JPH0739452B2 - Method for producing block copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a block copolymer containing a polyvinyl ester polymer as a component and a method for producing a block copolymer containing a polyvinyl alcohol polymer as a component. More specifically, polyvinyl characterized by polymerizing vinyl ester such as vinyl acetate in the presence of a polymer having a mercapto group only at one end or at both ends (excluding polyvinyl alcohol polymer and polyvinyl ester polymer). TECHNICAL FIELD The present invention relates to a block copolymer having an ester polymer as a component and a method for producing a block copolymer having a PVA polymer as a component by saponifying the block copolymer.

Block copolymers consisting of bonds of polymer components with different properties have various different physical properties corresponding to the variety of combinations of copolymer components, and are used as impact-resistant resins, polymeric emulsifiers, dispersants, etc. In addition to its use, it has recently attracted attention as a membrane material and a medical material, and its research examples are extensive with the graft copolymer.

Regarding polyvinyl alcohol-based polymers (hereinafter abbreviated as PVA-based polymers), many studies and applications have been conducted on graft copolymers based on PVA-based polymers.
There are almost no examples of block copolymers containing an A-based polymer as one component. However, as is well known, PVA-based polymers are crystalline polymers that are rare among water-soluble polymers, and are widely used as water-soluble polymers with excellent mechanical and interfacial chemical properties. A block copolymer having a coalesced as one component is expected as a material having new properties while retaining the excellent properties of a PVA polymer.

As a result of diligent studies on the method for producing a block copolymer having a PVA polymer as one component, the present inventors have found that only one end or both ends (in the following description, “one end” means “only one end”). And “both ends” mean “both ends only”) having a mercapto group-containing polymer (excluding polyvinyl alcohol-based polymers and polyvinyl ester-based polymers; the same applies in the following description). Radical polymerization of vinyl ester such as vinyl acetate in the presence of
A block copolymer containing the obtained polyvinyl ester polymer as a component can be obtained, and by further saponifying it, a block copolymer containing a PVA polymer as a component can be easily produced. Heading, completes the present invention.

In the present invention, a vinyl ester such as vinyl acetate has a remarkably large chain transfer constant to a mercapto group, and therefore it is considered that a block copolymer can be easily obtained.

The polymer having a mercapto group at one end or both ends used in the present invention is a component that binds to the polyvinyl ester-based polymer and the PVA-based polymer of the present block copolymer, and its chemical and physical properties. Properties are a major factor in determining the physical properties of block copolymers. That is, in the method for producing a block copolymer having a polyvinyl ester polymer or a PVA polymer as a component of the present invention, when a vinyl ester such as vinyl acetate is polymerized, it has a mercapto group at one end or both ends to be present. It is also a major feature of the present invention that a block copolymer containing a PVA polymer having various different physical properties as one component can be easily produced by appropriately selecting the composition and the degree of polymerization of the polymer.

The weight ratio and the degree of polymerization of each component of the block copolymer obtained in the present invention are not particularly limited, but the weight ratio of each component is preferably (PVAc weight) / (polymer weight having a mercapto group at the terminal). = 0.1 to 500, more preferably 1 to 200
The degree of polymerization of the PVAc portion is preferably 50 to 3000.

The polymer having a mercapto group at one end or both ends can be obtained by the following method. The first method is to convert a polymer having a hydroxyl group at one end or both ends into a mercapto group by a chemical reaction, for example, after changing the hydroxyl groups at both ends of polyethylene glycol or polypropylene glycol to halide or sulfonate, An example is a method in which urea is added to give an isothiuronium salt, which is then 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 a method in which a monomer capable of radical polymerization is radically polymerized in the presence of thioacid, and the resulting polymer is treated with an alkali or an acid to introduce a mercapto group at one end of the molecule. For example, radical polymerization of methyl methacrylate (MMA), styrene, etc. in the presence of thioacetic acid, followed by alkali treatment can synthesize poly MMA or polystyrene having a mercapto group at one end.

The polymerization of vinyl ester such as vinyl acetate to obtain the block copolymer of the present invention is carried out by conventional radical polymerization initiators such as 2,2'-azobisisobutyronitrile, lauroyl peroxide, benzoyl peroxide and diisoproper. It is usually preferable to use oxycarbonate at 30 to 90 ° C. As the polymerization method for obtaining the block copolymer of the present invention, any polymerization method of bulk polymerization, solution polymerization and pearl polymerization can be adopted, but industrially, solution polymerization using ethanol as a solvent is followed by saponification. This is the most advantageous method when considering the process. The polymerization process can be carried out by a batch method, a semi-batch method, or a continuous method. That is, when any of these polymerization methods and polymerization processes is adopted, when polymerizing a vinyl ester such as vinyl acetate, if the presence of a polymer having a mercapto group at one end or both ends in the polymerization system is achieved. The present invention does not particularly regulate the polymerization method or the polymerization process. Further, the amount of the polymer having a mercapto group at one end or both ends at the time of polymerization to the polymerization system, the addition method is not particularly limited, and from the physical property value of the target block copolymer, it should be specified naturally. is there.

Examples of the vinyl ester used in the present invention include vinyl acetate, vinyl formate, vinyl propionate and vinyl benzoate, and vinyl acetate is preferably used. It is also possible to use a small amount of monomers copolymerizable with these vinyl esters, and examples of such monomers include ethylene, propylene, isobutylene, acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, acrylamide, methacrylamide, and ethyl vinyl ether. , Butyl vinyl ether, N-vinyl prolidone and the like.

The polyvinyl ester portion is saponified by saponifying a block copolymer containing the polyvinyl ester polymer thus obtained as a component by a conventional method, and a PV
A block copolymer containing the A-based polymer as a component can be obtained. The saponification reaction can be carried out by a method known as a general saponification method for polyvinyl ester polymers, that is, a method of heating at room temperature to 60 ° C in the presence of an alkali or acid catalyst, and subjecting it to alcoholysis or hydrolysis. , Sodium hydroxide in alcohol such as methal,
Alcohol decomposition with an alkali catalyst such as potassium hydroxide or sodium methylate is preferable because of its high saponification rate. The saponification degree of the polyvinyl ester portion can be variously changed by adjusting the reaction conditions such as the amount of catalyst, the saponification reaction temperature and the time. For example, the saponification degree is 50 to 100 mol%.
Can be After the saponification reaction is completed, the polymer is pulverized and then purified with a nonsolvent of the polymer to wash the alkali catalyst and by-produced alkali salt of acetic acid, etc., and then dried to obtain a PVA block copolymer with high whiteness. It is preferable because it is possible.

The polyvinyl ester-based polymer obtained in the present invention or
The block copolymer having one component of the PVA polymer is a composition of a polymer having a mercapto group at the terminal as described above,
It is possible to change variously depending on the molecular weight, the molecular weight of the polyvinyl ester polymer or the PVA polymer, and the weight fraction, and the properties different from those of the polymer blend, for example, one component of the block copolymer. Since it has properties such as good compatibility between the polymer of (1) and the polymer of the other component, it can be applied to various uses. For example, paper internal sizing agent, paper surface sizing agent, paper coating agent, fiber product sizing agent, warp sizing agent, fiber processing agent,
Coating materials such as paints, glass fiber coating agents, metal surface coating agents, anti-fogging agents, adhesives for wood, paper, aluminum foil, plastics, non-woven binders, fibrous binders, gypsum boards, fibreboards, etc. Binders for building materials, thickening agents for various emulsion adhesives, additives for urea resin adhesives, inorganic binders or additives for cement, mortar or ceramics, hot melt adhesives, pressure sensitive adhesives, etc. Agent-related, ethylene, styrene, vinyl acetate, (meth) acrylic acid ester, vinyl chloride, vinylidene chloride, dispersants for emulsion polymerization of ethylenically unsaturated monomers such as acrylonitrile and butadiene monomers, paints, adhesion Dispersion stabilizers such as agents, vinyl chloride, vinylidene chloride, styrene, (meth)
Acrylic ester, dispersion stabilizer for suspension polymerization of various ethylenically unsaturated monomers such as vinyl acetate, fiber, film,
Sheets, pipes, tubes, water-soluble fibers, molded films such as temporary coatings, hydrophilicity-imparting agents for hydrophobic resins, composite fibers,
It can be applied to a wide range of applications such as film-related additives for synthetic resins such as additives for molded products, soil improvement agents, soil stabilizers, and photosensitive resin applications.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. In addition, the middle part and% of an example mean a basis of weight.

Example 1 [Synthesis of polyethylene glycol having a mercapto group at the end] 500 g of polyethylene glycol 4000 (average molecular weight 3000, manufactured by NOF Corporation) was dissolved in 200 ml of methylene chloride and 80 g of pyridine, and 200 g of tosyl chloride was added, and the mixture was added at 25 ° C. The reaction was carried out for 12 hours. After passing the salt, the filtrate was poured into a large excess of ether to precipitate with the produced polyethylene glycol ditosylar, which was then thoroughly washed with ether and dried. Next, 500 g of this polyethylene glycol ditosylate was dissolved in 300 ml of ethanol, 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 flow, 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, extraction was carried out with methylene chloride 1 to obtain a methylene chloride solution of α, ω-dimercaptopolyoxyethylene. Obtained. Subsequently, this methylene chloride solution was poured into ether, and the precipitated α, ω-dimercaptopolyoxyethylene was purified twice by reprecipitation with a methanol-ether system. The amount of SH groups of the obtained α, ω-dimercaptopolyoxyethylene 4000 was 5.64 × 10 ⁻⁴ eq / g as a result of titration with I ₂ .

[Synthesis of Polyvinyl Acetate-Polyoxyethylene Block Copolymer and Polyvinyl Alcohol-Polyoxyethylene Block Copolymer]

Vinyl acetate (hereinafter abbreviated as VAc) 960 parts, methanol 220 parts and α, ω-dimercaptopolyoxyethylene 4000
After taking 4.20 parts in a reaction vessel and thoroughly replacing the inside with nitrogen, the external temperature was raised to 65 ° C and the internal temperature reached 60 ° C.
20 parts of methanol containing 0.694 parts of 2,2'-azobisisobutyronitrile were added. Immediately, 90 parts of a methanol solution containing 49.9 parts of α, ω-dimercaptopolyoxyethylene 4000 was added uniformly over 4.5 hours. The polymerization rate for 4.5 hours is
It was 50.6%. After 4.5 hours, the container was cooled, and VAC remaining under reduced pressure was expelled out of the system together with methanol while adding methanol to obtain a methanol solution of a polyvinyl acetate-polyoxyethylene block copolymer. (Concentration 43.2%) Add to this methanol solution at 40 ° C [Na
Saponification was carried out by adding a methanol solution of NaOH so that OH] / [VAc] = 0.05 (molar ratio) and allowing the mixture to stand at the same temperature for 30 minutes. The obtained block copolymer of polyvinyl alcohol and polyoxyethylene was thoroughly washed with methanol, purified and dried to obtain a white powdery polymer. The intrinsic viscosity of polyvinyl acetate-polyoxyethylene block copolymer in acetone measured at 30 ° C was 0.52dl.
It was / g. ([Η] = ηsp / c (1 + 0.
275Itasp) The polyvinyl alcohol obtained Te cowpea saponification - weight fraction of the polyoxyethylene of the polyoxyethylene Bro poke copolymer is measured by H-NMR (in d _6-DMSO) result is 11.2%, Saponification degree of PVA part is 9
It was 9.0% mol%.

Examples 2 to 4 Using the α, ω-dimercaptopolyoxyethylene 4000 obtained in Example 1, polyvinyl acetate-polyoxyethylene and polyvinyl alcohol having different polyoxyethylene 4000 contents were prepared in the same manner as in Example 1. A block copolymer of polyoxyethylene was obtained. The polymerization conditions, the polymerization results, and the properties of the resulting block copolymer are summarized in Table 1.

A 10% aqueous solution of the polyvinyl alcohol-polyethylene glycol block copolymer obtained in Example 4 was cast into a film. On the other hand, polyvinyl alcohol and polyethylene glycol of the same composition as this block copolymer
% Aqueous solution was prepared and 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 5 Polyethylene glycol 60 in the same manner as in Example 1
Α, ω-dimercaptopolyoxyethylene 6000 was obtained from 00 (average molecular weight: 8,500 Wako Yakuhin). The amount of SH group was 1.67 × 10 ⁻⁴ eq / g as a result of titration with I ₂ . Polymerization was carried out in the same manner as in Example 1 using this α, ω-dimercaptopolyoxyethylene 6000 to obtain a polyvinyl acetate-polyoxyethylene block copolymer and a polyvinyl alcohol-polyoxyethylene block copolymer. Got The polymerization conditions, the polymerization results, and the properties of the resulting block copolymer are summarized in Table 2.

A 10% aqueous solution of the polyvinyl alcohol and polyethylene glycol block copolymer obtained in Example 5 was cast into a film. On the other hand, polyvinyl alcohol and polyethylene glycol of the same composition as this block copolymer
% Aqueous solution was prepared and 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.

Examples 6 to 7 [Synthesis of polypropylene glycol having mercapto group at terminal] 200 g of polypropylene glycol 2000 (average molecular weight 2000, manufactured by Sanyo Kasei) was dissolved in 200 ml of pyridine, 77 g of tosyl chloride was added, and the mixture was added at 25 ° C. for 24 hours. It was made to react. After passing the salt, the solution was poured into a large amount of distilled water, the produced polypropylene glycol ditosylate was separated, thoroughly washed with distilled water, and then dried. Next, 200 g of this polypropylene glycol ditosylate was dissolved in 300 ml of ethanol, 30 g of thiourea was added, and the mixture was reacted under reflux for 120 hours. Then, under a nitrogen flow, 17 g of sodium hydroxide and 100 of distilled water.
g was added and the mixture was reacted under reflux for 3 hours. Cool to room temperature, 1
After neutralizing with 0% H ₂ SO ₄ aqueous solution to adjust pH to 3 to 3.5, extraction was carried out with methylene chloride 1 to obtain a methylene chloride solution of α, ω-dimercaptopolyoxypropylene. The methylene chloride solution was thoroughly washed with water, dehydrated with Na ₂ SO ₄ , and then methylene chloride was removed under reduced pressure to obtain α, ω-dimercaptopolyoxypropylene. Obtained α, ω −
The SH group content of dimercaptopolyoxypropylene 2000 was 4.80 × 10 ⁻⁴ eq / g as a result of titration with I ₂ .

[Synthesis of block copolymer]

This α, ω-dimercaptopolyoxypropylene 2000 was used in the same manner as in Example 1 to obtain a polyvinyl acetate-polyoxypropylene block copolymer and a polyvinyl alcohol-polyoxypropylene block copolymer. It was The polymerization conditions, the polymerization results, and the properties of the resulting block copolymer are summarized in Table 3.

Examples 8 to 9 [Synthesis of polymethylmethacrylate having a mercapto group at one end] Methyl methacrylate (hereinafter abbreviated as MMA) 290 parts, thioacetic acid
After 4.6 parts was placed in a reaction vessel and the inside was sufficiently replaced with nitrogen, the external temperature was raised to 85 ° C., and 10 parts of MMA containing 0.3 part of 2,2′-azobisisobutyronitrile was added to perform polymerization. The polymerization rate after 1.5 hours was 78.8%. After polymerization, the mixture was diluted with acetone and poured into n-hexane to precipitate and precipitate the polymer, and the unreacted MMA was removed by repeating reprecipitation and purification three times with an acetone / water system.

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 1 N H ₂ SO ₄ 50
The polymer was poured into 5 ml of water containing ml, and the precipitated polymer was separated, washed thoroughly with water and dried to obtain PMMA having a mercapto group at one end. This PMMA is [η] = 0.06 (dl / g) from [η] measurement at 30 ° C in acetone, and the amount of mercapto group is the result of titration with iodine in an acetone-water system.
It was 9.99 × 10 ^-5 eq / g.

[Synthesis of Polyvinyl Acetate-Polymethyl Methacrylate Block Copolymer and Polyvinyl Alcohol-Polymethyl Methacrylate Block Copolymer]

A block copolymer was obtained in the same manner as in (Example 1) using polymethylmethacrylate having a mercapto group at one end. However, α-mercapto PMMA added continuously is
It was added by dissolving in methyl acetate instead of methanol.
The polymerization conditions, the polymerization results, and the properties of the resulting block copolymer are summarized in Table 4.

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Claims (2)

[Claims] 1. A polyvinyl ester polymer characterized by polymerizing a vinyl ester in the presence of a polymer having a mercapto group only at its terminal (excluding a polyvinyl alcohol polymer and a polyvinyl ester polymer). A method for producing a block copolymer as a component. 2. A polyvinyl alcohol-based polymer, characterized in that a vinyl ester is polymerized in the presence of a polymer having a mercapto group only at its terminal (excluding a polyvinyl alcohol-based polymer and a polyvinyl ester-based polymer) and further saponified. A method for producing a block copolymer containing a polymer as a component.