Recyclable curable silicone resin composition

Abstract

Provided is a silicone resin composition that is recyclable and that can be easily liquefied through application of heat.　This curable silicone resin composition contains (A) a furanyl group-containing organopolysiloxane having a number average molecular weight of 500-40,000, and (B) a maleimide group-containing organopolysiloxane having a number average molecular weight of 500-40,000. According to the present invention, a curable silicone resin composition recycling method comprises a step for heating a cured product of the curable silicone resin composition at 130°C or higher.

Description

[Technical Field]

[0001] This invention relates to a recyclable curable silicone resin composition. [Background technology]

[0002] Silicone resins are used in a variety of fields, including sealing for buildings and coatings for automobile bodies. However, because silicone resins are thermosetting resins, dismantling and recycling them through heating is difficult. Depolymerization by main chain cracking using acids or bases, or by exposing them to ultra-high temperatures exceeding 400°C, is possible. However, recycling is difficult due to problems with wastewater treatment associated with the neutralization process and the energy required for repolymerization.

[0003] Patent Document 1 discloses an attempt to impart disassembly properties to a silicone resin by incorporating thermally expandable microcapsules. However, it does not mention the recycling of the silicone resin after disassembly. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-123943 [Overview of the project] [Problems that the invention aims to solve]

[0005] Therefore, the present invention aims to provide a silicone resin composition that can be easily liquefied by heating and is recyclable. [Means for solving the problem]

[0006] In order to solve the above problems, the inventors conducted extensive research and, as a result, discovered that a silicone resin composition containing a furanyl group-containing organopolysiloxane and a maleimide group-containing organopolysiloxane is a recyclable, curable silicone resin composition that liquefies at temperatures of 130°C or higher, thus completing the present invention.

[0007] In other words, the present invention provides the following recyclable curable silicone resin composition.

[0008] [1] The following components (A) and (B); (A) Organopolysiloxanes containing furanyl groups, represented by the following formula (1), with a number average molecular weight of 500 to 40,000. [ka] (In formula (1), R 1 R is independently selected from the group consisting of a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, and a furanyl group represented by the following formulas (2) and (3), and R in one molecule 1 Two or more of these are furanyl groups represented by the following formula (2) or (3): a is a number greater than or equal to 2, b is a number greater than or equal to 0, c is a number greater than or equal to 0, and d is a number greater than or equal to 0, and 2 ≤ a + b + c + d ≤ 500. [ka] (In equations (2) and (3), R 2 and R 3 Each of these is independently either a hydrogen atom or a linear alkyl group having 1 to 10 carbon atoms. (Dashed lines indicate bonding.) (B) Maleimide group-containing organopolysiloxanes with a number average molecular weight of 500 to 40,000, represented by the following formula (4), [ka] (In formula (4), R 4is, independently, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a maleimide group represented by the following formula (5), and R in one molecule 4 Two or more of them are maleimide groups represented by the following formula (5). e is a number of 2 or more, f is a number of 0 or more, g is a number of 0 or more, h is a number of 0 or more, and 2 ≤ e + f + g + h ≤ 500.) [Chemical formula] (In formula (5), R 5 is, independently, a hydrogen atom or a methyl group. The broken line indicates a bond.) A curable silicone resin composition containing [2] The curable silicone resin composition according to [1], wherein both or either one of d in formula (1) and h in formula (4) is 0. [3] The curable silicone resin composition according to [1] or [2], wherein both or either one of c in formula (1) and g in formula (4) is 0. [4] The curable silicone resin composition according to any one of [1] to [3], wherein c, d in formula (1) and g, h in formula (4) are all 0. [5] A recycling method of a curable silicone resin composition, comprising a step of heating a cured product of the curable silicone resin composition according to any one of [1] to [4] to 130°C or higher. [Advantages of the Invention]

[0009] According to the present invention, a recyclable curable silicone resin composition that liquefies when heated at a temperature of 130°C or higher can be provided. Further, this silicone resin composition can be cured at a relatively low temperature of 0°C or higher and 100°C or lower. Further, the curable silicone resin composition of the present invention is useful for applications such as adhesives, adhesives, sealants, coating agents, and the like. [Modes for Carrying Out the Invention]

[0010] Hereinafter, the present invention will be described in detail.

[0011] [(A) Furanyl group-containing organopolysiloxane] The furanyl group-containing organopolysiloxane with a number average molecular weight of 500 to 40,000, which is the component (A) of the present invention, is represented by the following formula (1). [Chemical formula]

[0012] In the above formula (1), R 1 is independently selected from the group consisting of a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, and a furanyl group represented by the following formulas (2) and (3), and two or more of R 1 in one molecule are furanyl groups represented by the following formula (2) or (3). a is a number of 2 or more, b is a number of 0 or more, c is a number of 0 or more, d is a number of 0 or more, and 2 ≤ a + b + c + d ≤ 500. [Chemical formula]

[0013] In the above formulas (2) and (3), R 2 and R 3 are each independently a hydrogen atom or a linear alkyl group having 1 to 10 carbon atoms. The dashed line indicates a bond.

[0014] In the above formula (1), R 1 is independently selected from the group consisting of a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, and the furanyl group represented by the above formulas (2) and (3). In formula (1), R 1Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms represented by include alkyl groups such as methyl, ethyl, propyl, and butyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; and aryl groups such as phenyl and tolyl groups. Examples of alkoxy groups having 1 to 4 carbon atoms include methoxy, ethoxy, propoxy, and butoxy groups. R in one molecule 1 Two or more of these, preferably two to four, are furanyl groups represented by formula (2) or (3) above. Other preferred groups include alkyl groups, cycloalkyl groups, and aryl groups, with methyl groups and phenyl groups being more preferred.

[0015] In equations (2) and (3) above, R 2 and R 3 Each is independently a hydrogen atom or a linear alkyl group having 1 to 10 carbon atoms. In formulas (2) and (3), R 2 or R 3 Examples of linear alkyl groups having 1 to 10 carbon atoms represented by include methyl, ethyl, propyl, and butyl groups. Among them, R 2 and R 3 A hydrogen atom or a methyl group is preferred as the element.

[0016] In formula (1) above, a is 2 or greater, preferably a number from 2 to 12; b is 0 or greater, preferably a number from 1 to 498, more preferably a number from 5 to 300; c is 0 or greater, preferably a number from 0 to 10, more preferably 0; d is 0 or greater, preferably a number from 0 to 5, more preferably 0; and 2 ≤ a + b + c + d ≤ 500, preferably 2 ≤ a + b + c + d ≤ 300, more preferably 3 ≤ a + b + c + d ≤ 300, and even more preferably 4 ≤ a + b + c + d ≤ 150. If a + b + c + d is greater than 500, the viscosity of the furanyl group-containing organopolysiloxane may increase, which may result in poor workability.

[0017] The molecular weight of the furanyl group-containing organopolysiloxane of the present invention is 500 to 40,000 in number average molecular weight, preferably 1,000 to 20,000, and more preferably 1,000 to 10,000. If the molecular weight is less than 500, properties such as flexibility derived from (poly)siloxane may not be exhibited, and if it exceeds 40,000, the viscosity of the furanyl group-containing organopolysiloxane may increase, which may worsen workability, and is therefore undesirable.

[0018] In this invention, the number-average molecular weight is the value obtained by GPC (gel permeation chromatography) analysis using polystyrene as a standard substance under the following conditions (the same applies hereinafter).

[0019] [Measurement conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.6mL / min Detector: Differential refractive index detector (RI) Column: TSK Guardcolumn SuperH-H TSKgel SuperHM-N(6.0mmI.D.×15cm×1) TSKgel SuperH2500(6.0mmI.D.×15cm×1) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 50 μL (THF solution with a concentration of 0.3% by mass)

[0020] [(B) Maleimide group-containing organopolysiloxane] The maleimide group-containing organopolysiloxane, which is component (B) of the present invention, has a number-average molecular weight of 500 to 40,000 and is represented by the following formula (4). [ka]

[0021] In the above equation (4), R 4 R is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms or a maleimide group represented by the following formula (5), and R in one molecule4 Two or more of these, preferably 2 to 8, are maleimide groups represented by the following formula (5): e is a number greater than or equal to 2, f is a number greater than or equal to 0, g is a number greater than or equal to 0, and h is a number greater than or equal to 0, and 2 ≤ e + f + g + h ≤ 500. [ka]

[0022] In the above equation (5), R 5 These are independently either a hydrogen atom or a methyl group. Dashed lines indicate bonding.

[0023] In the above equation (4), R 4 R is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms or a maleimide group represented by the above formula (5), and R in one molecule 4 Two or more of these are maleimide groups represented by formula (5) above. In formula (4), R 4 Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms represented by include alkyl groups such as methyl, ethyl, propyl, and butyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; and aryl groups such as phenyl and tolyl groups. Among these, alkyl groups, cycloalkyl groups, and aryl groups are preferred, with methyl and phenyl groups being more preferred.

[0024] In the above equation (5), R 5 This is either a hydrogen atom or a methyl group. Of these, a hydrogen atom is preferred.

[0025] In formula (4) above, e is 2 or greater, preferably a number from 2 to 12; f is 0 or greater, preferably a number from 1 to 498, more preferably a number from 5 to 300; g is 0 or greater, preferably a number from 0 to 10, more preferably 0; h is 0 or greater, preferably a number from 0 to 5, more preferably 0; and 2 ≤ e + f + g + h ≤ 500, preferably 2 ≤ e + f + g + h ≤ 300, more preferably 3 ≤ e + f + g + h ≤ 300, and even more preferably 4 ≤ e + f + g + h ≤ 150. If e + f + g + h is greater than 500, the viscosity of the maleimide group-containing organopolysiloxane may increase, resulting in poor workability.

[0026] The molecular weight of the maleimide group-containing organopolysiloxane of the present invention is 500 to 40,000 in number average molecular weight, preferably 1,000 to 20,000, and more preferably 1,000 to 10,000. If the molecular weight is less than 500, properties such as flexibility derived from (poly)siloxane may not be exhibited, and if it exceeds 40,000, the viscosity of the maleimide group-containing organopolysiloxane may increase, resulting in poor workability.

[0027] The amount of component (B) is preferably 1 to 2 equivalents of maleimide groups in component (B) per 1 equivalent of furanyl groups in component (A), and more preferably 1.1 to 1.5 equivalents. In the composition of the present invention, components (A) and (B) are preferably present in amounts of 60 to 100% by mass, more preferably in amounts of 80 to 100% by mass, and even more preferably in amounts of 90 to 100% by mass.

[0028] [Other ingredients] The curable silicone resin composition of the present invention may contain components other than those listed above, as long as they do not impair the effects of the present invention. Examples of components other than those listed above include binders such as silica powder and metal fillers.

[0029] [Method for producing a curable silicone resin composition] As a method for producing the recyclable curable silicone resin composition of the present invention, known methods for mixing liquid substances can be used. In particular, since (A) a furanyl group-containing organopolysiloxane and (B) a maleimide group-containing organopolysiloxane have excellent compatibility with each other, a uniform composition can be obtained by simply mixing them at room temperature (25°C). When adding components other than (A) furanyl group-containing organopolysiloxane and (B) maleimide group-containing organopolysiloxane to the composition of the present invention, it is preferable to pre-disperse the components in components (A) and / or (B) by known methods and then simply mix them at room temperature (25°C).

[0030] [Method for curing a curable silicone resin composition] The curable silicone resin composition of the present invention is preferably cured at a temperature of 0°C to 100°C, preferably 15°C to 80°C, for 12 to 96 hours, preferably 24 to 72 hours.

[0031] [Recycling methods for curing silicone resin] The method for recycling the cured silicone resin of the curable silicone resin composition of the present invention comprises a step of heating at a temperature of 130°C or higher, preferably 130°C to 160°C, for 3 to 30 minutes, preferably 3 to 10 minutes. This heating step causes the cured product of the curable silicone resin composition of the present invention to liquefy, and the liquefied curable silicone resin composition can be cured again under the above curing conditions and recycled. [Examples]

[0032] The present invention will be described in more detail below with reference to examples, but the scope of the present invention shall not be limited by the following specific examples.

[0033] <Example 1> 3.79 g of a furanyl group-containing organopolysiloxane (number average molecular weight 7,570) represented by formula (6) below and 2.58 g of a maleimide group-containing organopolysiloxane (number average molecular weight 6,880) represented by formula (7) below were stirred at room temperature (25°C) for 5 minutes. The resulting silicone resin composition was left to stand at room temperature for 3 days to cure. When the cured silicone resin composition was heated in an oven at 150°C for 5 minutes, it completely liquefied. The liquefied composition was left to stand again at room temperature for 3 days and cured again. [ka] [ka]

[0034] <Example 2> 3.84 g of a furanyl group-containing organopolysiloxane (number average molecular weight 7,680) represented by formula (8) below and 2.58 g of a maleimide group-containing organopolysiloxane (number average molecular weight 6,880) represented by formula (7) above were stirred at room temperature (25°C) for 5 minutes. The resulting silicone composition was allowed to stand at room temperature for 3 days to cure. When the cured silicone resin composition was heated in an oven at 150°C for 5 minutes, it completely liquefied. When the liquefied composition was allowed to stand again at room temperature for 3 days, it cured again. [ka]

[0035] <Example 3> 2.10 g of a furanyl group-containing organopolysiloxane (number average molecular weight 6,310) represented by formula (9) below and 2.58 g of a maleimide group-containing organopolysiloxane (number average molecular weight 6,880) represented by formula (7) above were stirred at room temperature (25°C) for 5 minutes. The resulting silicone composition was allowed to stand at room temperature for 3 days to cure. When the cured silicone resin composition was heated in a 150°C oven for 5 minutes, it completely liquefied. When the liquefied composition was allowed to stand again at room temperature for 3 days, it cured again. [ka]

[0036] <Example 4> 2.13 g of a furanyl group-containing organopolysiloxane (number average molecular weight 6,400) represented by formula (10) and 2.58 g of a maleimide group-containing organopolysiloxane (number average molecular weight 6,880) represented by formula (7) were stirred at room temperature (25°C) for 5 minutes. The resulting silicone composition was allowed to stand at room temperature for 3 days to cure. When the cured silicone resin composition was heated in an oven at 150°C for 5 minutes, it completely liquefied. When the liquefied composition was allowed to stand again at room temperature for 3 days, it cured again. [ka]

[0037] <Comparative Example 1> 0.3 g of a furanyl group-containing organopolysiloxane (number average molecular weight 290) represented by formula (11) and 2.58 g of a maleimide group-containing organopolysiloxane (number average molecular weight 6,880) represented by formula (7) were stirred at room temperature (25°C) for 5 minutes. The resulting silicone composition was left to stand at room temperature for 3 days, but it only thickened and did not harden. [ka]

Claims

1. The following components (A) and (B); (A) A furanyl group-containing organopolysiloxane having a number average molecular weight of 500 to 40,000, represented by the following formula (1), 【Chemistry 1】 (In formula (1), R 1 R is independently selected from the group consisting of a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, and a furanyl group represented by the following formulas (2) and (3), and R in one molecule 1 Two or more of these are furanyl groups represented by the following formula (2) or (3): a is a number greater than or equal to 2, b is a number greater than or equal to 0, c is a number greater than or equal to 0, and d is a number greater than or equal to 0, and 2 ≤ a + b + c + d ≤ 500. 【Chemistry 2】 (In equations (2) and (3), R 2 and R 3 Each of these is independently either a hydrogen atom or a linear alkyl group having 1 to 10 carbon atoms. (The dashed lines indicate bonding.) (B) Maleimide group-containing organopolysiloxanes having a number average molecular weight of 500 to 40,000, represented by the following formula (4), 【Transformation 3】 (In formula (4), R 4 R is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms or a maleimide group represented by the following formula (5), and R in one molecule 4 Two or more of these are maleimide groups represented by the following formula (5): e is a number greater than or equal to 2, f is a number greater than or equal to 0, g is a number greater than or equal to 0, and h is a number greater than or equal to 0, and 2 ≤ e + f + g + h ≤ 500. 【Chemistry 4】 (In formula (5), R 5 These are independently either a hydrogen atom or a methyl group. (Dashed lines indicate bonding.) A curable silicone resin composition containing [the specified ingredient].

2. The curable silicone resin composition according to claim 1, wherein both or either of d in formula (1) and h in formula (4) are 0.

3. The curable silicone resin composition according to claim 1, wherein both or either c in formula (1) and g in formula (4) are 0.

4. The curable silicone resin composition according to claim 1, wherein c and d in formula (1) and g and h in formula (4) are all 0.

5. A method for recycling a curable silicone resin composition, comprising the step of heating the cured product of the curable silicone resin composition according to any one of claims 1 to 4 to 130°C or higher.

Images