JPH0377774B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Technical Field of the Invention The present invention relates to a coextruded laminate having excellent gas barrier properties and good adhesive strength between resin layers. More specifically, a saponified ethylene-vinyl acetate copolymer resin layer (A) and a polycarbonate (B) are bonded together through an adhesive resin layer (C) containing an ethylene-acrylic acid ester copolymer that satisfies specific conditions. The present invention relates to a method for producing a laminated body and a laminated body obtained by coextruding the laminated body.

B. Conventional technology and its problems Technological innovation in the food packaging industry in recent years has been remarkable.
For example, it is well known that thermoplastic resins such as polycarbonate are being used for food packaging for the purpose of sanitary properties, beautiful appearance, and weight reduction to reduce transportation costs. However, these polycarbonate resins have poor barrier properties against oxygen and carbon dioxide, making them unsuitable for long-term storage of foods, carbonated drinks, etc. Glass bottles and metal cans are often used, and empty cans are not stored on the street. There are many problems such as the pollution caused by throwing bottles and the cost required to collect them, and the development of alternative packaging materials has been delayed.

Saponified ethylene-vinyl acetate copolymer resin with an ethylene content of 20 to 55 mol% has melt moldability.
As a material with high transparency and excellent gas barrier properties, it has excellent properties as a food container and packaging material. However, it has drawbacks in other physical properties, such as rigidity and moisture resistance, and is not fully satisfactory.

On the other hand, polycarbonate, especially polycarbonate obtained from 4,4' dihydroxydiphenyl-2,2-propane, has excellent moldability, balance between impact resistance and rigidity, hygiene, and heat resistance, but it It has limited gas barrier properties against carbon dioxide gas and cannot store foods and drinks for long periods of time, so its use as food containers and packaging materials is limited.

Therefore, in order to obtain food containers and packaging materials that have good gas barrier properties of saponified ethylene-vinyl acetate copolymer and excellent mechanical properties of polycarbonate resin, we thought of laminating layers of both resins. It will be done. However, these two resin layers have almost no affinity with each other, and it is impossible to obtain a laminate by mere thermal bonding.
Furthermore, it is not sufficient for the adhesive resin used in coextrusion molding to simply have adhesive properties; it must satisfy various molding properties such as heat resistance and melt viscosity.

In view of these circumstances, the present inventors have considered the necessary characteristics of an adhesive resin coextruded with a saponified ethylene-vinyl acetate copolymer and a polycarbonate resin, and as a result of intensive study, the present invention has been arrived at. .

C Structure, purpose, and effects of the present invention That is, the present invention provides adhesive resin (C) containing a copolymer consisting of an ethylene component, an acrylic ester component, and an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride component. , ethylene component content 20-55
This is a laminate in which a saponified ethylene-vinyl acetate copolymer (A) with a saponification degree of 90 mol% or more and a polycarbonate (B) are laminated.

The object of the present invention is to have good interlayer adhesion, combine the excellent mechanical properties of polycarbonate resin with the excellent gas barrier properties of saponified ethylene-vinyl acetate copolymer resin, and The objective is to industrially obtain a laminate that is excellent as a container or packaging material.

The most important feature of the present invention is that a copolymer consisting of an ethylene component, an acrylic ester component, and an ethylenically unsaturated carboxylic acid or carboxylic acid anhydride component is used as the adhesive resin for the layer (C).

JP-A No. 54-101883 describes the chemical method of adding ethylenically unsaturated fatty acids or their anhydrides to a copolymer of ethylene and a monomer containing a carboxyl group or a substituent group thereof, using a thermoplastic resin and a saponified ethylene-vinyl acetate copolymer. This shows that a modified copolymer obtained by bonding can be laminated as an intermediate layer.

However, when a copolymer consisting of an ethylene component, an acrylic ester component, and an ethylenically unsaturated carboxylic acid or carboxylic acid anhydride component is used as the adhesive resin for a laminate made of a combination of various resins, (A ), depending on the combination of (B) layer resins, it may adhere strongly to the (A) layer resin but not at all to the (B) layer resin, or conversely, the (B) layer resin may have no adhesion. However, it often does not adhere to the (A) layer resin. For example, Admar NF.500 (trademark, Mitsui Seki Kagaku), which is effective as an adhesive resin coextruded with polyolefin and saponified ethylene-vinyl acetate copolymer and is used industrially, does not adhere to polycarbonate at all. Therefore, the quality of the adhesive resin layer is determined individually depending on the combination of adherend layers. In view of such cases in place of coextrusion bonding, and from the descriptions in the above-mentioned publications, it is hard to imagine the remarkable effects of the present invention.

D More detailed description of the present invention The acrylic ester component of the copolymer consisting of an ethylene component, an acrylic ester component, and an ethylenically unsaturated carboxylic acid or carboxylic acid anhydride component used in the present invention is 10 to 30% by weight. range. If the content of this component is less than 10% by weight, the adhesion to polycarbonate will not be sufficient, and the object of the present invention will not be met. Moreover, if it is used in an amount exceeding 30% by weight, the resin becomes too soft and problems such as wavy patterns appearing on the molded product and non-uniform thickness of each layer tend to occur, so this is not recommended. The content of carboxyl groups in the ethylenically unsaturated carboxylic acid or carboxylic acid anhydride component is 0.01 to 1.5 meq/g. If it is less than 0.01 meq/g, the adhesion not only to polycarbonate but also to saponified ethylene-vinyl acetate copolymers will decrease, so this is not recommended. Even if it is introduced in an amount exceeding 1.5 meq/g, the effects such as adhesiveness will not only be saturated, but also cause discoloration, strange odor, lumps, etc., so this is not recommended.

In the present invention, acrylic esters are esters of lower aliphatic (1 to 8 carbon atoms) alcohols of acrylic acid, such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Among these, ethyl acrylate is preferred.

There are no particular restrictions on the method for producing a copolymer consisting of an ethylene component, an acrylic ester component, and an ethylenically unsaturated carboxylic acid or the carboxylic anhydride component. Graft polymerization with an ethylenically unsaturated carboxylic acid such as itaconic acid or maleic anhydride or the carboxylic acid anhydride, saponification of the acrylic ester component of an ethylene acrylic ester copolymer, or ethylene, acrylic acid There are methods such as ternary copolymerization of an ester and an ethylenically unsaturated carboxylic acid such as acrylic acid or methacrylic acid, or an anhydride of the carboxylic acid, but it is also possible to graft maleic anhydride onto an ethylene-acrylic acid ethyl ester copolymer. Alternatively, it is particularly preferable to co-graft styrene and maleic anhydride.

It is more preferable that the adhesive resin used in the present invention satisfies the following formula () at a temperature between 0° C. and 70° C. from the viewpoint of adhesion during high-speed molding of the laminate.

logE′≦9.48−0.0176T…() [E′: Real part of complex modulus measured at 110Hz (dyne/cm ² ) T: Temperature (°C)] Although the reason is not clear, the ethylene-vinyl acetate It is thought that the value of the real part of the complex modulus between the temperature near or below the second-order transition point of the saponified copolymer and the cooling temperature is particularly affected by high-speed molding. When the real part of the complex modulus of elasticity is smaller than the range of formula (), the stress applied between the layers after extrusion until cooling is sufficiently relaxed, and the adhesive force cannot be fully exerted, especially during high-speed molding. I think so.

More preferably, the adhesive resin used in the present invention is a copolymer consisting of an ethylene component, an acrylic ester component, and an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride component so as to satisfy the following formulas () to (). This is an adhesive resin composition containing a copolymer (X) and a copolymer (Y) consisting of an ethylene component and an acrylic acid ester component.

｜Vx−Vy｜≦0.15 …() 0.10≦｜Vx・Wx＋Vy・Wy｜≦0.30
…() 0.01≦Cx・Wx≦1.5 …() 0.01≦Wx／(Wx＋Wy)≦0.7 …() However, Vx: acrylic ester component content (weight fraction) of copolymer (X) Vy: copolymer Acrylic acid ester component content (weight fraction) of the copolymer (Y) Cx; Carboxyl group content (meq/g) due to ethylenically unsaturated carboxylic acid or carboxylic acid anhydride properties of the copolymer (X) Wx; Amount of copolymer (X) (weight fraction) Wy: Amount of copolymer (Y) (weight fraction) Although the reason is not necessarily clear, ethylenically unsaturated carboxylic acid or the carboxylic acid component X and Y due to the presence or absence of
A complex difference occurs in the mutual affinity between the polycarbonate resin and the ethylene-vinyl acetate copolymer, and micro phase separation occurs in the adhesive resin when the two are blended or coextruded. It is thought that it has a moderate affinity with the saponified resin and exhibits good adhesion and moldability with both.

Next, in the present invention, the resin used as layer (A) is a saponified ethylene-vinyl acetate copolymer having an ethylene component content of 20 to 55 mol% and a saponification degree of 90 mol% or more. When the content of the ethylene component is less than 20 mol%, melt molding of the obtained saponified resin is difficult;
If it exceeds 55 mol%, gas barrier properties tend to deteriorate, which is not preferable. The degree of saponification of the vinyl acetate component is 90 mol% or more. If it is less than 90 mol%, not only will gas barrier properties be low, but heat resistance and
Physical properties such as water resistance also tend to deteriorate, which is undesirable.

The polycarbonate used as layer (B) has a carbonic acid component and a diol component linearly bonded via ester bonds within the molecule. Diol components include 4,4'-dihydroxydiphenyl-1,1-ethane, 4,4'-dihydroxydiphenyl-2,2
-propane, 4,4' dihydroxydiphenyl sulfone, etc. are used. These can be produced by known methods such as transesterification of carbonate esters such as diphenyl carbonate with or without the use of a catalyst and then under reduced pressure, or reaction with phosgene in the presence of an acid binder. can get.

The laminate of the present invention uses the resin described above, and T
Obtained by known methods such as extrusion molding, injection molding, and blow molding using a die, ring die, etc.
Further, secondary forming using vacuum or compressed air may also be performed. In this case, the polycarbonate layer (B) may be the inner layer or the outer layer. Also, as laminates, (A)-(C)-(B), (B)-(C)-(A)-(C)-(B), (A
)−
It can have a multilayer structure such as (C)-(B)-(C)-(A). Furthermore, the polycarbonate layer (B) can also have a multilayer structure if necessary. Further, other resin layers (for example, polyolefin layers such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc.) may also be laminated on the laminate of the present invention thus obtained. can.

There is no particular restriction on the thickness of each layer of the laminate obtained in this way, but the thickness of layer (A) is 10 to 400μ, and the thickness of layer (C) is 5 to 400μ.
300μ, and (B) layer preferably has a thickness in the range of 50 to 3000μ.

In addition, the resulting laminate has sufficient adhesion between each layer, and has both the excellent mechanical properties of polycarbonate resin and the excellent barrier performance of saponified ethylene-vinyl acetate copolymer, and is suitable for use in food containers. (cups, etc.) are truly useful as packaging materials.

The present invention will be demonstrated below with reference to Examples, but the present invention is not limited thereto.

Example 1 Toluene purified from 150 parts by weight of ethylene-ethyl acrylate copolymer containing 26% by weight of ethyl acrylate component and 12 parts by weight of maleic anhydride
It was dissolved in 1000 parts by weight and kept at 150°C. A solution of 1.2 parts by weight of benzoyl peroxide dissolved in 50 parts by weight of xylene was added to this solution at 150°C with stirring.
The mixture was added dropwise over a period of time, followed by continued stirring for 20 minutes. After cooling, the reaction solution was poured into a large amount of purified acetone to precipitate a polymer. The obtained polymer was purified by reprecipitation using purified xylene as a solvent and purified acetone as a non-solvent. This product contained 25.9% by weight of ethyl acrylate component and 0.88 meq/g of carboxyl groups. MI (190℃,
2160g) was 8g/10 minutes.

Ethylene component thus obtained - Ethyl acrylate component - Ethylene component containing 20% by weight of copolymer X consisting of ethylenically unsaturated carboxylic anhydride component and ethyl acrylate component and having an MI of 5 -
A copolymer Y consisting of an ethyl acrylate component was blended in a ratio of X/Y = 30/70. The temperature distribution of the real part of the complex modulus of this composition is shown in curve 1 of FIG. Also, |Vx−Vy|=0.059 Vx・Wx+Vy・Wy=0.218 Cx・Wx=0.264 Wx/Wy=0.429, which satisfied formulas () to ().

This adhesive resin composition is used as the (C) layer resin, and the content of the vinyl acetate component is 99.6 mol% of the vinyl acetate component of the ethylene-vinyl acetate copolymer with a content of 67 mol%.
The saponified ethylene-vinyl acetate copolymer resin with [η] = 1.11 (phenol/water = 85/15 mixed solution, 30°C, dl/g) obtained by saponifying the (A) layer resin A laminate was obtained using polycarbonate {"Corpilon E-2000" (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd.} as the (B) layer resin by the following method.

Equipped with an extruder with an inner diameter of 120 mmφ, an extruder with an inner diameter of 60 mmφ, and an extruder with an inner diameter of 90 mmφ. In the case of the extruder, the molten material is separated into two layers each, and then the resin layer melted and extruded from the extruder is transferred to the extruder. A multi-manifold three-layer, five-layer coextrusion device is used in which the resin from the extruder is sequentially merged with the resin from the extruder. The (A) layer resin is supplied to the machine, and coextrusion is carried out at a die temperature of 280°C and a withdrawal speed of 7 m/min. A laminate with good appearance of the layers was obtained. The thickness of each layer is (A)
The peel strength between (A) and (B) (T peel, 200 mm/min) was good at 1.9 Kg/cm.

Example 2 Xylene purified from 100 parts by weight of ethylene-ethyl acrylate copolymer containing 25% by weight of ethyl acrylate component and 20 parts by weight of maleic anhydride
It was dissolved in 1000 parts by weight and kept at 160°C. A solution of 0.8 parts by weight of benzoyl peroxide dissolved in 100 parts by weight of xylene was added to this solution at 140°C for 30 minutes with stirring.
The mixture was added dropwise over a period of time, followed by continued stirring for 20 minutes. After cooling, the reaction solution was poured into a large amount of purified acetone to precipitate a polymer. The obtained polymer was purified by reprecipitation using purified xylene as a solvent and purified acetone as a non-solvent. This product contained 24.2% by weight of ethyl acrylate component and 0.61 meq/g of carboxyl groups. MI (190℃,
2160g) was 3.2g/10 minutes.

Ethylene component thus obtained - Ethyl acrylate component - Ethylene component containing 25% by weight of copolymer X consisting of ethylenically unsaturated carboxylic acid anhydride component and ethyl acrylate component and having an MI of 5 -
A copolymer Y consisting of an ethyl acrylate component was blended in a ratio of X/Y = 50/50. The temperature distribution of the real part of the complex modulus of this composition is shown in curve 2 of FIG. Also, |Vx−Vy|=0.008 Vx・Wx+Vy・Wy=0.246 Cx・Wx=0.305 Wx/Wy=1.0, which satisfied formulas () to ().

This adhesive resin composition is used as the (C) layer resin, and the content of the vinyl acetate component is 99.5 mol% of the vinyl acetate component of the ethylene-vinyl acetate copolymer with a content of 56 mol%.
A saponified ethylene-vinyl acetate copolymer resin with [η] = 0.96 (phenol/water = 85/15 mixture, 30°C, dl/g) obtained by saponifying is used as the (A) layer resin. .

A laminate was obtained in the following manner using polycarbonate {“NOVAREX7030A” (trade name) manufactured by Mitsubishi Chemical Industries, Ltd.} as the (B) layer resin.

Feedblock type three-layer, three-layer type, equipped with three extruders: an extruder with an inner diameter of 95 mmφ, an extruder with an inner diameter of 60 mmφ, and an extruder with an inner diameter of 110 mmφ, and the resin from the extruders merges sequentially to form the center layer. Using a co-extrusion device, supply the (A) layer resin to the extruder, the (C) layer resin to the extruder, and the (B) layer resin to the extruder, with a die temperature of 280°C and a take-up speed of 7 m. Coextrusion was carried out at a speed of 1/min to obtain a clean laminate with a three-layer structure of (A)/(C)/(B). The thickness of each layer is 70μ for (A) layer, 150μ for layer (B), and 20μ for layer (C), and the peel strength between (A) and (B) is
It was good at 1.9Kg/cm.

Comparative Example 1 Xylene purified from 100 parts by weight of ethylene-ethyl acrylate copolymer containing 7% by weight of ethyl acrylate component and 20 parts by weight of maleic anhydride.
It was dissolved in 1000 parts by weight and kept at 140°C. A solution of 0.8 parts by weight of benzoyl peroxide dissolved in 100 parts by weight of xylene was added to this solution at 140°C for 30 minutes with stirring.
The mixture was added dropwise over a period of time, followed by continued stirring for 20 minutes. After cooling, the reaction solution was poured into a large amount of purified acetone to precipitate a polymer. The obtained polymer was purified by reprecipitation using purified xylene as a solvent and purified acetone as a non-solvent. This product contained 6.8% by weight of ethyl acrylate component and 0.663meq/g of carboxyl group (190℃, 2160℃).
g) was 2.2 g/10 minutes.

A laminate obtained in the same manner as in Example 1 except that the thus obtained copolymer consisting of an ethylene component, an ethyl acrylate component, and an ethylenically unsaturated carboxylic anhydride component was used as the (C) layer resin. Although the appearance was almost good, the peel strength was only 0.2 kg/cm, which was insufficient. The (A) layer was 65μ, the (B) layer was 160μ, and the (C) layer was 20μ.

Comparative Example 2 Xylene purified from 100 parts by weight of ethylene-ethyl acrylate copolymer containing 25% by weight of ethyl acrylate component and 2 parts by weight of maleic anhydride.
It was dissolved in 1000 parts by weight and kept at 120°C. A solution of 0.2 parts by weight of benzoyl peroxide dissolved in 100 parts by weight of xylene was added to this solution at 120°C with stirring.
The mixture was added dropwise over a period of time, followed by continued stirring for 20 minutes. After cooling, the reaction solution was poured into a large amount of purified acetone to precipitate a polymer. The obtained polymer was purified by reprecipitation using purified xylene as a solvent and purified acetone as a non-solvent. This product contained 24.9% by weight of ethyl acrylate component and 0.005 meq/g of carboxyl groups. MI (190℃,
2160g) at 4.5°C/10 minutes.

A laminate obtained in the same manner as in Example 2 except that the thus obtained copolymer consisting of an ethylene component, an ethyl acrylate component, and an ethylenically unsaturated carboxylic anhydride component was used as the (C) layer resin. Although the appearance was almost good, the peel strength was only 0.1 kg/cm, which was insufficient. The (A) layer was 70μ, the (B) layer was 150μ, and the (C) layer was 25μ.

Comparative Example 3 Toluene purified from 100 parts by weight of ethylene-ethyl acrylate copolymer with an ethyl acrylate component content of 40% by weight and 8 parts by weight of maleic anhydride
It was dissolved in 1000 parts by weight and kept at 170°C. A solution of 0.8 parts by weight of benzoyl peroxide dissolved in 100 parts by weight of toluene was added to this solution at 170°C with stirring.
The mixture was added dropwise over a period of time, followed by continued stirring for 20 minutes. After cooling, the reaction solution was poured into a large amount of purified acetone to precipitate a polymer. The obtained polymer was purified by reprecipitation using purified toluene as a solvent and purified acetone as a non-solvent. This product contained 37.1% by weight of ethyl acrylate component and 1.46 meq/g of carboxyl groups. MI (190℃,
2160g) 6g/10 minutes.

An attempt was made to create a laminate in the same manner as in Example 1, except that the (C) layer resin was made of this polymer consisting of an ethylene component, an ethyl acrylate component, and an ethylenically unsaturated carboxylic anhydride component. The appearance of the obtained product was wavy and had bumps in various places, and was of low commercial value.

[Brief explanation of drawings]

Figure 1 shows the real part of the complex modulus of various adhesive resins.
This is a graph showing the relationship between E′ and temperature T, and the vertical axis is
logE', the horizontal axis indicates the temperature T (°C). 1...Curve of Example 1, 2...Curve of Example 2.

Claims (1)

[Claims] 1. Carboxyl group content of 0.01 due to ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride component
~1.5meq/g, acrylic acid ester component: 10~
Through an adhesive resin (C) containing a copolymer consisting of an ethylene component containing 30% by weight, an acrylic acid ester component, and an ethylenically unsaturated carboxylic acid or carboxylic acid anhydride component, the ethylene component content is 20 to 55%.
A laminate comprising saponified ethylene-vinyl acetate copolymer (A) and polycarbonate (B) having a saponification degree of 90 mol% or more by mol%. 2. The laminate according to claim 1, wherein the adhesive resin satisfies the following formula () at a temperature of 0°C to 70°C. logE′≦9.48−0.0176T…() [E′: Real part of complex modulus measured at 110Hz (dyne/cm ² ) T: Temperature (°C)] 3 Adhesive resin is ethylene component − acrylic ester component − A copolymer (X) consisting of an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride component and a copolymer (Y) consisting of an ethylene component and an acrylic acid ester component in a manner that satisfies the following formulas () to (). Claim 1 which is a blended composition
Or the laminate according to item 2. ｜Vx−Vy｜≦0.15 …() 0.10≦｜Vx・Wx＋Vy・Wy｜≦0.30
…() 0.01≦Cx・Wx≦1.5 …() 0.01≦Wx／(Wx＋Wy)≦0.7 …() However, Vx: acrylic ester component content (weight fraction) of copolymer (X) Vy: copolymer Acrylic acid ester component content (weight fraction) of the copolymer (Y) Cx; Carboxyl group content due to the ethylenically unsaturated carboxylic acid or carboxylic acid anhydride component of the copolymer (X) (meq/g) Wx; Amount of copolymer (X) (weight fraction) Wy: Amount of copolymer (Y) (weight fraction)