aliphatic hydrocarbon or monovalent halogenated hydrocarbon group without aliphatic unsaturation, as defined and exemplified above for component (A). Preferably, at least 50% of the organic groups in the organohydrogenpolysiloxane are methyl.

Preferred organohydrogenpolysiloxanes are organohydrogenpolysiloxane resins consisting of H (CH ₃ ) ₂ SiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units, wherein the resin is about 1.0 Containing by weight of silicon-bonded hydrogen atoms, the viscosity of which is 2.4 × 10 ⁻⁵ m ² / s.

Component (C) can be a single organohydrogenpolysiloxane or a mixture comprising two or more organohydrogenpolysiloxanes differing in at least one of the following properties: structure, average molecular weight, viscosity, siloxane units and sequence.

The concentration of component (C) in the silicone composition of the present invention is sufficient to cure the composition. The exact amount of component (C) depends on the degree of cure desired, which is generally the number of moles of silicon-bonded hydrogen atoms in component (C) versus the number of moles of alkenyl groups present in the mixed components (A) and (B) Increases as the ratio increases. In general, the concentration of component (C) is sufficient to provide 0.5 to 3 silicon bonded hydrogen atoms per one alkenyl group in mixed component (A) and component (B). Preferably, the concentration of component (C) is sufficient to provide 1 to 2 silicon bonded hydrogen atoms per one alkenyl group in mixed component (A) and component (B).

Methods of preparing the organohydrogenpolysiloxanes of the present invention (eg hydrolysis and condensation of suitable organohalosilanes) are well known in the art.

In order to ensure the compatibility of components (A), (B) and (C), the main organic groups in each component are preferably identical. Preferably this group is methyl.

Component (D) of the present invention is at least one electrically conductive filler comprising particles having an outer surface consisting of at least a metal selected from the group consisting of silver, gold, platinum and alloys thereof. Fillers comprising particles of silver, gold, platinum, palladium and alloys thereof are generally in the form of powders or flakes with an average particle size of 0.5-20 μm. Fillers comprising particles having only external surfaces consisting of silver, gold, platinum, palladium and alloys thereof generally have an average particle size of 15 to 100 μm. The core of such particles may be any material, electrical conductor or insulator, which supports the surface of the metal above and does not adversely affect the electrical properties of the silicone adhesive. Examples of such materials include copper, solid glass, hollow glass, mica, nickel and ceramic fibers.

In the case of electrically conductive fillers comprising metal particles in the form of flakes, the surface of the particles may be applied with a lubricant (eg fatty acid or fatty acid ester). Such lubricants are generally introduced during the milling process used to make flakes from metal powder to produce flakes from the metal powder to prevent the powder from cold welding or forming large aggregates. Even when the flakes are washed with a solvent after milling, certain lubricants can remain chemisorbed on the surface of the metal.

The electrically conductive filler of the present invention also includes fillers prepared by treating the surface of the particles with one or more organosilicon compounds. Suitable organosilicon compounds include those commonly used for treating silica fillers, for example organochlorosilanes, organosiloxanes, organodisilazanes, organoalkoxysilanes.

Component (D) may be a single electrically conductive filler as mentioned above or a mixture of two or more such fillers having different one or more of the following properties: composition, surface area, surface treatment, particle size and particle shape.

Preferably, the electrically conductive filler of the invention comprises particles of silver, more preferably particles of silver in the form of flakes. Particularly preferred electrically conductive fillers are silver flakes sold under the trade name RA-127 (Chemmet Corporation). The median particle size of the filler is 3.9 μm, the surface area is 0.87 m ² / g, the apparent density is 1.55 g / cm ³ , and the processing density is 2.8 g / cm ³ .

The concentration of component (D) in the silicone composition of the present invention is sufficient to provide electrical conductivity to the composition. In general, the concentration of component (D) causes the composition to have a volume resistivity of less than 1 Pa · cm. The exact concentration of component (D) depends on the desired electrical properties, the surface area of the filler, the density of the filler, the shape of the filler particles, the surface treatment of the filler and the properties of the other components in the silicone composition. The concentration of component (D) is from 15 to 100% by volume, preferably from 15 to 50% by volume, based on the total volume of the silicone composition. If the concentration of component (D) is less than 15% by volume, the silicone adhesive does not exhibit significant electrical conductivity. If the concentration of component (D) is at least 100% by volume, the silicone adhesive does not exhibit substantially improved conductivity.

Methods of making electrically conductive fillers suitable for use in the silicone compositions of the present invention are well known in the art; Many of these fillers are commercially available. For example, silver, gold, platinum or palladium or alloys thereof are generally produced by chemical precipitation, electrolyte adhesion or cement cementation. In addition, flakes of such metals are generally prepared by grinding or milling metal powders in the presence of lubricants (such as fatty acids or fatty acid esters). Particles having only one or more outer surfaces of the metal are generally prepared by metallizing suitable core materials using methods such as electrolyte deposition, electroless deposition or vacuum deposition.

As mentioned above, the electrically conductive filler of the present invention may be a filler prepared by treating the surface of the particles with one or more organosilicon compounds. In this case, the particles can be treated before mixing with the other components of the silicone composition, or the particles can be treated in situ during the preparation of the silicone composition.

Component (E) of the present invention is a hydrosilylation catalyst that promotes the addition reaction of component (A) and component (B) with component (C). Hydrosilylation catalysts are well known hydrosilylation catalysts comprising platinum group metals, platinum group metal containing compounds or microencapsulated platinum group metal containing catalysts. Platinum group metals include platinum, rhodium, ruthenium, palladium, osmium and iridium. Preferably, the platinum group metal is platinum in terms of its activity in the hydrosilylation reaction.

Preferred hydrosilylation catalysts include complexes of the chloroplatinic acid and certain vinyl containing organosiloxanes mentioned by Willing in US Pat. No. 3,419,593. Preferred catalysts of this kind are the reaction products of chloroplatinic acid and 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane.

Particularly preferred hydrosilylation catalysts are microencapsulated platinum group metal containing catalysts comprising platinum group metals encapsulated in thermoplastic resins. Compositions containing microencapsulated hydrosilylation catalysts are stable under ambient conditions for long periods of time, typically months or more, but cure relatively rapidly at temperatures above the melting or softening point of the thermoplastic resin (s).

The thermoplastic resin may be a resin that is insoluble and impermeable to the platinum group metal containing catalyst and is also insoluble in the silicone composition. Thermoplastic resins generally have a softening point of about 40 to about 250 ° C.

As used above, the terms "insoluble" and "impermeable" mean that the amount of thermoplastic resin dissolved in the catalyst and / or silicone composition and the amount of catalyst diffused through the thermoplastic film former during storage are insufficient to cure the composition. do.

Examples of suitable thermoplastics include vinyl polymers such as polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, and copolymers of vinyl chloride and vinylidene chloride; Polyacrylates such as polymethacrylates; Cellulose derivatives such as cellulose ethers, esters and ether-esters; Polyamides; Polyester; Silicone resins and polysilanes. Silicone resins are preferred thermoplastic resins in accordance with the present invention.

Preferred catalysts for the preparation of microencapsulated hydrosilylation catalysts are platinum catalysts such as chloroplatinic acid, alcohol modified chloroplatinic acid, platinum / olefin complexes, platinum / ketone complexes and platinum / vinylsiloxane complexes.

The average particle size of the microencapsulated catalyst is generally 1 to 500 μm, preferably 1 to 100 μm. The microencapsulated catalyst generally contains at least 0.01 weight percent platinum group metal containing catalyst.

Preferred microencapsulated hydrosilylation catalysts are platinum complexes of 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane formed from silicone resins consisting of 78 mol% monophenylsiloxane units and 22 mol% dimethylsiloxane units. Wherein the silicone resin has a glass transition temperature of 60 ° C. and a softening point of 90 ° C. The average particle size of the microencapsulated catalyst is 1.8 μm and the platinum content is 0.4 wt%.

Methods of preparing microencapsulated hydrosilylation catalysts are well known in the art. Examples of such methods include chemical methods such as interfacial polymerization and in situ polymerization; Physicochemical methods such as coacervation and emulsification / suspension cure; And physical mechanical methods such as spray drying.

Microencapsulated hydrosilylation catalysts and methods for their preparation are described in US Pat. No. 4,766,176 and references cited therein; And US Pat. No. 5,017,654.

The concentration of component (E) is sufficient to catalyze the addition reaction of component (A) and component (B) with component (C). Generally, the concentration of component (E) is 0.1 to 1000 ppm, preferably 1 to 500 ppm, more preferably 5 to 5, based on the combined weight of components (A), (B) and (C). It is sufficient to provide 150 ppm of platinum group metal. The cure rate is very slow below 0.1 ppm platinum group metal. By using 1000 ppm or more platinum group metal, the cure rate does not increase appreciably and is therefore uneconomical.

The mixture of component (A), component (B), component (C), component (D) and component (E) may begin to cure at ambient temperature. In order to obtain longer working times or longer "storage life", suitable inhibitors may be added to the silicone composition of the present invention under ambient conditions to delay or inhibit the activity of the catalyst. The platinum catalyst inhibitor delays the curing of the silicone composition of the present invention at ambient temperature but does not prevent the composition from curing at elevated temperatures. Suitable platinum catalyst inhibitors include many “ene-yne” systems such as 3-methyl-3-pentene-1-yne and 3,5-dimethyl-3-hexen-1-yne; Acetylene alcohols such as 3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl-1-cyclohexanol and 2-phenyl-3-butyn-2-ol; Maleates and fumarates (eg, the well-known dialkyl, dialkenyl and dialkoxyalkyl fumarates and maleates); And cyclovinylsiloxanes.

Acetylene-based alcohols constitute a preferred kind of inhibitor in the silicone composition of the present invention. In particular, 2-phenyl-3-butyn-2-ol is a preferred inhibitor according to the invention. Compositions containing these inhibitors generally require heating above 70 ° C. to cure in a substantial proportion.

The concentration of platinum catalyst inhibitor in the silicone composition of the present invention is sufficient to delay curing of the composition at ambient temperature without preventing or excessively prolonging the cure at elevated temperatures. This concentration varies widely depending on the specific inhibitor used, the nature and concentration of the hydrosilylation catalyst, and the nature of the organohydrogenpolysiloxane.

In certain cases, with an inhibitor concentration as low as 1 mole of inhibitor per mole of platinum group metal, satisfactory storage stability and cure rate are obtained. In other cases, inhibitor concentrations of up to 500 or more moles of inhibitor per mole of platinum group metal may be required. The optimal concentration for a particular inhibitor in a given silicone composition can be readily determined by routine experimentation.

Preferably, the silicone composition of the present invention comprises a substrate commonly used in the manufacture of electronic devices, such as silicon; Passivation coatings such as silicon dioxide and silicon nitride; Glass; Metals such as copper and gold; ceramic; And adhesion promoters that result in strong under coat adhesion of the silicone composition to organic resins such as polyimide. The adhesion promoter may be an adhesion promoter generally used in silicone compositions, as long as it does not adversely affect the physical properties of the silicone adhesive, especially the contact resistance and volume resistivity. The adhesion promoter may be a single adhesion promoter or a mixture of two or more different adhesion promoters.

The concentration of the adhesion promoter in the composition of the present invention is sufficient to adhere the composition to a substrate as recited above. The concentration can vary widely depending on the properties of the adhesion promoter, the type of substrate and the desired adhesive bond strength. The concentration of the adhesion promoter is generally 0.01 to 10 parts by weight based on the total amount of the composition. However, the optimum concentration of the adhesion promoter can be easily determined by routine experimentation.

Preferred adhesion promoters according to the invention are adhesion promoters prepared by mixing at least one polysiloxane having at least one silicon bonded alkenyl group and at least one silicon bonded hydroxyl group and at least one epoxy containing alkoxysilane per molecule. Polysiloxanes generally have less than 15 silicon atoms per molecule, preferably 3 to 15 silicon atoms per molecule. Alkenyl groups in polysiloxanes generally have 2 to 6 carbon atoms. Examples of alkenyl groups include vinyl, allyl and hexenyl. Preferably, the alkenyl group is vinyl. Silicon-bonded organic groups remaining in the polysiloxanes are independently selected from alkyl and phenyl. Alkyl groups generally have less than 7 carbon atoms. Suitable alkyl groups are exemplified by methyl, ethyl, propyl and butyl. Preferably, the alkyl group is methyl.

The silicon-bonded hydroxyl and silicon-bonded alkenyl groups in the polysiloxanes may be located at the terminal, side positions, or both at the terminal and side positions. The polysiloxanes can be homopolymers or copolymers. The structure of polysiloxanes is generally linear or branched. In polysiloxanes, the siloxane units are CH ₂ = CHSiO _3/2 , C ₆ H ₅ SiO _3/2 , R ⁴ (CH ₂ = CH) SiO _2/2 , R ⁴ (C ₆ H ₅ ) SiO _2/2 , (C ₆ H ₅ ) ₂ SiO _2/2 , (C ₆ H ₅ ) (CH ₂ = CH) SiO _2/2 , (HO) R ⁴ ₂ SiO _1/2 , (CH ₂ = CH) R ⁴ ₂ SiO _{1 / 2} and (HO) (C ₆ H ₅ ) R ⁴ SiO _1/2 , wherein R ⁴ is an alkyl group having less than 7 carbon atoms as exemplified above. Preferably, the polysiloxane is a hydroxyl terminated polydiorganosiloxane containing methylvinylsiloxane units. Such polysiloxanes and methods for their preparation are well known in the art.

Epoxy containing alkoxysilanes contain at least one epoxy containing organic group and at least one silicon bonded alkoxy group. The structure of an epoxy containing alkoxysilane is generally linear or branched. Alkoxy groups in epoxy containing alkoxysilanes generally have less than 5 carbon atoms and are exemplified by methoxy, ethoxy, propoxy and butoxy, where methoxy is a preferred alkoxy group. Preferably, the epoxy containing organic group is of formula , or Wherein each Y is independently an alkyl group having 1 or 2 carbon atoms, a is 0, 1 or 2, b and c are each 0 or 1, and R ⁵ is a divalent hydrocarbon group having 12 or less carbon atoms It is.

Preferably, R ⁵ is a saturated aliphatic hydrocarbon group, an arylene group and a divalent group of formula -R ⁶ (OR ⁶ ) _d OR ^6- , wherein R ⁶ is a divalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms , d is a value from 0 to 8).

The silicon-bonded organic groups remaining in the epoxy containing alkoxysilanes are independently selected from monovalent hydrocarbon groups of less than 7 carbon atoms and fluorinated alkyl groups of less than 7 carbon atoms. Monovalent hydrocarbon groups include alkyl (eg, methyl, ethyl, propyl and hexyl); Alkenyl such as vinyl and allyl; And aryl (eg phenyl). Examples of suitable fluorinated alkyl groups include 3,3,3-trifluoropropyl, β- (perfluoroethyl) ethyl and β- (perfluoropropyl) ethyl.

Preferably, the epoxy containing alkoxysilane is a monoepoxytrialkoxysilane. Particular examples of preferred epoxy containing alkoxysilanes are glycidoxypropyltrimethoxysilane. Methods of making such silanes are well known in the art.

The two components of the adhesion promoter can be mixed together directly and added to the composition of the present invention or added separately to the composition. In general, the relative amounts of polysiloxane and silane are adjusted to provide about 1 mole of silane per mole of silanol group in the polysiloxane. Types of prior adhesion promoters are described in US Pat. No. 4,087,585.

Preferably, the polysiloxane and epoxy containing alkoxysilane are mixed first and then added to the composition. More preferably, the polysiloxanes and silanes are reacted at elevated temperatures. Organopolysiloxanes and silanes are reacted using well known methods of reacting silanol-containing organosiloxanes with alkoxysilanes. The reaction is generally carried out in the presence of a basic catalyst. Examples of suitable catalysts include alkali metal hydroxides, alkali metal alkoxides and alkali metal silanoates. Preferably, the reaction is carried out using about 1 mole of silane per mole of silicon-bonded hydroxyl group in the organopolysiloxane. Organopolysiloxanes and silanes may be reacted in the absence of diluents or in the presence of an inert organic solvent such as toluene. The reaction is preferably carried out at elevated temperatures of 80 to 150 ° C.

Particularly preferred adhesion promoters according to the invention are organopentasiloxanes having the formula (2):

AMe ₂ Si (OMe ₂ Si) ₃ OSiR ⁷ _4-e (OR ⁷ ) _e-1

In Formula 2 above,

A is hydrogen or an aliphatic unsaturated monovalent hydrocarbon group,

R ⁷ is alkyl,

e is an integer from 2 to 4.

Examples of aliphatic unsaturated monovalent hydrocarbon groups represented by A include vinyl, allyl, butenyl, hexenyl and isopropenyl. Preferably, A is a hydrogen atom or a vinyl group in terms of the availability and cost of the starting material. The alkyl group represented by R ⁷ generally has 1 to 6, preferably 1 to 3 carbon atoms. Examples of suitable alkyl groups include methyl, ethyl, propyl, butyl, pentyl and hexenyl. Alkyl groups containing three or more carbon atoms may have a branched or unbranched structure. Preferably, R ⁷ is methyl or ethyl in terms of availability and cost of the starting material.

The organopentasiloxane is first reacted with hexamethylcyclotrisiloxane and an organosilane of formula AMe ₂ SiX to form a tetrasiloxane of formula AMe ₂ Si (OMe ₂ Si) ₃ X, where A is as defined above and X is halogen It can be produced by Tetrasiloxane is then hydrolyzed to produce α-hydroxytetrasiloxane of the formula AMe ₂ Si (OMe ₂ Si) ₃ OH, where A is as defined above. α-hydroxytetrasiloxane is reacted with an organosiloxane of the formula R ⁷ _4-e Si (OR ⁷ ) _e , wherein R ⁷ and e are as defined above.

Particular examples of organopentasiloxane according to the present invention include 1-vinyl-9,9,9-trimethoxyoctamethylpentasiloxane of the formula ViMe ₂ SiO (Me ₂ SiO) ₃ Si (OMe) ₃ , wherein Vi is Vinyl and Me is methyl). Such organopentasiloxane is particularly preferred for the silicone composition of the present invention comprising a microencapsulated hydrosilylation catalyst. Importantly, the organopentasiloxane does not dissolve the silicone resin in the microencapsulated catalyst under ambient conditions. In addition, organopentasiloxanes exhibit excellent adhesion to metals commonly used in the manufacture of electronic devices. Types of prior adhesion promoters are described in US Pat. No. 5,194,649.

The silicone composition of the present invention may further comprise an appropriate amount of solvent to lower the viscosity of the composition and to facilitate the preparation, handling and application of the composition. Examples of suitable solvents include saturated hydrocarbons having 1 to 20 carbon atoms; Aromatic hydrocarbons such as xylenes; Weapon spirits; Halo hydrocarbons; ester; Ketones; Silicone fluids such as linear, branched, and cyclic polydimethylsiloxanes; And mixtures of such solvents. Optimal concentrations of certain solvents in the silicone composition of the invention are readily determined by routine experimentation.

In general, the silicone compositions of the present invention also contain small amounts of additional components (e.g., antioxidants, pigments, stabilizers, precured silicone rubbers), as long as they do not adversely affect the physical properties of the silicone adhesive, in particular contact resistance and volume resistivity Powders and fillers).

The silicone composition of the present invention is a one-part composition comprising the components (A) to (E) as one part, or two or more liquids (A) to the component (A). component (A) or component (B) may be a multi-part composition which is not present in the same part as component (C) and component (E). For example, a multi-liquid silicone composition for producing a silicone adhesive may comprise a first part comprising part of component (A), part of component (B), part of component (D) and all of component (E). And a second part containing component (A), component (B) and the remainder of component (D) and all of component (C).

The one-component silicone compositions of the present invention are generally prepared by combining components (A) through (E) and optional components at ambient temperatures in the ratios mentioned, in the presence or absence of the solvents mentioned above. The order of addition of the many components is not critical, but when the silicone composition is used immediately, the hydrosilylation catalyst is preferably added last at a temperature below 30 ° C. to prevent premature curing of the composition. In addition, the multi-liquid silicone composition of the present invention can be prepared by combining the specific components indicated for each liquid.

Mixing is carried out batchwise or continuously by techniques known in the art (eg milling, compounding and stirring). The particular device is measured by the viscosity of the components and the viscosity of the final silicone composition.

The silicone composition of the present invention should be stored in a sealed container to prevent exposure to air and moisture. The one-component silicone compositions of the present invention can be stored for several weeks at room temperature without changing the properties of the cured silicone adhesive product. However, the shelf life of the one-component silicone composition of the present invention can be extended to several months by storing the mixture at a temperature of 0 ° C. or lower, preferably −30 to −20 ° C. The individual sealing packages of the above-mentioned multi-liquid silicone compositions can be stored for 6 months or more under ambient conditions, without degrading the performance of the composition prepared upon mixing.

The silicone composition of the present invention may be a metal such as aluminum, gold, silver, copper and iron, and alloys thereof; silicon; Fluorocarbon polymers such as polytetrafluoroethylene and polyvinylfluoride; Polyamides such as nylon; Polyimide; Polyester; ceramic; And a wide variety of solid substrates including glass. In addition, the silicone composition of the present invention may be applied to the substrate by any suitable means (eg spraying, syringe dispensing, screen or stencil printing or ink jet printing).

The silicone adhesive according to the invention comprises the reaction product of the silicone composition containing the above-mentioned components (A) to (E). The silicone composition of the present invention may be cured by heating at room temperature or at a temperature of 200 ° C. or lower, preferably 70 to 200 ° C., more preferably 125 to 175 ° C. for a suitable time. For example, the silicone composition of the present invention cures at 150 ° C. for less than 2 hours.

The silicone composition of the present invention has many advantages, including good flowability, low volatile organic compound (VOC) content, and adjustable curing. In addition, the silicone composition of the present invention is cured to produce silicone adhesives having good adhesion and unexpectedly good electrical properties.

With regard to flowability, the silicone composition of the present invention has the rheological properties required for many applications and is easily dispensed and applied using standard equipment.

In addition, the silicone compositions of the present invention that do not require a solvent for many applications have a very low VOC content. Consequently, the silicone composition of the present invention prevents the health, safety and environmental hazards associated with solvent containing silicone compositions. In addition, the solventless compositions of the invention generally shrink less than solvent containing silicone compositions during curing.

The silicone composition of the present invention cures rapidly at moderately elevated temperatures without producing detectable byproducts. The curing rate of the silicone composition can be conveniently controlled by adjusting the concentration of catalyst and / or any inhibitor.

In addition, the silicone compositions of the present invention are cured to produce silicone adhesives that are excellent in adhesion to a wide variety of materials including metals, glass, silicon, silicon dioxide, ceramics, polyesters, and polyimides.

Importantly, the silicone compositions of the present invention are cured to produce silicone adhesives with unexpectedly superior electrical properties, initial contact resistance, and volume resistivity compared to similar silicone compositions containing low concentration organopolysiloxane resins. In addition, silicone adhesives generally exhibit excellent retention of electrical properties during thermal cycling.

The silicone composition of the present invention is useful for the production of electrically conductive silicone adhesives. The silicone adhesive of the present invention has a variety of uses, including die attach adhesives, solder substitutes and electrically conductive coatings and gaskets.

Unless otherwise stated, all parts and percentages reported in the examples are by weight. The following methods and materials are used in the examples:

The contact resistance of the silicone adhesive is measured using a Keithley Instruments Model 580 μ-μM meter equipped with a 4-pole probe with spring loaded, gold plated chisel point tips. Contact resistance junctions are made by first plating two square copper bars (0.254 cm x 0.254 cm x 2.032 cm) with nickel flash and then with a minimum thickness of 0.00013 cm with Type II, grade C, hard gold. A small aliquot of the silicone composition is applied at approximately the center of the rod (vertical). The second bar is then oriented perpendicular to the first bar (vertically) using the center of each bar facing the silicone composition forming an interface between the other and the two bars. Finally, the criss-cross (+) fixture is cured in a ventilated oven at 150 ° C. for 2 hours. After the sample is cooled to room temperature, the initial contact resistance of the junction is measured. Further contact resistance measurements are made after the assembly is subjected to one and six weeks of continuous temperature cycling, as described below. The values reported in contact resistance, expressed in mΩ, represent the average of three measurements, each performed on identically prepared test specimens.

The volume resistivity of the silicone adhesive is measured using a Keithley Instruments Model 580 μ-μW meter equipped with a four-point probe with spring loaded, gold plated chisel tip. Test specimens are prepared by first placing two pieces of 3M Scotch tape on a glass microscope slide 0.25 cm apart to form a channel extending along the length of the slide. An aliquot of the silicone composition is placed over the channel at one end of the slide. The razor blade is then dragged in the composition and spread across the surface at an angle of 45 ° to the entire channel. The tape pieces are removed and the specimen is cured at 150 ° C. for 2 hours in a ventilated oven. After cooling the sample to room temperature, the voltage drop between the two internal probe tips at a suitable current is measured to obtain a resistance value in mPa. The initial volume resistivity of the adhesive is then calculated using the following equation:

In Equation 1 above,

V is the volume resistivity of mΩ-cm,

R is the resistance (mΩ) of the adhesive measured between two internal probe tips spaced 2.54 cm apart,

W is the width of the adhesive layer (cm),

T is the thickness of the adhesive layer (cm),

L is the length of the adhesive layer between the inner probes in cm (2.54 cm).

The thickness of the adhesive layer, typically about 0.005 cm, is measured using an Ames Model P3-500 thickness meter. The volume resistivity of the silicone adhesive is also measured after 1 and 6 weeks of continuous temperature cycling, as described below. Values reported in volume resistivity, expressed in m-cm units, represent the average of three measurements, each performed on identically prepared test specimens.

Silicone adhesive samples are subjected to continuous temperature cycling using a Thermotron HPS-16 temperature laboratory. During each cycle, the test specimens are maintained at -50 ° C for 10 minutes, heated to -50 to 150 ° C in 30 minutes, maintained at 150 ° C for 10 minutes, and cooled to 150 to -50 ° C in 30 minutes. .

Polymer A: Dimethylvinylsiloxy terminated polydimethylsiloxane having a viscosity of 45 to 65 Pa · s at 25 ° C.

Resin A: Organopolysiloxane resin consisting of CH ₂ ═CH (CH ₃ ) ₂ SiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units [here, for SiO _4/2 units The molar ratio of the mixed CH ₂ = CH (CH ₃ ) ₂ SiO _1/2 units and (CH ₃ ) ₃ SiO _1/2 units is 1.8, the viscosity of the resin is 2.1 × 10 ⁻⁴ m ² / s, and the resin Contains 15 mol% (5.6 wt%) of vinyl groups.

Resin B: A solution consisting of 73.1% by weight organopolysiloxane resin in xylene, wherein the resin is CH ₂ = CH (CH ₃ ) ₂ SiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 Unit, wherein the molar ratio of mixed CH ₂ = CH (CH ₃ ) ₂ SiO _1/2 units to (CH ₃ ) ₃ SiO _1/2 units to SiO _4/2 units is 0.9, and the weight average of the resin Molecular weight is 5,000, multidispersity is 2 and contains about 7 mol% (2.7 wt%) of vinyl groups.

Resin C: A solution consisting of 70.0% by weight organopolysiloxane resin in xylene, wherein the resin is CH ₂ = CH (CH ₃ ) ₂ SiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 Unit, wherein the molar ratio of mixed CH ₂ = CH (CH ₃ ) ₂ SiO _1/2 units to (CH ₃ ) ₃ SiO _1/2 units to SiO _4/2 units is 0.7, and the weight average of the resin Molecular weight is 22,000, multidispersity is 5 and contains about 5.5 mol% (1.8 wt%) of vinyl groups.

Crosslinker: Organohydrogenpolysiloxane consisting of H (CH ₃ ) ₂ SiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units, wherein the organohydrogenpolysiloxane is silicon-bonded Hydrogen atom at 1.0 weight%, the viscosity of which is 2.4 x 10 ^-5 m ² / s).

Adhesion Promoter: Organopentasiloxane of Formula ViMe ₂ SiO (Me ₂ SiO) ₃ Si (OMe) ₃

Adhesion Promoter / Inhibitor Combination: Mixture consisting of 97% by weight of ViMe ₂ SiO (Me ₂ SiO) ₃ Si (OMe) ₃ and 3% by weight of 2-phenyl-3-butyn-2-ol.

Filler: Silver flake sold under the trade name RA-127 (Chemmet Corporation). The median particle size of the filler is 3.9 μm, the surface area is 0.87 m ² / g, the apparent density is 1.55 g / cm ³ and the processing density is 2.8 g / cm ³ .

Catalyst A: 40% by weight of a complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and platinum dispersed in a thermoplastic silicone resin, wherein the resin is 78 mol% of monophenylsiloxane units and 22 mol% Consisting of dimethylsiloxane units, and the softening point of the resin is 80 to 90 캜); 55% by weight of polymer B, dimethylvinylsiloxy terminated polydimethylsiloxane (viscosity at 25 ° C., 2 Pa.s, vinyl content is 0.2% by weight) and 5% by weight of hexamethyldisilazane treated pyrolysis silica Mixture consisting of. The platinum content of the catalyst is 0.16% by weight.

Catalyst B: A dispersion of a platinum complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in Resin A, wherein the catalyst contains 0.54% by weight of platinum.

Example 1

8.10 parts by weight of catalyst A, 38.22 parts by weight of polymer, 5.11 parts by weight of adhesion promoter / inhibitor formulation, 7.29 parts by weight of adhesion promoter, 57.33 parts by weight of resin A and 583.2 parts (28% by volume) of filler were prepared in a 1 oz plastic cup do. The ingredients are blended for 26 seconds using an AM-501 Hauschild dental mixer. The mixture is then cooled to room temperature by immersing the cup in the water bath for about 5 minutes. The crosslinker (29.83 parts by weight) is added to the mixture and the above mentioned mixing and cooling process is repeated twice. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 1.

Example 2

A silicone composition is prepared using the method of Example 1 and components in the following concentrations: 8.60 parts of catalyst A, 19.05 parts of polymer, 5.42 parts of adhesion promoter / inhibitor blend, 7.75 parts of adhesion promoter, 76.22 parts of resin A 619.67 parts by weight (28 vol.%) Of filler and 37.88 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 1.

Comparative Example 1

A silicone composition was prepared using the method of Example 1, but Resin A was omitted, and the following concentrations of components were used: 6.57 parts by weight of catalyst A, 96.39 parts by weight of polymer, 4.14 parts by weight of adhesion promoter / inhibitor blend, adhesion promoter 5.92 parts by weight, 473.37 parts by weight of filler (28% by volume) and 5.33 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 1.

Comparative Example 2

A silicone composition is prepared using the method of Example 1 and components in the following concentrations: 7.59 parts by weight of catalyst A, 57.51 parts by weight of polymer, 4.78 parts by weight of adhesion promoter / inhibitor blend, 6.83 parts by weight of adhesion promoter, 38.32 parts by weight of resin A. 546.45 parts by weight (28 vol.%) Of filler and 21.58 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 1.

Comparative Example 3

Prepared using the method of Example 1, but omitting polymer A and using components in the following concentrations: 9.09 parts by weight of catalyst A, 5.73 parts by weight of adhesion promoter / inhibitor blend, 8.19 parts by weight of adhesion promoter, 95.00 weight of resin A Parts 655.20 parts by weight (28 vol.%) Of filler and 45.78 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 1.

Example ¹ part by weight of resin Contact resistance ² (mΩ) Initial 1 week 6 weeks Volume Reduction Rate ³ (mΩcm) Initial 1 Week 6 Weeks Example 1 57 11.87 76.38 6438.33 0.31 0.51 1.61 Example 2 76 6.45 11.28 95.34 0.20 0.24 0.53 Comparative Example 1 0 --- --- Comparative Example 2 38 164.67 44067- 0.98 2.62 30.68 Comparative Example 3 95 7.57 82.80 B 0.30 0.52 1.25

Parts by weight of resin per 100 parts by weight of mixed resin and polymer ¹ .

² B represents a fractured junction and − is a value exceeding 2 × 10 ⁸ mPa.

³ − is a value exceeding 1 × 10 ⁵ mPa · cm.

Example 3

A silicone composition was prepared by combining 2.13 parts by weight of catalyst B, 39.17 parts by weight of polymer, 80.35 parts by weight of resin B, 12.13 parts by weight of xylene, 518.81 parts by weight of filler (23.2% by volume) and 11.28 parts by weight of an adhesion promoter / inhibitor blend in a 1 oz plastic cup. do. The ingredients are blended using an AM-501 Hauschild dental mixer for about 26 seconds. The mixture is then cooled to room temperature by immersing the cup in the water bath for about 5 minutes. Crosslinking agent (18.35 parts by weight) is added to the mixture and the mixing and cooling processes mentioned above are repeated. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 2.

Example 4

A silicone composition is prepared using the method of Example 3 and the following concentrations of component: 2.20 parts by weight of catalyst B, 19.58 parts by weight of polymer, 107.04 parts by weight of resin B, 6.04 parts by weight of xylene, 536.55 parts by weight of filler (23.2% by volume) 11.67 parts by weight of adhesion promoter / inhibitor blend and 22.40 parts by weight of crosslinker. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 2.

Comparative Example 4

Using the method of Example 3 to prepare a silicone composition deviating from the scope of the present invention, wherein Resin B is omitted and is prepared using the components in the following concentrations: 1.91 parts by weight of catalyst B, 98.13 parts by weight of polymer, 30.32 of xylene Parts by weight, filler (23.2% by volume) 466.47 parts by weight, 10.14 parts by weight of adhesion promoter / inhibitor formulation and 6.41 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 2.

Comparative Example 5

A silicone composition was prepared using the method of Example 3 and the components in the following concentrations: 2.06 parts by weight of catalyst B, 58.84 parts by weight of polymer, 53.58 parts by weight of resin B, 18.19 parts by weight of xylene, 501.88 parts by weight of filler (23.2% by volume). , 10.91 parts by weight of adhesion promoter / inhibitor formulation and 14.43 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 2.

Comparative Example 6

A silicone composition is prepared using the method of Example 3, but polymer A and additional xylenes are omitted and prepared using the components in the following concentrations: 2.27 parts by weight of catalyst B, 133.79 parts by weight of resin B, filler (23.2 vol. %) 554.02 parts by weight, 12.05 parts by weight of adhesion promoter / inhibitor formulation and 26.39 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 2.

Example ¹ part by weight of resin Contact resistance ² (mΩ) Initial 1 week 6 weeks Volume Reduction Rate ³ (mΩcm) Initial 1 Week 6 Weeks Example 3 61 0.66 0.50 0.96 0.73 0.91 2.42 Example 4 80 0.67 0.76 2.97 1.00 1.93 6.53 Comparative Example 4 2 --- --- Comparative Example 5 41 1.99 2.11 14.21 120.80-- Comparative Example 6 100 2.03 B B -C C

¹ parts by weight of resin per 100 parts by weight of mixed resin and polymer.

² B represents a fractured junction and − is a value exceeding 2 × 10 ⁸ mPa.

³ C represents a cracked adhesive layer, and − is a value exceeding 1 × 10 ⁵ mPa · cm.

Example 5

A silicone composition was prepared by combining 2.05 parts by weight of catalyst B, 39.20 parts by weight of polymer, 84.03 parts by weight of resin C, 14.90 parts by weight of xylene, 500.94 parts by weight of filler (22.4% by volume) and 10.89 parts by weight of an adhesion promoter / inhibitor blend in a 1 oz plastic cup. do. The ingredients are blended using an AM-501 Hauschild dental mixer for about 26 seconds. The mixture is then cooled to room temperature by immersing the cup in the water bath for about 5 minutes. Crosslinking agent (14.28 parts by weight) is added to the mixture and the mixing and cooling processes mentioned above are repeated. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 3.

Example 6

A silicone composition was prepared using the method of Example 5 and the components in the following concentrations: 2.10 parts by weight of catalyst B, 19.58 parts by weight of polymer, 111.96 parts by weight of resin C, 7.29 parts by weight of xylene, 511.84 parts by weight of filler (22.4% by volume). 11.13 parts by weight of adhesion promoter / inhibitor formulation and 16.76 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 3.

Comparative Example 7

A silicone composition is prepared using the method of Example 5, except that Resin C is omitted and is prepared using the components in the following concentrations: 1.91 parts by weight of catalyst B, 98.13 parts by weight of polymer, 30.32 parts by weight of xylene, filler (23.2) Volume%) 466.47 parts by weight, 10.14 parts by weight of adhesion promoter / inhibitor formulation and 6.41 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 3.

Comparative Example 8

A silicone composition was prepared using the method of Example 5 and the components in the following concentrations: 2.00 parts by weight of catalyst B, 58.84 parts by weight of polymer, 56.02 parts by weight of resin C, 22.39 parts by weight of xylene, 489.30 parts by weight of filler (22.4% by volume). , 10.65 parts by weight of adhesion promoter / inhibitor formulation and 11.62 parts by weight of crosslinking agent. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 3.

Comparative Example 9

Using the method of Example 5, except that polymer A and additional xylenes are omitted, the silicone composition is prepared using the following concentrations of components: 2.15 parts by weight of catalyst B, 139.88 parts by weight of resin C, silver filler (22.4 vol. %) 523.90 parts, 11.40 parts of the adhesion promoter / inhibitor combination and 19.52 parts of the crosslinker. The contact resistance and volume resistivity of the cured silicone adhesive are shown in Table 3.

Example Resin / Polymer (W / W) Contact resistance ² (mΩ) Initial 1 week 6 weeks Volume Reduction Rate ³ (mΩcm) Initial 1 Week 6 Weeks Example 5 61 0.66 3.15 7.14 23.97-- Example 6 80 0.64 B B 23.86-- Comparative Example 7 2 --- --- Comparative Example 8 41 1.89 11.42 218.14 --- Comparative Example 9 100 0.72 B B 19.75--

¹ parts by weight of resin per 100 parts by weight of mixed resin and polymer.

² B represents a fractured junction and − is a value exceeding 2 × 10 ⁸ mPa.

³ − is a value exceeding 1 × 10 ⁵ mPa · cm.

According to the present invention, silicone compositions containing electrically conductive fillers and specific concentrations of organopolysiloxane resins can be cured to produce adhesives with unexpectedly good electrical properties, contact resistance and volume resistivity.

Claims (7)

10 to 50 parts by weight of polydiorganosiloxane (A), wherein the polydiorganosiloxane contains on average two or more alkenyl groups per molecule, R ² ₃ SiO _1/2 siloxane units (where each R ² is independently alkyl, alkenyl, or Al) and the organopolysiloxane resin (B) consisting of SiO _4/2 siloxane units (where SiO _4/2 siloxane units, The molar ratio of R ² ₃ SiO _1/2 siloxane units to is from 0.65 to 1.9 and the resin contains an average of from 3 to 30 mol% of alkenyl groups, from 50 to 90 parts by weight, wherein component (A) and component The total amount of (B) is 100 parts by weight), Organohydrogenpolysiloxane (C) having an average of at least two silicon-bonded hydrogen atoms per molecule in sufficient amount to cure the composition, An electrically conductive filler (D) in an amount sufficient to provide electrical conductivity to the composition, wherein the filler comprises particles having an outer surface of at least a metal selected from the group consisting of silver, gold, platinum, palladium and alloys thereof. ) And Silicone composition containing a catalytic amount of hydrosilylation catalyst (E). Formula 1 R ¹ ₃ SiO (R ¹ ₂ SiO) _n SiR ¹ ₃ In Formula 1 above, Each R ¹ is independently a monovalent aliphatic hydrocarbon group or a monovalent halogenated aliphatic hydrocarbon group, n is a value such that the polydiorganosiloxane has a viscosity of 0.1 to 200 Pa · s at 25 ° C. The silicone composition according to claim 1, wherein the concentration of the organopolysiloxane resin is 55 to 80 parts by weight per 100 parts by weight of the mixed component (A) and component (B). The silicone composition of claim 1 wherein the filler comprises silver particles in the form of flakes. The silicone composition of claim 1 wherein the composition further comprises an adhesion promoter of formula (2). Formula 2 AMe ₂ Si (OMe ₂ Si) ₃ OSiR ⁷ _4-e (OR ⁷ ) _e-1 In Formula 2 above, A is hydrogen or an aliphatic unsaturated monovalent hydrocarbon group, R ⁷ is alkyl, e is an integer from 2 to 4. Silicone adhesive comprising the reaction product of the composition according to claim 1. Silicone adhesive comprising the reaction product of the composition according to claim 3. 10 to 50 parts by weight of polydiorganosiloxane (A), wherein the polydiorganosiloxane contains on average two or more alkenyl groups per molecule, Organopolysiloxane resin (B) consisting essentially of R ² ₃ SiO _1/2 siloxane units, wherein each R ² is independently alkyl or alkenyl, and SiO _4/2 siloxane units, wherein SiO _4/2 The molar ratio of R ² ₃ SiO _1/2 siloxane units to siloxane units is 0.65 to 1.9 and the resin contains an average of about 3 to 30 mol% alkenyl groups) from 50 to 90 parts by weight, wherein component (A) And the total amount of component (B) is 100 parts by weight), Organohydrogenpolysiloxane (C) having an average of at least two silicon-bonded hydrogen atoms per molecule in sufficient amount to cure the composition, An electrically conductive filler (D) in an amount sufficient to provide electrical conductivity to the composition, wherein the filler comprises particles having an outer surface of at least a metal selected from the group consisting of silver, gold, platinum, palladium and alloys thereof. ) And Multi-part silicone compositions comprising a catalytic amount of hydrosilylation catalyst (E), provided that neither component (A) nor component (B) is identical to component (C) and component (E) Does not exist in). Formula 1 R ¹ ₃ SiO (R ¹ ₂ SiO) _n SiR ¹ ₃ In Formula 1 above, Each R ¹ is independently a monovalent aliphatic hydrocarbon group or a monovalent halogenated aliphatic hydrocarbon group, n is a value such that the polydiorganosiloxane has a viscosity of 0.1 to 200 Pa · s at 25 ° C.