Organopolysiloxane prepolymer and cured body of said organopolysiloxane prepolymer

Abstract

Provided is an organopolysiloxane prepolymer that can provide a cured body having excellent heat resistance and low dielectric characteristics. An organopolysiloxane prepolymer according to an embodiment of the present invention is obtained through condensation of: (A) a polydimethylsiloxane having silanol groups at both terminals; (B) at least one selected from the group consisting of silane oligomers having an alkoxy group, 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 fluoroalkyl group. Regarding the molar ratio of (B) the silane oligomer having an alkoxy group and (C) said at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane, (C) said at least one selected from the group consisting of tetramethoxysilane and tetraethoxysilane is contained in an amount of 0.25-5.59 mol with respect to 1 mol of (B) the silane oligomer having an alkoxy group.

Description

Organopolysiloxane prepolymer and cured product of said organopolysiloxane prepolymer

[0001] The present invention relates to an organopolysiloxane prepolymer and a cured product of the organopolysiloxane prepolymer.

[0002] Semiconductor encapsulants are used to protect semiconductor elements from light, heat, fine particles such as dust, and external impacts. Semiconductor encapsulants are required to have properties such as heat resistance, moisture resistance, impact resistance, and electrical insulation. Known materials for semiconductor encapsulants include epoxy resins and urethane resins (see, for example, Patent Documents 1 and 2).

[0003] Patent No. 7460025 Patent No. 7289568

[0004] Polyimide resins and liquid crystal polymers are known as resins with low dielectric properties. However, because they lack adhesive properties, they require the use of a bonding material, which may result in insufficient heat resistance. It has also been proposed to add condensation-type polydimethylsiloxane polymers or silane coupling agents to polyimide resins and epoxy resins to improve adhesion. However, this increases the relative dielectric constant, and may result in insufficient insulation performance. Therefore, there is a demand for materials with excellent heat resistance and low dielectric properties.

[0005] 1. The organopolysiloxane prepolymer of the present invention is an organopolysiloxane prepolymer obtained by condensing (A) a polydimethylsiloxane having silanol groups at both ends, (B) at least one member selected from the group consisting of a silane oligomer having an alkoxy group, a complete or partial hydrolyzate of the silane oligomer, and a condensate of the oligomer, (C) at least one member selected from the group consisting of tetramethoxysilane and tetraethoxysilane, and (D) a silane compound having a fluoroalkyl group, wherein the molar ratio of the silane oligomer (B) having an alkoxy group to the at least one member (C) selected from the group consisting of tetramethoxysilane and tetraethoxysilane is 0.25 to 5.59 moles of the at least one member (C) selected from the group consisting of tetramethoxysilane and tetraethoxysilane per mole of the silane oligomer (B) having an alkoxy group. In the organopolysiloxane prepolymer described in 1 above, the at least one member (B) selected from the group consisting of silane oligomers having alkoxy groups, complete or partial hydrolysates of the silane oligomers, and condensates of the oligomers may be a tetramer to a decamer, and the alkoxy group may be a methoxy group or an ethoxy group. 3. In one embodiment of the present invention, a silicone composition is provided. The silicone composition of this embodiment comprises the organopolysiloxane prepolymer described in 1 or 2 above and a curing agent. 4. In the silicone composition of 3 above, the curing agent may comprise a tetraalkoxysilane oligomer and an organic acid metal salt. 5. In another embodiment of the present invention, a sealant is provided. The sealant of this embodiment may comprise the organopolysiloxane prepolymer described in 1 or 2 above. 6. In yet another embodiment of the present invention, an adhesive composition is provided. The adhesive composition of this embodiment may comprise the organopolysiloxane prepolymer described in 1 or 2 above. 7. In yet another embodiment of the present invention, there is provided a cured product. The cured product of this embodiment of the present invention is a cured product of the organopolysiloxane prepolymer described in 1 or 2 above.8. The cured product according to 7 above may have a relative dielectric constant of 3 or less at 10 GHz.

[0006] According to the organopolysiloxane prepolymer of the present invention, a cured product having excellent heat resistance and low dielectric properties can be obtained.

[0007] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0008] A. Organopolysiloxane Prepolymer The organopolysiloxane prepolymer of an embodiment of the present invention is an organopolysiloxane prepolymer (hereinafter also referred to as a prepolymer of an embodiment of the present invention) obtained by condensing (A) a polydimethylsiloxane having silanol groups at both ends (hereinafter also referred to as polydimethylsiloxane (A)), (B) at least one member selected from the group consisting of a silane oligomer having an alkoxy group, a complete or partial hydrolyzate of the silane oligomer, and a condensate of the oligomer (hereinafter also referred to as silane oligomer (B)), (C) at least one member 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 fluoroalkyl group (hereinafter also referred to as silane compound (D) having a fluoroalkyl group). The molar ratio of the alkoxy-containing silane oligomer (B) to the at least one (C) selected from the group consisting of tetramethoxysilane and tetraethoxysilane is 0.25 to 5.59 moles of the at least one (C) selected from the group consisting of tetramethoxysilane and tetraethoxysilane per mole of the alkoxy-containing silane oligomer (B). In other words, the resulting organopolysiloxane prepolymer can have the above molar ratio of the side chain or terminal substituent derived from the alkoxy-containing silane oligomer (B) to the side chain or terminal substituent derived from TMOS / TEOS. A cured product obtained by curing the organopolysiloxane prepolymer obtained by condensing these components can have excellent heat resistance and low dielectric properties. Therefore, it can be suitably used in applications requiring heat resistance and insulating properties. Furthermore, the use of a prepolymer according to an embodiment of the present invention can produce a composition with a longer pot life. A composition using a prepolymer according to an embodiment of the present invention can form a coating film more satisfactorily, and a cured product with excellent appearance can be obtained. Furthermore, a composition using the prepolymer according to an embodiment of the present invention can also have excellent adhesive properties.By using the prepolymer according to the embodiment of the present invention, it is possible to provide a composition and a cured product that are excellent in adhesion, heat resistance, and low dielectric properties, which have been difficult to achieve together until now.

[0009] The polydimethylsiloxane (A), silane oligomer (B), and TMOS / TEOS (C) are used in any appropriate ratio depending on the application of the prepolymer. For example, when obtaining a prepolymer for a cured product to be used as an insulating layer of a circuit board, the ratio of 0.80 to 1.83 moles of silane oligomer (B) and 0.53 to 4.30 moles of TMOS / TEOS (C) can be used per mole of polydimethylsiloxane (A). Furthermore, when obtaining a prepolymer for use as an adhesive, the ratio of 1.61 to 3.70 moles of silane oligomer (B) and 1.08 to 9.50 moles, preferably 1.08 to 8.55 moles of TMOS / TEOS (C) can be used per mole of polydimethylsiloxane (A).

[0010] A-1. Polydimethylsiloxane (A) Having Silanol Groups at Both Terminals As the polydimethylsiloxane (A) having silanol groups at both terminals, any appropriate polydimethylsiloxane (PDMS) having silanol groups at both terminals can be used. For example, the molecular chain may be linear or branched. Furthermore, it may have two or more silanol groups at its terminals, and may further have any appropriate reactive functional group. Preferably, a polydimethylsiloxane having a linear molecular chain and silanol groups at both terminals is used. As described above, the silane compound (D) has a fluoroalkyl group. Fluoroalkyl groups have significant steric hindrance, which can make synthesis difficult. By using a polydimethylsiloxane (A) having a linear molecular chain, the reaction with the silane compound (D) having a fluoroalkyl group can be carried out smoothly, and the desired organopolysiloxane prepolymer can be obtained more efficiently. Specifically, a polydimethylsiloxane (A) represented by the following formula (1) can be preferably used. H-(O-Si(CH ３ ) ２ ) ｍ —OH (1) (wherein m represents an integer of 70 to 900).

[0011] m is preferably an integer of 70 to 900, more preferably an integer of 100 to 850. m may be an integer in the range in which the number average molecular weight (Mn) falls within the above range, that is, 134 to 810.

[0012] The number average molecular weight (Mn) of the polydimethylsiloxane (A) having 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 of the polydimethylsiloxane (A) is within the above range, compatibility with other raw materials can be improved.

[0013] The weight-average molecular weight (Mw) of the polydimethylsiloxane (A) having 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. When the weight-average molecular weight of the polydimethylsiloxane (A) is within the above range, the solution used for 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 the polydimethylsiloxane (A) is preferably 1.3 or more, more preferably 1.5 or more, and even more preferably 1.75 or more. When the Mw / Mn of the polydimethylsiloxane (A) is within the above range, the mechanical strength of the resulting cured product can be improved. Furthermore, Mw / Mn is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. When the Mw / Mn is within the above range, the transparency of the resulting cured product can be improved. When the Mw / Mn is within the above range, the strength of the resulting cured product of the prepolymer is improved, and when used as an adhesive, the adhesive strength can be improved.

[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 polystyrene-equivalent molecular weights obtained by gel permeation chromatography (GPC) using polystyrene as a standard sample.

[0016] A-2. Silane oligomers having an alkoxy group, complete or partial hydrolysates of silane oligomers, and condensates of oligomers (B) Any suitable silane oligomer having an alkoxy group can be used as the silane oligomer (B) having an alkoxy group. The silane oligomer (B) having an alkoxy group is typically represented by formula (2). The silane oligomers having an alkoxy group (B) may be used alone or in combination of two or more. R １ O-(Si(OR ２ ) ２ -O) ｎ -R ３ (2) (In formula (2), R １ , R ２ , and R ３ each independently represents an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 2 or more).

[0017] R １ ~R ３ are each independently an alkyl group having 1 to 3 carbon atoms, preferably a methyl group or an ethyl group. n is an integer of 2 or more, preferably an integer of 3 or more. In practical terms, n may be an integer of 10 or less. In one embodiment, n is preferably an integer of 4 to 10. In one embodiment, the silane oligomer (B) having an alkoxy group is １ ~R ３are each independently a methyl group or an ethyl group, i.e., the alkoxy group may be a tetramer to decamer in which the alkoxy group is a methoxy group or an ethoxy group. Furthermore, if the alkoxy-containing silane oligomer (B) is linear, a decrease in reactivity due to steric hindrance can be suppressed. Similarly to the alkoxy-containing silane oligomer (B), a complete or partial hydrolyzate of an alkoxy-containing silane oligomer and a condensate of an alkoxy-containing silane oligomer can be used. The inclusion of these can extend the pot life of the composition before curing and improve storage stability. The complete or partial hydrolyzate of an alkoxy-containing silane oligomer and the condensate of an alkoxy-containing silane oligomer may be used alone or in combination of two or more.

[0018] A-3. Tetramethoxysilane and tetraethoxysilane (C) TMOS / TEOS (C) may be tetramethoxysilane alone, tetraethoxysilane alone, or a combination of tetramethoxysilane and tetraethoxysilane. Furthermore, the TMOS / TEOS (C) may be a combination having the same alkoxy group as the silane oligomer (B) having an alkoxy group, i.e., 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 a combination having different alkoxy groups.

[0019] Preferably, TMOS or TEOS is used in combination with a silane oligomer (B) having an alkoxy group and one having a different alkoxy group. Combinations of different alkoxy groups can produce prepolymers having alkoxy groups with different reaction temperatures when reacting with hydroxyl groups. In such prepolymers, the alkoxy groups with a lower reaction temperature can first react with a curing agent (e.g., an oligomer) to crosslink the prepolymer. The alkoxy groups with a higher reaction temperature then react to produce a cured product. Therefore, the prepolymer can be crosslinked at a lower temperature. Furthermore, for example, when a composition containing the prepolymer is used as an adhesive, the alkoxy groups with a higher reaction temperature selectively react at the interface with the adherend, further improving adhesion. More specifically, the methoxy groups can react with both terminal silanol groups of the polydimethylsiloxane (A) during the synthesis of the prepolymer. Furthermore, the ethoxy groups can react with the adherend during the curing reaction when the composition containing the prepolymer is used as a cured product, or when it is used as an adhesive or the like to be applied and bonded. In the case of a combination containing different alkoxy groups, i.e., a combination containing methoxy or ethoxy groups, synthesizing the prepolymer at a temperature at which the methoxy groups are more reactive than the ethoxy groups allows the methoxy groups to react selectively with the terminal silanol groups of the polydimethylsiloxane (A), leaving the ethoxy groups in the prepolymer. These ethoxy groups (i.e., free ethoxy groups) react with hydroxyl groups on the surface of the bonded material during the curing process for bonding with the adhesive, and with silanol groups that have been hydrolyzed from the methoxy groups to form hydroxyl groups, further accelerating the curing reaction.

[0020] In the TMOS / TEOS (C), the molar ratio of the alkoxy group-containing silane oligomer (B) to the TMOS / TEOS (C) is 0.25 mol to 5.59 mol, preferably 0.26 mol to 5 mol, more preferably 0.28 mol to 4.5 mol, and even more preferably 0.3 mol to 4.0 mol per 1 mol of the alkoxy group-containing silane oligomer (B). When the content ratio of the alkoxy group-containing silane oligomer (B) to the TMOS / TEOS (C) is within the above range, a prepolymer can be obtained that can be used to prepare a composition with a long pot life and excellent handleability. Furthermore, the adhesiveness and low dielectric properties of a composition using the obtained prepolymer can be improved.

[0021] A-4. Silane Compound (D) Having a Fluoroalkyl Group As the silane compound (D) having a fluoroalkyl group, any appropriate silane compound having a fluoroalkyl group can be used. By using the silane compound (D) having a fluoroalkyl group, the low dielectric properties of the obtained prepolymer can be improved. As the silane compound having a fluoroalkyl group, a silane compound represented by formula (3) is preferably used. The silane compound (D) having a fluoroalkyl group may be used alone or in combination of two or more. CF ３ (CF ２ ) ｏ (CH ２ ) ｐ -Si-(OR ４ ) ３ (3) (In formula (3), o represents an integer of 1 or more, p represents an integer of 1 or more, the sum of o and p is an integer of 5 to 8, and R ４ represents an alkyl group having 1 to 6 carbon atoms).

[0022] o represents an integer of 1 or greater, preferably an integer of 2 or greater. o is also preferably an integer of 6 or less. p represents an integer of 1 or greater, preferably an integer of 2 or greater. The sum of o and p is an integer of 5 to 8, preferably 6 or 7.

[0023] R ４ represents an alkyl group having 1 to 3 carbon atoms, preferably a methyl group or an ethyl group, and more preferably a methyl group.

[0024] Specific examples of the silane compound (D) having a fluoroalkyl group include triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane and trimethoxy(1H,1H,2H,2H-nonafluorohexyl)silane.

[0025] The fluoroalkyl group-containing silane compound (D) can be used in any appropriate amount depending on the amount of fluorine atoms to be introduced into the prepolymer, and the amount of the fluoroalkyl group-containing silane compound (D) is preferably 0.5 to 5 moles, more preferably 1 to 4 moles, per mole of the polydimethylsiloxane (A).

[0026] A-5. Organometallic Compounds Any other appropriate components may be further used in the condensation of the prepolymer of the present embodiment. Preferably, an organometallic compound is used as a condensation catalyst. Examples of organometallic compounds include tin (Sn)-based catalysts such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin bisacetylacetonate, dibutyltin dimaleate, and tin octoate; titanium (Ti)-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate; aluminum (Al)-based catalysts such as triisopropylaluminate; 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 bismuth tris(2-ethylhexanoate) or bismuth tris(neodecanoate). Sn-based catalysts are preferred because they are highly reactive and can effectively promote condensation reactions even with small amounts, and there is little risk of the cured product, if left behind, suffering from reduced heat resistance, coloration, etc. The organometallic compounds may be used alone or in combination of two or more.

[0027] The content of the organometallic compound is preferably 500 ppm or less, more preferably 300 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less, based on the solid content. The content of the organometallic compound is preferably 1 ppm or more based on the solid content.

[0028] A-6. Prepolymer Preparation Method The prepolymer of an embodiment 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 fluoroalkyl group by any appropriate method. Preferably, in the presence of an organometallic compound serving 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 involving dehydration or dealcoholization. Next, a silane compound (D) having a fluoroalkyl group is added to the reaction solution after the condensation reaction, and further condensation reaction is carried out, thereby obtaining the prepolymer of an embodiment of the present invention.

[0029] The reaction temperature may be set to any appropriate value, preferably 40°C to 140°C, more preferably 60°C to 120°C. The reaction time may be set to any appropriate value, preferably 0.5 hours to 24 hours, more preferably 6 hours to 20 hours.

[0030] B. Silicone Composition The silicone composition according to an embodiment of the present invention comprises the prepolymer according to the embodiment of the present invention and a curing agent. As described above, the prepolymer according to an embodiment of the present invention can provide a cured product having excellent heat resistance and low dielectric properties. Therefore, it can be suitably used for forming an encapsulant for semiconductor elements and an interlayer insulating film. Furthermore, a silicone composition using the prepolymer according to an embodiment of the present invention can also exhibit excellent adhesive properties. Therefore, it can be used as an adhesive composition, and can also be suitably used as an insulating adhesive.

[0031] B-1. Curing Agent Any appropriate curing agent can be used as the curing agent contained in the silicone resin composition of the present embodiment. Examples include the organometallic compounds exemplified in Section A-5 above. Preferred organometallic compounds include organometallic salts such as zinc octoate, oxozirconium octoate, tin octoate, and dibutyltin dimaleate. Use of these compounds can lower the curing temperature of the composition, improving the production efficiency of the cured product. Furthermore, a thicker cured product can be obtained. These organometallic salts may be commercially available. Examples of commercially available products include Nikka Octix (registered trademark) Zinc and Nikka Octix (registered trademark) Zirconium, both manufactured by Nippon Chemical Industry Co., Ltd. Only one type of organometallic compound may be used, or two or more types may be used in combination.

[0032] The organometallic salt can be used in any appropriate content, preferably 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, relative to 100 parts by weight of the prepolymer. When the content of the organometallic salt is within the above range, the curing reaction of the prepolymer can be appropriately promoted.

[0033] As the curing agent, it is preferable to use a combination of an organometallic compound and a tetraalkoxysilane oligomer. By using a combination of an organometallic compound and a tetraalkoxysilane oligomer, it is possible to improve the crosslink density and obtain a cured product with higher hardness. It is also possible to reduce the tackiness of the surface of the obtained cured product. It is also possible to coordinate a large number of alkoxy groups, which can improve the adhesiveness of the composition and the water resistance of the obtained cured product. Specific examples of tetraalkoxysilane oligomers include tetraethoxysilane oligomers. Only one type of tetraalkoxysilane oligomer may be used, or two or more types may be used in combination.

[0034] The tetraalkoxysilane oligomer can be used in any appropriate content. 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 appropriately cured.

[0035] B-2. Other Additives The silicone composition according to an embodiment of the present invention may further contain any other appropriate additives other than the prepolymer and the curing agent. Any appropriate material may be used as the additive depending on the intended use of the silicone composition. Examples include organic solvents, mold release agents, colorants, viscosity modifiers, polymerization inhibitors, curing accelerators, antifoaming agents, dispersants, heat stabilizers, surfactants, lubricants, antistatic agents, UV absorbers, bluing agents, fillers, thermoplastic resins, and the like. Only one type of additive may be used, or two or more types may be used in combination. The additives may be used in any appropriate amount.

[0036] The silicone composition can be prepared by any suitable method, for example, by adding a curing agent and optional additives to a solution obtained by a condensation reaction of an organopolysiloxane prepolymer and mixing the mixture.

[0037] C. Cured Product The cured product of the embodiment of the present invention is obtained by curing the above-described prepolymer. Any appropriate curing agent can be used as the curing agent. As described above, the cured product of the embodiment of the present invention has excellent heat resistance, low dielectric properties, and may also have excellent adhesive properties. Therefore, it can be suitably used in applications requiring heat resistance and insulating properties, such as adhesive compositions for semiconductor encapsulation and insulating adhesives.

[0038] In one embodiment, a cured product 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 prepolymer-containing composition to cure without forming a film on the surface. When cured at a temperature lower than 120°C, the curing agent may selectively crosslink on the surface of the prepolymer-containing composition, leaving the interior uncured. As described above, the cured product of an embodiment of the present invention has excellent heat resistance and can be inhibited from thermal decomposition even when heated at high temperatures for a long period of time.

[0039] The cured product preferably has a relative dielectric constant at 10 GHz of 3 or less, more preferably 2.8 or less, and even more preferably 2.6 or less. The lower the relative dielectric constant, the more preferable, for example, 2.3 or more. If the relative dielectric constant is within the above range, the product can be suitably used in applications requiring low dielectric properties.

[0040] The weight loss rate of the cured product after being kept at 200°C for 100 hours is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less. If the weight loss rate is within the above range, it can be suitably used in applications where heat resistance is required. The weight loss rate can be calculated from the change in weight before and after heating using the following formula: Weight loss rate = (W1 - W2) / W1 x 100 (%) W1: Weight (parts by weight) of the cured product before heating at 200°C for 100 hours W2: Weight (parts by weight) of the cured product after heating at 200°C for 100 hours

[0041] D. Applications The prepolymers of the present invention can provide cured products with excellent heat resistance and low dielectric properties. Furthermore, the use of the prepolymers of the present invention can provide cured products with excellent adhesive properties. Therefore, the prepolymers of the present invention are suitable for applications requiring such properties. Specifically, the prepolymers of the present invention can be used in adhesive compositions such as semiconductor encapsulants, insulating adhesives, and adhesives requiring transparency.

[0042] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0043] Example 1 A four-necked reactor equipped with a stirrer and a thermometer was filled with nitrogen gas. 85.31 wt% of a polydimethylsiloxane (A) having silanol groups at both ends (product name "PLY2-7630" manufactured by Nusil Technology, number-average molecular weight Mn: 27,100, weight-average molecular weight Mw: 59,902, molecular weight distribution index Mw / Mn: 2.21) and 9.33 wt% of a mixture of a silane oligomer (B) having alkoxy groups, tetramethoxysilane, and tetraethoxysilane (C) (product name "SilBond40" manufactured by Evonik, a mixture of tetraethoxysilane tetramers to decamers and tetraethoxysilane, tetraethoxysilane content: 25 wt%) were introduced into the reactor and stirred until homogeneous. Next, 8 ppm of a condensation catalyst (dibutyltin dilaurate, manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was allowed to react at 85°C for 6 hours. This mixture was then allowed to cool naturally, yielding Solution A. Next, 5.86 wt% of a silane compound (D) having a fluoroalkylene group (manufactured by Tokyo Chemical Industry Co., Ltd., product name "T3560", a silane compound having one perfluoroalkyl group and three methoxy groups (trimethoxy(1H,1H,2H,2H-tridecafluoro-n-octyl)silane)) was added to Solution A, and the mixture was allowed to react at 100°C for 3 hours. This mixture was then allowed to cool naturally, yielding an organopolysiloxane prepolymer. The number-average molecular weight Mn and weight-average molecular weight Mw were measured by the following method. The weight-average molecular weight Mw and number-average molecular weight Mn were each measured by gel permeation chromatography (GPC), and the ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn was taken as the molecular weight distribution index. Polystyrene was used as a standard sample, and measurements were made as converted molecular weights. The measurement of the molecular weight in terms of polystyrene by the GPC method was carried out under the following measurement conditions.Measuring equipment: Tosoh Corporation, product name: GPC HLC-8230PC Columns with Mn of 30,000 or less: TSKgel guardColumn Super HZ-H, TSKgel Super HZM-M x 2 Columns with Mn of 30,000 or more (including those with Mn of 50,000 or more): TSKgel guardColumn Super MP(HZ)-N, TSKgel Multipore HZ-N x 3 Oven temperature: 40°C Eluent: tetrahydrofuran (THF) (1 ml / min) Standard sample: polystyrene Sample preparation: THF solvent containing 0.2 wt% 2,6-di-tert-butyl-t-phenol (BHT) was used, and the sample was allowed to stand at room temperature to dissolve. Correction: The deviation of the GPC peaks between the calibration curve measurement and the sample measurement was corrected, and the molecular weight was measured.

[0044] Example 2 An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 86.31% by weight of component (A) was used, and a mixture of 4.17% by weight of SilBond 40 and 4.17% by weight of KC-89S (a low-polymerization methyl oligomer of tetramethoxysilane, manufactured by Shin-Etsu Silicones Co., Ltd.) was used as the mixture of components (B) and (C).

[0045] Example 3: 87.31% by weight of component (A) was used, and Ethyl Silicate 40 (manufactured by Colcoat Co., Ltd., Si ５ O ４ (OEt) １２ An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 8.40% by weight of (average pentamer) was used, and 0.93% by weight of tetraethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd., product name "T0100") was used as component (C).

[0046] Example 4 An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 84.41% by weight of component (A) was used, 6.50% by weight of SilBond 40 was used as the mixture of components (B) and (C), 3.25% by weight of tetraethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd., product name "T0100") was used as component (C), and 5.83% by weight of component (D) was used.

[0047] Example 5 An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 85.13 wt% of component (A) was used, 4.68 wt% of KC-89S was used as component (B), 4.3 wt% of tetramethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd., product name "T0588") was used as component (C), and 5.88 wt% of component (D) was used.

[0048] Comparative Example 1 An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 83.04% by weight of component (A) was used, 8.92% by weight of ethyl silicate 40 was used as component (B), 3.25% by weight of tetraethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd., product name "T0100") was used as component (C), and 5.17% by weight of T2860 (manufactured by Tokyo Chemical Industry Co., Ltd., triethoxy(1H,1H,2H,2H-nonafluorohexyl)silane) was used as the silane compound (D) having a fluoroalkyl group.

[0049] Comparative Example 2 An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 90.31% by weight of component (A) was used, 9.33% by weight of KC-89S was used as component (B), and the fluoroalkyl group-containing silane compound (D) was not used.

[0050] Comparative Example 3 An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 91.31% by weight of component (A) was used, 9.33% by weight of Ethyl Silicate 40 was used as the mixture of components (B) and (C), and the fluoroalkyl group-containing silane compound (D) was not used.

[0051] Comparative Example 4 An organopolysiloxane prepolymer was obtained in the same manner as in Example 1, except that 91.31% by weight of component (A) was used, 9.48% by weight of Silbond 40 was used as the mixture of components (B) and (C), 4.31% by weight of tetraethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd., product name "T0100") was used as component (C), and the silane compound (D) having a fluoroalkyl group was not used.

[0052] [Production Example 1] Preparation of curing agent 5 parts by weight of TEOS oligomer (pentamer to decamer) (manufactured by Evonik Corporation, product name "SilBond50"), 25 parts by weight of Nikka Octix (registered trademark) Zirconium (manufactured by Nippon Chemical Industry Co., Ltd.), and 16 parts by weight of Nikka Octix (registered trademark) Zinc (manufactured by Nippon Chemical Industry Co., Ltd.) were mixed to obtain a curing agent.

[0053] [Evaluation] The organopolysiloxane prepolymers obtained in the Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

[0054] 1. Pot Life The organopolysiloxane prepolymers obtained in the Examples and Comparative Examples were measured at 25°C using an E-type viscometer (manufactured by TOKI SANGYO, product name "VISCOMETER TV-35") to determine their viscosity at the start of measurement and after storage at 25°C for one week. The viscosity increase rate was calculated from each viscosity value using the following formula: Viscosity increase rate (%) = {(viscosity after one week (Pa s)) - (viscosity at the start of measurement (Pa s))} / (viscosity at the start of measurement (Pa s)) × 100 ◎ (Best): Viscosity increase of 5% or less in one week ○ (Good): Viscosity increase of more than 5% but not more than 10% in one week △ (Fair): Viscosity of the solution after synthesis was 5 Pa S or more (evaluation of the cured product was not performed) × (Romance for improvement): Gelation occurred after one week of storage (evaluation of the cured product was not performed)

[0055] 2. Three parts by weight of the curing agent prepared in Production Example 1 was added to 100 parts by weight of the solids content of the organopolysiloxane prepolymer obtained in the adhesiveness examples or comparative examples, and the mixture was stirred and degassed. A film was then formed on a Teflon (registered trademark) tray 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 Corporation, aluminum plate material, thickness 0.3 mm, size 2 cm × 4 cm) to a coating thickness of 80 μm. The plate was then preheated at 60°C for 30 minutes and then heated at 200°C for 3 hours to cure the silicone composition, thereby obtaining a sample. Similarly, the silicone composition was also applied to copper foil (manufactured by AS ONE Corporation, copper plate material, thickness 50 μm, size 2 cm × 4 cm) to obtain a sample. The strength at break of these samples was measured using an autograph (manufactured by Shimadzu Corporation, product name "AG-X 20kN or AG-X 1kN"), and the strength at break values ​​(N / cm ２ ) was taken as the tensile shear adhesive strength. An appropriate autograph was used depending on the tensile shear adhesive strength. Measurements were carried out for three samples and the average value was calculated. The adhesive strength values ​​obtained were evaluated according to the following criteria: ◎ (best): Adhered to both aluminum plate and copper foil, with a tensile shear adhesive strength of 10 N / cm ２ ◯ (Good): Adheres to both aluminum plate and copper foil, and the tensile shear adhesive strength is 10 N / cm or more ２ △ (Fair): When adhered to an aluminum plate or copper foil, the tensile shear adhesive strength is less than 10 N / cm ２ Less than × (room for improvement): Does not adhere to aluminum plate or copper foil

[0056] 3. Dielectric Constant: 3 parts by weight of the curing agent prepared in Production Example 1 was added to 100 parts by weight of the solids content of the organopolysiloxane prepolymer obtained in the Examples or Comparative Examples, and the mixture was stirred and degassed to obtain a silicone composition. The resulting silicone composition was then placed in a Teflon (registered trademark) tray and formed into a film with a thickness of 0.4 mm. The silicone composition in the Teflon (registered trademark) tray was then preheated at 60°C for 30 minutes and then heated at 200°C for 3 hours to cure the silicone composition. The cured silicone composition was then cut into a width of 4 mm and a length of 10 cm to prepare a sample. The dielectric constant of the sample was measured at a measurement frequency of 10 GHz using a cavity resonator dielectric constant measuring device (manufactured by AET Corporation, product name "ADMS1Nc1"). ◎ (Best): Dielectric constant of 2.6 or less; ◯ (Good): Dielectric constant of 3 or less; △ (Fair): Dielectric constant exceeding 3; × (Unacceptable): Film formation was difficult, or the film strength was weak, making sampling difficult.

[0057] 4. Heat Resistance: 3 parts by weight of the curing agent prepared in Production Example 1 was added to 100 parts by weight of the solids content of the organopolysiloxane prepolymer obtained in the Examples or Comparative Examples, and the mixture was stirred and degassed. A film was then formed on a Teflon (registered trademark) tray to obtain a silicone composition. 5 g of the silicone composition was added to an aluminum cup, and the aluminum cup was weighed. The aluminum cup was then placed in an oven at 200°C and held there for 200 hours. The aluminum cup was then removed from the oven and allowed to cool to room temperature. The aluminum cup was then weighed, and the weight loss rate was calculated from the weights before and after heating using the following formula: Weight loss rate = (W1 - W2) / W1 x 100 (%) W1: Weight (parts by weight) of the silicone composition and aluminum cup before heating at 200°C for 100 hours W2: Weight (parts by weight) of the silicone composition and aluminum cup after heating at 200°C for 100 hours ◯ (Good): Weight loss of 5% or less after 100 hours of storage at 200°C △ (Fair): Weight loss of more than 5% but not more than 10% after 100 hours of storage at 200°C × (Fail): Appearance defect such as cracks or weight loss of more than 10% after 100 hours of storage at 200°C

[0058]

[0059] The cured products using the organopolysiloxane prepolymers of the examples of the present invention had excellent heat resistance and low dielectric properties, and also had excellent adhesive properties.

[0060] The organopolysiloxane prepolymer of the present invention can be suitably used as a semiconductor encapsulant, insulating adhesive, and the like.

Claims

1. An organopolysiloxane prepolymer obtained by condensing (A) a polydimethylsiloxane having silanol groups at both ends, (B) at least one member selected from the group consisting of a silane oligomer having an alkoxy group, a complete or partial hydrolyzate of the silane oligomer, and a condensate of the oligomer, (C) at least one member selected from the group consisting of tetramethoxysilane and tetraethoxysilane, and (D) a silane compound having a fluoroalkyl group, wherein the molar ratio of the silane oligomer having an alkoxy group (B) to the at least one member selected from the group consisting of tetramethoxysilane and tetraethoxysilane (C) is 0.25 to 5.59 moles of the at least one member selected from the group consisting of tetramethoxysilane and tetraethoxysilane per mole of the silane oligomer having an alkoxy group (B).

2. The organopolysiloxane prepolymer according to claim 1, wherein the at least one member (B) selected from the group consisting of silane oligomers having alkoxy groups, complete or partial hydrolysates of the silane oligomers, and condensates of the oligomers is a tetramer to a decamer, and the alkoxy groups are methoxy groups or ethoxy groups.

3. A silicone composition comprising the organopolysiloxane prepolymer according to claim 1 or 2 and a curing agent.

4. The silicone composition according to claim 3, wherein the curing agent comprises a tetraalkoxysilane oligomer and an organic acid metal salt.

5. A sealing material comprising the organopolysiloxane prepolymer according to claim 1 or 2.

6. An adhesive composition comprising the organopolysiloxane prepolymer of claim 1 or 2.

7. A cured product of the organopolysiloxane prepolymer according to claim 1 or 2.

8. The cured product according to claim 7, having a relative dielectric constant of 3 or less at 10 GHz.

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