JP3137436B2 - Polyvinyl alcohol resin molded article and molding method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced polyvinyl alcohol (hereinafter abbreviated as PVA) resin molded article, and more particularly to an oxyalkylene group-containing PVA resin molded article reinforced with PVA fiber. And its molding method.

[0002]

2. Description of the Related Art A polyvinyl alcohol (hereinafter abbreviated as EO-PVA) resin modified with an oxyalkylene group is known as a resin having excellent solvent resistance and capable of being melt-molded. That is, in order to produce a solvent-resistant PVA molded product, a degree of saponification of about 90 mol% or more is required. However, in order to melt-mold such a highly saponified PVA, a large amount of plasticizer is required. Is indispensable, but the presence of a plasticizer causes a decrease in solvent resistance. Therefore, in order to obtain a molded article in which solvent resistance is required, it is actually necessary to melt-mold a high saponification degree PVA. Was impossible.

However, according to the research conducted by the present applicant, the above-mentioned EO-PVA was developed as a material capable of being melt-molded with high saponification degree PVA without using a plasticizer, and is expected to be put to practical use. I have. However, when trying to use the EO-PVA-based resin in fields such as bottles for agricultural chemicals and various chemicals, particularly where solvent resistance is required, it is necessary to improve the solvent resistance more than before, Since mechanical strength is also required, some countermeasures are required.

[0004] As a countermeasure, to improve the solvent resistance, the degree of saponification may be increased. To improve the mechanical strength, the degree of polymerization of the resin may be increased, or a reinforcing material such as glass fiber may be used. The method of adding is considered.

[0005]

However, if the degree of saponification or the degree of polymerization of the resin is increased, the melt viscosity is increased and the moldability is reduced. Further, addition of an inorganic filler such as glass fiber leads to a disadvantage that the solvent resistance and oxygen barrier property of the molded product are reduced. Therefore, improving the solvent resistance,
The fact that an EO-PVA-based resin molded product having improved mechanical strength can be produced by melt molding is very useful in industry.

[0006]

Means for Solving the Problems Accordingly, the present inventors have
As a result of intensive studies to solve the above problems, an EO-PVA resin molded product containing 0.1 to 50% by weight of a PVA fiber having a saponification degree of 90 mol% or more and an average degree of polymerization of 450 or more, The present inventors have found that they have excellent solvent resistance, oxygen barrier properties, moldability, and mechanical strength, and can easily produce a melt-molded product by melt-molding, and have completed the present invention. Hereinafter, the present invention will be described in detail.

The PVA fiber used in the present invention is PVA fiber.
It is made by spinning a resin into a fibrous form. The PVA resin is not only partially saponified or completely saponified polyvinyl acetate, but also a vinyl ester and a monomer copolymerizable therewith, such as ethylene, propylene, isobutylene, α-octene, α-dodecene, Olefins such as α-octadecene, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid and salts thereof, and mono- or dialkyl esters, etc., nitriles such as acrylonitrile and methacrylonitrile Amides such as acrylamide and methacrylamide, olefinsulfonic acids such as ethylenesulfonic acid, allylsulfonic acid and methallylsulfonic acid or salts thereof, alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, dimethyldiallylamide Compounds having a motor chloride cationic group such as, vinyl ketone, N- vinylpyrrolidone, vinyl chloride, a copolymer saponified vinylidene chloride and the like, not necessarily limited thereto.

The degree of saponification of the PVA resin is at least 90 mol%, preferably at least 95 mol%, and the average degree of polymerization is at least 450, preferably at least 1,000. PV
If the saponification degree of the A-based resin is lower than the above range, improvement in solvent resistance cannot be expected, and if the average polymerization degree is low, improvement in mechanical strength cannot be expected. The melting point of the PVA-based resin is not particularly limited, but is preferably higher than the melting point of the EO-PVA-based resin by 15 ° C. or more. More preferably 20 ° C
That is all. As a method of spinning the PVA resin,
A known method is used, for example, a solution of the PVA (usually 1
(4 to 16% by weight) at 80 to 90 ° C. and extruded through a spinneret into a spinning bath at 10 to 40 ° C. to form a fiber.

As the coagulant, salts such as sodium sulfate, ammonium sulfate and sodium phosphate and alkalis such as sodium hydroxide can be used, but industrially, aqueous sodium sulfate solution is mainly used due to its coagulation ability and economy. Examples of a practical spinning solution using such a coagulant include a saturated aqueous solution of sodium sulfate and a saturated aqueous solution of ammonium sulfate, and a crosslinking agent or the like may be added to this solution. Further, as the spinning solution, not only an aqueous solvent but also an organic solvent such as an alcohol solvent such as methanol can be used.

[0010] Regarding the spinneret, a nozzle having an arbitrary shape such as a circle or a corner is used, and an arrangement such as a crosshair, a radiation, or a star is employed. Water resistance treatment such as acetal treatment is appropriately performed to obtain a fiber length of 0.5 to 5 mm, preferably 1 to 3 mm, and a fiber diameter of 5 to 20 d (denier), preferably 10 to 15 d.
(Denier) is preferably used, but is not limited thereto. The EO-PVA-based resin of the present invention is a modified PVA-based resin containing an oxyalkylene group, which is obtained by reacting PVA with an alkylene oxide or graft-polymerizing vinyl acetate in the presence of polyoxyalkylene glycol. And Japanese Patent Application Laid-Open
-155408-containing unsaturated monomers containing an oxyalkylene group (for example, polyoxy (meth) acrylate, polyoxypropylene (meth)
Acrylate, polyoxyethylene (meth) acrylamide, polyoxypropylene (meth) acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene (meth) allyl ether , Polyoxypropylene (meth) allyl ether, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, etc.) and vinyl acetate.

The saponification degree, average polymerization degree, melting point, oxyalkylene group content and the like of the EO-PVA resin are not particularly limited. Mol%, average degree of polymerization 200 to 120
0, melting point 170-220 ° C., oxyalkylene group content 0.1-5 mol%. The greatest feature of the present invention is that the EO-PVA-based resin contains the above-mentioned PVA-based fiber, thereby improving the molded product of the EO-PVA-based resin. Further, the content of the PVA-based fiber in the EO-PVA-based resin needs to be 0.1 to 50% by weight, and preferably 1 to 30% by weight. If the content is less than 0.1% by weight, there is no effect of adding the PVA-based fiber, and the object of the present invention cannot be achieved. Conversely, if it exceeds 50% by weight, the moldability is impaired. The E containing PVA-based fibers
Production of a melt-molded product of an O-PVA-based resin is carried out under substantially anhydrous conditions as follows. The term "substantially anhydrous" means that about 5% by weight or less of water may remain, but desirably, the water content is 1% by weight or less, especially 0.1% by weight.
5% by weight or less.

At the time of melt molding, a plasticizer such as a polyhydric alcohol can be blended. However, flexibility can be obtained without using a plasticizer, and the use of a plasticizer deteriorates the properties of a molded product. It is better not to use it. At the time of melt molding, various additives such as a filler, a colorant, an antioxidant, and a stabilizer can be blended in addition to the PVA-based fiber. Other polymers can be blended within a range that does not impair the purpose of the present invention. As a method of adding the PVA-based fiber, there are a method of mixing and melt-forming a PVA-based fiber with an EO-PVA-based resin pellet, and a method of melt-forming a pellet containing the PVA-based fiber. As a melt molding method, an injection molding method, an extrusion molding method,
An arbitrary melt molding method such as a transfer spinning method, melt spinning, and lamination is adopted. Particularly important among the melt molding methods are an injection molding method and an extrusion molding method.

The injection conditions include a cylinder (compression section)
The conditions of a temperature of 180 to 215 ° C, a mold temperature of 30 to 100 ° C, and an injection pressure of 500 to 2000 kg / cm ² are suitably adopted. Although EO-PVA-based resin can be injection-molded, molding is more difficult than other general-purpose molding resins, so strict conditions must be set. Extrusion molding includes blow molding, inflation molding, co-extrusion molding,
Extrusion coating is also included.

In the extrusion molding, it is desirable to set the temperature of the screw compression section and the measuring section to 180 to 220 ° C. In any case, the molding temperature (compressed portion) at the time of melt molding must be a temperature at which the EO-PVA-based resin melts but the PVA-based fibers do not melt, and is a temperature lower than the melting point of the PVA-based fibers by 10 ° C. or more. Must be melted.
In consideration of the melting points of the EO-PVA-based resin and the PVA-based fiber, the melting is actually performed at about 180 to 220 ° C. as described above. The EO-PVA-based resin molded product of the present invention thus obtained is widely used in applications such as fibers, films, sheets, pipes, tubes, bottles, leak-proof membranes, sponges, etc. It is useful for packaging applications requiring solvent resistance, such as chemicals and agricultural chemicals.

[0015]

The EO-PVA resin molded product of the present invention is PVA
Since it is reinforced with a system fiber, it is a molded article having excellent solvent resistance and mechanical strength and good melt moldability.

[0016]

The present invention will be specifically described below with reference to examples. In Examples, “parts” and “%” are based on weight unless otherwise specified. First, PVA-based fibers (PVA-1 to 6) as shown in Table 1 were prepared.

[0017]

Table 1 PVA fiber Average degree of polymerization Degree of saponification Melting point Fiber shape (mol%) (° C) (d × mm) PVA-1 1500 99.0 220 13 × 1.5 〃 2500 99.5 2259 × 1.5 〃 3 2500 99.1 221 5 × 2.0 ４ 4 1000 97.0 216 10 × 2.0 〃 5 500 85.0 180 8 × 1.5 ６ 6 200 98.5 214.8 × 1. 5

(Production of EO-PVA resin) Polyoxyethylene monoallyl ether having an average number of moles of oxyethylene added of 25 and vinyl acetate are copolymerized in methanol in the presence of azobisisobutyronitrile, Then, after the remaining monomer was driven off, a methanol solution of sodium hydroxide was added to perform saponification. The copolymer was separated from the slurry produced by the saponification reaction by filtration, washed and dried to obtain the desired EO-PVA resin (EO-1). The above EO
The degree of saponification of the PVA-based resin (EO-1) is 90 mol%,
The average degree of polymerization was 450, the amount of modification (oxyalkylene group added mol%) was 1.2 mol%, and the melting point was 191 ° C.
Hereinafter, EO-PVA-based resins (EO-2 to 5) shown in Table 2
Was obtained according to the above.

[0019]

Table 2 EO-PVA resin oxyalkyl group Degree of saponification Average degree of polymerization Modification amount Melting point- containing monomer (mol%) (mol%) (° C) EO-1 polyoxyethylene 90 450 1.2 191 monoallyl ether 2 ９２ 92 650 1.1 193 〃 3 ８８ 88 350 1.3 185 〃 4 ８５ 85 500 1.5 178 ５ 5 〃 96 400 2.5 204

Example 1 The EO-PVA-based resin (EO-1) was 0.1% in water content.
After drying to the following, it was supplied to an extruder at 200 ° C., extruded into a strand, and then cut into pellets. This pellet and PVA-based fiber (PVA-1) were mixed with 94
/ 6 (6% of PVA-based fiber) and then subjected to melt extrusion molding under the following conditions. Extruder Twin screw extruder Screw L = 1150mm, D = 40mmφ L / D = 28.75 Number of rotations 50rpm Cylinder temperature Compressor 200 ° C Round die temperature 195 ° C

The obtained mixed pellets are injected into an injection molding machine (melting temperature: 200 to 210, injection pressure: 1000 kg / primary).
cm ² , secondary 800 kg / cm ² -1 cycle 28se
In c), a disk for measuring the solvent resistance, a test piece for measuring the impact strength, and a dumbbell for measuring the tensile strength were molded, and the respective physical properties were measured. Examples 2 to 6 Molded articles were prepared in the same manner as in Example 1 with the blending compositions and melting temperatures shown in Table 3, and the physical properties of the molded articles were examined as in Example 1.

Comparative Examples 1 to 6 EO-PVA resins and PVA shown in Tables 1 and 2
The blending composition shown in Table 3 (Comparative Example 1 was EO-P
Melt molding was performed in the same manner as in Example 1 at a melting point of the VA-based resin, and a molded article for measuring physical properties was prepared. Similarly, solvent resistance, impact strength, and tensile strength were examined. Comparative Example 7 In Example 1, the melting point was 260 ° C. instead of PVA-based fiber.
A molded article for measuring physical properties was obtained in the same manner as above except for using nylon fiber (13d × 1.5 mm), and the solvent resistance, impact strength and tensile strength were examined.

[0023]

Table 3 EO-PVA PVA fiber PVA fiber Melting temperatureContent (%) (℃) Example 1 (EO-1) (PVA-1) 6200〃2 (EO-2) (PVA-2) 3200〃3 (EO-3) (PVA-3) 17200〃4 (EO-4) (PVA-1) 0.5 190 〃 5 (EO-5) (PVA-2) 1.0 213６ 6 (EO-1) (PVA-3) 35 200 Comparative Example 1 (EO-1) -0 200 〃 2 (EO-1) (PVA-1) 60 200 〃 3 (EO-1) (PVA-5) 3 200 ４ 4 (EO-2) (PVA-6) ) 5 200 〃 5 (EO-5) (PVA-4) 10 205 ６ 6 (EO-1) (PVA-1) 6 215 〃 7 (EO-1) Nylon fiber 6 200(Nylon fiber content)  Table 4 shows the physical property measurement results of the examples and the comparative examples.

[0024]

TABLE 4 Solvent resistance (%) Impact strength Tensile strength Example Diameter Thickness (kg · mm / mm) (kg / mm ² ) 1 +1.9 +2.3 6.0 1.8 1.8 +1.4 +2. 0 8.5 2.0 3 +1.5 +1.9 5.8 1.7 4 +4.2 +5.1 4.7 1.5 5 +2.2 +2.4 4.6 1.6 1.6 +0.2 +0.1 13.5 4.2 Comparative Example 1 +8.0 +14.0 4.5 1.3 2 (Too much PVA fiber and poor moldability) 3 +7.9 +14.0 4.6 1.3 4 +7 6.0 +14.1 6.7 1.75 (Molding temperature is low and molding is not possible) 6 +7.0 +12.8 4.9 1.67 +8.0 +13.8 5.4 1.4

Note) Measurement method (impact strength) ・ JIS K 7110 (Izod impact test method) ・ Hammer lifting angle: 150 ° ・ Impact velocity: 3.5 m / s ・ Test piece: No. 2 test piece (quadrangular prism) (Tensile strength) Measured in accordance with JIS K 7113 ・ Test specimen shape: No. 6 dumbbell ・ Tensile speed: 5 mm / min ・ Measurement atmosphere: 20 ° C., 65 RH% (solvent resistance) diameter: 5 cm, wall thickness; A 3 cm disk-shaped compact was immersed in chloroform at room temperature for one month, the diameter and thickness immediately after removal were measured, the degree of swelling was examined, and the dimensional change was expressed in%.

[0026]

According to the present invention, the PVA-based resin molded product of the present invention is obtained by converting an oxyalkylene group-containing PVA-based resin having good melt moldability to PV
Because it is reinforced with A-based fiber, it has good compatibility and excellent resistance to solvents such as chloroform, methanol, and ethanol.
In addition, it has excellent mechanical strength and excellent enzyme barrier properties, and is very useful for various molded article applications.

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Claims (4)

(57) [Claims] 1. A saponification degree of 90 mol% or more, and an average degree of polymerization of 4
0.1 to 50 of 50 or more polyvinyl alcohol fibers
An oxyalkylene group-containing polyvinyl alcohol-based resin molded product characterized in that the molded product is contained by weight%. 2. The oxyalkylene group-containing polyvinyl alcohol-based resin molded product according to claim 1, wherein the melting point of the polyvinyl alcohol-based fiber is higher by at least 15 ° C. than the melting point of the oxyalkylene group-containing polyvinyl alcohol-based resin. 3. Saponification degree 90 mol% or more, average polymerization degree 4
0.1 to 50 of 50 or more polyvinyl alcohol fibers
A method for molding an oxyalkylene group-containing polyvinyl alcohol-based resin molded article, comprising molding a composition containing at least 10% by weight at a temperature lower than the melting point of the polyvinyl alcohol-based fiber by at least 10 ° C. 4. The molding of an oxyalkylene group-containing polyvinyl alcohol-based resin molded product according to claim 3, wherein the melting point of the polyvinyl alcohol-based fiber is higher than the melting point of the oxyalkylene group-containing polyvinyl alcohol-based resin by 15 ° C. or more. Law