Method for producing (meth)acryloyl group-containing organopolysiloxane

Abstract

[Problem] The present invention aims to provide a novel transesterification production method whereby a (meth)acryloyl group-containing organopolysiloxane that is transparent and has a good external appearance can be obtained at reduced cost. [Solution] A production method for (meth)acryloyl group-containing organopolysiloxane that is characterized by including a step in which a hydroxyl group-containing organopolysiloxane (A) indicated by average formula (1) (in the formula, each R1 is independently a substituted or unsubstituted C1–10 monovalent hydrocarbon group, an alkoxy group, or a monovalent hydrocarbon group or a (poly) oxyalkylene alkyl group (hereinafter collectively referred to as a hydroxyl group-containing group) that has a hydroxyl group at a terminal thereof, at least one R1 is a hydroxyl group-containing group, a is an integer of at least 2, b is 0 or an integer, C is 0 or an integer, d is 0 or an integer, and 2 ≤ a + b + c + d ≤ 1, 000) is reacted, in the presence of component (C) and component (D), with a (meth) acrylic acid ester (B) represented by general formula (2) (in the formula, R2 is a hydrogen atom or a methyl group and R3 is a substituted or unsubstituted C1–5 linear or branched monovalent hydrocarbon group), in an amount that provides a molar ratio of 1 to 10 per 1 mole of the hydroxyl groups in component (A). Component (C) is a compound indicated by general formula (3), which is liquid at 20°C, provided in an amount whereby the molar ratio is 0.001 to 0.1 per mole of the hydroxyl groups in component (A). (3) Zr (OR4)4 (in the formula, R4 is a substituted or unsubstituted C1–10 linear or branched monovalent hydrocarbon group and may include a carbonyl group). Component (D) is a compound indicated by general formula (4) or (5), which is liquid at 20°C, provided in an amount that provides the molar ratio is 0.002 to 0.8 per mole of the hydroxyl groups in component (A) (in the formula, R5 and R6 each independently indicate a substituted or unsubstituted C1–6 monovalent hydrocarbon group) (in the formula, R7 indicates a substituted or unsubstituted C1–6 monovalent hydrocarbon group).

Description

[Technical Field]

[0001] The present invention relates to a method for producing a radically polymerizable organopolysiloxane. [Background technology]

[0002] The technique of applying energy to a liquid resin composition to cure it is a widespread technology and is used in many fields, such as for producing coatings and molded products. The energy required for this curing is heat or radiation such as ultraviolet light. In the case of heat curing, a heat-activated catalyst is added to the base resin, and a cured product is obtained by applying heat. In the case of radiation curing, a composition containing a photoinitiator that is activated by ultraviolet light or other radiation is cured by irradiating it with radiation.

[0003] Typical functional groups used in radiation curing include (meth)acryloyl groups, mercapto groups, and epoxy groups. (Meth)acryloyl groups form crosslinks through radical polymerization reactions, and mercapto groups undergo radical ene-thiol reactions in the presence of alkenyl groups. Epoxy groups undergo cationic polymerization in the presence of acids.

[0004] Various resins are used for this type of radiation curing, one of which is silicone. Silicone is a general term for organopolysiloxanes with a main chain of continuous siloxane bonds and organic groups such as methyl groups in the side chains. Silicones have excellent heat resistance, cold resistance, chemical resistance, electrical insulation, and mold releasability, and can be made into various forms such as oil, rubber, and resin. Radiation-curable silicones are used as raw materials for cured products such as silicone rubber, silicones for release paper, and silicones for hard coatings.

[0005] Organopolysiloxanes containing (meth)acryloyl groups as radiation-polymerizable groups are used in release coatings, hard coats, and surface tension adjusters. A cured product can be obtained by blending a photopolymerization initiator with this base material and irradiating it with radiation while purging with nitrogen in a chamber to efficiently react the radicals generated by radiation.

[0006] Several studies have been conducted on methods for producing such organopolysiloxanes containing (meth)acryloyl groups. In Patent Document 1, an organopolysiloxane containing (meth)acryloyl groups is produced by using an epoxy-modified organopolysiloxane as a raw material and reacting (meth)acrylic acid with an epoxy group. However, in this case, hydroxyl groups are generated as the epoxy ring opens, which increases the viscosity of the product, leaving a problem in terms of handling.

[0007] Patent Documents 2 and 3 propose a method of using a hydroxyl group-containing organopolysiloxane as a raw material and introducing (meth)acryloyl groups into the siloxane main chain by esterifying (meth)acrylic acid. The problem with this method is that the strong acid used in the esterification not only forms ester bonds but also cleaves siloxane bonds, making it extremely difficult to control the reaction conditions.

[0008] In Patent Documents 4 and 5, a silane material having a (meth)acryloyl group is oligomerized by hydrolysis and condensation, and then polymerized with other silicon oligomers having dimethyl units to synthesize the target organopolysiloxane. However, the synthesis of the raw material, a silane having a (meth)acryloyl group, is complicated and requires purification by distillation, but unless the conditions are precisely controlled, the (meth)acryloyl group is prone to polymerization.

[0009] Therefore, we decided to investigate a new production method: the synthesis of hydroxyl-containing organopolysiloxanes by transesterification using (meth)acrylic acid esters. Patent documents 6 and 7 disclose methods for producing (meth)acryloyl-containing organopolysiloxanes by transesterification using a Zr catalyst. While zirconium acetylacetonate (Zr(acac)4) is cited as a particularly versatile and effective catalyst, its powdery solid form makes handling difficult. Furthermore, because it is a solid, it can have poor compatibility with certain product structures, and disperse rather than dissolve in the target compound, resulting in turbidity and poor appearance. Additionally, Zr(acac)4 is expensive, and a process using less expensive, more versatile chemicals is desirable. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Special Publication No. 5-83570 [Patent Document 2] Special Publication No. 6-81826 [Patent Document 3] Patent No. 3780113 [Patent Document 4] Patent No. 2778403 [Patent Document 5] Patent No. 3176010 [Patent Document 6] Special Publication 2020-502306 [Patent Document 7] WO2019 / 082601 Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned above, conventional transesterification methods have sometimes had problems with the transparency of the resulting (meth)acryloyl group-containing organopolysiloxane, and the high cost of the catalyst used is also a bottleneck. Therefore, an object of the present invention is to provide a novel transesterification production method that reduces costs and produces a transparent (meth)acryloyl group-containing organopolysiloxane that has a good appearance. [Means for solving the problem]

[0012] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered a new production method in which a radically polymerizable organopolysiloxane containing a (meth)acryloyl group is obtained by transesterifying an organopolysiloxane containing a hydroxyl group-containing organic group with a (meth)acrylic acid ester in the presence of zirconium alkoxide and an organic compound having a specific structure as catalysts.

[0013] That is, the present invention is a method for producing a (meth)acryloyl group-containing organopolysiloxane, comprising: (A) a hydroxyl group-containing organopolysiloxane represented by the following average formula (1); [ka] (In the formula, R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, or a monovalent hydrocarbon group or (poly)oxyalkylenealkyl group having a terminal hydroxyl group (hereinafter collectively referred to as a hydroxyl group-containing group), and R 1 at least one of the groups is a hydroxyl group-containing group, a is a positive number of 2 or more, b is 0 or a positive number, c is 0 or a positive number, d is 0 or a positive number, and 2≦a+b+c+d≦1,000) (B) a (meth)acrylic acid ester represented by the following general formula (2), in an amount such that the molar ratio relative to 1 mole of hydroxyl groups of the component (A) is 1 to 10, [ka] (In the formula, R 2is a hydrogen atom or a methyl group, and R 3 is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 5 carbon atoms. The present invention provides the above-described production method, which comprises a step of reacting the components in the presence of the following components (C) and (D) to obtain the (meth)acryloyl group-containing organopolysiloxane: (C) a compound represented by the following general formula (3), which is liquid at 20°C, in an amount such that the molar ratio relative to 1 mole of hydroxyl groups in the component (A) is 0.001 to 0.1: Zr(OR 4 )4(3) (In the formula, R 4 is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, which may contain a carbonyl group. (D) a compound represented by the following general formula (4) or (5), which is liquid at 20°C, in an amount such that the molar ratio relative to 1 mole of hydroxyl groups in the component (A) is 0.002 to 0.8: [ka] (In the formula, R 5 and R 6 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms. [ka] (In the formula, R 7 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms). [Effects of the Invention]

[0014] The production method of the present invention efficiently produces the desired (meth)acryloyl group-containing organopolysiloxane through a transesterification reaction using inexpensive raw materials. Furthermore, because the catalyst used is liquid, it has excellent compatibility with the reaction substrates, and no solid remains after the reaction is completed, resulting in a product with good transparency. Furthermore, by not using a solid catalyst, the complicated process of loading a solid into the reaction apparatus is eliminated, simplifying the process. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below.

[0016] The present invention provides a method for producing a (meth)acryloyl group-containing organopolysiloxane. The (meth)acryloyl group-containing organopolysiloxane obtained by this method is particularly represented by the following average formula (5). [ka] (In the formula, R 8 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, the above-mentioned hydroxyl group-containing group, or a monovalent hydrocarbon group or (poly)oxyalkylene alkyl group having a (meth)acryloyloxy group at the terminal (hereinafter collectively referred to as a (meth)acryloyloxy group-containing group), and at least one R 8 is the (meth)acryloyloxy group-containing group, l is a positive number of 2 or more, m is 0 or a positive number, n is 0 or a positive number, o is 0 or a positive number, 2≦l+m+n+o≦1,000, and the number of silicon atoms to which hydroxyl group-containing groups are bonded is 0 to 30% of the total number of all silicon atoms).

[0017] The production method of the present invention will be described in more detail below. The production method of the present invention comprises: [ka] (In the formula, R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, or a monovalent hydrocarbon group or (poly)oxyalkylenealkyl group having a terminal hydroxyl group (hereinafter collectively referred to as a hydroxyl group-containing group), and R 1 at least one of the groups is a hydroxyl group-containing group, a is a positive number of 2 or more, b is 0 or a positive number, c is 0 or a positive number, d is 0 or a positive number, and 2≦a+b+c+d≦1,000) (B) a (meth)acrylic acid ester represented by the following general formula (2), in an amount such that the molar ratio relative to 1 mole of hydroxyl groups of the component (A) is 1 to 10, [ka] (In the formula, R 2 is a hydrogen atom or a methyl group, and R 3 is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 5 carbon atoms. The production method is characterized by including a step of reacting in the presence of the following component (C) and the following component (D) to obtain the (meth)acryloyl group-containing organopolysiloxane: (C) a compound represented by the following general formula (3), which is liquid at 20°C, in an amount such that the molar ratio relative to 1 mole of hydroxyl groups in the component (A) is 0.001 to 0.1: Zr(OR 4 )4(3) (In the formula, R 4 is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, which may contain a carbonyl group. (D) a compound represented by the following general formula (4) or (5), which is liquid at 20°C, in an amount such that the molar ratio relative to 1 mole of hydroxyl groups in the component (A) is 0.002 to 0.8: [ka] (In the formula, R 5 and R 6 are each independently an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 6 carbon atoms. [ka] (In the formula, R 7 is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 6 carbon atoms).

[0018] In the above formula (1), R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, or a hydroxyl group-containing group, and R 1At least one of the groups is a hydroxyl group-containing group. Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms include alkyl groups such as methyl, ethyl, propyl, and butyl, cycloalkyl groups such as cyclohexyl, and aryl groups such as phenyl and tolyl. These groups may have some or all of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms such as fluorine or chlorine, such as 3,3,3-trifluoropropyl, perfluorobutylethyl, or perfluorooctylethyl, or methoxypropyl or ethoxypropyl groups substituted with an alkoxy group. Examples of alkoxy groups include methoxy, ethoxy, isopropoxy, and butoxy. Methyl, ethyl, methoxy, ethoxy, and hydroxyl group-containing groups are preferred, provided that at least one R 1 is a hydroxyl-containing group.

[0019] Preferably, the number of silicon atoms bonded to hydroxyl-containing groups is 1 to 50%, more preferably 2 to 45%, and even more preferably 3 to 40% of the total number of silicon atoms. If the number of silicon atoms bonded to hydroxyl-containing groups is less than the above lower limit, curability by radiation may be insufficient. If it is more than the above upper limit, the substrate concentration of (meth)acrylic acid in the reaction system may increase during the reaction, which may cause viscosity increase or gelation due to polymerization of (meth)acryloyl groups.

[0020] The monovalent hydrocarbon group having a terminal hydroxyl group is preferably a monovalent hydrocarbon group having 2 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and having one terminal hydroxyl group. It is more preferably a monovalent hydrocarbon group having 2 to 10 carbon atoms, preferably 3 to 6 carbon atoms, and having one terminal hydroxyl group. The (poly)oxyalkylenealkyl group having a terminal hydroxyl group is a (poly)oxyalkylenealkyl group having one terminal hydroxyl group, preferably 4 to 25 carbon atoms, more preferably 5 to 16 carbon atoms. Examples of oxyalkylene groups include oxyethylene groups, oxyisopropylene groups, oxy-n-propylene groups, and oxybutylene groups. Oxyethylene groups and oxyisopropylene groups are preferred, and the hydroxyl group may contain two or more types of oxyalkylene groups. The hydroxyl group-containing group is, for example, represented by the following structure. In the formula below, the dotted line indicates the bond to the silicon atom of the organopolysiloxane. [ka]

[0021] R 2 is a hydrogen atom or a methyl group. e is an integer of 1 to 10, and f and g are each independently an integer of 1 to 5. Preferably, e is an integer of 1 to 7, and f and g are each independently an integer of 1 to 3. More preferably, e is an integer of 1 to 4, and f and g are each independently 1 or 2. In the above formula, the bonding order of the ethylene oxide and propylene oxide shown in parentheses is not limited, and they may be arranged randomly or form a block structure. In the formula, the dashed line indicates the bond to the silicon atom of the organopolysiloxane. As long as the hydroxyl group ratio of the entire composition satisfies the above range, the composition may contain a compound having both a hydroxyl group-containing organic group and a (meth)acryloyl group, as shown in the above diagram.

[0022] In the average formula (1), a is a positive number of 2 or greater, b is 0 or a positive number, c is 0 or a positive number, and d is 0 or a positive number, provided that 2≦a+b+c+d≦1,000. Preferably, the amount of hydroxyl-containing groups satisfies the above-mentioned range, and the organopolysiloxane has a viscosity at 25°C of 5 to 10,000 mPa·s, more preferably 10 to 5,000 mPa·s. The viscosity is measured using a BM-type rotational viscometer. The upper limits of a, b, c, and d may be any values that satisfy 2≦a+b+c+d≦1,000, and the organopolysiloxane has the above-mentioned viscosity. The upper limit of b is preferably 998 or less, more preferably 798 or less, and even more preferably 598 or less. The lower limit of b may be 0, but is preferably 1 or more, more preferably 5 or more, and even more preferably 8 or more. That is, preferably 1≦b≦998, more preferably 5≦b≦798, and even more preferably 8≦b≦598. c is preferably 0≦c≦5, more preferably 0≦c≦4, and even more preferably 0≦c≦3. d is preferably 0≦d≦4, more preferably 0≦d≦3, and even more preferably 0≦d≦2. The organopolysiloxane represented by the above average formula (1) more preferably has a linear structure.

[0023] Examples of organopolysiloxanes represented by average formula (1) include compounds represented by the following structures: In the formula, Me represents a methyl group, and Ph represents a phenyl group. [ka] (In the formula, h is an integer of 0 to 1,000, i is an integer of 0 to 800, j is an integer of 1 to 200, and k is an integer of 0 to 100. Preferably, h is a number that satisfies the above-mentioned 0≦b≦998, more preferably 1≦b≦998, more preferably 5≦b≦798, and even more preferably 8≦b≦598.)

[0024] [(B) Component] Component (B) is a (meth)acrylic acid ester represented by the following general formula (2), and is a reaction agent for introducing a (meth)acryloyl group into component (A). [ka]

[0025] In formula (2), R 2 is a hydrogen atom or a methyl group. 3 is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 5 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, butyl, and pentyl. From the viewpoints of industrial cost and ease of proceeding with the transesterification reaction, R 3 is preferably an alkyl group having 1 to 4 carbon atoms, i.e., a methyl group, an ethyl group, a propyl group, or a butyl group. 3 If the carbon number is more than 5, the boiling point of the alcohol produced during the transesterification reaction becomes high, making it difficult to remove it from the reaction system, and the transesterification reaction does not proceed easily, which is undesirable.

[0026] The amount of component (B) to be added is preferably 1 to 10 moles, more preferably 1.5 to 9 moles, and even more preferably 2 to 8 moles, of component (B) per mole of hydroxyl groups in organopolysiloxane (A). If the amount of component (B) is less than the lower limit, the rate of introduction of (meth)acryloyl groups via transesterification will decrease. If the amount is greater than the upper limit, the rate of introduction of (meth)acryloyl groups via transesterification will be high, but the amount of component (B) will be too high, resulting in a decrease in pot yield.

[0027] [(C) component] Component (C) is a compound represented by the following general formula (3) that is liquid at 20°C. Zr(OR 4 )4(3) (In the formula, R 4 is an unsubstituted or substituted, linear or branched monovalent hydrocarbon having 1 to 10 carbon atoms, which may contain a carbonyl group.

[0028] R4 is an unsubstituted or substituted, straight-chain or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, which may contain a carbonyl group within its structure. Examples include alkyl groups such as methyl, ethyl, propyl, butyl, isopropyl, and t-butyl; cycloalkyl groups such as cyclohexyl; phenyl; and acetyl. Examples of monovalent hydrocarbon groups containing a carbonyl group include acetyl and (meth)acryloyl groups. Alternatively, some or all of the hydrogen atoms bonded to these carbon atoms may be substituted with halogen atoms or other groups, such as trifluoromethyl and 3,3,3-trifluoropropyl. Component (C) is particularly preferred when the R 4 It is preferable that R is a zirconium alkoxide having an alkyl group having 1 to 6 carbon atoms. From the viewpoint of general availability, 4 is preferably a propyl group or a butyl group.

[0029] Component (C) is the main component of the catalyst for reacting components (A) and (B). The amount of component (C) is 0.001 to 0.1 moles, preferably 0.003 to 0.08 moles, and more preferably 0.005 to 0.05 moles per mole of hydroxyl groups in component (A). If the amount is less than the lower limit, the reaction may not proceed sufficiently. If the amount is more than the upper limit, removal of component (C) after the reaction may be difficult.

[0030] Component (C) is liquid at 20°C. Because component (C) is a liquid catalyst, it can be charged into a reaction vessel in the same way as liquid compounds such as components (A) and (B). If the catalyst is solid, measures must be taken when handling dust, which can make operations complicated. Furthermore, in the case of a solid catalyst, compatibility varies depending on the structure of the product, and the catalyst may disperse as a solid rather than dissolving in the product, causing the product to become cloudy.

[0031] [(D) component] Component (D) is a compound represented by the following general formula (4) or (5) and is liquid at 20°C. [ka] (In the formula, R 5 and R 6 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms. [ka] (In the formula, R 7 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms.

[0032] R 5 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, and butyl, cycloalkyl groups such as cyclohexyl, and phenyl groups. R is preferably a linear or branched monovalent hydrocarbon group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. From the viewpoint of general availability, R 5 is preferably a methyl group. Alternatively, some or all of the hydrogen atoms bonded to these carbon atoms may be substituted with halogen atoms or other groups, such as a trifluoromethyl group or a 3,3,3-trifluoropropyl group.

[0033] R 6 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, and butyl, cycloalkyl groups such as cyclohexyl, and phenyl groups. R is preferably a linear or branched monovalent hydrocarbon group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. From the viewpoint of general availability, R 6 are preferably a methyl group or an ethyl group. Alternatively, some or all of the hydrogen atoms bonded to these carbon atoms may be substituted with halogen atoms or other groups, such as a trifluoromethyl group or a 3,3,3-trifluoropropyl group.

[0034] Among the components (D), examples of the compound represented by the general formula (4) include methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, etc. Methyl acetoacetate and ethyl acetoacetate are preferred because of their general availability.

[0035] R 7 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, and butyl, cycloalkyl groups such as cyclohexyl, and phenyl groups. R is preferably a linear or branched monovalent hydrocarbon group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. From the viewpoint of general availability, R 7 are preferably a methyl group or an ethyl group. Alternatively, some or all of the hydrogen atoms bonded to these carbon atoms may be substituted with halogen atoms or other groups, such as a trifluoromethyl group or a 3,3,3-trifluoropropyl group.

[0036] Among the components (D), examples of the compounds represented by the general formula (5) include acetylacetone.

[0037] Component (D) functions in concert with the main catalyst component (C) for reacting components (A) and (B). It is believed that component (D) coordinates with component (C) to form a catalytic species that effectively functions in the transesterification of the present invention. The amount of component (D) is such that the molar ratio per mole of hydroxyl groups in component (A) is 0.002 to 0.8 moles, preferably 0.005 to 0.5 moles, and more preferably 0.01 to 0.4 moles. If the amount is less than the lower limit, the reaction may not proceed sufficiently. If the amount exceeds the upper limit, component (D) itself may function as a substrate for the transesterification reaction, potentially causing a side reaction.

[0038] [(E) component] Component (E) is a polymerization inhibitor, an additive that inhibits the polymerization of component (B), the (meth)acrylic acid ester, without reacting with component (A) during the reaction. There are no particular restrictions on the polymerization inhibitor as long as it has the effect of inhibiting radical polymerization, but examples of the polymerization inhibitor include alkylphenols such as those listed below.

[0039] p-Methoxyphenol, 2,6-di-t-butylhydroxytoluene, 4,4'-dioxydiphenol, 1,1'-bis(4-hydroxyphenyl)-cyclohexane, 3-methyl-4-isopropylphenol, 2,4,5-trihydroxybutyrophenone, 2,6-di-t-butylphenol, 2,5-di-t-amylhydroquinone, 2,5-di-t-butylhydroquinone, 4-hydroxymethyl-2,6-di-t-butylphenol, 2,6-di-t-butyl-dimethylamino-p-cresol, 4,4-bis(2,6-dibutylphenol) ol), 2,2'-methylene-bis(4-ethyl-6-t-butylphenol), 2,2'-methylene(2,6-di-t-butylphenol), 4,4'-methylene(2,6-di-t-butylphenol), 4,4'-butylidene(3-methyl-6-t-butylphenol), 4,4'-thio-bis(6-t-butyl-3-methylphenol), bis(3-methyl-4-hydroxy-5-t-butylbenzyl) sulfide, 4,4'-thio-bis(6-t-butyl-o-cresol), 2,2'-thio-bis(4-methyl-6-t-butylphenol).

[0040] Amine-based polymerization inhibitors can also be used, including alkylated diphenylamines, N,N'-diphenyl-p-phenylenediamine, phenothiazine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0041] The amount of polymerization inhibitor is 0.01 to 1 part by mass, preferably 0.02 to 0.5 parts by mass, and more preferably 0.03 to 0.3 parts by mass, per 100 parts by mass of component (A). If the amount is greater than the upper limit, the curability of the resulting radiation-curable organopolysiloxane composition containing the radical-polymerizable organopolysiloxane may decrease. If the amount is less than the lower limit, there is a risk that the (meth)acrylic acid will polymerize during production, resulting in increased viscosity or gelation.

[0042] [solvent] The transesterification reaction of the present invention can be carried out without a solvent or in an organic solvent. Examples of organic solvents include aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as hexane, heptane, octane, isooctane, cyclohexane, methylcyclohexane, and isoparaffin, hydrocarbon solvents such as industrial gasoline, petroleum benzine, and solvent naphtha, ether solvents such as diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, 1,2-dimethoxyethane, and 1,4-dioxane, and mixed solvents thereof. These solvents can be used alone or in appropriate combinations of two or more.

[0043] [Transesterification] In this invention, the hydroxyl groups contained in component (A) and the alkyl ester moieties of component (B) undergo transesterification using catalysts (C) and (D) to obtain the target organopolysiloxane. The reaction is outlined below. Note that Siloxane-OH in the formula is a hydroxyl-containing organopolysiloxane represented by formula (1) above, and examples thereof include the compounds exemplified for component (A) above. TIFF0007723760000015.tif23170

[0044] The reaction temperature can be 70 to 150°C, preferably 75 to 145°C, and more preferably 80 to 140°C. Temperatures below 70°C may prevent the by-product alcohol from being sufficiently released from the reaction system, resulting in insufficient reaction progress. Temperatures above 150°C may result in increased viscosity and gelation due to polymerization of the (meth)acrylic acid ester (B). The reaction time may be within the range of 1 to 72 hours, but is not limited thereto. The reaction atmosphere may be a nitrogen atmosphere or air, or a mixed gas such as nitrogen containing a small amount of oxygen may be used. The amount of oxygen in this case is 0.1 to 20% by volume, preferably 0.5 to 18%, and more preferably 1 to 15%.

[0045] After the reaction is complete, the remaining component (B) can be distilled off under reduced pressure to obtain the product. The distillation temperature may be 20°C to 120°C and the reduced pressure may be 1 to 200 mmHg, but this is not a limitation. As described above, the (meth)acryloyl group-containing organopolysiloxane obtained in the present invention is represented by the following average formula (5). [ka]

[0046] R in the formula 8 is R in the above average formula (1). 1 or a monovalent hydrocarbon group or (poly)oxyalkylene group having a (meth)acryloyl group at the terminal (hereinafter collectively referred to as a (meth)acryloyloxy group-containing group). 8 At least one of them is a (meth)acryloyloxy group-containing group. The number of silicon atoms to which the (meth)acryloyloxy group-containing group is bonded is preferably 1 to 50%, more preferably 2 to 45%, and even more preferably 3 to 40%, of the total number of all silicon atoms.

[0047] The (meth)acryloyloxy group-containing group is a group in which the terminal hydroxyl group of the above-mentioned hydroxyl group-containing group has been substituted with a (meth)acryloyloxy group. Therefore, unlike a group in which a (meth)acryloyloxy group has been introduced by ring-opening of an epoxy group, it does not have a hydroxyl group. Preferably, it is a monovalent hydrocarbon group having 2 to 10 carbon atoms, preferably 3 to 6 carbon atoms, and having one (meth)acryloyloxy group at its terminal, or a (poly)oxyalkylenealkyl group having 4 to 25 carbon atoms, preferably 5 to 16 carbon atoms, and having one (meth)acryloyloxy group at its terminal. Examples of the oxyalkylene group are as described above, with oxyethylene and oxyisopropylene groups being preferred, and the group may contain two or more types of oxyalkylene groups. For example, it may be represented by the following structure. In the formula below, the dotted line indicates the bond to the silicon atom of the polysiloxane. [ka]

[0048] R 2 is a hydrogen atom or a methyl group. e is an integer of 1 to 10, and f and g are each independently an integer of 1 to 5. Preferably, e is an integer of 1 to 7, and f and g are each independently an integer of 1 to 3. More preferably, e is an integer of 1 to 4, and f and g are each independently 1 or 2. In the above formula, the bonding order of the ethylene oxide and propylene oxide shown in parentheses is not limited, and they may be arranged randomly or may form a block structure. In addition, in the formula, the dashed line represents a bond to the silicon atom of the organopolysiloxane.

[0049] In the average formula (5), l is a positive number of 2 or greater, m is 0 or a positive number, n is 0 or a positive number, and o is 0 or a positive number, with 2≦l+m+n+o≦1,000. Preferably, the amount of (meth)acryloyloxy group-containing organic groups satisfies the above range, and the organopolysiloxane has a viscosity at 25°C of 5 to 10,000 mPa·s, more preferably 10 to 5,000 mPa·s. The (meth)acryloyl group-containing organopolysiloxane obtained by the above production method of the present invention can have a low viscosity, preferably 5 to 3,000 mPa·s, more preferably 5 to 2,000 mPa·s, even more preferably 8 to 1,500 mPa·s, even 10 to 1,000 mPa·s, and particularly preferably 15 to 700 mPa·s. The viscosity is a value measured by a BM type rotational viscometer. The upper limits of l, m, n, and o may be any values that satisfy the relationship 2≦l+m+n+o≦1,000 and allow the organopolysiloxane to have the above-described viscosity. The upper limit of m is preferably 998 or less, more preferably 798 or less, and even more preferably 598 or less. The lower limit of m may be 0, but preferably m is 1 or more, more preferably 5 or more, and even more preferably 8 or more. That is, preferably 1≦m≦998, more preferably 5≦m≦798, and even more preferably 8≦m≦598. n is preferably 0≦n≦5, more preferably 0≦n≦4, and even more preferably 0≦n≦3. o is preferably 0≦o≦4, more preferably 0≦o≦3, and even more preferably 0≦o≦2. The organopolysiloxane represented by the average formula (5) above more preferably has a linear structure. [Example]

[0050] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following, the physical properties in the tables were measured by the following test methods. In the examples, "parts" means "parts by mass."

[0051] [(Meth)acryloyl group introduction rate] The introduction rate of (meth)acryloyl groups in the transesterification reaction in the examples and comparative examples was calculated as follows: The introduction rate of (meth)acryloyl groups in the esterification reaction of the present invention was calculated as follows: 1 Using H-NMR, the methylene proton (δ = 0.42) bonded to the Si atom of the hydroxyl-containing organic group in the starting hydroxyl-containing organopolysiloxane was used as the reference peak, since it remained unchanged before and after the reaction. For example, in the case of acryloyl groups, the peak integral of the reference methylene proton was set to 1.00, and if the introduction rate of acryloyl groups through the esterification reaction is 100%, the peak integral of each of the three protons in the acryloyl group would be 0.50. From this, the introduction rate of acryloyl groups is determined by the following formula: Acryloyl group introduction rate = [(average of integral values of three proton peaks of acryloyl group) / 0.50] x 100 (%)

[0052] [Example 1] A separable flask equipped with a stirrer, a thermometer, and a Dean-Stark apparatus was charged with 72.91 g of organopolysiloxane represented by the following average formula (A-1), 47.09 g of (B-1) ethyl acrylate (an amount equivalent to 3 moles per mole of hydroxyl groups in the organopolysiloxane (A-1)), 0.18 g of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) monoacrylate as a polymerization inhibitor, and (C-1) zirconium tetrabutyl acrylate. 0.902 g of an 80% butanol solution of methyl acrylate (liquid at 20°C) (amount equivalent to 0.012 moles per mole of hydroxyl groups in the organopolysiloxane (A-1)) and 0.979 g of (D-1) ethyl acetoacetate (liquid at 20°C) (amount equivalent to 0.048 moles per mole of hydroxyl groups in the organopolysiloxane (A-1)) were charged, and the reaction was carried out with heating and stirring for 24 hours while the by-product ethanol was distilled off using a nitrogen flow at a temperature of 85°C. The reaction solution was then distilled at 85°C for 2 hours under reduced pressure at 20 mmHg to remove unreacted components, yielding an organopolysiloxane represented by the following average formula (X-1). The target product was yellow and transparent, and the acryloyl group introduction rate was 98%. [ka] [ka]

[0053] [Example 2] Into a separable flask equipped with a stirrer, a thermometer, and a Dean-Stark apparatus, 72.91 g of organopolysiloxane represented by the following average formula (A-2), 47.09 g of (B-1) ethyl acrylate (an amount equivalent to 3 moles per mole of hydroxyl groups in the organopolysiloxane (A-1)), 0.18 g of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) monoacrylate as a polymerization inhibitor, and (C-1) zirconium were added. 1.503 g of an 80% butanol solution of tetrabutoxide (liquid at 20°C) (0.02 moles per mole of hydroxyl groups in the organopolysiloxane (A-2)) and 1.632 g of (D-1) ethyl acetoacetate (liquid at 20°C) (0.08 moles per mole of hydroxyl groups in the organopolysiloxane (A-2)) were added, and the reaction was carried out with heating and stirring for 24 hours while distilling off the by-product ethanol at a temperature of 85°C. The reaction solution was then distilled at 85°C for 2 hours under reduced pressure at 20 mmHg to remove unreacted components, yielding a transparent yellow product. The product was an organopolysiloxane represented by the average formula (X-2) below. The acryloyl group introduction rate was 98%. [ka] [ka]

[0054] [Example 3] Example 2 was repeated, except that 1.456 g (0.08 moles per mole of hydroxyl groups in the organopolysiloxane (A-2)) of (D-2) methyl acetoacetate (liquid at 20°C) was used instead of (D-1) ethyl acetoacetate, to obtain a yellow, transparent target product. The acryloyl group introduction rate was 96%.

[0055] [Example 4] Example 2 was repeated, except that (C-1) the 80% butanol solution of zirconium tetrabutoxide was replaced with 3.668 g of (C-2) a 70% propanol solution of zirconium tetrapropoxide (liquid at 20°C) (amount equivalent to 0.05 moles per mole of hydroxyl groups in the organopolysiloxane (A-2)), and the amount of (D-1) ethyl acetoacetate was changed to 4.080 g (amount equivalent to 0.2 moles per mole of hydroxyl groups in the organopolysiloxane (A-2)), to obtain a yellow, transparent target product. The acryloyl group introduction rate was 98%.

[0056] [Example 5] Example 2 was repeated, except that 1.256 g of (D-3) acetylacetone (amount equivalent to 0.08 moles per mole of hydroxyl groups in the organopolysiloxane (A-2)) was used instead of (D-1) ethyl acetoacetate, to obtain a yellow, transparent target product. The acryloyl group introduction rate was 98%.

[0057] [Comparative Example 1] Example 1 was repeated except that ethyl acetoacetate (D-1) was not used, to obtain a yellow, transparent target product. The acryloyl group introduction rate was 19%.

[0058] Comparative Example 2 Example 1 was repeated except that the 80% butanol solution of (C-1) zirconium tetrabutoxide was not used, to obtain a yellow, transparent target product. The acryloyl group introduction rate was 5%.

[0059] Comparative Example 3 In Example 1, 0.902 g of an 80% butanol solution of (C-1) zirconium tetrabutoxide (0.012 moles per mole of hydroxyl groups in the organopolysiloxane (A-1)) was used, and (D-1) zirconium acetylacetonate (Zr(acac) 4、Example 1 was repeated, except that 0.764 g (amount equivalent to 0.01 mole per mole of hydroxyl groups in the organopolysiloxane (A-1)) of Zr(acac) (melting point 191°C) was used. The resulting product was a slightly cloudy yellow solution, with residual solids derived from Zr(acac) remaining. The acryloyl group introduction rate was 98%.

[0060] Comparative Example 4 Example 2 was repeated, except that 0.902 g of an 80% butanol solution of (C-1) zirconium tetrabutoxide (amount equivalent to 0.012 equivalents relative to the hydroxyl groups in the organopolysiloxane (A-1)) was used, and 0.764 g of (D-1) zirconium acetylacetonate (Zr(acac)4, melting point 191°C) (amount equivalent to 0.01 mole relative to 1 mole of hydroxyl groups in the organopolysiloxane (A-1)) was used instead of ethyl acetoacetate, to obtain a yellow, transparent target product. The acryloyl group introduction rate was 99%.

[0061] The catalyst (Zr(acac)4) used in Comparative Examples 3 and 4 is a powder, which can make operations complicated. For example, the powder must be directly charged into an open-close inlet, rather than being charged through a pressure-fed supply line, which can be a hassle.

[0062] [Table 1] [Industrial Applicability]

[0063] The production method of the present invention uses inexpensive raw materials and is simple to operate, making it possible to efficiently produce the desired organopolysiloxane. Furthermore, the use of a liquid catalyst can alleviate the problem of poor appearance due to the insoluble nature of solid catalysts. The resulting (meth)acryloyl-modified organopolysiloxane can be used in radiation-curable coating agents, additives, resins, and the like.

Claims

1. A method for producing a (meth)acryloyl group-containing organopolysiloxane, comprising the steps of: (A) a hydroxyl group-containing organopolysiloxane represented by the following average formula (1): 【Chemical 1】 (In the formula, R １ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, or a monovalent hydrocarbon group or (poly)oxyalkylenealkyl group having a terminal hydroxyl group (hereinafter collectively referred to as a hydroxyl group-containing group), and R １ at least one of the above is a hydroxyl group-containing group, and the hydroxyl-containing organopolysiloxane has hydroxyl groups in a number such that the number of silicon atoms to which the hydroxyl-containing groups are bonded accounts for 1 to 50% of the total number of silicon atoms, a is a positive number of 2 or more, b is 0 or a positive number, c is 0 or a positive number, d is 0 or a positive number, and 2≦a+b+c+d≦1,000. (B) a (meth)acrylic acid ester represented by the following general formula (2) in an amount such that the molar ratio relative to 1 mole of hydroxyl groups of the component (A) is 1 to 10, 【Chemistry 2】 (In the formula, R ２ is a hydrogen atom or a methyl group, and R ３ is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 5 carbon atoms. the production method, characterized by including a step of reacting the components in the presence of the following component (C) and the following component (D) to obtain the (meth)acryloyl group-containing organopolysiloxane: (C) a compound represented by the following general formula (3) which is liquid at 20°C, in an amount such that the molar ratio relative to 1 mole of hydroxyl groups in the component (A) is 0.001 to 0.1 Zr(OR ４ ) ４ (3) (In the formula, R ４ is an unsubstituted or substituted, linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, which may contain a carbonyl group. (D) A compound represented by the following general formula (4) or (5), which is liquid at 20°C, in an amount such that the molar ratio relative to 1 mole of hydroxyl groups in the component (A) is 0.002 to 0.8: 【Chemistry 3】 (In the formula, R ５ and R ６ are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms. 【Chemistry 4】 (In the formula, R ７ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms).

2. 2. The method according to claim 1, wherein the number of silicon atoms to which the hydroxyl-containing groups are bonded in component (A) is 3 to 40% of the total number of silicon atoms.

3. The component (C) is the R ４ 3. The method according to claim 1, wherein the zirconium alkoxide has an alkyl group having 1 to 6 carbon atoms.

4. 3. The method according to claim 1, further comprising blending, in the step, 0.01 to 1 part by mass of a polymerization inhibitor (E) relative to 100 parts by mass of the component (A).

5. 3. The production method according to claim 1 or 2, wherein in the step, components (A) to (D), and optionally component (E), are mixed and stirred in a reaction vessel while heating the mixture in the reaction vessel to 70 to 150°C, and component (A) and component (B) are reacted while removing by-produced alcohol from the reaction vessel.

6. The method of claim 1, wherein the (meth)acryloyl group-containing organopolysiloxane is represented by the following average formula (5): 【Chemistry 5】 (In the formula, R ８ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, the above-mentioned hydroxyl group-containing group, or a monovalent hydrocarbon group or (poly)oxyalkylene alkyl group having a (meth)acryloyloxy group at the terminal (hereinafter collectively referred to as a (meth)acryloyloxy group-containing group), and at least one R ８ is the (meth)acryloyloxy group-containing group, l is a positive number of 2 or more, m is 0 or a positive number, n is 0 or a positive number, o is 0 or a positive number, 2≦l+m+n+o≦1,000, and the number of silicon atoms to which hydroxyl group-containing groups are bonded is 0 to 30% of the total number of all silicon atoms).

7. 3. The method according to claim 1, wherein the hydroxyl-containing group is at least one selected from the following: (In the formula, R ２ is a hydrogen atom or a methyl group, e is an integer of 1 to 10, f and g are each independently an integer of 1 to 5, and in the above formula, the bonding order of the ethylene oxide and propylene oxide shown in the parentheses is not limited, and they may be arranged randomly or form a block structure, and in the formula, the dashed line represents a bond to the silicon atom of the organopolysiloxane.

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