JPS6244446A - Permeability-resistant laminate - 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. Field of Industrial Application The present invention relates to a laminate which has outstanding moldability, especially stretchability, and excellent gas permeation resistance f'.

B. Since the conventional technology, ethylene-vinyl alcohol co-acid (hereinafter E
VOH) is widely known as a melt-formable thermoplastic resin with excellent gas permeability, oil resistance, solvent resistance, etc., and is used as a packaging film in the field of single-layer packaging, especially for food packaging. , sheets, containers, etc.

However, compared to thermoplastic resins such as polyolefins, EVOH resins are difficult to melt mold and are particularly poor in stretch formability. Cracks and uneven stretching occur during plastic processing such as drawing, pressure forming, plug-in forming, and stretch blow forming. It has the disadvantage that it is thin, and the transparency of Ti molded products tends to be uneven.

In recent years, as requirements for the performance of various packaging containers have become more sophisticated, they are increasingly used in combination with other resins, such as polyolefins such as polyethylene and polypropylene, and polystyrene. It is used as an intermediate layer of a multilayer sheet laminated with resin and is formed by solid phase pressure forming, for example, with a drawing ratio of 0.5 to 3.
It has become mainstream to form the cup into a cup to improve the physical properties. However, the melt moldability and stretch moldability of EVO)i, which has an ethylene content of 25 to 40 mol, particularly in the range of 25 to 40 mol, which has excellent gas permeation resistance, are not satisfactory as described above. However, in fields where similar properties are required, it is necessary to sacrifice gas permeation resistance and use EVOf (with an ethylene content of more than 40 moles, especially more than 45 moles). It is.

The actual situation is the same when the h:VOH film alone or laminated with another thermoplastic resin is subjected to stretching processing in the form of a hole. In other words, the actual situation is that when biaxially stretching a single film in the ethylene-containing region, for example, a satisfactory biaxially stretched film cannot be obtained unless moisture is added through some kind of humidity conditioning or hydration operation ( fC and the like are JP-A-50-14476, 1% JP-A-52-15570, JP-A-53-30670, etc.].

tfc Laminated film having the EVOH as an intermediate layer, the EV
A film in which an OH layer is laminated on one side of a thermoplastic film is stretched in a substantially water-free state, especially,
Biaxial stretching has the disadvantage that cracks and stretching unevenness are likely to occur in the EVOH layer, as in the drawing process and stretch blow molding.

On the other hand, as a method to improve the melt moldability of EVOR, a resin composition obtained by melting and kneading different EVOs in a specific ethylene content range and having a constant composition is used for molding films, sheets, and containers. (Tokuko Sho 58-20
No. 976), and blends of EVOH and nylon have been proposed (for example, 1% open 1@58-1290).
35, JP-A-58-154755, etc.).

However, although the former method shows some improvement in melt moldability, it has drawbacks such as insufficient transparency of the molded product. In addition, in the latter case, EVOR's high gas permeability resistance is not only impaired due to blending with nylon, which has poor gas permeation resistance, but also the thermal stability is poor, especially during thermal operations during melt molding. This method has not been put into practical use satisfactorily due to the generation of a gel-like substance, which is thought to be caused by the reaction.

In addition, it was used as a food packaging material with excellent moldability.
No. 8125, etc., α-
EVOH resins modified with olefins have been proposed. However, although these resins show some improvement in moldability and transparency of molded products, their gas permeability resistance is insufficient and they have not been put into practical use.

C1 Problems to be Solved by the Invention The present invention does not have the above-mentioned drawbacks, that is, it has excellent stretchability with a moldability of 1%, the transparency of the molded product is significantly high, and it has beautiful gas permeation resistance without cracks or uneven stretching. The purpose of this invention is to provide a laminate with high quality.

As a result of extensive research, the present inventors found that a layer of a saponified ternary compound containing specific amounts of each of acrylonitrile units, ethylene units, and vinyl acetate units and a layer of other thermoplastic resins. A laminate including at least double of the conventional EV
The moldability is significantly improved compared to laminates using OH resin, and the transparency is high.

They found that it is extremely beautiful, has high gas permeation resistance, and is outstandingly excellent as a material for food packaging, etc., leading to the completion of the present invention.゛E8 Effects According to the present invention, a saponified ternary co-alcoholic compound containing specific amounts of each of acrylonitrile units, ethylene units and vinyl acetate units is coextruded with other thermoplastic resins, for example, to form a multilayer structure. When a sheet or pipe, etc. is shaped into a bottom shape, and then the laminated sheet is deep-drawn using a solid phase pressure forming method, or when the laminated pipe is blow-molded, it has extremely good stretchability without causing cracks or uneven stretching. It has the feature of being In addition, it has excellent gas permeation resistance, fragrance retention, oil resistance, and mechanical properties comparable to laminates using conventional EVOH resin, so it is used as a film in various packaging fields, especially in the food packaging field. sheet,
It is suitably used in the form of a container or the like.

F. More Detailed Description of the Invention The laminate having excellent gas permeation resistance of the present invention contains -i 0.1 to 3 mol% of acrylonitrile units, -3122 to 55 mol% of ethylene units, and the remainder is acetic acid. From a laminate comprising at least two layers: a layer of a copolymer with a vinyl acetate component having a saponification degree of 98 mol or more obtained by saponifying a terpolymer consisting of vinyl units, and a layer of another thermoplastic resin. The content of 0 acrylonitrile units is 0.
It is important that the amount is in the range of 1 to 3 moles, and a more preferred range is 0.5 to 2 moles. If the content of acrylonitrile units is less than 0.1 mole, the moldability, inter alia,
Since the stretchability is not improved, a highly transparent and beautiful molded product without cracks or uneven stretching cannot be obtained, and on the other hand, if the thickness is greater than 3 mulch, the thermal stability will be poor.

It is undesirable because it tends to gel during melt molding, and its water resistance and humidity resistance are reduced, as well as gas permeation resistance at high humidity.

It is important that the content of ethylene units is in the range of 20 to 55 moles, and a more preferred range is 25 to 50 moles. If the implication of the ethylene unit is 20 mol% smaller,
Water resistance/moisture resistance decreases, and gas permeability resistance at high humidity is impaired; on the other hand, if it is thicker than 55 mulch, water resistance/moisture resistance improves, but gas permeability resistance at low humidity deteriorates. All of them are unsuitable for packaging, especially for food packaging.

Saponification of vinyl acetate component [Vi] It is necessary to have a high saponification degree of 98 molt or more, more preferably 99 molt or more. If the degree of saponification is less than 98 molt, thermal stability deteriorates, gelation tends to occur during melt molding, and gas permeation resistance also becomes poor, which is not preferable.

The intrinsic viscosity of the copolymer, that is, the intrinsic viscosity 1" measured at a temperature of 30°C in a mixed solvent of 85% by weight of phenol and 15% by weight of water, is not particularly limited, but is 0.07 to 0.
．． It is preferably in the range of 171/f.

In general, the intrinsic viscosity is 0.071/? If υ is too small, the mechanical properties of the molded product will be poor; on the other hand, 0.171/? If it is thicker, gelation is more likely to occur during melt molding.

Either case is not preferable.

A saponified product of a terpolymer consisting of acrylonitrile units, ethylene units and vinyl acetate units can be produced industrially by conventionally known methods. Namely.

5 Acrylonitrile, ethylene and hynyl acetate in the presence or absence of alcohol such as methanol
Copolymerization is carried out using a known radical polymerization initiator such as α'-azobinuisopteronitrile.

The resulting copolymer is then saponified in an alcohol solution using an alkali catalyst such as sodium hydroxide.

Thermoplastic resins used for lamination with the copolymer include polypropylene and polyethylene.

Preferred are ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, thermoplastic polyester such as polyethylene terephthalate, polyamide resin such as 6-nylon and 6.6-nylon, polystyrene, polyvinyl chloride, polycarbonate, and the like.

Among these, particularly preferred are polypropylene,
Polyenalene, ethylene-propylene copolymer, thermoplastic polyester, and polystyrene.

, the laminate of the present invention has acrylonitrile units as described above,
It is a laminate including at least two layers, a layer of a copolymer obtained by saponifying a terpolymer consisting of ethylene units and vinyl acetate units, and a layer of the other thermoplastic resin described above, and its composition is The copolymer/thermoplastic resin, thermoplastic resin/copolymer/thermoplastic resin, thermoplastic resin/copolymer/thermoplastic resin/copolymer/thermoplastic resin, etc. The plastic resin may be a single layer.

In some cases, it may be multi-layered.

The laminate can be formed by known methods such as extrusion molding and injection molding. For example, in the case of extrusion molding, an extruder for saponified terpolymers consisting of acrylonitrile units, ethylene units, and vinyl acetate units and an extruder for other thermoplastic resins are used to place these resin layers in adjacent positions. In this case, a method of co-extrusion through a T-die for multiple layers or an inflation die is adopted. Further, the laminate can also be formed by lamination techniques such as extrusion lamination, coating techniques, and the like.

The laminate thus formed has extremely good stretch formability compared to a laminate using conventional EVOH resin,
For example, when deep drawing or stretch blow molding is carried out, the copolymer layer in the above structure does not cause cracks or uneven stretching, and has a significantly high transparency.

A molded product with excellent gas permeation resistance can be obtained.

The laminate (film, sheet, pipe, parison) is a laminate film stretched at least uniaxially.

It can be used as a material for deep-drawn containers, stretch-blown containers, etc., but it is particularly effective as a material for deep-drawn containers, especially deep-drawn containers with a drawing ratio of 0.5 or more, and even more so with a drawing ratio of 0.8 to 3. show. A deep-drawn container, for example a cup-shaped container, is obtained by subjecting a sheet made of the laminate to drawing, air pressure forming, vacuum forming, plug assist forming, etc. at a stretching temperature. Further, a stretched blow bottle is obtained by mechanically stretching a preform such as a parison made of the laminate at a stretching temperature and blow stretching it in the circumferential direction by blowing fluid.

In the present invention, the thickness of the copolymer layer in the laminate varies depending on the required performance of the resulting deep-drawn container, stretched blow bottle, etc., but is preferably 2 to 40 microns. In addition, when obtaining a laminate using the copolymer, each layer is preferably arranged through an adhesive resin, and the adhesive resin is not particularly limited, but polyethylene, ethylene-vinyl acetate copolymer Polypropylene, carboxyl group-modified products such as ethylene-acrylic acid ester copolymers, and especially maleic anhydride-modified products are preferably used as they are or by being packed with the unmodified polymer.

Next, the present invention will be explained in more detail with reference to Examples.
These examples do not limit the invention in any way.

Example 1 Content of acrylonitrile units: 0.9 mol.
A 5.3 mol-acrylonitrile-ethylene-vinyl acetate copolymer was saponified in methanol using sodium hydroxide as a catalyst to obtain a saponified product (copolymer A) with a saponification degree of 99.6 mol of the vinyl acetate component. . 3 of the copolymer in a mixed solvent of 85% by weight of phenol and 15% by weight of water.
The intrinsic viscosity (hereinafter referred to as ηlph) measured at a temperature of 0°C is 0.105 I/l, and the melt index (
190℃, load 216(1) is 2.5f/10min, s
*.

Using this copolymer, a laminate of 3 types and 5 layers was obtained by the following method. In other words, the extruder for the inner and outer layers is equipped with a built-in full-flight screw with a diameter of 65 fi and an effective length of 1430 mm, and a melt channel that branches into two flow paths, and a full-flight screw with a diameter of 50 fin and an effective length of 1100 mIn. An extruder for the intermediate layer and a diameter of 401. effective length 8
Using a combination of adhesive layer extruder equipped with a built-in 80-long full-flight screw and a melt channel branched into two flow paths, and a 15-layer T-die, a width of 200 mm and a thickness of 1.
．． A 1-inch laminated sheet was obtained. The resin used for molding was the copolymer A mentioned above for the middle layer, and the melt index 1. for the inner and outer layers.
4 f/10 min (230°C, load 2160 f) polypropylene (Mitsubishi Yuka, trade name Mitsubishi Noblen MA-5),
In addition, the adhesive layer has a melt index of 3 and an El/lo content (
230'C, load 216(1)O Polypropylene modified with maleic anhydride (Mitsui Petrochemical, trade name Atomer QF500).

The molding temperature is 180-225°C in the extruder for the intermediate layer.

Extruder for inner and outer layers: 200-240' C1 Extruder for adhesive layer: 160-240°C% T-die: 240°C. Next, the laminated sheet was subjected to solid phase air forming to bring the sheet surface temperature to 1.
Under conditions of 45°C, a cylindrical cup with an inner diameter (J) of 100 mm + depth L) of 200 fl (drawing ratio L/D = 2), a wall thickness of 0.5 m, and an internal volume of X and St was obtained. Ta.

The thickness ratio of outer layer:adhesive layer:intermediate layer:adhesive layer:inner layer is 45
:2.5:5:2.5:45.

The properties of the cup are shown in Table 1.

In addition, as a control example, the content of ethylene unit! 34.2 mol %, content of vinyl acetate units 65.8 mol - Saponification of vinyl acetate component obtained by saponifying ethylene-vinyl acetate copolymer 1i99.5 mol, [η] phO, 110 A/
? , melt index (190℃, load 216 (1
When a cylindrical cup was molded in the same manner as in Example 1 except that EVOH (copolymer B) of 2.2 r/10 min was used in the intermediate layer (Control Example 1), the content of propylene units was 1 The degree of saponification of the vinyl acetate component obtained by saponifying a propylene-ethylene-vinyl acetate copolymer with a content of .2 moles and ethylene units (fi of 34.1 moles and a vinyl acetate content of !64.7 moles) is 99.3 moles. Attack, [η:]ph O, 10
51/? , melt index (190℃, load 21
60? )3. When a cylindrical cup was molded in the same manner as in Example 1 except that EVOH (copolymer C) modified with propylene with OS'710 was used (Control Example 2), the content of ethylene units was 31.0 mol. Contains vinyl acetate units! Saponified vinyl acetate component obtained by saponifying a 69.0 mol ethylene-vinyl acetate copolymer: 1i99.3 mol, [η] ph 0.1181/l, melt index 1.2 f/10 min (190°C, Load 216C1)
Contains 60 parts by weight of EVOH and ethylene units of 1140.4
It was obtained by saponifying an ethylene-hinyl acetate covalent polymer containing 59.6 moles of vinyl acetate units. Saponification degree of vinyl acetate component: 99.6 molar, [η)ph O,0
97 l/v, melt index 5. (1/l0 min (1
90℃, load 2160F) EVOH 40 weight '1k
EVOH (copolymer D) obtained by mixing WL with
Table 1 also shows the properties of a case where a cylindrical cup was molded in the same manner as in Example 1 (Comparative Example 3), except that the same procedure was used as in Example 1 (Comparative Example 3).

Table 1 (Note 1) Transparency (Note 2) Cracks (Note 3) Stretching unevenness (Note 4) Oxygen transmission rate After conditioning the cup to equilibrium in an atmosphere with a temperature of 20°C and relative humidity of 65% and 85%. The oxygen permeability was measured using a gas permeation tester under the same atmosphere.

Example 2 The content of acrylonitrile units is 2.0 mol, the content of ethylene units is 42.2 mol, and the content of vinyl acetate units is 55.
8 mol of acrylonitrile-ethylene-vinyl acetate copolymer was saponified to a degree of saponification of the vinyl acetate component of 99.
5 mole attack, [η)ph o, o 961/? , melt index (190℃, load 216or) 4.7f/
A 10-minute copolymer (copolymer E) was obtained.

Using the copolymer, a laminate sheet of 3 types and 5 layers was obtained using the same extruder and T-die as in Example 1. The resin used for molding is the above-mentioned copolymer E for the intermediate layer, and polystyrene (Idemitsu Petrochemical, trade name: Idemitsu Styrene ET) with melt index (200°C, load 5000F'13r/10 minutes) for the inner and outer layers.
-11), the adhesive layer has a melt index (190°C, load 21602) 2? /10 minutes maleic anhydride-modified ethylene-vinyl acetate copolymer (Toyo Soda, trade name Mercene M-5420). Molding temperature is middle layer extruder 18
0 to 225°C, extruder for inner and outer layers 150 to 220°C, extruder for adhesive layer 130 to 220°C, die 220°C.

After a long time, the laminated sheet was subjected to 1. Inner diameter (D) is Loo
A cylindrical cup with a depth L) of 200 m (drawing ratio L/D=2), a wall thickness of 0.5 m, and an internal volume of 1.61 was obtained.

The thickness ratio of outer layer: adhesive layer; middle layer; adhesive layer: inner layer is 45
:2.5:5:2.5:45.

The properties of the cup are shown in Table 2.

In addition, as a control example, saponification of a vinyl acetate component obtained by saponifying an ethylene-vinyl acetate copolymer with an ethylene unit content of 42.2 mol and a vinyl acetate unit content of 57.8 mol! 99.5 molti, mol ph 0.0981/
? , Meni Toy 7 Decks (190℃, load M 2160
? ) When a cylindrical cup was molded in the same manner as in Example 2 except that 4.85'/I 0 min (QEVOHC co-merged F) was used in the intermediate layer (Control Example 4), the content of isobutyne units was 1. The saponification degree of the vinyl acetate component obtained by saponifying the inbutene-ethylene-vinyl acetate copolymer is 99.4 mol%, the content of ethylene units is 42.3 mol%, and the content of vinyl acetate units is 355.9 mol%. , [η]ph
O,092i7y, melt index (190
When a cylindrical cup was molded in the same manner as in Example 2, except that fcEVOH (copolymer G) modified with 7.3 f/lo of isobutyne was used for the intermediate layer (Comparative Example 5) , furthermore the content of ethylene units is 42.2
Mol%, degree of saponification of vinyl acetate component obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate unit content of 57.8 mol, [η] ph 0.097
A'/? , melt index (190℃, load 12
16(1) 4.5f/10min EVOH (Copolymer H)
Table 2 also shows the properties of a case in which a cylindrical cup was molded in the same manner as in Example 2 (Comparative Example 6), except that the material was used for the intermediate layer.

Table 2 (Note 1) The meanings of ○, Δ, and × in the appearance are the same as in Table 1. (Note 2) If copolymer H is used and A large amount of gel is produced in the extruder.

Molding for more than 5 hours was difficult. When other resins were used, it was possible to continue molding in a stable state for over 100 hours.

Example 3 Contains acrylonitrile units iii O, 5 molti, ethylene units z2s, z molti, vinyl acetate units f
Saponifying acrylonitrile-ethylene-vinyl acetate copolymer of t71.3 molty, saponification degree of vinyl acetate component 99.6 molty, [η]ph O, 1251/l melt index (190°C, load ff 1216oy) 0 ．．
A copolymer (copolymer 1) having a weight of 73 f/l and 0 minutes was obtained.

Using the copolymer, pipes of 3 types and 5 layers were molded in the same manner as in Example 1 using 3 types of extruders and 5 coextrusion dies. The resin used for molding has an intermediate layer of the above-mentioned copolymer I,
The inner and outer layers and the adhesive layer are the same as in Example 1, and are made of polypropylene and maleic anhydride-modified polypropylene, respectively. The molding temperature is 190-235°C in the extruder for the middle layer.
Extruder for inner and outer layers: 200-240°C, extruder for adhesive layer: 16
0, ~240°C, die 240°C. The wall thickness of the pipe thus obtained was approximately 10 m, the inner diameter was 30 W, the length was 3
The thickness ratio of each pipe was 100:2:5:2:100. Next, after heating the nuclide layer pipe to 160°C, its both ends are sandwiched between clamps, first stretched in the longitudinal direction of the pipe, then sandwiched between blow molds, and then expanded in the tangential direction with compressed air pressure and blown. I did the molding. The obtained biaxially stretched blow bottle is a cylindrical bottle with an inner diameter of 100 cm, a height of 150+ m, an average wall thickness of the body of 0.6 mm, and an internal volume of 1180 cc. The properties of the bottle are shown in Table 3.

In addition, as a control example, ethylene containing 28.4 moles of ethylene units and 71.6 moles of vinyl acetate units were used.
Saponification degree of vinyl acetate component obtained by saponifying vinyl acetate copolymer: 99.4 molar ratio, [η]phO, 1281/f
, melt index (200℃, load 2160f) 1
When a cylindrical bottle was molded in the same manner as in Example 3 except that 0f/10 min EVOH (Copolymer J) was used in the intermediate layer (Control Example 7), the content of 1-butene units was 0.6 mol. Saponification degree of vinyl acetate component obtained by saponifying 1-butene-ethylene-vinyl acetate copolymer with ethylene unit content 28.1 mol and vinyl acetate unit content 71.3 mol 99.5 mol %, I near 7] I) h O,1
251/W, melt index (190℃, load 21
6(1)0.72? /1/10 E modified with 1-butene
Table 3 also shows the properties of a cylindrical bottle molded in the same manner as in Example 3 (Comparative Example 3) except that VOH (Kyoelectric Combined K) was used as the intermediate layer.

(Note) The meanings of ○, △, and × in the appearance are the same as in Table 1.

Claims (3)

[Claims] (1) Content of acrylonitrile units: 0.1 to 3 mol%,
Obtained by saponifying a terpolymer containing 20 to 55 mol% of ethylene units and the remainder consisting of vinyl acetate units,
A gas permeable laminate comprising at least two layers: a layer of a copolymer having a saponification degree of vinyl acetate component of 98 mol% or more and a layer of another thermoplastic resin. (2) Thermoplastic resin is polypropylene, polyethylene,
Gas permeation resistance according to claim 1, which is at least one resin selected from ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, thermoplastic polyester, polyamide, polystyrene, polyvinyl chloride, and polycarbonate. laminate. (3) The gas permeation-resistant laminate according to claim 1, wherein the laminate is a laminate for food packaging.