JPS61290048A - 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 barrier that is free from uneven thickness and streaks during coextrusion molding, and free from pinholes, cracks, and local uneven thickness during hot stretching. The present invention relates to a multilayer structure with excellent properties.

Saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH)
are now recognized as having 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 EVOLL lack toughness, are brittle, and have drawbacks such as not exhibiting effective barrier properties against water or water vapor. To improve these drawbacks, EVOH resins are usually made of nylon, polyester, polypropylene,
Thermoplastic resins such as polyethylene and polyvinyl chloride
It is used in the form of a multilayer film formed by laminating a structural layer containing one or more types of t and various types of thermal ξ-lunt layers represented by ionomers, ethylene-vinyl acetate copolymers, etc.

However, due to recent technological advances, multilayer structures containing EVOH' are often manufactured by a coextrusion method in which various resins are extruded simultaneously from a number of extruders and a multilayer laminate is obtained from a single die. Further, in order to increase the strength of the multilayer structure, stretching may be performed using a heating device. However, during such molding processing, the following problems arise due to the presence of EVOHi, and it is often difficult to use it as a food packaging material.

That is, when molding a multilayer structure containing Evon2 by coextrusion, hvoii and polypropylene,
Perhaps because the viscosity properties are vastly different from polystyrene, even if the overall thickness and distribution of the multilayer structure is made uniform, the thickness distribution of the nvon layer is not uniform, ensuring barrier properties as a gas barrier food packaging material. Therefore, it is necessary to make the EVOH layer thicker than necessary.

Furthermore, due to the non-uniform thickness of the EVOH layer, the gas barrier properties often deteriorated significantly due to cranking and local thickness unevenness during heating and stretching. What is worse is that during coextrusion molding, if the EVO is operated for a long period of time, minute streaks and spots may occur in one layer, which not only spoils the appearance, but also causes EV during heating and stretching.
OH cracks, bumps, and minute thickness deviations increase, gas barrier properties deteriorate, and the product becomes unusable as a food packaging material.

On the other hand, even if we improve the molding conditions and molding equipment to make the thickness distribution of the EVOH layer as uniform as possible, even in sheets made by laminating Evon sheets with uniform thickness by dry lamination, EVOH often occurs during heating and stretching.
In some cases, the gas barrier properties deteriorated significantly due to cracks in the layer, local thickness unevenness, etc., and the product became unusable. Conventionally, in order to equalize the thickness distribution during coextrusion molding, methods have been used to select brands of polypropylene, polystyrene, and adhesive resins whose melt viscosity (melt index; MI) is close to EVOH, and to modify the coextrusion equipment. However, regarding the former, the shear rate dependence of viscosity is essentially different between EVOIII and other resins, so even if the viscosity (melt index)′ft under a constant shear rate condition is combined, the thickness distribution Significant improvements are not possible, and the viscosity of polypropylene, polystyrene, and adhesive resin is regulated, so there is a problem that the desired food packaging material cannot be obtained. On the other hand, due to modification of coextrusion equipment, EVOH
In some cases, a uniform layer can be obtained, but because the operating conditions are very narrow, the thickness distribution changes due to slight fluctuations in discharge speed and discharge temperature, making stable production difficult and requiring changing the brand of resin. In this case, it was necessary to extensively modify the device itself through trial and error, and there were major problems such as the need for a large amount of labor, time, and raw materials to establish the conditions.

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. In other words, polyamide resin is EVOfl
When blending the polyamide resin with EVOI to obtain a multilayer structure, the polyamide resin reacts with E VOI, and a large number of gel-like substances (fish eyes) are generated in the molded product, and the product is heavily colored and cannot be used. When the structure is made into a container by secondary molding, in order to prevent the occurrence of cracks, pinholes, etc. in the gvon layer (the content of polyamide resin to be added is 10 to 30 parts by weight per 100M parts of EVOH). As a result, the gas barrier properties are drastically reduced, and even if the molded container is good, it cannot be used in the food packaging field, which is characterized by high gas barrier properties. Hydroxyl group-containing plasticizer systems also need to be added in an amount of 10 to 20 parts by weight per 0 parts of EVOHI O, similar to polyamide resins, and the gas barrier properties are greatly reduced. , plasticity that is not sufficiently compatible with EVOH bleeds, and the adhesive strength between the EVOH layer and other resin layers in a multilayer laminated container decreases significantly over time, damaging the shape of the container. Additives are difficult to use.Therefore, there is no significant deterioration in gas barrier properties, and when a multilayer structure is formed by coextrusion, the thickness of the EVOIL layer is uniform, and the multilayer structure When heating and stretching the body, EVO
One of the important issues is the development of EVOIi that has good moldability and does not cause pinholes, cracks, or minute thickness deviations in the H layer.

The present invention provides a product that is free from the above-mentioned defects, has no unevenness between products and within a molded product, and is therefore free from variations in each of the above-mentioned properties.
Modified silicon-containing EVOHi with extremely high uniformity
It is intended to use this method to obtain a coextruded multilayer structure.

Means for solving the D0 problem The present invention provides a melt molding material made of EVOIL 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 tIl, (
Saponification degree of vinyl acetate component obtained by saponifying a copolymer of one group or two or more selected from silicon-containing olefinically unsaturated monomers represented by IIl and field: 9
5 mol% or more, ethylene content 25-60 mol%, preferably 25-55 mol%, silicon content o, o o o
It is a coextruded multilayer structure having a polypropylene resin or polystyrene resin layer on at least one side of a silicon-containing EVOH layer having a silicon content of s to 0.2 mol %.

When creating a volatile laminated multilayer structure having a polypropylene or/or polystyrene layer on one or both sides of the EVOH layer via an adhesive resin by coextrusion, various brands and viscosities of the adhesive resin, polypropylene, and polystyrene may be used. Even if you change the structure and flow rate of the resin flow path of the coextruder, it is very difficult to make the thickness distribution of the EVOH layer uniform in the direction perpendicular to the direction of resin discharged from the coextruder die. It was difficult. As a result, there were many problems such as cracks during heating and stretching due to uneven thickness distribution of the EVOH layer, and a decrease in gas barrier properties due to local unevenness in thickness. .

The root cause of the above problem was thought to be that the shear rate dependence of the viscosity of polypropylene, polystyrene, and adhesive resins was different from that of EVOH resin, so we modified EVOH with various ladder additives (plasticizers, crosslinkers, etc.). and modification by changing the copolymer composition. As a result, although polyhydric alcohol plasticizers 1, carboxylic acid amide plasticizers, aromatic sulfonic acid plasticizers, etc. have the effect of lowering the viscosity, the effect of improving the thickness distribution of the EVOIL layer is small and is not practical. . In addition, the method of changing the shear rate dependence of viscosity by adding peroxide and crosslinking Evon1 was found to be somewhat effective, but it appeared to be unusable due to the appearance of bumps and uneven flow during long-term operation. Ta. However, surprisingly, silicon-containing EVOH
Single and other plasticizers, crosslinking agents, added EVOI (compared to the composition), the EVOH layer not only has a uniform thickness distribution, but also has very good properties with almost no bumps, streaks, or uneven flow during long-term operation. What is even more surprising is that when a multilayer structure having a polypropylene or polystyrene layer in the EVOH layer is heated and stretched, EVOH alone or EV containing other plasticizers, etc.
Along with the OH composition, not only can a very good molded product with almost no pinholes, cracks, or minute thickness deviations in the E YOU layer be obtained, but the gas barrier properties of the molded product, especially under high humidity, can be improved. It was found that this material has excellent properties, leading to the present invention. The reason why silicon-containing EVOH has the above-mentioned completely unexpected moldability improvement effect is not obvious, but low polymerization degree EVOH containing silicon compounds
is partially and reversibly crosslinked via a silicon compound, so 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. This is thought to be because the shear rate dependence of viscosity and radiation stress characteristics match those of the EVOH resin, making it easier to make the thickness distribution of the EVOH layer uniform during coextrusion molding. In addition, the problems that occur during long-term operation,
The gelation of EVOH, which causes streaks and uneven flow, is also thought to be a characteristic of EVOR with a low degree of polymerization. That is, although the apparent viscosity shows a predetermined value due to partial and reversible crosslinking of the silicon compound, it is substantially
The generally accepted fact that low polymerization degree resins are difficult to gel supports the above reasoning (specificity of silicon compounds). Furthermore, the moldability improvement effect in hot stretching processing is also due to the partial, reversible crosslinking effect of silicon compounds, as described above.In other words, during high-speed deformation (stretching), it appears to act as a low molecular weight resin and facilitates deformation, while crosslinking This is thought to be due to the fact that the strength of the high molecular weight component is taken into account, so the stretchability is greatly increased.

F9 More detailed description of the invention The melt-molded material made of EVOH in the present invention has an ethylene content of 25 to 60 mol%, preferably 25 to 55 mol%, and the degree of saponification of the vinyl acetate component of the copolymer is An ethylene content of 95 mol% or more is preferable, and if the ethylene content is less than 25 mol%, it is difficult to greatly improve the effect of improving moisture dependence of barrier properties against oxygen, etc. while maintaining good melt molding processability. On the other hand, if it exceeds 55 mol%, especially 60 mol%, the barrier properties against oxygen, etc. and the fragrance retention properties, which are the characteristics of EVOH, will decrease. If the degree of saponification is less than 95 mol %, the barrier properties and oil resistance will deteriorate, making it impossible to maintain the original characteristics of EVOH and making it difficult to enjoy the effects of the present invention.

The silicon-containing olefinically unsaturated monomer used in the present invention is preferably one or more selected from compounds represented by the following general formulas CI), (ID and (2)). It can be used for.

[However, here, n is O~1, m is O~2, Bt is a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, and R2 is a saturated branched or unbranched alkoxyl group having 1 to 40 carbon atoms. and the alkoxyl group may have an oxygen-containing substituent. B3 is hydrogen or a methyl group, B4 is hydrogen or a lower alkyl group, B5 is an alkylene group or a divalent organic residue in which chain carbon atoms are interconnected by oxygen or nitrogen, W is hydrogen, halogen,
A lower alkyl group, a 7lyl group, or a lower alkyl group having an allyl group, B7 is an alkoxyl group or an acyloxyl group (here, the alkoxyl group or acyloxyl group may have a substituent having oxygen or nitrogen.)
, R8 is hydrogen, halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, and B9 is a lower alkyl group. ] In more detail, B1 is a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms,
or 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms
B4 represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and B5 represents an alkylene group having 1 to 5 carbon atoms or a divalent group in which chain carbon atoms are bonded to each other by oxygen or nitrogen. B6 is hydrogen, a halogen, a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a lower lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms. It represents an alkyl group, and B7 has 1 or more carbon atoms.

40 flukoxyl or acyloxyl group (herein, the alkoxyl group or acyloxyl group may have a substituent having oxygen or nitrogen), B8 is hydrogen, halogen, a lower alkyl group having 1 to 5 carbon atoms, Allyl group having 6 to 18 carbon atoms or lower alkyl group having 1 to 5 carbon atoms having all allyl groups having 6 to 18 carbon atoms (7, B9 represents a lower alkyl group having 1 to 5 carbon atoms).

The silicon-containing olefinically unsaturated monomers represented by general formula (■)c include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxy7rane, vinyltriethoxysilane, vinylmethyljethoxysilane, and vinyldimethylethoxysilane. Silane, allyltrimethoxysilane, allylmethyldimethoxysilane, allyldimethylmethoxysilane, allyltriethoxysilane, allyldimethylethoxysilane, vinyltris(β-
methoxyethoxy)silane, vinylisobutyldimethoxysilane, vinylethyldimethoxysilane, vinylmethoxydibutoxysilane, vinyldimethoxybutoxysilane, vinyltributoxysilane, vinylditoxydihexyloxysilane, vinyldimethoxyhexyloxysilane, vinyltrihexyloxysilane, Vinyldithoxyoctyloxysilane, vinyldimethoxyoctyloxysilane, vinyltrioctyloxydinone, vinylmethoxydioleyloxysilane, vinyldimethoxyoctyloxysilane, vinylmethoxydioleyloxysilane, vinyldimethoxyoctyloxysilane, general formula CH2-CH2i
-((0CH20H2%OH), -m)(OCH3)
Examples include polyethylene glycol derivatives of vinylmethoxysilane represented by m (where m is the same as above, and X represents 1 to 20), but vinyltrimethoxysilane is preferred from an economic standpoint.

As the silicon-containing olefinically unsaturated monomer represented by the general formula (II), 3-(meth)acrylamide-propyltrimethoxysilane CH2=CBCNH(OH2)38t (001(3
)33-(meth)acrylamide-propyltriethoxysilane CR2=(E BONH(CH2)3 S t (0O
H20k13)33-(meth)acrylamitope p
Piltri(β-methoxyethoxy)silane CH2= CEONfi (CH2)3 S t (0
0H201 (20C(I3)33-(meth)acrylamido-propyltri(N-methylaminoethoxy)silane CH2=OBONR(OH2)38i (00H2C
H2NH(J3)32-(meth)acrylamide-ethyltrimethoxysilane CHz = OBCNH(Cl12)281 (0C
Hs )31-(meth)acrylamide-methyltrimethoxysilane CH2=CBONHCH2S i (OCH3)32-
(Meth)acrylamido-2-methylpropyltrimethoxysilane (XJI.

CH2=CFONHOCH28i (ucH3).

:11 0H3 2-(meth)acrylamide-direct button or branched alkyltrialkoxysilane N-(2-(meth)acrylamide-) such as isopropyltrimethoxysilane (B represents hydrogen or methyl group) Ethyl)-7 Minopropyltrimethoxysilane CHz = 0BOONHCHzCHzNH(0k12
) a S 1 (OCH3) a (3-(meth)acrylamido-propyl)-oxypropyltrimethoxysilane Cl12=O1ICONIII(CH2)s O(OH
2) (meth)acrylamide-nitrogen-containing or oxygen-containing alkyltrialkoxysilane 3-(meth)acrylamide-propyltriacetoxysilane OH2= such as 3Sl(00”3)a (B represents hydrogen or a methyl group) Cl100NH(OH2)381 (0CO
Of13 ) 32-(meth)acrylamide-ethyltriacetoxysilane CH2=OBOONH(OH2)28 i (0C00
H3) 34-(meth)acrylamido-butyltriacetoxysilane OH2” OHOONI((CH2)48 l (0C
OOH3) 33-(meth)acrylamide-propyltripropionyloxysilane an2=cnco dish (OH2) 38 i (QCOC■
2C)13)32-(meth)acrylamido-2-methylpropyltriacetoxysilane k13 0H2=O1iCONHOOH28i(OCOCH3)
Book 3 CH3 N-(2-(meth)acrylamido-ethyl)aminopropyltriacetoxysilane 0Hz=cbcoNHcnzcu2Nn(an2)38
(meth)acrylamido-alkyltriacyloxysilane such as t (000(3H3)3 (B represents hydrogen or methyl group), 3-(meth)acrylamido-propylisobutyldimethoxysilane Ok+2 = CBOQNH(OH2)38 i ( 00
H3)2■ 0ffpHCH2Cfi3 2-(meth)acrylamide-ethyldimethylmethoxysilane CH3 CH2=CROONH(OH2)2 S r 00H3
CH3 3-(meth)acrylamide-propyloctyldiacetoxysilane OH2= CBCONH(OH2)38 Amount (0000
H3) 2((J2), (J3 1-(meth)acrylamide-methylphenyldiacetoxysilane CH2=CEC0NHOH281(01jOOH3)2
3-(meth)acrylamide-propylbenzyljethoxysilane CH2=OBCONH(0IE12)38i(0
GH20) 2c++2-0. l115 2-(meth)acrylamido-2-methylpropylmonochlorodimethoxysilane CH2=C)ICONHC(CR3)20H28i (
0Ofi3)2CI! (meth)acrylamidoalkyl di- or monoalkoxy or di- or monoacyloxysilane such as 2-(meth)acrylamido-2-methylpropylhydrodienemethoxysilane H3 H3K (B represents hydrogen or methyl group), 3 -(N-methyl(meth)
acrylamide)-propyltrimethoxysilane (J2=OBCON (0M2)38 i (0CHa
).

CH3 2-(N-ethyl-(meth)acrylamide)-dityltriacetoxysilane (3H2=0BONCk120 to 281(OCOCH
3) (N-alkyl-) such as 3H2CH3 (B represents hydrogen or methyl group)
Examples include (meth)acrylamido)alkyltrialkoxy 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-methylpropyltriacetoxysilane are preferably used because the amide bond is extremely stable against acids or alkalis. Here, the modified silicon-containing EVOH obtained by copolymerizing the silicon-containing polymerizable monomer represented by the general formula (■) with vinyl acetate and ethylene and saponifying the resulting copolymer is obtained by the following general formula (■). Contains a copolymerized unit represented by .

(B3, B4, B5, B6, m are the same as above.B
IO is a hydroxyl group, represented by the general formula OM, and a salt of the hydroxyl group (M is an alkali metal or all N1f4) fc. ) As the silicon-containing olefinically unsaturated monomer represented by the general formula (IID), vinyltriacetoxysilane OH2=OH81(0OCf4)3vinyltripropionyloxysilane OH,=CH8i(0COH2Cl).

Impropenyltriacetoxysilane CH2=08i (OCCH3)3 Vinylisobutyldiacetoxysilane CH2-CrH8i (000CH3)2(J3
CHCH3 Vinylmethyldiacetoxysilane OH2= OIisi( OCOCH3 )2OH3 Vinyldimethylacetoxysilane OH3 0H,0 Vinylphenyldiacetoxysilane 01:I2=CH8 i ( 00(J3)2 I
I Vinyl monochlorodiacetoxysilane lO Vinyl monohydrodiene diacetoxysilane O etc., but vinyltriacetoxysilane is preferred from an economic standpoint.

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 EVOH is mainly determined by 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. The silicon content of the modified EVOH is mainly controlled by the relationship between the vinyl acetate and the silicon-containing olefinically unsaturated monomer present in the system. It is well known that in the batch method, the copolymer composition changes with the polymerization rate according to the copolymerization reactivity ratio, but one or both monomers are added to keep the monomer composition constant. In order to obtain a copolymer with a uniform copolymerization composition, it is necessary to adopt the so-called semi-batch method.
Chemistry) vol, 49, %2,
208-209 (1957). In the case of a continuous system, a completely mixed one-stage flow system reaction system in which the stirring mixing tank is a common reaction tank is most suitable, and in the case of a multi-stage flow system reaction system of two or more stages, the above For the same reason as above, it is more preferable to add monomers 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-2,4-dimethylvaleronitrile), 2,4.4-)limethylvaleronitrile,
2. Nitriles such as 2'-7zobisisobutyronitrile, di-n-propylperoxycarbonate, bis-
Known carbonates such as 4-t-butylcyclohexyl peroxydicarbonate and bis-2-ethylhexyl peroxydicarbonate, peroxides such as acetylcyclohexane sulfonyl peroxide, benzoyl peroxide, and lauroyl peroxide. Radical initiators can be used. In particular, polymerization initiators with shorter half-lives are effective in long-term continuous polymerization in that they can almost completely or to a large extent suppress the formation of gel-like substances that are observed over time during copolymerization and are insoluble in the polymerization system. Suitable for use in operations.

The copolymer obtained by polymerization is then subjected to a saponification reaction. The saponification reaction is advantageously carried out in a known manner, for example by 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. In particular, using a basic reactor as disclosed in Japanese Patent Nos. 575,889 and 611,557, methyl acetate 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. The most suitable method can be used.

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. Among these, sodium hydroxide is industrially and economically advantageous. Saponification temperature is 60~
Suitably selected from the range of 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, the copolymer containing the monomer represented by the above general formula (I[) is stable because the amide bond of the silicon-containing polymerizable monomer unit does not decompose in the saponification reaction with an alkaline catalyst. is maintained. 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 (IO) are simultaneously partially or highly saponified and converted into hydroxyl groups or alkali salts of hydroxyl groups. Furthermore, some of these hydroxyl groups are present in the modified EVO obtained after the saponification reaction.
When drying the H molding material, these reactive groups may be bonded together to form siloxane bonds depending on the drying conditions. The modified EVOH molding material with a large number of siloxane bonds may have poor thermal melting properties, so in such cases, the content of silicon-containing monomers should be adjusted or silicon-containing polymerizable monomers may be added. It is preferred that the modified EVOH molding material has a 1 (meth)acrylamide-branched alkylsilane unit, which has extremely high stability against alkali, as a mer unit.

After the saponification reaction, the modified EVOI (molding material can be isolated by any known method, but the polymer can be separated by precipitating it in the form of a strand as disclosed in Japanese Patent No. 725,520). The precipitated and isolated EVOH molding material is washed with water by a known method, and then
Perform a known heat stabilization treatment such as acid treatment and dry. During the saponification reaction during the acid treatment, the silicon-bonded alkoxyl group, carboxyl group, hydrogen, and halogen are converted into an alkali salt of the hydroxyl group, resulting in a hydroxyl group.

The modified silicon-containing gvon according to the present invention is EVOH
This is extremely satisfactory from the viewpoint of improving the inherent properties of the resin and imparting properties that are compatible with other resins and processing methods. Accordingly, the modified EVOH melt molding material suitable for each case can be obtained, and when composited with other resins having a low melt viscosity index, the difference in melt viscosity is large and the phenomenon of melt viscosity inconsistency is observed. It is often encountered in cases where
In such a case, the melt viscosity mismatch can be resolved by using the modified EVOH resin molding material in which the melt viscosity index of the EVOfi resin is lowered by the modification of the present invention while maintaining the composition. The usefulness of the molding material is extremely great, coupled with 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 large, the degree of crosslinking will increase too much and heat infusibility will develop. The content is selected depending on each purpose, but is preferably in the range of 0.0005 to 0.2 mol%, particularly 0.001 to 0.1 mol%. Here, silicon content refers to silicon-containing monomer - vinyl acetate -
Amount of silicon-containing monomer in ethylene copolymer (mol%)
means.

The modified silicon-containing EVOH of the present invention can be used more satisfactorily for all conventional purposes.
As mentioned above, the new properties derived from the silicon content, such as improved adhesion to aluminum foil, other resins, etc., can be utilized to full advantage.

A8TM, D-1 of modified EVOH in the present invention
238-Melt viscosity index measured by 'I' R/
'-ro γte=nogu person (shikogo material pressure) o at 190℃, load i2,160g,
o s g/lo minutes or more, roughly 0.05 to 10 g/lo
10 minutes is preferable, especially 0.1-10g/10
For various applications such as films, sheets, containers, etc., the film is preferably used unstretched or at least uniaxially stretched.

The silicon-containing EVO1i of the present invention is made from EVOR 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 $3 substance include α-olefins having 3 or more carbon atoms, acrylic acid, methacrylic acid, and esters of these acids. Also, this silicon-containing E
It is free to mix ordinary EVOH into VOI-1 to the extent that it does not impede the purpose of the present invention.

As mentioned above, the silicon-containing EV OHo of the present invention is used in combination with polypropylene resin or polystyrene resin, but in recent years, along with the diversification of properties and higher quality required, various other The combination of all the resins can be suitably used as a two-layer structure or a multilayer structure of two or more layers.

When compounding, a coextrusion method is used, but in this case, an EVOR with a desired ethylene content that does not cause melt viscosity mismatch with polypropylene resin or polystyrene resin can be obtained by appropriately selecting the silicon content. reactor. The layer structure of the multilayer structure is, for example, polypropylene (hereinafter referred to as PP)/adhesive layer/silicon-containing EVOfi (1
'↓ below 8i-EVOH), PP/adhesive layer/8i
EVOH/adhesive layer/PP-PP/adhesive layer/8i-E
VOH/Contact M layer/PE, PET/Adhesive layer/8i-EVO
H/adhesive layer/PP, polystyrene (hereinafter referred to as PS)/
Adhesive layer/5i-EVOL (, PS/Adhesive layer/8i-EV
Examples include On/adhesive layer/P8.

The adhesive resin used for the adhesive layer varies depending on the type of resin laminated adjacent to the 18i-EVOH, but for example, maleic anhydride graft-modified PE, maleic anhydride graft-modified PP, maleic anhydride graft-modified ethylene-
Ethyl acrylate, ethylene-vinyl acetate copolymer,
Examples include a mixture of one or more weights selected from maleic anhydride graft-modified ethylene-vinyl acetate copolymers, or a blend of these and 8i-EVOH.
It is possible to select and use one of these.

When commercializing the dam layered tank structure into containers, etc., it is economically important to reuse the waste and rejected products of the laminate produced during molding, but it is economically important Blend with other resins and/or adhesives, all alone or
It can be used by laminating with 8i-EVO or other thermoplastic resins.

In the present invention, the polypropylene resin used is a homopolymer, a copolymer, or a blend thereof with propylene as a main component or with other polymers. Suitable propylene polymers include isotaft ivy polypropylene, crystalline propylene-ethylene copolymers, blends of polypropylene and propylene-ethylene copolymers or polyethylene, and crystalline propylene copolymers and polyethylene copolymers. Blends of these can be mentioned. The amount of ethylene units contained in the propylene polymer in the form of a copolymer or blend is preferably 20% by weight or less, particularly 10% by weight or less.

The polystyrene resin in the present invention refers to a resin containing at least -cH-CH2 structural units represented by the following general formula.
-3-tZ)p is a resin containing 25% by weight or more. (Here, B is a hydrogen atom or a methyl group, 2 is a halogen atom or a methyl group, and p is 0 or an integer of 1 to 1.) Specifically, polystyrene, rubber-modified polystyrene, styrene-acrylonitrile, etc. Polymers, homopolymers and copolymers of styrene and its derivatives, exemplified by styrene-butadiene=7crylonitrile copolymer and the like. Blends of these resins with styrene-conjugated diene block electroconductive rubber and its water agent are also applicable.

In the present invention, as a method for obtaining a multilayer structure, 8i-E
A method of forming VOH and polypropylene or/or polystyrene resin into a coextrusion sheet via an adhesive resin (feed block method or multi-manifold method), a method of coextrusion lamination, a method of making a coextrusion sheet, and a method of creating a coextrusion pipe. or a method of creating a parison by co-injection molding, or a method of reheating and stretching the laminate thus obtained by vacuum pressure deep drawing, biaxial stretching molding, biaxial stretching blow molding, etc. can be given. There are no particular limitations on the thickness structure of the multilayer structure of the present invention, but when considering moldability, cost, etc., the thickness ratio of the EVOH layer to the thickness of all layers is 2 to 2.
Approximately 20% is suitable.

Further, in the present invention, there is no particular restriction on the water content of the 8i-EVOH layer, which is a component of the multilayer structure, during heating and stretching, but it is preferably within 0.01 to 10%.

In the thus obtained multilayer structure of the present invention and its heated stretched product, the thickness of the 5i-EVOH layer is uniform, and there are no streaks or
There are no lumps, and there are no pinholes, cracks, or uneven thickness that tend to occur during stretching, so the gas barrier properties are extremely good. Therefore, it is useful as food packaging materials, containers, or containers that require gas barrier properties.

EXAMPLES Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited thereto in any way. (In addition, the middle part of the examples or % indicates parts by weight or weight % unless otherwise specified.) Measurement of thickness distribution of coextruded product> In a feed block type 3-shelf 5-layer coextrusion device, the material was discharged from a die width of 550α. PP/MuD1EVOH/A
D, / P P or P S /A D2/EVOH/
A D2/P 8 sheets (PP, AD, P8 brands,
(See below for thickness) The film was formed at a take-up speed of f I Vlrnin.

If the thickness of the EVOH layer in the center of the above sheet is Aμ, and the average thickness of 10 CIH left and right from the center is Bμ, then EVO
H layer (7) Thickness variation rate (X%>fX=cB-A)/A×
It is defined as 100 er.

P8...Polystyrene (Idemitsu Styrene ET-6
1) 450μEvon, ・Target center thickness 50μ <Method for measuring moisture in EVOH layer> Peel off the EVOH layer on the multilayer structure just before heating and stretching, and leave it in a hot air dryer at 120℃ for 24 hours to reduce weight. Determine the moisture content of the EVAL layer. This value is expressed as a percentage and is referred to as volatile content.

Example 1 Continuous polymerization was carried out under the conditions shown below in order to obtain a silicon-containing ethylene-vinyl acetate copolymer in a polymerization tank with a capacity of 101 cm and equipped with a stirrer and internally equipped with a cooling coil.

Vinyl acetate supply amount 480 g/h
rMethanol supply amount 40 g/
hr bivinytrimethoxysilane supply 3s 5
■/hr2.2'-azobisinbutyronitrile
33■/hr Polymerization temperature
77℃ polymerization tank ethylene pressure
e okg/dG average residence time
The polymerization rate of 6 hrs vinyl acetate 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 45% methanol-soluble Fi of the copolymer. According to the magnetic resonance analysis, the copolymer contained 0.027 mol% of vinyltrimethoxysilane units and vinyl acetate units.
It was confirmed that it contained 59.5 mol% of i and about 40.5 mol% of ethylene units. Introducing a methanol solution of the copolymer into a basic kephization reactor, further supplying sodium hydroxide to the reactor such that the molar ratio to the vinyl acetate component contained in the copolymer is 0.05, Methanol vapor is blown into the bottom of the column, methyl acetate as a by-product is removed from the top of the column, a saponification reaction is carried out, and reforming E is introduced from the bottom of #E.
A methanol solution of VOH was obtained. i in the methanol solution
After blowing in a mixed vapor with a methanol/water ratio of 7/3 to change the solvent composition in the solution to a yK/methanol mixed system, the solution was discharged in the form of a strand into a 10% aqueous methanol solution at 5°C for solidification and precipitation. the EVOI (
The pellets were isolated as pellets, washed with water for 90 minutes, immersed in dilute acetic acid, and dried at 65°C to 110°C. The degree of saponification was 99.3 mol%.

The EVOfi, polypropylene (Mitsubishi Noblen MA-
6) and adhesive resin (“Atmar QF” manufactured by Mitsui Petrochemical Co., Ltd.
500 J (maleic anhydride grafted polypropylene)) was supplied to a rough-feed block type 3-scale 5-layer coextrusion apparatus to obtain a die temperature of 230° C. and a 1 m-t. The thickness of each layer is approximately 450μ for the PP layer, 50μ for each adhesive layer (AD),
EV@H@ is approximately 507j. EVOH of this sheet
Layer thickness variation rate (thickness distribution in the direction perpendicular to the discharge) is 7%
Met. Also, I could hardly notice any streaks, bumps, or uneven flow.

The obtained sheet was molded using a vacuum pressure forming machine (F[-
0431) and 5PPP molding was performed at a sheet temperature of 150°C. (The volatile content of EVOH before molding is 0.
It was 14%. ) 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 draw-molded container was heated to 20'C-65%HLL and 20°C.
C-100% 1 (sufficient humidity control with li (about 1 month)
After that, the amount of oxygen permeation was measured using a Mocon oxygen analyzer (manufactured by NLocon). As a result, the amount of oxygen permeation through the EVO) i layer was 1.1CC-20μ/d-24hr-at
m (20℃-65%BH), 13cc・2011/i
・24 hr-atm (200C-100%BH)
It showed very good gas barrier properties.

Comparative Example 1 The same procedure as Example 1 was carried out except that vinyltrimethoxysilane was not used, and the ethylene content was 40.7 mol%.
, EVOH with a saponification degree of 99.4 mol% was obtained. Example 1
Melt film formation was performed in the same manner as in . As a result, the EVOHJ of the sheet
- The thickness variation rate exceeded 100%, and it was not only extremely unrestricted, but also had streaks and spots that were noticeable after 2 to 3 hours of film formation, making it difficult to use it over gold mines. In addition, 5PPP (solid phase air pressure forming) was performed on the part of this sheet where the thickness variation was small using a vacuum pressure forming machine, but many minute cracks were clearly observed with the naked eye on the side of the molded product, making it unusable. . The oxygen permeation rate of this container is 4000cce20cc++24hr・am(2
00C-100%BH), indicating that the EVOH layer was cut. The oxygen permeation rate of the original fabric before vacuum pressure forming is 1. o cc ・20 p/d -24hr
・ATM (20℃-65% 1it), 28CC・20
μ/ne ・24 hr 9atm (20℃-Zo
o%BH).

Comparative Example 2 In order to investigate the cause of cracks that occurred on the side of the molded product during vacuum pressure forming in Comparative Example 1, E
VOH was formed into a film using a 40φ single-layer extruder to obtain a single-layer EVOH layer with a uniform thickness (50μ film, thickness variation rate 5).
%). This EVOH film was treated with an anchor coat (Toyo Morton AT-335A) and a 1000μ polypropylene sheet (Mitsubishi Noblen MA-6) l/(after dry laminating, 8PPP molding was performed using a vacuum pressure forming machine, but the same as in Comparative Example 1) , slight cracks were observed on the side of the container. Therefore, the abnormality during deep drawing that occurred in Comparative Example 1 (
It was found that the cracks were not caused by uneven thickness, streaks, or spots in the EVOH layer during sheet preparation, but were essentially a characteristic of the EVOH used in Comparative Example 1.

Comparative Example 3 The [η)ph (measured with 15% hydrated phenol at 30°C) of EVOH used in Example 1 was 0.084 <l/Q)
, and the MI, 9G (melt index value measured at 190°C load! 2160 g) is 2.1 (9710 minutes), compared to [η
)ph = 0.081 (1/y) for M1190
= 165 (g 710 minutes). EVO) 1100 used in Comparative Example 1 because the difference in MIlgo may be considered to be the cause of abnormalities in film formability and deep drawability.
0.35 parts by weight of BPO (benzoyl peroxide) was added to each part by weight, and cross-linked pelletization was carried out using a 40φ extruder at 220°C. The obtained pellets were dried at 90° C. for 16 hours and measured by MII90t, which was 1.8 g/10 minutes.

Using this Evoul, film formation was carried out in the same manner as in Example 1. As a result, the thickness variation rate of the EV'E3J layer of the sheet was 4
Although it was 8%, lower than Comparative Example 1, it was not as high as Example 1. In addition, slight spots were observed in the 0)I EVEL layer of this sheet from the beginning of operation.
After 3 hours, streaks and flow unevenness increased, making it difficult to continue operation. Example 1
Vacuum-pressure molding was carried out in the same manner as above, but many cracks occurred on the sides of the molded product, making it unusable.

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 440g/hrt-
Butanol supply j1 60n2.
2L azobis-(2,4-dimethylchloronitrile)
110mg/hr3-acrylic gamma mitoprophylactic)
Retrimetoh+, Nsilane 150 Polymerization temperature 60℃ average residence time
8 hrs polymerization tank ethylene pressure
The polymerization rate of 46 halciG vinyl acetate was about 55%. Nuclear magnetic resonance analysis revealed that the copolymer contained 0.013 mol% of 3-acrylamide-propyltrimethoxysilane units 'i and t-65 vinyl acetate units.
It was confirmed that it contained about 35 mol% of ethylene units.

After saponification and isolation in the same manner as in Example 1, post-treatment, and drying, modified ETO)l was obtained. Saponification degree is 9
It was 9.2 mol%, and MI190 was 0.7 g/10 minutes.

I got Seatra. The thickness variation rate of this sheet was 5%, 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 passed through a biaxial stretching test device (pantograph type,
(manufactured by Toyo Seiki Co., Ltd.) and sequentially biaxially stretched 5×5 times at a sheet temperature of 150°C. The volatility of the EVOIi layer before stretching was 0.25%. 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. The oxygen permeation rate of this film is 0.5cc-20μ/d-24hr-a
tm (20℃-65%BH)20cc・20p
/lri e24 hr @ atm (20℃-10
0% BH) and 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 the ethylene content was 35 mol%, the degree of saponification was 99.3 mol%, and Ml, 90 was 2.
．． 1 g/10 min of EVOH was obtained. The EVOH layer of the sheet obtained by coextrusion film formation in the same manner as in Example 2 had a very poor thickness variation rate of 68%, and was not only non-uniform, but also had streaks and streaks after 3 to 4 hours of continuous operation. Wow, the uneven flow has become noticeable. Biaxial stretching was performed in the same manner as in Example 2 at the initial stage of operation and in a portion where the thickness variation and unevenness of the EVOEI layer were relatively small. The volatile content of the EVOH layer at this time was 0728%. This biaxially stretched film had network-like cracks over its entire surface and was completely unusable. The oxygen permeation rate of this co-stretched film is 400
0CC・20 pAre・24 hr @ atm(
20°C-100%1(H) or higher, indicating that the EVOH layer was cut. The oxygen permeation rate of the original fabric before vacuum pressure forming is 0.6 cc -20p/rri -24hr
-atm (20°C-65%EH), 35CC・20μ
The temperature was 24 hr-atm (20'C-100% RH).

Comparative Example 5 15 parts by weight of N-ethyltoluenesulfonamide was added as a plasticizer to 00 parts by weight of EVOHl used in Comparative Example 4, and pelletization was performed using a 40φ extruder at a die temperature of 220°C. . The second pellet at 95℃-16
After drying for a period of time, coextrusion film formation was performed in the same manner as in Example 2. The thickness variation rate of the obtained sheet was 21%, which shows a slight tendency to improve, but it is not enough, and to make matters worse, the sheet often shows streaks and flow irregularities 20 to 30 minutes after the start of operation, making it difficult to operate for a long period of time. was difficult. At the beginning of the operation, a portion where the temperature was - and 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 stretching, it appeared that a relatively good stretched film with no clutter was obtained, but when oxygen permeability was measured, it was found that 5 CC
War 20 p/7d-24hr ・atm (20℃-6
5%B11), 9 acc-20μ/rd-24hr-
It was found that the amount of permeation of ATM and oxygen was large, and that it was not fully satisfactory as a food packaging material with gas barrier properties. Since the crystallinity of EVOH decreases due to the addition of a plasticizer, the moldability tends to improve, but it is thought that the gas barrier properties, which are strongly related to the degree of crystallinity, deteriorate due to the decrease in crystallinity.

Example 3 In Example 2, silicon content r1”+rt 3
-acrylamide-propyltriacetoxysilane f
The same procedure as in Example 2 was carried out except that 290 rrtg/hr was used. The polymer was determined by nuclear magnetic resonance analysis to contain 3-acrylamide-propyltriacetoxysilane units 'i0
．． It was confirmed that the composition of vinyl acetate and ethylene was almost the same as that of Example 2. The degree of saponification of the modified bvon is 99.5 mol%,
MI Seki was o, 3 g/lo min. The EVOH, polystyrene (Idemitsu styrene ET-61) and adhesive resin (Toyo Soda "late 5420" (maleic anhydride grafted ethylene-vinyl acetate copolymer)) were supplied to a multi-manifold type 3-volume 5-layer co-extrusion device. , PS/AI at a die temperature of 230°C and a sheet take-up device of I B /min.
), /8i -EVOEI / A included / P8 composition sheets with a thickness of about 1 were obtained. The thickness of each layer is 4 PS layers each.
50μ, each adhesive layer was 50μ and the EVOH layer was about 50μ. The thickness variation rate (thickness distribution in the direction perpendicular to the discharge direction) of the EVOH layer of this sheet was 3%, and was 20 to 24%.
Even during long-term operation, there were hardly any streaks, bumps, or flow irregularities in the EVOH layer. The obtained sheet was subjected to drawing forming at 120° C. using a vacuum-pressure forming machine (using a pentagonal mold with drawing ratio manufactured by Asano Research Institute), and a good molded product without cracks was obtained. The oxygen permeation rate of this container is 0.
6CC・20p/71i-24hr-atm (
20°C-65%BH), 20cc ・2 o tt%
d ・24 hr -atm (20℃-65%1IH
) and showed very good gas barrier properties.

Comparative Example 6 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
I19o obtained EVOfi'ii of 1.9y/lo.

Coextrusion film formation was performed in the same manner as in Example 3. The thickness variation rate of the EVOH layer of the obtained sheet was as large as 65%, and not only was it non-uniform, but the occurrence of streaks and spots was noticeable after 3 to 4 hours of film formation. Further, when deep drawing was performed in the same manner as in Example 3 on a portion of this sheet where the thickness variation was small, many minute cracks were observed on the side surface of the molded product. The oxygen permeation rate of this container is 4000 cc・20μ/
i ・24 hr・atm (20'C-100%11
1) It was found that the EVOL (layer was cut).

Comparative Example 7 10 parts by weight of diethylene glycol was added as a plasticizer to 11 parts of EVOH 1 o N used in Comparative Example 6, and pelletization was performed using a 40φ 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%, with almost no improvement observed, and to make matters worse, uneven flow, streaks, etc. began to occur frequently after 3 to 4 hours. When a portion with a relatively uniform thickness distribution was sampled and deep drawing was performed in the same manner as in Example 3, cracks occurred, albeit slightly. The oxygen permeation rate of this container is 240 cc・20μ/d −2
It was large at 4'hr eatm (20°C - 100% B) and could not withstand use as a gas barrier container.

Example 4 In Example 2, the polymer layer ethylene pressure f 35 kg/
alG, vinyltriethoxysilane was used as the silicon-containing olefinically unsaturated monomer, and the supply amount was 100%.
The same procedure was carried out except that +ag/hr was changed.9 The obtained copolymer had vinyltriethoxysilane units of o, o o
s mol%, 72 mol% of vinyl acetate units, and about 28 mol% of ethylene units. Modified E VOfi was obtained according to Example 2. Saponification degree is 99.4 mol%
The melt viscosity index M I210 measured at 210° C., z, and isog load was 0.80 g 710 minutes.

The EVOH, polypropylene (Mitsubishi Noprene MA-6
) and adhesive resin (Ewell Petrochemical Atmer QF500)
was fed to a spiral flow type 3 type 5 layer coextrusion pipe forming machine at a die temperature of 220°C and a flow rate of 0.6 rrL/m.
PP/AD1/8i-EVOH with in-vibe collection device
/ A DI / PP Total layer thickness 3 ~ 3, outer diameter 3
011 with a 7m pipe e fr). The thickness of each layer is P
The P layer is about 1200 μm each, the AD layer is about 150 μm each, and the E layer is about 150 μm each.
The VOH layer is about 200μ. EV of the cross section of this pipe
The thickness distribution of the OH layer was as uniform as seen under a microscope (100x magnification), and no streaks, bloat, or flow irregularities in the flow direction of the pipe were visually observed (approximately 24 hours of continuous operation). This pipe was cut and the mouth and bottom were formed to create a parison, heated at 150°C for about 12 minutes, and then applied to a biaxial stretching blow machine to create a container.A good bottle with no cracks in appearance was obtained. It was done.

Comparative Example 8 The same procedure as Example 4 was carried out except that vinyltriethoxysilane was not used in Example 4, and the ethylene content was 2.
8.3 mol%, saponification degree 99.5 mol%, Ml, 902
．． 3 g/l 0 min EVOfit was obtained. Kono EVOH
The pipe was formed in the same manner as in Example 4 using
When the VOH layer was observed, several localized thickness irregularities were observed. In addition, there are streaks of EVOH layer in the flow direction of the pipe.
No uneven flow was observed. When this pipe was stretch-blow molded in the same manner as in Example 4, vertical streaks and cracks were observed on the bottle surface, and streak-like uneven thickness was observed especially in the portion (shoulder) near the mouthpiece.

Example 5 Batch polymerization was carried out under the conditions shown below in order to obtain a silicon-containing ethylene-vinyl acetate copolymer in a polymerization tank with a capacity of 50 g and equipped with an internal stirrer and a cooling filter.

Vinyl acetate charge: 15kg Methanol charge: 5.8kQ Vinyltrimethoxysila∆fi
6.4 Q2.2-7 Zobisisobutyronitrile U
≦41i 2.7 g Polymerization temperature 60℃ Polymerization tank Ethylene pressure 33kg/cJG heavy metal time
The polymerization rate of 6.5 hr vinyl acetate was 31%. It was confirmed by the magnetic resonance analysis that the copolymer contained 0.02 mol% of vinyltrimethoxysilane units, 68 mol% of vinyl acetate units, and 32 mol% of ethylene units. The product was saponified, isolated and post-treated in the same manner as in Example 1, and then dried to obtain modified hvon6. Saponification degree is 99.5%, MI, go is 0.55
j/10 minutes.

The EVOH, polypropylene (Mitsubishi Nose L/7MA-
6) and adhesive resin (Mikata Petrochemical Atmer Qf'5o
O) The product was supplied to a total spiral flow type 3 Keyaki 5 layer coextrusion blow molding machine and molded into a 50 omg bottle at a die temperature of 220°C. The structure of the bottle body is P P /
A DI / Si-E VOR / A DI /
PP, and the thickness of each layer is 300μ for each PP layer, A
The D layers are each about 20μ thick and the 8i-EVOH layers are about 20μ thick. The rate of variation in the thickness of the EVOR layer in the circumferential direction of the container (defined as (maximum thickness - minimum thickness)/percentage of average thickness) is 8.
It was 9%. In addition, no unevenness, streaks, etc. were observed in the appearance.

Comparative Example 9 The same procedure as Example 5 was carried out except that vinylmethoxysilane was not used in Example 5, and the ethylene content was 31.
8 mol%, saponification degree 99.6 mol% M11905-1
g/10 min EVOE [e obtained. This xvonf! :
When blow molding was carried out in the same manner as in Example 5, the appearance of the bottle was reasonably good, but the nv of the bottle body was
When observing the cross section of the OA layer, it was found that the thickness was highly uneven.

The thickness variation rate of the gvou layer was measured and was 85%.

When the total oxygen permeation amount of this bottle was measured, it showed a poor value of 1.8 cc/bottle.241ir-atm (0.51 bottles). The cause of this is probably that the EVOH layer is locally thin due to uneven growth and uneven thickness of the EVOE layer, which deteriorates the gas barrier properties.

Example 6 Using the same polymerization method as in Example 1, continuous polymerization was carried out under the conditions shown below.

Co-feeding amount of vinyl acetate: 400 g/hr
Methanol supply @100 g/hr Vinyltrimethoxysilane 240 ag/hr
r2.2'-7zobis-C24-dimethylbereronitrile) 17 (1rrLg/hr polymerization temperature
60℃ average residence time
5hr polymerization tank ethylene pressure
The polymerization rate of 46 kg/(11G vinyl acetate was approximately 45%. Nuclear magnetic resonance analysis revealed that the copolymer contained 0.023 mol% of vinyltrimethoxysilane units, 61 mol% of vinyl acetate units, and 61 mol% of vinyl acetate units. It was confirmed that it contained about 39 mol% of units.

After saponification, isolation, post-treatment in the same manner as in Example 1, and drying, modified EVOH was obtained. Saponification degree is 99.
It was 4 mol % and -MI,90 was 1.3 g 710 minutes.

The EVOR and polypropylene (Mitsubishi Noblen MA-
6) is fed to a two-layer three-layer co-injection molding machine to form a multilayer bar! J So 7
All created by Shita. PP/8i-EVOH/PP The thickness of each layer of the PP component is 1200μ each, and the EVOE
The I layer was 200μ. 5i-E of the cross section of this vibe
The thickness distribution of the VOE layer was uniform as seen under a microscope (x100). This parison was heated at 150'C for about 15 minutes and subjected to a Nissin A8B biaxial stretch blow molding machine to prepare a container, and a good bottle with no cracks in appearance was obtained.

Comparative Example 10 Example 6 The same procedure as Example 6 was carried out except that vinyltrimethoxysilane was not used, and the ethylene content was 39 mol%, the degree of saponification was 99.4 mol%, and the MI was 901.
5 g/I o min of EVOHf was obtained. ,:EVOE1
2 was used to create a parison in the same manner as in Example 6, and stretch blow molding was performed. Vertical streaks and cracks were observed on the bottle surface, and streak-like uneven thickness was observed particularly in the area near the mouth (shoulder). , could not withstand use.

Claims (2)

[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 multilayer structure having a polypropylene resin or polystyrene 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% ▲Math. There are , 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 0-2, 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 has an oxygen-containing substituent. may have. 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 multilayer structure according to claim 1, wherein the multilayer structure is a heat-stretched multilayer structure.