JP2002212371A - Polyvinyl alcohol-based resin composition - Google Patents

Abstract

(57) [Problem] To provide a PVA-based resin composition which suppresses thermal deterioration of a PVA-based resin and has excellent thermal stability. The composition comprises a polyvinyl alcohol-based resin (A), a monovalent copper compound (B), and an alkali metal halide compound (C), and the mixing ratio of the component (B) is 100 parts by weight of the component (A). 1 to 5 parts by weight, and the compounding amount of the component (C) is 10 per 100 parts by weight of the component (B).
The above problem is solved by the polyvinyl alcohol-based resin composition in an amount of 0 to 1000 parts by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyvinyl alcohol resin composition comprising a polyvinyl alcohol resin (hereinafter abbreviated as PVA resin), a monovalent copper compound and an alkali metal halide compound.

[0002]

2. Description of the Related Art PVA-based resins are typical water-soluble resins, and although having a different dissolution rate depending on the degree of saponification, have the property that they are dissolved in water and lose their shape. In addition, PVA-based resin has excellent mechanical strength,
Taking advantage of superior characteristics compared to other resins, fiber glue,
It is widely used as a coating agent for films and papers. Furthermore, the PVA-based resin is a resin having biodegradability, and the environment is not contaminated by the PVA-based resin dissolved in water. When heat-treating and thermoforming a PVA-based resin, thermal stability (coloring, odor, viscosity, etc.) is extremely important. In particular, since the melting point of the PVA resin is close to the crystal melting point, the thermal stability is extremely low as compared with polyethylene, polypropylene, polyvinyl chloride, and the like, and the thermal degradation is remarkable during melt molding. In order to improve the thermal stability of the PVA-based resin, methods such as eliminating impurities such as sodium acetate in the resin as much as possible, copolymerizing the second component, lowering the degree of saponification, adding a plasticizer or water, etc. Has been devised to lower the melting point. Such a method is certainly effective in lowering the melting point of the PVA-based resin, but on the other hand, causes a decrease in the crystallization speed and the reached crystallinity, and as a result, the mechanical properties and the like are reduced. It also causes a decrease in productivity due to the extension of the molding cycle. P
The methods proposed as methods for improving the thermal stability of VA-based resins have the above-mentioned problems and are not all satisfactory, and further improvement measures are desired. Factors that affect the thermal stability of the PVA-based resin include a degree of polymerization, a degree of saponification, and a content of an alkali metal salt. However, in practice, it has not been clarified exactly how these factors cause thermal degradation to proceed. For this reason, no effective method has been found for improvement measures.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a PVA-based resin composition which suppresses thermal deterioration of a PVA-based resin and has excellent thermal stability.

[0004]

According to the present invention, the above object is achieved by a polyvinyl alcohol resin (A), a monovalent copper compound (B) and an alkali metal halide compound (C).
(B) per 100 parts by weight of component (A)
Is 0.1 to 5 parts by weight, and the component (B) 10
The mixing ratio of the component (C) to 0 parts by weight is 100 to 10
It has been found that this is achieved by a polyvinyl alcohol-based resin composition which is 00 parts by weight.

Hereinafter, the present invention will be described in detail. In the PVA-based composition of the present invention, a heat-meltable PVA-based resin is used as the component (A), which can be obtained by polymerizing a vinyl ester-based monomer and then saponifying it. . Here, examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, and vinyl pivalate, and vinyl acetate is often used industrially.

The PVA resin used in the present invention has 4 carbon atoms.
The following α-olefin unit may be contained, and specific examples of the α-olefin include, for example, ethylene, propylene, 1-butene, and isobutene.
In consideration of water resistance and moisture absorption, ethylene is more preferable. The content of the α-olefin unit contained in the PVA-based resin is preferably 0 to 20 mol%. When the content of the α-olefin unit exceeds 20 mol%, the solubility of the PVA-based resin in water decreases.

[0007] The PVA resin used in the present invention also includes
Alkyl vinyl ether units having 4 or less carbon atoms and / or
Or a hydroxyalkyl vinyl ether unit, and specific examples thereof include, for example, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, hydroxyethyl vinyl ether, and hydroxybutyl vinyl ether. Is mentioned.
The content of the alkyl vinyl ether and / or hydroxyalkyl vinyl ether contained in the PVA-based resin is preferably 0 to 20 mol%. If the content exceeds 20 mol%, the solubility of the PVA-based resin in water is reduced.

The degree of polymerization and the degree of saponification of the PVA resin used in the present invention are not particularly limited. However, considering the mechanical strength and morphological stability of the obtained molded product, and the viscosity stability during molding, etc. Those having a degree of polymerization of 100 to 2000 are often used, and those having a polymerization degree of 200 to 1700 are preferable.
For the same reason, the degree of saponification is also 40 mol%.
The above is preferable, and the one with 60 mol% or more is more preferable.

[0009] Commercially available PVA-based resins usually contain about 0.1% of residual sodium acetate. In the present invention, the amount of residual sodium acetate contained in the PVA resin is not particularly limited, but is preferably 0.05% or less in consideration of the mechanical strength, coloring, moldability, and the like of the obtained molded product. More preferably, it is 0.01% or less.

[0010] PVA that can be used in the present invention
As long as the system resin does not impair the effects of the present invention, even if it contains a monomer unit other than a vinyl alcohol unit, a vinyl ester unit, an α-olefin unit, an alkyl vinyl ether unit, and a hydroxyalkyl vinyl ether unit. Good. Examples of such a monomer unit include unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, (anhydrous) maleic acid, (anhydride) itaconic acid or salts thereof or alkyl having 1 to 18 carbon atoms. Esters: acrylamide, C-C18 N-alkylacrylamide, N, N-dimethylacrylamide, 2
-Acrylamides such as acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or a salt thereof or a quaternary salt thereof; methacrylamide, a C1-C18 N-alkylmethacrylamide, N, N-dimethylmethacrylamide, Methacrylamides such as 2-methacrylamidopropanesulfonic acid or a salt thereof, methacrylamidopropyldimethylamine or an acid salt or a quaternary salt thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide and N-vinylacetamide Vinyl cyanides such as acrylonitrile and methacrylonitrile; allyl ethers such as allyl acetate, propyl allyl ether, butyl allyl ether and hexyl allyl ether; vinyl chloride and vinylyl chloride Vinyl halides such as vinyl chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxy vinyl silane; monomers having an oxyalkylene group; isopropenyl acetate; 3-buten-1-ol; -Penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-
Hydroxy group-containing α-olefins such as decene-1-ol and 3-methyl-3-buten-1-ol; fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride or A monomer having a carboxyl group derived from itaconic acid or the like; ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-
Monomers having a sulfonic acid group derived from acrylamide-2-methylpropanesulfonic acid; vinyloxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, vinyloxyethyldimethylamine, vinyloxymethyldiethylamine, N-acrylamidomethyl Trimethylammonium chloride,
Monomers having a cationic group derived from N-acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethyl and the like can be mentioned. Among these monomers, allyl ethers such as allyl acetate, propyl allyl ether, butyl allyl ether, and hexyl allyl ether, from the viewpoint of availability, copolymerizability and melt moldability of the obtained copolymer, Monomer having an oxyalkylene group, 3-butene-
Hydroxy such as 1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol and 3-methyl-3-buten-1-ol; Monomers derived from group-containing α-olefins are preferred. The content of these monomers contained in the PVA-based resin is usually 20 mol% or less, and more preferably 10 mol% or less.

Examples of the method for polymerizing the vinyl ester monomer include known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is carried out without a solvent or in a solvent such as an alcohol is usually employed. Examples of the alcohol used as a solvent during the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. As the initiator used for the polymerization, for example, α, α′-azobisisobutyronitrile, 2,2
2′-azobis (2,4-dimethylvaleronitrile),
Known initiators such as azo initiators such as benzoyl peroxide and n-propyl peroxycarbonate, and peroxide initiators are exemplified. The polymerization temperature is not particularly limited, but is preferably in the range of -30 to 150 ° C.

The vinyl ester polymer obtained by the above polymerization method is saponified by a known method. As the method, for example, saponification is performed in a state of being dissolved in alcohol. Alcohol used for this purpose includes:
Lower alcohols such as methyl alcohol and ethyl alcohol are exemplified, and methyl alcohol is particularly preferably used. The alcohol used in the saponification reaction may contain a solvent such as acetone, methyl acetate, ethyl acetate, benzene or the like as long as it is 40% by weight or less. As a catalyst used for the saponification reaction, an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an alkali catalyst such as sodium methylate, or an acid catalyst such as a mineral acid is used. The temperature of the saponification reaction is not particularly limited, but is preferably in the range of 20 to 60C. When a gel-like product precipitates with the progress of the saponification reaction, the product is pulverized at that time, washed, and dried to obtain the PVA-based resin as the component (A).

The PVA-based resin composition of the present invention contains a monovalent copper compound in addition to the above-mentioned PVA-based resin. Examples of the monovalent copper compound include cuprous chloride, cuprous bromide, cuprous iodide, and the like. These copper compounds can be used alone or in combination of two or more. Also,
These copper compounds are used in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the PVA resin of the component (A).
Used in parts by weight. The compounding ratio of the copper compound is 0.
When the amount is less than 1 part by weight, the heat stabilizing effect by addition is not sufficiently exhibited, and when the compounding ratio of the copper compound exceeds 5 parts by weight, the thermal stability of the PVA-based resin at the time of melt molding becomes poor. , Decomposition, gelation and coloring become remarkable.

The PVA-based resin composition of the present invention contains an alkali metal halide compound in addition to the above-mentioned PVA-based resin and a monovalent copper compound. Specific examples of the alkali metal halide compounds include lithium chloride, lithium bromide, lithium iodide, sodium fluoride, sodium chloride, sodium bromide, sodium iodide, potassium fluoride, potassium chloride, potassium bromide, and iodide. Potassium and the like. Of these, potassium iodide is particularly preferred. The alkali metal halide compound is used in an amount of 100 to 1000 parts by weight, preferably 200 to 500 parts by weight, based on 100 parts by weight of the copper compound. When the compounding ratio of the alkali metal halide is less than 100 parts by weight with respect to the copper compound, the heat stabilizing effect by addition is not sufficiently exhibited, and the compounding ratio of the alkali metal halide is 100 parts by weight of the copper compound. If the amount exceeds 1000 parts by weight, the thermal stability of the PVA-based resin during melt molding deteriorates, and decomposition, gelation and coloring become significant.

The PVA-based resin composition of the present invention may contain a filler, a plasticizer, another plastic resin, a fragrance, a colorant, and the like, as long as the object of the present invention is not impaired.
Foaming agents, deodorants, extenders, lubricants, release agents, ultraviolet absorbers, antioxidants, processing stabilizers, weather stabilizers, antistatic agents, flame retardants, release agents, reinforcing materials, fungicides, preservatives An ordinary additive such as an agent can be appropriately compounded. The compounding of the filler increases the hardness and rigidity of the molded product obtained from the PVA-based resin composition, gives a sense of weight, and adjusts the rate of water disintegration and biodegradability, and develops anti-blocking properties. This has the effect of providing printability. Specific examples of the filler include talc, clay, calcium carbonate,
Examples include inorganic fillers such as silica, mica, alumina, titanium oxide, zirconium oxide, boron nitride, and aluminum nitride, and organic fillers such as urea-formalin-based resin and melamine-formalin-based resin. The amount of the filler is not particularly limited, but is preferably 0 to 300 parts by weight, more preferably 0 to 100 parts by weight, per 100 parts by weight of the PVA-based resin. Further, the plasticizer lowers the melting point of the PVA-based resin, improves the moldability, and brings effects of imparting flexibility and toughness to the molded product. The plasticizer can be used without any limitation, and those generally used as PVA plasticizers can be used. Specific examples of the plasticizer include polyhydric alcohols such as glycerin, diglycerin and diethylene glycol, polyethers such as polyethylene glycol and polypropylene glycol, sorbitol and compounds obtained by adding ethylene oxide to a polyhydric alcohol such as glycerin, and saccharides. , Polyethers, phenol derivatives such as bisphenol A and bisphenol S, amide compounds such as N-methylpyrrolidone, compounds in which alkylene oxide is added in an amount of about 2 to 4 moles per mole of a trihydric or higher polyhydric alcohol, and Is water and the like. The amount of the plasticizer is not particularly limited, but is preferably 0 to 100 parts by weight, more preferably 1 to 20 parts by weight, per 100 parts by weight of the PVA-based resin. Examples of the other thermoplastic resins include general-purpose resins such as polyethylene, polypropylene, ABS resin, and polystyrene.

The method for preparing the PVA-based resin composition of the present invention is not particularly limited, and a monovalent copper compound and an alkali metal halide compound may be added to the PVA-based resin, and if necessary, a filler, a plasticizer, Only additives may be blended, or these may be melt-kneaded and formed into pellets. Also, kneading the melt kneader while charging the PVA-based resin, the monovalent copper compound and the alkali metal halide compound, the filler, the plasticizer, and the additives separately at a fixed ratio,
It may be pelletized.

The method of melt-molding or heat-treating the PVA-based resin composition of the present invention is not particularly limited, and examples thereof include a compression molding method, a transfer molding method, a reinforced plastic molding method, an injection molding method, and an extrusion molding method. , An extrusion film forming method from a T die, an inflation film forming method, a hollow forming method, a blow forming method, a calender forming method, a foam forming method, a vacuum forming method, a pressure forming method, and the like. PV of the present invention
If desired, another thermoplastic resin may be laminated on the sheet obtained by molding the A-based resin composition.
As other thermoplastic resins that can be used for this purpose, the same thermoplastic resins as those exemplified above as optional components for the PVA-based resin composition of the present invention can be exemplified.

The PVA-based resin composition of the present invention is excellent in heat stability, water solubility, moisture resistance, and biodegradability. It can be effectively used for a wide range of applications such as civil engineering, medical care, packaging, leisure, toys, miscellaneous goods, daily necessities, containers and parts.

[0019]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. In the following Examples and Comparative Examples, “parts” and “%” mean weight basis unless otherwise specified. The degree of polymerization and the degree of saponification are J
It was measured according to IS K6726.

EXAMPLE 1 10% by weight of unmodified PVA having a degree of polymerization of 500, a degree of saponification of 98.5 mol% and a sodium acetate content of less than 0.001%
PVA1 in terms of solid content by adding CuI and KI to an aqueous solution of
After adding 2 parts by weight and 4 parts by weight with respect to 00 parts by weight, they were completely dissolved to prepare a uniform solution. This solution was poured onto a Teflon (registered trademark) sheet measuring 15 cm × 15 cm square and dried by heating at 80 ° C. to obtain a film having a thickness of 80 μm. (1) Evaluation of thermal stability This film was heat-treated in air at 200 ° C. for 2 hours, cooled to room temperature, dissolved in DMSO for 5 hours, and the gel fraction was calculated from the undissolved content by the following formula. Gel fraction (%) = (undissolved content) / (total weight) × 100 (2) Evaluation of coloring situation The coloring situation of the film was visually observed, and the degree was judged according to the following criteria. ○: Small coloring △: Coloring ×: Large coloring

Examples 2 to 4 Films were produced in the same manner as in Example 1 except that the types and amounts of the copper compound and the alkali metal halide compound were changed to those shown in Table 1. The stability and the state of coloring were evaluated. Table 2 shows the evaluation results.
Shown in

Examples 5 to 8 A film was produced in the same manner as in Example 1 except that the polymerization degree, saponification degree and modified species of PVA were changed to those shown in Table 1, and the thermal stability and the thermal stability of the film were evaluated. The coloring status was evaluated. Table 2 shows the evaluation results.

Comparative Example 1 A film was produced in the same manner as in Example 1 except that the copper compound and the alkali metal halide compound were not added, and the thermal stability and coloring of the film were evaluated. Table 2 shows the evaluation results.

Comparative Examples 2 to 5 Films were prepared in the same manner as in Example 1 except that the copper compound and the alkali metal halide compound were added in the amounts shown in Table 1. An evaluation was performed. Table 2 shows the evaluation results.

Comparative Example 6 A 10% by weight aqueous solution of PVA was poured onto a Teflon sheet to obtain a 70 μm thick film. The obtained film was immersed in methanol in which a hindered phenol-based stabilizer “Irganox 1010 manufactured by Ciba Geigy” was dissolved in advance, and then sufficiently dried. Then, in the same manner as in Example 1, heat stability and coloring of the film were obtained. The situation was evaluated. Table 2 shows the evaluation results.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the present invention, the PVA-based resin composition is suppressed from thermal deterioration and has excellent thermal stability. The PVA-based resin composition of the present invention is excellent in heat stability because heat deterioration is suppressed, and is excellent in water solubility, moisture resistance and biodegradability. Therefore, it can be processed into various shapes and used effectively for a wide range of applications such as industrial, agricultural, civil engineering, medical, packaging, leisure, toys, miscellaneous goods, daily necessities, containers and parts.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 BE021 BE031 DD057 DD076 FD010 FD020 GB01 GC00 GG00

Claims (3)

[Claims] 1. A composition comprising a polyvinyl alcohol-based resin (A), a monovalent copper compound (B) and an alkali metal halide compound (C), wherein the mixing ratio of the component (B) to 100 parts by weight of the component (A) is 0. 0.1 to 5 parts by weight, and the blending amount of the component (C) with respect to 100 parts by weight of the component (B) is 10
0 to 1000 parts by weight of a polyvinyl alcohol-based resin composition. 2. A vinyl alcohol resin (A) having a degree of saponification of 60 mol% or more and an α-olefin unit having 4 or less carbon atoms, or an alkyl vinyl ether unit or hydroxyalkyl vinyl ether having 4 or less carbon atoms in an alkyl group. The polyvinyl alcohol resin composition according to claim 1, wherein the composition contains 0 to 20 mol% of a unit. 3. The polyvinyl alcohol resin composition according to claim 2, wherein the α-olefin having 4 or less carbon atoms is ethylene.