JP2000007794A - Molded product formed from saponification product of ethylene-vinyl acetate copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded product formed from a saponification product of an ethylene-vinyl acetate copolymer (EVOH) that is excellent in appearance with few fish eyes or the like and also excellent in transparency and useful for a film, a sheet, a tube, a bag, a container or the like for packaging by limiting a percentage of area of spots generated upon dyeing the surface of the saponification product of the ethylene-vinyl acetate copolymer with an iodine to not more than a specified value. SOLUTION: A percentage of area of spots is limited to not more than 40%. In the production of the molded product (a laminate), it s preferable to carry out a molding under the condition which satisfies the formula: M>=0.295×V0.177 (wherein the unit of V is m/min; and the unit of M is g) in the relationship between a take-off speed (V) of a casting roll and a melt tension (M). As EVOH, though it is not particularly limited, one having an ethylene content of 20-60 mol.% and a degree of saponification of not less than 90 mol.% is preferable. It is also preferable that EVOH has a melt index of 0.5-100 g/10 min and that 1-300 ppm of a sodium metal salt is incorporated thereinto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded product of a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH), and more particularly, to a molded product such as a laminate having excellent appearance and transparency. It relates to a molded product of EVOH.

[0002]

2. Description of the Related Art In general, EVOH is excellent in transparency, gas barrier property, fragrance retention, solvent resistance, oil resistance and the like. It is used after being formed into materials, films and sheets of packaging materials for agricultural chemicals, containers such as bottles, and the like. In such molding, usually, melt molding is performed, and by such molding, it is processed into a shape such as a film shape, a sheet shape, a bottle shape, a cup shape, a tube shape, a pipe shape, and provided for practical use. In order to impart moisture resistance, heat sealability, and the like, it is often used as a laminate by laminating with a base material such as a polyolefin-based resin, and when producing such a laminate, a molded product (laminate) (Molds without fish eyes or stripes) and transparency must be sufficiently satisfied. As one of such measures, it has been proposed to incorporate a boron compound into EVOH (JP-A-59-192564, JP-A-55-12108, and JP-B-49-20615).

[0003]

However, although the method of adding these boron compounds is effective in reducing fish eyes and streaks, depending on the drying conditions of the pellets during the production of EVOH pellets, the addition of these boron compounds is not possible. A molded product such as a film produced using such pellets, in which the boron compound bleeds out, may cause fish eyes or the like to impair the appearance of the film, and improvement is desired.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
In light of this situation, as a result of intensive research, ethylene-
EVOH having an area ratio of spots generated when the surface of a saponified vinyl acetate copolymer is stained with iodine of 40% or less.
The present inventors have found that the molded article can solve the above-mentioned problems, and have completed the present invention. The molded product of the present invention has good transparency, has little fish-eye and surface irregularities, and has a beautiful surface.As a comprehensive measure that satisfies all of these various physical properties, the dyed spots on the molded product surface It is specified by the concept. In obtaining such a molded product (laminate), it is preferable that the molding is performed under the condition that the take-up speed (V) of the casting roll and the melt tension (M) satisfy the following expression (1).
The length of the orifice when measuring the melt tension is 10
mm and the inner diameter is 1 mm.

## EQU2 ## where M ≧ 0.295 × V ^0.177 (1) where V: take-up speed (m / min) M: melt tension (g)

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The molded product of the EVOH of the present invention is characterized most by the fact that the area ratio of spots generated when the surface thereof is subjected to iodine dyeing is 40% or less. When such spots are present at an area ratio of 40% or less, it is preferable that the area ratio of spots having a diameter of 1 mm or less in the area is 35% or more. If the former area ratio exceeds 40%, the object of the present invention cannot be achieved. The area ratio of spots generated when the surface is subjected to iodine staining refers to the surface of a molded product (a single-layer film of EVOH, a laminate having an EVOH layer as an outermost layer or an innermost layer, a tube, a bottle, a tank, etc.). It means the area ratio (ratio per unit area) of spots generated by staining with commercially available iodine tincture. There is no particular limitation on obtaining an EVOH molded product that satisfies such conditions, but in obtaining such a molded product (laminate), the take-up speed (V) of the casting roll and the melt tension (M) satisfy the following formula (1). It can be obtained by molding under satisfactory conditions.

## EQU3 ## M ≧ 0.295 × V ^0.177 (1) where V: take-up speed (m / min) M: melt tension (g)

Hereinafter, the above-mentioned molding method will be described in detail. The EVOH to be used is not particularly limited, but has an ethylene content of 20 to 60 mol% (furthermore, 25 to 60 mol%).
55 mol%), the degree of saponification is 90 mol% or more (furthermore, 95 mol%).
If the ethylene content is less than 20 mol%, the gas barrier properties and melt moldability at high humidity decrease, and if it exceeds 60 mol%, sufficient gas barrier properties are obtained. If the degree of saponification is less than 90 mol%, the gas barrier properties, thermal stability, moisture resistance, etc. are undesirably reduced. EVOH has a melt index (MI) (210 ° C., load 2160 g) of 0.5 to 10;
The melt index is preferably 0 g / 10 min (more preferably 1 to 50 g / 10 min). When the melt index is smaller than the above range, the inside of the extruder is in a high torque state at the time of molding, and the extrusion becomes difficult. If it is larger than the range,
It is not preferable because the mechanical strength of the molded product is insufficient or the film forming property is reduced.

The EVOH is obtained by saponifying an ethylene-vinyl acetate copolymer. The ethylene-vinyl acetate copolymer can be produced by any known polymerization method, for example, suspension polymerization, emulsion polymerization, solution polymerization. Manufactured by
Saponification of the ethylene-vinyl acetate copolymer can also be performed by a known method. If the EVOH is used in a small amount, it may contain other comonomers such as α-olefin, unsaturated carboxylic acid compound, unsaturated sulfonic acid compound, (meth) acrylonitrile, (meth) acrylamide, vinyl ether, vinyl silane compound, vinyl chloride, and styrene. And may be "copolymerized". Also, "post-modified" such as urethanization, acetalization, and cyanoethylation may be used as long as the gist of the present invention is not impaired.

In the present invention, the EVOH
It is also preferable to contain a sodium metal salt, the content of which is 1 to 300 ppm (more preferably 1 to 250 ppm).
When the content is less than 1 ppm, the interlayer adhesion when the laminate is formed is insufficient, and the thermal stability is lowered. On the other hand, when the content exceeds 300 ppm, coloring and thermal decomposition are liable to occur, and Occasionally, streaks and the like often occur, which is not preferable. Examples of such sodium metal salts include sodium acetate, sodium borate (sodium metaborate,
Sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc.), sodium phosphate (sodium dihydrogen phosphate, disodium hydrogen phosphate, etc.), sodium carbonate, hydrogen carbonate Sodium and the like can be mentioned, and preferably, sodium acetate, sodium metaborate, and sodium dihydrogen phosphate are used. If necessary, additives such as a plasticizer, a heat stabilizer, an ultraviolet absorber, an antioxidant, a coloring agent, an antibacterial agent, a filler, and other resins can be used. In particular, a hydrotalcite-based compound, a hindered phenol-based, a hindered amine-based heat stabilizer, and a metal salt of a higher aliphatic carboxylic acid can also be added as a gel generation inhibitor. Further, as the EVOH, it is possible to use two or more different EVOHs. In this case, a blend of EVOH having an ethylene content different by 5 mol% or more and / or a saponification degree different by 1 mol% or more is used. The use is useful because the stretchability at the time of high stretch and the secondary workability such as vacuum pressure forming and deep drawing are further improved while maintaining the gas barrier property. In molding EVOH, melt molding is usually performed, and as such a melt molding method, an extrusion molding method (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.) and an injection molding method are mainly used. The extrusion molding method (T-die extrusion) will be specifically described below, but is not limited thereto.

[0009] EVOH as described above (biaxial or uniaxial)
It is supplied to an extruder, heated and melted and extruded.
The melt molding temperature at this time is selected from the range of about 160 to 250 ° C. The heated and melted EVOH has a T
-EVO extruded from a die and wound on a roll
In the present invention, the relationship between the melt tension (M) and the take-up speed (V) of the casting roll at the melt molding temperature (T-die temperature) is defined by the above ( When the formula (1) is satisfied, the desired molded product of the present invention can be obtained. The thus obtained EVOH single-layer film of the present invention can be used for various applications as it is, but is usually laminated with another resin or the like and often used as a laminate, and is usually used as an organic titanium film. The laminate is obtained by laminating via a known adhesive such as a compound, an isocyanate compound, a polyester-based compound, and a polyurethane compound.

Further, the EVOH of the present invention is obtained by a co-extrusion method.
It is also useful to obtain a molded product. In the case where EVOH is co-extruded with another resin, the molding conditions such as temperature, casting roll take-off speed, etc. should be set so that the EVOH satisfies the above conditions. I just need. Such other resins include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, and ethylene-acrylate copolymer. Unsaturated copolymer, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, homo- or copolymer of olefin such as polybutene, polypentene, or homo- or copolymer of these olefins Polyolefin resins in a broad sense such as those graft-modified with carboxylic acids or esters thereof, polyesters, polyamides, copolymerized polyamides, polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins,
Vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, EVOH, and the like. Among the above, polypropylene, polyamide, polyethylene, ethylene-vinyl acetate copolymer, polystyrene, polyethylene terephthalate, etc. are preferably used from the viewpoint of ease of coextrusion film formation and practicality of film physical properties (particularly strength).

The shape of the laminate may be any shape, and examples thereof include a film, a sheet, a tape, a bottle, a pipe, a filament, and an extrudate having a modified cross section.
Also, the obtained laminate may be subjected to heat treatment, cooling treatment,
Rolling processing, printing processing, dry laminating processing, solution or melt coating processing, bag making processing, deep drawing processing, box processing, tube processing, split processing, and the like can be performed. Films, sheets or containers obtained as described above are foods,
It is useful as various packaging materials for pharmaceuticals, industrial chemicals, agricultural chemicals and the like.

[0012]

The present invention will be specifically described below with reference to examples. In the examples, “parts” and “%” are based on weight unless otherwise specified. Example 1 Ethylene content 35 mol%, degree of saponification 99.8 mol%,
MI 3 g / 10 min (210 ° C., load 2160 g), sodium (in terms of metal) content 98 ppm (sodium was determined by dissolving EVOH in an aqueous solution of hydrochloric acid after incineration and measured by atomic absorption analysis. The same applies hereinafter). It is supplied to a screw extruder, the temperature of the T-die is set at 230 ° C., and the take-up speed (V) of the casting roll is 20 m.
/ Min, and an EVOH film was formed.
The EVOH has a melt tension (M) of 0.9 g.
(Measured with “Capillograph 1C” manufactured by Toyo Seiki Co., Ltd. under the conditions of 230 ° C. and a take-up speed of 20 m / min), which satisfies the above-mentioned formula (1). Performed iodine dyeing with Kenei Pharmaceutical Co., Ltd.
Observed with a 2x video microwatcher, 1
Approximately 85 spots were observed in cm ^2, and the area ratio of the spots was determined by taking a photograph and examining the area ratio of the spots. The area ratio of spots having a diameter of 1 mm or less in the area was 9%.
2%. The evaluation of the obtained EVOH film was performed as follows.

(Appearance) The above EVOH film (10
(cm × 10 cm), the appearance of streaks was visually observed and evaluated as follows. ○ −−− No streaks were observed. △ −−− Slight streaks were observed, but there was no problem in practical use. × −−− Many streaks occurred, making practical use impossible.

(Transparency) The haze value (%) of the above EVOH film was measured with a haze meter and evaluated as follows. ○ --- less than 1% △ --- less than 1-3% × --- 3% or more

Example 2 In Example 1, the ethylene content was 44 mol%, the saponification degree was 99.8 mol%, the MI was 3 g / 10 min (210 ° C., the load was 2160 g), and the sodium (metal equivalent) content was 72 pp.
m EVOH, and the temperature of the T-die is set to 200
An EVOH film was obtained in the same manner except that the temperature was changed to ° C. The EVOH has a melt tension (M) of 1.
9 g (measured with “Capillograph 1C” manufactured by Toyo Seiki Co., Ltd. under the conditions of 210 ° C. and a take-off speed of 20 m / min) satisfying the above-mentioned formula (1), and the surface of the obtained EVOH film was prepared in Example 1. 1cm
² , approximately 45 spots were observed, the area ratio of the spots was 13%, and the area ratio of spots having a diameter of 1 mm or less in the area was 98%. The obtained EVOH film was evaluated in the same manner as in Example 1.

Example 3 In Example 1, the content of ethylene was 44 mol%, and saponification was carried out.
99.8 mol%, MI 12 g / 10 min (210 ° C, load
Weight 2160g), sodium (metal equivalent) content 68p
pm EVOH and the T-die temperature was set to 19
Except that the temperature was changed to 0 ° C, the same procedure was followed to obtain an EVOH film.
I got The melt tension (M) of the EVOH is
0.7g (at 190 ° C, take-off speed 20m / min)
Measured with "Toyo Seiki Co., Ltd." Capillograph 1C ")
Which satisfies the above equation (1), and the obtained EV
When the surface of the OH film was examined in the same manner as in Example 1,
1cm ^TwoApproximately 124 spots were observed on the spots.
Area ratio is 34%, and the diameter occupying the area is 1%.
The area ratio of the spots of mm or less was 62%. E obtained
The VOH film was evaluated in the same manner as in Example 1.
Was.

Example 4 EVOH was carried out in the same manner as in Example 1 except that the temperature of the T-die was changed to 210 ° C., and the take-up speed (V) of the casting roll was changed to 50 m / min.
A film was obtained. The melt tension (M) of the EVOH was 3.9 g (210 ° C., take-off speed 50 m / m
(measured with “Capillograph 1C” manufactured by Toyo Seiki Co., Ltd. under the conditions of “in”), which satisfied the above expression (1). The surface of the obtained EVOH film was examined in the same manner as in Example 1 to find 1 cm ² And 17 percent of the spots were observed. The area ratio of the spots was 8%, and the area ratio of spots having a diameter of 1 mm or less in the area was 95%. The obtained EVOH film was evaluated in the same manner as in Example 1.

Example 5 In Example 1, the ethylene content was 44 mol%, the saponification degree was 99.8 mol%, the MI was 12 g / 10 min (210 ° C., the load was 2160 g), and the sodium (metal conversion) content was 253.
ppm EVOH and the T-die temperature was 2
An EVOH film was obtained in the same manner except that the temperature was changed to 00 ° C., and the take-up speed (V) of the casting roll was changed to 50 m / min. The EVOH has a melt tension (M) of 0.6 g (measured at 200 ° C. under a condition of a take-up speed of 50 m / min with “Capillograph 1C” manufactured by Toyo Seiki Co., Ltd.), which satisfies the above formula (1). When the surface of the obtained EVOH film was examined in the same manner as in Example 1, about 137 spots were observed in 1 cm ² , the area ratio of the spots was 35%, and the diameter occupying the area was 35%. The area ratio of spots of 1 mm or less was 53%. About the obtained EVOH film, Example 1
The evaluation was performed in the same manner as described above.

Example 6 Ethylene content 35 mol%, degree of saponification 99.8 mol%,
EVOH, LD with MI 3g / 10 min (210 ° C, load 2160g), sodium (metal conversion) content 98ppm
PE (manufactured by Nippon Polychem, "LF542H") and adhesive resin (manufactured by Mitsui Petrochemical Industries, "Admer LF50"
0 ”) to a three-type three-layer co-extruder, the temperature of the T-die is set to 210 ° C., and the take-up speed (V) of the casting roll is set to 20 m / min.
An H stack (EVOH / adhesive resin / LDPE) was formed. The melt tension (M) of the EVOH was 1.5 g (measured with “Capillograph 1C” manufactured by Toyo Seiki Co., Ltd. under the conditions of 210 ° C. and a take-up speed of 20 m / min).
Which satisfies the above equation (1), and the obtained EV
When the surface of the OH film was examined in the same manner as in Example 1,
About 74 spots are observed in 1 cm ² , the area ratio of the spots is 25%, and the diameter in the area is 1 m.
The area ratio of spots of m or less was 95%. EV obtained
The OH laminate was evaluated in the same manner as in Example 1.

Comparative Example 1 In Example 1, the ethylene content was 35 mol%, the saponification degree was 99.8 mol%, the MI was 12 g / 10 min (210 ° C., the load was 2160 g), and the sodium (metal equivalent) content was 91 p.
pm EVOH, and the T-die temperature was changed to 21
The procedure was the same except that the temperature was set to 0 ° C. and the take-up speed (V) of the casting roll was changed to 20 m / min, but the melt tension (M) of the EVOH was 0.3.
g (measured with “Capillograph 1C” manufactured by Toyo Seiki Co., Ltd. under the conditions of 210 ° C. and a take-up speed of 20 m / min), the formula (1) was not satisfied, and the obtained EV was not satisfied.
When the surface of the OH film was examined in the same manner as in Example 1,
Many large spots having a diameter of 1 mm or more were observed in 1 cm ^2, and the area ratio of the spots was 63%. The obtained EVOH laminate was evaluated in the same manner as in Example 1. Table 1 shows the evaluation results of the examples and comparative examples.

[0021]

[Table 1]

[0022]

According to the present invention, the EVOH molded product has less fish eyes and the like, is excellent in appearance and excellent in transparency, and is used for packaging films, sheets, tubes, foods, pharmaceuticals, agricultural chemicals and industrial chemicals. It is very useful for applications such as bags and containers, and can be suitably used particularly for secondary processed products involving stretching.

Continued on the front page F-term (reference) 4F071 AA15X AA28X AA78X AF30 AH04 BA01 BB06 BC01 BC10 4F100 AK69A AT00B BA02 BA10A BA10B EJ37 GB01 GB15 GB16 GB23 GB66 JA20A JN01 YY00A 4F207 AA10J AD05 AG01 AG03 002 001 001 GG01 GG02

Claims (5)

[Claims] 1. Molding of a saponified ethylene-vinyl acetate copolymer, wherein the area ratio of spots generated when the surface of the saponified ethylene-vinyl acetate copolymer is stained with iodine is 40% or less. object. 2. The area ratio of spots generated when the surface of a saponified ethylene-vinyl acetate copolymer is stained with iodine is 40% or less, and the area ratio of spots having a diameter of 1 mm or less occupying the area is reduced. The molded product of the saponified ethylene-vinyl acetate copolymer according to claim 1, wherein the amount is 35% or more. 3. The ethylene-vinyl acetate copolymer according to claim 1, wherein the casting roll has a take-up speed (V) and a melt tension (M) which are formed under conditions satisfying the following formula (1). Molded product of saponified polymer. [Number 1] ^{M ≧ 0.295 × V 0.177 ··· (} 1) where, V: take-off speed (m / min) M: melt tension (g) (Note that the speed melt tension take-off during the molding temperature (V ), The orifice length at this time is 10 mm and the inner diameter is 1 mm) 4. The saponified ethylene-vinyl acetate copolymer according to claim 1, wherein the content of the sodium metal salt in the saponified ethylene-vinyl acetate copolymer is 1 to 300 ppm. Molded product. 5. The saponified ethylene-vinyl acetate copolymer according to claim 1, wherein the outermost layer or the innermost layer is a laminate having a saponified ethylene-vinyl acetate copolymer. Moldings.