JP2002256029A - Vinylidene chloride-based copolymer particle and extrusion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinylidene chloride-based copolymer particle having a specific particle size distribution and a bulk specific gravity, a copolymer particle which can improve the extrusion characteristics such as an extrusion stability and an uniform film thickness for obtaining an oriented or non-oriented film, a single layer material or a multilayer material by an ordinary melt molding method and an obtained film. SOLUTION: The vinylidene chloride-based copolymer particle is characterized by having a weight average particle size of 200-500 μm and a content of a particle, of which the particle size is less than 150 μm, or 3 wt.% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vinylidene chloride-based copolymer particles, an extrusion method using the same, and a food packaging film obtained from the copolymer particles.

[0002]

2. Description of the Related Art Generally, a suspension polymerization method and an emulsion polymerization method are used for producing a vinylidene chloride-based copolymer. The suspension polymerization method is a method in which mixed and dispersed oil droplets of vinylidene chloride and a polymerizable vinyl monomer are formed by mechanical stirring in water containing a dispersant, and polymerization is performed using a polymerization initiator. The emulsion polymerization method is a method in which vinylidene chloride and a polymerizable vinyl monomer are polymerized in a surfactant micelle using a water-soluble polymerization initiator.

[0003] Among them, when a film for food packaging is obtained from a vinylidene chloride copolymer having poor heat stability by, for example, an extrusion method, the vinylidene chloride copolymer obtained by emulsion polymerization is used. The use of coalescing is not suitable because thermal degradation due to the remaining emulsifier is likely to occur. Therefore, a vinylidene chloride copolymer obtained by suspension polymerization is generally used. When a food packaging film is to be obtained, the vinylidene chloride copolymer obtained by suspension polymerization is processed into a stretched or unstretched, monolayer or multilayer structure film by a usual melt molding method. Is done.

In general, it is known that a vinylidene chloride copolymer obtained by suspension polymerization is in the form of particles. It is also known that the obtained copolymer particles can only be obtained with a wide particle size distribution. For example, Japanese Patent Publication No. 55-18242 and Japanese Patent Publication No. 57-9575 show specific examples of spherical particles of vinylidene chloride-based copolymer by scanning electron micrograph. However, there is no description about the characteristics of the particles such as the particle size, the particle size distribution and the bulk specific gravity.

[0005] Further, in the extrusion method, the shape of the copolymer is disclosed in Japanese Patent Publication Nos. 3-500181 and 3-500.
No. 662 discloses that extrusion characteristics are improved by extruding vinylidene chloride-based copolymer particles together with an extrusion aid into pellets suitable for an extrusion method. In general, as a method of supplying a raw material to an extruder, a method in which a raw material is charged into a supply unit in a granular form, a method in which a raw material is supplied using a table feeder or a screw feeder, and the like are known. However, it is known that the supply accuracy of these raw material supply methods directly affects the extrusion accuracy of an extruder, and causes a variation in the discharge amount over time.

[0006] This also suggests that the shape of the vinylidene chloride-based copolymer affects the discharge fluctuation of the extruder and affects the extrusion processing characteristics. When it is difficult to supply a stable raw material into the extruder of vinylidene chloride-based copolymer particles, the amount of the raw material charged into the barrel from inside the die fluctuates, and this causes fluctuation in head pressure. Arouses fluctuations in film thickness and discharge rate of extruded products, and reduces uniform film thickness of film products.

[0007] When a film having a non-uniform film thickness is used, the sealing property at the time of food packaging is deteriorated, which leads to a reduction in the yield during production. In order to solve the above-mentioned problems, in order to supply a certain amount of raw material into the extruder, a method of improving the distribution of the copolymer particles of the raw material to a state in which the raw material can be stably supplied and a method of controlling the accuracy of the supply method to the extruder Have been tried. However, the relationship with the optimal range of the particle size that can stably extrude the vinylidene chloride-based copolymer particles as the raw material, for example, the feed stability of the copolymer particles, the load condition and stability of the extruder, and There is no description in the conventional literature about the improvement with respect to the uniformity of the film thickness of the film to be processed.

Further, it has not been explicitly disclosed that the extrusion processing characteristics can be improved by selecting the weight average particle size and distribution of the vinylidene chloride-based copolymer particles. Accordingly, it is expected to provide vinylidene chloride-based copolymer particles having excellent stable extrusion characteristics and excellent film thickness uniformity.

[0009]

SUMMARY OF THE INVENTION The present invention provides vinylidene chloride-based copolymer particles having a specific particle size, a ratio of fine particles, and a specific gravity, and is prepared by a conventional melt molding method. When used as a single-layer or multilayer structure film, it has excellent stable extrusion properties,
It is another object of the present invention to provide a copolymer particle having excellent uniformity in film thickness, a film obtained therefrom, and a method for producing the film.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventor has proposed that vinylidene chloride-based copolymer particles having a specific range of particle size distribution obtained from suspension polymerization are prepared by a conventional melt molding method. Thus, it is found that when stretched or unstretched, when a film having a single-layer structure or a multilayer structure is formed, it is excellent in stable extrusion processing characteristics, and it is possible to further improve the above characteristics, and to form the present invention. Reached.

That is, the present invention is as follows. 1) The weight average particle diameter is in the range of 200 to 500 μm, and the ratio of particles having a particle diameter of less than 150 μm is 3 w
vinylidene chloride-based copolymer particles having a content of at most t%. 2) The bulk specific gravity of the vinylidene chloride copolymer particles is
^{0.80g / cm 3 ~1.0g / cm 3} 1 , characterized in that a) vinylidene chloride copolymer particles according.

3) The vinylidene chloride-based copolymer is selected from vinylidene chloride and a polymerizable vinyl monomer.
The copolymer particles according to 1) or 2), which are obtained by copolymerization with at least one kind of monomer. 4) The polymerizable vinyl monomer is at least one selected from the group consisting of vinyl chloride, methyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, acrylonitrile, and styrene. The copolymer particles according to the above.

5) The vinylidene chloride-based copolymer particles described in any one of 1) to 4) above are extruded by an extruder equipped with a weight feeder capable of performing quantitative supply. Extrusion processing method. 6) An extrusion method, wherein the vinylidene chloride-based copolymer particles according to any one of 1) to 4) are extruded by an extruder capable of controlling a degree of vacuum. 7) A film obtained from the vinylidene chloride-based copolymer particles according to any one of 1) to 4).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The vinylidene chloride copolymer of the present invention is obtained from a vinylidene chloride monomer and a vinyl monomer copolymerizable with the vinylidene chloride monomer. Examples of vinyl monomers copolymerizable with vinylidene chloride include vinyl esters such as vinyl chloride, vinyl acetate and vinyl propionate, for example, methyl acrylate, ethyl acrylate, butyl acrylate,
-Ethylhexyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, phenyl acrylate, cyclohexyl acrylate,

Glycidyl acrylate and methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, glycidyl methacrylate and other α, β unsaturated carboxylic esters, ethylene and propylene, etc. Examples include olefins, lauryl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, and vinyl ethers such as isobutyl vinyl ether.

Also, copolymerizable materials such as itaconic acid, maleic acid, maleic anhydride, acrylonitrile, methacrylonitrile, styrene, methylstyrene, α-methylstyrene, chlorostyrene, chloromethylstyrene and the like are mentioned. The polymerizable vinyl monomers may be used alone or in a mixture of two or more. Among them, vinyl chloride, methyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, acrylonitrile, and styrene are more preferable.

The polymerization initiator used in the present invention includes, for example, diisopropyl peroxydicarbonate, dioctyl peroxydicarbonate, dilauryl peroxydicarbonate, dimyristyl peroxydicarbonate, dicetyl peroxydicarbonate, ditertium Shaributyl peroxydicarbonate, di (ethoxyethyl) peroxydicarbonate, di (methoxyisopropyl) peroxydicarbonate,

Di (3methoxybutyl) peroxydicarbonate, di (3methoxy-3-methylbutyl) peroxydicarbonate, di (butoxyethyl) peroxydicarbonate, di (2isopropoxyethyl) peroxydicarbonate, Start of percarbonate systems such as di (2-ethylhexyl) peroxydicarbonate, di (2-isopropoxyethyl) peroxydicarbonate, dibenzylperoxydicarbonate, dicyclohexylperoxydicarbonate, ditertiarybutylcyclohexylperoxydicarbonate, etc. Agent,

Tertiary butyl peroxy neodecanoate, tertiary hexyl peroxy neo decanoate, amyl peroxy neo decanoate, tertiary octyl peroxy neo decanoate, α-cumyl peroxy neo decanoate, 1-cyclohexyl -1-methylethyl peroxy neodecaneate, tertiary butyl peroxypivalate, amyl peroxypivalate, tertiary octyl peroxypivalate, tertiary hexyl peroxypivalate, α-cumylperoxypivalate, per Hexyl oxalate, ditertiary butyl peroxy oxalate, acetylcyclohexylsulfonyl peroxide, 1.1.3.3.
Perester initiators such as tetramethylbutyl peroxyphenoxyacetate,

Diacyl peroxide based initiators such as lauroyl peroxide, diisobutyl peroxide, 2-ethylhexanoyl peroxide, 3.5.5 trimethylhexanoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide Benzoyl peroxide, di-isopropylperoxy dicarbonate, t-butylperoxyisobutyrate,
di-t-alkyl peroxydiglycolate initiators such as t-hexylperoxydiglycolate,

2.2 'azobisisobutyronitrile,
2.2 'azobis-2.4 dimethylvaleronitrile,
2.2 'azobis-4methoxy-2.4 dimethylvaleronitrile, 4,4-azobis (4-cyanopentanoic acid)
Azo-based initiators such as 2.2'-azobis (2-amidinopropane) hydrochloride and 2.2'-azobis (NN'-dimethyleneisobutylamidine) hydrochloride, and aqueous solutions such as potassium persulfate and ammonium persulfate Or a system in which a reducing agent such as an amine or sodium bisulfite is added thereto.

These are used in order to make the polymerization reaction rate uniform.
Two or more polymerization initiators having different 0 hour half-lives may be used in combination. These polymerization initiators may be used as they are, may be used as a water emulsion or a water suspension, or may be used after being dissolved in a solvent such as toluene. The amount of the initiator used is preferably 100 to 7000 ppm, more preferably 500 to 5000 ppm, based on the vinylidene chloride-based monomer mixture.
More preferably, it is 1000 to 3000 ppm.

In order to obtain vinylidene chloride copolymer particles having a weight average particle diameter of 200 to 500 μm and a specific gravity in a specific range, a suspension polymerization method is preferred. In the present invention, as the suspending / dispersing agent, homopolymers such as polyvinylpyrrolidone, polyacrylic acid, polyvinyl alcohol, polymethylvinylether, polyacrylamide, polyethyleneimine, poly (2-ethyl-2-oxazoline), and maleic anhydride- Synthetic polymers such as vinyl acetate copolymers and various random copolymers, graft copolymers, block copolymers, macromonomers, etc .; water-soluble cellulose derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose; starch, gelatin, etc. Natural polymer substances and the like can be used. If desired, an auxiliary stabilizer can be used in addition to the above-mentioned dispersion stabilizer.

Examples of such co-stabilizers include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants and long-chain alcohols. Among these suspending and dispersing agents, methyl cellulose, hydroxypropyl cellulose and hydroxypropoxymethyl cellulose are particularly preferred. These are 0.
The surface tension of the 2 wt% aqueous solution at 20 ° C. is preferably 5 mN / m or more from the viewpoint of the particle size to be obtained, and is preferably 60 mN / m or less from the viewpoint of polymerization progression.

The total amount of the suspending and dispersing agent is 30 parts with respect to the vinylidene chloride monomer from the viewpoint of the stability of suspension polymerization.
ppm or more is preferable, and from the viewpoint of the obtained particle diameter,
It is preferably at most 000 ppm. More preferably 100 to
5,000 ppm, more preferably 200 to 3,000 ppm
It is 0 ppm. With such a range, suspension stability is obtained, and the desired weight average particle diameter of 200 to
500 μm can be obtained, and fine particles having a particle diameter of less than 150 μm can be reduced.

The suspension dispersant used in the suspension polymerization may be added all at once or in portions, and the timing of addition is not limited. Further, if the slurry pH of the vinylidene chloride-based copolymer is too low, the corrosion rate in the polymerization machine and in the subsequent process equipment increases, so that such a problem in the polymerization system is avoided as much as possible. In order to adjust the pH at the beginning or during the polymerization, an alkaline substance may be added to a necessary minimum.

The suspension polymerization reaction of the vinylidene chloride-based monomer is carried out in such a manner that the vinylidene chloride-based monomer, water and the suspending dispersant are charged in a polymerization machine, and almost all of the prescribed amounts are charged and stirred. The process is started after the formation of vinylidene monomer droplets. Further, in order to improve the progress of the polymerization, it is preferable to set the inside of the reactor to an atmosphere of nitrogen, argon gas or the like. Polymerization temperature, polymerization time about the type of vinylidene chloride and polymerizable vinyl monomer,
The amount, the type and amount of the polymerization initiator, the type and amount of the chain transfer agent, etc. are appropriately determined, but are generally preferably from 30 ° C to 90 ° C for 10 hours to 100 hours, more preferably 20 hours.
６０60 hours, more preferably 25-50 hours.

The vinylidene chloride copolymer of the present invention may contain a lubricant, a gelling improver, a pH adjuster, a chain transfer agent, an antistatic agent, a crosslinking agent, a defoaming agent, a stabilizer, a filler,
Additives such as an antioxidant and a scale adhesion inhibitor may be added. These can be added at the beginning of polymerization, during polymerization, or after polymerization. In the present invention, the stirrer of the polymerization vessel is not particularly limited, and a baffle may be used if desired. Examples of the stirrer include a turbine blade, a fan turbine blade, a Faudler blade, and a blue margin blade which are usually used for polymerization of a vinyl chloride monomer. Of these, use a Faudler blade whose droplet diameter can be easily controlled. Is preferred. Finger type, cylindrical type, baffle
D type and loop type are exemplified.

When a Faudler blade is used, the stirring blade speed is defined by the following equation. Stirring blade speed (m / sec) = n · π · d / 60 (n: stirring blade rotation speed (rpm), π: circumferential ratio, d: stirring blade span) The stirring blade speed is determined by the stability of suspension polymerization. , 0.7m / sec
The above is preferable, and from the viewpoint of the particle diameter of the obtained polymer, it is preferably 3.0 m / sec or less. More preferably, 1.
In the range of 0 to 2.5 m / sec, the stirring conditions are selected so that the ratio of the particles having a particle size of less than 150 μm is 3 wt% or less, depending on the combination with the concentration of the suspension and dispersant described above.

The weight average particle size of the vinylidene chloride-based copolymer particles obtained by the above method is 200 to 500 μm.
m, and the mass ratio of the fine particles smaller than 150 μm is 3 wt% or less. The bulk specific gravity is 0.8 from the viewpoint of quantitative supply stability of the vinylidene chloride-based copolymer particles.
It is preferable that the ^{0g / cm 3 ~1.0g / cm 3} .
More preferably, the weight average particle diameter is 230 to 400 μm.
m, the mass ratio of fine particles smaller than 150 μm is 1.5 wt.
% Or less, and a bulk specific gravity of 0.90 g / cm ^{3 to} 0.98 g /
cm ³ .

Further, the weight average molecular weight of the vinylidene chloride copolymer particles is preferably about 60,000 to 200,000, and more preferably 70,000 to 150,000. More preferably, it is 80,000 to 130,000. As the weight average molecular weight, a weight average molecular weight in the above range is selected from the viewpoint of extrusion processability and gas barrier properties. Further, two or more kinds of vinylidene chloride-based copolymer particles having different weight average molecular weights are blended at an arbitrary ratio, and the weight-average molecular weight of the blended vinylidene chloride-based copolymer composition is in the range of 60,000 to 200,000. The composition may be as follows.

The molecular weight distribution was measured using a weight average molecular weight in terms of polystyrene by gel permeation chromatography. In the extrusion using the vinylidene chloride-based copolymer particles obtained in the present invention, known plasticizers, heat stabilizers, processing aids, light stabilizers,
Additives such as pigments, lubricants, antioxidants, fillers, and surfactants can be blended.

For example, epoxidized oils and resins such as dioctyl phthalate, acetyl tributyl citrate, dibutyl sebacate, dioctyl sebacate and diisobutyl adipate, epoxidized soybean oil, epoxidized linseed oil, amide derivatives of alkyl esters, magnesium hydroxide Plasticizers such as tetrasodium pyrophosphate, magnesium oxide and calcium hydroxyphosphate, polyethylene oxide, paraffin wax, polyethylene wax, waxes such as montan ester wax, heat stabilizers, processing aids, those acting as lubricants, and more. Is a filler such as silicon oxide and calcium carbonate,
And, surfactants such as sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters,
Various additives are included.

When a plasticizer and a stabilizer are added to the above additives, the amount is preferably about 1 to about 10 parts by weight, more preferably 2 to 6 parts by weight, based on 100 parts by weight of the vinylidene chloride-based copolymer particles. Department. Some of these additives may be added during the polymerization of the vinylidene chloride-based copolymer particles. The additives are adsorbed or absorbed by the vinylidene chloride copolymer during extrusion, and contribute to extrusion processability.

The method of mixing the vinylidene chloride-based copolymer particles and the additives is not particularly limited, and a conventional method can be applied. For example, kneading with a two-roll machine, mixing with a blender such as a blade blender or ribbon blender, mixing with a Henschel high-speed mixer, etc.
Either a heating mixing method exceeding 60 ° C. or a low temperature mixing method at 60 ° C. or less can be applied. It is preferable to mix in a temperature range of 50 ° C. to room temperature, from the viewpoint of preventing thermal deterioration of the obtained vinylidene chloride copolymer-containing resin composition.

In the method of supplying a composition comprising vinylidene chloride-based copolymer particles and additives as raw materials, it is preferable to use a feeder which continuously measures and quantitatively supplies the composition to a hopper of an extruder. . Examples of the feeder include a screw feeder, a circle feeder, an electromagnetic feeder, a weight feeder, a positive displacement feeder, and the like. Among them, the method of mixing using a weight feeder can suppress fluctuations in the motor load and the amount of extrusion during the extrusion process, enabling steady supply to the extruder, and ensuring stable extrusion. This is preferred because

The composition comprising the vinylidene chloride-based copolymer particles of the present invention and an additive is melt-extruded and formed into a stretched or unstretched film or sheet. As a molding method, a known method such as an inflation extrusion molding method using a circular die can be applied. A film obtained by stretching, particularly preferably by biaxial stretching, has heat shrinkability or is suitably used as a heat-resistant film that can be retorted. The stretching ratio is 2.0 in the machine direction.
It is preferably from 4.5 to 4.5 times and 3.0 to 5.0 times in the horizontal direction. The thickness of the film is preferably 5 to 30 μm, more preferably 10 to 25 μm as a single film. It is also used as a double film depending on the application.

The main method of use for food packaging is, for example, after inflation, a double film is formed by stacking two sheets, slitting the ears at both ends of the film, sealing the cylindrical shape with a packaging machine, and filling the contents. It is used to obtain a package with both ends gripped. Further, the film of the present invention may be laminated with a film made of the same kind of resin, a vinylidene chloride copolymer, or another resin or resin composition capable of being co-extruded.

When extruding a composition obtained from the vinylidene chloride-based copolymer particles and additives, the extrudability is improved by supplying the composition to an extruder via a vacuum hopper. That is, the use of the vacuum hopper is effective in reducing the adhesion and decomposition of the resin at the outlet of the die, the coloring of the resin and the outflow of decomposed products, and the reduction of the burst of bubbles during inflation molding. The degree of vacuum of the vacuum hopper is −6.66 × 10 ⁻² MPa or less,
Preferably -10.1x from -7.99x10 ^-2 MPa
It is in the range of 10 ^-2 MPa. By supplying the resin composition to an extruder via a vacuum hopper set under such conditions, extrudability and stretchability can be stably maintained. It is stretched by a known method via a melt extruder connected to the lower part of a vacuum hopper, or is formed into a film, a sheet or the like without stretching.

The composition comprising the vinylidene chloride-based copolymer particles is stably supplied to the melt extruder by the above-mentioned extrusion method, so that the fluctuation of the load of the motor of the extruder and the fluctuation of the extrusion amount are reduced. Can be kept small. Alternatively, these vinylidene chloride copolymer-containing resin compositions may be arranged in a gas barrier layer and formed into a multilayer film or sheet by a coextrusion method or a lamination method.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
In the examples and comparative examples, the following compounds and equipment were used. Suspension dispersant (A1) Methylcellulose (2% aqueous solution viscosity 4000 mPa · s) (A2) Hydroxypropyl methylcellulose (2% aqueous solution viscosity 4000 mPa · s) (A3) Hydroxypropyl methylcellulose (2% aqueous solution viscosity 400 mPa · s) Stirrer blade ( S1) Faudler wing

The method for measuring and evaluating the characteristics in the present invention will be described. 1) Particle Size Distribution of Vinylidene Chloride Copolymer Particles The weight average particle diameter and the ratio of particles smaller than 150 μm are as follows:
It was measured by a particle size distribution measuring method using a Coulter Multisizer particle measuring device TA-II (manufactured by Nikkaki Co., Ltd.). Level value and evaluation of weight average particle size: 200 to 500 μm: ◎ Less than 150 μm: × Level value and evaluation of ratio of vinylidene chloride copolymer particles less than 150 μm: 0 to 1.5 wt% or less What falls within the range: ◎ What falls within the range of 1.5 wt% to 3 wt% or less: ○ More than 3 wt%: × 2) Bulk specific gravity Measurement was performed in accordance with JIS K-6722. (Powder tester PT-R type (powder measuring device manufactured by Hosokawa Micron Co., Ltd.)) The following judgment was made based on the value of the bulk specific gravity. 0.9 to 1.0 g / cm ³ : ◎ 0.8 to 0.9 g / cm ³ : ○ Less than 0.8 g / cm ³ : × 3) Weight average molecular weight The weight average molecular weight of the polymer particles is determined by gel permeation. It was measured as follows by chromatography (GPC). Measuring apparatus: Gel permeation chromatograph HLC-8020 manufactured by Tosoh Corporation Column: TSKgel SuperHM-H (manufactured by Tosoh Corporation) 7.8 mm × 30 cm × 2 Eluent: THF, flow rate: 1 ml / min, temperature: 40
° C, detection: RI 4) Variation rate of supply rate of vinylidene chloride-based copolymer particles Using about 50 kg of vinylidene chloride-based copolymer particles,
The feed rate is set at 100kg / with a screw feeder.
hr, the supply amount during a certain period of time in the range of 10 to 20 minutes is measured (n = 5), and the simple average value and standard deviation thereof are obtained.

The rate of change of the supply speed is obtained by the following equation, and is used as a criterion for determining the fluidity. Here, Phytron SK-S (manufactured by Hosokawa Micron Corporation) was used as the screw type feeder. Fluctuation rate (%) of supply speed = (standard deviation / simple average value) x
100 The liquidity was determined as follows based on the rate of change. 0% to 5%: ◎ (no problem in processability) Exceeding 5%: × (poor processability, uneven supply) 5) Extrusion characteristics Average film thickness and standard deviation at about 300 m length of the produced film Was measured, and the rate of change of the film thickness was determined by the following equation, and was used as a criterion for judging the extrudability. Fluctuation rate (σ) (%) of film thickness = (standard deviation / average film thickness) × 1000% to 2%: （(no problem in extrusion processability) Exceeding 2%: × (poor extrusion processability, (Thickness unevenness occurs) <Comprehensive evaluation> Symbol Level value and evaluation ◎: All evaluation items are satisfied as ◎. ：: Each evaluation item is satisfied, but a part of ○ is included. ×: Poor in characteristics.

[0044]

Embodiment 1 Faudler blade (span diameter 400 mm),
In a reactor (internal volume 300 liters) equipped with a finger baffle, a thermometer and a nitrogen gas inlet tube, a suspension 100 in which deionized water and a suspending dispersant (A1) were added and dissolved was added.
The parts by mass were adjusted (concentration of the suspension / dispersant: 0.05%). Next, 80 parts by mass of vinylidene chloride, 20 parts by mass of vinyl chloride, 0.15 parts by mass of initiator diisopropyl peroxydicarbonate, and 2 parts of epoxidized linseed oil were added, and the stirring blade speed was set to 1.4 m / sec. 45 below
Heated to ° C. to initiate polymerization. After continuing the reaction for about 10 hours, the temperature was raised to 55 ° C. in about 1 hour, and the stirring speed was set to 1.2 times the initial speed (1.68 m / sec), and further increased by 1 hour.
The polymerization was continued for 5 hours. After completion of the reaction, the separated vinylidene chloride-based copolymer particles have a weight average particle size of 26.
0 μm, the mass ratio of less than 150 μm in particle size is
2.2 wt%. The bulk specific gravity is 0.90g
/ Cm ³ .

The copolymer particles were dissolved in tetrahydrofuran, and the molecular weight in terms of polystyrene was measured by gel permeation chromatography. As a result, the weight average molecular weight was 120,000. Table 1 shows the evaluation results of the characteristics of the vinylidene chloride-based copolymer particles.

[0046]

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the concentration of the suspension / dispersant was 0.03% and the stirring blade speed was 3.1 m / sec. The weight average molecular weight was 123,000. The results are shown in Table 3.

[0047]

Example 2 The same polymerization as in Example 1 was carried out except that the concentration of the suspension and dispersant was 0.03% and the stirring blade speed was 1.2 m / sec. The weight average molecular weight was 116,000. The results are shown in Table 1.

[0048]

Comparative Example 2 The same polymerization as in Example 1 was carried out except that the concentration of the suspension / dispersant was 0.1% and the stirring blade speed was 0.6 m / sec. The weight average molecular weight was 120,000.
The results are shown in Table 3.

[0049]

Example 3 The same polymerization as in Example 1 was carried out except that the concentration of the suspending and dispersing agent was 0.03% and the stirring blade speed was 1.0 m / sec. The weight average molecular weight was 115,000. The results are shown in Table 1.

[0050]

Example 4 A suspension / dispersant (A2) was used at a concentration of 0.
Polymerization was carried out in the same manner as in Example 1, except that the stirring blade speed was set to 1.2 m / sec and the stirring blade speed was set to 1.2 m / sec. Weight average molecular weight is 11
It was 8,000. The results are shown in Table 1.

[0051]

Comparative Example 3 The suspension / dispersion agent was designated as (A2) and the concentration was 0.1
%, And the stirring blade speed was set to 0.6 m / sec.
The same polymerization was carried out. The weight average molecular weight is 121,00
It was 0. The results are shown in Table 3.

[0052]

Example 5 A suspension / dispersing agent (A3) was used and the concentration was adjusted to 0.
Polymerization was carried out in the same manner as in Example 1 except that the stirring blade speed was 1.0 m / sec and 1%. The weight average molecular weight is 12
It was 1,000. The results are shown in Table 1.

[0053]

Example 6 Vinylidene chloride (VD) obtained in Example 1
Dibutyl sebacate as an additive was added to vinyl chloride (VC) copolymer particles (vinylidene chloride / vinyl chloride mass ratio: VD / VC = 80/20) in an amount of 3 parts by mass based on 100 parts by mass of the total vinylidene chloride copolymer. Parts, antioxidants, lubricants,
A total of 1 part by mass of a red pigment was added to prepare a composition comprising vinylidene chloride-based copolymer particles.

Next, the extruder was extruded in a ring shape with an extruder having a diameter of 40 mm at a vacuum pressure of a vacuum hopper of about -9.06 × 10 ^-2 MPa, and then rapidly cooled in a cooling bath at 10 ° C. by a conventional method.
After passing through a hot water bath at 0 ° C., air was press-fitted between two sets of pinch rolls having different rotational surface speeds and expanded, and stretched and oriented 2.8 times in the longitudinal direction and 3.7 times in the width direction. The obtained film had a single thickness of 20 μm. Thickness of the prepared film 100m and the variation rate (σ) of the thickness
Was measured. The results are shown in Table 2.

[0055]

Example 7 Example 6 was repeated except that the degree of vacuum was changed to -7.99 × 10 ^-2 MPa using the copolymer particles obtained in Example 2.
The same was done. The results are shown in Table 2.

[0056]

Example 8 Example 6 was repeated except that the degree of vacuum was changed to -7.99 × 10 ^-2 MPa using the copolymer particles obtained in Example 3.
The same was done. The results are shown in Table 2.

[0057]

Example 9 Example 6 was repeated except that the degree of vacuum was -7.99 × 10 ^-2 MPa using the copolymer particles obtained in Example 4.
The same was done. The results are shown in Table 2.

[0058]

Example 10 Using the copolymer particles obtained in Example 5,
The same operation as in Example 6 was performed except that the degree of vacuum was changed to −6.66 × 10 ⁻² MPa. The results are shown in Table 2.

[0059]

Comparative Example 4 The same procedure as in Example 6 was performed using the copolymer particles obtained in Comparative Example 1. The results are shown in Table 4.

[0060]

Comparative Example 5 The same procedure as in Example 6 was performed using the copolymer particles obtained in Comparative Example 2. The results are shown in Table 4.

[0061]

Comparative Example 6 The procedure of Example 6 was repeated except that the degree of vacuum was changed to -7.99 × 10 ⁻² MPa using the copolymer particles obtained in Comparative Example 3.
The same was done. The results are shown in Table 4.

[0062]

Comparative Example 7 The same operation was performed as in Example 6, except that no vacuum hopper was used. The results are shown in Table 4.

[0063]

Comparative Example 8 The same operation was performed as in Comparative Example 4, except that no vacuum hopper was used. The results are shown in Table 4.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

From the examples and comparative examples, it was demonstrated that the present invention can provide a film having excellent extrusion processability and a uniform film thickness.

[0069]

The vinylidene chloride copolymer particles having a specific particle size distribution and bulk specific gravity obtained from the present invention are used.
A film excellent in extrusion processability (for example, reduction in variation in extrusion amount, uniformity of film thickness during inflation molding) can be obtained. In addition, an extrusion method for supplying a composition comprising vinylidene chloride-based copolymer particles to an extruder via a vacuum hopper and supplying the vinylidene chloride-based copolymer particles to an extruder using a quantitative supply device The extrusion process characteristics can be improved by a film production method comprising the steps and the extrusion process method.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C08L 27:08 C08L 27:08 F term (reference) 4F070 AA22 AB21 DA05 4F071 AA25 AH04 BA01 BB06 BB09 BC01 BC12 4F207 AA01D AA13L AA14D AA14E AA15L AA20L AA21L AG01 KA01 KA17 KA19 KF01 KL43 4J100 AA02Q AA03Q AB02Q AB03Q AB04Q AB08Q AC03Q AC04P AE02Q AE03Q AE04Q AG02Q AG04Q AJ08Q AJ09Q AL03Q AL04Q AL08QFA09 DA08 FA03

Claims (7)

[Claims] Claims: 1. A weight-average particle size of 200 to 500 μm.
Wherein the proportion of particles having a particle diameter of less than 150 μm is 3 wt% or less. 2. A bulk density of the vinylidene chloride copolymer ^{particles, 0.80g / cm 3 ~1.0g / cm} 3 a vinylidene chloride copolymer particles according to claim 1, characterized in that. 3. The vinylidene chloride-based copolymer is obtained by copolymerization of vinylidene chloride with one or more monomers selected from polymerizable vinyl monomers. Copolymer particles. 4. The polymerizable vinyl monomer is vinyl chloride,
The copolymer particles according to any one of claims 1 to 3, wherein the copolymer particles are at least one selected from methyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, acrylonitrile, and styrene. 5. The vinylidene chloride-based copolymer particles according to claim 1, which is extruded by an extruder provided with a weight feeder capable of performing a quantitative supply. Extrusion processing method. 6. An extrusion method comprising extruding the vinylidene chloride-based copolymer particles according to claim 1 by an extruder capable of controlling the degree of vacuum. 7. A film obtained from the vinylidene chloride-based copolymer particles according to claim 1.