Organopolysiloxane prepolymer and cured article of said organopolysiloxane prepolymer

Abstract

Provided is an organopolysiloxane prepolymer that can provide a cured article having excellent heat resistance and adhesion. An organopolysiloxane prepolymer according to an embodiment of the present invention is a condensation product of: (A) a polydimethylsiloxane having silanol groups at both terminals; (B) at least one substance selected from the group consisting of silane oligomers having an alkoxy group, complete or partial hydrolysates of said silane oligomers, and condensation products of said oligomers; (C) at least one substance selected from the group consisting of tetramethoxysilane and tetraethoxysilane; and (D) a silane compound having a phenyl group.

Description

Organopolysiloxane prepolymer and cured body of said organopolysiloxane prepolymer

[0001] The present invention relates to organopolysiloxane prepolymers and cured products of said organopolysiloxane prepolymers.

[0002] Semiconductor encapsulants are used to protect semiconductor devices from light, heat, dust, and other microscopic particles, as well as from external impacts. Semiconductor encapsulants are required to have properties such as heat resistance, moisture resistance, impact resistance, and electrical insulation. Epoxy resins and urethane resins are known materials for semiconductor encapsulants (for example, Patent Documents 1 and 2).

[0003] Patent No. 7460025, Patent No. 7289568

[0004] Polyimide resins and liquid crystal polymers are known resins with low dielectric properties. However, because these do not adhere well, bonding materials are required, and sufficient heat resistance may not be obtained. Furthermore, it has been proposed to improve adhesion by adding condensation-type polydimethylsiloxane polymers or silane coupling agents to polyimide resins and epoxy resins. However, this can increase the dielectric constant, resulting in insufficient insulation performance. Therefore, there is a need for materials with excellent heat resistance and low dielectric properties.

[0005] 1. The organopolysiloxane prepolymer of the embodiments of the present invention is a condensate of (A) a polydimethylsiloxane having silanol groups at both ends; (B) at least one selected from the group consisting of silane oligomers having alkoxy groups, complete or partial hydrolysates of said silane oligomers, and condensates of said oligomers; (C) at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane; and (D) a silane compound having a phenyl group. 2. The organopolysiloxane prepolymer described in 1 above may have a molar ratio of at least one selected from the group consisting of an alkoxy group-containing silane oligomer, a complete or partial hydrolysate of the silane oligomer, and a condensate of the oligomer (B) to at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane (C), where 0.05 to 6 moles of at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane (C) is given per mole of at least one selected from the group consisting of an alkoxy group-containing silane oligomer, a complete or partial hydrolysate of the silane oligomer, and a condensate of the oligomer (B). 3. In the organopolysiloxane prepolymer described in 1 or 2 above, the phenyl group-containing silane compound (D) may have the following structure. (In the formula, R １ R represents a substituted or unsubstituted phenyl group. ２(where m represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and m is 1 or 2). 4. In another embodiment of the present invention, a silicone composition is provided. This silicone composition comprises an organopolysiloxane prepolymer according to any one of 1 to 3 above, and a curing agent. 5. In the silicone composition according to 4 above, the curing agent may comprise a condensate of a polydimethylsiloxane having trialkoxysilyl groups at both ends and a silane oligomer having a phenyl group and an alkoxy group. 6. In yet another aspect of the present invention, an adhesive is provided. This adhesive comprises a silicone composition according to 4 or 5 above. 7. In yet another aspect of the present invention, a cured body is provided. This cured body is a condensate of an organopolysiloxane prepolymer according to any one of 1 to 3 above and a curing agent.

[0006] According to the organopolysiloxane prepolymer of the embodiment of the present invention, a cured article with excellent heat resistance and adhesive properties can be obtained.

[0007] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0008] A. Organopolysiloxane prepolymer The organopolysiloxane prepolymer of the embodiment of the present invention is a condensate of (A) polydimethylsiloxane having silanol groups at both ends (hereinafter also referred to as polydimethylsiloxane (A)), (B) at least one selected from the group consisting of silane oligomers having alkoxy groups, complete or partial hydrolysates of said silane oligomers, and condensates of said oligomers (hereinafter also referred to as silane oligomer (B)), (C) at least one selected from the group consisting of tetramethoxysilane (hereinafter also referred to as TMOS) and tetraethoxysilane (hereinafter also referred to as TEOS) (hereinafter also referred to as TMOS / TEOS (C)), and (D) a silane compound having a phenyl group (hereinafter also referred to as silane compound having a phenyl group (D)) (hereinafter also referred to as the prepolymer of the embodiment of the present invention). In other words, the organosiloxane prepolymer of the embodiment of the present invention can be obtained by condensing polydimethylsiloxane (A), silane oligomer (B), TMOS / TEOS (C), and a silane compound having a phenyl group (D). The cured body obtained by curing the organopolysiloxane prepolymer obtained by condensing these can have excellent heat resistance and low dielectric properties. Therefore, it can be suitably used in applications where heat resistance and insulation are required. Furthermore, by using the prepolymer of the embodiment of the present invention, a composition with a longer pot life can be obtained. A composition using the prepolymer of the embodiment of the present invention can form a better coating film, and a cured body with a superior appearance can be obtained. In addition, a composition using the prepolymer of the embodiment of the present invention can also have excellent adhesion. By using the prepolymer of the embodiment of the present invention, a composition and cured body with excellent adhesion, heat resistance, and low dielectric properties, which have been difficult to achieve simultaneously until now, can be provided.

[0009] Polydimethylsiloxane (A), silane oligomer (B), and TMOS / TEOS (C) can be used in any appropriate ratio depending on the application of the prepolymer. For example, when obtaining a prepolymer for a cured product used as an insulating layer for a circuit board, a ratio of 1.20 to 1.50 moles of silane oligomer (B) and 0.83 to 4.00 moles of TMOS / TEOS (C) can be used per mole of polydimethylsiloxane (A). Also, for example, when obtaining a prepolymer for use as an adhesive, a ratio of 2 to 4 moles of silane oligomer (B) and 1 to 8.5 moles of TMOS / TEOS (C) can be used per mole of polydimethylsiloxane (A). When obtaining a prepolymer for use as an adhesive layer, it is preferable to adjust the ratio so that the proportion of compounds having alkoxy groups is greater than that of the prepolymer used to form the insulating layer (for example, by increasing the ratio of silane oligomer (B) and / or TMOS / TEOS (C)). A higher proportion of compounds containing alkoxy groups can improve adhesion.

[0010] A-1. Polydimethylsiloxane (A) having silanol groups at both ends. Any suitable polydimethylsiloxane (PDMS) having silanol groups at both ends can be used as the polydimethylsiloxane (A) having silanol groups at both ends. For example, the molecular chain may be linear or branched. It may also have two or more silanol groups at the ends, and may further have any suitable reactive functional group. Preferably, a polydimethylsiloxane having silanol groups at both ends with a linear molecular chain is used. As described above, the silane compound (D) has a phenyl group. Organopolysiloxane prepolymers into which phenyl groups have been introduced may have improved heat resistance. On the other hand, silane compounds having phenyl groups may be difficult to synthesize due to significant steric hindrance. By using polydimethylsiloxane (A) having silanol groups at both ends, phenol groups can be introduced into the organopolysiloxane prepolymer via the polydimethylsiloxane having silanol groups at both ends, and an organopolysiloxane prepolymer with excellent heat resistance can be obtained. Specifically, polydimethylsiloxane (A) represented by the following formula (1) can be suitably used. H-(O-Si(CH) ３ ) ２ ) ｎ -OH (1) (wherein n represents an integer between 70 and 900).

[0011] n is preferably an integer between 70 and 900, and more preferably an integer between 100 and 850. n can be an integer between 134 and 810, such that the number-average molecular weight (Mn) is within the above range.

[0012] The number-average molecular weight (Mn) of polydimethylsiloxane (A), which has silanol groups at both ends, is preferably 10,000 to 60,000, more preferably 10,000 to 45,000, and even more preferably 15,000 to 30,000. If the number-average molecular weight (Mn) of polydimethylsiloxane (A) is within the above range, the compatibility with other raw materials may be improved.

[0013] The weight-average molecular weight (Mw) of polydimethylsiloxane (A), which has silanol groups at both ends, is preferably 15,000 to 132,600, more preferably 15,000 to 97,500, and even more preferably 15,000 to 66,300. If the weight-average molecular weight (Mw) of polydimethylsiloxane (A) is within the above range, the solution used for the condensation of the prepolymer can be easily stirred, and the reaction can be carried out while stirring.

[0014] The molecular weight distribution index (Mw / Mn) of polydimethylsiloxane (A) is preferably 1.3 or higher, more preferably 1.5 or higher, and even more preferably 1.75 or higher. If the (Mw / Mn) of polydimethylsiloxane (A) is within the above range, the mechanical strength of the resulting cured product may be improved. Furthermore, the (Mw / Mn) is preferably 3.0 or lower, more preferably 2.5 or lower, and even more preferably 2.3 or lower. If the molecular weight distribution index (Mw / Mn) is within the above range, the transparency of the resulting cured product may be improved. Furthermore, if the molecular weight distribution index (Mw / Mn) is within the above range, the strength of the resulting cured prepolymer may be improved, and the adhesive strength may be improved when used as an adhesive.

[0015] In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polydimethylsiloxane (A) having silanol groups at both ends refer to the molecular weights in terms of polystyrene obtained by the gel permeation chromatography (GPC) method using polystyrene as a standard sample. Specifically, they can be measured by the following method. <Measurement of average molecular weight> The weight-average molecular weight Mw and number-average molecular weight Mn are measured respectively by the gel permeation chromatography (GPC) method, and the ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn is taken as the molecular weight distribution index. Polystyrene is used as the standard sample, and the measurement is carried out in terms of the converted molecular weight. The measurement of the molecular weight in terms of polystyrene by the GPC method is carried out under the following measurement conditions. Measuring instrument: manufactured by Tosoh Corporation, product name: GPC HLC-8230PC Columns for Mn of 30,000 or less: TSKgel guardColumn Super HZ-H, TSKgel Super HZM-M × 2 Columns for Mn of 30,000 or more (including the case of 50,000 or more): TSKgel guardColumn Super MP(HZ)-N, TSKgel Multipore HZ-N × 3 Oven temperature: 40 °C Eluent: tetrahydrofuran (THF) (1 mL / min) Standard sample: polystyrene Sample preparation: Use a THF solvent added with 0.2% by weight of 2,6-di-tert-butyl-t-phenol (BHT), and let it stand and dissolve at room temperature. Correction: Correct the shift of the GPC peaks between the calibration curve measurement and the sample measurement to perform the molecular weight measurement.

[0016] A-2. Silane oligomers having an alkoxy group, complete or partial hydrolyzates of silane oligomers, and condensates of oligomers (B) As the silane oligomer (B) having an alkoxy group, an oligomer of a silane having any appropriate alkoxy group can be used. The silane oligomer (B) having an alkoxy group is typically represented by the formula (2). The silane oligomer (B) having an alkoxy group may be used alone or in combination of two or more. R ３ O-(Si(OR ４ )) ２ -O) ｏ -R ５ (2) (In the formula (2), R３ , R ４ , and, R ５ Each of these independently represents an alkyl group having 1 to 3 carbon atoms. (where 'o' represents an integer of 2 or more).

[0017] R ３ ~R ５ Each independently represents an alkyl group having 1 to 3 carbon atoms, preferably a methyl group or an ethyl group. Also, o represents an integer of 2 or more, preferably an integer of 3 or more. In practice, o can be an integer of 10 or less. In one embodiment, o is preferably an integer of 4 to 10. Also, in one embodiment, the silane oligomer (B) having an alkoxy group is R ３ ~R ５ The oligomer may be a tetramer to a decamer in which each group is independently either a methyl group or an ethyl group, i.e., the alkoxy group is either a methoxy group or an ethoxy group. If the silane oligomer (B) having an alkoxy group is linear, the decrease in reactivity due to steric hindrance can be suppressed. In addition, complete or partial hydrolysates of silane oligomers having alkoxy groups and condensates of silane oligomers having alkoxy groups can be used, similar to silane oligomer (B) having an alkoxy group. If these are included, the pot life of the composition before curing may be extended, and storage stability may be further improved. One complete or partial hydrolysate of silane oligomers having alkoxy groups and condensates of silane oligomers having alkoxy groups may be used, or two or more may be used in combination.

[0018] A-3. Tetramethoxysilane and tetraethoxysilane (C) TMOS / TEOS (C) may use tetramethoxysilane alone, tetraethoxysilane alone, or a combination of tetramethoxysilane and tetraethoxysilane. It may also be used in combinations having the same alkoxy group as the above-mentioned silane oligomer (B) having an alkoxy group, that is, a combination of a silane oligomer having a methoxy group and tetramethoxysilane, or a combination of a silane oligomer having an ethoxy group and tetraethoxysilane, or in combinations having different alkoxy groups.

[0019] Preferably, among TMOS or TEOS, it is preferable to use a silane oligomer (B) having an alkoxy group and one having a different alkoxy group. If a combination has different alkoxy groups, a prepolymer with alkoxy groups having different reaction temperatures when reacting with hydroxyl groups can be obtained. In such a prepolymer, the alkoxy group with the lower reaction temperature reacts first with the curing agent (e.g., oligomer), and the prepolymer can be crosslinked. Then, the alkoxy group with the higher reaction temperature reacts, and a cured product can be obtained. Therefore, crosslinking of the prepolymer can be performed at a lower temperature. Furthermore, for example, when a composition containing the prepolymer is used as an adhesive, the alkoxy group with the higher reaction temperature selectively reacts at the interface with the adherend, and the adhesiveness can be further improved. More specifically, the methoxy group can react with the terminal silanol groups of polydimethylsiloxane (A) when synthesizing the prepolymer. Also, the ethoxy group can react with the adherend when the composition containing the prepolymer is used as a cured product in the curing reaction, or when it is used as an adhesive and applied for bonding. If the combination contains different alkoxy groups, i.e., a methoxy group or an ethoxy group, then when synthesizing the prepolymer, synthesizing it at a temperature where the methoxy group reacts more readily than the ethoxy group allows the methoxy group to react selectively with the terminal silanol of polydimethylsiloxane (A), and the ethoxy group can remain in the prepolymer. This ethoxy group (i.e., a free ethoxy group) can react with the hydroxyl groups on the surface of the adherend and the silanol groups that have been hydrolyzed from the methoxy group during the curing process for bonding with an adhesive, thereby further accelerating the curing reaction.

[0020] TMOS / TEOS (C) has a molar ratio with the silane oligomer (B) having an alkoxy group of preferably 0.05 mol to 6 mol, more preferably 0.1 mol to 5 mol, and still more preferably 0.2 mol to 4 mol per 1 mol of the silane oligomer (B) having an alkoxy group. That is, in the resulting organopolysiloxane prepolymer, the content ratio of the side chain or terminal substituent derived from the silane oligomer (B) having an alkoxy group and the side chain or terminal substituent derived from TMOS / TEOS can be the above molar ratio. If the content ratio of the silane oligomer (B) having an alkoxy group and TMOS / TEOS (C) is within the above range, the heat resistance and adhesiveness can be further improved. In addition, a prepolymer capable of preparing a composition with a long pot life and excellent handleability can be obtained. Furthermore, the adhesiveness and low dielectric properties of the composition using the obtained prepolymer can be improved.

[0021] A-4. Silane compound (D) having a phenyl group As the silane compound (D) having a phenyl group, any suitable silane compound having a phenyl group is used. By using the silane compound (D) having a phenyl group, the heat resistance of the resulting prepolymer can be improved. Only one kind of the silane compound (D) having a phenyl group may be used, or two or more kinds may be used in combination. For example, two kinds of diphenylsilane compounds may be used in combination.

[0022] The silane compound (D) having a phenyl group is preferably a silane compound represented by the following formula. (In the formula, R １ represents a substituted or unsubstituted phenyl group, R ２ represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and m is 1 or 2).

[0023] R ２ represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, preferably a substituted or unsubstituted alkyl group having 1 or 2 carbon atoms. R ２ may be the same or different.

[0024] Specific examples of the silane compound (D) having a phenyl group include phenyltriethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, phenyltripropoxysilane, phenyltriisopropoxysilane, and the like. Further, oligomers of substituted or unsubstituted phenylalkoxysilanes such as methoxy group-containing phenyl / methyl-based alkoxyoligomers, or compounds in which a phenyl group and a trialkoxysilane are bonded via any bonding group (for example, an aminopropyl group) such as N-phenyl-3-aminopropyltrimethoxysilane may be used as the silane compound (D) having a phenyl group.

[0025] As the silane compound (D) having a phenyl group, commercially available products may be used. For example, product names manufactured by Shin-Etsu Chemical Co., Ltd., such as "KBM-103", "KBM-202SS", "KBE-103", "KR-213", "KR-401", "KR-510", "KBM-573", and the like can be mentioned.

[0026] The silane compound (D) having a phenyl group can be used in any appropriate content according to the amount of the phenyl group introduced into the prepolymer. The content of the silane compound (D) having a phenyl group is preferably 1 mol to 7 mol, more preferably 2 mol to 6 mol, per 1 mol of the polydimethylsiloxane (A).

[0027] A-5. Organometallic Compounds Any other suitable components may be further used in the condensation of the prepolymers in the embodiments of the present invention. Preferably, organometallic compounds are used as condensation catalysts. Examples of organometallic compounds include tin (Sn)-based catalysts such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin bisacetylacetonate, dibutyltin dimaleate, dibutyltin di(2-ethylhexanoate), and tin octoate; titanium (Ti)-based catalysts such as tetraisopropyl titanate, tetrabutyl titanate, and tetra-2-ethylhexyl titanate; aluminum (Al)-based catalysts such as triisopropyl aluminate; zinc (Zn)-based catalysts such as dimethoxyzinc, diethoxyzinc, and zinc octoate; zirconium (Zr)-based catalysts such as tetraisopropyl zirconate, tetrabutyl zirconate, and oxozirconium octoate; and bismuth (Bi)-based catalysts such as bismastris (2-ethylhexanoate) or bismastris (neodecanoate). Sn-based catalysts are preferred because they are highly reactive, allowing for effective condensation reactions with small amounts, and they are less likely to cause reduced heat resistance or discoloration of the cured material if residue remains. Organometallic compounds may be used individually or in combination of two or more.

[0028] The content of organometallic compounds is preferably 0.05% by weight or less, more preferably 0.01% by weight or less, even more preferably 0.005% by weight or less, and particularly preferably 0.0005% by weight or less, relative to the solid content. The content of organometallic compounds is preferably 0.00001% by weight or more, relative to the solid content.

[0029] A-6. Method for Preparing Prepolymers The prepolymers of the embodiments of the present invention can be obtained by condensing a polydimethylsiloxane (A) having silanol groups at both ends, a silane oligomer (B) having an alkoxy group, TMOS / TEOS (C), and a silane compound (D) having a phenyl group by any suitable method. Preferably, in the presence of an organometallic compound acting as a condensation catalyst, the polydimethylsiloxane (A) having silanol groups at both ends, the silane oligomer (B) having an alkoxy group, and TMOS / TEOS (C) are condensed by a condensation reaction by dehydration or dealcoholization. Then, the silane compound (D) having a phenyl group is added to the reaction solution obtained from the condensation reaction and the condensation reaction is carried out further to obtain the prepolymers of the embodiments of the present invention. In addition, instead of organometallic compounds, phosphate ester compounds such as trimethyl phosphate and triethyl phosphate may be used as condensation catalysts in the above reaction. Furthermore, an acid catalyst such as hydrochloric acid, an alkaline catalyst such as ammonia, etc. may be used for hydrolysis.

[0030] The reaction temperature can be set to any appropriate value. Preferably, it is 40°C to 140°C, and more preferably, 60°C to 120°C. The reaction time can also be set to any appropriate value. Preferably, it is 0.5 hours to 24 hours, and more preferably, 6 hours to 20 hours.

[0031] B. Silicone Composition The silicone composition of the embodiment of the present invention comprises the prepolymer and curing agent of the embodiment of the present invention described above. As described above, the prepolymer of the embodiment of the present invention can provide a cured body with excellent heat resistance and low dielectric properties. Therefore, it can be suitably used as a encapsulant for semiconductor devices and for forming interlayer insulating films. Furthermore, the silicone composition using the prepolymer of the embodiment of the present invention can also exhibit excellent adhesion. Therefore, it can be used as an adhesive composition and can be suitably used as an insulating adhesive.

[0032] B-1. Curing Agent Any suitable curing agent can be used as the curing agent included in the silicone resin composition of the embodiment of the present invention. For example, organometallic compounds as exemplified in item A-5 above can be used. Preferably, organometallic salts such as zinc octoate, oxozirconium octoate, tin octoate, and dibutyltin dimaleate are used as organometallic compounds. Using these can lower the curing temperature of the composition and improve the efficiency of manufacturing the cured body. In addition, a cured body with greater thickness can be obtained. Commercially available organometallic salts may be used. Examples of commercially available products include Nikka Octix® Zinc and Nikka Octix® Zirconium, manufactured by Nippon Chemical Industries, Ltd. Only one organometallic compound may be used, or two or more may be used in combination.

[0033] The organometallic salt can be used in any appropriate amount. Preferably, it is 0.01 to 5 parts by weight, more preferably 0.05 to 5 parts by weight, and even more preferably 0.1 to 3 parts by weight, per 100 parts by weight of the prepolymer. If the content of the organometallic salt is within the above range, the curing reaction of the prepolymer can be adequately promoted.

[0034] It is preferable to use a combination of an organometallic compound and a tetraalkoxysilane oligomer as the curing agent. By using an organometallic compound and a tetraalkoxysilane oligomer in combination, the crosslinking density can be improved, and a cured product with higher hardness can be obtained. In addition, the tack strength of the surface of the resulting cured product can be reduced. Furthermore, a large number of alkoxy groups can be coordinated, which can improve the adhesion of the composition and the water resistance of the resulting cured product. Specific examples of tetraalkoxysilane oligomers include tetraethoxysilane oligomers. A single tetraalkoxysilane oligomer may be used, or two or more may be used in combination.

[0035] The tetraalkoxysilane oligomer can be used in any appropriate amount. Preferably, it is 1 to 30 parts by weight, more preferably 3 to 20 parts by weight, and even more preferably 5 to 15 parts by weight, per 100 parts by weight of the prepolymer. If the content of the tetraalkoxysilane oligomer is within the above range, the prepolymer can be properly cured.

[0036] B-2. Prepolymer-type curing agent In one embodiment, a prepolymer-type curing agent may be used as the curing agent. By using a prepolymer-type curing agent in combination with the organopolysiloxane prepolymer of the above embodiment of the present invention, the heat resistance of the silicone composition (the resulting cured product) can be further improved. Any suitable prepolymer can be used as the prepolymer-type curing agent. For example, a prepolymer obtained by hydrolysis and condensation reaction of a polydimethylsiloxane having silanol groups at both ends and a silane compound having a phenyl group can be used as the prepolymer-type curing agent.

[0037] Any suitable polydimethylsiloxane having silanol groups at both ends can be used as the polydimethylsiloxane. Specifically, the polydimethylsiloxane exemplified in section A above can be used. Only one type of polydimethylsiloxane having silanol groups at both ends may be used in the prepolymer-type curing agent, or two or more types may be used in combination. Furthermore, the polydimethylsiloxane having silanol groups at both ends used in the prepolymer-type curing agent may be the same polydimethylsiloxane (A) having silanol groups at both ends used in the preparation of the prepolymer, or it may be a different polydimethylsiloxane.

[0038] Any suitable silane compound having a phenyl group can be used. Specifically, the silane compounds having a phenyl group exemplified in section A above can be used. Specifically, silane compounds having one or two phenyl groups and two or three alkoxy groups are used. The alkoxy groups are any suitable alkoxy groups, preferably ethoxy or methoxy groups. Only one silane compound having a phenyl group may be used, or two or more may be used in combination. Furthermore, the silane compound having a phenyl group used in the prepolymer-type curing agent may be the same silane compound having a phenyl group (D) used in the preparation of the prepolymer, or it may be a different silane compound.

[0039] The silane compound having a phenyl group can be used in any appropriate amount. For example, it is preferably 1 to 6 moles, more preferably 1.5 to 5 moles, and even more preferably 2 to 4 moles, per mole of polydimethylsiloxane having silanols at both ends. If the content of the silane compound having a phenyl group is within the above range, a silicone composition can be obtained that provides a cured product with heat resistance at higher temperatures (e.g., 250°C) and adhesive properties.

[0040] The prepolymer-type curing agent can be used in any appropriate amount. Preferably, it is 15 to 300 parts by weight, more preferably 25 to 250 parts by weight, and even more preferably 35 to 150 parts by weight, per 100 parts by weight of the prepolymer.

[0041] The prepolymer-type curing agent can be obtained by any suitable method. For example, it can be obtained by hydrolysis and condensation reaction of a polydimethylsiloxane having silanol groups at both ends and a silane compound having a phenyl group, using an organometallic catalyst or a metal alkoxide catalyst. Any suitable organometallic compound can be used as the organometallic catalyst. Examples include organotin compounds such as dibutyltin dilaurate and dibutyltin di-2-ethylhexoate, or organometallic compounds of bismuth, zinc, or zirconium. Any suitable metal alkoxide can be used as the metal alkoxide catalyst. Examples include organotitanium compounds such as tetra(2-ethylhexyl) titanate. Preferably, a metal alkoxide is used.

[0042] The metal alkoxide is used in any appropriate amount. The content of the metal alkoxide is preferably 0.05 to 0.2 moles, more preferably 0.075 to 0.175 moles, and even more preferably 0.09 to 0.12 moles, per mole of polydimethylsiloxane having silanols at both ends.

[0043] The prepolymer-type curing agent preferably has a molecular weight distribution index (Mw / Mn), calculated as the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), of 2.0 to 6.0, more preferably 2.5 to 5.5, and even more preferably 2.8 to 5.0. If the molecular weight distribution index (Mw / Mn) is within the above range, the heat resistance of the resulting silicone composition can be further improved. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the prepolymer-type curing agent can be measured by the method described above.

[0044] The polydimethylsiloxane having silanol groups at both ends used in the preparation of the propromolecular curing agent preferably has a molecular weight distribution index (Mw / Mn), calculated as the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), of 1.3 to 3.0, more preferably 1.5 to 2.5, and even more preferably 1.75 to 2.3. If the molecular weight distribution index (Mw / Mn) of the polydimethylsiloxane having silanol groups at both ends is within the above range, the heat resistance of the silicone composition can be further improved. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polydimethylsiloxane having silanol groups at both ends can be measured by the method described above.

[0045] B-3. ​​Other Additives The silicone composition of the embodiment of the present invention may further contain any other suitable additives other than the prepolymer and the curing agent. Any suitable material can be used as the additive depending on the application of the silicone composition. Examples include organic solvents, mold release agents, colorants, viscosity modifiers, polymerization inhibitors, curing accelerators, defoamers, dispersants, heat stabilizers, surfactants, lubricants, antistatic agents, UV absorbers, bluing agents, fillers, thermoplastic resins, etc. Only one additive may be used, or two or more may be used in combination. Additives can be used in any suitable amount.

[0046] Silicone compositions can be prepared by any suitable method. For example, they can be prepared by adding and mixing a curing agent and any additives to a solution obtained by the condensation reaction of organopolysiloxane prepolymers.

[0047] C. Cured Body The cured body of the embodiment of the present invention is obtained by curing the above-mentioned prepolymer. Any suitable curing agent can be used as the curing agent. Specifically, the above-mentioned curing agent can be used. As described above, the cured body of the embodiment of the present invention has excellent heat resistance, low dielectric properties, and can also have excellent adhesive properties. Therefore, it can be suitably used in applications where heat resistance and insulation properties are required, such as semiconductor encapsulants and adhesive compositions such as insulating adhesives.

[0048] In one embodiment, the cured body can be obtained by heating at a heating temperature of 120°C or higher for 30 minutes or more. Heating at a heating temperature of 120°C or higher for 30 minutes or more allows the composition containing the prepolymer to cure without forming a film on the surface. If curing is performed at a temperature below 120°C, the deethanolization reaction may not proceed smoothly, a film may form at the interface between the air and the cured body, and the interior may remain uncured. As described above, the cured bodies of the embodiments of the present invention have excellent heat resistance, and thermal decomposition can be suppressed even when heated at high temperatures for a long time.

[0049] D. Applications The prepolymer of the embodiment of the present invention can provide a cured body with excellent heat resistance and low dielectric properties. Furthermore, a cured body with excellent adhesive properties can be obtained by using the prepolymer of the present invention. Therefore, it can be suitably used in applications where such properties are required. Specifically, it can be suitably used in adhesive compositions such as semiconductor encapsulants, insulating adhesives, or adhesives where transparency is required. When using the prepolymer of the embodiment of the present invention as an adhesive, the prepolymer of the embodiment of the present invention can be used in combination with any other suitable additive. In one embodiment, the adhesive of the embodiment of the present invention comprises the organosiloxane prepolymer and a curing agent. Any suitable curing agent can be used as the curing agent. Specifically, the curing agent described above can be used.

[0050] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0051] [Manufacturing Example 1] Preparation of curing agent 1 58 parts by weight of TEOS oligomer (pentamer to decamer) (manufactured by Evonik, product name "SilBond 50"), 25 parts by weight of Nikka Octic® Zirconium (manufactured by Nippon Chemical Industries Co., Ltd.), and 16 parts by weight of Nikka Octic® Zinc (manufactured by Nippon Chemical Industries Co., Ltd.) were mixed to obtain curing agent 1 (oligomer-type curing agent).

[0052] [Production Example 2] Preparation of curing agent 2: 96.95 parts by weight of polydimethylsiloxane having silanol groups at both ends (manufactured by Nusil Technology, product name "PLY2-7630", number average molecular weight Mn: 27,100, weight average molecular weight Mw: 59,902, molecular weight distribution index Mw / Mn: 2.21) and 2.81 parts by weight of a silane compound having a phenyl group and an alkoxy group (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBE-103", a silane compound having one phenyl group and three ethoxy groups (triethoxyphenylsilane)) were added and stirred until homogeneous. Next, 0.24 parts by weight of a condensation initiator (manufactured by Matsumoto Fine Chemical Co., Ltd., trade name "TA-30", titanium ethylhexide) was added and the mixture was reacted at 40°C for 6 hours. After that, it was allowed to cool naturally to obtain curing agent 2 (prepolymer type curing agent). The number average molecular weight Mn and weight average molecular weight Mw were measured by the following methods. The weight average molecular weight Mw and number average molecular weight Mn were measured by gel permeation chromatography (GPC), and the ratio of weight average molecular weight Mw to number average molecular weight Mn was used as the molecular weight distribution index. Polystyrene was used as the standard sample and measured as the converted molecular weight. The measurement of polystyrene converted molecular weight by GPC was performed under the following measurement conditions. Measuring instrument: Tosoh Corporation, product name: GPC HLC-8230PC Columns with Mn 30,000 or less: TSKgel guardColumn Super HZ-H, TSKgel Super HZM-M × 2 Columns with Mn 30,000 or more (including cases with Mn 50,000 or more): TSKgel guardColumn Super MP(HZ)-N, TSKgel Multipore HZ-N × 3 Oven temperature: 40℃ Eluent: Tetrahydrofuran (THF) (1 mL / min) Standard sample: Polystyrene Sample preparation: Dissolved in THF solvent with 0.2% by weight of 2,6-di-Tert-butyltphenol (BHT) added, by standing at room temperature. Correction: The difference in GPC peaks between calibration curve measurement and sample measurement was corrected before performing molecular weight measurement.

[0053] [Examples 1-1 and 1-2] A four-necked reaction vessel equipped with a stirrer and a thermometer was filled to capacity with nitrogen gas. 91.7% by weight of polydimethylsiloxane (A) having silanol groups at both ends (Nusil Technology, product name "PLY2-7630", number average molecular weight Mn: 27,100, weight average molecular weight Mw: 59,902, molecular weight distribution index Mw / Mn: 2.21) and 5.04% by weight of a mixture of alkoxy-containing silane oligomer (B) and tetramethoxysilane and tetraethoxysilane (C) (Evonik, product name "SilBond40", mixture of tetramers to decamers of tetraethoxysilane and tetraethoxysilane, tetraethoxysilane content: 25% by weight) were placed in a reaction vessel filled with nitrogen gas and stirred until homogenized. Next, 0.0004% by weight of a condensation catalyst (dibutyltin dilaurate, manufactured by Tokyo Chemical Industry Co., Ltd.) was added and the mixture was reacted at 85°C for 6 hours. After that, it was allowed to cool naturally to obtain solution A. Next, 3.25% by weight of a silane compound (D) having a phenyl group (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBE-103", a silane compound having one phenyl group and three ethoxy groups (triethoxyphenylsilane)) was added to solution A and the mixture was reacted at 100°C for 3 hours. After that, it was allowed to cool naturally to obtain an organopolysiloxane prepolymer. After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 2.74 Ps·s (25°C). Subsequently, the obtained prepolymer and the curing agent 1 were mixed to obtain a silicone composition (curing agent content in the silicone composition: 2.9% by weight, Example 1-1). Similarly, the obtained prepolymer was mixed with the curing agent 2 to obtain a silicone composition (curing agent content in the silicone composition was 50% by weight, Examples 1-2).

[0054] [Examples 2-1 and 2-2] An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 92.82% by weight of component (A) was used, 1.85% by weight of KC-89S (manufactured by Shin-Etsu Silicone Co., Ltd., a low-molecular-weight methyl oligomer of tetramethoxysilane) was used as component (B), 0.43% by weight of TEOS (manufactured by Tama Chemical Co., Ltd., trade name "Ethyl Orthosilicate") was used as component (C), and 3.29% by weight of component (D). After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 2.31 Ps·s (25°C). Subsequently, the obtained prepolymer and the curing agent 1 were mixed to obtain a silicone composition (curing agent content in the silicone composition: 2.9% by weight, Example 2-1). Similarly, the obtained prepolymer and the curing agent 2 were mixed to obtain a silicone composition (curing agent content in the silicone composition: 50% by weight, Example 2-2).

[0055] [Examples 3-1 and 3-2] (A) Component was used at 91.66% by weight, (B) Component was ethyl silkate 40 (manufactured by Colcoat, Si ５ O ４ (OEt) １２ An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 3.03% by weight of (average pentamer) was used, 2.06% by weight of TEOS (manufactured by Tama Chemical Co., Ltd., trade name "Ethyl Orthosilicate") was used as component (C), and 3.25% by weight of component (D) was used. After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 3.04 Ps·s (25°C). Subsequently, the obtained prepolymer and the curing agent 1 were mixed to obtain a silicone composition (curing agent content in the silicone composition: 2.9% by weight, Example 3-1). Similarly, the obtained prepolymer and the curing agent 2 were mixed to obtain a silicone composition (curing agent content in the silicone composition: 70% by weight, Example 3-2).

[0056] [Example 4] An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 89.29% by weight of component (A) was used, 7.28% by weight of KC-89S (manufactured by Shin-Etsu Silicone Co., Ltd., a low-molecular-weight methyl oligomer of tetramethoxysilane) was used as component (B), 2.44% by weight of TMOS (manufactured by Tokyo Chemical Industry Co., Ltd., trade name "T0588") was used as component (C), and 1.98% by weight of component (D). After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 2.8 Ps·s (25°C). Thereafter, the obtained prepolymer and the curing agent 1 were mixed to obtain a silicone composition (curing agent content in the silicone composition was 2.9% by weight).

[0057] (Comparative Example 1) An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 94.79% by weight of component (A) was used, 5.21% by weight of a mixture of an alkoxy-group-containing silane oligomer (B) and tetramethoxysilane and tetraethoxysilane (C) (manufactured by Evonik, product name "SilBond 40", a mixture of tetramers to decamers of tetraethoxysilane and tetraethoxysilane, tetraethoxysilane content: 25% by weight) was used, and component (D) was not added. After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 2.58 Ps·s (25°C). Thereafter, the obtained prepolymer and the curing agent 1 were mixed to obtain a silicone composition (curing agent content in the silicone composition: 2.9% by weight, Comparative Example 1).

[0058] (Comparative Example 2) An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 91.7% by weight of component (A) was used, 5.05% by weight of KC-89S (manufactured by Shin-Etsu Silicone Co., Ltd., a low-molecular-weight methyl oligomer of tetramethoxysilane) was used as component (B) (component (C) was not included), and 3.25% by weight of component (D) was used. After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 2.82 Ps·s (25°C).

[0059] (Comparative Example 3) (A) Component was used at 91.7% by weight, (B) Component was ethyl silkate 40 (manufactured by Colcoat, Si ５ O ４ (OEt) １２ An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 5.05% by weight of (average pentamer) was used (excluding component (C)) and 3.25% by weight of component (D) was used. After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 6.68 Ps·s (25°C).

[0060] (Comparative Example 4) (A) Component was used at 90.08% by weight, (B) Component was ethyl silkate 40 (manufactured by Colcoat, Si ５ O ４ (OEt) １２ An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 9.92% by weight of (average pentamer) was used (excluding component (C)) and component (D) was not added. After cooling to 25°C, the viscosity of the prepolymer was measured. The viscosity of the prepolymer was 12.31 Ps·s (25°C).

[0061] [Evaluation] The following evaluations were performed using the organopolysiloxane prepolymers obtained in the examples and comparative examples. The results are shown in Table 1.

[0062] 1. The organopolysiloxane prepolymers obtained in the pot-life examples or comparative examples were measured at 25°C using an E-type viscometer (TOKI SANGYO, product name "VISCOMETER TV-35") to determine their viscosity immediately after synthesis and after storage at 25°C for one week. The viscosity increase rate was calculated from the respective viscosity values ​​using the following formula: Viscosity increase rate (%) = {(Viscosity after one week (Pa·s)) - (Viscosity immediately after synthesis (Pa·s))} / (Viscosity at the start of measurement (Pa·s)) × 100 ◎: Viscosity increase of 5% or less in one week 〇: Viscosity increase of more than 5% and 20% or less in one week △: Viscosity increase of more than 20% in one week (evaluation of cured material was not performed) ×: Gelated after one week of storage (evaluation of cured material was not performed)

[0063] 2. To 100 parts by weight of the solid content of the organopolysiloxane prepolymer obtained in the Adhesion Examples or Comparative Examples, 3 parts by weight of the curing agent prepared in Production Example 1 was added and the mixture was stirred and degassed. Next, a film was formed on a Teflon® vat to obtain a silicone composition. The obtained silicone composition was applied to the entire surface of one side of an aluminum plate (manufactured by AS ONE, aluminum plate material, thickness 0.3 mm, size 2 cm × 4 cm) to a coating thickness of 80 μm. Next, the plate was preheated at 60°C for 30 minutes, and then heated at 200°C for 3 hours to cure the silicone composition, and this was used as a sample. Similarly, the silicone composition was applied to copper foil (manufactured by AS ONE, copper plate material, thickness 50 μm, size 2 cm × 4 cm) to obtain a sample. The breaking strength of these samples was measured using an Autograph (manufactured by Shimadzu Corporation, product name "AG-X 20kN or AG-X 1kN"), and the value of the breaking strength (N / cm) was measured. ２ The tensile shear adhesive strength was defined as 10 N / cm². An appropriate autograph was used depending on the tensile shear adhesive strength. Measurements were taken for three samples and the average value was calculated. The adhesive strength values ​​obtained were evaluated according to the following criteria: ◎: Adhered to both aluminum plate and copper foil, with a tensile shear adhesive strength of 10 N / cm² in both cases. ２ The above is correct. ○: It adheres to both aluminum plate and copper foil, and the tensile shear adhesive strength is 10 N / cm in both cases. ２ Less than △: When bonded to an aluminum plate or copper foil, the tensile shear bond strength is 10 N / cm. ２ Less than ×: Does not adhere to either aluminum plate or copper foil.

[0064] 3. Heat Resistance To 100 parts by weight of the solids content of the organopolysiloxane prepolymer obtained in Examples 1 to 4 or Comparative Example 1, 5 parts by weight of the curing agent prepared in Production Example 1 was added, and the mixture was stirred and degassed to obtain silicone compositions 1-1, 2-1, 3-1, 4, or C1. Similarly, to 50 parts by weight of the solids content of the organopolysiloxane prepolymer obtained in Examples 1 to 3, 50 parts by weight of the curing agent prepared in Production Example 2 was added, and the mixture was stirred and degassed to obtain silicone compositions 1-2, 2-2, and 3-2. Approximately 1.5 g of the obtained silicone composition was weighed into an aluminum cup, and the aluminum cup was then placed in an oven at 250°C and held for 100 hours. After that, the aluminum cup was removed from the oven and allowed to cool to room temperature. The weight of the aluminum cup was then weighed, and the weight loss rate was calculated from the weight before and after heating using the following formula. Weight loss rate = (W1 - W2) / W1 × 100 (%) W1: Weight (parts by weight) of the silicone composition and aluminum cup before heating at 250°C for 100 hours W2: Weight (parts by weight) of the silicone composition and aluminum cup after heating at 250°C for 100 hours ◎: Weight loss of less than 7% after 100 hours of storage at 250°C 〇: Weight loss of more than 7% and less than or equal to 10% after 100 hours of storage at 250°C △: Weight loss of more than 10% after 100 hours of storage at 250°C ×: Appearance defects such as cracks after 100 hours of storage at 250°C

[0065] 4. To 100 parts by weight of the solid content of the organopolysiloxane prepolymer obtained in Electrical Insulation Examples 1 to 4 or Comparative Example 1, 5 parts by weight of the curing agent prepared in Production Example 1 was added, and the mixture was stirred and degassed to obtain silicone compositions 1-1, 2-1, 3-1, 4, or C1. Similarly, to 50 parts by weight of the solid content of the organopolysiloxane prepolymer obtained in Examples 1, 2, and 3, 50 parts by weight of the curing agent prepared in Production Example 2 was added, and the mixture was stirred and degassed to obtain silicone compositions 1-2, 2-2, and 3-2. The obtained silicone compositions were transferred to a Teflon® petri dish and cured to prepare test specimens. Using these test specimens, dielectric breakdown tests were performed in accordance with JIS C 2110-1 "Solid electrical insulating materials - Test method for dielectric breakdown strength - Part 1: Test by application of commercial frequency AC voltage". A test specimen was placed in an oil bath filled with insulating oil (Idemitsu Transformer Oil G, compliant with JIS C2320 insulating oil). The approximate center of the specimen was sandwiched between an upper electrode with a diameter of 20 mm and a lower electrode with a diameter of 25 mm, and lead wires were connected to the electrodes. Subsequently, the power supply voltage was increased at a constant boosting rate using an AC voltage generator (100 kV-20 kVA, manufactured by Tokyo Transformer Co., Ltd.), and the dielectric breakdown voltage was measured. The dielectric breakdown strength was calculated by dividing the obtained dielectric breakdown voltage (kV) by the thickness of the sample (mm). The obtained dielectric breakdown strength values ​​were evaluated according to the following criteria: ◎: 20 kV / mm or more ○: 15 kV / mm or more and less than 20 kV / mm △: less than 15 kV / mm

[0066] 5. Volume Resistivity To 100 parts by weight of solids of the organopolysiloxane prepolymer obtained in Examples 1-4 or Comparative Example 1, 5 parts by weight of the curing agent prepared in Production Example 1 was added, and the mixture was stirred and degassed to obtain silicone compositions 1-1, 2-1, 3-1, 4, or C1. Similarly, to 50 parts by weight of solids of the organopolysiloxane prepolymer obtained in Examples 1, 2, and 3, 50 parts by weight of the curing agent prepared in Production Example 2 was added, and the mixture was stirred and degassed to obtain silicone compositions 1-2, 2-2, and 3-2. The obtained silicone compositions were transferred to a Teflon® petri dish and cured to prepare test specimens. The volume resistivity was measured according to the method compliant with JIS K 6911 "General Test Methods for Thermosetting Plastics". The test specimen was sandwiched between a disc-shaped lower electrode and a disc-shaped upper electrode (guard electrode outer diameter 80 mm) with a contact area diameter of 50 mm. A DC voltage of 500V to 1000V was applied using the double-ring method with a digital ultra-high resistance / micro-current meter (ADCMT, product name 5450), and the current value was measured. Voltage value (V) / electrode area (cm²) ２ The volume resistivity ρ (Ω·cm) was calculated by multiplying by (voltage value (V) / current value (A)) and dividing by the sample thickness (cm) and current value (A). Volume resistivity ρ (Ω·cm) = (voltage value (V) / current value (A)) × (electrode area (cm) ２ )) / (sample thickness (cm)) The obtained volume resistivity was evaluated according to the following criteria: ◎: 1 × 10 －１５ Ω・cm or more 〇: 1×10 －１２ Ω·cm exceeds 1 × 10⁻⁶ －１５ Less than Ω・cm △: 1 × 10 －６ Ω·cm exceeds 1 × 10⁻⁶ －１２ Ω・cm or less ×: 1×10 －６ Ω・cm or less, conductive

[0067]

[0068] The cured articles using the organopolysiloxane prepolymers in the embodiments of the present invention exhibited excellent heat resistance and low dielectric properties. They also demonstrated excellent adhesive properties.

[0069] The organopolysiloxane prepolymer of the present invention can be suitably used in applications such as semiconductor encapsulants (insulating encapsulants, gels), and insulating adhesives.

Claims

1. An organopolysiloxane prepolymer that is a condensate of: (A) a polydimethylsiloxane having silanol groups at both ends; (B) at least one selected from the group consisting of silane oligomers having alkoxy groups, complete or partial hydrolysates of said silane oligomers, and condensates of said oligomers; (C) at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane; and (D) a silane compound having a phenyl group.

2. The organopolysiloxane prepolymer according to claim 1, wherein the molar ratio of at least one selected from the group consisting of a silane oligomer having an alkoxy group, a complete or partial hydrolysate of the silane oligomer, and a condensate of the oligomer, to at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane (C) is 0.05 moles to 6 moles of at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane (C) per mole of at least one selected from the group consisting of a silane oligomer having an alkoxy group, a complete or partial hydrolysate of the silane oligomer, and a condensate of the oligomer (B).

3. The organopolysiloxane prepolymer according to claim 1, wherein the silane compound (D) having a phenyl group has the following structure. (In the formula, R １ R represents a substituted or unsubstituted phenyl group. ２ (where m represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and m is 1 or 2).

4. A silicone composition comprising an organopolysiloxane prepolymer according to any one of claims 1 to 3 and a curing agent.

5. The silicone composition according to claim 4, wherein the curing agent comprises a condensate of a polydimethylsiloxane having trialkoxysilyl groups at both ends and a silane oligomer having a phenyl group and an alkoxy group.

6. An adhesive comprising the silicone composition described in claim 4.

7. A cured body which is a condensate of an organopolysiloxane prepolymer according to any one of claims 1 to 3 and a curing agent.

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