JPS625832A - Manufacture of molded product of ethylene-vinyl alcohol and multi-layer structure - Google Patents

Abstract

PURPOSE:To prevent generation of crack, pinhole, local ununiform thickness or the like and obtain high gas barrier property by a method wherein moisture content is regulated within a given range upon heating and orienting the molded product of ethylene-vinyl alcohol copolymer in which the ethylene-vinyl alcohol copolymer of specified composition is blended with the specified amount of long chain aliphatic series or aromatic series amide. CONSTITUTION:When the molded product of ethylene-vinyl alcohol copolymer (EVOH), in which 100wt. parts of EVOH having 20-60 mol % of ethylene content and 90% or more of degree of saponification is blended with 0.5-5wt. parts of long chain aliphatic series or aromatic series amide, the moisture content of said molded product is controlled to 0.1-5wt.% with respect to the wt.% of EVOH. When the content of ethylene becomes lower than 20mol%, molding temperature becomes near to the decomposition temperature thereof and molding becomes difficult. On the other hand, when the content of ethylene becomes higher than 60mol%, the gas barrier properties are deteriorated and the gas barrier properties of said multilayer constitution vessel becomes unsatisfactory, therefore, it is not preferable. Further, the melt index (MI) of the EVOH, which is measured at 190 deg.C under ASTM-D1238-65T, may be 0.1-25g/10min and preferably 0.3-20g/10min.

Description

DETAILED DESCRIPTION OF THE INVENTION 11. Industrial Application Fields The present invention is free from pinholes, cracks, localized thickness deviations, etc., and has excellent gas barrier properties. The present invention relates to a method for manufacturing an ethylene-vinyl alcohol co-M combination (hereinafter referred to as EVOH) molded product and a method for manufacturing a multilayer structure.

B. Prior Art EVOH is now recognized to have considerable value in food packaging films, particularly those intended for use with food and other products requiring protection against oxygen. however.

A single-layer film made of EVOH lacks toughness and is brittle, and this film has drawbacks such as a decrease in gas barrier properties due to water or water vapor.

In order to improve these drawbacks, EVOH resins are usually composed of a structural layer containing one or more thermoplastic resins such as nylon, polyester, polypropylene, polyethylene, or polyvinyl chloride, and an ionomer or ethylene vinyl acetate copolymer. It is used in the form of a multilayer film formed by laminating various types of heat sealant layers such as .

By the way, when secondary processing a multilayer film, sheet, parison, etc. manufactured by coextrusion, extrusion lamination, dry lamination, solution coating method, etc. as a packaging container, EVOHL: When performing stretch molding at a temperature below the melting point of EVOHL:D. ,gV
Small voids, cracks, local thickness unevenness, etc. occur in OHi. As a result, the oxygen barrier properties of these molded products, which are characterized by their high oxygen barrier properties, have been significantly reduced, and their transparency has deteriorated in appearance, making it difficult to use them as packaging containers. .

Therefore, as a countermeasure to prevent pinholes, cranks, localized thickness unevenness, etc. in the EVOH layer that occur during container molding processing, blending of polyamide resin with EVOH and aromatic sulfonamide plasticizer (JP-A-59 ~2034
5) Mixtures of glycerin, various i-glycols, hydroxyl group-containing plasticizers such as polyhydric compounds (Japanese Unexamined Patent Publication No. 53-88067), etc. are currently under consideration, but in any case, the following It turned out that the results were not completely satisfactory. That is, when polyamide resin is blended with EVOH polymer to obtain a multilayer structure, the polyamide resin and EVOH react.

A large number of gel-like substances (fish eyes) are generated in the molded product, and the product is so discolored that it becomes unusable.

In addition, if the multilayer structure is made into a container by secondary molding, then EVO
In order to completely prevent the occurrence of cracks, pinholes, etc. in the H layer, it is necessary to add the polyamide resin in a large amount of 10 to 30 parts by weight per 100 parts by weight of EVO, H. As a result, the gas barrier properties are greatly reduced, and even if the molded containers are good, they cannot be used in the food packaging field, which is characterized by high gas barrier properties.

Also, in hydroxyl group-containing plasticizer systems, the amount added is
Similar to polyamide resins, it is necessary to use 10 to 20 parts by weight per part by weight, and the gas barrier properties are greatly reduced. To make matters worse, perhaps because the compatibility with EVOH is not sufficient, the plasticizer bleeds, and the adhesive strength between the EVOH layer and other resin layers in multilayer laminated containers decreases significantly over time, causing the shape of the container to deteriorate. disturb one's condition. In other words, the above additives are unacceptable to use.

Therefore, it is an important issue to develop EVOH that has good moldability, without causing a large decrease in gas barrier properties, and without causing pinholes, cracks, minute thickness deviations, etc. in the EVOH layer during container molding in multilayer structures. There is one.

C1 Problems to be Solved by the Invention Although EVOHFi has excellent properties as described above, when the laminate with thermoplastic resin is secondary processed into containers etc., the EVOH layer may have cracks, pinholes, localized As a result, the barrier properties of EVOH multilayer containers, which are characterized by high gas barrier properties, are significantly deteriorated due to uneven thickness.

Therefore, the present inventors have developed a method to prevent cracks, pinholes, local thickness unevenness, etc. in the EVOH layer that occur when secondary processing a laminate into containers, etc., without impairing the excellent gas barrier properties of EVOH. EVO with gas barrier properties
As a result of intensive studies to develop EVOH for multilayer containers, we have completed the present invention.

The present invention has an ethylene content of 20 to 60 mol% and a saponification degree of 90.
% or more of EVO) I and 0.5 to 5 parts by weight of a long-chain aliphatic or aromatic amide is heated and stretched when the moisture content in the molded product is reduced to 0.1. A method for producing an EVOH molded product characterized by adjusting the EVOI to ~5% by weight (weight% relative to EVOI), and E
When heating and stretching a laminate having a thermoplastic resin layer on at least one side of an EVOH composition layer containing 100 parts by weight of VOH and 0.5 to 5 parts by weight of a long-chain aliphatic or aromatic amide, in the EVOH composition layer. Moisture content of 0.1~
This is a method for producing a multilayer structure characterized by adjusting the content to 5% by weight.

E1 Function and effect of the invention EVOI (various sheets and parisons having a thermoplastic resin layer on one or both sides of the layer via an adhesive resin are prepared and then secondary processed into cups and bottles by reheating and stretching operations. It is possible to judge the moldability and gas barrier properties of the EVOH layer by measuring the appearance and gas barrier properties of the container.The present inventors blended various plasticizers, polymers, etc. with EVOH. The molding processability and gas barrier properties of EVOH were measured.As a result, long-chain aliphatic or aromatic amide compounds, especially sulfonamide compounds were blended, and 7'HEVOH was composed of single EVOH and other plasticizers. E blended with polymer etc.
Although it has good properties compared to VOH compositions, E V
Pinhole 1 in OH layer It is not possible to completely prevent the occurrence of cracks and minute thickness deviations, and gas barrier properties are not always sufficient.

Furthermore, the reproducibility was also insufficient. However, surprisingly, by adjusting the moisture content to a predetermined value when heating and stretching the E-VOR molded product in which the amide compound was blended with EVO) I, .

Not only can a very good molded product with good reproducibility and almost no pinholes, cracks, or minute thickness deviations in the EVOH layer during container molding be obtained, but the gas barrier properties of the molded product are additive-free.
The present invention was based on the fact that a container with very good barrier properties, which is almost the same as that of VOH, can be obtained.

By the way, while the higher the crystallinity of EVOI (the better the gas barrier properties are), it is thought that cracks, pinholes, minute thickness deviations, etc. are more likely to occur in the EVOH layer during container molding.The cause is not obvious. However, long-chain aliphatic or aromatic amide compound @EVOH acts as a softener at high temperatures due to the synergistic effect of moisture and the amide compound.
While preventing the occurrence of cracks in the EVOH layer, at room temperature, long-chain fatty acid amides or aromatic amides with large hydrophobic groups reduce the interaction between moisture and EVOH, and the EVOH
It is thought that the degree of crystallinity of OH increases, and as a result, the barrier properties become better, with no significant difference from that of EVO (without additives).

A more detailed explanation of the F1 invention The present invention will be explained in more detail below.

The EVQH used in the present invention has a 1-functional tyrene content of 20~
60 mol%, preferably 25-55 mol.

The degree of saponification of the vinyl acetate component is 90% or more, preferably 95%.
% or more of ethylene-vinyl acetate co-assembly saponified product.

When the ethylene content is less than 20 moles φ, the molding temperature approaches the decomposition temperature, making molding difficult.

On the other hand, if the ethylene content exceeds 60 mole, the gas barrier properties will be lowered, and the gas barrier properties of the multilayered container will be unsatisfactory, which is not preferable.

In addition, the degree of saponification of the vinyl acetate component is less than 95%.

In particular, if the EVO)I content is less than 90%, it is possible to obtain a product with few or no cracks or pinholes during container molding, but it is not preferable because it has poor barrier properties. Sara K This EVOI
(The melt index (MI) measured at 190°C from [AS TM-D1238-65TK is 0.1 to 25
? /l 0m1n preferably 0.3~201/10m
1n○ Typical long-chain aliphatic amides used in the present invention include long-chain aliphatic carboxylic acid amides and long-chain aliphatic sulfonic acid amides.0 These amide compounds have 10 to 10 carbon atoms. 20 is good. Further, the amide group may have one or two N-substituted alkyl groups (the alkyl group has 1 to 5 carbon atoms). In addition, as carboxylic acid amides, monocarboxylic acid amides, polyvalent (di, tri, etc.)
Carboxylic acid amide is rejected. Specific examples of these include oleic acid amide and stearic acid amide.

Valmitic acid amide, N-ethyl stearic acid amide,
Examples include N, N distearyl ethylene diamide, among which stearic acid amide is particularly preferred.

Oleic acid amide is preferred.

Furthermore, typical aromatic amides used in the present invention include aromatic carboxylic acid amides and aromatic sulfonamides. Further, this amide group may have one or two N-substituted alkyl groups (the alkyl group has 1 to 5 carbon atoms). Specific examples of aromatic carboxylic acid amides include carboxylic acid amides having a mi-te-iophenyl group in the basic skeleton, such as methylbenzoic acid amide and phenylcarboxylic acid amide, and specific examples of aromatic sulfonic acid amides include There is no particular limitation as long as it has a phenyl group as a basic skeleton and a sulfonic acid amide group, such as p-toluenesulfonic acid amide, 0-toluenesulfonic acid amide, N-ethyltoluenesulfonic acid amide, phenyltoluenesulfonic acid amide, Examples include N-stearyl phenylsulfonamide, N-phenyl toluenesulfonamide, etc., and N-ethyl 11enesulfonamide is particularly effective.

Regarding the amount added, if the amount of long-chain aliphatic amide or aromatic amide added is less than 0.5 parts by weight per 100 parts by weight of EVOH, cracks may occur during container molding.

Pinholes, minute thickness deviations, etc. occur, and the barrier properties deteriorate significantly, making it unusable.

On the other hand, the amount of long chain fatty acid amide or aromatic amide added is 5
When the amount is more than 1 part by weight, the occurrence of cracks, pinholes, etc. in the molded product can be suppressed, but the barrier properties are not sufficient, and it is difficult to obtain a product with sufficient adhesive strength. The preferred amount of long-chain aliphatic amide or aromatic amide is 0.6 to 4.9.
If the water content at the time of heating and stretching is less than 0.1% by weight, not only will reproducibility deteriorate, but also cracks, pinholes, etc. will appear during container molding, and gas barrier properties will deteriorate. It cannot withstand use. On the other hand, if the amount of water added is 5% by weight or more, the water in the KEYOH layer will foam during heating and stretching, and the occurrence of cracks, uneven stretching, etc. will become noticeable.
It is also not possible to obtain sufficient ganne barrier properties. A suitable water content is 0.2-3% by weight.

The method of blending the amide compound into E V O'H is not limited to 1%, and the method of blending the amide compound into E V O'H is not limited to 1%. E
Tri-blend to VOIF (banbury mixer 5)
Pelletization using a single-screw or twin-screw vent extruder,
Drying is preferable. At this time, sealing the inside of the extruder hopper and dryer with N2 is effective in preventing coloring and gel formation. On the other hand, each component may be directly supplied to a molding machine and molded while being kneaded by the molding machine. Also when kneading these.

Other additives (various resin antioxidants, plasticizers, colorants, etc.) may be used as long as the effects of the present invention are not impaired. In particular, it is suitable to add 0.01 to 1 part by weight of a hydrotalcite compound or a hindered phenol antioxidant to improve the thermal stability of the resin and to prevent gel formation.

Also regarding the control of moisture content.

Although not particularly limited, the fc method includes a method of using a moisture-containing pellet during molding, or a method of leaving the molded product before heating and stretching in a temperature and humidity controlled room.
Alternatively, there are methods such as short-term contact with hot water, heated water, steam, etc.

Here, heating stretching refers to -axis stretching, biaxial stretching, under conditions that satisfy X-10°C≧Y≧X-110°C (fc stock, Refers to an operation of stretching (simultaneous or sequential). The stretching ratio can be selected as appropriate depending on the purpose, but when obtaining a film-like product, the stretching ratio is 2.0 to 5.0 times in the longitudinal direction in the case of uniaxial stretching, and 2.0 to 5.0 times in the longitudinal direction in the case of biaxial stretching. 2 to 4 times in the direction, 2 to 4 times in the horizontal direction
The area magnification is preferably 4 to 16 times.

The EVOH composition of the present invention can be prepared using well-known melt molding methods.

Although it can be molded into any molded product such as a film, sheet, tube, or bottle by the compression molding method, remarkable features are exhibited when the composition described above is used as a layer of a multilayer structure. Therefore, an explanation regarding this point will be added below.

First, as a method for obtaining a multilayer structure, the EVOH composition and a thermoplastic resin are bonded via an adhesive using extrusion lamination method, dry lamination method, co-extrusion lamination method, co-extrusion lamination method (feed block, multi-manufacturing method). A laminate is obtained by the Hohad method), the coextrusion pipe making method, the co-injecting method, and various solution coating methods.Then, this is placed in a vacuum-pressure deep-drawing molding machine, and an axial stretching blow machine or the like is used to form a laminate within the melting point of pEVOI. Alternatively, the laminate (sheet or film) is subjected to a biaxial stretching machine.

Examples include a method of heating and stretching, and a method of co-injecting and biaxially stretching an EVOH composition and a thermoplastic resin. The adhesive resin used here is not particularly limited as long as it can be stretched and molded at a temperature below the melting point of EVOH.

The thermoplastic resin used here is represented by the following formula, but any resin that can be stretched within the range of hot stretching temperature can be used.

X-10°C≧Y≧X-110°C (fc is the melting point of the ethylene-vinyl alcohol copolymer in °C, and Y is the heating stretching temperature in °C.) As such a thermoplastic resin, polypropylene resin Preferred examples include polystyrene resin, polyamide resin, monosaturated polyester resin, and polyvinyl chloride resin. These thermoplastic resins are used to improve the various disadvantages of EVOH (lack of toughness, brittleness, deterioration of gas barrier properties due to contact with water or steam, etc.).

Please note that the adhesive resin used here is not particularly limited. You can use whatever you have.

Furthermore, there are no particular limitations on the thickness structure of the multilayer structure, but when considering moldability, cost, etc., the EVOH layer thickness ratio to the total thickness is preferably about 2 to 20%. In the present invention, heating As mentioned above, a stretched multilayer structure is a container such as a cup or a bottle, a sheet or a film obtained by heating and stretching.
Thorough heating stretching means that it is carried out within the heating stretching temperature range shown by the above formula. If the heating drawing source f(Y) is below X-110°C, the glass transition temperature (T2) of the thermoplastic resin will be below room temperature, resulting in poor shape stability of the molded product at room temperature and the desired multilayer structure. Can't get structure.

do. Furthermore, heating means to leave the multilayer laminate at the temperature required for heating and stretching for a predetermined period of time, and to operate the multilayer laminate so that it becomes thermally uniform. An operation for uniform heating is also preferred. The heating operation may be performed simultaneously with the stretching or before the stretching.

Stretching refers to the operation of uniformly shaping a thermally uniformly heated multilayer laminate into a container, sheet, or film by using a chuck, plug, vacuum, compressed air, blowing, etc. - Axial stretching, biaxial stretching (same FiFP or sequential) can be used. Further, the stretching ratio can be appropriately selected depending on the purpose.

In addition, the layer structure of the multilayer structure includes EVOH composition layer/
Representative examples include adhesive resin N/thermoplastic resin layer and thermoplastic resin layer/adhesive resin/EV OH composition layer/adhesive resin M/thermoplastic resin layer. When thermoplastic resin layers are provided in both rows, the resins may be different or the same.

The thus obtained heat-stretched multilayer structure of the present invention has no pinholes, cracks, or uneven thickness in the EVOH composition layer, so it has extremely good gas barrier properties and can be used as food packaging containers or gas It is useful as a container that requires barrier properties.

The present invention will be further explained below with reference to Examples, but the present invention is not limited by these in any way.

(EVO) (Method for Measuring Moisture in Layer) The EVOH layer in the multilayer structure immediately before heat-stretching is peeled off and left in a hot air dryer at 120° C. for 24 hours, and the moisture in the EVAL layer is determined from the weight loss.

This value is expressed as a percentage and is referred to as volatile content.Example 1 Ethylene content 31 mol%, degree of saponification 99.4%, tart index (MI190) 1.39/EV of 10 minutes
3 parts by weight of N-ethyltoluenesulfonamide and 1 part by weight of water were blended with too many parts by weight of OH (Kurarayhi EVAL-EP-FIOI), and extruded at 220°C using a twin-screw type vent type 40φ extruder. Pelletization was performed. The obtained pellets were heated at 95°C to remove water adhering to the surface.
- Dry for 16 hours. Using this pellet, a sheet was prepared by applying it to a feed block type 3 type 5 layer coextrusion device.

The structure of the sheet is that the outer layer of both liquids is polypropylene (Noblen MA-5 manufactured by Mitsubishi Yuka Co., Ltd.) of 400 μm each, and the adhesive layer (Mitsubishi Yuka Modic 300 F (maleic anhydride graft modified ethylene-vinyl acetate copolymer)) is 400 μm each. The EVOH layer has a thickness of 50μ, and the innermost thickness (center) is 50μ. The obtained six sorts were heat-formed (SPPP molding) at 155° C. using a vacuum-pressure molding machine, and the volatile content of the EVAL layer before molding was 0.28%.

A well-formed molded product with good transparency and no cracks or slight unevenness in thickness was obtained. The drawing ratio of the molded product was 1.5. This molded container was kept at 20°C, 100% RH, and 65% RH for about 3 months), and a Mocon oxygen analyzer (
As a result of measuring the amount of oxygen permeation using a device (manufactured by Mocon), the amount of oxygen permeation through the EVOH layer was 0.5CC・2.
0μ/n+″i4hr-atm (20℃165%RH)
, 24cC・20t-t/rr!・24hr-a
tm (20°C, 1.0% RH) and showed very good gas barrier properties. Comparative Example 1 In Example 1, the intermediate layer was made of additive-free EVOH (EVAL-
The same procedure as in Example 1 was conducted except that EP-FIOI) was used. When the resulting sheet is vacuum-pressure deep drawn and formed,
Many minute cracks and pinholes were generated on the side of the molded container, so much so that they could be clearly observed with the naked eye.The amount of oxygen permeation through this container was so occ・20μ/rr?・24 hours
-atm (20°C, 100% RH), it was found that the EVOH layer was cut. For reference,
When the oxygen permeation rate of the EVOH layer was measured on the sheet before deep drawing, it was 0.6cc -20tt/m+' ・24h
r-atm (20°C 165% RH), 24cc-2
0μ/ni”-24hr-atm (20℃, 100%R
H).

Comparative Example 2 In Example 1, EVOH (EVAL-EP-
Example 1 was carried out in the same manner as in Example 1, except that a pelletized resin containing 1 part by weight of 15 parts of ether toluene sulfonamide per 1.00 car parts of FIOI was used.

As a result, the appearance of the drawn container was a good molded product with no cracks, etc. However, after 2 to 3 days, the pEVOH layer and adhesive layer began to peel off from the edges of the molded container.
A. Oxygen permeation rate of EVAL layer is 5 to 2 op/m”-:
z4hr atm (2Q'C, 65%RH), 9o
cc・20μ/rtl'・24hratrn(20℃1
65% RH) and poor barrier properties were observed.

Comparative Example 3 In Example 1, EVOH (EVAL-EP
ethyl-toluenesulfonamide to 100 parts by weight of FIOI). The same procedure as in Example 1 was carried out, except that the pelletized resin was vacuum dried at 120° C. for 4 days to sufficiently remove moisture. As a result, cracks and slight thickness deviations were observed in the EVOH layer of the drawn container. When Hata et al. measured the amount of oxygen permeation through the EVOH layer,
200cr-・20μ/rI!・24hr-atm (
(20° C., 165% RH), which was so bad that it could not be used. Further, the volatile content of the EVOH layer immediately before thermoforming was 0.04%.

Comparative Example 4 In Example 1, EVOH (EVAL-EP-
The procedure of Example 1 was repeated except that 1 part by weight of water was mixed with 100 parts by weight of FIOI) and pelletized resin was used. As a result, cracks were observed in the EVOH layer of the drawn container, and the gas barrier properties were also very poor. The volatile content of the EVOH layer before thermoforming at this time was 0.41%.

Example 2 EVOH (y Lale [EVAL-EP-Ftol) 10 with ethylene content 31 mol%, saponification degree 99.4%, melt index (MF 1190°C) 1.3 f/10 min
4 parts by weight of o-toluenesulfonamide and 0.5 parts by weight of water were blended with respect to 0 part by weight, and pelletization, drying, and sheet production were carried out in the same manner as in Example 1.

After that, the sheet was immersed in water at 80°C for 10 minutes.

When container molding was carried out, a molded product with good transparency and no cracks was obtained. In addition, the amount of oxygen permeation through the EVOH layer is o,
scc・20μ/rn”・24hr Hatm (20
℃165℃RH), 29c1. -20μ/rr+”24
hr-atm (20° C., 100% RH), and exhibited excellent gas barrier properties.

Comparative Example 5 The same procedure as in Example 2 was carried out, except that the pellets before film formation were dried under reduced pressure at 120° C. for 4 days and pellets with a volatile content of 0.01% or less were used.

As a result, cracks and uneven thickness were observed in the EVAL layer of the drawn container, and the oxygen permeability of the EVOH layer was 180CQ.
・20μ/rn'・24hr Hatm (20℃565
%RH) and showed poor results. The volatile content of the EVOH layer of this container just before thermoforming is 0.07% (dry paste).

Further, as a result of quantitative determination by NMR method, it was found that 0-toluenesulfonamide was 3.6% (dry basis).

Example 3 In Example 1, the outermost polypropylene layer was made of polystyrene (Idemitsu Kosan Chistyrene ET-61), and the adhesive layer was made of Toyo Soda (Mersene M5420) (maleic anhydride graft modified ethylene-vinyl acetate copolymer). Example 1 except that the vacuum pressure forming temperature was changed to 120°C.
I went to the same iK.

As a result, a good molded product with no cracks etc. was obtained, and the oxygen barrier properties of the EVOH layer also showed very good results. Its oxygen permeability is 0.6CC/20μ/
&-24hr-atrn (20°C, 65%RH), 24
CC-20μ/m'・24hr-atm (20°G,
9 i at 100% RH).

Example 4 Ethylene content: 38 moles, saponification degree: 99.4%.

Melt index 1.4 r/l 0 min EVOI (
3 parts by weight of N-ethyltoluenesulfonamide and 1 part by weight of water were blended with 100 parts by weight of EVAL-EP-HIO1 (manufactured by Kuraray), and extrusion pelletization was carried out using a 40φ screw extruder. The obtained pellet was 105
After drying with hot air for 6 hours at ℃, spiral flow type 3
A coextruded pipe was made using a woodcutter 5-layer coextrusion pipe forming machine. The structure of the pipe is that the outermost and innermost layers are made of polyester (
PET-G9921 Eastman Chemical) 2000
An adhesive resin (Mersen M5420 manufactured by Toyo 1 Co., Ltd.) of 200 μm each was interposed between the μ layer and the EVOH intermediate layer of 200 μm. The obtained pipe was formed into a parison for biaxial stretch blow molding at both ends, then put into a biaxial stretch blow molding machine, preheated at 105°C, and then biaxially stretched and blown to produce a good bottle with no cracks or slight thickness deviation. Obtained. The volatile content of the EVAL layer immediately before thermoforming was 0.25%. Oxygen permeation through the EVOH layer of this container is 1.1CC・20μ/
n? -24hr -atm (20℃, 65℃RH),
21CC・20μ/nl-24hr・atm(20℃
, 100% RH), showing good barrier properties.

Comparative Example 6 In Example 4, additive-free EVOH (EVAL
The same procedure as in Example 4 was conducted except that EP-HIOI) was used. As a result, the biaxially stretched blow container had a slight unevenness in thickness at the bottom and near the mouthpiece (shoulder), resulting in poor appearance.

Example 5 In Example 1, the outermost polypropylene layer and adhesive layer were made of nylon 6.66 copolymer (Mitsubishi Kasei (Tsubamide)).
Novamid 2030) The sheets obtained by changing the thickness to 500μ each were immersed in hot water at 80°C for 20 minutes, and then biaxially stretched 3x3 times at 110°C simultaneously using a biaxial stretching tester (manufactured by Toyo Seiki). As a result, a homogeneous multilayer biaxially oriented film was obtained. At this time, the volatile content of the EVOH layer immediately before thermoforming was 2.3%.

Comparative Example 7 In Example 5, the intermediate layer was made of additive-free EVOH (EVAL
The same procedure as in Example 4 was performed except for f using EP-FIOI). The resulting film had localized unevenness and was poor in appearance.

Example 6 3 parts by weight of steric acid amide was blended with 100 weight S of EVOH (EVAL-EP-E105 manufactured by Kuraray) having an ethylene content of 44 mol%, a degree of saponification of 99.4%, and a melt index of 5.6 P/10 minutes. The resulting mixture was extruded into pellets at 220°C using a twin screw vent type 40φ extruder. The obtained pellets were heated to 105℃-16
After drying with hot air for several hours, a 100μ single-layer film was obtained using a 40φ extruder with a T-die. This film was sequentially biaxially stretched using a biaxial stretching tester (Toyo Seiki! B), and a good stretched film was obtained. was gotten. The stretching temperature was 80°C, and the volatile content of the film immediately before stretching was 0.25%.

Comparative Example 8 The same procedure as in Example 6 was conducted except that EVOH (EVAL-EP-E105 manufactured by Kuraray) containing no additives was used. As a result, the film was torn during sequential biaxial stretching, and a normal film could not be obtained. The stretching temperature was 80° C. The volatile content of the film immediately before the first stretching was 0.32%.

Example 7 LiBr-containing EVO used in Example 6) 1200 t,
The adhesive used for dry laminating the t film on 1000 μm vinyl chloride is Toyo Morton AT-335.
A (polyester adhesive) was used. Next, the sheet was thermoformed at 120°C using a vacuum pressure deep drawing machine, and the sheet was drawn at 90°C.
When a comparative container was made, a good-looking molded product with no cracks was obtained.The volatile content of the EVOH layer immediately before thermoforming was 0.5%.
Met.

Claims (6)

[Claims] (1) Ethylene content 20-60 mol%, saponification degree 90
% or more of ethylene-vinyl alcohol and 0.5 to 5 parts by weight of a long-chain aliphatic or aromatic amide is heated and stretched. A method for producing an ethylene-vinyl alcohol copolymer molded article, characterized in that the content is adjusted to 0.1 to 5% by weight. (2) The composition according to claim 1, wherein the long-chain aliphatic amide is a mono- or dicarboxylic acid amide having 10 to 20 carbon atoms. (3) The composition according to claim 1, wherein the aromatic amide is an aromatic carboxylic acid amide. (4) The composition according to claim 1, wherein the aromatic amide is an aromatic sulfonic acid amide. (5) Ethylene content 20-60 mol%, saponification degree 90
% or more of ethylene-vinyl alcohol copolymer and 0.5 to 5 parts by weight of a long-chain aliphatic or aromatic amide, a thermoplastic resin layer is provided on at least one side of the ethylene-vinyl alcohol copolymer composition layer. A method for producing a multilayer structure, which comprises adjusting the water content in the ethylene-vinyl alcohol copolymer composition layer to 0.1 to 5% by weight when heating and stretching the laminate comprising the ethylene-vinyl alcohol copolymer composition layer. (6) The heat-stretched multilayer structure according to claim 5, wherein the thermoplastic resin can be stretched within the range of the heat-stretching temperature represented by the following formula: X-10°C≧Y≧X-110°C (However, X indicates the melting point of the ethylene-vinyl alcohol copolymer in °C, and Y indicates the heating stretching temperature in °C.)