JPS61290047A - Gas barriering multilayer structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] A. Industrial Field of Application The present invention provides a gas that is free from thickness unevenness, streaks, etc. during coextrusion molding, and free from pinholes, cracks, and local thickness unevenness during heating stretching. It relates to a multilayer structure with excellent barrier properties, and is particularly suitable for food packaging.

B. Prior art saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH)
are now recognized as being of considerable value in food packaging films, particularly those intended for use with food and other products requiring protection against oxygen. However, single-layer films made from EVOH lack strength and are brittle, and the films do not exhibit effective barrier properties against water or water vapor.

To improve these drawbacks, EVOH resins are usually made of nylon, polyester, polypropylene, polyethylene,
It is a multilayer film made by laminating a structural layer containing one or more thermoplastic resins such as polyvinyl chloride, and various heat sealant layers such as ionomers and ethylene-vinyl acetate copolymers. It is used.

By the way, due to recent technological advances, multilayer structures containing EVOH are often produced using coextrusion molding methods, in which multiple extruders simultaneously extrude various resins and a single die produces a multilayer laminate. .

Further, in order to increase the strength of the multilayer structure, heating and co-stretching may be performed. However, during these various molding processes, the inclusion of EvOH causes the following problems, and it is often difficult to use it as a food packaging material.

First of all, when molding a multilayer structure containing EVOH by coextrusion, EVOH and saturated polyester,
Even if the overall thickness distribution of the multilayer structure is made uniform, the thickness distribution of the E V O) i layer is not uniform, probably because the viscosity properties are vastly different from that of polyamide. During warranty elongation, gas barrier properties often deteriorated significantly due to crank and local uneven thickness.

Second, what is worse is that during coextrusion molding, if the EVOH layer is operated for a long period of time, minute streaks and bumps will occur in the EVOH layer, which not only spoils the appearance, but also cause cracks in the EVOH layer and slight unevenness in thickness during heating and stretching. increases, and the gas barrier properties deteriorate, making it unsuitable for use as a food packaging material.

Thirdly, even if the molding conditions and molding equipment ρ are improved to make the thickness distribution of the EVOH layer as uniform as possible, or even if EVOH sheets with uniform thickness are laminated by the dry lamination method, even when the sheets are heated and stretched, Often EVOH
There are cases where the gas barrier properties deteriorate significantly due to layer cranking, local thickness unevenness, etc., and the product becomes unusable.

Finally, the stretched multilayer structure (film, sheet, or container) is filled with food and heated to 70°C to 120°C.
EVOH is used for so-called shrink packaging, where the packaging material is heated to shrink the packaging material and packaged in close contact with the food.
Perhaps because the shrinkage stress or shrinkage rate is small, the adhesion to the food may be incomplete, the packaging bag may wrinkle, and pinholes are likely to occur in those areas, making it difficult to function as a gas barrier packaging bag. In some cases, the number of cases did not exceed 90%.

Therefore, in order to make the thickness distribution uniform during coextrusion molding, conventional methods have been used to select brands of saturated polyester, polyamide, and adhesive resin whose melt viscosity (melt index/MI) is close to EVOH, and to modify the coextrusion equipment. However, since EVOH and other resins essentially have different viscosity dependence on shear rate, even if the viscosity (melt index) under a constant shear rate condition is the same, It is not possible to greatly improve the thickness distribution, and since the viscosity of the saturated polyester, polyamide and adhesive resin is regulated, the problem often arises that the desired food packaging material cannot be obtained. On the other hand, due to modification of coextrusion equipment, sometimes E
In some cases, a uniform VOH layer can be obtained, but the operating conditions are very narrow.

The thickness distribution changes due to slight fluctuations in discharge speed and discharge temperature, making it difficult to maintain stable production.Also, when changing the brand of resin, extensive modification of the equipment itself must be carried out through trial and error. Not only does it take a lot of effort, time, and raw materials to establish the conditions, but because the accuracy of design calculations is currently at a very low level, it takes a lot of effort, time, and raw materials when remodeling or adding new equipment. This is a big problem as it is necessary to establish conditions by introducing Therefore, efforts have been made to improve the thickness distribution by adding additives to EVOH (
% opened in 1982, 20345), but the effect is not sufficient, and during long-term operation, bumps, streaks, and uneven flow are likely to occur, making it unusable.

On the other hand, EV
Blends of polyamide resins, aromatic sulfonamide plasticizers (JP-A-59-20345), and mixtures of glycerin, various glycols, hydroxyl group-containing plasticizers represented by polyhydric compounds, etc. 1988, 88067), etc., but it has been found that none of them is fully satisfactory in the following respects. That is, when polyamide resin is boria-blended with EVOH to obtain a multilayer structure, the polyamide resin and EVO () react and a large number of gelp-like substances (
Fish eyes) occur and the coloring becomes severe, making it unusable. When a multilayer structure is made into a container by secondary molding, the content of polyamide resin added to prevent the occurrence of cracks, pinholes, etc. in the EVOH layer is EV
It is necessary to add a large amount of 10 to 30 parts by weight per 100 parts by weight of OH. 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
10 parts as well as polyamide resin for 100 parts of VOH
Up to 20 parts by weight is necessary, but the gas barrier properties are greatly reduced. What's worse is that the plasticizer bleeds, probably due to insufficient compatibility with EVOI (EVOI) in multilayer containers.
The adhesive strength between the VOH layer and other resin layers decreases significantly over time, impairing the shape of the container. In other words, the above additives are unacceptable to use.

Regarding shrinkability (shrinkability), currently the shrinkage stress and elongation are increased on the polyamide or polyester side.
Measures are being taken to reduce the share of EVOH and B-. That is, there are methods of increasing the viscosity of polyamide or polyester resin, use of crosslinked modified products, or methods of locally crosslinking during coextrusion molding or after molding and then stretching.

However, these methods impair the thickness distribution of the EVOH layer during coextrusion molding, and it is difficult to recover defective products that occur during film formation or stretching, so there is currently no significant expansion into this field. It has become an obstacle.

Therefore, there is almost no deterioration in gas barrier properties, and the thickness of the EVOH layer during coextrusion molding is uniform, so it does not gel or become sticky during long-term operation. If EVOH with no uneven flow not only does not cause pinholes, cracks, or minute thickness deviations when heating and stretching the multilayer structure, but also has the property of increasing heat shrinkability, it will improve operability and cost. It is expected to make a significant contribution to the field of gas barrier food packaging.

Problems to be Solved by the C0 Invention The present invention is free from the above-mentioned drawbacks, has no unevenness between products and within a molded product, and therefore has no variation in the above-mentioned characteristics.
Modified silicon-containing E VO with extremely high homogeneity
The purpose is to use H to obtain a coextruded multilayer structure.

Means for Solving Problem D9 The present invention provides a melt molding material made of EVOH obtained by saponifying a copolymer of vinyl acetate, ethylene, and an olefinically unsaturated monomer containing silicon in a specific molecule; That is, vinyl acetate, ethylene and the following general formula (1),
Saponification degree of vinyl acetate component obtained by saponifying one or more copolymers selected from silicon-containing olefinically unsaturated monomers represented by (n) and (In) At least one side of the layer of silicon-containing EVOI having an ethylene content of 25 to 60 mol%, preferably 25 to 55 mol%, and a molar content of 0.0005 to 0.2 mol. Various laminated multilayer structures having a saturated polyester or polyamide layer on one or both sides of an EVOH layer via an adhesive resin are created by coextrusion method. If you do.

Even if the brand and viscosity of the adhesive resin and saturated polyester or polyamide are changed, and even if the structure and flow rate of the resin flow path of the coextrusion device are changed, the direction perpendicular to the discharge direction of the resin discharged from the coextrusion die is maintained. It was very difficult to make the thickness distribution of the EVOH layer uniform in the direction. As a result, E
There are many problems such as cracks during heating and stretching due to uneven thickness distribution of the VOH layer, deterioration of gas barrier properties due to local thickness unevenness, and the need to make the EVOH layer thicker than necessary to obtain a gas barrier-poor appearance. It was thought that the root cause of the above problem was that the viscosity-shear rate dependence of saturated polyester or polyamide and adhesive resin was different from that of EVOH resin, so various additives (plasticizer, crosslinking agent, Modifications were carried out by changing the copolymer composition and by changing the copolymer composition. As a result, although polyhydric alcohol plasticizers, carboxylic acid amide plasticizers, aromatic sulfonic acid plasticizers, etc. have the effect of reducing viscosity,
The effect of improving the thickness distribution of the VOH layer is so small that it is not practical. Although the method of changing the shear rate dependence of viscosity by cross-linking EVOH by adding peroxide is somewhat effective, it is visually unusable due to the occurrence of popping and uneven flow during long-term operation. Ta. Surprisingly, however, silicon-containing EVOH compositions have lower E
It was found that not only the thickness distribution of the VOH layer was uniform, but also very good, with almost no flow irregularities occurring during long-term operation. Even more surprisingly, when a multilayer structure having a saturated polyester or polyamide layer in the EVOH layer is heated and stretched, the EVOH
Compared to EVOH compositions containing single substances and other plasticizers, not only can very good molded products with almost no pinholes, cracks, or minute thickness deviations in the EVOH layer be obtained, but
It was found that the molded product had excellent gas barrier properties, especially under high humidity conditions, leading to the present invention.

Furthermore, it was completely unexpected that the heat shrinkability of the heat-stretched multilayer structure was found to be significantly improved. This fact is also clear from the examples described in detail below.

Sada is not the reason why the silicon-containing EVOH composition has the above-mentioned unexpected moldability improvement effect, but low polymerization degree EVOH containing a silicon compound partially Because it is reversibly crosslinked, it acts as a low molecular weight resin in the high shear rate range and as a high molecular weight resin in the low shear rate range, which may be due to the fact that the viscosity-shear rate with saturated polyester, polyamide, or adhesive resin decreases. EVOH during coextrusion molding with consistent dependence and actinic stress characteristics.
This is thought to be due to the fact that the thickness distribution of the layer can be easily made uniform. In addition, gelation of EVOH, which is the cause of spots, streaks, and uneven flow that occur during long-term operation, is also thought to be a characteristic of low polymerization degree EVOI. In other words,
Although the apparent viscosity shows a certain value due to partial and reversible crosslinking of silicon compounds, it is essentially an aggregate of low polymerization degree EVOH, and it is generally said that low polymerization degree resins are difficult to gel. The observed facts support the above inference (specificity of silicon compounds). Furthermore, as mentioned above, the moldability improvement effect in heating stretching processing is due to the partial plastic crosslinking effect of the silicon compound, that is, during high-speed deformation (stretching), Lr apparently interacts with the low molecular weight resin.

This is thought to be due to the fact that while deformation is facilitated, the strength of the high molecular weight component due to crosslinking is taken into account, so the stretchability increases by 1/C in width.

On the other hand, regarding the shrinkability during heating, the silicon compound has a partial, plastic crosslinking effect, which acts as a high molecular weight crosslinked resin during low-speed deformation (shrinkage), and as well as a rubber-like elastic recovery effect, shrinkage stress and shrinkage It is thought that this may have led to an increase in the rate.

F0 More detailed description of the invention In the present invention, the melt molding material made of the EVOH contains 25 to 60 mol % of one type of ethylene, preferably 25 to 55 mol %.
It is preferable that the degree of saponification of the vinyl acetate component of the copolymer is 95 moles or more, and if the ethylene content is 25 moles or less, it will maintain good melt molding processability while maintaining moisture barrier properties against oxygen, etc. It is difficult to greatly improve the effect of improving dependence, etc., and on the other hand, 55 mol%
, especially over 60 momoles. This reduces the barrier properties against oxygen, etc., and the fragrance retention properties, which are the characteristics of EVOH. ′! When the saponification degree is less than 95 mole, the barrier property is poor.

The oil resistance will decrease and EVOH will not be able to maintain its original properties, or it will be difficult to enjoy the effects of the present invention. 1), (II) and (III)
It is preferable to use one kind of fc selected from among the compounds represented by the above, but two or more kinds of fc can be suitably used.

[However, here, n is 0 to 1. m is 0-21R" is a lower alkyl group, allyl group is a lower alkyl group having an allyl group, R2 is a saturated branched or unbranched alkoxyl group having 1 to 40 carbon atoms, and the acyloxyl group is an oxygen II3 is hydrogen or a methyl group R4 is hydrogen or a lower alkyl group R5 is an alkylene group or a divalent organic residue in which chain carbon atoms are bonded to each other by oxygen or nitrogen , R' is hydrogen, halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group; You can leave it there.

), R is hydrogen, halogen, a lower alkyl group, an allyl group, fc is a lower alkyl group having an allyl group, and R9 is a lower alkyl group. ] More specifically, R1 is a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a C 1 having an allyl group having 6 to 18 carbon atoms.
~5 represents a lower alkyl group R4 represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms 1R5Vi represents a lower alkyl group having 1 to 5 carbon atoms
Indicates a divalent organic residue in which ~5 alkylene groups or chain carbon atoms are interconnected by oxygen or nitrogen.
R6 is hydrogen, halogen, a lower alkyl group having 1 to 5 carbon atoms, or an allyl group having 6 to 18 carbon atoms.

fcFi 1 carbon number having an allyl group having 6 to 18 carbon atoms
-5 lower alkyl group, f17n carbon number 1-40
represents an alkoxyl or acyloxyl group (here, the acyloxyl group or acyloxyl group may have a substituent containing oxygen or nitrogen), R8 is hydrogen,
Halogen, lower alkyl group having 1 to 5 carbon atoms, 6 to 5 carbon atoms
18 represents an allyl group or a lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms, and 19 represents a lower alkyl group having 1 to 5 carbon atoms.

Examples of the silicon-containing olefinically unsaturated monomer represented by the general formula (1) include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyljethoxysilane, and vinyldimethylethoxysilane. , allyltrimethoxysilane.

Allylmethyldimethoxy7rane, allyldimethylmethoxysilane, allyltriethoxysilane, allyldimethylethoxysilane, vinyltris(β-methoxyethoxy)silane, vinylisobutyldimethoxysilane, vinylethyldimethoxysilane, vinylmethoxycyphtoxysilane, vinyldimethoxybutoxysilane 1 Vinyltriphtoxysilane, vinylmethoxydihexyloxysilane, vinyldimethoxyhexyloxysilane, vinyltrihexyloxysilane, vinylditoxyoctyloxysilane, vinyldimethoxyoctyloxysilane, vinyltrioctyloxysilane, vinylmethoxysilauri Roxysilane, vinyldimethoxybutoxysilane, vinylmethoxydioleyloxysilane, vinyldimethoxybutoxysilane.

Examples include polyethylene glycol derivatives of vinylmethoxysilane represented by the general formula % (where m is the same as above and X represents 1 to 20), but vinyltrimethoxysilane is preferred from an economical standpoint.

As the silicon-containing olefinically unsaturated monomer represented by the general formula (n), 3-(meth)acrylamidofurobyltrimethoxysilane CHz=CRCNH(CH2)3S i (OCHs
)33-(meth)acrylamidofurobyltriethoxy7ran CH2=CRCNH(CH2)3S i (0CH2
CHs) a3-(meth)acrylamido-propyltri(β-methoxyethoxy)silane CH2=CRCNH(CH2)3 Si (OCH2
CH20CH3)! 3-(meth)acrylamido-propyltri(N-methylaminoethoxy)silane CH2=CRCNH(CH2)3S i (OCH2
CH2NHCH3)3♂ 2-(methacrylamide-ethyltrimethoxysilane 0M2=CRCNH(CH2)2Si(QC)ia)3
1-(meth)acrylamido-methyltrimethoxysilane CH2=CRCNHCH2Si(OCH3) 32-(meth)acrylamido-2-methylfuropyltrimethoxysilane CH3 2-(meth)acrylamido-isopropyltrimethoxysilane CH22CRCNHCH2Si(OCH3) L2Si (OCH3)3
(meth)acrylamide-linear or branched alkyltrialkoxysilane N-(2-(meth)acrylamido-ethyl)-aminopropyltrimethoxysilane such as CHa (R represents hydrogen or methyl group) CHz=CRCONHCH2CH2NH(CHs+) 3
S i ((JCHa)3(3-(meth)acrylamido-propyl)-oxypropyltrimethoxysilane CH2=CRCONH(CH2)30(CH2)3S
i (OCRs)3 (R represents hydrogen or methyl group)
(meth)acrylamide-nitrogen-containing or oxygen-containing alkyltrialkoxysilane 3-(meth)acrylamidopropyltriacetoxysilane CHz=CRCONH(GHz)3Si(OCOCHa
)s2-(meth)acrylamide-ethyltriacetoxysilaneCHz=CRCON)i(GHz)2Si(OC
OCH3)34-(meth)acrylamide-butyltriacetoxysilaneCHz=CRCONH(CHz)4Si(OCOCHa
) 33-(meth)acrylamidoprobyltrigropionyloxysilane CH2=CRCONH(CH2)a Si (0CO
CH2CH3)32-(meth)acrylamido-2-methylglobiltriacetoxysilane CL(a CH2=CReONIieCH2Si(OCOCHa)
3CHa N-(2-(meth)acrylamide-ether)aminopropyltriacetoxinranCHz = CRCONHCHzCH2NH(CH2)3
(Meth)acrylamide-alkyltriacyloxysilane, 3-(meth)acrylamide-propylinbutyldimethoxysilane CH2CRCONH(CHz)3Si(OCHs) such as S i (OCOCHs)3 (R represents hydrogen or a methyl group) 2
CH3CHCH2CH3 2-(meth)acrylamide-ethyldimethylmethoxysilane CH3 CH2=CRCONH(CHz)2SiQC)H3籭CH3 3-(meth)acrylamide-ethyldimethylmethoxysilane GHz =CRCQNH(CH2)3S i (OCO
CHs)2(GHz)7C)ia 1-(meth)acrylamide-methylphenyldiacetoxysilane CHz=CRCONHCzS 1(OCOC)is)
2C6out3-(meth)acrylamidofuropylbenzyldiethoxysilane C)iz=CRCONH(GHz)3Si(OCHz
CHs) 2-deprived CH2-C8H5 2-(meth)acrylamido-2-methylfurobyl monochlorodimethoxysilane CH2=CRCONHC(CHa)2CH2S 1(O
CRs ) 2 day α 2-(meth)acrylamido-2-metelfurovirhydrodienemethoxysilane H3 CHz=CRCONHCCH2S i (OCH3)2
(meth)acrylamidoalkyl di- or monoalkoxy or di- or monoacyloxysilane such as CH3H (R represents hydrogen or a methyl group);

3-(N-methyl(meth)acrylamide)-propyltrimethoxysilane CHz=CRCON(CHz)3Si(OCHs)3SH3 2-(N-ethyl-(meth)acrylamide)-X tyltriacetoxysilane CHz=CRCONEHzCH2S i(0COCH3
)3H2CH3 (R represents hydrogen or methyl group)
Examples include (meth)acrylamido)alkyl trialkoki/or triacetoxysilane. 3 of these
- (Meth)acrylamide-propyltrimethoxysilane and 3-(meth)acrylamide-propyltriacetoxysilane are relatively easy and inexpensive to produce industrially, and 2-(meth)acrylamide-2-methylpropyltrimethoxysilane Silane and 2-(meth)acrylamido-2-methylphenyldiacetoxysilane are preferably used because the amide bond is extremely stable against acids or alkalis. Here, modified silicon-containing EVO obtained by copolymerizing a silicon-containing monomer represented by general formula (n) with vinyl acetate and ethylene and saponifying the resulting copolymer) i contains a copolymer unit represented by the following general formula (If/).

(Here, R3, R', R5, R', mVi are the same as above; RIO represents a hydroxyl group, and a salt of a hydroxyl group represented by the general formula 〇M (M represents an alkali metal or NH4).) General formula (Ill ) as the silicon-containing olefinically unsaturated monomer.

Vinyltriacetoxysilane CH2=CH81 (OCCHs)3 Vinyl trifluoropionyloxine CH2=CH8i (OCCkhCHs)3 Impropenyltriacetoxysilane CHa CHz=C8i (OCCH3)3 Vinylisobutyldiacetoxysilane CH2=CH81 (OCOCHa).

CH3CHCH3 Vinylmethyldiacetoxysilane CH2=CH81(OCOCHs)2 Ha Vinyldimethylacetoxysilane Hs ■ Vinylphenyldiacetoxysilane Vinylmonochlorodiacetoxysilane α O Examples include vinylmonohydrodienediacetoxysilane, but economically speaking, vinyl Triacetoxysilane is preferred.

The copolymerization of the silicon-containing olefinically unsaturated monomer described above with vinyl acetate and ethylene is preferably carried out by solution polymerization in the presence of alcohol. As for the alcohol, lower alcohols such as methanol and ethanol are usually preferred industrially. Copolymerization can be carried out either batchwise or continuously. The ethylene content of EVO)i mainly depends on the vinyl acetate present in the copolymerization system and the amount of ethylene dissolved in the system, and the latter mainly depends on the polymerization ethylene pressure and temperature. In some cases, the silicon content of the modified EVOH is primarily governed by the quantitative relationship between vinyl acetate and silicon-containing olefinically unsaturated monomers present in the system. It is well known that in the case of a batch process, the copolymer composition varies with the polymerization rate according to the copolymerization reactivity ratio, but it seems that the monomer composition remains constant - one or both monomers. In order to obtain a copolymer with a uniform copolymerization composition, it is necessary to adopt the so-called semi-batch method of adding
stry) Vol, 49.42.208-209(1
957). In the case of a continuous system, a completely mixed one-stage flow system reaction system in which the stirring mixing tank has a copolymer composition is most suitable, and in the case of a multi-stage flow system reaction system of two or more stages, the same method as above is used. For this reason, it is more preferable to add monomer to the nuclide in the second and subsequent stages so that the monomer composition in each stage of the copolymerization tank is constant. As a polymerization initiator, 2゜2'-azobis(4-methoxy-
Nitriles such as 2,4-dimethylvaleronitrile), 2,4,4-trimethylvaleronitrile, 2,2'-azobisisobutyronitrile, di-n-probilveroxycarbonate, vinyl x- Carbonates a, such as 4-t-butylcyclohexyl peroxydicarbonate, bis-2-ethylhexylsilyl dicarbonate,
Known radical initiators such as peroxides such as acetylcyclohexane sulfonyl peroxide, benzoyl peroxide, and lauroyl peroxide can be used. In particular, a polymerization initiator with a shorter half-life is suitable for long-term continuous polymerization operations because it can almost completely or largely suppress the formation of gel-like substances that are insoluble in the polymerization system over time during copolymerization. used.

The hexacopolymer obtained by polymerization is first subjected to a saponification reaction. The saponification reaction is advantageously carried out in a known manner, for example using an alkaline catalyst, that is, usually in the form of an alcoholic solution of the copolymer, and the reaction is carried out by alcoholysis. On duty.

A method disclosed in Japanese Patent No. 572,889 and Japanese Patent No. 61, No. 557, in which methyl acetate, which is produced as a by-product during the saponification reaction, is removed from the top of the tower by blowing alcohol vapor into the bottom of the tower, using a basic reactor. can be used most suitably.

As the alkaline catalyst used in the saponification reaction, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alcoholades such as sodium methylate and potassium methylate, and the like are used. In particular, IJium (hydroxide) is industrially and economically advantageous. Saponification temperature is 6
The temperature is suitably selected from the range of 0 to 175°C. In particular, when using the base type reactor, a temperature of 100°C or higher is preferable from the viewpoint of shortening the reaction time, solubility of the silicon-containing EVOH in alcohols, etc., although this is also related to the composition of the copolymer. .

In the saponification reaction, vinyl alkoxysilane units are also partially or highly saponified to form vinyl silanol units,
It is converted into its alkali salt or its intercondensate.

However, in the copolymer containing the monomer represented by the general formula (■) above, the amide bond of the silicon-containing polymerizable monomer unit did not decompose in the saponification reaction using an alkaline catalyst and remained stable. It will be done. However, during the saponification reaction, the silicon-bonded alkoxyl group, carboxyl group, hydrogen, and halogen of the silicon-containing monomer unit represented by the general formula (■) are simultaneously partially or highly saponified and converted into hydroxyl groups or alkali salts of hydroxyl groups. be done. Furthermore, some of these hydroxyl groups are present in the modified EVO1 obtained after the saponification reaction.
(When drying the molding material, these reactive groups may be bonded together to form siloxane bonds depending on the drying conditions. The modified EVOH molding material in which many siloxane bonds are formed may have poor thermal meltability. In such cases, the content of the silicon-containing monomer should be adjusted, or (meth)acrylic-amide-branched alkyl, which has extremely high stability against alkali, should be used as the silicon-containing polymerizable monomer unit. Modified EVOf having a silane unit (preferably used as a molding material) After the saponification reaction, known methods can be applied to isolate the modified BVOII molding material, including Japanese Patent No. 725,520. The method of precipitating the polymer in the form of strands and separating the polymer as disclosed in No. During the saponification reaction during the acid treatment, the alkoxyl group, carboxyl group, hydrogen, and halogen bonded to silicon are converted into an alkali salt of hydroxyl group, resulting in a hydroxyl group.

The modified silicon-containing EVOH molding material according to the present invention is extremely satisfactory from the viewpoint of improving the inherent properties of EVOH resin and imparting properties compatible with other resins and processing methods. The content of the combined silicon-containing monomer is varied depending on the purpose to produce the modified EV suitable for each case.
When obtaining an OH melt molding material and combining it with other resins having a low melt viscosity index, it is often encountered that there is a large difference in melt viscosity and a phenomenon indicating melt viscosity inconsistency is observed. , the modified EVO in which the melt viscosity index of the EVOH resin is lowered by the modification of the present invention while maintaining the composition (the modified EVO resin of the present invention can be used to eliminate the melt viscosity mismatch by using a resin molding material) The usefulness of the material is extremely dependent on the uniformity of its modification.If the content of the silicon-containing monomer is too small, the modification effect will not be exhibited, and if it is too high by 1'fc, crosslinking will occur. The content is selected depending on the purpose, but is 0.0005 to 0.2.
mole es.

In particular, a range of 0.001 to 0.1 mole is preferable.0 Here, the silicon content refers to the amount of silicon-containing monomer in the silicon-containing monomer-vinyl acetate-ethylene copolymer (mol%
).

As mentioned above, the modified silicon-containing EVOHFi of the present invention can be used more satisfactorily for all conventional purposes, but it also has the desired properties derived from its silicon content, such as aluminum foil. , improved adhesion with other resins, etc. can be advantageously utilized.

Modified 7yEVO in the present invention) (ASTML)
-6 melt viscosity index measured by T-1238-T
Unte ° Pugu person (thin end - wide) is 0.
05P/10 minutes or more, further 0.05~10F/
10 minutes is preferable, especially 0.1~l Or/l
0 minutes is suitably used for various uses such as films, sheets, containers, etc., either unstretched or at least uniaxially stretched.

The silicon-containing EVOH of the present invention is an EVOH having a specific ethylene content and silicon content obtained by saponifying a copolymer of vinyl acetate, ethylene, and the specific silicon-containing olefinic unsaturated monomer. However, the copolymer may contain another third substance as a copolymer component within a range that does not affect its properties. Examples of the third substance include α-olefins having 3 or more carbon atoms, acrylic acid, meth-acrylic acid, and esters of these acids. In addition, this silicon-containing EV
It is free to mix ordinary EVOH into the OH to the extent that it does not impede the purpose of the present invention.As mentioned above, the silicon-containing EVOH of the present invention is used in combination with a saturated polyester resin or a polystyrene resin. However, in recent years, in combination with the diversification of properties and the increasing sophistication that are particularly required, two-layer FC, which is made by combining various other resins, has become suitable for use as a multilayer laminate structure with two or more layers. It will be done. A coextrusion method is used for compounding, but in this case, saturated polyester resin'! EV with a desired ethylene content that does not cause melt viscosity mismatch with polyamide resin or polyamide resin.
QH can be obtained by appropriately selecting the silicon content.

Examples of the layer structure of the multilayer structure include:

Saturated polyester (hereinafter referred to as PET) / adhesive layer (hereinafter referred to as AD) / silicon-free EVOH (hereinafter referred to as St-E
PET/AD/5i-EVO
H/AD/PET, PET/AD/5i-EVOH/A
D/P.E.

PET/AD/5t-EVOH/AD/ionomer,
PET/AD/5i-EVOH/AD/PP, polyamide (hereinafter referred to as PA)/5i-EVOH/PA,
PA/AD/5i-EVOH/AD/PE, PA/A
D-8i-EVOH/AD/7 Io/? -, P
ET/AD/St-EVOH/AD/PA
Examples include, but are not particularly limited to.

In the present invention, the polyamide resin is produced by a polycondensation reaction of W-aminocarboxylic acid or a polycondensation reaction of a tribasic acid and a diamine.
O-nylon, type 1-nylon, 12-nylon, copolymers thereof, and the like are preferred, and particularly preferred is a copolymer polyamide resin of ε-cagflectam and hexamethylene diammonium adipate.

Saturated polyester resins are obtained by the condensation of saturated dibasic acids and glycols, such as polyethylene terephthalate, phthalic acid, isophthalic acid, sebacic acid, adipic acid, and azelaic acid obtained from ethylene glycol and terephthalic acid. , a polyethylene terephthalate copolymer containing a saturated dibasic acid such as glutaric acid, succinic acid, and oxalic acid as a copolymer component, and 1. as a diol component. -4-Cyclohexane dimetatool, diethylene glycol, propylene glycol, etc. are polyethylene terephthalate copolymers or polybutylene, or blends thereof.

The adhesive resin used for the adhesive layer varies depending on the type of resin laminated adjacent to the 5i-EVOH, but for example, maleic anhydride graft-modified PE, maleic anhydride graft-modified PP, maleic anhydride graft-modified ethylene-
Ethyl acrylate.

+1 selected from ethylene-vinyl acetate copolymer, maleic anhydride graft modified ethylene-vinyl acetate copolymer, etc.
species or a mixture of two or more species, or with these, 5i-E
VOH blends and the like can be selected from among these.

When commercializing the laminated structure into containers, etc., it is economically important to reuse scraps and rejected products of the laminate generated during molding. alone or blended with resin and/or adhesive.
It can be used by laminating it with t-EVOH or other thermoplastic resin.

In the present invention, a method for obtaining a multilayer structure is 5t-E
A method of coextruding VOH and a saturated polyester or polyamide resin via an adhesive resin (the feed block method is a multi-manifold method), a method of coextrusion lamination, a method of creating a coextrusion pipe, or a coextrusion method. A method of creating a parison by injection molding, or a method of forming a laminate obtained in this way by vacuum pressure deep drawing, biaxial stretching molding,
In order to use the stretched multilayer structure/body for heat shrinking purposes, it is necessary to use the stretched multilayer structure/body as much as possible after stretching is completed. It is preferable to perform the quenching operation at an early stage, and methods include quenching with a mold, metal roll, etc., quenching with water or air, etc., but there are no particular limitations as long as it is a commonly used method. do not have.

- If the stretched multilayer structure is used as is for food packaging purposes, it is often heat-set for the purpose of improving strength and dimensional stability.
The method generally used for polyester or polyamide can be applied, and is not limited to %. for example.

In the case of a polyester-containing multilayer film, 3x3 times sequential biaxial stretching followed by heat treatment using a roll or tenter for 19
One method is to carry out heat fixation at 0 to 230°C.

Furthermore, there are no particular limitations regarding the thickness structure of the multilayer structure, but when considering molding 1'L, cost, etc., the thickness ratio of the EVO) i layer to the thickness of all layers is 2 to 2.
Approximately 0% is preferable.0 In addition, in the present invention, there is no particular restriction on the water content of the EVO) 1 composition layer, which is a component of the multilayer structure, in the heat stretching process, but it is from 0.01 to 0.01.
It is preferable that it is within 10%.

The thus obtained multilayer structure of the present invention and its heat-stretched product have a uniform thickness of the EVOH composition layer.9. There are no streaks or cracks, and there are no pinholes, cracks, or uneven thickness that tend to occur during stretching, so it has extremely good gas barrier properties, and can be used as food packaging materials, containers, and containers that require smooth gas barrier properties. Useful.

The present invention will be further explained below with reference to examples, but the present invention is not limited in any way by these examples. In the examples, 1 (l or %) indicates parts by weight or % by weight unless otherwise specified.

<Thickness distribution measurement of coextruded product> PET/AD/EVOH/A discharged from a die width of 550 cm in a feed block type 3 type 5 layer coextrusion device
D/PET MatatiPA/AD/EVOH/AD/PA
Measurements were performed on sheets (PP, AD, pso brands, see below) formed into films at a take-up speed of IVmin.

The thickness of the EVOH Asahi in the center of the above sheet is Aμ.

If fc is the average thickness of the left and right Loans from the center, Bμ.

EVOH/mO thickness 1ll (X%) as X=(B-A)
/AX100(%) is defined.

FA nylon (Mitsubishi Kasei Tsubamido Roao)
450μE V OH center thickness 50μ Target (method for measuring moisture in EVOH layer) Peel off the EVOH layer in the multilayer structure just before heating and stretching, leave it in a hot air dryer at 120°C for 24 hours, and reduce the EVAL layer due to weight loss. Calculate the moisture content of the sample.This value will be expressed as burnt and referred to as volatile content.

Example 1 Continuous polymerization was carried out under the conditions shown below to obtain a silicon-containing ethylene-vinyl acetate copolymer in a polymerization tank with a volume of tio, g and equipped with a stirrer and a cooling coil inside.

Vinyl acetate supply 1 4809/hr Methanol supply lit 409/hr Vinyl-trimethoxysilane supply amount 355
4/hr2.2'-Azobisisobutyronitrile
331F/hr polymerization temperature
77℃ polymerization tank ethylene pressure
60 to 1Δ, (G average residence time
The polymerization rate of vinyl acetate for 5 hr+s was about 50%. The copolymerization reaction liquid was supplied to a purging tower, and unreacted vinyl acetate was removed from the top of the tower by introducing methanol vapor from the bottom of the tower, to obtain a methanol solution of 45 grams of the copolymer. According to nuclear magnetic resonance analysis, the copolymer contains 0.027 mol% of divinyltrimethoxysilane units and 5% of vinyl acetate units.
It was confirmed that it contained 9.5 mol%, about 40.5 mol of ethylene units. A methanol solution of the copolymer is introduced into a basic saponification reactor, and sodium hydroxide is added at a molar ratio of 0 to the vinyl acetate component contained in the copolymer.
．． 05 to the reactor, dimethatol vapor is blown into the bottom of the column, and a saponification reaction is carried out while removing by-product methyl acetate from the top of the column, and a methanol solution of the modified EVOH is obtained from the bottom of the column. Ta. Mixed steam with a weight ratio of methanol/water = 7/3 was blown into the methanol solution to change the solvent composition in the solution to a water/methanol mixed system, and then discharged in the form of a strand into a 5°C methanol 10es aqueous solution. The EVOH was isolated as pellets by coagulation, precipitation, and cutting. After sufficiently washing with water, the sample was immersed in dilute acetic acid water and dried at 65°C to 0°C. The zero saponification degree was 99.3 mol.

The EVOH, nylon (Mitsubishi Kasei Tsubamide 1 o a
o) and adhesive resin (manufactured by Toyo Soda Co., Ltd. [Mersene M54
20J (gra-7toethylene-vinyl acetate copolymer of maleic anhydride)) was fed into a feedblock type 3-type 5-layer coextrusion device at a die temperature of 250°C and a rate of 1@/min.
A PA/AD/Si sheet was obtained using a sheet take-up device.

The thickness of each layer is 450μ for the PA layer and 450μ for the contact IF layer (A D
) Each layer is 50tt, EVOH/ide is about 50μ. The thickness variation rate (thickness distribution in the direction perpendicular to the ejection direction) of the EVOH layer of this sheet was 5%, and almost no streaks, bulges, or flow irregularities were observed. The obtained sheet was deep drawn in a vacuum-pressure forming machine (FK-0431 manufactured by Asano Institute) at a sheet temperature of 120°C (the volatile content of the EVOH layer before forming was 0.7%). As a result, the transparency of the molded container was good, and no cracks or minute thickness deviations were observed (the deep drawing ratio of the molded container was 1.5).

This drawn and molded container was heated at 20℃-100%RH and at 20℃-100%RH.
After thoroughly controlling the humidity at 65% RH (about 1 month),
The amount of oxygen permeation was measured using a Mocon oxygen analyzer (manufactured by Mocon). As a result, the amount of oxygen permeation through the EVOH layer was 1.1 ee"20μ/n?・24hr-atm (20
℃-654RH), 10cc・20μ/n?・24 hours
-atrn (20° C.-100% RH) showed very good gas barrier properties.

Comparative Example 1 The same procedure as in Example 1 was carried out except that vinyltrimethoxysilane was not used to obtain 1 (VOH) with an ethylene content of 40.7 mol % and a saponification degree of 99.4 mol.

A melt-packed film was prepared in the same manner as in Example 1. As a result, the sheet E
The thickness variation rate of the VOH layer is 65%, which is very non-uniform, and the occurrence of wrinkles and spots is noticeable after 2 to 3 hours of film formation, making it difficult to use it during eating. Also,
5PPP (solid phase air pressure forming) molding was performed on the parts of this sheet with small thickness variations using a vacuum pressure forming machine, but a large number of glue sticks were observed to be visible to the naked eye on the sides of the molded product, making it unusable. . The oxygen permeation rate of this container is 4000cc-20μ/rI 24hr-atm (2
It was found that the EVOH layer was cut. The oxygen permeation rate of the original fabric before vacuum pressure forming is 1. OCC・20μ/rII・24hr-at
m (20℃-65%RH), 20cc・20p/r
1.24 hr-atm (20° C., 100 RH).

Comparative Example 2 In Comparative Example I, in order to investigate the cause of cracks that occurred on the side of the molded product during vacuum-pressure molding, the EVOH used in Comparative Example 1 was formed into a film using a 40φ monomer extruder, and half of the film with a uniform thickness was formed. An EVOH layer was obtained (50μ film, thickness variation rate 59b). A 1000 μ nylon sheet (Mitsubishi Kasei Tsubami 1030 monomer sheet) treated with an anchor coat (Toyo Moat yAT-335A) was dry laminated with EVOH film, and then deep drawing was performed using a vacuum-pressure forming machine. Similar to 1, slight cracks were observed on the side of the container. The volatile content of the EVOH layer at this time is 0; 8, *
Therefore, the abnormalities (cracks) during deep drawing that occurred in Comparative Example 1 were not due to uneven thickness, streaks, or spots of the EVOH layer during sheet creation, but were essentially caused by the It turned out to be a characteristic of EVOH.

Comparative Example 3 The EVOH used in Example 1 had a [η value (measured with 154 hydrated phenol at 30°C) of 0.084 (J/f), and M I□. (190°C load 216 (9 melt index value measured in l) is 2.1 (y/10 min), compared to [η
], = o, ost (x/r), M 1 type. . =
16.5 (P/le). M 1 type. EVOHl 00Mk used in comparison MJ1 because the difference in o may be considered to be the cause of abnormalities in film formability and deep drawing formability.
m to 1. -0.35 parts by weight of CBPO (benzoyl peroxide) was blended, and crosslinked pelletization was performed using a 40φ extruder at 220°C.

The obtained pellets were dried at 90°C for 16 hours to obtain M1 type. o was measured and found to be 1.8F/10 minutes. Although the H was lower than that of Comparative Example 1, it was not as high as that of Example 1. In addition, minute spots were observed on the Ev camphor layer of this sheet from the beginning of operation, and after 2 to 3 hours, streaks and
Flow unevenness increased, making it difficult to continue operation. Vacuum-pressure forming was performed in the same manner as in Example 1 on a part with relatively few bumps and streaks and a relatively good thickness distribution at the initial stage of operation, but many cracks occurred on the sides of the molded product, making it unusable. I couldn't stand it.

Example 2 Using the same polymerization tank as in Example 1, continuous polymerization was carried out under the conditions shown below.

Vinyl acetate supply amount 440 r/hrt
-Butanol supply amount 60 〃2.
2-Azobis-(2,4-dimethylvaleronitrile)
Type 101Ni/hr3-acrylamide-propyltrimethoxysilane 150 q/hrPolymerization temperature
60℃ average residence time
13 hrs polymerization tank ethylene pressure
The polymerization rate of 46 Ky/adG vinyl acetate was about 55 Ky. The copolymer was determined by nuclear magnetic resonance analysis,
0.013 mol% of 3-acrylamide-propyltrimethoxysilane units, 65 moles of vinyl acetate units,
It was confirmed that it contained about 35 moles of ethylene units.

The product was saponified and isolated in the same manner as in Example 1, post-treated, and dried to obtain modified EVOH. Saponification degree is 99.2
Morti, Mll. is 0.7. P/ It was 10 minutes.

Same as Example 1, P A/A D/5 in coextrusion equipment.
A sheet of t-EVOH/AD/PA composition 07 with a thickness of about 1° was obtained. The thickness variation rate of this sheet was 5 inches, and even after long-term operation (2 to 3 days or more), there were very few streaks, drops, and uneven flow. The obtained sheet was subjected to a biaxial stretching test device (Pandagraph type, Toyo Seiki!!), and the sheet temperature was 120°C, and simultaneous biaxial stretching was performed by a factor of 3 x 3. The volatile content of the gvoH layer before stretching was 1 As a result, it was found that a co-stretched film with no cracks in the EVOH layer, a uniform thickness distribution, and good transparency could be obtained.

After heat-setting this film at 170°C for 10 minutes, the oxygen permeation amount is Q, 5cc・20μ/m”・24h
r-atm (20°C-65%RH), 18 cc-2
0tt/n? -24hr -atm (20℃-100%
RH) showed very good gas barrier properties.

Comparative Example 4 The same procedure as Example 2 was carried out except that 3-acrylamide-propylmethoxysilane was not used, and ethylene content was 35 mol%, saponification degree was 99.3 mol%, MI was 4. o
An EVOH of 2.1 r/10 min was obtained. Coextrusion film formation was carried out in the same manner as in Example 2, and the EVOH layer of the obtained sheet had a very poor thickness variation rate of 68%, and was not only nonuniform, but also had streaks and streaks after 3 to 4 hours of continuous operation. Wow, the uneven flow has become noticeable. Biaxial stretching was carried out in the same manner as in Example 2 at the initial stage of operation and at a portion where the thickness variation and unevenness of the EVOf layer were relatively small. At this time, the volatile content of the EVOf layer was 0.28 inches. This biaxially stretched film had a network of cracks all over its surface, making it completely unusable.The amount of oxygen permeation of this biaxially stretched film was 4.
000cc-20μ/rr? -24hr-atm (20
℃-1004Rf() or higher, which indicates that the EVOf layer has been cut.The oxygen permeation rate of the original fabric before vacuum pressure forming is 0.6cC-20μ/n?
℃-654RH), 31cc-20μ/n? -24hr
-atm (2Q°C-100%RH).

Comparative Example 5 15 parts by weight of N-ethyltoluenesulfonamide was added as a plasticizer to 100 parts by weight of gVOH used in Comparative Example 4, and pelletization was performed using a 40φ extruder at a die temperature of 220°C. . This pellet was heated to 95°C-1
After drying for 6 hours, coextrusion film formation was performed in the same manner as in Example 2. The thickness variation rate of the obtained sheet was 21 inches, which shows a slight tendency to improve, but it was not sufficient and to make matters worse, 20 to 30 minutes after the start of operation, streaks and uneven flow occurred frequently on the sheet, making long-term operation difficult. there were. A portion at the beginning of operation and where the thickness distribution was relatively good was sampled and co-stretched in the same manner as in Example 2. As a result, although there was some unevenness in the stretching, it appeared that a relatively good stretched film with no cracks was obtained, but at first glance, the oxygen permeability was measured at 5cc/20μ/Tr.・24 hours
-atm (20℃-654RH), 98cc-20μ/
n? -24hr-atm, which was a large amount of oxygen permeation, was found to be unsatisfactory as a food packaging material with gas barrier properties. Since the crystallinity of pEVOH decreases due to the addition of a plasticizer, the moldability tends to improve, but it is thought that this is because the gas barrier properties, which are strongly related to the degree of crystallinity, worsened due to the decrease in crystallinity.

Example 3 In Example 2, the thickness structure of the coextruded raw sheet was
Each layer 300μ, AD% each 100p, EVOH/i5$2
PA created in the same manner as in Example 2 except that it was changed to 00μ
/AD/FJvOH/AD/PA coextruded raw sheet was subjected to a Pandagraph type biaxial stretching device (manufactured by Toyo Seiki Co., Ltd.), and simultaneous biaxial stretching was performed 3x3 times at sheet temperature 1 type 0°C. . Immediately after the stretching was completed, a cold air type quenching device (cold air temperature -10° C. to 0° C.) attached to the apparatus was activated to perform rapid cooling with cold air blown from the air nozzle.

The thermal shrinkage rate and stress of the resulting rapidly cooled and co-stretched multilayer film were measured and the results are shown in Table 1. In comparison with Comparative Example 6, which will be described later, it can be seen that the heat shrinkability is greatly improved. In addition, when the film was made into a bag using Heat Me 2- and a ham with a diameter of approximately 10α and a height of 2 crx was placed in a shrink wrapping machine, a good product with no creases or wrinkles was obtained.
See Thorn 1) 0 Comparative Example 6 PA/AD/EVOf(/A
A quenched co-stretched multilayer film was obtained by carrying out the same operation as in Example 3 using a D/PA coextruded raw sheet. The heat shrinkage rate and filtering force of this film are shown in Hikari 1, and the heat shrinkage is poor compared to the silicon compound-containing EVOH (Example 3) film. Furthermore, when an actual packaging test using ham was carried out in the same way as in Example 3, the packaging was not completely sealed, and the film had creases, twists, etc., and was not suitable for practical use.

Table 1 Example 4 In Example 2, 3-acrylamide-allopyltriacetoxysilane was used as the silicon-containing monomer at 290~/h.
The operation was performed in the same manner as in Example 2, except that r was used. It was confirmed by nuclear magnetic resonance analysis that the polymer contained 0.02 mole of 3-acrylamidopropyltriacetoxysilane units, and that the composition of vinyl acetate and ethylene was almost the same as in Example 2. The degree of saponification of the modified EVOH is 995 mol, Mll, o is 0.3 f
/ For 10 minutes, add the EVOH, saturated polyester (Japan Unibet Company Friends, "Unipet RT533J
) and adhesive resin (Mersene M5420 manufactured by Toyo Soda Co., Ltd.
) was fed to a multi-manifold type 3m5-layer coextrusion device, and a sheet with a total thickness of approximately 1m of PET/AD/EVOH/AD/PET composition was obtained using a die temperature of 210°C and a sheet take-up device of 1m/min. The thickness of each layer was 450μ for each PET layer, 50μ for each adhesive layer, and about 50μ for the EVOH layer.

The thickness variation rate (thickness distribution in the direction perpendicular to the discharge direction) of the EVOH layer of this sheet was 3-chip, and almost no streaks, drops, or flow irregularities were observed in the EVOH layer even after long-term operation of 20 to 24 hours. . The obtained sheet was passed through a vacuum pressure forming machine (using a square mold with a drawing ratio of 1.5 manufactured by Asano Research Institute).
When drawing was performed at 95°C, a good molded product with no cracks was obtained.The oxygen permeation rate of this container was 0.4 c.
c -20p/rrl ・24 hr-atm (20℃
-654RH), 19cc-20μ/+/-24hr・
ATM (20°C-654RH) and showed very good gas barrier properties.

Comparative Example 7 The same procedure as Example 3 was carried out except that 3-acrylamide-propyltriacetoxysilane was not used. Ethylene content was 34.5 mol%, saponification degree was 99.5 mol%, M
1st type 9o obtained EVOH of 1.9f/10min. Coextrusion film formation was performed in the same manner as in Example 4.

The resulting sheet had a large EVOf (layer thickness support ratio of 38 inches) and was not only non-uniform, but also had streaks and spots that were noticeable after 3 to 4 hours of film formation. As a result of carrying out deep drawing molding in the same manner as in Example 3 for a portion with a small diameter, many elongation irregularities were observed on the side surfaces of the molded product.Therefore, a product that was visually acceptable for use could not be obtained.

Comparative Example 8 To 100 parts by weight of EVOH used in Comparative Example 6, 10 parts by weight of diethylene glycol was added as a plasticizer, and 4
The pellets were formed into pellets using a 0φ extruder at a die temperature of 220°C. After drying this pellet at 95° C. for 16 hours, coextrusion film formation was performed in the same manner as in Example 3. The thickness variation rate of the obtained sheet was 45 inches, showing almost no improvement, and to make matters worse, after 3 to 4 hours, uneven running, streaks, etc. began to occur frequently. When a portion with a relatively uniform thickness distribution was sampled and deep drawing was performed in the same manner as in Example 3, the elongation unevenness was somewhat improved. However, the oxygen permeation rate of this container is 240cc・20μ/n+'
-24hr-atm (20°C-1004RH), which was too large to withstand use as a gas barrier container.

Example 4 In Example 2, the ethylene pressure in the polymerization tank was set to 35 KP/c.
rlG, vinyltriethoxysilane is used as silicon-containing olefinically unsaturated monomer, and the supply amount is 10
The same procedure was carried out except that the setting was 0 η/hr. The obtained copolymer contained o, o o s mole % of vinyltriethoxysilane units, 72 moles of vinyl acetate units, and about 28 moles of ethylene units. Modified EVOH was obtained according to Example 2. The degree of saponification is 99.4 molti,
Melt viscosity index M measured at 210°C, 2,16 (l load)
21o was 0.80f/10min ○ The EVOH, polyester (Nippon Unipet RT533
) and adhesive resin (Mersene M5420 manufactured by Toyo Soda (
Maleic anhydride kraft polypropylene) was fed to a spine flow type 315-layer coextrusion pipe forming machine, and PET/AD/5i-EVOH/AD was processed using a die temperature of 270°C and a pipe take-off device of 0,6,/min.
/PET structure, total thickness 3m/m.

A pipe with an outer diameter of 30 m/m was obtained. The thickness of each layer is
The PP layer is about 1200μ each, the AD layer is about 150μ each,
The EVOH layer is approximately 200μ. E of the cross section of this pipe
The thickness distribution of the VOH layer was uniform as seen under a microscope (xlOO magnification), and there were no visible streaks, bumps, or flow irregularities in the flow direction of the pipe (approximately 24 hours of continuous operation). ). This pipe was cut, a mouth and a bottom were formed to make a parison, and then heated to 100° C. and then applied to a biaxial stretching blower to make a container. A good bottle with no cracks in appearance was obtained.

Comparative Example 9 The same procedure as in Example 4 was carried out except that vinyltriethoxysilane was not used in Example 4, but ethylene was included! 2
8.3 mol%, saponification degree 99.5 mol%, MIt90
2.3? / 7joe got 0 EVOH for 10 minutes.

A pipe was formed using EVOI (EVOI) in the same manner as in Example 4, and when the cross-sectional EVOI (layer) was observed, several local thickness unevenness was observed.
Streaks and uneven flow in the VOH layer were observed.

When this pipe was stretch blow molded in the same manner as in Example 4,
Vertical streaks on the bottle surface, especially near the mouth (shoulder)
A striped thickness unevenness was observed on the surface, and the material was unusable.

Example 6 In a polymerization tank with a capacity of 509 mm and equipped with a stirrer and internally equipped with a cooling coil, polymerization was carried out in a batch manner under the conditions shown below to obtain a silicon-containing ethylene-vinyl acetate copolymer.

Vinyl acetate charge 15 - Methanol charge t 5.8 Kp Rubinyltrimethoxysilane charge 6.4t 2.2-
Azobisisobutyronitrile charge amount 2,7f Polymerization temperature 60℃ polymerization tank Ethylene pressure 33ψL Polymerization time
6.5 hr Polymerization rate of vinyl acetate is 31
It was Chi. It was confirmed by nuclear magnetic resonance analysis that the copolymer contained 0.02 moles of divinyltrimethoxysilane units, 68 moles of vinyl acetate units, and 32 moles of ethylene units. The product was saponified and isolated in the same manner as in Example 1, subjected to one post-treatment, and then dried to obtain modified EVOH. Saponification degree is 99.5 mol%, MI□. is 0.55
f/10 minutes.

ggvou, polyester (Japan Unibet RT335
) and an adhesive resin (Toyo Soda 1i'L5420) in the same manner as in Example 4 to obtain a coextruded sheet.

The thickness of each layer is 500μ for each PET layer, 50μ for the adhesive layer,
and the EVOH layer is about 50μ. The thickness variation rate of this sheet was 7%, and there were very few streaks, uneven flow, spots, etc. even after 24 hours of continuous operation. The obtained sheet was stretched using a pantograph type biaxial stretching device (Toyo Seiki, K,
) to perform sequential biaxial stretching of 3x3 times at a sheet temperature of 95°C. The volatile content of the EVOH layer at this time is 0.18%
The co-stretched film had almost no cracks, uneven thickness, etc., had a uniform thickness, and was very good. After this film was heat-set at 220°C and 140°C in an air bath with a constant width, the amount of oxygen permeation through the EVOH layer of the film was measured and found to be 0.3 cc ・20μ/n?・24 hours
-atm (20℃-65%RH), 18cc20μ/&
・24hr-atm (20℃-io.

%RH) and exhibited very good gas barrier properties.Comparative Example 10 The same procedure as in Example 6 was conducted except that vinylmerxysilane was not used, and the ethylene content was 31.
8 mol %, saponification degree 99.6 mol type M1 go 5.
I S' / 10 minutes + 7) Get EVOH fCo (
7) Coextrusion molding was carried out using EVOH in the same manner as in Example 6, but the thickness variation rate of the EVOH layer was 36 inches, which was unfavorable. Further, when biaxial stretching was performed in the same manner as in Example 6, slight unevenness in stretching was observed in some parts, making it unusable. There was also the problem that there was a high probability of tearing during stretching, probably due to variations in the thickness of the EVOH layer. E before stretching
The water content of the VOHr value was 0.21%. Example 7 Using the same polymerization tank as in Example 1, continuous polymerization was carried out under the conditions shown below.

Vinyl acetate supply amount 400 f/hr Methanol supply f 100 r/hr Vinyltrimethoxysilane 240 ■/hr 2.2-
Azobis-(2,4-dimethylbale cr=tri/')
1701#W/hr polymerization temperature
60℃ average residence time
5 hr Polymerization tank ethylene pressure 46
The polymerization rate of Kp/dG vinyl acetate was about 45%.

The copolymer was determined by nuclear magnetic resonance analysis to contain 0.023 mol of vinyltrimethoxysilane units and 6 mol of vinyl acetate units.
It was confirmed that it contained more than 1 mole of ethylene units, and about 39 moles of ethylene units.

After saponification, isolation, post-treatment in the same manner as in Example 1, and drying, modified EvOH was obtained. Saponification degree is 99.
4 molti, MI, o was 1.5 f/10 min.

The EVOH1 saturated polyester (PE made by Eastman Co., Ltd.)
T-G9921), two types and three layers co-injection molding machine (8 precision A
0FET/5i supplied to SB) to create a multilayer parison
-EVOH/PET Components (Q each layer) The thickness of the Miha PET layer was 1200 μm, and the EVOH layer was 200 μm. The thickness distribution of the EVOH layer in the cross section of this pipe was examined using a microscope (xl
It was uniform as far as it was seen under OO times).

This parison was heated to 105°C and subjected to biaxial stretching blow molding equipment (Nissin ASB) to create a container.
A good bottle without cracks was obtained.

Comparative Example 1 Example 7 was carried out in the same manner as in Example 7 except that vinyl trimethoxy 77 run was not used.Contains ethylene! 3
9 mol%, saponification degree 99.4 mol M'190 1-5
t / 10 minutes of EvOH obtained. When a parison was made using Kono EvOH to the same depth as in Example 7 and stretch blow molding was performed, there were vertical streaks and cracks on the bottle surface, as well as streak-like uneven thickness, especially in the area near the mouth (shoulder). It was recognized that it could not be used.

Claims (4)

[Claims] (1) Vinyl acetate, ethylene and the following general formula (I),
Saponification degree of vinyl acetate component obtained by saponifying one or more copolymers selected from silicon-containing olefinically unsaturated monomers represented by (II) and (III): 95 mol% or more, ethylene content 25-60 mol%
, a coextruded gas barrier multilayer having a saturated polyester resin or polyamide resin layer on at least one side of a layer made of a saponified silicon-containing ethylene-vinyl acetate copolymer having a silicon content of 0.0005 to 0.2 mol%. Structure. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) [However, here n is 0 to 1, m is 0 to 2, R^1 is a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, R^2 is an alkoxyl group having 1 to 40 carbon atoms, and the alkoxyl group is an oxygen-containing substituted It may have a group. R^3 is hydrogen or a methyl group, R^4 is hydrogen or a lower alkyl group, R^5 is an alkylene group or a divalent organic residue in which chain carbon atoms are interconnected by oxygen or nitrogen, and R^6 is Hydrogen, halogen, lower alkyl group, allyl group, or lower alkyl group having an allyl group, R^7 is an alkoxyl group or an acyloxyl group (here, an alkoxyl group or an acyloxyl group may have a substituent containing oxygen or nitrogen) good), R
^8 is hydrogen, halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, and R^9 is a lower alkyl group. ] (2) The gas barrier multilayer structure according to claim 1, wherein the multilayer structure is a heated and stretched food packaging container. (3) The gas barrier multilayer structure according to claim 1, which is a shrinkable film for food packaging that is subjected to a rapid cooling treatment immediately after the multilayer structure is heated and stretched. (4) The gas barrier multilayer structure according to claim 1, which is a co-stretched film for food packaging which is heat-stretched and fixed by heat treatment.