JPH06226809A - Manufacture of plastic film - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a plastic film in which preferable film-forming properties are obtained and which has excellent warm water resistance even if emulsion containing polyvinyl alcohol resin and hydrophobic resin in which a content of the polyvinyl alcohol resin is reduced is used. CONSTITUTION:The method for manufacturing plastic film comprises the steps of extrusion molding emulsion containing high Tg hydrophobic resin (A) having a glass transition point or 45 deg.C or higher, low Tg hydrophobic resin (B) having a glass transition point of -10 deg.C or lower and polyvinyl alcohol resin (C) having saponification degree of 60-98mol% and having a solid content concentration of 60-85wt.% and then heat treating it at 150 deg.C or higher. A mixing ratio of the resin (A) with the resin (B) is set to 90:10-50:50 by weight, and a mixing ratio of the total amount of the resins (A) and (B) with the resin (C) is set to 90:10-70:30 by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a plastic film excellent in warm water resistance with good film-forming property from an emulsion containing a hydrophobic resin and a polyvinyl alcohol resin.

[0002]

2. Description of the Related Art Polyvinyl alcohol resins have excellent film-forming property, toughness, and solvent resistance,
In particular, its hot water resistance is inferior, so that its application range is limited.

Therefore, in order to make the most of the characteristics of the polyvinyl alcohol resin and to make up for its drawbacks, various plastic films prepared by mixing the polyvinyl alcohol resin with a hydrophobic emulsion (particularly polyvinyl chloride emulsion) have been proposed. ing.

For example, in JP-B-39-19030 and JP-B-41-19822, emulsion polymerization of vinyl chloride is carried out by using an aqueous polyvinyl alcohol solution as a dispersion medium and a catalyst and an emulsifier, and further adding polyvinyl to this emulsion. Alcohol is added so that polyvinyl alcohol accounts for 20 to 70% of the total resin content, and then the solubility in water is 1 if necessary.
% Or less of a plasticizer is added, water is evaporated from this solution to form a film, and heat treatment is performed at 150 to 230 ° C. for 10 seconds to 10 minutes to produce an unplasticized or unplasticized transparent polyvinyl chloride film. The law is shown.

In Japanese Patent Publication No. 43-1488, the film obtained in Japanese Patent Publication No. 39-19030 is stretched uniaxially by 3 times or more, and iodine or dichroic dye is drawn before or after the stretching. A method for producing a polarizing film by adsorbing a material that imparts a polarization property such as

JP-B-47-29579 discloses a vinyl chloride monomer and a vinyl acetate monomer in a molar ratio of 97: 3 to 6 in the presence of an emulsifier and a catalyst using an aqueous solution of a water-soluble polymer substance such as polyvinyl alcohol as a dispersion medium.
A vinyl chloride-vinyl acetate copolymer aqueous emulsion obtained by emulsion copolymerization at a ratio of 0:40 was further mixed with an aqueous polyvinyl alcohol solution as a matrix, and the weight ratio of polyvinyl alcohol and the vinyl chloride-vinyl acetate copolymer was 80: A method for producing a synthetic fiber or a film having excellent heat-sealing property, which is formed by mixing at a ratio of 20 to 30:70 at 40 ° C. to 65 ° C. and molding by a conventional method for producing a polyvinyl alcohol-based synthetic fiber or a polyvinyl alcohol-based film, It is shown.

JP-B-48-38468 discloses a polyvinyl alcohol sheet having excellent water resistance, which is obtained by blending polyvinyl alcohol with particles of a hydrophobic thermoplastic resin in an amount of 15% by weight or less with respect to polyvinyl alcohol. .

In Japanese Patent Publication No. 48-26947, 15 to 60 parts by weight of a polyhydric alcohol which is solid at room temperature and 100 parts by weight of a polyvinyl alcohol resin, and a latex or emulsion of a water-insoluble resin in terms of solid content are used. A polyvinyl alcohol-based resin molded product obtained by molding a composition prepared by mixing 1 to 20 parts by weight is shown. Here, the latex or emulsion of the water-insoluble resin is paraffin emulsion, polyethylene emulsion, wax emulsion, petroleum resin latex, rubber latex and the like.

[0009]

A film formed from an emulsion containing a polyvinyl alcohol-based resin and a hydrophobic resin retains the excellent film-forming property, toughness, and solvent resistance of the polyvinyl alcohol-based resin. However, there is a problem that the hot water resistance, which is a drawback thereof, is not necessarily improved.

In order to impart hot water resistance to the film, it is necessary to reduce the content of the polyvinyl alcohol-based resin, but if the content of the polyvinyl alcohol-based resin is reduced, then the film-forming property is impaired. Cause a situation.

Regarding the film forming method, when the casting method is adopted, it is general to set the solid content concentration to 20 to 30% by weight. In addition to requiring time, it is disadvantageous in terms of thermal energy, and a surface film is formed during drying, so that the film tends to be inhomogeneous. When the water-containing extrusion film-forming method is adopted, even if the hydrophobic resin emulsion and the polyvinyl alcohol-based resin are simply mixed, when the content of the polyvinyl alcohol-based resin is reduced, a slurry or gel is formed. However, there is a problem in that it is difficult to stably supply the stock solution to the molding machine.

Under such a background, the present invention provides a preferable film-forming property regardless of using an emulsion containing a polyvinyl alcohol-based resin and a hydrophobic resin and having a reduced content of the polyvinyl alcohol-based resin. It is an object of the present invention to provide a method for producing a plastics film which is excellent in hot water resistance.

[0013]

The method for producing a plastics film according to the present invention has a high Tg of 45 ° C. or higher.
A high Tg hydrophobic resin containing a hydrophobic resin (A), a low Tg hydrophobic resin (B) having a glass transition temperature of −10 ° C. or lower and a polyvinyl alcohol resin (C) having a saponification degree of 60 to 98 mol%.
The mixing ratio of (A) and low Tg hydrophobic resin (B) is 9 by weight.
It is 0:10 to 50:50, and the compounding ratio of the total amount of the high Tg hydrophobic resin (A) and the low Tg hydrophobic resin (B) and the polyvinyl alcohol resin (C) is 90:10 by weight. ~ 7
0:30, high Tg hydrophobic resin (A) and low Tg
The hydrophobic resin (B) is not an acrylic resin at the same time. After extrusion molding an emulsion having a solid content concentration of 60 to 85% by weight,
It is characterized by heat treatment at 0 ° C. or higher.

The present invention will be described in detail below.

In the present invention, the high Tg hydrophobic resin (A)
, An emulsion containing a low Tg hydrophobic resin (B) and a polyvinyl alcohol resin (C) is extruded, and then 1
Heat treatment is performed at 50 ° C. or higher.

The high Tg hydrophobic resin (A) means a hydrophobic resin having a glass transition point (Tg) of 45 ° C. or higher, preferably 60 ° C. or higher, such as polyvinyl chloride, polystyrene, polymethylmethacrylate, polyacrylonitrile, Styrene
Examples thereof include acrylonitrile copolymer.

The low Tg hydrophobic resin (B) means a hydrophobic resin having a glass transition point (Tg) of -10 ° C. or lower, such as acrylonitrile-butadiene copolymer (NBR) and methylmethacrylate-butadiene copolymer ( MBR), styrene-butadiene copolymer (SBR), polybutadiene (B
R), polyisoprene (IR), ethylene-vinyl acetate copolymer (EVA), methyl methacrylate-ethyl acrylate copolymer, methyl methacrylate-butyl acrylate copolymer, styrene-2-ethylhexyl acrylate copolymer, methyl methacrylate Examples include 2-ethylhexyl acrylate copolymer, vinyl acetate-2-ethylhexyl acrylate copolymer, vinyl acetate-butyl acrylate copolymer, and the like. However, since the glass transition point changes greatly depending on the copolymerization ratio,
A glass transition point of −10 ° C. or lower is used.

High Tg hydrophobic resin (A) and low Tg
At the same time, the hydrophobic resin (B) is required not to be an acrylic resin. This is because, in the case where both are acrylic resin, the present applicant has already filed Japanese Patent Application No. 3-290.
This is because the application was filed as No. 713.

The above-mentioned high Tg hydrophobic resin (A) and low Tg hydrophobic resin (B) are usually produced by an emulsion polymerization method. In emulsion polymerization, the polymerization is carried out in the presence of water, an emulsifier and a polymerization catalyst. As a result, an emulsion having a solid content concentration of about 40 to 60% by weight can be obtained. Therefore, if the polyvinyl alcohol-based resin (C) described below is blended in the form of powder, the solid content concentration will be 6%.
Emulsions of 0 to 85% by weight can be prepared without special concentration adjustment or with slight concentration adjustment.

As the polyvinyl alcohol resin (C), a polyvinyl alcohol resin having a saponification degree of 60 to 98 mol% is used. When the saponification degree is less than 60 mol%, the mechanical strength of the obtained film tends to be insufficient and the film tends to be deformed. On the other hand, when the degree of saponification exceeds 98 mol%, the miscibility with the hydrophobic resins (A) and (B) becomes poor, resulting in loss of transparency and formation of fish eyes. The degree of polymerization is not particularly limited, but in consideration of the mechanical strength and processability of the film, it is 400 to 2000.
It is often about 500 to 1800.

The polyvinyl alcohol resin (C) is
In addition to polyvinyl alcohol, which is a saponification product of vinyl acetate homopolymer, vinyl acetate and other comonomers (α-
Olefin, ethylenically unsaturated carboxylic acid or its salt, anhydride, ester, nitrile, amide, etc., ethylenically unsaturated sulfonic acid or its salt, vinyl ester other than vinyl acetate, alkyl vinyl ether, vinyl chloride,
“Vinylidene chloride, N-acrylamidomethyltrimethylammonium chloride, dimethyldiallyl vinyl ketone, N-vinylpyrrolidone, etc.”, a “copolymer-modified” polyvinyl alcohol which is a saponification product of the copolymer, or a polyvinyl alcohol or a copolymer-modified polyvinyl thereof. Urethane, urethane, acetal, etherification of alcohol,
It may be a “post-modified” polyvinyl alcohol that is post-modified by means such as acetoacetylation, sulfonation, cationization and the like.

High Tg hydrophobic resin (A) and low Tg hydrophobic resin
The mixing ratio with (B) is 90:10 to 50: 5 by weight.
It is set to 0, particularly 80:20 to 55:45.
Insufficient low Tg hydrophobic resin (B) impairs film-forming properties, resulting in low Tg
Too much hydrophobic resin (B) impairs the physical properties of the film.

High Tg hydrophobic resin (A) and low Tg hydrophobic resin
The total amount of (B) and the polyvinyl alcohol-based resin (C) is in a range in which the proportion of the polyvinyl alcohol-based resin (C) is relatively small, that is, 90:10 to 7 by weight.
Set within the range of 0:30. If the proportion of the polyvinyl alcohol-based resin (C) is too low, the film-forming property is impaired and problems such as cracking occur during drying, making it difficult to obtain a uniform film. On the other hand, if the proportion of the polyvinyl alcohol resin (C) is too large, the hot water resistance of the obtained film will be impaired.

An emulsion containing the above components is required to have a solid content of 60 to 85% by weight at the time of film formation. When the solid content is less than 60% by weight, it is difficult to take out the film when it is discharged from the die during extrusion film formation. On the other hand, when the solid content exceeds 85% by weight, the torque is increased during extrusion molding, and the film forming operation itself becomes difficult.

In addition to the above-mentioned components, additives such as a plasticizer (polyhydric alcohol), a filler, a surfactant, a colorant, an antioxidant, etc. can be added to the emulsion, if necessary.

The emulsion having the above composition is formed into a film by an extrusion molding method. The mixing of each component may be performed before feeding to the extruder or may be performed in the extruder. For example, a high Tg hydrophobic resin (A) emulsion, a low Tg hydrophobic resin (B) emulsion and a polyvinyl alcohol resin (C) powder are put into a kneader and premixed before being supplied to an extruder. Then, the polyvinyl alcohol resin (C) powder is supplied from the hopper of the extruder and a mixed emulsion of the high Tg hydrophobic resin (A) and the low Tg hydrophobic resin (B) is extruded. A method of injecting with a pump into the cylinder of the machine and extrusion molding is adopted. A method of removing unnecessary water by using an extruder with a vent at the time of compounding is also effective.

The temperature at the time of extrusion molding is such that the die temperature is 90 to 9
The cylinder temperature is often set to about 5 ° C. and the cylinder temperature is set to about 90 to 120 ° C., but not limited to this range.

After the extrusion molding, a water-containing film is used for 90 to 12
After drying at a temperature of about 0 ° C., heat treatment is performed at 150 ° C. or higher. The heat treatment operation is hot air supply method, hot roll contact method,
It can be performed by an infrared heating method or the like. When the heat treatment is omitted, or when the heat treatment temperature is less than 150 ° C. even if the heat treatment is performed, the hot water resistance of the obtained film becomes insufficient. The heat treatment operation may be either a method of providing a heat treatment zone after the drying zone to carry out the heat treatment step subsequent to the drying step, or a method of performing a separate heat treatment operation separately from the film formation-drying operation.

Depending on the purpose, stretching operations such as uniaxial stretching and biaxial stretching may be performed before or after the heat treatment or at the same time as the heat treatment. After the stretching operation, heat setting is usually performed.

The plastics film obtained by the above method may be further subjected to resin coating, laminating of a molten resin film, dry laminating of a resin film and the like.

The plastic film obtained by the method of the present invention is a film for PTP (press through pack) of pharmaceuticals, a film for synthetic paper, a film for general packaging, a film for belt production, a film for agriculture, a film for hygiene. It is useful for various applications such as a polarizing film.

Among them, in the case of a PTP film, this film or a laminated film with another resin is vacuum or pressure-formed to form an appropriate number of storage chambers, in which medicines such as tablets and capsules are stored. At the same time, aluminum foil is used as a backing material for sealing.

In the case of a film for synthetic paper, this film is biaxially stretched and again heat treated at 150 ° C. or higher. The stretching temperature is 100 to 175 ° C (preferably 120 to 130).
C.) and the draw ratio is often 1.5 to 2 times in the longitudinal and transverse directions. This stretching treatment can be performed before the above-mentioned heat treatment at the time of manufacturing the plastics film, and at that time, only one heat treatment is required.

The film for synthetic paper thus obtained does not require a solvent treatment as in the case of a stretched film of a conventional hydrophobic resin / polyvinyl alcohol resin melt blend (see Japanese Patent Publication No. 47-39936). In addition, it has a high degree of whitening and rigidity, and also has excellent hot water resistance. Further, the degree of whitening can be further increased by increasing the saponification degree of the polyvinyl alcohol-based resin to, for example, 95 mol% or more.

[0035]

In the present invention, a low Tg hydrophobic resin (B) is used in addition to the high Tg hydrophobic resin (A), and an extrusion molding is carried out using an emulsion containing a relatively small amount of polyvinyl alcohol resin (C). Film formation and heat treatment are performed. Therefore, preferable film-forming properties are obtained while the blending ratio of the polyvinyl alcohol resin (C) is relatively small, and the obtained film has excellent hot water resistance.

[0036]

EXAMPLES The present invention will be further described with reference to examples. Hereinafter, “parts” means parts by weight.

<Production of Film> Examples 1 to 10 Emulsions of high Tg hydrophobic resin (A) having a glass transition point of 45 ° C. or more (solid content 48 to
50% by weight), glass transition point -10 ° C or lower, low T
g Hydrophobic resin (B) emulsion (solid content 48-50% by weight) and polyvinyl alcohol resin (C) powder were stirred in a kneader at a temperature of 50 ° C. and then cooled to room temperature. As a result, a slightly bulky powder mixture without stickiness was obtained.

This mixed powder was fed to a twin-screw extruder, kneaded at a temperature of 100 ° C., discharged, cooled, and pelletized by a pelletizer. As a result, emulsions having solid content concentrations shown in Tables 1 and 2 ( Compound pellet) was obtained.

Next, the compound pellets were fed to a single-screw extruder equipped with a T-die and extrusion-molded under the following conditions to obtain a translucent hydrous film. -Extruder: Single screw extruder with a diameter of 40 mm and L / D = 28-Die: coat hanger type-Screw: full flight type, compression ratio 3-Die temperature: 95 ° C-Cylinder temperature: 100-115 ° C-Lip clearance : 0.5mm

This film was dried at 100 to 120 ° C. and then heat treated at the heat treatment temperatures shown in Tables 1 and 2 for 2 minutes. As a result, a target film having a thickness of about 200 μm was obtained.

Comparative Examples 1 to 9 In accordance with Examples 1 to 10, experiments were conducted for cases outside the range specified in the present application.

<Conditions and Results> The film forming properties during extrusion molding in Examples 1 to 10 and Comparative Examples 1 to 9 were observed, and the hot water resistance of the obtained target film was measured. The conditions (formulation formulation, emulsion concentration, heat treatment temperature) and evaluation results are shown in Tables 1 to 3.

[0043]

[Table 1] Formulation Concentration Heat treatment Film- forming property Elution rate Example 1 (A) PVC with Tg 80 ° C 49 parts 70% 175 ° C ○ 0.2% (B) EVA with Tg -11 ° C 21 parts (C) SV88, P1700 PVA 30 parts Example 2 (A) PVC with Tg 80 ° C 48 parts 80% 200 ° C ○ 0.15% (B) Tg -11 ° C EVA 32 parts (C) SV88, P1700 PVA 20 parts Example 3 (A) Tg 80 ° C PVC 52.5 parts 70% 175 ℃ ○ 0.1% (B) Tg -11 ℃ EVA 22.5 parts (C) SV80, P1700 PVA 25 parts

[0044]

[Table 2] Formulation Concentration Heat treatment Film formability Elution rate Example 4 (A) PVC with Tg 80 ℃ 55 parts 70% 220 ℃ ○ 0.3% (B) EVA with Tg -11 ℃ 30 parts (C) SV96, P1700 PVA 25 parts Example 5 (A) Tg 80 ° C PVC 55 parts 70% 200 ° C ○ 0.1% (B) Tg -55 ° C NBR ₁ 30 parts (C) SV88, P1700 PVA 15 parts Example 6 (A) Tg 80 PVC 52.5 parts 70% 200 ℃ ○ 0.2% (B) Tg -24 ℃ NBR ₂ 22.5 parts (C) SV80, P1700 PVA 25 parts Example 7 (A) Tg 100 ℃ PSt 52.5 parts 70% 150 ℃ ○ 0.3% (B) Tg -11 ℃ EVA 22.5 parts (C) SV80, P1700 PVA 25 parts Example 8 (A) Tg 100 ℃ PSt 52.5 parts 70% 200 ℃ ○ 0.1% (B) Tg- 57 ° C SBR 22.5 parts (C) SV96, P1700 PVA 25 parts Example 9 (A) Tg 105 ° C PMMA 52.5 parts 70% 150 ° C 0.1% (B) Tg -11 ° C EVA 22.5 parts (C) SV70, P1700 PVA 25 parts Example 10 (A) Tg 105 ℃ PMMA 52.5 parts 70% 200 ℃ ○ 0.1% (B) Tg -57 ℃ SBR 22.5 parts (C) SV88, P1700 PVA 25 parts

[0045]

[Table 3] Compounding recipe Concentration Heat treatment Film- forming property Elution rate Comparative Example 1 (X) Tg 30 ° C PVAc 49 parts 70% 175 ° C △ ^{* 1} 8% (Y) Tg -11 ° C EVA 21 parts (Z) SV88, P1700 PVA 30 parts Comparative Example 2 (X) Tg 80 ° C PVC 49 parts 70% 175 ° C △ ^{* 1} 3% (Y) Tg -5 ° C MMA / EA 21 parts (Z) SV88, P1700 PVA 30 parts Comparative Example 3 (X) Tg 80 ° C PVC 49 parts 70% 175 ° C △ ^{* 1} 3% (Y) Tg -11 ° C EVA 21 parts (Z) SV50, P500 PVA 30 parts Comparative Example 4 (X) Tg 80 ° C PVC 49 parts 70% 175 ℃ △ ^{* 1} 10% (Y) Tg -11 ℃ EVA 21 parts (Z) SV99.5, P500 PVA 30 parts Comparative Example 5 (X) Tg 80 ℃ PVC 49 parts 50 % − × ^{* 2} − ^{* 4} (Y) Tg -11 ° C EVA 21 parts (Z) SV88, P1700 PVA 30 parts Comparative Example 6 (X) Tg 80 ° C PVC 49 parts 90% − × ^{* 3} − ^{* 4} (Y) Tg -11 ℃ EVA 21 parts (Z) SV88, P1700 PVA 30 parts Comparative Example 7 (X) Tg 80 ℃ PVC 49 parts 70% 135 ℃ ○ 50% (Y) Tg -11 ℃ EVA 21 parts (Z) SV88, PVA 30 parts PVA 30 parts Comparative Example 8 (X) Tg 80 ° C PVC 70 parts 70% − × ^{* 2} − ^{* 4} (Y) Tg −11 ° C EVA 30 parts Comparative Example 9 ( X) Tg 80 ° C PVC 70 parts 70% − × ^{* 2} − ^{* 4} (Z) SV88, P1700 PVA 30 parts

(Note) ・ PVC is polyvinyl chloride, PSt is polystyrene, PMMA
Is polymethylmethacrylate, PVAc is polyvinyl acetate. EVA is an ethylene-vinyl acetate copolymer with an ethylene content of 28% by weight, NBR ₁ is an acrylonitrile-butadiene copolymer with a butadiene content of 70% by weight, and NBR ₂ is a butadiene content.
50 wt% acrylonitrile-butadiene copolymer, SB
R is a styrene-butadiene copolymer having a butadiene content of 75% by weight, and MMA / EA is a methylmethacrylate-ethylacrylate copolymer having an ethyl acrylate content of 78% by weight.・ PVA is polyvinyl alcohol, SV is saponification degree (mol%), P is polymerization degree. -The concentration is the solid content concentration (% by weight) of the emulsion. -The heat treatment is the heat treatment temperature. The film-forming property was judged according to the following criteria from the discharge state at the time of extrusion molding, the removability, and the appearance of the film. ◯: Film forming property is good Δ: Film forming is possible, but moldability and film state are poor ×: Poor ejection, no film forming power ・ Elution rate is 200 cc at 40 mm square after heat treatment,
Dissolution rate based on the following calculation formula after immersion in pure water at 60 ° C for 1 hour (food packaging hygiene test, Ministry of Health and Welfare Notification No. 20 of 1982)
According to the section of the dissolution rate of No.). Dissolution rate (%) = 100 x eluate weight / film weight before immersion ・ Meaning of ^{* n} in the column of film formability and dissolution rate in Comparative Example is as follows. ^{* 1} : Molding failure, ^{* 2} : No film formation, ^{* 3} : Torque increased and molding was not possible, ^{* 4} : Measurement not possible.

<Production of Film for Synthetic Paper> Example 11 According to Examples 1 to 10, 60 parts of PSt (A) at Tg of 100 ° C., Tg
20 parts of EVA (B) at -11 ° C, SV 95 mol%, degree of polymerization 5
A water-containing film was prepared with a formulation of 20 parts of PVA of 00 and then dried at 100 to 120 ° C. to obtain a film having a thickness of about 200 μm. This film is fed to a tenter and the temperature is 130 ° C.
After stretching 1.5 times in the machine and transverse directions, heat treatment was performed at 200 ° C. to obtain a film for synthetic paper.

Comparative Example 10 According to Examples 1 to 10, 80 parts of PSt (X) with Tg of 100 ° C. and SV
95 mol%, 20 parts of PVA with a degree of polymerization of 500, and glycerin
A water-containing film was produced with the formulation of 2 parts (molding is impossible without glycerin), and then dried at 100 to 120 ° C. to obtain a film having a thickness of about 200 μm. This film was supplied to a tenter, stretched at a temperature of 130 ° C. in the longitudinal and transverse directions by 1.5 times each, and then heat treated at 200 ° C. to obtain a film for synthetic paper.

<Results> With respect to the synthetic paper films obtained in Example 11 and Comparative Example 10, the elution rate, white light transmittance and discharge half-life were measured by the following methods. The results are shown in Table 4.・ Elution rate ・ White light transmittance 100% when film is not passed through using a photoelectric colorimeter
The value measured as. The smaller this value, the greater the degree of whitening of the film.・ Discharge half-life 48 hours under the condition of temperature 20 ℃ and relative humidity 65%.
The sample is allowed to stand for a period of time to control the humidity, and a static voltage of 8000 V is applied from 1.5 cm above the film using a static Honest meter manufactured by Shishido Co., Ltd., and the static voltage induced in the sample film decreases with time. The state was automatically recorded and the time until the first induced electrostatic voltage was reduced to half was taken as the discharge half-life.

[0050]

[Table 4]  Dissolution rate (%) Transmission rate (%) Half-life (sec) Example 11 0.1 7 15 Comparative Example 10 30 20 15

[0051]

INDUSTRIAL APPLICABILITY As described in the section of the action, in the present invention, in addition to the high Tg hydrophobic resin (A), the low Tg hydrophobic resin is used.
Since (B) is used, polyvinyl alcohol resin
Despite the relatively small content of (C), favorable film-forming properties were obtained, and the resulting film had excellent hot water resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29L 7:00 4F

Claims (2)

[Claims] 1. A high Tg hydrophobic resin (A) having a glass transition point of 45 ° C. or higher and a low Tg hydrophobic resin having a glass transition point of −10 ° C. or lower.
(B) and a polyvinyl alcohol-based resin (C) having a saponification degree of 60 to 98 mol%, a high Tg hydrophobic resin (A) and a low T
The mixing ratio with the hydrophobic resin (B) is 90:10 by weight.
50:50, total amount of high Tg hydrophobic resin (A) and low Tg hydrophobic resin (B), and polyvinyl alcohol resin
The compounding ratio with (C) is 90:10 to 70:30 by weight, and the high Tg hydrophobic resin (A) and the low Tg hydrophobic resin
(B) is not an acrylic resin at the same time Solid content concentration 60 to 8
A method for producing a plastics film, which comprises subjecting an emulsion of 5% by weight to extrusion molding and then heat-treating at 150 ° C. or higher. 2. The method according to claim 1, wherein the plastics film is a plastics film for synthetic paper.