JPH0139445B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a silicone-based graft copolymer. Several methods for producing silicone-based graft copolymers have been proposed in the past, such as those found in Japanese Patent Publication No. 32-6896, Japanese Patent Publication No. 16199-1982, Japanese Patent Publication No. 28389-1989, etc. A method of forming an active group by abstracting hydrogen from a lower alkyl group bonded to a silicon atom of silicone and grafting an organic polymer thereto (hereinafter abbreviated as hydrogen abstraction method for silicone), as described in Japanese Patent Publication No. 46-9355. , JP-A No. 52-135391, etc., there is a method in which silicone having an active group is produced in advance and an organic polymer is grafted onto the active group (hereinafter abbreviated as the method using silicone having an active group). be. Among these proposed methods for producing silicone-based graft copolymers, in the method based on hydrogen abstraction from silicone, hydrogen abstraction from lower alkyl groups bonded to silicon atoms is an essential condition for producing the graft copolymer. Therefore, a method and conditions suitable for abstracting hydrogen from the lower alkyl group bonded to the silicon atom of silicone are first required. A commonly used method is to cause a heating reaction between silicone, a monomer capable of forming the polymer to be grafted onto the silicone, and an organic peroxide. The type, amount, and reaction temperature must be carefully selected. For example, as for catalysts, azo-based initiators such as azobisisobutyronitrile have a low ability to abstract hydrogen from silicone, resulting in low grafting efficiency and cannot normally be used. Generally, peroxides represented by ROOH or ROOR (R is an organic group) are used, such as benzoyl peroxide, di-t-butyl peroxide,
T-butyl hydroperoxide, cumene hydroperoxide, etc. are used, but the ease with which hydrogen can be abstracted from silicone varies depending on the type of these peroxides. Furthermore, although the reaction temperature is above the decomposition temperature of the organic peroxide used, the ease with which hydrogen can be abstracted from silicone is affected by the temperature, and at the same time, the molecular weight of the organic polymer to be grafted is also affected. It is difficult to control the influence well, and furthermore, the crosslinking reaction may proceed and gelation may occur during the reaction, making it impossible to obtain a graft copolymer with a clear structure. That is, the molecular weight and number of organic polymers grafted per silicone molecule may differ, and unreacted silicone that is not grafted may be included. On the other hand, in the case of a method using silicone having an active group, for example, according to the method disclosed in Japanese Patent Publication No. 46-9355, a silicone having an active group is reacted with a living polymer obtained by anionic polymerization. Although a silicone-based graft copolymer can be obtained, the structure using anionic polymerization is troublesome, it is necessary to select monomers that are easy to undergo anionic polymerization, and the production cost is high, so it is by no means satisfactory. Furthermore, according to the method disclosed in Japanese Patent Publication No. 52-135391, a polysiloxane polyester containing maleic acid in the main chain is synthesized, and an electron-donating monomer that easily forms a charge transfer complex with maleic acid is added to the polysiloxane polyester. A silicone-based graft copolymer can be obtained by mixing and graft polymerizing, but there are restrictions on the monomers used. The present invention was achieved as a result of intensive research in view of the methods for producing silicone-based graft copolymers that have been proposed up to now, in order to overcome the drawbacks of known methods. That is, the present invention uses an acrylic-modified silicone, which is a condensation reaction product of a silicone represented by the general formula (A) below, and an acrylic compound represented by the general formula (B), and a radically polymerizable comonomer. Comonomer copolymerization ratio 90~
This is a method for producing a graft copolymer, characterized in that radical copolymerization is carried out using an azo polymerization initiator at a weight ratio of 10:10 to 90 (weight ratio).

[Formula] (R ¹ and R ² are monovalent aliphatic hydrocarbon groups, phenyl groups, or monovalent halogenated hydrocarbon groups with 1 to 10 carbon atoms. n is a positive number of 1 or more.)

[Formula] (R ³ is a hydrogen atom or a methyl group. ^{R 4} is a methyl group, ethyl group, or phenyl group. X is a chlorine atom, a methoxy group, or an ethoxy group.) Currently, various types of silicone are readily available, and one can be used depending on the purpose. Substituents R ¹ and R ² present on the silicon atom have 1 carbon number
~10 monovalent aliphatic hydrocarbon groups, phenyl groups, or monovalent halogenated hydrocarbon groups, preferably methyl groups. Further, n is a positive number of 1 or more. The molecular weight of the silicone represented by the general formula (A) can be selected depending on the purpose, and in general, when an acrylic modified silicone derived from a silicone with a large molecular weight where n is 100 or more and a radically polymerizable monomer are copolymerized, An oil-like graft copolymer is obtained, and in the copolymerization of an acrylic-modified silicone derived from a low molecular weight silicone with n of 100 or less and a radically polymerizable monomer, an oil-like or jelly-like graft copolymer is obtained depending on the type of monomer used. , various types of graft copolymers such as solid can be obtained, but if n is too small, when the obtained silicone graft copolymer is used as a paint, for example, the effects of silicone, i.e., water repellency, oil repellency, low friction If it is too large, the obtained silicone graft copolymer will become oily and difficult to purify, so n is generally 1 or more and 500 or less.
Preferably it is 10 or more and 300 or less. Examples of the acrylic compound represented by the general formula (B) include γ-methacryloxypropylmethyldichlorosilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylphenyldichlorosilane, γ-methacryloxypropylethyl Dichlorosilane, γ-
Examples include acryloxypropylmethyldichlorosilane. These acrylic compounds are generally well known and can be easily obtained by reacting a silicon compound and a compound having an aliphatic multiple bond in the presence of chloroplatinic acid according to the method disclosed in Japanese Patent Publication No. 33-9969. For example, when the acrylic compound is γ-methacryloxypropylmethyldichlorosilane, it can be obtained by reacting allyl methacrylate and methyldichlorosilane in the presence of chloroplatinic acid. The reaction between the silicone represented by the general formula (A) and the acrylic compound represented by the general formula (B) proceeds extremely smoothly according to ordinary organic chemical reaction operations. For example, X of an acrylic compound represented by general formula (B)
When is a chlorine atom, add an acrylic compound represented by general formula (B) to a solution in which silicone represented by general formula (A) and an acid acceptor are dissolved in an appropriate solvent shown below at a concentration of 10 to 50% by weight. Alternatively, if a solution prepared by dissolving this in a suitable solvent shown below at a concentration of 10 to 50% by weight is added dropwise at room temperature, the reaction will immediately proceed smoothly. After the reaction, the produced acid acceptor hydrochloride is filtered out, and then, if necessary, washed with water and the solvent is evaporated to obtain the desired acrylic-modified silicone. The solvent that can be used in this reaction is preferably a solvent that dissolves both reaction components and is inert to both reaction components under the reaction conditions. Suitable solvents include, for example, diethyl ether, tetrahydrofuran, acetone, benzene, toluene, xylene,
Examples include mineral spirits. As the acid acceptor, known amines can be used, and for example, pyridine, triethylamine, aniline, etc. are preferably used. The amount of acid acceptor used is preferably about 1.2 times the molar amount of hydrochloric acid produced by the dehydrochlorination reaction. When X of the acrylic compound represented by general formula (B) is a methoxy group or an ethoxy group, general formula (A)
The silicone represented by the formula (B) and the acrylic compound represented by the general formula (B) may be mixed and subjected to a dealcoholization condensation reaction. In this case, catalysts conventionally used in transesterification reactions, such as isopropyl orthotitanate, sulfuric acid, P-toluenesulfonic acid, acetic trifluoride, and dibutyltin dilaurate, can be used to accelerate the reaction. The amount of catalyst is desirably about 0.1 to 5% by weight based on the total amount of silicone and acrylic compound. Further, the reaction temperature is preferably 50°C or higher, and generally a temperature of around 100°C is adopted. As mentioned above, acrylic-modified silicone is obtained by the reaction of silicone represented by general formula (A) (hereinafter simply referred to as silicone) and an acrylic compound represented by general formula (B) (hereinafter simply referred to as acrylic). However, the reaction molar ratio between the two can be freely selected depending on the purpose. For example, if you want to obtain an oil-like silicone-based graft copolymer that can be used as a sealant, it depends on the type of monomer used when radically copolymerizing acrylic-modified silicone and a radically polymerizable monomer, Therefore, it is preferable to use an acrylic-modified silicone which has a large molecular weight, and the properties of the silicone-based graft copolymer obtained by doing so have little to do with the reaction molar ratio of silicone and acrylic during the production of the acrylic-modified silicone. Although there is no
Generally, the reaction molar ratio of silicone and acrylic is 0.45 to 1.1 mol of acrylic to 1 mol of silicone.
Preferably 0.5 acrylic to 1 mole of silicone
~1.0 mol is good. If the reaction molar ratio is less than 0.45, there will be a large amount of unreacted silicone, and if it exceeds 1.1, it will be difficult to purify the resulting silicone-based graft copolymer, and since acrylic is expensive, the resulting silicone-based graft copolymer will be difficult to purify. It becomes expensive. On the other hand, when it is desired to obtain a silicone-based graft copolymer that can be dissolved in solvents used in organic solvent-based paints, such as toluene, xylene, acetone, and thinner, an acrylic-modified silicone and a radically polymerizable monomer are radically copolymerized. In this case, it is necessary that the reaction molar ratio of silicone and acrylic is 0.25 to 1 mol of acrylic to 1 mol of silicone. A silicone-based graft copolymer that tends to gel when radically copolymerized with a radically polymerizable monomer using an acrylic-modified silicone obtained by a reaction molar ratio of more than 1 mole of acrylic to 1 mole of silicone, and can be dissolved in a solvent. It will be difficult to obtain. Furthermore, when a silicone-based graft copolymer is obtained by radical copolymerization with a radically polymerizable monomer using an acrylic-modified silicone obtained from a reaction molar ratio of less than 0.25 mole of acrylic to 1 mole of silicone, the acrylic is not condensed. A large amount of silicone (hereinafter referred to as unreacted silicone) remains in the silicone-based graft copolymer, which is not preferable. In this way, the reaction molar ratio of silicone and acrylic is appropriately selected depending on the intended use. In addition, the unreacted silicone contained in the acrylic-modified silicone is directly subjected to radical copolymerization with a radically polymerizable monomer in the next step, and after obtaining a silicone-based graft copolymer, it can be recovered as necessary. can. In that case, the amount of acrylic used can be reduced to 0.25 mol. The thus obtained acrylic-modified silicone suitable for the intended use has extremely high polymerizability, and copolymerization proceeds extremely smoothly with most conventional radically polymerizable monomers.
A silicone-based graft copolymer can be easily obtained, and its molecular weight can be controlled by known polymerization techniques. In the present invention, the radically polymerizable comonomer (hereinafter simply referred to as a monomer) to be copolymerized with the acrylic-modified silicone includes low molecular weight linear unsaturated hydrocarbons such as ethylene, propylene, butylene, chlorinated vinyl and halogenated vinyl such as vinyl fluoride;
Vinyl esters of organic acids such as vinyl acetate, styrene, styrene substitutes, and other vinyl aromatic compounds such as vinylpyridine and vinylnaphthalene, acrylic acid, methacrylic acid, and esters, amides, and acrylonitrile thereof; Examples include acid derivatives, N-vinyl compounds such as N-vinylcarbazole, N-vinylpyrrolidone and N-vinylcaprolactam, and vinyl silicon compounds such as vinyltriethoxysilane. Di-substituted ethylene can also be used,
Examples include vinylidene fluoride, vinylidene chloride, and esters of maleic anhydride, maleic acid, and fumaric acid. The monomers can be used alone or in combination of two or more types. The radical copolymerization ratio of acrylic modified silicone and monomer is 10 to 90% for acrylic modified silicone.
The proportion of the monomer is 90 to 10 parts by weight, and the copolymerization ratio can be selected from a wide range depending on the intended use. In the present invention, it is necessary to radically copolymerize the acrylic-modified silicone and the monomer in the presence of an azo polymerization initiator, and such polymerization can be carried out by a solution polymerization method using a solvent, a bulk polymerization method, an emulsion polymerization method, etc. It can be done with The azo polymerization initiator has a chemical structure in which a tertiary carbon atom having a nitrile, carboxyalkyl, cycloalkylene, or alkyl group having 1 to 18 carbon atoms as a substituent is bonded to both nitrogen atoms of an azo bond. An azo compound having the following is preferred, and azobisisobutyronitrile (hereinafter abbreviated as AIBN) is most preferred. The amount of the azo polymerization initiator is generally 0.01 to 5% by weight, preferably 0.1 to 5% by weight based on the total weight of the polymerization components.
It is 2% by weight. The radical copolymerization temperature is preferably higher than the decomposition temperature of the azo polymerization initiator, but if the reaction temperature is too high, undesirable reactions such as crosslinking will occur, making it difficult to obtain a silicone-based graft polymer with a clear structure. Therefore, a temperature as low as possible is preferred. Generally the polymerization temperature is 50-100℃, preferably 60℃
~90℃. Polymerization time is generally 3 to 100 hours, preferably
10-25 hours. is the most suitable initiator in the method of the invention
When acrylic-modified silicone and monomer are radically copolymerized using AIBN, in addition to being able to easily obtain a silicone-based graft copolymer, the initiator AIBN has low hydrogen abstraction activity from silicone, and Since the temperature is low, unreacted silicone can exist in the silicone-based graft copolymer in the state of general formula (A) after polymerization, and such unreacted silicone can be mixed with n-hexane, mineral spirits, etc. As a result, a highly pure silicone-based graft copolymer from which unreacted silicone has been removed, as shown in Example 11 below, is obtained, and the above-mentioned By being able to set the polymerization temperature to a low value, undesirable reactions such as crosslinking reactions during polymerization can be suppressed. That is, one embodiment of the present invention is to react an acrylic-modified silicone produced from silicone and acrylic with a monomer by radical copolymerization,
This is a method for producing a silicone-based graft copolymer, which comprises the steps of producing a silicone-based graft copolymer and then recovering unreacted silicone in the graft copolymer. The unreacted silicone can be recovered by extracting the solvent-insoluble silicone graft copolymer and the solvent-soluble silicone using a conventional method. The thus obtained silicone-based graft copolymer is a graft copolymer in which a polymer obtained from monomers (hereinafter referred to as an organic polymer) forms a trunk portion, and components containing silicone units form branch portions, Since the component containing silicone units is not bonded to the organic polymer through bonds such as Si--O--C, it is extremely stable against hydrolysis. The number of branch points in the generated graft copolymer can be determined by the molecular weight of the acrylic-modified silicone used, the molecular weight of the monomer, the molecular weight of the silicone-based graft copolymer, and the silicone content in the silicone-based graft copolymer. . The molecular weight of the silicone unit that is the branch part of the silicone-based graft copolymer obtained according to the method of the present invention depends on the type of acrylic-modified silicone used, and the molecular weight of the silicone that is the raw material for producing the acrylic-modified silicone [the general formula (A ) can be easily controlled by appropriately selecting the value of n in ), and polymerization can be performed at low temperatures using a particularly preferred polymerization initiator such as AIBN, thereby preventing undesirable graft polymerization caused by hydrogen abstraction from silicone. Almost no cross-linking reaction occurs,
Furthermore, the molecular weight of the silicone-based graft copolymer produced can be easily controlled by using a commonly used chain transfer agent. As described above, the method of the present invention can produce various silicone-based graft copolymers through extremely simple operations, and has extremely high industrial value. In addition, since the silicone-based graft copolymer obtained by the method of the present invention contains silicone unit-containing components in the copolymer, which contain silanol units at their terminals, the silicone-based graft copolymer obtained by the method of the present invention is suitable for use with commonly used terminal-silanol type silicone crosslinking agents and crosslinking promoters. The silanol units can also be crosslinked by using a compound, and the silanol units are also highly compatible with other polar compounds. Furthermore, the silicone-based graft copolymer obtained by the method of the present invention can be used as a raw material or surface modifier for sealants, various plastic films, molded products, fibers, rubber, paints, adhesives, etc., and has excellent water resistance and heat resistance. It can provide the properties of silicone, such as weather resistance. For example, by adding and dissolving the silicone-based graft copolymer obtained in the present invention in an organic solvent-based paint, it is possible to impart excellent water and oil repellency, stain resistance, and low friction properties to the coating surface. . Next, Examples and Comparative Examples will be given to explain the present invention more specifically. Example 1 α,ω-dihydroxydimethylpolysiloxane

In a solution of 220 g (0.01 mol) of silicone whose average n is 300] and 0.949 g (0.012 mol) of pyridine dissolved in 400 ml of diethyl ether,
A 10% diethyl ether solution containing 1.21 g (0.005 mol) of γ-methacryloxypropylmethyldichlorosilane was gradually added dropwise at room temperature over 20 minutes. The reaction proceeded immediately and white crystals of pyridine hydrochloride were precipitated. After the dropwise addition was completed, the mixture was further stirred at room temperature for 1 hour, and the crystals of pyridine hydrochloride were removed by filtration. Next, pour this liquid into a separating funnel and add water.
Add 500 ml, shake well, and wash with water. After washing with water, the separatory funnel was left standing to separate the upper ether layer and the lower aqueous layer, and anhydrous sodium sulfate was added to the obtained ether layer, which was then left at room temperature overnight to dehydrate. Thereafter, anhydrous sodium sulfate was removed by filtration, and the resulting liquid was distilled under reduced pressure to remove ether, yielding 200 g of a colorless and transparent acrylic-modified silicone. Next, 20 parts of the obtained acrylic modified silicone, 30 parts of styrene, and azobisisobutyronitrile (hereinafter referred to as
(referred to as AIBN) and 60 parts of toluene were placed in a flask equipped with a condenser and a stirrer and reacted at a temperature of 80°C for 24 hours in a nitrogen atmosphere. After the reaction is complete, the contents of the flask are poured into a large amount of methanol,
A polymer was obtained by precipitating the polymer.
After drying under reduced pressure, 47 parts of a uniform white oil-like silicone-based graft copolymer was obtained. This silicone-based graft copolymer remained in the form of a uniform white oil even when stored at room temperature for more than two months. Examples 2 to 4 The acrylic modified silicone obtained in Example 1 was copolymerized with various monomers shown in Table 1. For copolymerization, add acrylic modified silicone 5 to a test tube.
1 part, 5 parts of each monomer, and 0.05 part of AIBN were added, mixed well, and reacted for 24 hours at a temperature of 80°C in a nitrogen atmosphere. The properties of the obtained silicone-based graft copolymer are also shown in Table-1.

[Table] Examples 5 to 7 α,ω-dihydroxydimethylpolysiloxane

γ-methacryloxypropylmethyldichlorosilane was added to a solution of 244 g (0.4 mol) of silicone with an average of 8 in the formula and 38 g (0.48 mol) of pyridine dissolved in 400 ml of diethyl ether.
48.24 g (0.2 mol) of a 10% diethyl ether solution was gradually added dropwise at room temperature over 20 minutes. Thereafter, 275 g of acrylic modified silicone was obtained in the same manner as in Example 1. The obtained acrylic modified silicone was copolymerized with various monomers shown in Table 2. Copolymerization was carried out in the same manner as in Examples 2-4. The properties of the silicone graft copolymer obtained are also shown in Table 2.

[Table] Examples 8 to 10 α,ω-dihydroxydimethylpolysiloxane

220g (0.1 mol) of silicone with average n of formula 30] and 19.0g (0.24 mol) of pyridine
In a solution of γ in 400 ml of diethyl ether,
- A 10% diethyl ether solution of 24.1 g (0.1 mol) of methacryloxypropylmethyldichlorosilane was gradually added dropwise at room temperature over 20 minutes. After that, acrylic modified silicone was added in the same manner as in Example 1.
Obtained 225g. This acrylic modified silicone and butyl methacrylate were copolymerized at each ratio shown in Table 3. Copolymerization for acrylic modified silicone, butyl methacrylate and mixtures thereof in test tubes
0.5% AIBN was added and heated at 80°C for 6 hours under a nitrogen atmosphere. The properties of the obtained silicone graft copolymer are also shown in Table 3.

[Table] Example 11 α,ω-dihydroxydimethylpolysiloxane [

220 g (0.1 mol) of silicone with average n of [formula] 30] and 9.52 g (0.12 mol) of pyridine
In a solution of γ in 400 ml of diethyl ether,
-Methacryloxypropylene A 10% diethyl ether solution of 12.06 g (0.05 mol) of methyldichlorosilane was gradually added dropwise at room temperature over 20 minutes. Thereafter, 225 g of acrylic modified silicone was obtained in the same manner as in Example 1. Next, 50 parts of the acrylic modified silicone, 50 parts of methyl methacrylate, AIBN1.0
and 300 parts of toluene were placed in a flask equipped with a condenser and a stirrer, and heated at a temperature of 80°C in a nitrogen atmosphere.
The reaction was allowed to proceed for 24 hours. After the reaction, toluene and unreacted methyl methacrylate were removed by vacuum distillation to obtain a solid reaction product. Unreacted acrylic-modified silicone was extracted from the reaction product with n-hexane and dried under reduced pressure to obtain 81 parts of a white powdery silicone-based graft copolymer. This silicone-based graft copolymer was soluble in toluene, xylene, and thinner. Also, as a result of analysis, the amount of silicone contained in this silicone-based graft copolymer was 40%.
It was hot. For analysis of silicone, approximately 0.2 g of silicone-based graft copolymer was accurately weighed in a platinum crucible, approximately 3 ml of concentrated sulfuric acid was added, and the mixture was placed in an electric furnace and heated at 700° C. for 2 hours to determine silicone as SiO ₂ . Comparative Examples 1-3 Copolymerization was carried out in the same manner as in Examples 2-4 using the α,ω-dihydroxydimethylpolysiloxane used in Example 1 and the same monomers as in Examples 2-4. The results are shown in Table 4. Note that Comparative Examples 1 to 3 correspond to Examples 2 to 4, respectively.

[Table] If acrylic modified silicone is not used,
A uniform polymer as shown in the table above cannot be obtained. Comparative Examples 4-6 Copolymerization was carried out in the same manner as in Examples 2-4 using the α,ω-dihydroxydimethylpolysiloxane used in Examples 5-7 and the same monomers as in Examples 2-4. The results are shown in Table-5. Note that Comparative Examples 4 to 6 correspond to Examples 5 to 7, respectively.

[Table] If acrylic modified silicone is not used, a uniform polymer as shown in the above table cannot be obtained. Comparative Example 7 α,ω-dihydroxydimethylpolysiloxane [

[Formula] n is 300 on average] 100 parts silicone, 83 parts styrene, 67 parts butyl acrylate,
and 0.75 parts of di-t-butyl peroxide were placed in a flask equipped with a condenser and a stirrer, and reacted in a nitrogen atmosphere at a temperature of 122°C for 7 hours. A small amount of unreacted monomer was removed under reduced pressure of 1 mmHg at 80°C. The reaction product was a white highly viscous oil,
When stored in a container at room temperature for two months, the oil was non-uniform, with a hard oil in the lower layer and a soft oil in the upper layer. Further, even when attempting to dissolve the reaction product in toluene, there were undissolved substances, resulting in a cloudy toluene solution.

Claims (1)

[Claims] 1 Silicone represented by the following general formula (A) and the general formula
The acrylic modified silicone, which is the condensation reaction product with the acrylic compound shown in (B), and the radically polymerizable comonomer are copolymerized at a copolymerization ratio of 90 to 10 to 10 to 90.
A method for producing a graft copolymer, which comprises carrying out radical copolymerization using an azo polymerization initiator at (weight ratio). (R ¹ and R ² are monovalent aliphatic hydrocarbon groups with 1 to 10 carbon atoms, phenyl groups, or monovalent halogenated hydrocarbon groups. n is a positive number of 1 or more.) (R ³ is a hydrogen atom or a methyl group. ^{R 4} is a methyl group,
Ethyl group or phenyl group. X is a chlorine atom, a methoxy group or an ethoxy group. )