JP2001261911A - Polyvinyl alcohol-based molded form - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject molded form industrially easily obtainable by thermo-melt forming without discoloration and offensive odor emission due to thermal decomposition and also excellent in mechanical properties such as mechanical strength inherent in polyvinyl alcohol. SOLUTION: This molded form is obtained by melt forming of a polyvinyl alcohol-based resin composition comprising (A) 100 pts.wt. of a polyvinyl aocohol-based resin and (B) 0.05-25 pt(s).wt. of a hydrazine-based compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention can be easily obtained industrially by hot-melt molding without generating coloring or off-odor due to thermal decomposition, and polyvinyl alcohol (hereinafter abbreviated as PVA) is inherently used. The present invention relates to a PVA-based molded article having excellent mechanical properties such as strength.

[0002]

2. Description of the Related Art Since the melting point of PVA is very close to the thermal decomposition temperature, melt molding, which is performed with ordinary thermoplastic resins, has problems such as coloring due to thermal decomposition and unpleasant odor due to decomposition products. Almost not done. Therefore, PV
When a molded article is obtained from A, for example, when a film is obtained from PVA, a method of producing a film by a casting method by dissolving in water or an organic solvent capable of dissolving PVA is usually performed. However, in this method, it is necessary to dry a large amount of water and an organic solvent used for dissolving PVA, and the production process is complicated and production efficiency is poor. Further, since a large amount of heat energy is required for drying, the production cost is reduced. There was a problem that the cost was high.

[0003] As a method for obtaining a PVA-based molded article by melt molding, there has been proposed a method of adding a large amount of a plasticizer such as water, glycerin or polyethylene glycol to lower the melting point and melt viscosity. However, if a large amount of water is used, a drying step is required, and if a large amount of a plasticizer is used, the obtained molded body is likely to be sticky and easily blocked, and furthermore, mechanical properties such as strength inherent in PVA are required. There is a problem that physical properties are impaired.

In addition, copolymerization of PVA with other monomers and P
VA is chemically modified with other functional groups and then modified by PVA.
Many methods have been proposed for lowering the melting point of melamine and for enabling melt molding. For example, JP-A-62-229135 discloses a method using PVA having an acrylic alcohol unit, JP-A-63-289581 discloses a method using PVA having an α-olefin unit, and JP-A-3-20.
Japanese Patent No. 3932 discloses P containing an oxyalkylene group.
A method using VA has been proposed. However, in these methods, the production cost of the PVA-based resin is increased, such as the necessity of producing PVA under special conditions, and the necessity of further chemical treatment after the production of PVA. There is a disadvantage that the process becomes complicated.

[0005] There have also been proposed many methods of adding a thermal decomposition inhibitor of PVA to carry out melt molding. For example, an acid having a PKa of 5.0 or less is added in an amount of 0.1 to 10 mol per 1 mol of an alkali metal acetate of PVA to dissociate the alkali metal acetate contained in PVA, thereby removing acetic acid from the PVA system. Method (JP-A-6-136139)
However, this method requires a mechanism for removing acetic acid generated in the melt molding machine, and since a generally used melt extrusion molding machine does not have such a mechanism, a step of removing acetic acid is required. However, a two-step process including a step of actually performing extrusion molding is required, and there are problems that the molding equipment becomes complicated and that the manufacturing cost increases.

Another method is to add a metal salt such as lithium chloride as a thermal decomposition inhibitor for PVA (Japanese Patent Laid-Open No. 4-2).
No. 02535) has been proposed, but these methods have insufficient thermal decomposition preventing effects.

As described above, various methods have been studied in the past for a method of performing melt molding of a PVA-based resin.
At present, there is almost no example of producing a molded body of a PVA-based resin by melt molding.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and can be industrially easily obtained by hot-melt molding without coloring and unpleasant odor due to thermal decomposition.
Moreover, it is an object of the present invention to provide a PVA molded article having excellent mechanical properties such as strength inherent in a PVA-based resin.

[0009]

The present invention solves the above-mentioned problems, and comprises a PVA-based resin (A) and a hydrazine-based compound (B), and the content of the hydrazine-based compound is reduced. With respect to 100 parts by weight of the PVA-based resin, 0.
A PVA-based molded product obtained by melt-molding a PVA-based resin composition in an amount of from 0.5 to 25 parts by weight. The polyvinyl alcohol-based resin composition has a plasticizer of 0.05 to 100 parts by weight based on the polyvinyl alcohol-based resin.
It is desirable to contain 20 parts by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the PVA resin (A) used in the present invention, those obtained by various known methods are used. For example, a fatty acid vinyl ester obtained by saponifying a fatty acid vinyl ester obtained by a known polymerization method such as lump, solution, suspension, emulsification or the like by a known method is used. Here, examples of the fatty acid vinyl ester used include, but are not limited to, vinyl formate, vinyl propionate, and vinyl butyrate. Among them, vinyl acetate is industrially preferable.

The degree of saponification of the PVA-based resin is not particularly limited and is usually 50 to 99.5 mol%, and can be appropriately selected depending on the use of the molded article. Among them, water resistance,
When a molded article excellent in oil resistance and oxygen barrier properties is obtained, a saponification degree of 98 mol% or more is used, and when a molded article excellent in water solubility or dispersibility is obtained, a saponification degree of 65 mol% is used.
Generally, those having a concentration of about 96 mol% are used.

Although the average degree of polymerization of PVA is not particularly limited, it is usually from 100 to 4000, more preferably from 3 to 4.
00 to 2500. If the average degree of polymerization is less than 100, the mechanical strength of the obtained molded article tends to decrease. If it exceeds 4000, the melt viscosity at the time of melting tends to be high, and molding tends to be difficult.

As the PVA resin used in the present invention, two or more PVA resins may be used in combination. The PVA-based resin used in the present invention may be one copolymerized with another copolymerizable monomer as long as the effect of the present invention is not impaired. The polymer terminal may be modified.

Examples of the monomers copolymerizable with the above-mentioned vinyl acetate include olefins such as ethylene and propylene: acrylic acid, methacrylic acid, crotonic acid, and the like.
Polymerizable monocarboxylic acids such as isocrotonic acid: polymerizable dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid: polymerized dicarboxylic anhydrides such as maleic anhydride: esters of polymerizable monocarboxylic acids and polymerizable dicarboxylic acids; Salts: Polymerizable acid amides such as acrylamide and methacrylamide: acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate: methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate: Vinyl halides such as vinyl chloride and vinyl fluoride: vinylidene halides such as vinylidene chloride and vinylidene fluoride:
Monomers having a glycidyl group such as allyl glycidyl ether and glycidyl methacrylate: methyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, etc. Vinyl ethers: Nitriles such as acrylonitrile and methacrylonitrile: Allyl compounds such as allyl acetate, allyl chloride, polyoxyethylene allyl ether, and polyoxypropylene allyl ether: Vinyl silyl compounds such as vinyltrimethoxysilane, and isopropenyl acetate But not limited to this.

Examples of the chain transfer agent for modifying the terminal of the polymer include aldehydes and halogen-containing compounds, but are not limited thereto.

Further, as the PVA resin used in the present invention, a resin obtained by washing a PVA-based resin with water or methanol may be used in order to remove an alkali metal salt of metal acetate.

As the hydrazine compound (B) used in the present invention, various compounds are used.
Hydrazine hydrate, hydrazine monohydrate or salt, form hydrazide, acetohydrazide, propionic hydrazide, lauric hydrazide, methyl carbazate, ethyl carbazate, semicarbazide hydrochloride, stearic hydrazide, salicylic hydrazide, p- Hydroxybenzoic acid hydrazide, benzoic acid hydrazide, 1
-Naphthoic acid hydrazide, carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacidide dicanide dihydrazide Hydrazide, terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 4,4'-
Bisbenzenedihydrazide, 1,4-cyclohexanedihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, iminodiacetic acid dihydrazide, N, N'-hexamethylenebissemicarbazide, itaconic acid dihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, citric acid trihydrazide, 1,2 , 3-benzenetrihydrazide,
Compounds having a hydrazino group or a hydrazide group in a molecule such as 1,4,5,8-naphthoic acid tetrahydrazide, nitriloacetic acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, pyromellitic acid tetrahydrazide, and N-aminopolyacrylamide; Hydrazine derivatives such as carbohydrazide diacetone hydrazone and dihydrazide diacetone hydrazone adipate obtained by reacting a ketone compound with the above hydrazine compound can be used, but are not limited thereto.

Of these, a water-soluble hydrazine compound is preferred from the viewpoint of compatibility with the PVA-based resin. Further, adipic dihydrazide and carbodihydrazide are preferred.

The content of the hydrazine compound (B) of the present invention is 0.1 to 100 parts by weight of the PVA resin (A).
0 to 25 parts by weight. Preferably, it is 0.1 to 15 parts by weight.

When the content of the hydrazine compound is less than 0.05 parts by weight, the effect of preventing coloring and unpleasant odor due to thermal decomposition during melt molding is insufficient. In addition, when the amount exceeds 25 parts by weight, the effect of preventing coloring and unpleasant odor due to thermal decomposition reaches a peak,
It is not preferable because it is disadvantageous in terms of cost.

In the present invention, a plasticizer can be further contained. As the plasticizer, any of those known as plasticizers for PVA can be used. For example,
Polyethylene glycol, glycerin, diglycerin,
Examples include, but are not limited to, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, sorbitol, pentaerythritol, water, and the like.

The content of the plasticizer is as follows.
The amount is preferably 0.5 to 20 parts by weight, more preferably 1 to 15 parts by weight, per 100 parts by weight. By using a plasticizer, the melt viscosity is reduced, the moldability is improved, and the elongation of the obtained molded body is increased.

When the content of the plasticizer is more than 20 parts by weight,
The physical properties of the molded article may be adversely affected, and the plasticizer may bleed out, resulting in a problem that the appearance of the molded article may be impaired or sticky.

The PVA-based resin composition of the present invention comprises P
It is obtained by mixing a VA resin and a hydrazine compound. If necessary, other than the above-mentioned plasticizers, fillers such as clay, silica, calcium carbonate, titanium (Ti) compounds, nickel (Ni) compounds, and coloring agents, etc. , Stabilizers, lubricants,
Various additives such as an antiblocking agent, a fragrance, a reinforcing fiber, and an ultraviolet absorber can be blended.

Further, high-molecular compounds such as starch, cellulose, polyethylene, polypropylene, polystyrene, polyester, polyamide, polyurethane and the like can be blended as long as the effects of the present invention are not impaired.

It can be obtained by mixing a PVA resin and a hydrazine compound. The mixing method is not particularly limited, and a method in which the PVA resin and the hydrazine compound are charged at once and then melt-mixed, or a method such as water is used. A method of absorbing a hydrazine-based compound dissolved or dispersed in a plasticizer of PVA into PVA can be used, but the method is not limited thereto.

The PVA-based resin composition of the present invention is melt-molded by various known methods. For example, there are an extrusion molding method, an injection molding method, a transfer molding method, a lamination molding method, and the like. In addition, the extrusion molding method includes blow molding, inflation molding, co-extrusion molding and the like.

The molded articles obtained by the present invention are films, bottles, sheets, hoses, tubes, containers, fibers,
It can be used as a foam or the like. In particular, if a PVA-based resin having a degree of saponification of 98 mol% or more is used, it can be used for applications requiring oil resistance, fragrance retention, oxygen barrier properties, etc. Use of a PVA resin having a degree of conversion of 60 to 97 mol% is useful for applications requiring water solubility and water dispersibility.

[0029]

The present invention will be described more specifically with reference to the following examples.

Example 1 100 parts by weight of a PVA resin (average degree of polymerization 1000, saponification degree 87.4 mol%) and 2 parts by weight of adipic dihydrazide powder as a hydrazine compound were dry-blended, and glycerin was used as a plasticizer. After adding 10 parts by weight and mixing well, glycerin was absorbed by the PVA resin at 60 ° C.

Using this resin as a raw material, a thickness of 40 μm and a folding width of 1 are melt-formed using an inflation film forming machine.
A 3 cm film was obtained. The film forming conditions at this time are shown below. (Film-forming conditions) Film-forming machine stand: Toyo Seiki Seisakusho Co., Ltd. Labo Plastomill Dice: Inflation film-forming annular die (gap = 0.5 mm, diameter = 2.5 cm) Cylinder temperature: 200 ° C. Die temperature: 180 ° C Screw rotation speed: 30 rpm Discharge amount: 15 g / min The following evaluation test was performed using this film. The test results showed that the strength and elongation were sufficiently high as shown in Table 1, and there was no coloring due to unusual odor or thermal decomposition.

Evaluation Test Strength and elongation of the film The above film was conditioned at 20 ° C. and 65% RH for 24 hours, and then, using a strograph R3 manufactured by Toyo Seiki Co., Ltd., a distance between chucks of 30 mm and a tensile speed of 50 mm / min. The strength and elongation at break of the film under the conditions were measured. 2. Yellowing resistance The above film was converted to a spectroscopic color difference meter CO from Nippon Denshoku Industries Co., Ltd.
The yellowness (YI) of the transmitted light was measured using H-300A, and the yellowing resistance was evaluated based on the following criteria. ◎: YI = less than 1.0 ○: YI = 1.0 to less than 3.0 Δ: YI = 3.0 to 10.0 ×: YI = 10.0 or more Off-flavor The odor of the film was evaluated according to the following criteria. ◎: No smell was felt. ：: Almost no smell is felt. Δ: Decomposition odor of PVA is felt. ×: Severe PVA decomposition odor. 4. Comprehensive evaluation The above evaluations were comprehensively evaluated according to the following criteria. ：: There is no coloring due to thermal decomposition or off-flavor due to decomposition gas, and both the film strength and elongation are high. ：: Almost no coloration due to thermal decomposition or generation of off-flavor due to decomposition gas, and both film strength and elongation are high. X: One or more performances out of the coloring by thermal decomposition and the generation of off-flavor due to decomposition gas, the strength and elongation of the film are inferior.

Example 2 A film was obtained in the same manner as in Example 1, except that the amount of adipic dihydrazide was changed to 7 parts by weight. An evaluation test was performed in the same manner as in Example 1 using this film. As shown in Table 1, the results were both sufficiently high in strength and elongation, and there was no off-odor or coloring due to thermal decomposition.

Example 3 A film was obtained in the same manner as in Example 1 except that the amount of adipic dihydrazide was changed to 0.3 part by weight. An evaluation test was performed in the same manner as in Example 1 using this film. As shown in Table 1, the results were both sufficiently high in strength and elongation, and there was no off-odor or coloring due to thermal decomposition.

Example 4 A film was obtained in the same manner as in Example 1 except that the hydrazine compound was changed to sebacic acid dihydrazide. An evaluation test was performed in the same manner as in Example 1 using this film. As shown in Table 1, the results were both sufficiently high in strength and elongation, and there was no off-odor or coloring due to thermal decomposition.

Example 5 The same conditions as in Example 1 were used except that the PVA resin was changed to one having an average polymerization degree of 600 and a saponification degree of 98.4 mol%, and the film forming conditions were changed to those shown below. A film was obtained. Using this film, an evaluation test was performed in the same manner as in Example 1. As shown in Table 1, the results were both sufficiently high in strength and elongation, and there was no off-odor or coloring due to thermal decomposition. (Film-forming conditions) Film-forming machine stand: Labo Plastomill manufactured by Toyo Seiki Seisaku-sho, Ltd. Die: Ring die for inflation film-forming (gap = 0.5 mm, diameter = 2.5 cm) Cylinder temperature: 220 ° C. Die temperature: 210 C Screw rotation speed: 30 rpm Discharge amount: 15 g / min Using this film, an evaluation test was performed in the same manner as in Example 1. As shown in Table 1, the test results were both sufficiently high in strength and elongation, and there was no off-odor or coloring due to thermal decomposition.

Example 6 100 parts by weight of a PVA resin (average degree of polymerization: 1000, saponification degree: 87.4 mol%) and 4 parts by weight of adipic dihydrazide powder as a hydrazine compound were dry-blended. This PVA resin composition was melt-molded using an inflation film forming machine to obtain a film having a thickness of 40 μm and a fold width of 13 cm. The film forming conditions at this time are shown below. (Film-forming conditions) Film-forming machine stand: Labo Plastomill manufactured by Toyo Seiki Seisaku-sho, Ltd. Die: Ring die for inflation film-forming (gap = 0.5 mm, diameter = 2.5 cm) Cylinder temperature: 210 ° C. Die temperature: 200 C Screw rotation speed: 30 rpm Discharge amount: 15 g / min Using this film, an evaluation test was performed in the same manner as in Example 1. The test results showed that the strength and elongation were sufficiently high as shown in Table 1, and there was no coloring due to unusual odor or thermal decomposition.

Example 7 The same conditions as in Example 6 were used, except that the PVA resin was changed to one having an average polymerization degree of 600 and a saponification degree of 98.4 mol%, and the film forming conditions were changed to those shown below. A film was obtained. Using this film, an evaluation test was performed in the same manner as in Example 1. As shown in Table 1, the results were both sufficiently high in strength and elongation, and there was no off-odor or coloring due to thermal decomposition. (Film formation conditions) Cylinder temperature: 235 ° C. Die temperature: 225 ° C. Screw rotation speed: 30 rpm Discharge rate: 15 g / min

Comparative Example 1 A film was prepared in the same manner as in Example 1 except that no hydrazine compound was added. Using this film, an evaluation test was performed in the same manner as in Example 1. As a result, as shown in Table 1, the film had severe coloring due to thermal decomposition and severe odor due to decomposition gas.

Comparative Example 2 A film was prepared in the same manner as in Example 1 except that the amount of adipic dihydrazide was changed to 0.01 part by weight. Using this film, an evaluation test was performed in the same manner as in Example 1. As shown in Table 1, as shown in Table 1, the effect of preventing decomposition was not sufficient, and the film was colored by thermal decomposition and generated an unpleasant odor due to decomposition gas.

Comparative Example 3 A film was prepared in the same manner as in Example 5 except that no hydrazine compound was added. PVA during molding
Was severely decomposed and a film could not be obtained.

Comparative Example 4 A film was prepared in the same manner as in Example 6 except that no hydrazine compound was added. Using this film, an evaluation test was performed in the same manner as in Example 1. Result is,
As shown in Table 1, the film was colored by thermal decomposition and had an unpleasant odor due to decomposition gas.

[0043]

[Table 1]

[0044]

According to the present invention, a PVA molded article having excellent mechanical properties such as strength inherent in PVA can be industrially easily produced by hot-melt molding without coloring and unpleasant odor due to thermal decomposition. Can be obtained.

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Claims (2)

[Claims] 1. A composition comprising a polyvinyl alcohol resin (A) and a hydrazine compound (B), wherein the content of the hydrazine compound is 0.05 to 25 parts by weight based on 100 parts by weight of the polyvinyl alcohol resin. A polyvinyl alcohol-based molded product obtained by melt-molding a polyvinyl alcohol-based resin composition. 2. The polyvinyl alcohol-based resin composition according to claim 1, wherein the polyvinyl alcohol-based resin composition contains 0.05 to 20 parts by weight of a plasticizer based on 100 parts by weight of the polyvinyl alcohol-based resin. Alcohol-based molded body.