Method for purifying (meth)acrylic functional organosilicon compounds, and (meth)acrylic functional organosilicon compounds

Abstract

To provide a (meth)acrylic-functional organosilicon compound purification method, including a step for subjecting a crude product containing a (meth)acrylic-functional organosilicon compound to thin film distillation in the presence of N-nitroso-N-phenylhydroxylamine aluminum, and the method being capable of reducing the amount of N-nitroso-N-phenylhydroxylamine aluminum mixed in a fraction during the thin film distillation.SOLUTION: Provided is a (meth)acrylic-functional organosilicon compound purification method, the method being characterized by comprising: a step 1 of subjecting a crude product containing a (meth)acrylic-functional organosilicon compound to thin film distillation in the presence of N-nitroso-N-phenylhydroxylamine aluminum; a step 2 of mixing a fraction obtained by the thin film distillation and containing the (meth)acrylic-functional organosilicon compound with an adsorbent to produce a mixture; and a step 3 of filtrating out the adsorbent from the mixture to produce the (meth)acrylic-functional organosilicon compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for purifying a (meth)acrylic-functional organosilicon compound, and to a (meth)acrylic-functional organosilicon compound. [Background technology]

[0002] (Meth)acrylic compounds self-polymerize due to heat during production, causing gelation in reactors and distillation pots, or gelation and clogging of piping in distillation equipment, causing significant damage to the production process.

[0003] Known techniques for preventing self-polymerization include the use of phenolic polymerization inhibitors such as p-hydroquinone and 4-methoxyphenol, quinone polymerization inhibitors such as p-benzoquinone and 2,5-di-tert-butylbenzoquinone, and hindered phenolic polymerization inhibitors with sterically hindering substituents, such as 2,6-di-tert-butyl-4-methylphenol and 2,2'-methylene-bis(6-tert-butyl-4-ethylphenol).

[0004] However, none of these methods can adequately prevent polymerization reactions in the still, which is kept at high temperatures for a long time during the distillation process, and therefore are often almost unsuitable for industrial-scale production.Furthermore, since 2,6-di-tert-butyl-4-methylphenol is gradually distilled out together with the target compound during the distillation process, although these methods are relatively effective in preventing polymerization reactions in the vapor state, they inevitably cannot prevent polymerization reactions in the still, which is kept at high temperatures in the latter half of the distillation process.

[0005] To address this issue, methods such as adding 2,6-di-tert-butyl-4-methylphenol during distillation (Patent Document 1) and adding N-nitroso-N-phenylhydroxylamine aluminum (Patent Document 2) are known. Also known is a method of adding N-nitroso-N-phenylhydroxylamine aluminum during thin-film distillation (Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-25907 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-327617 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-335715 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the above-mentioned thin-film distillation, N-nitroso-N-phenylhydroxylamine aluminum can be mixed into the distillate. If the purified (meth)acrylic-functional organosilicon compound contains aluminum, it can reduce the reactivity of the (meth)acrylic-functional organosilicon compound during polymerization, or it can remain in the product after the polymerization reaction, causing problems. Therefore, a method for reducing or removing N-nitroso-N-phenylhydroxylamine aluminum from the distillate after thin-film distillation was needed.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a method for purifying a (meth)acrylic-functional organosilicon compound, which comprises a step of thin-film distilling a crude product containing a (meth)acrylic-functional organosilicon compound in the presence of N-nitroso-N-phenylhydroxylamine aluminum, and which reduces the amount of N-nitroso-N-phenylhydroxylamine aluminum mixed into the fraction during thin-film distillation. [Means for solving the problem]

[0009] That is, the present invention provides a method for purifying a (meth)acrylic-functional organosilicon compound, comprising the steps of: The method includes the steps of: (1) thin-film distilling the crude product containing the (meth)acrylic functional organosilicon compound in the presence of N-nitroso-N-phenylhydroxylamine aluminum; Step 2: mixing the fraction containing the (meth)acrylic-functional organosilicon compound obtained by the thin-film distillation with an adsorbent; and The purification method is characterized by including a step 3 of obtaining a (meth)acrylic-functional organosilicon compound by filtering the adsorbent from the mixture.

[0010] Furthermore, the present invention provides a purification method having at least one constituent requirement selected from the following [1] to [8]. [1] The above purification method, wherein the amount of the adsorbent is 0.1 to 20 parts by mass per 100 parts by mass of the (meth)acrylic-functional organosilicon compound subjected to step 2. [2] The above purification method, wherein the adsorbent is hydrotalcite or activated carbon. [3] The above purification method, wherein the amount of N-nitroso-N-phenylhydroxylamine aluminum is 0.001 to 0.5 parts by mass per 100 parts by mass of the (meth)acrylic-functional organosilicon compound subjected to step 1. [4] The above purification method, wherein the amount of aluminum in the (meth)acrylic-functional organosilicon compound obtained in the above step 3 is less than 1 ppm. [5] The above purification method, wherein the (meth)acrylic-functional organosilicon compound is a linear or branched organopolysiloxane having at least one (meth)acrylic group-containing organic group in each molecule. [6] The above purification method, wherein the (meth)acrylic functional organosilicon compound has a weight average molecular weight of 400 to 5,000. [7] The above purification method, wherein the (meth)acrylic functional organosilicon compound is represented by the following formula (1): [ka] In the formula, R 1 are each independently a monovalent hydrocarbon group having 1 to 8 carbon atoms, n is a number satisfying 0≦n≦50, and R2 are each independently 1 or a group represented by the following formula (2), wherein R 2 At least one of the groups is a group represented by the following formula (2): [ka] (In the formula, R 3 is a divalent hydrocarbon group having 1 to 8 carbon atoms, and R 4 is a hydrogen atom or a methyl group, and x, y, and z are numbers from 0 to 30 that satisfy the relationship 0≦(x+y+z)≦30). [8] The above purification method, wherein the (meth)acrylic functional organosilicon compound is represented by the above formula (2), where x, y, and z are numbers from 0 to 30 and satisfy the relationship 1≦(x+y+z)≦30.

[0011] The present invention further provides a (meth)acrylic-functional organosilicon compound that is a purified product obtained by thin-film distillation in the presence of N-nitroso-N-phenylhydroxylamine aluminum, wherein the aluminum content derived from the N-nitroso-N-phenylhydroxylamine aluminum is less than 1 ppm. The (meth)acrylic functional organosilicon compound preferably has at least one constituent requirement selected from the following [9] to

[12] . [9] The (meth)acrylic-functional organosilicon compound, which is a linear or branched organopolysiloxane having at least one (meth)acrylic group-containing organic group in each molecule.

[10] The (meth)acrylic functional organosilicon compound, which has a weight average molecular weight of 400 to 5,000.

[11] The (meth)acrylic functional organosilicon compound represented by the following formula (1): [ka] In the formula, R 1 are each independently a monovalent hydrocarbon group having 1 to 8 carbon atoms, n is a number satisfying 0≦n≦50, and R2 are each independently 1 or a group represented by the following formula (2), wherein R 2 At least one of the groups is a group represented by the following formula (2): [ka] (In the formula, R 3 is a divalent hydrocarbon group having 1 to 8 carbon atoms, and R 4 is a hydrogen atom or a methyl group, and x, y, and z are numbers from 0 to 30 that satisfy the relationship 0≦(x+y+z)≦30).

[12] The (meth)acrylic-functional organosilicon compound, wherein in the formula (2), x, y, and z are numbers from 0 to 30 and satisfy the relationship 1≦(x+y+z)≦30. [Effects of the Invention]

[0012] The method of the present invention can suppress gelation of the product when a (meth)acrylic-functional organosilicon compound is subjected to thin-film distillation, and can also provide a (meth)acrylic-functional organosilicon compound with a reduced amount of N-nitroso-N-phenylhydroxylamine aluminum mixed into the fraction after thin-film distillation. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the present invention, the method for purifying a (meth)acrylic functional organosilicon compound comprises: 1) Step 1: thin-film distillation of a crude product containing a (meth)acrylic-functional organosilicon compound in the presence of N-nitroso-N-phenylhydroxylamine aluminum; 2) step 2 of mixing the fraction containing the (meth)acrylic-functional organosilicon compound obtained by the thin-film distillation with an adsorbent; and 3) Step 3: Obtaining a (meth)acrylic-functional organosilicon compound by filtering the adsorbent from the mixture.

[0014] The amount of N-nitroso-N-phenylhydroxylamine aluminum added in the thin-film distillation step is in the range of 0.001 to 0.5 parts by mass, preferably 0.001 to 0.1 parts by mass, and more preferably 0.001 to 0.02 parts by mass, per 100 parts by mass of the (meth)acrylic-functional organosilicon compound contained in the crude product subjected to thin-film distillation.

[0015] The structure of the (meth)acrylic-functional organosilicon compound purified by the method of the present invention is not particularly limited, and may be any conventionally known (meth)acrylic-functional organosilicon compound. For example, a linear or branched organopolysiloxane having at least one (meth)acrylic-group-containing organic group per molecule is used, more preferably a linear or branched organopolysiloxane having one (meth)acrylic-group-containing organic group at one end or one at each end. The (meth)acrylic-group-containing organic group is an organic group having a (meth)acrylic group at its end. Examples of such organic groups include divalent hydrocarbon groups having 2 to 40 carbon atoms, which may contain a hydroxyl group or an ether bond. Preferred examples include alkylene groups having 1 to 10 carbon atoms and oxyalkylene groups having 2 to 40 carbon atoms.

[0016] The weight-average molecular weight of the (meth)acrylic functional organosilicon compound is preferably in the range of 400 to 5,000, more preferably 500 to 2,000. Note that this molecular weight refers to the weight-average molecular weight measured by GPC (gel permeation chromatography) using polystyrene as the standard substance.

[0017] For example, a (meth)acrylic functional organosilicon compound represented by the following formula (1) can be mentioned. [ka] In formula (1), R 1 are each independently a monovalent hydrocarbon group having 1 to 8 carbon atoms, n is a number satisfying 0≦n≦50, and R 2 are independently of each other and are the above R 1 or a group represented by the following formula (2),2 At least one of the groups is a group represented by the following formula (2). [ka] In formula (2), R 3 is a divalent hydrocarbon group having 1 to 8 carbon atoms, and R 4 is a hydrogen atom or a methyl group, and x, y, and z are numbers from 0 to 30 that satisfy the relationship 0≦(x+y+z)≦30.

[0018] Above R 1 Examples of the alkyl group include alkyl groups such as methyl, ethyl, propyl, and butyl, cycloalkyl groups such as cyclopentyl and cyclohexyl, aryl groups such as phenyl and tolyl, and aralkyl groups such as benzyl and phenethyl. An alkyl group having 1 to 4 carbon atoms or a phenyl group is preferred, and a methyl group is more preferred.

[0019] Above R 2 As for the above R 1 or a group selected from the group represented by the above formula (2), provided that the above R 2 At least one of these, preferably either one of these, is a group represented by the above formula (2).

[0020] Above R 3 are each independently a divalent hydrocarbon group having 1 to 8 carbon atoms. 3 is not particularly limited, and examples thereof include -(CH2)-, -(CH2)2-, -(CH2)3-, -(CH2)4-, -CH2CH(CH3)CH2-, and -(CH2)8-, and preferably -(CH2)2-, -(CH2)3-, and -(CH2)4-.

[0021] Above R 4is a hydrogen atom or a methyl group, preferably a methyl group. x, y, and z are each an integer of 0 to 30, preferably an integer of 1 to 20, more preferably an integer of 1 to 10. They are also integers that satisfy 0≦(x+y+z)≦30, preferably an integer that satisfies 1≦(x+y+z)≦30. They are preferably integers that satisfy 0 or 1≦(x+y+z)≦20, more preferably an integer that satisfies 1≦(x+y+z)≦10.

[0022] In the present invention, the method for synthesizing the (meth)acrylic-functional organosilicon compound is not particularly limited, and may be any conventionally known method. For example, the (meth)acrylic-functional organosilicon compound can be obtained by a hydrosilylation reaction between a hydrogenpolysiloxane and 2-allyloxyethyl methacrylate.

[0023] [Thin film distillation process] The method of the present invention, in the purification step of a crude product containing a (meth)acrylic-functional organosilicon compound synthesized by the above-mentioned method, includes a step of adding N-nitroso-N-phenylhydroxylamine aluminum to the crude product and subjecting it to thin-film distillation. By performing thin-film distillation in the presence of N-nitroso-N-phenylhydroxylamine aluminum, gelation and thickening of the product during thin-film distillation are suppressed.

[0024] In the method of the present invention, the thin-film distillation temperature of the (meth)acrylic-functional organosilicon compound containing N-nitroso-N-phenylhydroxylamine aluminum is not particularly limited, but is preferably in the range of 80 to 250°C, more preferably 100 to 200°C, and even more preferably 130 to 180°C. This thin-film distillation is usually carried out under reduced pressure. More specifically, the pressure is preferably in the range of 1 to 100 Pa, more preferably 10 to 50 Pa. This thin-film distillation may be carried out either under aerobic conditions without entrainment of gas, or under aerobic conditions with entrainment of gas, such as nitrogen or air. The condenser temperature (cooling temperature) is 0 to 50°C, preferably 10 to 30°C. Examples of thin-film distillation equipment include the MS-300 rotary thin-film molecular distillation apparatus manufactured by Shibata Scientific Instruments Co., Ltd.

[0025] The amount of N-nitroso-N-phenylhydroxylamine aluminum to be mixed during thin-film distillation is in the range of 0.001 to 0.5 parts by mass, preferably 0.002 to 0.1 parts by mass, and more preferably 0.0025 to 0.02 parts by mass, per 100 parts by mass of the (meth)acrylic-functional organosilicon compound contained in the crude product to be subjected to thin-film distillation.

[0026] [Adsorption treatment process] The purification method of the present invention comprises the steps of mixing the fraction containing the (meth)acrylic-functional organosilicon compound obtained by the thin-film distillation with an adsorbent, and filtering the adsorbent from the mixture.

[0027] Examples of adsorbents include hydrotalcite, activated carbon, and silica gel. Hydrotalcite or activated carbon is preferred. Examples of hydrotalcite include Kyoward 500, Kyoward 1000, Kyoward 2000, and DHT-4A (manufactured by Kyowa Chemical Industry Co., Ltd.). The amount of adsorbent added is 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the (meth)acrylic-functional organosilicon compound contained in the crude product.

[0028] The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound after purification should be as small as possible. Aluminum may inhibit the reactivity of the (meth)acrylic-functional organosilicon compound. In the present invention, the amount of aluminum in the (meth)acrylic-functional organosilicon compound after adsorption treatment is preferably less than 1 ppm relative to the mass of the (meth)acrylic-functional organosilicon compound, and preferably as low as possible below 1 ppm, or even 0 ppm. Therefore, the present invention further provides a (meth)acrylic-functional organosilicon compound that is a purified product of thin-film distillation in the presence of N-nitroso-N-phenylhydroxylamine aluminum, wherein the aluminum content derived from the N-nitroso-N-phenylhydroxylamine aluminum is less than 1 ppm. The preferred (meth)acrylic-functional organosilicon compound is as described above.

[0029] In the present invention, the amount of aluminum derived from N-nitroso-N-phenylhydroxylamine aluminum in the (meth)acrylic-functional organosilicon compound refers to a value measured by ICP-MS. [Example]

[0030] 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 examples, "%" in the composition indicates % by mass unless otherwise specified.

[0031] [Example 1] After mixing 170 g of 2-allyloxyethyl methacrylate, 170 g of toluene, and 0.8 g of a toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (platinum concentration 0.5%), 430 g of hydrogenpolysiloxane of the following structural formula was added dropwise and aged for 4 hours at 80°C. After aging was complete, the mixture was concentrated under reduced pressure and filtered, yielding a pale yellow, transparent liquid. [ka] The resulting product was a crude product of a (meth)acrylic functional organosilicon compound (molecular weight: 582) represented by the following formula. [ka] 100 g of the crude product of the (meth)acrylic functional organosilicon compound was mixed and dissolved with 0.001 g of N-nitroso-N-phenylhydroxylamine aluminum (product name: Q-1301, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polymerization inhibitor, and thin-film distillation was carried out at a temperature of 150° C., a pressure of 30 Pa, and a condenser temperature of 20° C. The amount of aluminum in the obtained fraction was less than 1 ppm. To 85 g of the distillation fraction containing the (meth)acrylic-functional organosilicon compound obtained above, 1 mass% of hydrotalcite (trade name: Kyoward 500, manufactured by Kyowa Chemical Industry Co., Ltd.) was added as an adsorbent, and the mixture was mixed at room temperature (25°C) for 2 hours. The adsorbent was then removed by filtration, yielding a purified (meth)acrylic-functional organosilicon compound. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0032] [Example 2] The method of Example 1 was repeated except that the amount of polymerization inhibitor was changed from 0.001 g to 0.0025 g to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0033] [Example 3] The method of Example 1 was repeated except that the amount of polymerization inhibitor was changed from 0.001 g to 0.005 g to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0034] [Example 4] The method of Example 1 was repeated except that the amount of polymerization inhibitor was changed from 0.001 g to 0.01 g to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0035] [Example 5] The method of Example 1 was repeated except that the amount of polymerization inhibitor was changed from 0.001 g to 0.02 g to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of residual aluminum in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0036] [Example 6] The method of Example 1 was repeated except that the amount of polymerization inhibitor was changed from 0.001 g to 0.05 g to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0037] [ Reference Example 7] The method of Example 1 was repeated, except that the amount of polymerization inhibitor was changed from 0.001 g to 0.02 g and the type of adsorbent was changed from hydrotalcite to activated carbon, to obtain a purified residual (meth)acrylic-functional organosilicon compound. The amount of residual aluminum in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0038] [Example 8] The method of Example 1 was repeated to obtain a purified (meth)acrylic-functional organosilicon compound, except that the amount of polymerization inhibitor was changed from 0.001 g to 0.05 g and the thin-film distillation temperature was changed from 150 ° C to 140 ° C. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0039] [Example 9] The method of Example 1 was repeated to obtain a purified (meth)acrylic-functional organosilicon compound, except that the amount of polymerization inhibitor was changed from 0.001 g to 0.05 g and the thin-film distillation temperature was changed from 150 ° C to 130 ° C. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0040] [Example 10] The method of Example 1 was repeated except that the amount of polymerization inhibitor was changed from 0.001 g to 0.02 g, the temperature of thin-film distillation was changed from 150°C to 130°C, and the amount of hydrotalcite was changed from 1 mass% to 0.5 mass%, to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of aluminum remaining in the (meth)acrylic-functional organosilicon compound before and after the adsorption treatment is shown in Table 1.

[0041] [Comparative Example 1] The method of Example 1 was repeated, except that the amount of polymerization inhibitor was changed from 0.001 g to 0.01 g and the adsorption treatment step after thin-film distillation was omitted, to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of residual aluminum in the (meth)acrylic-functional organosilicon compound is shown in Table 1.

[0042] Comparative Example 2 The method of Example 1 was repeated except that the amount of polymerization inhibitor was changed from 0.001 g to 0.05 g and the adsorption treatment step after thin-film distillation was omitted, to obtain a purified (meth)acrylic-functional organosilicon compound. The amount of residual aluminum in the (meth)acrylic-functional organosilicon compound is shown in Table 1.

[0043] Comparative Example 3 The method of Example 1 was repeated, except that the polymerization inhibitor was changed from 0.001 g of N-nitroso-N-phenylhydroxylamine aluminum to 0.01 g of 2,6-di-tert-butyl-4-methylphenol and 0.01 g of 4-methoxyphenol, to obtain a purified (meth)acrylic-functional organosilicon compound. During thin-film distillation, gelation was observed within the distillation apparatus, so the purification was discontinued.

[0044] Comparative Example 4 100 g of the same (meth)acrylic-functional organosilicon compound as in Example 1 and 0.05 g of N-nitroso-N-phenylhydroxylamine aluminum were mixed and dissolved, and the mixture was subjected to vacuum distillation in a flask at 210°C and 0.5 kPa. During the distillation, gelation was observed in the flask, so the thin-film distillation was stopped. In vacuum distillation, polymerization cannot be suppressed even with the use of N-nitroso-N-phenylhydroxylamine aluminum.

[0045] The results of purification of the (meth)acrylic functional organosilicon compounds in the above Examples and Comparative Examples are shown in Table 1 below.

[0046] [Table 1]

[0047] As shown in Table 1 above, the purification method of the present invention can suppress gelation of the product when a (meth)acrylic-functional organosilicon compound is subjected to thin-film distillation, and can also provide a (meth)acrylic-functional organosilicon compound with a reduced amount of N-nitroso-N-phenylhydroxylamine aluminum mixed into the fraction after thin-film distillation.

Claims

1. A method for purifying (meth)acrylic-functional organosilicon compounds via thin-film distillation, comprising: The method includes the steps of: Step 1: thin-film distilling the crude product containing the (meth)acrylic functional organosilicon compound in the presence of N-nitroso-N-phenylhydroxylamine aluminum; Step 2: mixing the fraction containing the (meth)acrylic functional organosilicon compound obtained by the thin film distillation with hydrotalcite; and Step 3: filtering the hydrotalcite from the mixture to obtain a (meth)acrylic-functional organosilicon compound having an aluminum content of less than 1 ppm; The purification method as described above, wherein the amount of N-nitroso-N-phenylhydroxylamine aluminum in step 1 is 0.001 to 0.5 parts by mass per 100 parts by mass of the (meth)acrylic-functional organosilicon compound subjected to step 1.

2. A purification method as described in claim 1, wherein the thin film distillation in step 1 is carried out under a pressure in the range of 1 to 100 Pa.

3. A purification method as described in claim 1, wherein the increase in the kinetic viscosity of the residue in the distillation still after the thin film distillation relative to the kinetic viscosity of the fraction containing the (meth)acrylic functional organosilicon compound obtained by the thin film distillation in step 1 is +1.67 or more and +55 or less, when the kinetic viscosity of the fraction is set to 100.

4. A purification method as described in claim 1, wherein the thin film distillation in step 1 is carried out under an aerobic condition or under nitrogen.

5. 2. The purification method according to claim 1, wherein the amount of the hydrotalcite is 0.1 to 20 parts by weight per 100 parts by weight of the (meth)acrylic functional organosilicon compound subjected to step 2.

6. 2. The purification method according to claim 1, wherein the (meth)acrylic-functional organosilicon compound is a linear or branched organopolysiloxane having at least one (meth)acrylic-group-containing organic group in each molecule.

7. 7. The purification method of claim 6, wherein the (meth)acrylic functional organosilicon compound has a weight average molecular weight of 400 to 5,000.

8. 7. The purification method according to claim 6, wherein the (meth)acrylic functional organosilicon compound is represented by the following formula (1): 【Chemistry 1】 In the formula, R １ are each independently a monovalent hydrocarbon group having 1 to 8 carbon atoms, n is a number satisfying 0≦n≦50, and R ２ are each independently the R １ or a group represented by the following formula (2), ２ At least one of the groups is a group represented by the following formula (2): 【Chemistry 2】 (In the formula, R ３ is a divalent hydrocarbon group having 1 to 8 carbon atoms, and R ４ is a hydrogen atom or a methyl group, and x, y, and z are numbers from 0 to 30 and satisfy the relationship 0≦(x+y+z)≦30).

9. 9. The method according to claim 8, wherein in the formula (2), x, y, and z are numbers from 0 to 30 and satisfy the relationship 1≦(x+y+z)≦30.

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