JP7811965B2 - Silicone composition and polysiloxane compound - Google Patents

Description

The present invention relates to a polysiloxane compound and a silicone composition containing the same.

As semiconductor devices become increasingly high-capacity and dense, they are required to have high heat dissipation capabilities. Therefore, in recent years, thermally conductive materials known as thermal interface materials have been placed between semiconductor devices, such as IC chips, which are heat-generating components, and heat sinks or housings, which are cooling components, to efficiently dissipate heat generated by the semiconductor devices to the outside.

One type of thermal interface material is a thermally conductive silicone composition, which is made by mixing a thermally conductive filler with a silicone resin, due to its excellent heat resistance and rubber properties. Thermally conductive silicone compositions are generally curable, and their properties are effectively demonstrated by curing after being applied or placed in the desired location.

The higher the filling rate of thermally conductive filler in a thermally conductive silicone composition, the better the heat dissipation properties, so it is preferable to fill as much as possible. However, increasing the filling rate can cause the thermally conductive silicone composition to become too hard. In particular, the hardness of a cured product of a thermally conductive silicone composition tends to continue to increase even after curing is complete if it is left at high temperatures for an extended period of time. Excessive hardness in a thermally conductive silicone composition makes it more susceptible to cracking. If cracks occur in the thermally conductive silicone composition, gaps will form, which may prevent the desired heat dissipation properties from being achieved.

Patent Document 1 therefore provides a curable organopolysiloxane composition that contains a high filling rate of thermally conductive filler and is able to suppress an increase in hardness even when aged for long periods under high-temperature conditions. The curable organopolysiloxane composition of Patent Document 1 contains an organopolysiloxane and at least one selected from fatty acids, fatty acid esters, and fatty acid metal salts.

WO2022/215510

However, with the recent trend toward even higher capacity semiconductor devices, more reliable heat dissipation has become important, and as a result, there is a demand for organopolysiloxane compositions that can further suppress increases in hardness compared to the organopolysiloxane composition of Patent Document 1.

The present invention aims to provide a silicone composition containing a filler and a silicone resin that can suppress an increase in hardness when left at high temperatures for an extended period of time, and a polysiloxane compound used therein.

To solve the above problems, the present invention includes the following inventions.

The present invention [1] comprises a silicone composition containing (A) a linear organopolysiloxane having one dicarboxylic acid metal salt structure at the end of its main chain, (B) a filler, and (C) a silicone resin.

The present invention [2] includes the silicone composition described in [1], in which the structure of the metal dicarboxylate is a group represented by the following formula (1) or (2):

(In formulas (1) and (2), M ^d+ represents an alkali metal ion or an alkaline earth metal ion.
a is an integer of 0 or more and 10 or less, b is an integer of 0 or more and 3 or less, and c is an integer of 0 or more and 3 or less.
d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal.
e is 2 when M is an alkali metal, and is 1 when M is an alkaline earth metal.
f is an integer of 0 to 10, g is an integer of 0 to 5, and h is an integer of 0 to 5.

The present invention [3] includes the silicone composition according to [1] or [2], in which the content of the filler in the silicone composition is 70% by mass or more.

The present invention [4] includes the silicone composition described in any one of [1] to [3], in which the filler is a thermally conductive filler.

The present invention [5] includes the silicone composition according to any one of [1] to [4], in which the silicone resin is a curable silicone resin.

The present invention [6] includes the silicone composition described in [5], in which the curable silicone resin contains an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane.

The present invention [7] includes a silicone cured product obtained by curing the silicone composition described in [5] or [6].

The present invention [8] includes an electronic component comprising a heat-generating component, a cooling component, and the silicone composition described in any one of [1] to [6] or the silicone cured product described in [7], which is placed in contact with the heat-generating component and the cooling component.

The present invention [9] includes a polysiloxane compound represented by the following formula (5):

(In formula (5), ^R1 represents a hydrocarbon group, ^R2 represents a hydrocarbon group, n is an integer of 1 or more and 100 or less, and A is a group represented by the following formula (1) or (2).)

(In formulas (1) and (2), M ^d+ represents an alkali metal ion or an alkaline earth metal ion.
a is an integer of 0 or more and 10 or less, b is an integer of 0 or more and 3 or less, and c is an integer of 0 or more and 3 or less.
d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal.
e is 2 when M is an alkali metal, and is 1 when M is an alkaline earth metal.
f is an integer of 0 to 10, g is an integer of 0 to 5, and h is an integer of 0 to 5.

The silicone composition and polysiloxane compound of the present invention can suppress an increase in hardness of the silicone composition when left at high temperatures for an extended period of time.

FIG. 1 is a schematic cross-sectional view of a semiconductor device according to the present invention. FIG. 2 shows the IR spectrum of the polysiloxane modified with succinic anhydride at one end prepared in Synthesis Example 1. FIG. 3 shows the IR spectrum of the polysiloxane modified with lithium succinate at one end prepared in Synthesis Example 1. FIG. 4 shows the IR spectrum of the polysiloxane modified with lithium succinate at one end prepared in Synthesis Example 2. FIG. 5 shows the IR spectrum of the polysiloxane modified with calcium succinate at one end prepared in Synthesis Example 3. FIG. 6 shows the IR spectrum of the one-terminated lithium monocarboxylate-modified polysiloxane prepared in Synthesis Example 5.

An example of an embodiment of the present invention will be described in detail below. However, the present invention is not limited to the embodiment described below, and can be modified and implemented as desired without departing from the spirit of the present invention.

The silicone composition of the present invention (hereinafter also referred to as "the composition") contains (A) a linear organopolysiloxane having one dicarboxylate metal salt structure at the end of its main chain (hereinafter also referred to as "the polysiloxane"), (B) a filler, (C) a silicone resin, and any other optional components. These are described below.

(A) The Present Polysiloxane The present polysiloxane is a linear organopolysiloxane having one dicarboxylate metal salt structure at one end of its main chain. In other words, the present polysiloxane is an organopolysiloxane having a dicarboxylate metal salt structure at one end.

The structure of a metal salt of dicarboxylic acid is a functional group having the main skeleton of a metal salt of dicarboxylic acid, specifically, a group in which one hydrogen atom has been removed from a metal salt of dicarboxylic acid.

Examples of metal dicarboxylates include malonate, succinate, glutarate, adipate, pimelate, suberate, sebacate, phthalate, 2,2'-biphenyldicarboxylate, 1,4-cyclohexanedicarboxylate, and bicyclo[2.2.1]heptane-2,3-dicarboxylate. Preferred examples include malonate, succinate, glutarate, and bicyclo[2.2.1]heptane-2,3-dicarboxylate.

Examples of metal salts that make up the dicarboxylic acid metal salt include alkali metal salts such as lithium salt, sodium salt, and potassium salt; and alkaline earth metal salts such as magnesium salt, calcium salt, and barium salt. Alkali metal salts are preferred, and lithium salts are more preferred.

The structure of the dicarboxylic acid metal salt preferably includes a group represented by the following formula (1) or (2):

In the formulas (1) and (2), M ^d+ represents an alkali metal ion or an alkaline earth metal ion.

a is, for example, an integer of 0 or more and 10 or less. Preferably, it is 1 or more, and preferably 8 or less, and more preferably 5 or less.

b is, for example, an integer of 0 or greater and 3 or less. Preferably, it is 1 or greater and 2 or less.

c is, for example, an integer of 0 or greater and 3 or less. Preferably, it is 1 or greater and 2 or less.

d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal.

e is 2 when M is an alkali metal, and 1 when M is an alkaline earth metal.

f is, for example, an integer greater than or equal to 0 and less than or equal to 10. Preferably, it is greater than or equal to 1 and less than or equal to 8, and more preferably less than or equal to 5.

g is, for example, an integer of 0 or more and 5 or less. Preferably, it is 1 or more and 3 or less.

For example, h is an integer greater than or equal to 0 and less than or equal to 5. Preferably, it is greater than or equal to 1 and less than or equal to 3.

Among the groups represented by formula (1), the group represented by formula (3) below is more preferred, and among the groups represented by formula (2), the group represented by formula (4) below is more preferred. A particularly preferred structure of the dicarboxylic acid metal salt is the group represented by formula (3).

In formulas (3) and (4), M' is an alkali metal. Examples of alkali metals include lithium, sodium, and potassium, with lithium being preferred.

The linear organopolysiloxane portion of this polysiloxane has a siloxane bond (—O—Si—) in the main chain and an organic group in the side chain. Preferably, the side chain does not have a siloxane bond. The organic group is, for example, a hydrocarbon group, and is preferably ^R1, which will be described later.

The other terminal of the present polysiloxane may be, for example, a hydrocarbon group, a hydrogen atom, a vinyl group, an acryloyl group, a methacryloyl group, a hydroxyl group, etc. These are preferably ^R2 , which will be described later.

A specific example of such a polysiloxane is preferably a polysiloxane compound represented by the following formula (5):

^R1 is, for example, a hydrocarbon group, and preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Examples of the hydrocarbon group for ^R1 include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n-octyl, and decyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl, tolyl, and xylyl; aralkyl groups such as benzyl and phenethyl; and fluoroalkyl groups such as trifluoropropyl. Preferably, an alkyl group is used, and more preferably, a methyl group or an ethyl group is used. Multiple ^R1s may be the same or different.

^R2 is, for example, a hydrocarbon group, a hydrogen atom, a vinyl group, an acryloyl group, a methacryloyl group, a hydroxyl group, or the like, preferably a hydrocarbon group. These hydrocarbon groups may be substituted with a halogen atom or the like. The hydrocarbon group has, for example, 1 or more, preferably 3 or more carbon atoms, and for example, 20 or less, preferably 10 or less. Examples of the hydrocarbon group for ^R2 include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, a decyl group, a dodecyl group, and an octadecyl group; cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group; aryl groups such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group; aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group; and fluoroalkyl groups such as a trifluoropropyl group. Preferably, an alkyl group is used, and more preferably, an n-butyl group or a methyl group is used.

n is, for example, a number between 1 and 100. It is preferably 10 or greater, more preferably 20 or greater, and preferably 90 or less, more preferably 60 or less, and even more preferably 30 or less. When n is at or above the lower limit, the compatibility between the polysiloxane and the silicone resin matrix resin is improved, allowing the polysiloxane to perform its functions more effectively. When n is at or below the upper limit, the fluidity of the composition is excellent.

A is a group represented by the above formula (1) or (2), preferably a group represented by formula (1), and more preferably a group represented by formula (3).

Among the polysiloxane compounds represented by formula (5), polysiloxane compounds represented by the following formulas (6) and (7) are more preferred, and polysiloxane compounds represented by formula (6) are even more preferred.

The content of the present polysiloxane is, for example, 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and for example, 100 parts by mass or less, preferably 80 parts by mass or less, more preferably 50 parts by mass or less, per 100 parts by mass of the silicone resin described below. The content of the present polysiloxane in the present composition is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, and for example, 10% by mass or less, preferably 5% by mass or less.

This polysiloxane can be produced, for example, by (1) a ring-opening polymerization process of a cyclic siloxane, (2) a hydrosilylation process, and (3) an ion exchange process.

(1) In the ring-opening polymerization step of cyclic siloxanes, cyclic siloxanes are subjected to ring-opening polymerization to obtain linear polysiloxanes. Known methods can be used for the ring-opening polymerization of cyclic siloxanes. Preferably, anionic ring-opening polymerization is carried out using an alkyllithium compound as the initiator and a silane hydride halide as the terminator. This results in linear single-terminated Si-H polysiloxanes with Si-H bonded to one end and an alkyl group bonded to the other end.

Examples of cyclic siloxane raw materials include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and decamethylcyclohexasiloxane. Examples of alkyllithium compounds include methyllithium, n-butyllithium, sec-butyllithium, and tert-butyllithium. Examples of silane hydride halides include chlorodimethylsilane. The reaction conditions and reagents for anionic ring-opening polymerization can be determined according to known methods.

(2) In the hydrosilylation step, a dicarboxylic acid or dicarboxylic anhydride is bonded to the linear polysiloxane obtained in the ring-opening polymerization step using a hydrosilylation reaction. Specifically, a single-terminated Si-H polysiloxane is added to a dicarboxylic acid or dicarboxylic anhydride having an unsaturated bond. This results in a single-terminated dicarboxylic acid-modified polysiloxane with a dicarboxylic acid or dicarboxylic anhydride bonded to one end and an alkyl group bonded to the other end.

Examples of dicarboxylic acids or dicarboxylic anhydrides having unsaturated bonds include allyl succinic anhydride and 5-norbornene-2,3-dicarboxylic anhydride.

The hydrosilylation reaction preferably uses a hydrosilylation catalyst. Examples of the hydrosilylation catalyst include the same hydrosilylation catalysts as those described below as (C3). The hydrosilylation reaction conditions, reagents, etc. may be determined in accordance with known methods.

(3) In the ion exchange step, the product obtained in the hydrosilylation step is subjected to ion exchange. Specifically, the H of the carboxylic acid in the one-terminal dicarboxylic acid-modified polysiloxane is exchanged with a metal ion. This results in a one-terminal dicarboxylic acid metal salt-modified polysiloxane (i.e., the present polysiloxane) in which a dicarboxylic acid metal salt is bonded to one terminal and an alkyl group is bonded to the other terminal.

In the ion exchange process, if the one-terminal dicarboxylic acid-modified polysiloxane is an acid anhydride, it is preferable to simultaneously carry out hydrolysis. Specifically, the one-terminal dicarboxylic acid-modified polysiloxane, a lower fatty acid metal salt, and water are reacted under heating. Examples of lower fatty acid metal salts include acetate salts and propionate salts. Examples of metal salts that make up the lower fatty acid metal salt include alkali metal salts such as lithium salts, sodium salts, and potassium salts; and alkaline earth metal salts such as magnesium salts, calcium salts, and barium salts. These metal salts may also be hydrated. The heating temperature is, for example, 50°C or higher and 150°C or lower. Other reaction conditions, reagents, etc. may be determined according to known methods.

In addition, as a method other than the (3) ion exchange process, a method of carrying out a neutralization reaction using an alkali metal or alkaline earth metal hydroxide, such as lithium hydroxide, can also be used.

(B) Filler Examples of fillers include inorganic fillers and organic fillers. Preferably, inorganic fillers are used, and more preferably, thermally conductive fillers are used. This provides excellent thermal conductivity and makes the material suitable for use in thermal interface materials. In addition, it is possible to reliably suppress an increase in hardness due to interactions between the filler and the silicone resin.

Thermal conductive fillers are inorganic particles with good thermal conductivity, such as alumina, zinc oxide, magnesium oxide, titanium oxide, silicon nitride, aluminum nitride, boron nitride, aluminum hydroxide, magnesium hydroxide, silicon carbide, calcium carbonate, barium sulfate, talc, silica, diamond, aluminum, silver, and copper. These may be used alone or in combination of two or more. From the viewpoint of excellent thermal conductivity, alumina, silicon nitride, aluminum nitride, and boron nitride are preferred, and from the viewpoint of ease of handling, alumina and aluminum nitride are preferred.

The shape of the filler may be, for example, spherical, such as a perfect sphere, a polyhedral sphere, or an ellipsoidal sphere; plate-like, needle-like, crushed, aggregated, or irregular, with spherical being preferred.

The average particle size of the filler is, for example, 0.01 μm or more, preferably 0.1 μm or more, and, for example, 500 μm or less, preferably 200 μm or less. In the present invention, the average particle size refers to the particle size at 50% volumetric similarity (D50) on the particle size distribution curve determined by laser diffraction.

The present composition preferably uses multiple fillers with different average particle sizes. For example, at least two of the following are used: a large-diameter filler with an average particle size of 50 μm or more; a medium-diameter filler with an average particle size of 10 μm or more but less than 50 μm; a small-diameter filler with an average particle size of 1 μm or more but less than 10 μm; and a microfiller with an average particle size of less than 1 μm. Preferably, three or more of the above fillers are used, and more preferably, all four of the above fillers are used. This ensures an improved filler loading rate in the composition. Therefore, when a thermally conductive filler is used, the thermal conductivity of the composition can be further improved.

The specific surface area of the entire filler is, for example, 0.1 ^{m 2} /g or more and 10 m ² /g or less. The specific surface area is measured by the BET method. Furthermore, the cumulative pore volume of pores with a pore diameter of 0.5 μm or less in the entire thermally conductive filler is, for example, 0.1 mL or less. The pore diameter is calculated from the maximum diameter distribution measured with a mercury porosimeter.

The filler may be treated with a surface treatment agent. Examples of surface treatment agents include known treatment agents such as silane coupling agents.

The filler content (filling rate) in the composition is, by mass, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 85% by mass or more, and even more preferably 92% by mass or more, and for example, 99% by mass or less, preferably 97% by mass or less, and more preferably 95% by mass or less. Furthermore, by volume, for example, 50% by volume or more, preferably 65% by volume or more, more preferably 80% by volume or more, and for example, 99% by volume or less, preferably 97% by volume or less, and more preferably 95% by volume or less. The higher the filler content, the easier it is to increase the thermal conductivity of the resin composition. The lower the filler content, the easier it is to increase the fluidity of the resin composition. From the viewpoint of the balance between thermal conductivity and fluidity, it is preferable to set the filler content at or above the above lower limit and at or below the above upper limit. In particular, when the filler content is 70% by mass or more, the filler is generally present in an overcrowded position relative to the silicone resin, which facilitates interaction between the filler and the silicone resin and can lead to increased hardness over the long term; however, this composition can more reliably suppress this increase in hardness.

(C) Silicone Resin The silicone resin is a polymer having a siloxane bond in the main skeleton, and may be either a curable silicone resin or a non-curable silicone resin, but is preferably a curable silicone resin. This provides excellent fluidity and workability, making it suitable for use in thermal interface materials and the like.

Examples of curable silicone resins include addition reaction type silicone resins and condensation reaction type silicone resins. Addition reaction type silicone resins are preferred.

When the silicone resin is an addition reaction type silicone resin, the silicone resin contains, for example, both (C1) an alkenyl group-containing organopolysiloxane and (C2) a hydrosilyl group-containing organopolysiloxane. In this case, the silicone resin may optionally contain (C3) a hydrosilylation catalyst to induce the addition reaction. In this composition, the catalyst required for the curing reaction is contained as part of the silicone resin.

(C1) an alkenyl group-containing organopolysiloxane,
The alkenyl-group-containing organopolysiloxane is the base resin of the silicone resin and contains alkenyl groups. Examples of the alkenyl groups include vinyl groups, allyl groups, and butenyl groups, with vinyl groups being preferred. The alkenyl groups may be bonded to the molecular chain terminals or to side chains, but from the standpoint of reactivity, etc., they are preferably bonded to both molecular chain terminals.

The alkenyl group-containing organopolysiloxane may be linear, branched, or cyclic, but is preferably linear. Furthermore, the alkenyl group-containing organopolysiloxane may be used alone or in combination with two or more types.

Preferably, the alkenyl group-containing organopolysiloxane is a polysiloxane represented by the following formula (8):

^R3 is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of the hydrocarbon group include the same groups as those exemplified for ^R1 . Preferably, an alkyl group is used, and more preferably, a methyl group or an ethyl group is used. Multiple ^R3s may be the same or different from each other.

^R4 is an alkenyl group as described above. Multiple ^R4s may be the same or different.

m is, for example, a number greater than or equal to 0 and less than or equal to 10,000. Preferably, it is greater than or equal to 10 and less than or equal to 1,000.

The viscosity of the alkenyl group-containing organopolysiloxane at 23°C is, for example, 1 mPa·s or more, preferably 10 mPa·s or more, and for example, 100,000 mPa·s or less, preferably 1,000 mPa·s or less. By setting the viscosity within this range, a composition having the desired physical properties can be obtained with good workability. The viscosity can be measured using an E-type viscometer. Specifically, using a conical plate with a diameter of 40 mm and a cone angle of 2.0°, and using a Peltier plate, measurements can be taken from a shear rate of 0.1 to 100 s ^-1 while maintaining a temperature condition of 25°C, and the value at which the viscosity reaches a steady value can be regarded as the viscosity to be measured.

(C2) Hydrosilyl Group-Containing Organopolysiloxane The hydrosilyl group-containing organopolysiloxane functions as a crosslinking agent that crosslinks base resins together, and contains hydrosilyl groups (—Si—H). The hydrosilyl groups may be bonded to the molecular chain terminals or to side chains.

The hydrosilyl group-containing organopolysiloxane may be linear, branched, or cyclic, but is preferably linear. Furthermore, one type of hydrosilyl group-containing organopolysiloxane may be used alone, or two or more types may be used in combination.

Preferably, the hydrosilyl group-containing organopolysiloxane is a polysiloxane represented by the following formula (9):

^R5 is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of the hydrocarbon group include the same groups as those exemplified for ^R1 . Preferably, an alkyl group is used, and more preferably, a methyl group or an ethyl group is used. Multiple ^R5s may be the same or different from each other.

p and q are each, for example, a number greater than or equal to 2 and less than or equal to 100. Preferably, they are greater than or equal to 10 and less than or equal to 50.

The viscosity of the hydrosilyl group-containing organopolysiloxane at 23°C is, for example, 1 mPa·s or more, preferably 10 mPa·s or more, and, for example, 100,000 mPa·s or less, preferably 1,000 mPa·s or less. By keeping the viscosity within this range, a composition with the desired physical properties can be obtained with good workability.

The mixing ratio by mass of the (C1) alkenyl group-containing organopolysiloxane and the (C2) hydrosilyl group-containing organopolysiloxane is determined appropriately depending on the composition ratio of the alkenyl groups and hydrosilyl groups. For example, the hydrosilyl group-containing organopolysiloxane may be added in an amount of, for example, 1 part by mass or more and 100 parts by mass or less, and preferably 10 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of the alkenyl group-containing organopolysiloxane.

(C3) Hydrosilylation catalyst The hydrosilylation catalyst is a metal catalyst used in the hydrosilylation reaction. Examples of such catalysts include platinum group metals such as platinum, rhodium, ruthenium, and palladium, and compounds thereof. Examples of platinum group metal compounds include platinum dichloride, platinum dibromide, platinum tetrachloride, chloroplatinic acid, alcohol-modified chloroplatinic acid, Karsted's catalyst (a complex of platinum and vinylsiloxane), sodium chloroplatinate, potassium chloroplatinate, bisacetylacetonatoplatinum, tetrakis(triphenylphosphine)palladium, and chlorotris(triphenylphosphine)rhodium. These may be used alone or in combination of two or more.

The content of the hydrosilylation catalyst may be any amount necessary for the curing reaction. For example, it may be, for example, 0.01 part by mass or more, preferably 0.1 part by mass or more, and for example, 1 part by mass or less, preferably 0.5 part by mass or less, per 100 parts by mass of the total of (C1) and (C2).

The content of silicone resin in this composition is, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 5% by mass or more, and for example, 45% by mass or less, preferably 25% by mass or less, more preferably 10% by mass or less.

(D) Other Components The present composition preferably contains an alkoxysilyl group-containing compound from the viewpoints of increasing the affinity with the filler and the silicone resin and improving the flowability of the present composition.

Examples of the alkoxysilyl group contained in the alkoxysilyl group-containing compound include trialkoxysilyl groups such as trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, and triphenoxysilyl; dimethoxysilyl groups such as dimethoxymethylsilyl and diethoxymethylsilyl; and monoalkoxysilyl groups such as methoxydimethylsilyl and ethoxydimethylsilyl. Trialkoxysilyl groups are preferred, and trimethoxysilyl and triethoxysilyl groups are more preferred.

The alkoxysilyl group-containing compound preferably includes a polysiloxane represented by the following formula (10):

^R6 is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of the hydrocarbon group include the same groups as those exemplified for ^R1 . Preferably, an alkyl group is used, and more preferably, a methyl group or an ethyl group is used. Multiple ^R6s may be the same or different from each other.

^R7 is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 20 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of the hydrocarbon group include the same groups as those exemplified for ^R2 . Preferably, an alkyl group is used, and more preferably, an n-butyl group or a methyl group is used.

^R8 is an alkoxysilyl group, as described above.

k is, for example, a number greater than or equal to 0 and less than or equal to 100. Preferably, it is greater than or equal to 10 and less than or equal to 50.

j is, for example, a number greater than or equal to 0 and less than or equal to 10. Preferably, it is greater than or equal to 1, and preferably less than or equal to 8, and more preferably less than or equal to 5.

The content of the alkoxysilyl group-containing compound in the composition is, for example, 0.1% by mass or more, preferably 0.3% by mass or more, and for example, 3% by mass or less, preferably 1% by mass or less.

When the silicone resin is a curable silicone resin, the composition preferably contains a reaction inhibitor to inhibit the curing reaction of the silicone resin. This inhibits the curing reaction of the composition before use, improving storage stability. It also inhibits a rapid curing reaction during use, improving the ease of placement of the composition.

Examples of reaction inhibitors include acetylene alcohol, benzotriazole, triphenylphosphine, and diallyl maleate, with acetylene alcohol being preferred. Examples of acetylene alcohols include ethynyl-1-cyclohexanol and 2-methyl-3-butyn-2-ol. These may be used alone or in combination of two or more.

The content of the reaction inhibitor in this composition is, for example, 0.01% by mass or more, preferably 0.03% by mass or more, and, for example, 1% by mass or less, preferably 0.1% by mass or less.

The composition may contain other components in addition to those described above, provided that the effects of the present invention are not impaired. Examples of other components include flame retardants, antifoaming agents, leveling agents, antioxidants, and colorants.

The composition can be prepared by mixing (A) the polysiloxane, (B) the filler, (C) the silicone resin (e.g., (C1) an alkenyl group-containing organopolysiloxane, (C2) a hydrosilyl group-containing organopolysiloxane, and (C3) a hydrosilylation catalyst), and, if necessary, other components, using a known method. For example, these components may be mixed simultaneously or in any suitable order.

The mixing can be carried out by a known method using a known mixing device such as a blender or mixer. If necessary, the mixing may be carried out in a heated atmosphere or an inert gas atmosphere.

The silicone composition of the present invention can suppress the hardness increase of the present invention and its cured product when left at high temperatures (e.g., 100°C or higher and 200°C or lower) for long periods of time (e.g., 500 hours or higher and 1500 hours or lower). Furthermore, the composition has excellent fluidity, making it easy to apply and use. The hardness increase suppression effect of the present invention is believed to be due to the following mechanism, but the present invention is not limited to this mechanism. Generally, in conventional silicone compositions highly filled with fillers such as thermally conductive fillers, a chemical interaction occurs between hydroxyl groups on the filler surface and hydrosilyl groups on the silicone resin. This reaction proceeds over a long period of time at high temperatures, resulting in a continuous increase in the hardness of the composition. In contrast, the present composition contains the present polysiloxane having a dicarboxylate metal salt structure. It is believed that the dicarboxylate metal salt portion interacts with the filler surface before the silicone resin does, inhibiting the interaction between the filler and the silicone resin. Furthermore, because this polysiloxane has a polysiloxane structure, it is similar to the silicone resin matrix resin and has good compatibility with the silicone resin. This allows it to exist uniformly in the silicone resin, and it is thought to inhibit the above-mentioned interactions without phase separation.

The composition may be in any form, but is preferably liquid, as long as it contains (A) the polysiloxane, (B) a filler, and (C) a silicone resin. When the composition is liquid, it may be a one-part or two-part composition. When the composition is a two-part composition (first and second parts), the combination of components in the first and second parts is not limited. For example, when the composition is an addition reaction silicone composition containing an addition reaction silicone resin, the composition preferably contains (A) the polysiloxane, (B) a filler, (C1) an alkenyl group-containing organopolysiloxane, (C2) a hydrosilyl group-containing organopolysiloxane, (C3) a hydrosilylation catalyst, and (D) a reaction inhibitor. In this case, it is preferable that the first or second parts do not simultaneously contain (C1) the alkenyl group-containing organopolysiloxane and (C2) the hydrosilyl group-containing organopolysiloxane. For example, a combination of the first agent: (A) (B) (C1) (C3) and the second agent: (C2) (D), or a combination of the first agent: (A) (B) (C1) (C3) and the second agent: (A) (B) (C1) (C2) (D), etc. may be used.

The use of this composition is not limited and it can be used for a variety of purposes. However, when the composition contains a thermally conductive filler, it can be suitably used as a thermal interface material for efficiently dissipating heat generated from semiconductor devices to the outside. The composition may also be used as a thermally conductive grease, thermally conductive filler, thermally conductive sheet, thermally conductive adhesive, etc. Furthermore, the composition can also be used as part of the components of electrical and electronic devices, including semiconductor devices.

(electronic parts)
As an embodiment in which the present composition is used as a thermal interface material, a semiconductor device, which is an example of an electronic component, will be described below with reference to FIG.

The semiconductor device 1 shown in Figure 1 includes a printed wiring board 2, an IC chip 3 which is an example of a heat-generating component, a heat sink 4 which is an example of a cooling component, and a thermal interface material 5.

The thermal interface material 5 is disposed between the IC chip 3 and the heat sink 4 so as to be in contact with them. The thermal interface material 5 is formed from the present composition. In particular, when the present composition is a curable silicone composition containing a curable silicone resin, the thermal interface material 1 is preferably a cured silicone product obtained by curing the curable silicone composition. That is, it is preferable to place the uncured curable silicone composition between the IC chip 3 and the heat sink 4 and then cure it. This allows the composition to be disposed without any gaps between the IC chip 3 and the heat sink 4, allowing heat from the IC chip 3 to be more efficiently conducted to the heat sink 4. The curable silicone composition can be cured according to a known method, for example, by heating at a temperature of 80°C or higher and 200°C or lower.

Note that while Figure 1 illustrates an IC chip 3 as an example of a heat-generating component, various semiconductor devices such as power modules and transistors can also be used as heat-generating components. Although a heat sink 4 is illustrated as an example of a cooling component, a housing or the like can also be used as a cooling component.

The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

[Synthesis Example 1]
(Preparation of Si—H-Terminated Polysiloxane)
A reactor equipped with a rotor and a nitrogen-filled gas bag was charged with 66.7 g of hexamethylcyclotrisiloxane and 50 g of cyclohexane, after which 19.2 mL (1.57 mol/L) of a hexane solution of n-butyllithium was added dropwise and the mixture was stirred at 35°C for 2 hours. Next, 20 g of THF was added dropwise to this solution and the mixture was stirred for 21 hours. After that, 3.69 g of chlorodimethylsilane was added dropwise and the mixture was stirred for 2 hours. A 10% by weight aqueous solution of sodium bicarbonate was added to the resulting crude reaction liquid, causing it to separate into two layers, and the organic layer was washed with distilled water. This organic layer was dehydrated with magnesium sulfate, the solvent was removed using an evaporator, and the remaining volatile components were removed under conditions of 80°C and 100 Pa, yielding 60.0 g (85% yield) of the following single-terminated Si—H polysiloxane. The number of repeating units is an average value determined from ^1H -NMR.

The results of ¹ H-NMR measurement of the obtained Si—H-terminated polysiloxane are shown below.
¹ H-NMR (500 MHz, solvent: CDCl ₃ ) δ (ppm): 4.70 (1H, m, H-Si), 1.31 (4H, m, C-CH ₂ CH ₂ -C), 0.88 (3H, t, CH ₃ -C), 0.53 (2H, m, Si-CH ₂ ), 0.0-0.2 (144H, m, CH ₃ -Si).

(Preparation of one-terminal succinic anhydride-modified polysiloxane)
A reactor equipped with a Dimroth column and a thermometer was charged with 50.0 g of the above-mentioned single-terminated Si—H polysiloxane, 5.0 g of allylsuccinic anhydride, 50 ml of toluene, and 5.4 mg of a Pt catalyst (a 2% by mass xylene solution of a Pt 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex), and the mixture was stirred at 80°C for 18 hours. The resulting crude reaction liquid was heated to 120°C, and volatile components were removed under reduced pressure (100 Pa), yielding 51.0 g (95% yield) of the following single-terminated succinic anhydride-modified polysiloxane. The number of repeating units is an average value determined from ^1H -NMR.

The results of ¹ H-NMR measurement of the obtained polysiloxane modified with succinic anhydride at one end are shown below.
¹ H-NMR (500 MHz, solvent: CDCl ₃ ) δ (ppm): 3.10 (1H, m, CH-CO), 2.5-2.8 (2H, m, CH ₂ -CO), 1.3-1.8 (8H, m, Si-C-CH ₂ CH ₂ -C), 0.88 (3H, m, C-CH ₃ ), 0.56 (4H, m, Si-CH ₂ ), 0.0-0.2 (144H, m, CH ₃ -Si).

The IR (ATR) measurement results for the obtained polysiloxane modified with succinic anhydride at one end are shown below and in Figure 2. IR (cm ^-1 ): 2962 (C-H), 1865 (C=O), 1789 (C=O), 1257 (Si-CH ₃ ), 1012-1078 (Si-O)

(Preparation of one-terminated lithium succinate-modified polysiloxane)
10 g of the above-mentioned one-terminal succinic anhydride-modified polysiloxane, 0.67 g of lithium acetate, 50 mL of THF, and 1 mL of water were placed in a reactor equipped with a distillation apparatus and heated at 60°C for 2 hours. Subsequently, the temperature was raised to 80°C, and stirring was continued while distilling off the THF and by-product acetic acid. After the distillation stopped, 50 mL of toluene was added to the reactor and heated at 125°C, and the acetic acid was removed by azeotropy with toluene. After the distillation stopped, toluene was added again, and the mixture was heated at 125°C until the distillation stopped. Next, volatile components were removed at 120°C under reduced pressure (100 Pa), and the following gel-like one-terminal lithium succinate-modified polysiloxane was obtained.

The results of IR (ATR method) measurement of the obtained polysiloxane modified with lithium succinate at one end are shown below and in FIG.
IR (cm ^-1 ): 2962 (C-H), 1611 (C=O), 1572 (C=O), 1258 (Si-CH ₃ ), 1012-1078 (Si-O)

Figures 2 and 3 show that lithium carboxylate is produced, as the C=O stretching vibration shifts to the wavenumber associated with the metal carboxylate.

[Synthesis Example 2]
The following mono-terminal lithium succinate-modified polysiloxane was obtained in the same manner as in Synthesis Example 1, except that the amount of hexamethylcyclotrisiloxane charged was changed to 133.4 g.

The results of IR (ATR method) measurement of the above-mentioned polysiloxane modified with lithium succinate at one end are shown below and in FIG.
IR (cm ^-1 ): 2962 (C-H), 1611 (C=O), 1582 (C=O), 1258 (Si-CH ₃ ), 1012-1078 (Si-O)

[Synthesis Example 3]
The following mono-terminal calcium succinate-modified polysiloxane was obtained in the same manner as in Synthesis Example 1, except that lithium acetate was replaced with calcium acetate monohydrate.

The results of IR (ATR method) measurement of the above-mentioned polysiloxane modified with calcium succinate at one end are shown below and in FIG.
IR (cm ^-1 ): 2962 (C-H), 1604 (C=O), 1564 (C=O), 1258 (Si-CH ₃ ), 1012-1078 (Si-O)

[Synthesis Example 4]
A reaction vessel equipped with a reflux condenser was charged with 20 g of 10-undecylenic acid and 20 g of toluene and heated to 80°C. 10.9 g of hexamethyldisilazane was added dropwise to the mixture, and after the dropwise addition was completed, the mixture was heated at 80°C for an additional 3 hours. The mixture was heated to 100°C under reduced pressure to remove volatile components, yielding CH ₂ ═CH(CH ₂ ) _{8CO 2} SiMe ₃ (27.0 g, yield 97%). A flask equipped with a reflux condenser was charged with 6.37 g of the above silylated product, 50 g of the single-terminated Si—H polysiloxane prepared in [Synthesis Example 1], and 10 mg of Pt catalyst (a 2% by mass xylene solution of Pt complexed with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane), and the mixture was heated at 80°C for 2 hours. After cooling to room temperature, 10 g of methanol was added, and the mixture was stirred at room temperature for 12 hours. The mixture was heated to 160° C. under reduced pressure to remove volatile components, and then allowed to cool to room temperature to obtain the following mono-terminally monocarboxylic acid-modified polysiloxane (52.7 g, yield 98%).

[Synthesis Example 5]
A reactor equipped with a distillation apparatus was charged with 10 g of the one-terminal monocarboxylic acid-modified polysiloxane prepared in [Synthesis Example 4], 0.30 g of lithium acetate, 50 mL of THF, and 1 mL of water, and heated at 60°C for 2 hours. The temperature was then raised to 80°C, and the mixture was stirred while distilling off the THF and by-product acetic acid. After the distillation stopped, 50 mL of toluene was added to the reactor, and the mixture was heated at 125°C to remove the acetic acid by azeotropy with toluene. After the distillation stopped, toluene was added again, and the mixture was heated at 125°C until the distillation stopped. Next, volatile components were removed at 120°C under reduced pressure (100 Pa), and the following gel-like one-terminal lithium monocarboxylic acid-modified polysiloxane was obtained.

The results of IR (ATR method) measurement of the above-mentioned one-terminal lithium monocarboxylate-modified polysiloxane are shown below and in FIG.
IR (cm ^-1 ): 2962 (C-H), 1579 (C=O), 1560 (C=O), 1258 (Si-CH ₃ ), 1013-1078 (Si-O)

[Raw materials]
The following raw materials were used:
Aluminum nitride (D ₅₀ : 120 μm, manufactured by Tokuyama Corporation)
Aluminum nitride ( _D50 : 20 μm , manufactured by Tokuyama Corporation)
Aluminum nitride (D ₅₀ : 1 μm, manufactured by Tokuyama Corporation)
Alumina ( _D50 : 75 μm)
Alumina ( _D50 : 1.5 μm)
Alumina ( _D50 : 0.3 μm)
Vinyl group-containing organopolysiloxane (structure shown below, viscosity (23°C) 100 mPa·s)

Hydrosilyl group-containing organopolysiloxane (structure shown below, viscosity (23°C) 50 mPa·s)

- Hydrosilylation catalyst (platinum metal)
Alkoxysilyl group-containing polysiloxane (structure below (k=30), affinity agent)

Reaction inhibitor (ethynyl-1-cyclohexanol)
・Lithium stearate

[Examples 1 to 8]
A silicone resin mixture was obtained by mixing 2.41 parts by mass of a vinyl group-containing organopolysiloxane, 0.60 parts by mass of a hydrosilyl group-containing organopolysiloxane, 0.01 parts by mass of a hydrosilylation catalyst, and 0.03 parts by mass of ethynyl-1-cyclohexanol. Next, the raw materials were mixed in the proportions shown in Table 1 below to prepare the liquid silicone compositions of Examples 1 to 8. The numbers in the table indicate parts by mass.

[Comparative Examples 1 to 4]
Liquid silicone compositions of Comparative Examples 1 to 4 were prepared by mixing the raw materials according to the formulations shown in Table 1 below.

[Liquidity evaluation]
The fluidity of the silicone compositions of each Example and Comparative Example was evaluated as follows, and the results are shown in Table 1.
◯: When each silicone composition was poured into a 30 cc syringe and discharged from a 2 mm diameter nozzle, the amount discharged per minute was 25 g or more.
Δ: The discharge amount per minute was 15 g or more and less than 25 g.
x: The amount of discharge per minute was less than 15 g.

[Evaluation of initial hardness]
The silicone composition of each example and comparative example was heated at 100°C for 2 hours so that it would cure into a sheet having a thickness of 6 mm. The hardness of the resulting cured silicone product was measured using a rubber hardness tester (Durometer GS-721G, TYPE-E, manufactured by Teclock Corporation). The results are shown in Table 1.

[Evaluation of hardness after long-term heating test]
The silicone cured product was then heated at 150°C for 1000 hours, after which its hardness was measured. The difference (B-A) between the initial hardness A and the hardness B after the heating test was calculated. The results are shown in Table 1.

Table 1 shows that the silicone composition of this example has good fluidity, resulting in good workability during application and other processes. Furthermore, the silicone composition of this example shows a reduced change in hardness before and after testing compared to the silicone composition of the comparative example, which does not contain this polysiloxane, indicating that the increase in hardness is suppressed when left at high temperatures for long periods of time.

REFERENCE SIGNS LIST 1 Semiconductor device 2 Printed wiring board 3 Semiconductor chip 4 Heat sink 5 Present composition

Claims (5)

(A) a linear organopolysiloxane having one dicarboxylic acid metal salt structure at the end of its main chain;
(B) a filler;
(C) a curable silicone resin ,
The structure of the dicarboxylic acid metal salt is a group represented by the following formula (1) or (2):
The silicone composition, wherein the curable silicone resin contains an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane .
(In formulas (1) and (2), M ^d+ represents an alkali metal ion or an alkaline earth metal ion.
a is an integer of 0 or more and 10 or less, b is an integer of 0 or more and 3 or less, and c is an integer of 0 or more and 3 or less.
d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal.
e is 2 when M is an alkali metal, and is 1 when M is an alkaline earth metal.
f is an integer of 0 to 10, g is an integer of 0 to 5, and h is an integer of 0 to 5. The silicone composition according to claim 1, wherein the content of the filler in the silicone composition is 70% by mass or more. The silicone composition according to claim 1, wherein the filler is a thermally conductive filler. A cured silicone product obtained by curing the silicone composition according to claim 1 . A heat-generating member;
A cooling member;
An electronic component comprising the silicone composition according to any one of claims 1 to 3 or the silicone cured product according to claim 4 , which is placed so as to be in contact with the heat-generating component and the cooling component.