JP2697869B2 - Method for producing comb copolymer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a high molecular weight comb copolymer useful as an elastomer or a molding material.

[Conventional technology]

Block copolymers and graft copolymers have been developed for the purpose of enhancing the functionality and performance of polymer materials.In recent years, oligomers and polymers having a polymerizable functional group at one end have been developed. Due to advances in synthetic technology, interest has been drawn to the development and application of comb copolymers using this. The most common method of synthesizing a comb copolymer of such an oligomer or polymer and a normal vinyl monomer is a solution polymerization method in which both the polymerization initiators are dissolved in a suitable solvent and polymerized. . There is also known a method in which the above oligomer or polymer and a polymerization initiator are dissolved in a vinyl monomer to perform bulk polymerization or suspension polymerization.

[Problems to be solved by the invention]

However, although the solution polymerization method has an advantage that polymerization is easy, there is a problem that chain transfer to a solvent easily occurs, and therefore, it is difficult to produce a high molecular weight comb copolymer,
It has been difficult to adopt it for applications requiring mechanical uses, such as elastomers and molding materials. In addition, the method of performing bulk polymerization or suspension polymerization by dissolving an oligomer or polymer in a vinyl monomer has the advantage that a high molecular weight polymer is easily obtained as compared with the solution polymerization method. Since the solubility is limited, there is a problem that it is difficult to obtain a comb copolymer having a high ratio of the oligomer and polymer components.

Thus, while aiming at the production of a unique copolymer called a comb copolymer in the prior art, due to restrictions on the production technology, only a low-molecular-weight copolymer or a copolymer with a high ratio of vinyl monomer components can be obtained. Therefore, conventionally, the characteristics of the comb copolymer cannot be sufficiently enjoyed.

In view of such a situation, the present inventors have conducted intensive studies on a method for producing a comb copolymer without such restrictions, and as a result, the oligomer or polymer and a vinyl monomer were used as a good solvent at 30 ° C. It has been found that the above-mentioned object can be achieved by mixing with a polymerization initiator in a solvent which dissolves in water in an amount of 10% by weight or more, and subjecting the mixture to aqueous suspension polymerization. As a result of further study, even if the solubility in water at 30 ° C. was less than 10% by weight, a specific halogenated solvent was used as a solvent for the suspension polymerization of the above-mentioned comb copolymer under specific polymerization conditions. The present inventors have found that a hydrocarbon solvent can be used, and the above object can be achieved by such a method, and the present invention has been accomplished.

[Means for solving the problem]

That is, the method for producing the comb copolymer of the present invention comprises a polymer having a vinyl group at one end and a number average molecular weight of 3,000 to 50,000 and a vinyl monomer, a good solvent for the polymer, and 30 to 90 ° C. Mixed with a polymerization initiator in a halogenated hydrocarbon solvent having an azeotropic point with water in a temperature range of, and the mixture is subjected to aqueous suspension polymerization at a temperature equal to or higher than the azeotropic point with water of the solvent. I do.

[Action]

The number average molecular weight of the polymer having a vinyl group at one end (hereinafter, referred to as a macromonomer) used in the method of the present invention needs to be 3,000 to 50,000. Even if a macromonomer having a molecular weight of less than 3,000 is used, a comb copolymer having sufficient properties cannot be obtained, and a molecular weight of 5,000
A macromonomer exceeding 0 is not preferable because reactivity becomes low.

The monomer unit constituting the main chain of the macromonomer may be a normal vinyl monomer, and examples thereof include various methacrylates, acrylates, and styrene. Two or more of these monomers may be used. Such a macromonomer is obtained by, for example, conducting anionic living polymerization such as methyl methacrylate (MMA) and then reacting with a halogen-containing vinyl compound; performing radical polymerization of the vinyl monomer in the presence of mercaptoacetic acid, and then obtaining A method in which a polymer or oligomer is reacted with a glycidyl group-containing monomer such as glycidyl methacrylate; by a method in which a vinyl monomer such as MMA is polymerized using vinylphenylketenetrimethylsilyl acetal as an initiator and reacted with paravinylbenzyl or halogen-containing vinyl. Can be.

This macromonomer constitutes a branch in the comb copolymer produced by the method of the present invention.

On the other hand, as the vinyl monomer used in the method of the present invention, any general vinyl monomer capable of radical polymerization can be used, and acrylates, methacrylates, styrene, acrylonitrile and the like are typical. Can be exemplified. These vinyl monomers may be used as a mixture of two or more. However, considering the purpose of forming the comb copolymer, it is preferable to use a monomer of a type different from the monomer component forming the main chain of the macromonomer as the vinyl monomer.

The solvent used in the method of the present invention is a good solvent for the macromonomer that sufficiently dissolves the macromonomer, and is insoluble in water (the solubility in water at 30 ° C is less than 10% by weight).
However, it is necessary that the halogenated hydrocarbon has an azeotropic point with water in a temperature range of 30 to 90 ° C, more preferably 30 to 80 ° C. Representative examples of such solvents include chloroform and 1,2-dichloroethane.

When the solvent used does not have an azeotropic point with water at 90 ° C. or lower, even when the polymerization system is heated to about 90 ° C. during polymerization, it is heated only to a temperature lower than the azeotropic point of the solvent. Therefore, the solvent in the suspended particles is not removed. Therefore,
A considerable amount of solvent remained in the vicinity of the monomer being polymerized, resulting in chain transfer, making it difficult to obtain a high-molecular-weight polymer, or a large amount of solvent remaining in the produced polymer. The fusion of the polymer or the like occurs and handling becomes difficult.

A solvent having an azeotropic point with water of less than 30 ° C. starts azeotropy at almost normal temperature, which makes it difficult to handle the polymerization system and is not suitable.

In addition, as a solvent to be used, not all solvents having an azeotropic point with water in a temperature range of 30 to 90 ° C. can be used, and only a halogen-based solvent can be used. Although the reason for this has not yet been fully elucidated, factors such as the ratio of the solvent in the azeotrope, the boiling point and vapor pressure of the solvent alone, the solubility in water, and the affinity for the formed polymer are involved. It is estimated that These non-halogen solvents, even those having an azeotropic point with water in the vapor range, are not suitable because many of them cause fusion of the polymer.

In the method of the present invention, the ratio between the macromonomer and the vinyl monomer can be set to an arbitrary range depending on the desired comb copolymer, but from 95/5 to 10/90.
And more preferably in the range of 90/10 to 30/70. When the proportion of the macromonomer exceeds 95% by weight, it becomes difficult to obtain a high molecular weight polymer even in the method of the present invention, and when it is less than 10% by weight, the method of the present invention in which a solvent is mixed and used is not used. In many cases, suspension polymerization is possible, so that the merit of employing the method of the present invention is reduced.

It is preferable to use 30 to 300 parts by weight of the halogenated hydrocarbon solvent based on 100 parts by weight of the macromonomer. If the amount of the solvent is less than 30 parts by weight, a sufficient dilution effect cannot be obtained, and it becomes difficult to sufficiently dissolve the macromonomer in the vinyl monomer. On the other hand, when the amount is more than 300 parts by weight, it becomes difficult to produce a high molecular weight polymer, and the polymerization stability is lowered.

As the polymerization initiator, ordinary initiators for radical polymerization can be used. Preferred examples thereof include peroxide initiators such as benzoyl peroxide and lauroyl peroxide, and azo initiators such as azobisisobutyronitrile. it can.

Further, if necessary, a chain transfer agent such as n-octyl mercaptan cannot be used, but it is desirable to limit the use amount within a range where the molecular weight does not decrease significantly.

In the present invention, the macromonomer, the vinyl monomer, and the radical polymerization initiator are mixed in the halogenated hydrocarbon solvent to form a uniform solution, and the mixture is poured into a dispersion stabilizer and water, and sufficiently stirred. To form a suspension, and polymerization may be performed in this state.

In the method of the present invention, the polymerization of the aqueous suspension,
The reaction is performed at a temperature equal to or higher than the azeotropic point of the solvent. However, the polymerization temperature does not need to be equal to or higher than the above azeotropic point during the entire period from the start of polymerization to the end of polymerization.However, at least until the time period near the end of polymerization, the solvent in the suspended particles is azeotropic with water. Must be kept at a temperature equal to or higher than the azeotropic point for a time sufficient for almost complete removal.

The ratio of the amount of water to the total amount of the macromonomer and the vinyl monomer and water may be any amount that does not affect the stability of the polymerization, and is preferably monomer / water = 1 / 1.5 to 1/6, It is more preferable that the ratio be from / 3 to 1/5.

According to the method of the present invention, the resulting comb copolymer is
As in the case of ordinary suspension polymerization, it is obtained as polymer particles having a particle size of 10 μm to 2 mm. Thus, after cooling the reaction system, the polymer may be recovered by filtration, dehydration, and washing. When the type of the solvent used and the temperature at the time of polymerization satisfy the requirements specified in the present invention, the resulting polymers are obtained as particles having a uniform particle size without fusing each other.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.

 In the examples, "parts" means parts by weight.

Further, the molecular weight shown in the examples, the value of the molecular weight distribution,
It is the molecular weight in terms of polystyrene determined by the GPC method under the following conditions.

GPC prescribed conditions: Apparatus: 201D compact type (manufactured by Waters) Column: TSK gel GMHXL + 4000HXL + 2500HXL Solvent: tetrahydrofuran Temperature: 30 ° C. Flow rate: 0.7 ml / min Sample concentration: about 1% Detector: Differential refractometer Example 1 Powdery 50 parts of polymethyl methacrylate-based macromonomer (AA-6, manufactured by Toa Gosei Chemical Industry Co., Ltd., Mn = 6000) and 0.3 part of n-octyl mercaptan are mixed with 50 parts of chloroform (azeotropic point with water = 50 ° C.) and acrylic. After adding and dissolving in a mixed solution with 50 parts of butyl acid to form a uniform solution, 1 part of lauryl peroxide was added as a polymerization initiator,
Stir and mix to prepare a uniform monomer / initiator solution.

400 parts of ion-exchanged water, 1 part of a calcium phosphate dispersion stabilizer and 151.3 parts of the above monomer / initiator solution were charged into a reaction vessel equipped with a stirrer, a cooling pipe, and a nitrogen gas introduction pipe. After the inside of the reaction system was sufficiently purged with nitrogen, the temperature of the reaction system was increased to 70 ° C. with stirring to start polymerization. After polymerization at 70 ° C. for 3 hours, the temperature of the reaction system was raised to 90 ° C. over 1 hour, and further kept at that temperature for 1 hour to complete the polymerization.

After the temperature of the reaction system was cooled to 40 ° C., it was separated by filtration, washed, dehydrated, and dried at 70 ° C. overnight to obtain a beaded polymer. The average particle size of the obtained polymer was about 120 μm, there was no mutual adhesion of the particles, and the polymer was extremely good as a suspension-polymerized particle. PMMA (branch) -PBuA thus obtained
(Stem) The comb-shaped copolymer had a number average molecular weight of 82,000 and a molecular weight distribution of 2.5.

Example 2, Comparative Examples 1-3 PMMA was completely the same as Example 1 except that the solvent shown in Table 1 was used instead of chloroform.
A (branch) -PBuA (trunk) comb copolymer was synthesized.
The results are as shown in Table 1. In the case of a solvent other than a halogenated hydrocarbon, the molecular weight of the obtained comb copolymer was 90 ° C. or less even if it had an azeotropic point with water. Satisfactory results were not obtained because of low adhesion, adhesion during polymerization or drying.

[Effects of the Invention] According to the production method of the present invention, the ratio of the macromonomer constituting the branch portion of the comb copolymer and the vinyl monomer constituting the trunk portion can be selected in a wide range, and has a considerably high molecular weight. Production of a comb copolymer has become possible. As a result, the structural range of the combiform copolymer that can be produced is greatly expanded, and the excellent properties of the comb copolymer can be sufficiently enjoyed.

Claims (1)

(57) [Claims] 1. A number average molecular weight of 30 having a vinyl group at one end.
A polymer of from 00 to 50000 and a vinyl monomer are mixed with a polymerization initiator in a halogenated hydrocarbon solvent which is a good solvent for the polymer and has an azeotropic point with water in a temperature range of 30 to 90 ° C., A process for producing a comb copolymer, comprising subjecting the mixture to aqueous suspension polymerization at a temperature not lower than the azeotropic point with water of the solvent.