JPH03221532A - Preparation of shaped product - Google Patents

Abstract

PURPOSE:To inexpensively and highly safely prepare a shaped product having excellent heat resistance and durability by bringing a solution comprising a specific polyvinyl alcohol polymer into contact with an organic solvent- containing aqueous solution, etc. CONSTITUTION:A solution (room temperature - 250 deg.C) prepared by dissolving a polyvinyl alcohol polymer (preferably having a polymerization degree of 500-20000) in water, dimethyl sulfoxide, etc., in a concentration of 1-50wt.% is brought into contact with water or an aqueous solution containing < 50wt.% of an organic solvent capable of coagulating the polyvinyl alcohol polymer, followed by drying to provide the objective shaped product. The polyvinyl alcohol polymer is prepared by saponifying the homopolymer of preferably vinyl pivalate, etc., (preferably a saponification degree of 70-99.9mol%) and has a syndiotacticity of >=55%.

Description

DETAILED DESCRIPTION OF THE INVENTION 2. Industrial Fields of Application 2. The present invention relates to a process for producing molded articles made from polyvinyl alcohol polymers having higher non-diotactic properties.

Conventional technology: Conventional fibers or membranes made of alcohol-based polymers are formed using dry coagulation, wet coagulation,
It is molded by a dry-wet coagulation method or a gel coagulation method. These molding methods are appropriately selected depending on the use and purpose of the molded article, but wet coagulation methods, dry-wet coagulation methods, gel coagulation methods, and the like are preferably used because of their high productivity.

Conventional polyvinyl alcohol-based polymers are attack polymers, and contain about 53 mol% of amino acid protein. Therefore, when molding the polyvinyl alcohol polymer by a wet coagulation method or a dry-wet coagulation method, it may be necessary to extrude the polyvinyl alcohol polymer solution into an organic solvent, an aqueous inorganic salt solution, or an aqueous inorganic base solution. Ta. However, the method of using an organic solvent as a coagulating solvent is expensive and has the risk of fire. In addition, methods using inorganic salt aqueous solutions or inorganic base aqueous solutions have problems with operability, corrosion of equipment, and residual inorganic salts or inorganic bases, resulting in poor heat resistance, poor durability, and molded products. There were problems such as coloring.

E Problems to be Solved by the Invention] Under such circumstances, the present invention relates to a molded product of a polyvinyl alcohol polymer having a high non-geotufting property, which is low cost, highly safe, and has improved operability and corrosion of equipment. The aim is to provide a manufacturing method that is free from problems and provides molded products with good heat resistance and durability.

[Means for Solving the Problems] The present inventors have made extensive studies to solve the above problems, and as a result, the present inventors have determined that a solution layer consisting of non-geotuftin tea or a polyvinyl alcohol polymer containing 55 mol% or more of organic The present invention has been completed based on the discovery that a method for producing a molded article, which is characterized by contacting the molded article with water or aqueous solution having a solvent content of less than 50% by weight, achieves the above object.

The present invention will be explained in detail below.

In the polyvinyl alcohol-based polymer according to the present invention, the non-geotufted tea content is 55 mol% or more. Increasing the amount of non-geo-tufted tea is effective in improving the strength, water resistance and corrosion resistance of the molded product, and in order to achieve the effects of the present invention, the amount of non-geo-tufted tea should be 55 mol% or more. The content is preferably 57 mol% or more, more preferably 60 mol% or more.

This highly concentrated polyvinyl alcohol polymer cannot be obtained from saponification of polyvinyl acetate, which is a common method for producing polyvinyl alcohol. The polyvinyl alcohol-based polymers with high diotactic protein used in the present invention include vinyl esters with bulky side chains such as vinyl pivalate, vinyl trichloroacetate, vinyl trichloroacetate, and vinyl formate; It is obtained by saponification of high vinyl ester polymers or by decomposition of polyvinyl ethers such as t-butyl vinyl ether and trimethylnoryl vinyl ether. Among these, i! The vinyl pivalate homopolymer or f2 is preferably a polyvinyl alcohol polymer that is easily saponified and the obtained polyvinyl alcohol polymer has good water resistance. Here, the comonomer units in the case of a copolymer are divided into units that generate vinyl alcohol units by saponification and other units. The former comonomer units are copolymerized for the purpose of controlling tactinotes, and include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate,
These are vinyl esters such as vinyl pivalate, vinyl persate, vinyl laurate, vinyl stearate, vinyl benzoate, etc., and the copolymerization composition thereof is determined in relation to the amount of synthonotactic acid. On the other hand, the latter comonomer unit is copolymerized primarily for the purpose of modification, and is used within the scope of the invention. Examples of such units include olefins such as ethylene, propyleno, ■-butene, and isobutyne, acrylic acid and its salts, methyl acrylate, ethyl acrylate, n-propyl acrylate, and 1-propyl acrylate. ,
Acrylic acid lobe chain, 1-butyl acrylate, t-butyl acrylate, 2-ethylhexynol acrylate,
Acrylic acid esters such as dodenyl acrylate and octadenol acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate, n-methacrylate
propyl, i-propyl methacrylate, n methacrylate
-butyl, i-butyl methacrylate, t- methacrylate
Butyl, methacrylic acid esters such as 2-ethylhexynyl methacrylate, dodenyl methacrylate, and octadenyl methacrylate, acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-trimethylacrylamide, diacetone acrylamide, acrylamide propanesulfonic acid and its salts, acrylamide propyldimethylamine and its salts, its quaternary salts, acrylamide derivatives such as N-methylolacrylamide and its derivatives, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamide propane Sulfonic acid and its salts, methacrylamide probylne methylamine and its salts or quaternary salts, methacrylamide derivatives such as N-methylolacrylamide and its derivatives, methyl vinyl ether, ethyl vinyl ether, n-propylene vinyl ether, i-propyl Vinyl ethers, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodenor vinyl ether, vinyl ethers such as stearyl vinyl ether, nitriles such as acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, vinyl fluoride, Vinyl halides such as vinylidene chloride, allyl compounds such as allyl acetate and allyl chloride, maleic acid and its salts or esters,
Itaconic acid and its salts and esters, vinylnoryl compounds such as vinyltrimethoxysilane, isopropenyl acetate, and the like.

The degree of saponification of the polyvinyl alcohol polymer in the present invention is not particularly limited, and is generally within the range of degrees of saponification. 10-99.
Selected from 99 mol%. In particular, when heat resistance, water resistance, and oil resistance are required for molded products, the degree of saponification is 70~
9999 mol% is preferred. Here, the degree of saponification represents the ratio of vinyl alcohol units after saponification to units that can be converted into vinyl alcohol units by saponification in the polyvinyl alcohol polymer.

The degree of polymerization of the polyvinyl alcohol polymer used in the present invention is not particularly limited, and may be selected depending on the purpose of the molded product, but from the viewpoint of processing characteristics, it is between 500 and 20.
0000 is preferred.

Here, the degree of polymerization is the intrinsic viscosity (3Ω) of anibolyvinyl acetate in acetone obtained by acetylating the polyvinyl alcohol polymer.
It is expressed as the viscosity average degree of polymerization obtained from ℃ measurement), and is a value calculated using the following formula.

P= (Eη 3 to 1000/7.94) ”'
The solvent constituting the solution of the polyvinyl alcohol polymer in the present invention is not particularly limited as long as it dissolves the polyvinyl alcohol polymer and easily mixes with the water of the coagulation liquid, such as dimethyl sulfoxide. , trimethylformamide, trimethylacetamide, ethylene glycol, glycerin, water, hexafluoroisopropanol, etc. are used alone or in combination.Aqueous solutions of inorganic salts such as lithium chloride and carnoum chloride are also used alone or in combination with the above-mentioned organic solvents. Among these, water, dimethyl sulfoxide, a mixture of dimethyl sulfoxide and water, glycerin, ethylene glycol, etc. are preferably used. The concentration varies depending on the film forming method, but it is usually 1~
50% by weight, and the temperature of the solution is usually between room temperature and 25% by weight.
It is in the range of 0°C.

The method for producing a molded article of the present invention includes coagulation, extraction, etc., by contacting a solution made of the polyvinyl alcohol polymer described above with an aqueous solution containing less than 50% by weight of an organic solvent or a coagulation liquid made of water. Special feature 1:
g. Contact between the solution and the coagulation liquid is accomplished by one or more coagulation baths or extraction baths.

The present invention 1 coagulation liquid is water ah
Preferably, an aqueous solution consisting of water and an organic solvent capable of coagulating the polyvinyl alcohol polymer is used. The aqueous solution may contain less than 50% by weight of an organic solvent, and the content can be determined as appropriate for each coagulation bath or extraction bath. In the case of wet coagulation methods such as wet spinning and wet film forming methods, dry-wet coagulation methods such as wet-dry spinning methods and wet-dry film forming methods, polyvinyl alcohol polymers are coagulated by solvent extraction from a solution. To achieve this quickly, the content of organic solvent in the coagulation layer is 30
Preferably less than 10% by weight, more preferably less than 10% by weight. In addition, in the case of gel coagulation methods such as gel spinning method or gel film forming method, spinning or film forming can be achieved by gelation, and it is necessary to quickly achieve coagulation by solvent extraction from a solution consisting of polyvinyl alcohol polymer. Second, the content of solvent in water is preferably less than 50% by weight, more preferably less than 30% by weight.

That is, the coagulation bath in the present invention is preferably water alone or has a lower organic solvent content.

Further, in the production method of the present invention, inorganic salts or inorganic bases are not required in the coagulation liquid, and from the viewpoint of heat resistance and coloring of the molded product, it is preferable not to contain inorganic salts or inorganic bases.

The temperature of the coagulating liquid used in the method for producing a molded product of the present invention is not particularly limited and is appropriately selected depending on the intended use of the molded product to be obtained, but is usually selected from within the boiling point range from room temperature to normal pressure. However, in the wet coagulation method, the coagulation rate is controlled by solvent extraction from a solution of polyvinyl alcohol polymer in the dry-wet coagulation method, and in the case of the gel coagulation method, the gelation rate is controlled. For control, it is also possible to select a temperature range from the melting point of water to room temperature, or a temperature range above the boiling point at normal pressure when using a pressure vessel.

There is no particular restriction on the shape of the molded product obtained by the molding method of the present invention. Examples include fibers, membranes, and nets obtained by membrane methods, etc.;
It can also be applied to ultra-thin films.

The molded product of the polyvinyl alcohol polymer of the present invention may contain anything other than the polyvinyl alcohol polymer described above, as long as it does not deviate from the spirit of the present invention. and other polymers, plasticizers such as glycerin, clay, glue, and inorganic compounds such as carnoum carbonate.

Further, dyes and pigments for coloring, stabilizers such as antioxidants and ultraviolet absorbers may be added as necessary.

[Examples] Hereinafter, the present invention will be specifically explained using examples, but the present invention is not limited to the examples.

t. In the example, ``The police officer shall be responsible for the police unless otherwise noted.''
Parts by weight.

Synthesis Example 600 parts of vinyl pivalate monomer and 200 parts of methanol were placed in a reaction vessel equipped with a stirrer, and the system was purged with nitrogen using nitrogen gas public. Separately methanol 26W
A solution was prepared by dissolving 0.0712 parts of 2,2'-azobisisobutyronitrile as an initiator in J, and the solution was purged with nitrogen by bubbling with nitrogen gas. The temperature of the reaction vessel was raised, and when the internal temperature reached 60°C, a butanol solution containing an initiator was injected to start polymerization. After 190 minutes, when the polymerization rate reached 50%, the polymerization was stopped by cooling.
While occasionally adding t-butanol, unreacted vinyl pivalate monomer was removed under reduced pressure to obtain a solution of polyvinyl pivalate in t-butanol. Subsequently, t-butanol was removed under reduced pressure to obtain 40.2 wt % of polyvinyl pivalate dissolved in tetrahydrofuran.

Next, add this solution 2 to a reactor equipped with a stirrer and a reduction cooling tube.
Weigh out 49 parts, heat it to 60°C, replace the nitrogen scum with a stream of nitrogen, hold it at 60°C, cool it, prepare it separately, replace it with nitrogen, and make 21 parts of a 25% methanol solution of potassium hydroxide. was added and stirred thoroughly. The system gelled in about 20 minutes, or after another 100 minutes at 60'C, 68 parts of acetic acid was added along with 20 parts of methanol to neutralize the potassium hydroxide and form a gel. After pulverization, Soxhlet cleaning with methanol was performed to obtain polyvinyl alcohol. After adding 10 parts of acetic anhydride and 2 parts of pyridine to 0.5 parts of the obtained polyvinyl alcohol and sealing the tube, 12 parts of polyvinyl alcohol was added.
Acetylation was achieved by heating at 0°C for 8 hours. The obtained polyvinyl acetate was precipitated in n-hexane and purified by repeating reprecipitation twice in an acetone-n-hexane system. The obtained polyvinyl alcohol was dissolved in d,-DMSO and NMR measurement revealed that the degree of saponification was 99.6 mol% and the non-geotoughness was -61,ffi. The viscosity average degree of polymerization determined from [η] measured at 30°C was 1720.

Example 1 A solution of 5 parts of the polyvinyl alcohol obtained in the synthesis example dissolved in 5 parts of 7-methyl sulfoquinone at 80° C. was deposited on a polyethylene terephthalate film to a thickness of 1.5 mm. Cast with a bar coater using a 0mm spacer, immerse in a sufficient amount of distilled water at room temperature, solidify for about 30 minutes, and then
A polyvinyl alcohol film was obtained by drying in hot air at C for about 60 minutes.

This film showed no change in coloring or the like even after being left in a 90°C dry oven for 100 hours, and had good heat resistance and durability.

Comparative Example 1 A polyvinyl alcohol membrane was obtained in the same manner as in Example 1, except that a coagulating solution consisting of 300 parts of sodium sulfate and 700 parts of water was used instead of distilled water.

This film turned brown after being left in a 90°C dry oven for 100 hours, and its heat resistance and durability were poor.

Comparative Example 2 Saponification degree of 999 mol% obtained by saponifying polyvinyl acetate
When film formation was attempted in the same manner as in Example 1 using polyvinyl alcohol having a non-notacticity of 52.8 mol% and a degree of polymerization of reacetate of 1700, the polyvinyl alcohol did not coagulate and remained dissolved. Ta.

[Effects of the Invention] As is clear from the above examples, the method for producing a molded article of a polyvinyl alcohol polymer of the present invention can only be achieved by using a polyvinyl alcohol polymer with a non-toxicity content of 55 mol% or more. It is what was done. This method for producing molded products can be applied not only to fibers and membranes but also to the production of molded products of all shapes, and compared to conventional production methods, it not only provides molded products with better heat resistance and durability. Since water is used as the coagulating liquid, it has extremely high industrial value, as it can reduce process costs and improve safety.

Claims (2)

[Claims] (1) A polyvinyl alcohol polymer characterized in that a solution consisting of a polyvinyl alcohol polymer having a syndiotacticity of 55 mol% or more is brought into contact with an aqueous solution or water having an organic solvent content of less than 50% by weight. A method for producing a molded article consisting of: (2) The method for producing a molded article according to claim 1, wherein the polyvinyl alcohol polymer contains vinyl pivalate units.