JPH09328592A - Thermoplastic resin composition and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ethylene-vinyl alcohol copolymer composition excellent in transparency, gas-barrier properties, moldability, pinhole resistance, impact resistance, spreadability, etc. SOLUTION: The thermoplastic resin composition comprises an ethylene-vinyl alcohol copolymer (A), which contains 40-85mol% vinyl alcohol, and an ethylene-(meth)acrylic acid-(meth)acrylic ester copolymer ionomer (B), which contains 1-10wt.% (meth)acrylic acid neutralized with a metallic cation and 3-25wt.% acrylic ester in terms of (meth)acrylic acid, in a weight ratio of A:B=85:15 to 65:35, the ratio of the melt flow rates(MFR) of A to B being 0.5<MFR(B)/MFR(A)<3.0 as measured according to JIS K 7210 (190 deg.C, 2,160g load).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to improvement in flexibility, impact resistance and pinhole resistance of ethylene / vinyl alcohol copolymer. More specifically, it relates to an ethylene / vinyl alcohol copolymer composition suitable as a packaging material having excellent transparency, gas barrier property, flexibility, impact resistance, pinhole resistance, and moldability.

[0002]

2. Description of the Related Art Ethylene with a high vinyl alcohol content
Vinyl alcohol copolymers are widely used as packaging materials because of their excellent transparency and gas barrier properties. However, the copolymer is not good in moldability, flexibility, impact resistance and pinhole resistance, and when it absorbs moisture, the gas barrier property is deteriorated. Therefore, in many cases, other materials such as olefin polymer are used. It is used by stacking with coalesced or polyamide.

For the purpose of improving the above-mentioned drawbacks of the ethylene / vinyl alcohol copolymer, or improving the interlayer adhesion between the ethylene / vinyl alcohol copolymer and other materials to be laminated, many polymers are treated with ethylene. It has been proposed to blend it with a vinyl alcohol copolymer (for example, JP-A-49-35482, JP-A-49-39678,
50-128793, 52-77160, etc.).

As one of them, there are many proposals for a method of blending a small amount of an ionomer with an ethylene / vinyl alcohol copolymer mainly for the purpose of enhancing the adhesive force of the ethylene / vinyl alcohol copolymer with the olefin polymer layer. Can be seen. In each of these proposals, as the ionomer, Surlyn registered trademarks 1605 and 165, which were commercially available at the time,
0, 1652, 1706, 1707 and the like have been used.

When such an ionomer is blended with an ethylene / vinyl alcohol copolymer, not only is the gas barrier property not so sacrificed but the adhesion to the olefin polymer is improved, and at the same time, the copolymer is improved. Molding processability,
Spreadability, impact resistance, pinhole resistance, etc. can also be improved. However, depending on the application, the degree of improvement in pinhole resistance may not be sufficient, so the method of increasing the amount of the ionomer compounded in order to achieve higher pinhole resistance sacrifices transparency. Therefore, it was not something that I could adopt.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present inventors
Studies were conducted to achieve an improvement that could impart a higher degree of pinhole resistance without impairing the excellent gas barrier properties and transparency of the ethylene / vinyl alcohol copolymer. As a result, the object can be achieved by blending a predetermined amount of an ionomer of an ethylene multi-component copolymer having a specific composition, and at the same time, improvement of molding processability, spreadability, impact resistance and interlayer adhesion with other materials to be laminated. The present invention has been reached by discovering that they can be performed at the same time.

Therefore, an object of the present invention is to provide an ethylene / vinyl alcohol copolymer composition excellent in transparency, gas barrier property, molding processability, pinhole resistance, impact resistance, spreadability and the like. is there. The present invention also provides a packaging material that utilizes such a composition and exhibits excellent performance.

[0008]

According to the present invention, an ethylene / vinyl alcohol copolymer (A) having a vinyl alcohol content of 40 to 85 mol% and a metal cation neutralized in terms of (meth) acrylic acid. (Meth) acrylic acid content of 1
10% by weight, (meth) acrylate content 3-2
Composition containing 5% by weight of ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer ionomer (B) in a weight ratio of (A) :( B) = 85: 15 to 65:35. Consisting of objects, JIS K721
The ratio of the melt flow rate (MFR) of (A) and (B) measured at 0 (190 ° C., 2160 g load) is 0.5 <MFR (B) / MFR (A) <3.0. And a thermoplastic resin composition.

The present invention also relates to packaging material comprising the above composition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, among ionomers, the content of (meth) acrylic acid neutralized with a metal cation is 1 to 10% by weight in terms of (meth) acrylic acid, and a (meth) acrylic acid ester is used. An ionomer of an ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer having a content of 3 to 25% by weight is selected, and this is used as a specific amount ratio and melt flow rate ratio for the ethylene / vinyl alcohol copolymer. It is characterized by combining with, by this, molding processability, without impairing the transparency, gas barrier property and the like of the ethylene / vinyl alcohol copolymer,
Pinhole resistance, impact resistance, spreadability, etc. can be significantly improved. In addition, in this specification, (meth) acrylic acid represents acrylic acid or methacrylic acid.
The content of (meth) acrylic acid neutralized with a metal cation is represented by the weight of (meth) acrylic acid without considering the weight of the metal cation.

The ionomer used in the present invention is a copolymer containing three components of ethylene, (meth) acrylic acid and (meth) acrylic acid ester, and (meth) acrylic acid is neutralized with a metal cation. By containing these in the above proportions, good compatibility with ethylene / vinyl alcohol copolymers having a strong hydrogen bond is exhibited, and the thermoplastic resin composition comprising them is unexpectedly above-mentioned. It shows the combination characteristics of.

On the other hand, Japanese Patent Laid-Open No. 49-39678 discloses that in a plastic bottle comprising a polyolefin layer and an ethylene / vinyl alcohol copolymer layer, a carbonyl group-containing polymer is blended in at least one of the layers to obtain interlayer adhesiveness. It has been proposed that the ionomer is included as one of the carbonyl group-containing polymers, and the possibility of using a multi-component copolymer as the ionomer. There is no mention or suggestion of use and improvement of pinhole resistance by using it.

The ethylene / vinyl alcohol copolymer used in the present invention has a vinyl alcohol polymerization component of 40 to 85.
It is contained at a ratio of mol%, preferably 50 to 75 mol%, and other monomers may be contained as long as they are about 10% or less. The best way to obtain such a copolymer is to have a vinyl acetate content of 40-85 mol%, preferably 5%.
95% ethylene-vinyl acetate copolymer of 0-75 mol%
%, Preferably 98% or more.

When the content of vinyl alcohol in the copolymer is more than the above range, heat resistance and processability are deteriorated, and when it is less than the above range, gas barrier property is deteriorated, which is not preferable.

The ethylene / vinyl alcohol copolymer also has a melt flow rate at 190 ° C. under a load of 2160 g of 0.1 to 50 g / 10 minutes, especially 0.5 to 50 g.
It is preferable to use the one of 10 g / 10 minutes.

The ionomer used in the present invention is an ionomer of an ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, which is neutralized with a metal cation (meth) in terms of (meth) acrylic acid. The acrylic acid content is in the range of 1.0 to 10% by weight, preferably 1.5 to 7% by weight, and preferably the total (meth) acrylic acid content including the unneutralized one is 5 to 20% by weight. %, More preferably 6 to 15% by weight, and the (meth) acrylic acid ester content is 3 to 25% by weight, preferably 5 to 20% by weight.

Examples of the (meth) acrylic acid ester include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, and acrylic acid n.
Examples thereof include butyl, 2-ethylhexyl acrylate, methyl methacrylate, isobutyl methacrylate and the like.

If a metal cation-neutralized (meth) acrylic acid content of less than 1.0% by weight is used in the above copolymer, the compatibility with the ethylene / vinyl alcohol copolymer decreases. , It becomes difficult to obtain a composition having good transparency, and when the content of the (meth) acrylic acid neutralized with a metal cation exceeds the above range, there is a problem that the ionomer becomes hard and brittle. Not only easy, but also easy to absorb moisture, so that the handling property becomes a problem.

Further, when the content of the (meth) acrylic acid ester in the copolymer is less than the above range, it is difficult to highly improve the pinhole resistance while maintaining the transparency of the composition. Become. Further, even if the content of the (meth) acrylic acid ester is more than the above range, further improvement of the physical properties of the composition cannot be expected, and the production cost thereof becomes high, so that it is not preferably used.

The metal cation in the ionomer is a monovalent metal ion such as lithium, sodium or potassium,
Although divalent metal ions such as magnesium and zinc can be illustrated as a typical example, it is particularly preferable to use a sodium ionomer because a composition having large pinhole resistance can be easily obtained.

The ionomer also has a temperature of 190 ° C.
The melt flow rate under a load of 160 g is 0.05
It is preferable to use those having a concentration of -100 g / 10 min, particularly 0.5-10 g / 10 min.

In order to obtain a composition having good transparency, the ethylene / vinyl alcohol copolymer (A) and the ionomer (B) have a melt flow rate ratio of 0.5.
It is necessary to select and combine ionomers that satisfy <MFR (B) / MFR (A) <3.0, preferably 0.7 <MFR (B) / MFR (A) <2.5. When the melt flow rate ratio is out of the above range, sufficient mixing cannot be performed by an ordinary melt kneading device,
It is not possible to obtain a composition having excellent transparency.

The mixing ratio of the ethylene / vinyl alcohol copolymer and the above ionomer is 65 to 85 parts by weight of the former,
The latter is 35 to 15 parts by weight, preferably 30 to 20 parts by weight (total 100 parts by weight) with respect to 70 to 80 parts by weight.

When the proportion of the ionomer is less than the above range, the pinhole resistance is not sufficiently improved. On the other hand, when the proportion of the ionomer exceeds the above range, the transparency and the gas barrier property are deteriorated, which is preferable. Absent.

The thermoplastic resin composition of the present invention can be easily obtained by melt-kneading the ethylene / vinyl alcohol copolymer and the ionomer with a usual melt-kneading device.

The thermoplastic resin composition of the present invention may also contain various additives if necessary. Examples of such additives include antioxidants, heat stabilizers, weathering stabilizers, antistatic agents, lubricants, antiblocking agents, pigments,
Examples thereof include dyes and inorganic fillers.

The composition of the present invention can be used in various packaging materials by taking advantage of the above-mentioned characteristics. Such packaging materials can be used in the form of films (unstretched films, shrink films, etc.), sheets, cups, trays, bottles, tubes, cans, paper cartons, bag-in-boxes and the like. These molded articles are produced by well-known methods such as extrusion molding, injection molding, blow molding, pressure molding,
It can be easily manufactured by a molding method such as press molding. Although these molding temperatures differ depending on the raw materials used, they are usually about 180 to 240 ° C.

Such a molded article may be composed only of the composition of the present invention, or may have a multi-layer structure of two or more layers with other various base materials. Other substrates that can be laminated include, for example, polyethylene, polypropylene,
Polyolefins such as poly-1-butene and poly-4-methyl-1-pentene, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid ester copolymer,
Ethylene / (meth) acrylic acid copolymer or its ionomer, ethylene / (meth) acrylic acid / (meth)
Acrylic ester copolymer or its ionomer, ethylene copolymers such as ethylene / (meth) acrylic acid ester / maleic anhydride copolymer, polyamides such as nylon 6 and nylon 66, polyesters such as polyethylene terephthalate ,PVC,
Examples thereof include polyvinylidene chloride, polystyrene, polycarbonate, paper, aluminum foil, aluminum vapor deposition film and silica vapor deposition film. Among these, a laminated packaging material with a substrate having at least one layer of an olefin polymer such as the above-mentioned polyolefins or ethylene copolymers is particularly useful.

When laminating the olefin polymer, a part or the whole of the olefin polymer may be preliminarily graft-modified with an adhesion-imparting monomer such as maleic anhydride, and such a graft-modified olefin polymer. May be used for the adhesive layer to laminate an unmodified olefin polymer.

When the resin composition of the present invention is used as an intermediate layer and a laminate structure having a low moisture absorption resin such as an olefin resin as both outer layers is used, a bad influence due to moisture absorption of the intermediate layer (a decrease in gas barrier property due to moisture absorption, etc.) can be obtained. ) Is suppressed, which is advantageous.

More specifically, the composition of the present invention is C, the olefin polymer is PO, and the modified olefin polymer is modified P.
O, PA for polyamide, PET for polyethylene terephthalate, PS for polystyrene, PVC for polyvinyl chloride
When displaying respectively, PO / C, PO / modified PO
/ C, PO / C / PO, PO / modified PO / C / modified PO
/ PO, PET / C / PET, PS / C / PA / PO,
It can be configured as PO / paper / PO / C / PO.

[0032]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The physical property evaluation methods in the following examples are as follows. Optical property (Haze) Measured according to JIS K6714. -Tensile physical properties According to JIS K6781, tensile speed 500 mm / mi
A tensile test was performed at n, the load at the breaking point was divided by the width and thickness of the film test piece to obtain the stress at the breaking point, and the elongation at that time was obtained as the elongation at the breaking point. -Oxygen permeability: Modern Control, Inc. 50 using an oxygen permeability measuring device (OX-TRAN TWIN)
The oxygen permeability was measured after conditioning at 23 ° C. for 48 hours under% relative humidity.・ Gerbo flex test Using a gelbo flex measuring machine manufactured by Toyo Seiki, twist angle 4
The pinholes when the film was bent under the conditions of 40 degrees and a stroke of 152.4 mm were counted. (1) In a room temperature test, the number of pinholes when bent a predetermined number of times at room temperature is counted. (2) In the -10 ° C test, the number of pinholes when bent 1000 times at -10 ° C was counted.・ Interlayer adhesion strength After peeling off a part of the relevant interface, the test piece was angled at 90 ° using a tensile tester and the crosshead speed was 300 mm / m.
The maximum strength when pulled in was determined.

Examples 1 to 5 and Comparative Example 1 Ethylene vinyl alcohol (EVOH; Eval EP F101A manufactured by Kuraray, 32 mol% ethylene, MFR
(190 ° C.) = 1.3 g / 10 min) and an ionomer of ethylene / methacrylic acid / isobutyl acrylate having a structure shown in Table 1 were dry-blended at a composition ratio shown in Table 1 to form a spiral die having a diameter of 50 mm. An inflation film was prepared with a 30 mm caliber extruder equipped with, a resin temperature of 215 ° C., a film thickness of 30 μm, and a film expansion ratio of 2.3. On the other hand, in Comparative Example 1, EVO
Inflation films of H (Eval EP F101A manufactured by Kuraray) were prepared in the same manner as in Examples 1 to 5.

The resulting film was subjected to transparency (haze) measurement, tensile test, oxygen permeability measurement, and gelbo flex test (room temperature). As a result, as shown in Tables 1 and 2, the resin composition films of Examples 1 to 5 showed almost the same transparency and oxygen permeability as the EVOH film of Comparative Example 1, while exhibiting flexibility and especially pin resistance. The hole property is remarkably improved.

Comparative Examples 2 and 3 Evaluations were made in the same manner as in Example 1 except that the resin composition ratios were changed. If the amount of the ionomer composition is too small relative to EVOH, the effect of improving the pinhole resistance is not sufficient as in Comparative Example 2. Further, when the amount of the ionomer composition is too large with respect to EVOH, the transparency and the oxygen barrier property are impaired as in Comparative Example 3.

Comparative Example 4 Ethylene methacrylic acid having a structure in which the methacrylic acid of the ionomer used in Example 1 was not neutralized at all
Evaluations were made in the same manner as in Example 1 except that the acrylic acid isobutyl ester copolymer was used. If the content of neutralized methacrylic acid in the ethylene ionomer component is too low and the ratio of the melt flow rate of EVOH to the ionomer is not within the above range, the transparency is impaired as in Comparative Example 4.

Comparative Example 5 An ionomer was converted to an ethylene / acrylic acid ethyl ester copolymer (EA content 19% by weight, MFR = 5 g / 10 mi).
The same evaluation as in Example 1 was performed except for changing to n). Similar to Comparative Example 4, the content of the neutralized methacrylic acid in the ethylene ionomer component is too small, and if the ratio of the melt flow rate of EVOH to the ionomer is not within the above range, the transparency is impaired as in Comparative Example 5.

Comparative Examples 6 and 7 Evaluations were made in the same manner as in Example 1 except that the ionomer was changed to an ionomer of ethylene / acrylic acid copolymer. If the acrylic ester content in the ionomer component is not within the above range, it is difficult to highly improve the pinhole resistance while maintaining the transparency of the composition.

Example 6 and Comparative Example 8 The same resin composition as in Example 1 was used as the core layer, the outer layer was a linear low-density polyethylene resin (Ultzex 2022L manufactured by Mitsui Petrochemical Co., Ltd.), and the adhesive layer was modified with maleic anhydride. Three types of five-layer cast film (thickness ratio 5/2/3/2 /) made of polyolefin resin (Mitsui Petrochemical Admer SF730)
No. 5 85 μm thick laminated film), and a multilayer coextrusion cast molding machine (extruder cylinder diameter: outer layer / adhesive layer / core layer = 65/50) equipped with an 800 mm wide coat hanger die.
/ 50 mmφ) and the molding conditions shown in Table 3 were used. On the other hand, in Comparative Example 8, a three-kind five-layer cast film was prepared in the same manner as in Example 6 except that EVOH (Eval EP F101A manufactured by Kuraray) was used as the core layer.

With respect to the obtained film, transparency (haze) measurement, oxygen permeability measurement, gelbo flex test (-
10 ° C.) and a delamination test was performed. As a result, as shown in Table 3, the multilayer film of Example 6 having one layer made of the resin composition of the present invention had almost the same transparency and oxygen permeation as the multilayer film having the EVOH layer of Comparative Example 8. The interlayer adhesion and pinhole resistance are significantly improved while showing the degree.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

INDUSTRIAL APPLICABILITY According to the present invention, the moldability, the impact resistance, the spreadability, the ethylene-vinyl alcohol copolymer, the transparency and the gas barrier property of the ethylene-vinyl alcohol copolymer are not sacrificed so much.
The pinhole resistance etc. could be improved.

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Claims (4)

[Claims] 1. An ethylene / vinyl alcohol copolymer (A) having a vinyl alcohol content of 40 to 85 mol%,
Ethylene having a (meth) acrylic acid content of 1 to 10% by weight and a (meth) acrylic acid ester content of 3 to 25% by weight in terms of (meth) acrylic acid.
A composition containing the ionomer (B) of a (meth) acrylic acid / (meth) acrylic acid ester copolymer in a weight ratio of A: B = 85: 15 to 65:35, according to JIS K721.
The ratio of the melt flow rate (MFR) of A and B measured at 0 (190 ° C., 2160 g load) is 0.5 <MFR (B) / MFR (A) <3.0. Thermoplastic resin composition. 2. The metal cation of the ionomer of the ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer is at least one metal cation selected from potassium, sodium, lithium, magnesium and zinc. Item 2. The thermoplastic resin composition according to item 1. 3. A packaging material having at least one layer comprising the thermoplastic resin composition according to claim 1. 4. The packaging material according to claim 3, comprising at least one olefin polymer layer.