JP2000309643A - Saponified ethylene-vinyl acetate copolymer film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EVOH-based film comprising an unstretched or stretched film of a saponified ethylene-vinyl acetate copolymer (EVOH) which is excellent in slipperiness, transparency and appearance characteristics, and the same. It is an object of the present invention to provide a method capable of stably producing such an EVOH-based film. An unstretched or stretched EVOH film containing inorganic particles such as an inorganic oxide, wherein the average particle size of the inorganic particles is 1 μm or more and 0.5 times or less the film thickness, and the inorganic material in the film is Particle content is 3
An EVOH-based film having a concentration of 0 to 5000 ppm. E
The sum of the metal contents of Na and K contained in VOH is 0.01
It is preferably from 50 to 50 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unstretched or stretched film of a saponified ethylene-vinyl acetate copolymer (that is, an ethylene-vinyl alcohol copolymer) having excellent slipperiness and transparency. The invention also relates to an industrial production method for the stretched film. In the following, "ethylene-vinyl acetate copolymer saponified",
Abbreviated as "EVOH" as necessary.

[0002]

2. Description of the Related Art EVOH films have gas barrier properties,
Because of its excellent properties such as fragrance retention, solvent resistance, and oil resistance, it is widely used in various packaging applications including food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, and agricultural chemical packaging materials.

[0003] As one of the manufacturing methods of the EVOH film,
There is known a method in which a raw material EVOH is supplied to an extruder and melt-extruded from a T-die onto a casting roll. By stretching the unstretched film thus obtained,
An EVOH stretched film is obtained. EVOH stretched film, especially biaxially stretched film, compared to unstretched film,
There is an advantage that water resistance, hot water resistance, and impact resistance are improved, and a decrease in gas barrier properties under high humidity is suppressed.

Generally, when biaxially stretching an EVOH film, the crystallinity of the EVOH is strong, so that oriented crystallization is strongly exhibited in the longitudinal stretching as the primary stretching, and the film is stretched in the transverse stretching as the secondary stretching. Are not uniformly stretched, so that stretching unevenness occurs and the film is easily broken.

In order to improve this point and to improve physical properties, Japanese Patent Publication No. Sho 60-26697 (JP-A-56-30) has been proposed.
827), the ethylene content X is 20 to
An unstretched film made of EVOH having a mole percentage of 55 mol% and a saponification degree of 98 mol% or more, and having a specific gravity d of d <1.320-4.3 × 10 ⁻³ X, having a water content of 3.5% or less and desirably substantially free of water There is shown a method for producing an EVOH film which is biaxially or multiaxially stretched so that the area magnification becomes 4 to 20 times at a temperature of 50 to 130 ° C. in this state.

[0006] Similarly, Japanese Patent Application Laid-Open No. 56-137,728 discloses that the ethylene content X is 20 to 55 mol% and the saponification degree is 9%.
An unstretched film composed of 6 mol% or more of EVOH and having a specific gravity d of d <1.320-4.3 × 10 ⁻³ X is used.
A method for producing an EVOH uniaxially stretched film that is stretched at 100 ° C. is shown.

Japanese Patent Application Laid-Open No. 61-235127 discloses E
A substantially amorphous and substantially moisture-free unstretched film made of VOH is heated to a temperature range of 50 to 60 ° C. and stretched 2.5 to 3.5 times in a longitudinal direction by a roll-type longitudinal stretching machine. In one step, the film stretched in the longitudinal direction in the first step is subjected to 70 to 9 stretching by a tenter-type transverse stretching machine.
In a temperature range of 5 ° C., a second step of stretching in the transverse direction by 2.7 to 4.0 times, a film stretched in the transverse direction in the second step is
A method for producing an EVOH biaxially stretched film, comprising a third step of heat-setting in a temperature range having a lower limit of 110 ° C. and an upper limit of 5 ° C. lower than the melting point of the raw resin, is shown.

[0008] In the above three documents, the raw material EVOH
Is supplied to an extruder and melt extruded from a T-die onto a casting roll to obtain an unstretched EVOH film.

Although there is no description about a biaxially stretched film, JP-A-1-262131 discloses an average particle size of 0.02.
Surface-treated EVO having polymer particles having a glass transition temperature of 50 ° C. or more at 0.003 to 1.0 g / m ² per side.
H film is shown. Here, a typical example of the polymer particles is a methyl methacrylate-styrene copolymer. Surface treatment is performed by applying and drying the polymer particles using polyvinyl alcohol as a binder, and together with the polymer particles, silicon oxide, titanium dioxide, clay,
There is also a statement that bentonite and the like may be appropriately used in combination. The purpose of the surface treatment is to improve heat resistance without impairing transparency and gas barrier properties.

[0010]

However, the above-mentioned Japanese Patent Publication No. 60-266, which controls the specific gravity of the unstretched film, is used.
Even in the method for producing an EVOH stretched film described in JP-A-97-30827 or JP-A-56-137828, film breakage still occurs during stretching and stable production is difficult. In some cases, smooth stretching is possible, but desired physical properties cannot be obtained in terms of slipperiness and transparency.

EVO disclosed in Japanese Patent Application Laid-Open No. Sho 61-235127
Although the method for producing an H biaxially stretched film can provide satisfactory results in terms of stretching conditions, there remains a problem in the future in terms of obtaining an EVOH biaxially stretched film having good slipperiness and transparency.

The surface-treated EVOH film disclosed in Japanese Patent Application Laid-Open No. 1-262131 is to improve heat resistance by surface treatment. The purpose, means, and effects are different from those of the present invention. A drying step as well as a construction step is required, which is disadvantageous in terms of industrial production.

Under such a background, the present invention provides an EVOH-based film comprising an unstretched or stretched EVOH film having excellent slipperiness, transparency, and appearance characteristics, and provides such an EVOH-based film. It is an object of the present invention to provide a method that can be manufactured stably.

[0014]

The saponified ethylene-vinyl acetate copolymer (EVOH) film of the present invention is obtained by unstretching or stretching a saponified ethylene-vinyl acetate copolymer (EVOH) containing inorganic particles. The film is characterized in that the average particle diameter of the inorganic particles is 1 μm or more, 0.5 times or less the film thickness, and the content of the inorganic particles in the film is 30 to 5000 ppm.

The method for producing a saponified ethylene-vinyl acetate copolymer (EVOH) film of the present invention is a method for producing a saponified ethylene-vinyl acetate copolymer (E) containing inorganic particles.
The unstretched film of VOH) is biaxially stretched, and the average particle size of the inorganic particles is 1 μm or more, 0.5 times or less the film thickness after biaxial stretching, and the content of the inorganic particles in the film is 30 to In order to obtain a biaxially stretched film satisfying the condition of 5000 ppm, the unstretched film is stretched in the machine direction at a temperature of 50 to 70 ° C. and a stretching ratio of 2.5 to 4.0 by a roll stretching machine to form a uniaxially stretched film. Obtained longitudinal stretching step, the obtained uniaxially stretched film at a temperature of 60 to 120 ° C. and a stretching ratio of 2.5 to
A transverse stretching step of stretching in the transverse direction under a condition of 5.0 times to obtain a biaxially stretched film.
It is characterized in that a heat setting step of heat setting is carried out under a temperature condition of from 0 ° C. to 5 ° C. lower than the melting point of the raw material resin.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

<< EVOH-based film >> EVOH of the present invention
The system film is composed of an unstretched or stretched EVOH film containing inorganic particles. The average particle diameter of the inorganic particles is 1 μm or more and 0.5 times or less of the film thickness, and the content of the inorganic particles in the film is 30 to 50 μm.
It is required to be 00 ppm.

<EVOH> EVOH has an ethylene content of 10 to 60 mol% (preferably 20 to 60 mol%, more preferably 25 to 55 mol%) and a saponification degree of a vinyl acetate component of 90 mol% or more ( Preferably, it is 95 mol% or more, more preferably 98 mol% or more. When the ethylene content is too small, the water resistance of the film is insufficient, and the gas barrier property at high humidity is insufficient. On the other hand, when the ethylene content is too large, the gas barrier property is insufficient. When the degree of saponification is too low,
The film has insufficient water resistance and gas barrier properties.

The EVOH may be a mixture of two or more EVOHs having different ethylene contents and different degrees of saponification. In addition, an ethylene-vinyl acetate copolymer (EV
Copolymerization or graft polymerization for obtaining A), or EV
Modified EVOH by an addition reaction utilizing a functional group of OH may be used. Furthermore, the blend may be a blend of another polymer after the EVOH is produced or produced.

Examples of modification by copolymerization or graft polymerization of EVOH include propylene, isobutylene, α-octene,
α-olefins such as α-dodecene and α-octadecene;
Acrylic acid, methacrylic acid, crotonic acid, maleic acid,
Ethylenically unsaturated carboxylic acids such as maleic anhydride and itaconic acid or salts, anhydrides and mono- or dialkyl esters thereof; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; alkyl vinyl ethers; Polyoxyalkylene (meth) such as ethylene (meth) allyl ether and polyoxypropylene (meth) allyl ether
Allyl ether; polyoxyalkylene (meth) acrylate such as polyoxyethylene (meth) acrylate and polyoxypropylene (meth) acrylate; polyoxyalkylene (meth) such as polyoxyethylene (meth) acrylamide and polyoxypropylene (meth) acrylamide ) Acrylamide, polyoxyethylene (1-
(Meth) acrylamide-1,1-dimethylpropyl)
Esters: polyoxyethylene vinyl ether, polyoxypropylene vinyl ether; polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine; ethylene sulfonic acid, allyl sulfonic acid,
Olefin sulfonic acids such as methallyl sulfonic acid or salts thereof; N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride; dimethylallyl vinyl ketone; monomers containing a pyrrolidone ring such as N-vinylpyrrolidone; vinyl chloride, vinylidene chloride; Modified with a monomer such as a monomer; allyl acetate; isopropenyl acetate;

Examples of modification by addition reaction using a functional group of EVOH include modification by cyanoethyl group, modification by addition of alkylene oxide (addition of polyether component) and the like.

Examples of blends obtained by blending other polymers after or after the production of EVOH include polyolefins, polyamides, polyesters, polystyrenes, polyvinyl alcohols, polyurethanes, polymethyl methacrylates and modified products thereof as other polymers. This is the case. At this time, about 0.1 to 150 parts by weight (especially 0.1 to 100 parts by weight, further 0.1 to 80 parts by weight) with respect to 100 parts by weight of the EVOH (including the modified product).
(Parts by weight) Other resins can be blended.

The above EVOH has a sum of the metal contents of Na and K contained therein of 0.01 to 50 ppm (particularly 0.1 to 30 ppm).
ppm). Of the metal content of Na and K
If the sum is less than 0.01 ppm, it is colored (yellowing) during extrusion.
On the other hand, when the sum exceeds 50 ppm, the frequency of gel generation increases, and as a result, the film tends to break during stretching. Although the content of other metals is not particularly limited, the sum of the metal contents of Ca and Mg is 1 to 200 ppm (preferably 2 ppm).
１５０150 ppm), of which the metal content of Ca is 100
The content of Ca and / or Mg whose content of Mg is less than 100 ppm or less is effective in suppressing the generation of gel.

<Inorganic particles> Examples of the inorganic particles include inorganic oxides (including composite oxides) such as silicon dioxide, aluminum oxide, zirconium oxide, cerium oxide, molybdenum oxide, talc, mica, kaolin, and clay. Of these, silicon oxide is particularly important. Calcium carbonate, barium sulfate, silicon carbide, boron carbide, tungsten carbide, aluminum nitride, titanium nitride, silicon nitride and the like can also be used. Two or more of these inorganic particles may be used in combination.

The inorganic particles are required to have an average particle size of 1 μm or more and 0.5 times or less (preferably 0.4 times or less) of the film thickness. When the average particle size is too small, the effect of improving the slip property is insufficient. On the other hand, when the average particle size exceeds 0.5 times the film thickness, breakage tends to occur during stretching. However, even when the film thickness is large, when the particle size is extremely large, the film forming property and the stretchability are negative, so the upper limit of the average particle size should be limited to about 10 μm.

The content of the inorganic particles in the film is 30
5,000 ppm, preferably 50-1000 ppm, more preferably 70-500 ppm. When the content of the inorganic particles is less than 30 ppm, the effect of improving the slipperiness is insufficient. On the other hand, when it exceeds 5000 ppm, the transparency of the film is lowered and the film is liable to be broken during stretching.

<< Manufacture of EVOH unstretched film >> EVO
The H unstretched film is preferably manufactured as follows. That is, the raw material EVOH is supplied to an extruder and melt-extruded from a T-die onto a casting roll. As the extruder, a general screw type extruder such as a single screw extruder or a twin screw extruder is used. The melting temperature is
10 to 80 ° C (preferably 20 to 6) from the melting point of EVOH.
0 ° C.) A high temperature is appropriate, but it is preferable to set the temperature as low as possible in order to suppress the generation of gel as long as the kneading of the resin is sufficient.

When using only a screw type extruder, the quantitative extrudability is lacking, and the film thickness accuracy in the flow direction (MD direction) of the unstretched film may be deteriorated. When such troubles occur, it is desirable to provide a gear pump between the extruder and the T-die. As the main body structure of the gear pump, an in-line type, a block mount type, or the like is used, the number of gears is two or three, and the gear shape is a spar, helical, or the like.

For forming on a casting roll,
An electrostatic pinning method, an air knife method, a vacuum chamber method, or the like is applied. Then, the raw resin melt-extruded from the T-die is brought into close contact with a casting roll maintained at a temperature of usually 60 ° C. or lower, preferably 40 ° C. or lower, rapidly cooled, and becomes an unstretched film.

This unstretched film is then subjected to longitudinal stretching. Before that, the unstretched film may be immersed in a hot bath or the like, if necessary, to make the water content of the unstretched film 0.1% by weight or more. .

<< Production of EVOH Stretched Film >> The unstretched film thus obtained is stretched to obtain an EVOH stretched film. Stretching may be uniaxial or biaxial (including multiaxial), but since biaxial stretching is important, the production of a biaxially stretched film from an unstretched film will be described below. The biaxially stretched film is preferably manufactured through the following longitudinal stretching step, transverse stretching step, and heat setting step.

In the longitudinal stretching step, the unstretched EVOH film is stretched in the longitudinal direction at a temperature of 50 to 70 ° C. and a stretching ratio of 2.5 to 4.0 by a roll stretching machine to obtain a uniaxially stretched film.

The roll stretching machine is composed of a plurality of rolls and a plurality of nip rolls capable of controlling the temperature and controlling the speed. By changing the linear speed of the low-speed roll and the high-speed roll in one or more stages, the longitudinal stretching of the film is performed. The magnification can be changed variously.

In the longitudinal stretching, when the stretching temperature (film temperature) is lower than 50 ° C., the stretching stress is too high and the film is easily broken, and when the stretching temperature exceeds 70 ° C., the film sticks to the stretching roll. Also, crystallization proceeds rapidly even if it does not stick, so that the next transverse stretching becomes difficult, which tends to cause film breakage.

In this longitudinal stretching, the stretching ratio is 2.5
If the ratio is less than 1, the desired orientation cannot be imparted to the finally obtained film, while if the stretching ratio exceeds 4.0, the film is liable to break in the transverse stretching step. The heating of the film is preferably performed by a roll of a roll stretching machine.

In the transverse stretching step, the uniaxially stretched film obtained in the longitudinal stretching step is heated to a temperature of 60 to 1 by a tenter type transverse stretching machine.
This is a step of obtaining a biaxially stretched film by stretching in the transverse direction at 20 ° C. and a stretching ratio of 2.5 to 5.0.

[0037] Tenter-type transverse stretching machines are well known to those skilled in the art. The transverse stretching ratio can be variously changed by adjusting the interval between tenters at which both ends in the film width direction are gripped.

When the stretching temperature is less than 60 ° C. in the transverse stretching, the stretching stress is too high and the film is easily broken, and when the stretching temperature is more than 120 ° C., the orientation effect by stretching cannot be sufficiently obtained. Only a film having low target strength and poor thickness accuracy can be obtained.

When the stretching ratio is less than 2.5 times in the transverse stretching, the desired orientation cannot be imparted to the finally obtained film. On the other hand, when the stretching ratio exceeds 4.0 times, the film cannot be obtained. It is easy to break. The film is heated by a hot air oven, a heater type oven, or a combination of both.

In the heat setting step, the biaxially stretched film obtained in the transverse stretching step is heated at 110 ° C.
This is a step of heat setting under a temperature condition of a temperature lower by ° C.
A more preferred temperature range is from 120 ° C. to a temperature 10 ° C. lower than the melting point of the raw resin.

The heat setting is performed to improve the dimensional stability of the biaxially stretched film. If the heat setting temperature is too low, the heat setting will be insufficient, while if it is too high, the surface may whiten or have holes and break during heat setting. The heat setting may be performed in any state of the film in a tensioned state or a relaxed state, or a state in which both are combined. When performing in a relaxed state,
The relaxation rate is preferably 10% or less. The heating of the film can be performed in the same manner as in the case of the transverse stretching machine.

In the above, it is preferable that the transfer time of the uniaxially stretched film obtained in the longitudinal stretching step to the transverse stretching step (the transfer time to the transverse stretching start position) is as short as possible, for example, within 5 seconds. By such a short-time transfer, the progress of the orientation and crystallization accompanying the longitudinal stretching is suppressed, and the film breakage which is a concern during the transverse stretching is effectively prevented. In addition, since the transverse stretching step is performed at a higher stretching temperature than the longitudinal stretching step, it is preferable to preheat the film to a necessary temperature during the transfer.

<< Lamination >> The EVOH-based film (unstretched film or stretched film) obtained above can be used as it is as a single-layer film, but can also be used as a laminate laminated with a substrate.

A typical example of the laminate is obtained by laminating another film on one or both sides of an EVOH-based film. In this case, for example, an organic titanium-based compound,
Lamination is performed using an appropriate adhesive such as an isocyanate (urethane) adhesive or a polyester adhesive.

Here, as another film to be laminated,
Polyolefin resins (linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene-acrylate copolymer, polypropylene , Propylene-
α-olefin (C 4-20 α-olefin) copolymers, homo- or copolymers of olefins such as polybutene and polypentene, or graft-modified products of these with unsaturated carboxylic acids or esters thereof, polystyrene resins And films of polyester resin, polyamide resin, polyvinyl chloride resin, polyvinylidene chloride resin, acrylic resin, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene and the like. Lamination with an EVOH film is also possible.

As the substrate, other than the film, for example, paper, woven fabric, non-woven fabric, knitted fabric, metal foil, wood material and the like can be used.

When the layer structure of the laminate is A for the EVOH film and B for the other substrate, A / B, A / B / A, B
/ A / B, A / A / B, A / B / B, B / B / A / B /
If the laminate includes two or more layers A and B, the layers A and B may be the same or different.

The EVOH film may be coated with another substance to form a composite film. As the coating substance at this time, in addition to the various resins described above, inorganic substances are also possible. As a coating method, a coating substance which is itself liquid or a solution, a dispersion liquid or a melt liquid of the coating substance is applied, and a film forming means such as drying, curing, cooling, and UV irradiation is taken according to the type of the coating liquid. Method, evaporation, sputtering,
A method of forming a film on ion plating or the like can be used.

<< Use >> EVOH obtained in this manner
Based films and their laminates have appearance characteristics, gas barrier properties,
It has excellent properties such as fragrance retention,
It is particularly useful as a film, sheet, tube, bag, or container for packaging agricultural chemicals, industrial chemicals, fragrances, oils, and the like, and can be used for other purposes such as agricultural materials.

[0050]

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

<Raw material EVOH> As the EVOH, one having an ethylene content of 32 mol% and a saponification degree of 99.8 mol%,
Two types having an ethylene content of 44 mol% and a saponification degree of 99.8 mol% were used. The former has a melting point of 183 ° C. and the latter has a melting point of 164 ° C. In addition, the quantification of the alkali metal and the alkaline earth metal was performed by atomic absorption spectrometry.

<Inorganic Particles, Organic Particles> As inorganic particles, silicon dioxide (SiO ₂ ) having an average particle size of 0.3 μm, 2 μm or 15 μm, and aluminum oxide having an average particle size of 2 μm
(Al ₂ O ₃ ) was used. For comparison, the average particle size is 0.05 μm
Polystyrene particles (PSt) were used.

<Particle-Containing EVOH Pellets>
The above particles are blended with OH, and the EVOH shown in the following Table 1 is mixed.
A pellet was prepared.

[0054]

[Table 1]  EVOH Metal content (ppm) Grain  Et SV Na + K Ca Mg type Particle size Content  EVOH 1 32 99.8 20 10 1 SiO_Two 2 200 EVOH 2 32 99.8 20 10 1 SiO_Two 0.3^# 200 EVOH 3 32 99.8 20 10 1 SiO_Two 15^# 200 EVOH 4 32 99.8 20 10 1 SiO_Two 2 20^#  EVOH 5 32 99.8 20 10 1 SiO_Two 2 7000^#  EVOH 6 44 99.8 100 10 1 Al_TwoO_Three 2 200 EVOH 7 32 99.8 3 65 0 SiO_Two 2 200 EVOH 8 32 99.8 1 0 25 SiO_Two 2 200 EVOH 9 32 99.8 2 35 15 SiO_Two 2 200EVOH10 32 99.8 110 10 1 PSt ^# 0.05 ^# 300  -Et is ethylene content (mol%), SV is saponification degree (mol%). -The particle size is the average particle size (μm), and the content unit is ppm.・^# The marks are outside the scope of the present invention.

<Film forming conditions> Under the following conditions, the above particle-containing EVOH is supplied to a single screw extruder, melt-extruded from a T-die via a gear pump, and cast to a diameter of 600 mm cooled to a temperature of 20 ° C. Quenched on roll. As a result, an unstretched EVOH film having a thickness of 20 μm was obtained. The thickness was adjusted by changing the rotation speed of the casting roll.

1. Extrusion conditions with a single screw extruder-Screw inner diameter: 65 mm-L / D: 28-Screw compression ratio: 3.8-Extrusion temperature: C₁ 210 ° C, C_Two 220 ° C, C_Three 230
° C, C_Four 230 ° C, C _Five 220 ° C

2. Gear pump ・ Number of gears: 2 ・ Gear shape: spur ・ Model: In-line type ・ Gear pump temperature: 220 ° C

3. T die ・ Coat hanger type manifold type ・ Die width: 450mm ・ Die temperature: 220 ℃

<Measurement conditions> Slipperiness of the obtained EVOH unstretched film and the EVOH biaxially stretched film described below,
The transparency and appearance were measured or evaluated under the following conditions. 1. Slipperiness (dynamic friction coefficient)-Measuring device: Friction tester "TR" manufactured by Toyo Seiki Co., Ltd.-Measuring conditions: 196 g load, 150 mm / min speed (23
C, 50% RH) Measurement surface: Cast surface / air surface Transparency (haze) ・ Using a haze meter manufactured by Nippon Denshoku Co., Ltd., JIS K710
Measured according to 5. 3. Appearance The film appearance was visually evaluated.

<Evaluation of EVOH unstretched film> Example 1, Comparative Example 1 The conditions and results when EVOH unstretched films were obtained using EVOH 1 to 10 in Table 1 are shown in Table 2 below.

[0061]

[Table 2]  EVOH used Dynamic coefficient of friction Haze (%)  Example 1a EVOH 1 0.5 0.6 Good Example 1b EVOH 6 0.6 0.8 Good Example 1c EVOH 7 0.5 0.7 Good Example 1d EVOH 8 0.5 0.6 GoodExample 1e EVOH 9 0.5 0.7 Good  Comparative Example 1a EVOH 2 measurement not possible^* 0.3 Good Comparative Example 1b EVOH 3 0.3 10 Extremely cloudy Comparative Example 1c EVOH 4 Not possible^* 0.4 Good Comparative Example 1d EVOH 5 0.3 40 Extremely cloudyComparative Example 1e EVOH10 measurement not possible ^* 0.1 good  ^* The mark indicates that the films do not move smoothly due to the large friction.

<Evaluation of EVOH Biaxially Stretched Film> Example 2, Comparative Example 2 EVOH 1, 5, 6, 7, 8, 9 in Table 1 was used to carry out a single EVOH in the same manner as in Example 1. The mixture was supplied to a shaft extruder, melt-extruded from a T-die via a gear pump, and quenched on a casting roll having a diameter of 600 mm cooled to a temperature of 20 ° C. to obtain an unstretched EVOH film. The thickness was adjusted by changing the rotation speed of the casting roll so that the final biaxially stretched film thickness became 15 μm. EVOH 2, 4, and 10 were excluded because the dynamic friction coefficient of the unstretched film was large, and EVOH 3 was excluded because it is apparent that the film would break during stretching.

Next, this unstretched film was used in Table 3 to be described later.
Under the conditions described above, continuously stretched longitudinally with a roll stretching machine,
Subsequently, transverse stretching was performed using a tenter-type stretching machine, and 5
After heat setting for 2 seconds, the humidity was adjusted to obtain an EVOH biaxially stretched film.

With respect to the thus obtained EVOH biaxially stretched film three hours after the stretching treatment, the slipperiness, transparency and appearance were measured or evaluated in the same manner as in Example 1, and the ASTM- The tensile strength (kg / mm ² ) in the machine direction and the transverse direction was measured under the conditions of 20 ° C. and 65% RH according to D-882 and ASTM-D-1922. In addition, the above-mentioned stretching treatment was continuously performed for 8 hours, and the number of breaks (including perforations) at that time was examined to evaluate the continuous stretchability. Table 3 shows the conditions and Table 4 shows the results.

[0065]

[Table 3]  EVOH usedLongitudinal stretching process Lateral stretching process Heat setting process  Type Temperature Magnification Temperature Magnification Temperature  Example 2a EVOH 1 60 3.0 90 3.9 150 Example 2b EVOH 1 60 3.2 90 4.2 150 Example 2c EVOH 1 60 3.5 90 4.0 150 Example 2d EVOH 6 58 3.2 90 4.2 145 Example 2e EVOH 7 60 2.9 90 3.9 150 Example 2f EVOH 8 60 3.0 90 4.0 150Example 2g EVOH 9 60 3.3 90 4.1 150  Comparative Example 2a EVOH 5^# 60 3.0 90 3.9 150Comparative Example 2b EVOH 1 60 2.9 125 ^# 3.8 150  The temperature is ° C and the magnification is the stretching magnification.^# The marks are outside the scope of the present invention.

[0066]

[Table 4]  Dynamic friction haze appearanceTensile strength Continuous stretchabilityCoefficient (%) TD MD Number of breaks  Example 2a 0.5 0.7 Good 22 26 1 Example 2b 0.5 0.6 Good 24 29 1 Example 2c 0.5 0.7 Good 32 31 1 Example 2d 0.4 0.7 Good 24 28 2 Example 2e 0.5 0.6 Good 22 26 0 Example 2f 0.5 0.6 Good 23 27 0Example 2g 0.5 0.7 Good 25 29 0  Comparative Example 2a 0.3 20 Cloudy 22 23 5Comparative Example 2b 0.5 0.6 Good 6 10 28

From Table 4, it can be seen that good results are obtained in Examples 2a to 2g, in particular, as shown in Table 1, the sum of Na + K is 1 to 3 ppm and the sum of Ca + Mg is 25 to 65 ppm.
It can be seen that particularly excellent effects are obtained in Examples 2e to 2g using EVOH 7, 8, 9 in ppm.

[0068]

According to the present invention, an EVOH-based film made of an unstretched or stretched EVOH film having excellent slipperiness, transparency and appearance characteristics is obtained, and its industrial value is great.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 55:00 B29L 7:00 (72) Inventor Hiroki Houan 1000 Mitsubishi, Higashinakaanacho, Ushiku-shi, Ibaraki Pref. (72) Inventor Masashi Hasegawa 1000 Higashikianamachi, Ushiku-shi, Ibaraki F-term (reference) 4F071 AA15X AA29X AA78 AB18 AB26 AB30 AE11 AF30 AF58 AH01 AH04 AH05 BB07 BB08 BC01 4F210 AA19 AB16 AB17 AE01 AG01 AR06 QA02 QA03 QC05 QC06 QD16 QG01 QG18 QW07 4J002 BB201 BB221 BE021 BN031 DB016 DE096 DE146 DE236 DF016 DG046 DJ006 DJ016 DJ036 DJ046 DJ056 DK006 FD176 GA01 GF00 GG01GG02

Claims (5)

[Claims] An unstretched or stretched film of a saponified ethylene-vinyl acetate copolymer containing inorganic particles, wherein the average particle size of the inorganic particles is 1 μm or more and 0.5 times or less the film thickness, and A saponified ethylene-vinyl acetate copolymer film, wherein the content of the inorganic particles in the film is 30 to 5000 ppm. 2. The film according to claim 1, wherein the inorganic particles are particles of an inorganic oxide. 3. The sum of the metal contents of Na and K contained in the saponified ethylene-vinyl acetate copolymer is 0.01 to 50 pp.
The film according to claim 1, which is m. 4. The sum of the metal contents of Na and K contained in a saponified ethylene-vinyl acetate copolymer is 0.01 to 50 pp.
m, and the sum of the metal contents of Ca and Mg contained in the saponified ethylene-vinyl acetate copolymer is from 1 to 20.
The film according to claim 3, wherein the content of Ca is 0 ppm, and the metal content of Ca is 100 ppm or less and the content of Mg is 100 ppm or less. 5. An unstretched film of a saponified ethylene-vinyl acetate copolymer containing inorganic particles is biaxially stretched,
In order to obtain a biaxially stretched film in which the average particle size of the inorganic particles is 1 μm or more, 0.5 times or less the film thickness after biaxial stretching, and the content of the inorganic particles in the film satisfies the condition of 30 to 5000 ppm. The unstretched film is heated at a temperature of 50 to 70 by a roll stretching machine.
° C and a stretching ratio of 2.5 to 4.0 times in the longitudinal direction to obtain a uniaxially stretched film under the condition of a stretching ratio of 2.5 to 4.0 times. A transverse stretching step in which a biaxially stretched film is obtained by stretching in the transverse direction under conditions of 2.5 to 5.0 times, and the obtained biaxially stretched film is subjected to a temperature condition from 110 ° C to a temperature 5 ° C lower than the melting point of the raw resin. A method for producing a saponified ethylene-vinyl acetate copolymer film, which comprises performing a heat-setting step of heat-setting.