JPS58116150A - Heat-shrinkable laminated film - 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 The present invention relates to a heat-shrinkable laminated film having gas barrier properties and excellent heat resistance and stretchability.

Many fatty foods such as beef and other fatty foods have irregular shapes and irregular sizes. As this sophisticated food packaging method, shrink wrapping using heat-shrinkable film is by far the most commonly used method.

The general operating procedure of this method is to fill a bag-like film with the contents, then remove the air inside the bag under reduced pressure, and then seal the opening by heat sealing or sealing. The film is then introduced into a heating device such as a hot water path or a hot water shirt, and the film is heat-shrinked.

At this time, the contents are often heat-treated to also sterilize them.

During this gradual packaging process, the film may be affected by heat and fat, causing it to be stretched thin locally or, in extreme cases, to rupture.For this reason, the film used for this purpose may In addition to the physical properties required for general packaging films,
In particular, heat resistance and oil resistance are strongly required.

As heat-shrinkable films with gas barrier properties, vinylidene chloride copolymer (hereinafter referred to as pVDo) alone film, ethylene-vinyl acetate copolymer (hereinafter referred to as mvm) and pVDo described in Canada Tokkenro No. 982923 are used. Laminated film (1st gvA/pVD).

/IVA film), JP-A-47-3456
mvm and pVDo in No. 5 and irradiated 1Ilv
A total of 4 films! ill#iI$ 11-8994
No. 4 6, ionomer resin, ethylene-vinyl alcohol copolymer (hereinafter referred to as It-OH), E
There are V-mu laminated films, etc.

Depending on the type of food to be packaged, the pVDo-only film may cause additives such as plasticizers and stabilizers to migrate into the food, which is unfavorable from a sanitary standpoint. Furthermore, in order to maintain bee resistance, the content of additives must be increased, which results in a decrease in gas barrier properties, which is undesirable in terms of food preservation.

Also, the 11VA/pVDO/KVA laminated film, which has drawbacks such as not being able to be heat-sealed, has IVA as an outer layer, so it can compensate for the drawbacks of pVDO alone, but IVA has poor heat resistance and oil resistance. In order to improve the oil resistance of the 1v film, radiation cross-linking is used, but cross-linking of both outer layers is not carried out because this would lead to decomposition of the pVDO in the core layer. Ionomer resin, lt-0
R1II! The laminated film of vmu is co-stretched with It-OH and ionomer resin, so it is stretched with K11ll.
This is one of the reasons why a film with a uniform thickness cannot be obtained due to heat shrinkage, which is one reason why only a small heat shrinkage rate can be obtained at relatively high temperatures. For this reason, there has been a demand in the food packaging field for the development of heat-shrinkable films with good oil resistance, heat resistance, gas barrier properties, and stretchability.

The present inventors previously discovered 4K, which allows a film with excellent oil resistance and heat resistance to be obtained by using a resin with a crystal melting point of 11 G'C or higher for the outer layer, but this time, in the structure of the heat-shrinkable film, Soft vinyl chloride 4Ii fat (hereinafter pr
The present invention was achieved based on the discovery that a heat-shrinkable film with excellent oil resistance, heat resistance, and stretchability can be obtained by using a film (hereinafter referred to as "o") in the outer layer.

The object of the present invention is to provide a heat-shrinkable film that is oil resistant, heat resistant, compressible, and can be easily compressed without causing local micro-singing.

That is, the heat-shrinkable laminated film of the present invention has a gas barrier layer laminated on both sides with an adhesive layer as a core layer, and has a specific gravity of 0.
Ethylene-α-olefin copolymer (13) having a crystal melting point of 110°C to 130°C at 900 to G, 9 easy O vinyl copolymer 1) an outer layer selected from a mixture with 80% by weight or less and an ionomer resin;
** indicates that the outer layer consists of a soft vinyl chloride resin layer.

The outer layer (4) in the present invention is selected from an ethylene-α olefin copolymer (f) having a high crystalline point, a mixture of (1) Tolumam, and an ionomer resin, so it has heat resistance and oil resistance. It has excellent properties and has good elongation. In the present invention, the specific gravity is 0.900-0.1110. Crystal melting point 11
The ethylene-α-olefin copolymer having a temperature of 0-110°C includes ethylene and a small amount of butene-1% pentene-
Copolymers with α-olefins having carbon atoms of 18 or less, such as 114-methyl-pentene-1, hexene-1, and octene-1, are used. Examples of these copolymers include Urtozex, Neozex (all manufactured by Mikata Petrochemical), G Resin (manufactured by L-Nion Carbide), and Dowlex (manufactured by Dow Chemical); (Linear Low Deus
ityPolyethylsus) (hereinafter referred to as I, LD
It is called PIC). If the weight of these substances in the outer layer (A) is less than 20%, the oil resistance decreases.

In addition, as IVA (1) with a crystal melting point of Hm-103°C,
Vinyl acetate content 3~1! % by weight. As the ionomer resin, the anion part of the copolymer of α-olefin such as ethylene or propylene and unsaturated carboxylic acid such as acrylic acid, methacrylic acid, or maleic acid is used as N1, K.
, Mg, Oa, Zn, or other ionically crosslinked products are used. These crystal melting points were measured using a differential scanning calorimeter needle (IB manufactured by PerkinElmer).
W) t' is the temperature at which the melting curve reaches its maximum value.

In the present invention, pVDo used in the gas barrier layer
means vinylidene chloride having a weight of 65 to 9 s, and at least one unsaturated monomer copolymerizable therewith.
It is a copolymer consisting of 38% by weight. Copolymerizable unsaturated monomers include, for example, vinyl chloride, acrylonitrile, ataryl alkyl ester (alkyl group carbon 91
~11 pieces) etc. Of these, vinylidene chloride-vinyl chloride copolymers are common. If necessary, the known lubricant, Stabilizer 31141F, can be added to pVDo.

Mt-OH, which is used in the gas barrier layer, is a partially saponified resin of ethylene and vinyl acetate copolymer.
Ethylene book emergency go-go4 decoration, saponification degree go% Rula or higher is used for overcurrent.

Ethylene-α-olefin copolymer (1) and νvD.

Since It-OH does not inherently have phase S properties, its laminate can be peeled off.
Since ft-OH and the bonding material also contain a plasticizer in the soft PVC, it is difficult to bond them together. Therefore, in the present invention, it is necessary to provide a strong adhesive layer on both interfaces of the gas barrier layer to prevent layer peeling. For the adhesive layer, bipolymers such as carboxylic acid-modified polyolefin, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, etc., and even combinations with vinyl acetate can be used. A terpolymer, a styrene-butadiene block copolymer, etc. are used.

The soft pro layer forming the outer layer in the present invention has a pV
20 to 20 parts by weight of plasticizer per 100 parts by weight of C or its copolymer
80 parts by weight was added. As the plasticizer, known low molecular plasticizers and polymer plasticizers are used. As low-molecular plasticizers, polybasic acid aliphatic alkyl esters such as dioctyl adipate, dioctyl sebacate, and dibutyl pacate are generally used. Examples of polymer plasticizers include oligomers with a molecular weight of 1 to 10,000, such as dibasic acids such as adipic acid, sebacic acid, and azelaic acid, and polyhydric alcohols such as ethylene glycol, propylene glycol, and butylene glycol. It is a co-condensate, and there are polyester oligomers with -basic acids or alcohols as terminal groups, if necessary. Among these, tL? produced from a polyhydric alcohol whose alkyl group has 6 to 1 ot) lIIJj group dicarmedicarboxylic acid number 2 to @? : Polynyester oligomers having a molecular weight of 1,000 to 1,000.41 and 1,100 to 1,000 are preferably used. soft p
ro is also an omniscient stabilizer and layering agent.

Additives such as colorants can be added as necessary.

When the multilayer film of the present invention is used for food packaging, it is preferable for heat sealing to use the soft pVo layer as an outer layer that does not come into contact with food. The thickness of the entire film layer is generally preferably 20 to 120 microns.

The laminated film of the present invention is extruded into a cylindrical shape using an extruder according to the number of laminated layers, and a cylindrical one is extruded using an annular die similar to JP-A No. 58-82888, and a flat one is extruded into a cylindrical shape using an annular die similar to JP-A-58-82888. are extruded into a flat shape and laminated using a known T-die. According to the present invention, the cylindrical laminate was stretched using a two-wheel inflation method and the flat laminate was stretched using a tenter according to a general method to obtain the desired heat-shrinkable film. Heat-shrinkable stretched films have excellent oil resistance, heat resistance, gas barrier properties, and uniform thickness, and are suitably used for packaging fatty foods that require high-temperature sterilization. Examples will be described below, but the present invention is not limited to these examples as long as the invention is within the scope of the claims.

EXAMPLES A resin consisting of the polymers listed in Table 1 is extruded separately in a plurality of extruders, and the S* material flows into a coextrusion annular die where it is formed into a laminate. The cylindrical body of the laminate flowing out from the scissor die is cooled in a cooling tank of 15-2h"C and has a flat width I.
Hm1 has a cylindrical shape with a thickness of 400 to 470μ. The cylindrical body in the cooling tank is filled with soybean oil to prevent the inner surfaces from sticking together.

Next, the cylindrical body was heated for about 12 seconds while being fed at a speed of 511/min through the jointed hot water bath so as to reach the stretching temperature shown in No. 4H. It is passed through a tube roller at a rotation speed of iIK/4). While the cylindrical body is cooled at room temperature, 1! By the time the air passes through the second nip roller, which rotates at a rate of It/min, the air is stretched 3 times in the longitudinal direction and is sent into the cylindrical body.
It was expanded twice and stretched in the transverse direction. The resulting lazily stretched film had a folding value of about 350 mm and a thickness of about 48 to 54 #.

The physical properties of the polymer used in the examples are shown in ill, the layer structure of the laminated film obtained in the examples is shown in S@, the physical property test method of the obtained film is shown in Table 3, and the physical property test of the film is shown in Table 4. Show the results.

ml Composition of 100 parts of vinylidene chloride/vinyl chloride-80/20 copolymer and 1 part of epoxy soybean oil 42 Trade name Kobar (manufactured by Kuraray) Ethylene-containing 45
Molarity * 3 let taoo tr) pV°100sK
* +7 zxjx Yooligomer (KBA-15
Daihachi Chemical g) So part, composition of stabilizer (tin-based stabilizer and calcium stearate mixture) 31B
3 Qin 4 Composition of 100 parts of pV0 with polymerization degree of 700, 5011 parts% of dioctyl adipate KBA-15 (*3 Same as above) 20 parts of area, 2 parts of stabilizer (same as *3) *5 #J Product name Mikata Petrochemical) Hata 6
Product name: NEOSEX (###) *7 Adhesive resin model (manufactured by 5-I Yuka) Low-density polyethylene paste Qin 5III Product name: Hi (Ran (manufactured by Sankata Polychemical) 3rd table column foot measure measurement method heat Water shrinkage rate When 20 sheets of film cut into 103X I 0cts are contracted in a relaxed state for 1 minute in a 90C hot water bath, the average shrinkage rate with respect to the original length in the vertical and horizontal directions Oil resistance and heat resistance An oil tube was intentionally placed floating on the surface of a 90°C hot water bath, and vacuum-packed bacon was placed inside it for 3 seconds, followed by grilled pork fillet.
The films were immersed for 0 minutes, then cooled, and the oil resistance of the outer layer and the heat resistance in the bacon recesses were checked, and the presence or absence of damage to the film was examined.
Castle Ga x barrier property 30℃, 10(I
Expressed as the amount of II cable transmission at RH.

=261- and slope moooooo ◎ 1010 Stretchability: Oa good stretchability Film thickness unevenness within 20 factors Δ
It can be stretched, but there is uneven film thickness of 50-70mm x Q stretching is possible, but there is slight necking, and the unevenness of film thickness is 704 or more xx Cannot be stretched, oil resistant ◎ Page and burnt are both ON.

O Bacon OK, X +q■ Heat resistant Q Bacon and 918 pork are both OK.

0 Bacon OK lx Not possible All the stickers were Gassho Heaton rules.

As is clear from Examples 1 to 6 in Table 4, the heat-shrinkable film according to the present invention has extremely excellent stretchability, sufficient heat shrinkage rate at 90°C, and oil resistance, heat resistance, and gas barrier properties. Good results were obtained, and comparison examples 1.3 and 1.3 were not able to elongate. Comparative example 2
Although it was possible to stretch, slight necking occurred and the stretchability was unstable. Comparative Example 4Vi stretchability is somewhat unstable,
Moreover, oil resistance was also poor.

Agent Yoshio Kawaguchi

Claims (1)

[Claims] The core layer is a gas barrier layer laminated on both sides of the Tllm adhesion layer, and is made of an ethylene and α-olefin copolymer ( 1), an outer layer selected from a mixture of cough copolymer (ethylene and vinyl acetate copolymer with a weight of 1120% by weight or more and a crystalline melting point of 11!1-103°C) of not more than 80% and an ionomer resin (4), soft A heat-shrinkable laminated film characterized in that the outer layer is made of vinyl chloride resin (1) A gas barrier layer (1) is made of a vinylidene chloride copolymer or an ethylene-vinyl alcohol copolymer (Summer) The heat-shrinkable laminated film described in Section 1. (3) Ethylene and α-olefin copolymer (!) is an α-olefin copolymer selected from ethylene and butene-1, pentene-1,4-methyl-pentene-1, hexene-1, and octene-1.
The heat-shrinkable laminated film according to claim (1) or @, which is a copolymer with an olefin.