JPH0737503B2 - Production method of block copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for making block copolymers. More specifically, it is characterized by radically polymerizing a radically polymerizable monomer (excluding vinyl ester) in the presence of a polymer having a mercapto group only at its terminal (excluding polyvinyl alcohol polymer and polyvinyl ester polymer). The present invention relates to a method for producing a block copolymer.

Block copolymers, which consist of bonds of polymer components with different properties, have various different physical properties according to the variety of combinations of copolymer components, such as impact-resistant resins, polymeric emulsifiers, dispersants, etc. In addition to its use as a graft copolymer, it has recently attracted attention as a membrane material and a medical material, and its research examples span a wide range along with graft copolymers.

As a method for synthesizing the block copolymer, ionic polymerization is generally used, and several methods have been proposed as radical polymerization, but the method is not necessarily general.

As a result of earnest studies on a method for easily obtaining a block copolymer by radical polymerization, the present inventors have found that only a terminal (in the following description, “terminal” means “terminal only”) a mercapto group. A radical-polymerizable monomer in the presence of a polymer (excluding a polyvinyl alcohol-based polymer and a polyvinyl ester-based polymer. The same applies to the following description) (excluding vinyl ester. The same applies to the following description). The inventors have found that a block copolymer can be produced by radically polymerizing the above, and have completed the present invention.

The polymer having a mercapto group at the terminal used in the present invention,
It can be obtained by the following method. The first method is a method of converting a polymer having a hydroxyl group at a terminal into a mercapto group by a chemical reaction, for example, after changing the hydroxyl groups at both terminals of polyethylene glycol or polypropylene glycol into a halide or a sulfonate, a thiourea is added. Then, an isothiuronium salt is prepared and hydrolyzed with an alkali. The second method is a method by polycondensation with a combination of dithiol and diamine, dithiol and diisocyanate and the like. The third method is to radically polymerize a radically polymerizable monomer in the presence of a thiol acid such as thiol acetic acid and treat the resulting polymer with an alkali or an acid to introduce a mercapto group at one end of the molecule. Is the way to do it. For example, radical polymerization of methyl methacrylate, styrene, etc. in the presence of thiolacetic acid,
By treating with an alkali or an acid, polymethylmethacrylate having a mercapto group at the terminal, polystyrene or the like can be synthesized. In addition to this, there are various methods for introducing a mercapto group at the terminal of the polymer, but the present invention does not impose any limitation on these synthetic methods, and a polymer having a mercapto group at the terminal can be used. .

The feature of the production method of the present invention is to perform radical polymerization in the presence of a polymer having a mercapto group at the terminal,
As a polymerization method for achieving the object of the present invention, a generally known method, for example, any of bulk polymerization, solution polymerization, pearl polymerization and emulsion polymerization can be adopted, but a polymerization method having a mercapto group at a terminal is used. A suitable polymerization method can be selected depending on the nature of the coalescence. In addition, as the polymerization process, it is possible to manufacture by a batch method, a semi-batch method, or a continuous method. That is, even if any of these polymerizability and polymerization process is adopted, the present invention particularly limits the polymerization method and the polymerization process as long as the presence of a polymer having a mercapto group at the terminal in the polymerization system is achieved during the polymerization. Not something to do. Further, the addition amount and the addition method of the polymer having a mercapto group to the polymerization system are not particularly limited, and should be naturally defined from the physical property values of the target block copolymer.

The radical polymerization for obtaining the block copolymer of the present invention is carried out by a conventional radical polymerization initiator such as 2,2′-azobisisobutyronitrile, benzoyl peroxide,
It can be carried out by using lauroyl peroxide, diisopropyl peroxycarbonate, potassium persulfate and ammonium persulfate, but a polymer having a mercapto group at the terminal can be polymerized in an aqueous system like polyethylene glycol. In this case, it is also possible to start redox with a mercapto group at the end of the polymer and an oxidizing agent such as potassium bromate, potassium persulfate, ammonium persulfate, and hydrogen peroxide. Among them, potassium bromate does not generate a radical by itself under ordinary polymerization conditions, and decomposes only by a redox reaction with the mercapto group at the terminal of the employee to generate a radical. It is a particularly preferable initiator for synthesizing a polymer.

When radical polymerization is carried out in the presence of a polymer having a terminal mercapto group in the present invention, the polymerization system is preferably acidic. This is because the mercapto group is ionically added to and disappears from the double bond of the monomer under basic conditions, and if the polymerization is an aqueous system, all the polymerization operations are performed at pH 4
It is desirable to carry out the following.

The polymer constituting the other component of the block copolymer of the present invention is constituted by a homopolymer or a random copolymer of radically polymerizable monomers, and there is no particular limitation on the composition, molecular weight, molecular weight distribution and the like. Radical (co) polymerizable monomers include olefins such as ethylene, propylene and isobutylene, acrylic acid, methacrylic acid and their esters, methyl acrylate, ethyl acrylate,
Butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 2-hydroxyethyl acrylate,
Methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, 2-hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and their quaternary compounds, acrylamide, methacryl Amide, N-methylol acrylamide,
N, N-dimethylacrylamide, acrylamide-2-
Acrylamide-based monomers of methylpropanesulfonic acid and its sodium salt, styrene-based monomers such as styrene, α-methylstyrene, p-styrenesulfonic acid and its sodium and potassium salts, acrylonitrile, methacrylonitrile, N-vinylpyrrolidone, etc. can give.

The block copolymer obtained in the present invention has an extremely wide range of properties by selecting a polymer and a monomer having a mercapto group at the terminal, and by adjusting the composition and molecular weight of both component polymers. It has properties different from polymer blends, such as good compatibility between the polymer of one component of the block copolymer and the polymer of the other component. Agent,
It can be applied to a wide range of applications such as processing agents for resins, paper, fibers, etc.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. In the examples, parts and% mean weight basis.

Preparation of No. 1 (polyethylene glycol having a mercapto group at the end): Polyethylene glycol 4000 (average molecular weight 3000, made by NOF Corporation) 500 g was dissolved in 200 ml of methylene chloride and 80 g of pyridine, and 200 g of tosyl chloride was added to the mixture at 25 ° C
And reacted for 12 hours. After passing the salt, the solution was poured into a large excess of ether to precipitate the produced polyethylene glycol ditosylate, which was passed, thoroughly washed with ether and dried. Next, dissolve 500 g of this polyethylene glycol ditosylate in 300 ml of ethanol to obtain 50 g.
Of thiourea was added and the mixture was reacted under reflux for 96 hours. Subsequently, 27 g of sodium hydroxide and 300 g of distilled water were added under a nitrogen stream, and the mixture was reacted under reflux for 3 hours. After cooling to room temperature and neutralizing with 10% H ₂ SO ₄ aqueous solution to pH = 3 to 3.5, methylene chloride 1 was dissolved and extraction was carried out to obtain a methylene chloride solution of α, ω-dimercaptopolyoxyethylene. Obtained. Subsequently, this methylene chloride solution was put into ether to precipitate α,
ω-dimercaptopolyoxyethylene was reprecipitated and purified twice with a methanol-ether system. Obtained α, ω −
The SH group content of dimercaptopolyoxyethylene 4000 was 5.64 × 10 ⁻⁴ eq / g as a result of titration with I ₂ .

Preparation of No. 2 (polymethylmethacrylate having mercapto group at the end): Methylmethacrylate (hereinafter abbreviated as MMA) 2
90 parts and 4.6 parts of thioacetic acid were placed in a reaction vessel, and the inside was sufficiently replaced with nitrogen, then the external temperature was raised to 85 ° C., and 10 parts of MMA containing 0.3 part of 2,2′-azobisisobutyronitrile was added for polymerization. . The polymerization rate after 1.5 hours was 78.8%. After the polymerization, the mixture was diluted with acetone and poured into n-hexane to precipitate and precipitate the polymer, and reprecipitation purification was repeated three times with an acetone / water system to remove unreacted MMA.

Next, 200 g of this polymer was added to 320 g of acetone and 80 g of methanol.
12g of 10% NaOH solution in methanol
In addition, the mixture was reacted at 40 ° C for 2.5 hours. Then IN H ₂ SO ₄ 50m
It was put into 5 parts of water containing 1 and the precipitated polymer was separated, washed thoroughly with water and dried to obtain PMMA having a mercapto group at one end. This PMMA was [η] = 0.06 (dl / g) as measured by [η] in acetone at 30 ° C, and the amount of mercapto group was 9.99 × 10 ^-5 eq / g as a result of titration with iodine in an acetone-water system. It was.

Example 1 To 10 parts of the polymer of No. 1 was added 110 parts of distilled water and dissolved to obtain N / 2-
H ₂ SO ₄ was added to adjust the pH to 3, and 10 parts of N, N-dimethylacrylamide which had been previously nitrogen-substituted was added. Next, a total amount of an aqueous solution prepared by dissolving 0.94 part of potassium bromate in 10 parts of distilled water in which nitrogen was replaced was added, and polymerization was started at 30 ° C. Polymerization was completed in 2 hours, the polymerization rate was 100.1%, and the solid content concentration was 14.
A 4% aqueous polyethylene glycol (PEG) -poly (N, N-dimethylacrylamide) block copolymer solution was obtained.

Polyethylene glycol-poly (N, obtained in Example 1
10% of N-dimethylacrylamide) block copolymer
The aqueous solution was cast into a film. On the other hand, polyethylene glycol and poly (N,
Prepare a 10% aqueous solution of N-dimethylacrylamide),
It was cast into a film. The film from the block copolymer was transparent and uniform, but the film from the mixture became cloudy and phase separation was observed.

Example 2 To 10 parts of the polymer of No. 1 was added 110 parts of distilled water to dissolve, and N / 2-
H ₂ SO ₄ was added to adjust the pH to 3, and 10 parts of acrylamide was added to dissolve the acrylamide. After nitrogen substitution, the temperature was raised to 60 ° C. Then, the addition of an aqueous solution of 0.94 g of potassium bromate dissolved in nitrogen-substituted distilled water was started to start the polymerization. The addition of the potassium bromate aqueous solution was carried out uniformly at a rate of 2 ml / 5 minutes for 30 minutes. Polymerization is completed in 90 minutes, the polymerization rate is 99.3%,
An PEG-polyacrylamide block copolymer aqueous solution having a solid content concentration of 14.2% was obtained.

Example 3 Polymerization was carried out under the same conditions as in Example 2 except that the monomer (acrylamide) in Example 2 was changed to methyl acrylate. The polymerization was completed in 2.0 hours, and a dispersion liquid of a PEG-polymethyl acrylate block copolymer having a polymerization rate of 98.7% and a solid content concentration of 14.1% was obtained.

Example 4 PVA217 (polyvinyl alcohol: manufactured by Kuraray Co., Ltd. degree of polymerization
1700, saponification degree 88 mol%) 100 parts distilled water to 0.1 part,
It was melted at 0 ° C and cooled to 60 ° C under a stream of nitrogen. A styrene solution prepared by dissolving 50 parts of No. 2 polymer and 0.2 part of 2,2'-azobisisobutyronitrile in 100 parts of styrene was added to the solution after nitrogen substitution, and polymerization was carried out smoothly. Polymerization was carried out at 60 ° C. for 20 hours, and the polymerization rate was 98.2%. After termination of the polymerization, the polymer was washed with water, washed with water, and dried to obtain 145 g of a polymer containing a block copolymer of poly (methyl methacrylate) -polystyrene.

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Claims (2)

[Claims] 1. Radical polymerization of a radically polymerizable monomer (excluding vinyl ester) in the presence of a polymer having a mercapto group only at its terminal (excluding polyvinyl alcohol polymer and polyvinyl ester polymer). A process for producing a block copolymer, characterized by: 2. A process for producing a block copolymer according to claim 1, wherein radical polymerization is carried out under acidic conditions.