JPH0196275A - Readily openable sealing material - Google Patents

Abstract

PURPOSE:To obtain the titled material having seal face formed by a composition consisting of alpha-olefin-alpha,beta-unsaturated carboxylic acid copolymer (salt), specific ethylene based copolymer and propylene based polymer contained at a specific ratio and having good sealability and opening by hand. CONSTITUTION:The aimed material having heat-sealable faces to be bonded formed by a composition consisting of (A) 5-40wt.%, preferably 10-30wt.% alpha-olefin-alpha,beta-unsaturated carboxylic acid copolymer [e.g. ethylene-(meth)acrylic acid copolymer, preferably having 5-100g/10min melt flow rate at 190 deg.C] or salt thereof, (B) 10-60wt.%, preferably 20-50wt.% ethylene based copolymer obtained by copolymerization of (i) ethylene with (ii) vinyl monomer selected from vinyl acetate and alkyl (meth)acrylate and (C) 20-70wt.%, preferably 30-60wt.% propylene based polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an easy-to-open sealing material, and more particularly:
The present invention relates to an easy-to-open sealing material that has good sealing properties and is easy to open by hand.

Technical background of the invention and its problems There are many types of film materials for food packaging, and there are various proposals regarding single-layer films or multi-layer films.

Generally, heat sealing is performed at the sealing stage, so heat-sealable materials are commonly used for single-layer films, and for multi-layer films, the innermost layer is a heat-sealable material. Those formed with this are commonly used.

As such heat-sealing materials, polyolefin polymers such as polyethylene, polypropylene, or resin compositions in which these general-purpose polyolefins are mixed with ethylene-vinyl acetate copolymer, polybutene-1, and the like are known.

On the other hand, there are cases where the heat-sealing surface is formed of a different material, and cases where the heat-sealing surface is formed of the same material, such as packaging bags for potato chips, instant ramen noodles, snack foods, etc. In the latter case, if the polyolefin material proposed in the past was used, there was a problem in that the sealing strength was stronger than necessary, making it difficult to open the seal by hand.

Various proposals regarding easy-open sealing materials have been made, but most of them have been applied when the heat-sealing surface is formed of a different material. For example, JP-A-60-239
No. 238 has a melt index of 0.5 to 100.
Ionomer resin 100ffiff1 with y/10 minutes
easy-to-open property with an olefin resin as a sealing partner, comprising a heat-sealing layer made by mixing 5 to 65 parts by weight of a combination of ethylene and propylene with an ethylene content of 1 to 50 IH%. A sealing material is disclosed.

However, this easy-open 11 sealing material exhibits fairly good easy-opening properties when the heat-sealed surfaces are made of olefin resin, but when both heat-sealed surfaces are formed from the above-mentioned resin compositions. had the problem that it was not necessarily easy to open.

OBJECT OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above. Has excellent ease of opening and is resistant to a wide range of temperatures.
3. It exhibits appropriate sealing strength and is easy to open, and can be made into a coextruded film with polyolefin materials (especially polypropylene), which are conventionally used as sealing layers in packaging bags for potato chips, instant noodles, snack foods, etc. The purpose is to provide a flexible sealing material.

Summary of the Invention The easy-open seal +4 diagonal according to the present invention comprises (a) α-olefin-α, β-unsaturated carbonic acid consortium or salt thereof: 5 to 40% by weight, (b) ethylene. and (i
i) Ethylene copolymer obtained by copolymerization with a vinyl monomer selected from vinyl acetate and alkyl (meth)acrylate: 10 to 60% by weight, (c) Propylene polymer: 20 to 70% by weight. The heat-sealing surfaces to be bonded together are formed by a composition consisting of the following.

The easy-open sealing material according to the present invention comprises (a) an α-olefin-α,β-unsaturated carboxylic acid copolymer or a salt thereof, (b) a specific ethylene copolymer, and (c) a specific The heat-sealed surface to be bonded is formed by a composition consisting of a propylene-based hand bond, which has excellent IJ properties, excellent ease of opening, and can be used in a wide temperature range. Shows moderate seal strength.

DETAILED DESCRIPTION OF THE INVENTION Each component constituting the easy-open sealing material according to the present invention will be specifically explained below.

(a) α-olefin-α, β-unsaturated carboxylic acid copolymer or metal salt thereof, component (a) used in the present invention is α-olefin-α, β-unsaturated unsaturated silponic acid copolymer. Combined with that metal salt. This α-olefin-α,
The β-, β-carboxylic acid copolymer or its metal salt may also contain other comonomythyl components such as α, β-unsaturated carboxylic acid ester, carboxylic acid vinyl ester, and the like.

Examples of α-olefins include ethylene and propylene, and examples of α,β-unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, and monomethyl maleate. Also α
, β-, β-carboxylic acid esters include alkyl esters having 1 to 8 carbon atoms of acrylic acid or methacrylic acid, such as esters such as methyl, ethyl, propyl, n-butyl, isobutyl, and 2-ethylhexyl. be able to.

Examples of metal salts include monovalent metal ions such as lithium, sodium, potassium, and cesium, divalent metal ions such as zinc, copper, magnesium, calcium, strontium, and barium, and trivalent metal ions such as ammonium and iron. can be used. The resin of component (a) contains 85 to 99.5 mol% of α-olefin units, particularly 94 to 99 mol%, and 0.5 to 15 mol% of α,β-unsaturated carboxylic acid units, particularly 1 to 15 mol%. A copolymer containing 6 mol % and other monomers 0 to 10 mol %, especially 0 to 6 mol %, is preferably converted into a metal salt so that the degree of neutralization is 0 to 100 %, especially 0 to 80 %. .

More specifically, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate-acrylic acid copolymer, ethylene-isobutyl acrylate-methacrylic acid copolymer, or salts thereof For example, these characteristics of component (a) are available on the market.

The resin of component (a) has a melt flow rate of 1
90'C is 0.1~500g/10 minutes, especially 0.5~
It is preferable that it is about 100y/10 minutes.

The resin as component (a) as described above is contained in the easy-open sealing material according to the present invention in an amount of 5 to 40% by weight, preferably 10 to 3%.
It is desirable that it exists in the mother of 0 weights and maximum %. This (a
) If the mother resin of the component is less than 5% by weight, it is not preferable because it does not exhibit excellent easy-opening properties and does not exhibit adequate sealing strength in a wide temperature range;
If it exceeds m%, the sealing strength is too weak and delamination is likely to occur between the polypropylene layer and the sealing layer when forming a coextruded film with polypropylene, which is not preferable.

(b) Ethylene copolymer In the present invention, as the ethylene copolymer (b), (i) ethylene, (ii > vinyl acetate and alkyl (meth)
Those obtained by copolymerization with a vinyl monomer selected from acrylates are used.

Suitable alkyl (meth)acrylates include alkyl esters of acrylic acid or methacrylic acid having 1 to 8 carbon atoms, specifically methyl acrylate,
Representative examples include ethyl acrylate, isobutyl acrylate, methyl methacrylate, edyl methacrylate, in-butyl methacrylate, and 2-ethylhexyl methacrylate. As the ethylene copolymer,
Two or more types of these vinyl monomers may be copolymerized.

The amount of vinyl monomer contained in such an ethylene copolymer is not particularly limited, but it is usually 1 to 50% by weight, preferably 3 to 40% by weight.

It is believed that such an ethylene copolymer plays a role in compatibilizing the (a) component tree 1 and (c) the propylene polymer described below in the easy-open sealing material according to the present invention. This provides an easy-to-open sealing material with appropriate adhesion and unsealability.

Such an ethylene copolymer has a melt flow rate of 0.1 to 500 g/l at 190°C for 0 minutes.

In particular, it is preferably about 0.5 to 1009/10 minutes.

The above-mentioned ethylene copolymer is contained in the resealable seal material according to the present invention in an amount of 10 to 60% by weight, preferably 20 to 60% by weight.
It is desirable that it be present at a maximum of 50% by weight. If the content of the ethylene copolymer is less than 10%, the sealing strength will be weak, and when a coextruded film is formed with polypropylene, peeling will easily occur between the polypropylene layer and the sealing layer, so it is preferable. On the other hand, if it exceeds 60% by weight, it will not show excellent ease of opening and will not show adequate sealing strength in a wide sealing temperature range, and when a coextruded film with polypropylene is formed, there will be a problem between the polypropylene layer and the sealing layer. This is not desirable because it can easily cause peeling in the living room.

(c) Propylene polymer In the present invention, a highly crystalline polymer selected from a propylene monopolymer or a propylene copolymer is used as the propylene polymer.

As the propylene comonomer, a copolymer of propylene and ethylene and/or an α-olefin having about 4 to 8 carbon atoms is used, and the content of ethylene or α-olefin is 0.5 to 20 mol%. , preferably 1 to 10 mol%.

Such a propylene polymer has a melt flow rate of 230°C of 0.1 to 500 s/10 minutes.

In particular, it is preferably about 0.5 to 100 s/10 minutes.

The above-mentioned propylene-based polymer is contained in the easy-open sealing material of the present invention in an amount of 20 to 70%, preferably 30%.
Desirably, it is present in an amount of ~60% by weight. However, if the content of this propylene-based polymer is less than 20w%, it will not exhibit adequate sealing strength in a wide temperature range,
In addition, when coextruded with polypropylene to form a film, it is undesirable because it tends to cause peeling between the polypropylene layer and the sealing layer.On the other hand, if it exceeds 70% by weight, it does not show excellent ease of opening and can be used over a wide range of temperatures. This is not preferable because it does not exhibit adequate sealing strength in this area.

Sealing material In the present invention, the composition for forming an easy-to-open seal containing the above-mentioned components is prepared in the above-mentioned (a) and (b).
This is done by triblending or melt blending the components of L (c) simultaneously or sequentially. In the case of triblend, (a), (
Components b) and (c) are melt-plasticized, uniformly melt-mixed, and extruded. In case of melt blend, single 1t
(B) Melt mixing may be carried out using various mixers such as an extruder, twin screw extruder, Banbury mixer, rolls, various kneaders, etc., and there is no particular restriction on the mixing order.

It is also possible to add antioxidants, weather stabilizers, lubricants, antifogging agents, etc. to the composition within a range that does not affect the performance of the composition.

The composition thus obtained can be used, for example, in polypropylene,
If necessary, high-pressure polyethylene, ethylene-α, β-unsaturated carboxylic acid copolymer, etc. They are laminated using a resin such as a monomer or an adhesive such as an anchor coating agent.

The method for manufacturing the laminate is not particularly limited, but can be performed, for example, by the following method.

(1) Heat fusion method When a pre-formed base material and a sealing layer film are made into a laminate using an adhesive, a method of thermocompression bonding the base material, adhesive, and sealing layer film, or a method of bonding the base material, an adhesive, and a sealing layer film. A method of recuperating pressure bonding is employed in which an adhesive is previously laminated on at least one surface of the sealing layer by coextrusion, extrusion coating, or the like.

(2) Sanderman Tirmination Method This is a method of bonding a base material and a sealing layer via a molten film of adhesive by the T-Guy method or the like.

(3) Co-extrusion method This is a method in which a base material and a sealing layer, or a base material, an adhesive layer, and a sealing layer are laminated by a co-extrusion molding method.

(4) Adhesive method This is a method in which an adhesive is applied to at least one surface of the base material or the sealing layer to bond the pressure pipe.

Of course, these methods include, for example, (4) bonding a base material coated with an adhesive using the adhesive method with a sealing layer via a molten film of another adhesive using (2) the side-id delamination method. It is also possible and necessary to use a combination U as shown in FIG.

In particular, when a base material such as polypropylene is used, the layers can be laminated by a coextrusion lamination method.

In order to improve the adhesion of the base material and the seal layer, the surfaces thereof may be subjected to a known method such as corona treatment in advance.

The thickness of the sealing surface is not particularly limited, but is generally 5 to 2
00 μTrtS is preferably about 10 to 50 μm.

The thus obtained sealing material can be bonded to the same sealing material, and in this case as well, the bonded surface exhibits easy-openability. That is, a sealing material having the easily openable sealing material according to the present invention on a base material as a heat-sealing surface can be heat-sealed so that the heat-sealing surfaces are in contact with each other, and the thus heat-sealed joint The surface has excellent sealing properties and is easy to open.

Moreover, when heat-sealing sealing materials having the easy-to-open sealing material according to the present invention on a base material as a heat-sealing surface, a wide temperature range, for example, 130 to 160'' can be applied.
C shows appropriate seal strength.

Effects of the Invention The easy-open sealing material according to the present invention comprises (a) an α-olefin-α,β-unsaturated carboxylic acid copolymer or a salt thereof, (b) a specific ethylene copolymer, and (c ) The heat-sealing surface to be connected to the pipe is formed by a composition consisting of a specific propylene-based polymer, or it has excellent sealing properties, excellent ease of opening, and a wide temperature range. shows moderate seal strength.

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

The polymers used in the examples and the method for measuring seal strength are shown below.

(1) Polymer used Acid copolymer A (a) Wlil mycopolymer ethylene-methacrylic acid copolymer (acid content: 9% by weight), MFR was 39/1
It is 0 minutes.

(b) Ionomer A: Na salt (degree of neutralization 50%) of edylene-methacrylic acid copolymer (acid content 10 citrate), MFR 1 g/l 0 min.

(c) Ionomer B: Zn salt of ethylene-methacrylic acid combination (degree of neutralization 70%), MFR is 1 a/
It's 10 minutes.

(d) Edylene-vinyl acetate copolymer a (EVAa)
: A combination of ethylene and vinyl acetate (ester content: 19% by market weight), and the MFR is 3y/10min.

(e) Edylene-vinyl acetate copolymer b (EVAb)
: Ethylene-vinyl acetate copolymer (ester content 10%), MFR is 2y/10min.

(f) Polypropylene (PPa): Polypropylene F-600 (homopolymer) manufactured by Mitsui Petrochemical Industries,
The density is 0.919/cm, and the MFR is 10g/10.
minutes (measured temperature 230'C).

(g) Polypropylene (PPb): Polypropylene F-650 (70 pyrene-ethylene random copolymer) manufactured by Mitsui Petrochemical Industries, with a density of 0.9"19/cn
f, and MF'R is 6U/10 minutes (measurement temperature 230'
C).

(h) Low-density polyethylene Low-density polyethylene manufactured by Nimitsui Petrochemical Industries (Mirason M-16>, with a density of 0
．． 92'J/cI11 and the MFR is 43/10 minutes.

(i) Ethylene-ethyl acrylate copolymer: Ethylene-ethyl acrylate copolymer (contains ester, but 19%
), and the MFR is 5y/10 minutes.

(2) Measurement of seal strength Using a single-sided heating type heat seal, seal temperature: 1
20.130.140,150.160.170,18
0'C Seal pressure (actual pressure): 0.20) IPa seal time =
Heat sealing was performed under sealing conditions of 0.5 seconds seal bar width: 10 strips.

The seal strength was measured using a 15 mm wide specimen at a tensile speed of 300 mm/min.

Example 1 2Offl parts of acid copolymer A, 40fflU parts of ethylene-vinyl acetate copolymer a, and 400 weight of polypropylene a were melt-kneaded using a single-screw extruder at a resin temperature of 190'C. This composition was molded into a film having a thickness of 25 μ7n using a T die-cast film molding machine at a resin temperature of 230'C, and one side of the film was subjected to corona treatment.

Next, using a laminator, the above-prepared film and a 12 μm thick polyethylene terephthalate film coated with an isocyanate-based anchor coating agent were bonded together via a 15 μm molten film of low density polyethylene (resin temperature 320'C). .

The obtained laminate was heat-sealed to an acid copolymer using a film layer of a composition consisting of ethylene-vinyl acetate copolymer a and polypropylene a as a sealing layer, and the sealing strength was measured using a tensile tester. did.

The results are shown in Table 1.

It has excellent sealing properties in terms of heat-sealing performance, excellent ease of opening, and exhibits appropriate sealing strength over a wide temperature range.

Next, the above composition was co-extruded with polypropylene to form a film to see if it could be easily opened in practical use.

A polypropylene a/composition 15μ7rL/10μm21i film was prepared using T-die cast film molding using the above composition and polypropylene a at a resin temperature of 230'C, and the polypropylene layer side was subjected to Flon treatment.

Next, using a laminator, the prepared film and a 12 μm thick polyethylene terephthalate film coated with an isocyanate-based anchor coating agent were bonded together via a 15 μm thick molten film of low density polyethylene (resin temperature 320° C.). The resulting laminate (bonded so that the polypropylene layer side was in contact with the low-density polyethylene layer side) was heat-sealed under 160° C. sealing conditions in the same manner as described above, and the seal strength was measured using a tensile tester.

The results are shown in Table 1.

This shows that even when made into a film coextruded with polypropylene, it exhibits easy-opening properties.

Examples 2 to 3 The same tests as in Example 1 were conducted except that ionomer A (Example 2) or ionomer 8 (Example 3) was used instead of the acid copolymer.

The results are shown in Table 1.

Example 4 The same test as in Example 3 was conducted except that ethylene-3Y[M vinyl copolymer A was used instead of ethylene-vinyl acetate copolymer a.

The results are shown in Table 1.

Example 5 The same test as in Example 3 was conducted except that polypropylene b was used instead of polypropylene a.

The results are shown in Table 1.

Example 6 In Example 2, the ratio of ethylene-vinyl acetate copolymer a and polypropylene a to the ionomer was changed to 20%.
The same test as in Example 2 was conducted except that the ratio was changed to 20:60.

The results are shown in Table 1.

Example 7 In Example 3, the ratio of ionomer B, ethylene-vinyl acetate copolymer a, and polypropylene a was 10:
The same test as in Example 3 was conducted except that the ratio was changed to 60:30.

The results are shown in Table 1.

Comparative Example 1.2.3 In Example 3, the ratio of ionomer B, vinyl acetate copolymer a, and polypropylene a was 3:10:87 (
Comparative example 1), or 60:10:30 (comparative example 2), or 20 near 0:10 (comparative example 3).
A test similar to Example 3 was conducted.

The results are shown in Table 1.

Example 8 The same test as in Example 3 was conducted except that ethylene-ethyl acrylate polymer a was used instead of ethylene-vinyl acetate copolymer a.

The results are shown in Table 1.

Claims (1)

[Scope of Claims] (a) α-olefin-α,β-unsaturated carboxylic acid copolymer or salt thereof: 5 to 40% by weight, (b) (i) ethylene, (ii) vinyl acetate and alkyl A composition consisting of an ethylene copolymer obtained by copolymerization with a vinyl monomer selected from (meth)acrylates: 10 to 60% by weight, and (c) a propylene polymer: 20 to 70% by weight. An easy-to-open sealing material, characterized in that a heat-sealing surface to be bonded is formed with the above.