JP3509026B2 - Method for producing polyvinyl alcohol-based resin molded product - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound containing an oxyalkylene group.
By limiting the amount , viscosity and methanol-soluble content, polyvinyl alcohol having good thermal stability (hereinafter simply referred to as PV
A) (Abbreviated as A) -based resin to produce high quality molded products,
In particular, the present invention relates to a method for producing a film having little fish eyes and coloring. [0002] Conventionally, PVA resins, especially PVA resins having a high degree of saponification, have a high softening point and are close to the thermal decomposition temperature. Therefore, PVA resins can be used alone without a plasticizer. When a film or the like is produced by melt molding, it is extremely difficult to obtain a practical molded product because the melt viscosity is high, and degradation and coloring due to decomposition are severe. Therefore, it is essential to lower the softening temperature by blending a plasticizer such as glycerin. However, in order to achieve the required melting temperature and melt viscosity under ordinary molding conditions, it is essential to add a considerably large amount of the plasticizer, and the resulting molded product absorbs moisture at high temperature and high humidity. Since the adhesiveness of the surface of the molded article is increased, the molded articles are easily blocked by each other, and the plasticizer bleeds to the surface. [0003] In order to obtain a plastic-free molded product, the viscosity of a PVA resin must be 10 centipoise (2 centipoise).
(At 0 ° C., 4% by weight)
If it is not 0 mol% or less, it is difficult to perform melt molding, but in this case, crystallinity is reduced, swelling with water is increased, and water resistance is also lacking. Further, the film is brittle even during drying, and has a drawback in film strength. In addition, the gas barrier properties are very poor, leaving many issues to be improved, such as easily causing a blocking phenomenon,
It is hardly used for practical moldings. On the other hand, if the PVA resin has a viscosity of 10 centipoise (at 20 ° C., 4% by weight) or less, it can be melt-molded even in a high saponification degree (80 mol% or more) region, and the above-mentioned disadvantages occur. Although it is useful for molding without being used, it is extremely colored and easily deteriorated by heat during melt molding. In addition, the viscosity stability is not always sufficient, such as the tendency for thickening to occur not only at the time of melt molding but also at the time of molding processing. Therefore, it is not always sufficient in terms of viscosity stability. Roughness such as a line pattern tends to occur, and there is a problem that strict control of melt molding conditions is required to obtain a uniform product. [0005] The occurrence of such fish eyes remarkably impairs the appearance of the product and may lower the film strength around the fish eyes. Further, when the film is extruded and formed, a resin is adhered on the machine to generate a dust. Such dust causes adverse effects such as causing foreign matter and kogation in the molded product, or having to interrupt the work due to the breakage of the molded product, and adversely affects the quality of the film as well as the fish eye. Therefore, a process for producing a PVA-based resin molded product which can be easily melt-molded with a plasticizer-free system and has a very excellent quality of the obtained molded product is extremely industrially advantageous. The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that an oxyalkylene group obtained by saponifying an oxyalkylene group-containing vinyl ester polymer with an alkali catalyst. Polyvinyl alcohol-based resin, wherein the oxyalkylene of the PVA-based resin
The present inventors have found that such disadvantages can be solved by limiting the group content, the aqueous solution viscosity and the methanol-soluble content, and completed the present invention. That is, the present invention relates to "1. An oxyalkylene group-containing polyvinyl alcohol obtained by saponifying an oxyalkylene group-containing vinyl ester polymer with an alkali catalyst.
A coal-based resin having an oxyalkylene group content of
5 to 40% by weight based on the whole resin, and 20 ° C
Is 4 wt% aqueous solution viscosity of the preparation of the PVA-based resin molded product, which comprises melt-molding a 10 centipoise and oxyalkylene group-containing polyvinyl alcohol resin methanol soluble component is 5 wt% or less "in . [0008] The present invention relates to a method for melting and molding a non-plastic system.
Even when a PVA-based resin having a high degree of saponification of 0 mol% or more is used, the thermal stability of the PVA-based resin is improved by limiting the content of the oxyalkylene group, the viscosity of the aqueous solution, and the methanol-soluble component, It is characterized in that coloring and fisheye hardly occur and generation of rust is prevented, and a high-quality PVA-type resin molded product is always obtained. Hereinafter, the present invention will be described in detail. The PVA resin used in the present invention is obtained by saponifying polyvinyl acetate. Further, a monomer copolymerizable with vinyl acetate as a main component, for example, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid or salts thereof, and mono- or dialkyl esters Acrylonitrile, nitriles such as methacrylonitrile, acrylamide, amides such as methacrylamide, ethylenesulfonic acid, allylsulfonic acid, olefinsulfonic acid such as methallylsulfonic acid or a salt thereof, ethylene, propylene, isobutylene, α- Copolymers using olefins such as octene, α-dodecene, α-octadecene, alkyl vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride, oxyalkylenes, etc. Resin Murrell. [0010] Among such PVA resins , it is necessary to use an oxyalkylene group-containing PVA (hereinafter abbreviated as EO-PVA) resin modified with oxyalkylenes.
Now , such an EO-PVA-based resin will be described in detail. The oxyalkylene group is represented by the general formula 1,
[However, R ¹ and R ² are hydrogen or an alkyl group; X is hydrogen;
An organic residue such as a kill group, an alkyl ester group, an alkyl amide group, or a sulfonate group, and n represents an integer of 1 to 300]. X is usually hydrogen. The number of n is preferably an oxyalkylene group of about 2 to 300, particularly preferably about 5 to 300 , and a polyoxyethylene, polyoxypropylene group, polyoxybutylene group or the like is effective. ## STR1 ## The PVA resin having an oxyalkylene group can be produced by any method. For example, a method of polymerizing a vinyl ester in the presence of polyoxyalkylene and saponifying, a method of copolymerizing an unsaturated monomer having an oxyalkylene group with a vinyl ester, and a method of saponifying, etc. Practical in terms of manufacturing and performance. The following method will be specifically described. Examples of the unsaturated monomer having an oxyalkylene group include the following. However, the present invention is not limited to only these. (Meth) acrylic acid ester type represented by the general formula 2 [where R is hydrogen or a methyl group, A
Is an alkylene group, a substituted alkylene group, a phenylene group, a substituted phenylene group, m is an integer of 0 or 1 or more, and n is 1 to 1.
00 integer], such as polyoxyethylene (meth) acrylate and polyoxypropylene (meth) acrylate. Embedded image (Meth) acrylic acid amide type represented by the general formula 3 [where R ³ is hydrogen or an alkyl group or a chemical formula 4, A, R, R ¹ , R ² , m and n are the same as those described above] , Polyoxyethylene (meth) acrylamide,
Polyoxypropylene (meth) acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1)
-Dimethylpropyl) ester and the like. Embedded image Embedded image (Meth) allyl alcohol type [R, R ¹ , R ² , n are the same as those described above] represented by the general formula ( 5): polyoxyethylene (meth) allyl ether, polyoxypropylene (meth) allyl ether And the like. Embedded image Vinyl ether type [A, R ¹ , R ² , m and n are the same as those described above] represented by the general formula 6 and include polyoxypropylene vinyl ether and the like. Among these monomers, the (meth) alcohol type is preferably used. As vinyl esters,
Vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl palmitate, vinyl stearate and the like are used alone or in combination, but in practice Vinyl acetate is preferred. Embedded image In the present invention, at the time of such polymerization, the unsaturated monomer having an oxyalkylene group as described above, and other general monomers other than vinyl ester are present in a small amount as long as the water solubility is not impaired. May be. These monomers are exemplified below. Ethylenically unsaturated carboxylic acid alkyls
Ether such as crotonic acid methyl, ethyl crotonate, methyl itaconate, ethyl itaconate, methyl sorbate, ethyl sorbate, maleic acid monoalkyl esters, dialkyl maleates, the alkyl esters of oleic acid,
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, ( Meta)
Decyl acrylate, hexadecyl (meth) acrylate,
Octadecyl (meth) acrylate and the like can be mentioned. Allyl esters of saturated carboxylic acids Allyl stearate, allyl laurate, allyl coconut oil, allyl octylate, allyl butyrate and the like. Α-olefin ethylene, propylene, α-hexene, α-octene,
α-decene, α-dodecene, α-hexadecene, α-octadecene and the like. Ethylenically unsaturated carboxylic acids (meth) acrylic acid, crotonic acid, (anhydride) maleic acid, fumaric acid, itaconic acid, and alkali metal salts and ammonium salts thereof. Alkyl vinyl ether propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, tetradecyl vinyl ether, hexadecyl vinyl ether, octadecyl vinyl ether and the like. Alkyl allyl ether Propyl allyl ether, butyl allyl ether, hexyl allyl ether, octyl allyl ether, decyl allyl ether, dodecyl allyl ether, tetradecyl allyl ether, hexadecyl allyl ether, octadecyl allyl ether and the like. In addition, (meth) acrylamide, (meth) acrylonitrile, styrene, vinyl chloride and the like can be used. The copolymerization is not particularly limited, and any known polymerization method can be used.
Solution polymerization using an alcohol such as ethanol or isopropyl alcohol as a solvent is performed. Of course, emulsion polymerization and suspension polymerization are also possible. In such solution polymerization, as a method of charging the monomers, first, the entire amount of the vinyl ester and a part of the oxyalkylene group-containing unsaturated monomer are charged, polymerization is started, and the remaining unsaturated monomers are polymerized for the polymerization period. Arbitrary means such as a method of adding them continuously or in a divided manner, a method of batch charging the former, and the like may be used. The copolymerization reaction is
The reaction is carried out using a known radical polymerization catalyst such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, and lauroyl peroxide. The reaction temperature is selected from the range of 50 ° C. to the boiling point. The saponification is performed by dissolving the copolymer in alcohol and in the presence of an alkali catalyst. Examples of the alcohol include methanol, ethanol, and butanol. The concentration of the copolymer in the alcohol is selected from the range of 20 to 50% by weight. As the saponification catalyst, it is necessary to use an alkali catalyst such as an alkali metal hydroxide or an alcoholate such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate or potassium methylate. It is necessary to use the catalyst in an amount of 1 to 100 mmole equivalent to the vinyl ester. The present invention is not limited to the above-mentioned method. For example, a method of adding an alkylene oxide to PVA (partially saponified or completely saponified) may be used. Thus the content of the base in the PVA-based resin having an oxyalkylene group of the present invention is 5 to 40 wt% against the whole tree fat. Although the PVA resin produced as described above is purified, it is industrially advantageous to wash and purify it with methanol or a mixed solvent of methanol / methyl acetate. At this time, the PVA-based resin has a methanol-soluble content of 5.
It must be 0% by weight or less, and if it exceeds 5.0% by weight, sufficient thermal stability cannot be maintained. Further, the P
VA resin has a viscosity of 1 at 20 ° C. and 4% by weight aqueous solution.
0 centipoise or less. If the viscosity of the non-plastic PVA resin exceeds 10 centipoise, it is difficult to perform melt molding unless the saponification degree is 80 mol% or less. In this case, however, the crystallinity is reduced, the gas barrier property is poor, and the film Poor practicality due to easy blocking phenomenon. The degree of saponification is not particularly limited, but may be 50.
-100 mol%, preferably 80-100 mol% is practical. In addition, as a viscosity measurement method, the absolute viscosity of a 4% by weight aqueous solution at 20 ° C. is determined by a Heppler viscometer (manufactured by Kamishima Seisakusho Co., Ltd.). As a method for measuring the methanol-soluble content, the sample solution is refluxed for about 8 hours using a Soxhlet extractor, and the obtained extract is dried to measure the soluble component weight of the PVA-based resin. In melt-molding the PVA-based resin as described above, there is no particular limitation, and any method such as an extrusion molding method is employed. As the melt molding machine, an ordinary melt molding machine for thermoplastic resin is used, and an inflation die or T
A film having an arbitrary shape is manufactured by attaching a die or the like. The operating conditions of the extruder are as follows:
The temperature of the screw compression section at 30 ° C is 10 to 4
It is preferable to adjust the temperature to 0 ° C. higher. If the temperature of the discharge section is out of the upper limit described above, stable control of working conditions may be difficult, or the PVA-based resin may be thermally decomposed.
On the other hand, if it is less than the lower limit, there is a problem that the fluidity of the resin is reduced. If the temperature of the screw compression section is not set to be higher than the temperature of the discharge section by 10 to 40 ° C., the resin may not be sufficiently kneaded and melted, and it may be difficult to carry out melt molding. The barrel is heated by means such as electric heating, oil heating or steam heating, and the heater is set so that the cylinder is usually divided into three to five parts so that the temperature can be adjusted independently. In the present invention, it is not necessary to add a plasticizer at the time of melt molding, and it is better not to add it in consideration of the quality of a molded product. However, if necessary, a small amount of an additive may be added. . Examples of such a plasticizer include glycerin, diglycerin, ethylene glycol, propylene glycol, trimethylolethane, and trimethylolpropane. In the present invention, even when the above-mentioned plasticizer is used, the amount thereof is small, so it is considered that there is no fear of the film blocking phenomenon. In addition, in performing the melt molding, clay, silica, inorganic powder such as calcium carbonate, or a coloring agent, a surfactant, an antioxidant, a foaming agent, and the like, a known compounding agent which is usually added to a molded product, as appropriate. Can be used. Further, it is possible to carry out melt molding by mixing with not only PVA-based resin alone but also other thermoplastic resins such as polyolefin such as polyethylene and polypropylene, nylon, polyester, polyvinyl chloride and polystyrene. Although the method of producing a film has been mainly described above, the method of the present invention is not limited to this, and molded articles of various shapes such as sheets, rods, pipes, containers, bottles, and fibers can be produced. Can be manufactured,
Specifically, stationery and office supplies such as toys, writing utensils, pods, clips, file members, etc., sanitary supplies such as cotton swabs and tissue cases, medical supplies, sports goods such as golf tees, bottles for packaging agricultural chemicals, molded products containing fertilizer, etc. Agricultural and horticultural supplies, lubricating oil bottles, car parts such as pipes and other mechanical parts, packaging supplies such as foam and other cushioning materials, etc.
It is used for various purposes such as paper core of wrapping paper. The PVA-based resin of the work for the present invention is a polyoxyalkylene group-containing polyvinyl alcohol resin oxyalkylene group-containing vinyl ester polymer obtained by saponification with an alkali catalyst, the content of the oxyalkylene group , is stable thermal stability is extremely good and the melt viscosity by limiting the melt viscosity and methanol solubles.
Therefore, there is no fish eye and no coloring, and it is also possible to prevent the occurrence of mold during molding, so that a molded product of very high quality can always be produced, which is industrially extremely advantageous. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Hereinafter, “parts” or “%” is based on weight unless otherwise specified. Example 1 Method for producing a film: 3.5% methanol-soluble component, viscosity at 20 ° C., 4% , 6.0 centipoise , polyoxyethylene monoallyte
EO- PV with a 10% ether (n = 15) content
After A based resin (degree of saponification 9 5 mol%) was vacuum-dried for 12 hours at 50 ° C., then heated to 220 ° C. Small biaxial extruder as a molten state (PCM-30, manufactured by Ikegai Tekko Co., Ltd.) pellets at It has become. The pellets obtained above were supplied to a conventional extruder equipped with a screw having a diameter of 40 mm / φ, L / D = 28, a rotation speed of 29 rpm, and an inflation die.
Melt molding was performed at 0 ° C. to obtain a film having a thickness of 100 μm. In addition, the presence or absence of dust was examined when melt molding was performed using the PVA-based resin. The degree of coloring, the number of fish eyes and the solvent resistance of the obtained film were measured by the following methods. The melt stability of the PVA resin was measured to determine the viscosity stability. The results are summarized in Table 2. The degree of coloring of the film (3 cm × 3 cm) was measured for lightness and chroma using a # 80 spectrocolorimeter (manufactured by Nippon Denshoku Industries Co., Ltd.). Number of Fish Eyes The number of fish eyes in a 100 cm × 100 cm film was visually observed. Viscosity Stability The viscosity of the resin retained at 210 ° C. for 60 minutes (η 60 minutes) and the viscosity of the resin retained at 210 ° C. for 5 minutes (η 5 minutes) were measured, and the shear rate was determined using a Capillograph (manufactured by Toyo Seiki Co., Ltd.). The value of η60 minutes / η5 minutes was measured at 103 sec-1. Solvent Resistance A disk-shaped test piece (injection molded product) having a diameter of 5 cm and a thickness of 3 mm was sufficiently dried and weighed, and then immersed in dichloroethane for one month. One month later, the test piece was taken out of dichloroethane, the dichloroethane adhering to the surface was wiped off, and the weight was measured to determine the weight increase rate.
The evaluation criteria are shown below. Examples 2 to 8 Experiments were carried out in the same manner as in Example 1 except that the EO-PVA resin shown in Table 1 was used and the viscosity and methanol-soluble content were changed. The results are summarized in Table 2. [Table 1] Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that the methanol-soluble content was changed to 7.6%. The results are collectively shown in Table 2. 20 ° C. Comparative Example 2 Example 1, except that the viscosity using EO-PVA-based resin is 15 centipoises in a 4% Experiments were conducted according to the same embodiment. The results are collectively shown in Table 2. [Table 2] The PVA-based resin of the present invention exhibits, a oxyalkylene group-containing polyvinyl alcohol resin oxyalkylene group-containing vinyl ester polymer obtained by saponification with an alkali catalyst, containing oxyalkylene group
By limiting the amount, viscosity and methanol-soluble content, the PVA-based resin has remarkably good thermal stability and stable melt viscosity. Therefore, since there is no fish eye and no coloring, and it is also possible to prevent rusting during molding, it is possible to always produce a molded product of extremely high quality, which is extremely industrially advantageous.

Claims (1)

(57) Okishiaru formed by saponification with Patent Claims 1] alkali catalyst oxyalkylene group-containing vinyl ester polymer
A polyvinyl alcohol resin containing a kylene group,
The content of the xyalkylene group is 5 to 40 with respect to the whole resin.
The viscosity of a 4% by weight aqueous solution at 20 ° C. is 10 centipoise or less, and the methanol-soluble content is 5%.
Method for producing a polyvinyl alcohol-based resin molded product, which comprises melt molding the oxyalkylene group-containing polyvinyl alcohol-based resin is less than weight percent.