JP2528052B2 - Molded product manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a composite fiber, a film, and other molded products obtained by blending a hydrophobic resin with a specific resin capable of imparting antistatic property and hydrophilicity and melt-molding the resin. The present invention relates to a method of manufacturing.

[0002]

2. Description of the Related Art Modification of a sulfonic acid group-containing hydrophobic resin such as polyethylene, polypropylene, polyvinyl chloride, nylon, polystyrene, polyamide, and polyester for imparting antistatic property and hydrophobicity or improving moldability. Attempts have been made to blend polyvinyl alcohol (hereinafter abbreviated as PVA) into a hydrophobic resin using the hydrophilicity-imparting agent.

Conventionally, as such modified PVA, a saponified copolymer obtained by copolymerizing (meth) allylsulfonic acid (sodium) and vinyl acetate has been used.

[0004]

However, since a resin having a high degree of polymerization cannot be obtained by such modification with allyl sulfonic acids, when the modified PVA is used, the mechanical strength of the obtained molded article decreases. In addition, there was a tendency that undissolved substances such as fish eyes were generated in the molded product to a considerable extent.

Under the circumstances, the present invention is capable of imparting antistatic property and hydrophilicity to a hydrophobic resin, and also has excellent mechanical properties and undissolved substances such as fish eyes. It is an object of the present invention to provide a method for producing a molded product in which the occurrence of

[0006]

The method for producing a molded article of the present invention comprises a sulfonic acid obtained by copolymerizing an N-sulfoalkyl (meth) acrylamide represented by the formula (1) with vinyl acetate and then saponifying it. Group containing 0.1 to 20 mol%, average saponification degree 10 to 99.9 mol%, 4% by weight at 20 ° C
It is characterized in that a resin composition having a weight ratio of a sulfonic acid group-containing modified polyvinyl alcohol having a viscosity of an aqueous solution of 5 centipoise or more and a hydrophobic resin is 5:95 to 95: 5 is melt-molded.

[0007]

Embedded image (R ₁ ; hydrogen or methyl group, R ₂ ; alkylene group, M;
Hydrogen or alkali metal)

The present invention will be described in detail below.

The first component of the resin composition used in the present invention is
As described above, it is a sulfonic acid group-containing modified PVA obtained by copolymerizing N-sulfoalkyl (meth) acrylamide and vinyl acetate and then saponifying the same. Alkylene group (R in N-sulfoalkyl (meth) acrylamide
Examples of ₂ ) include an ethylene group, a propylene group, a butylene group and the like, and these may be linear or branched, but from the viewpoint of stability during saponification of the copolymer, a branched alkylene group is preferable. Is preferred. Further, M is hydrogen or an alkali metal, but since a free sulfonic acid (M is hydrogen) may decompose vinyl acetate during copolymerization, an alkali metal such as sodium or potassium is usually desirable. Among such acrylamides, N-sulfoisobutylene acrylamide sodium salt represented by the formula (2) is particularly preferable for the purpose of the present invention.

[0010]

Embedded image

In producing the above-mentioned modified PVA, first, N-sulfoalkyl (meth) acrylamide and vinyl acetate are copolymerized in an alcohol solvent. At this time, the amount of alcohol used is 5 relative to the weight of vinyl acetate so that the modified PVA has a viscosity of 5 centipoise or more.
It is necessary to regulate it to 0% or less. The viscosity is measured with a 4 wt% aqueous solution at a temperature of 20 ° C. using a B-type rotational viscometer.

As the alcohol, lower alcohols such as methanol, ethanol and propanol are usually used. These alcohols may contain a small amount of water. There are no particular restrictions on the method of charging the monomers during the polymerization, and any method such as batch charging, divided charging, continuous charging may be adopted, but N-sulfoalkyl (meth)
From the viewpoint of the copolymerization ratio of acrylamide and vinyl acetate, it is advantageous to first dissolve vinyl acetate in an alcohol solvent and polymerize while adding the above (meth) acrylamide dropwise thereto because a copolymer having a uniform composition is easily obtained. Is. As a catalyst for the copolymerization, known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, lauroyl peroxide and the like are used. Usually, the polymerization temperature is preferably about 50 ° C to the boiling point.

In carrying out such polymerization, in addition to the above-mentioned two components, other unsaturated monomer copolymerizable with such a monomer, for example, styrene, alkyl vinyl ether,
(Meth) acrylamide, ethylene, propylene, α-
An olefin such as hexene or α-octene, an unsaturated acid such as (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid, or an alkyl ester or alkali salt thereof is present in an amount of about 10 mol% or less. It is also possible. The copolymer thus polymerized is saponified according to a conventional method.

Upon saponification, the copolymer is dissolved in alcohol or hydrous alcohol and saponified with acid or alkali. Examples of alcohol include methanol, ethanol, propanol and the like, and methanol is preferably used. The concentration of the copolymer in alcohol is usually selected from the range of 20 to 70% by weight. Examples of the saponification catalyst include hydroxides of alkali metals such as potassium hydroxide, sodium hydroxide, sodium methylate, sodium ethylate and potassium methylate, alkali catalysts such as alcoholate, and acid catalysts such as sulfuric acid and hydrochloric acid. Is used. The appropriate amount of such a catalyst is usually 0.1 to 5.0 mol% with respect to vinyl acetate. The temperature during the saponification reaction is not particularly limited, but is usually selected in the range of 10 to 50 ° C, preferably 20 to 40 ° C. Saponification reaction is 0.1
~ 5 hours.

The modified PVA obtained above has a sulfonic acid group content of 0.1 to 20 mol% and an average saponification degree of 10
A high polymerization degree sulfonic acid group-containing modified PVA having a viscosity of 5 to 99.9 mol% and a 4 wt% aqueous solution at 20 ° C. of 5 centipoises or more, particularly preferably 10 centipoises or more. When the sulfonic acid group content is less than 0.1 mol%, the antistatic property and hydrophilicity imparting effect on the hydrophobic resin are lacking.
If it exceeds 0 mol%, the modified PVA will have a low degree of polymerization and the mechanical properties of the resin composition will deteriorate. Also, 20
When the viscosity of the 4 wt% aqueous solution at 0 ° C. is less than 5 centipoise, the effect of the present invention cannot be obtained at all.

The second component of the resin composition used in the present invention is a hydrophobic resin. Here, as the hydrophobic resin, for example, polyethylene, polypropylene, polyvinyl chloride,
Examples thereof include polyester, polystyrene, poly-P-xylene, nylon, polyacrylate, polymethacrylate, polyacrylonitrile, and polyvinylidene chloride.

The mixing ratio of the hydrophobic resin and the modified polyvinyl alcohol containing a sulfonic acid group is 95: 5 by weight.
It is 5:95, especially 90:10 to 70:30. If the proportion of the latter is too small, the antistatic property and hydrophilicity-imparting effect are insufficient, while if the proportion of the latter is too large, the mechanical properties of the molded product are impaired.

The resin composition is molded according to a known melt molding method such as an extrusion molding method or an injection molding method to obtain a composite fiber, a film or other molded article.

[0019]

The molded product obtained by the method of the present invention has a high degree of polymerization of the sulfonic acid group-containing modified PVA in the resin composition and is highly hydrophilic and water-soluble. Mechanical properties are better than that of the above, and undissolved substances such as fish eyes are unlikely to occur in the molded product.

[0020]

EXAMPLES The present invention will be described in more detail below with reference to examples. The terms "part" and "%" are based on weight unless otherwise specified.

Examples 1 to 4 A polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer and a stirrer was charged with 834 parts of vinyl acetate and 158 parts of methanol.
The temperature was raised with stirring, and a solution of 0.30 parts of azobisisobutyronitrile dissolved in 50 parts of methanol was added at 60 ° C. to initiate polymerization. From the start of the polymerization, the polymerization was continued while dropping 196 parts of a 23% methanol solution in which 46 parts of N-sulfoisobutylene acrylamide sodium salt was dissolved. After 5 hours, the polymerization rate is 6
The polymerization was stopped when it reached 0%. The obtained copolymer solution was purified by a conventional method to obtain an N-sulfoisobutylene acrylamide sodium salt-vinyl acetate copolymer.

A 30% methanol solution of the copolymer was prepared, and a saponification reaction was carried out in a kneader at 40 ° C. by adding a methanol solution of 20 mmol of sodium hydroxide to vinyl acetate groups. The produced modified PVA was separated by filtration, washed, and dried to obtain the desired product. The characteristic values of the obtained sulfonic acid group-containing modified PVA were as follows.

Sulfonic acid group content: 3.0 mol%, average saponification degree: 94.9 mol%, 4% aqueous solution viscosity at 20 ° C .: 30.5 centipoise IR (cm ⁻¹ ) 1660 and 1540 (second Amido group) 1040 and 630 (sulfonic acid group) NMR (δ ppm) 1.7 (attributed to -CH ₃ ).

From the above, the amide bond is not cleaved by saponification of the copolymer, and the presence of a sulfonic acid group is confirmed.

The N-sulfoisobutylene acrylamide sodium salt-modified PVA obtained above and low density polyethylene were mixed at a predetermined ratio, and the mixture was heated at 200 to 210 ° C. for T.
A 30 μm film was produced by the die melt extrusion method.

Comparative Examples 1-2 Sodium allyl sulfonate modified PV as modified PVA
An experiment was conducted in the same manner as in Examples 1 to 4 except that A was used.

<Results> Table 1 shows the measurement results of Examples 1 to 4 and Control Examples 1 and 2 together. For the viscosity of the 4% aqueous solution, the viscosity of the 4% aqueous solution at 20 ° C. was measured using a B type rotational viscometer.
The characteristic value of the film was measured by Shimadzu Autograph IM-1100 model under the conditions of 65% RH and 20 ° C. Table 1
The modified PVA used in Comparative Examples 1 and 2 was allylsulfo.
It is sodium phosphate modified PVA.

[0028]

[Table 1]

Examples 5 to 8 N-sulfoisobutylene acrylamide sodium salt-modified PVA (modification amount 2.9 mol%, saponification degree 88.2 mol%, 4% aqueous solution viscosity 5.9 centipoise) was used for the modification. PVA made of rigid polyvinyl chloride (Examples 5 and 6)
Alternatively, it was mixed with nylon 12 (Examples 7 and 8) and melt-molded to obtain a 100 μm film.
The physical properties of this film are shown in Table 2. It can be seen from Table 2 that the mechanical properties of the hydrophobic PVA are not deteriorated by the compounding of the modified PVA as compared with the case of using the hydrophobic resin alone.

[0030]

[Table 2] Hydrophobic resin type Hydrophobic resin / modified film physical properties PVA mixing ratio Tensile strength Elongation (weight ratio) (kg / cm ² ) (%) Example 5 Rigid polyvinyl chloride 90: 10 483 10 Example 6 Hard polychlorination Vinyl 80: 20 479 9 Example 7 Nylon 12 90: 10 435 218 Example 8 Nylon 12 80: 20 427 205

[0031]

[Effect] As described in the section of action, the molded product obtained by the method of the present invention has a high degree of polymerization of the sulfonic acid group-containing modified PVA in the resin composition, and is also highly hydrophilic and water-soluble. The mechanical properties of the PVA are better than those of conventional PVA modified with allyl sulfonic acids, and undissolved substances such as fish eyes are less likely to occur in the molded product.

Claims (1)

(57) [Claims] 1. A formula (1) N-sulfoalkyl represented by (meth) acrylamide copolymerized with vinyl acetate, with
In saponification to sulfonic acid group-containing 0.1 to 20 mol% obtained, the average saponification degree 10 to 99.9 mol%, viscosity of 4% by weight aqueous solution at 20 ° C. is not less than 5 centipoise sulfonic acid group-containing modified polyvinyl the alcohol and the hydrophobic resin
5: 95-95: 5 resin composition by melt molding
A method for producing a molded article, comprising: Embedded image (R ₁ ; hydrogen or methyl group, R ₂ ; alkylene group, M;
Hydrogen or alkali metal)