KR100344909B1 - Packaging - Google Patents

Abstract

The present invention,

(A) A blended resin layer comprising a polyester resin containing at least 70 mol% of polyethylene naphthalate-forming units and a polyester resin layer containing at least 70 mol% of polyethylene terephthalate-forming units as the outermost layer, or Polyester resin layer containing 70 mol% or more of polybutylene terephthalate-forming units;

(B) a gas-blocking resin layer; And

(C) In an innermost layer, comprising a heat-sealable resin layer, wherein the resin container (A), (B) and (C) are arranged in the above order, in a packaging container containing a heat-sealed unstretched laminated film. It is about. These packaging containers showed good label adhesion and pinhole resistance.

Description

Packing container

The present invention relates to a packaging container, and more particularly a packaging container suitable as a food packaging container for packaging foods such as ham and sausages when producing them.

In general, ham and sausages are prepared by filling their raw materials in a container consisting of shrinkable films and then heat treating the raw material in the container in a retainer. Prior to marketing these foods, printing labels are affixed to the surface of the food filled containers. The adhesion of the printing label to the surface of the food-filled container is adversely affected by the moisture present on the label-adhesive surface of the food-filled container so that the surface of the container does not need to be dried before the label is applied. It is desirable that moisture can be easily removed from the surface of the food-filled container taken out from the retainer. In addition, packaging containers having a good water release or removal property and a surface with good label adhesion even after washing with water have been required for packaging not only food but also various other products. In addition, packaging containers are required to have good pinhole resistance in their transportation.

As a result of the inventor's research, (A) the compounding resin layer which contains as a outermost layer the polyester resin containing a predetermined amount of polyethylene naphthalate-forming units, and the polyester resin containing a predetermined amount of polyethylene terephthalate-forming units. Or a polyester resin layer containing a predetermined amount of polybutylene terephthalate-forming unit, (B) gas-blocking resin layer and (C) innermost layer, wherein a heat-sealable resin layer is laminated in the above order, and By heat sealing the obtained laminated film, it was found that the obtained packaging container exhibited excellent label adhesion and pinhole resistance. Based on the above findings, the present invention has been achieved.

It is an object of the present invention to provide a packaging container capable of exhibiting excellent label adhesion and pinhole resistance.

A first aspect of the present invention for achieving the above object is a polyester resin containing at least 70 mol% of (A) polyethylene naphthalate-forming unit and a polyester containing 70 mol% or more of polyethylene terephthalate-forming unit. A blended resin layer containing a resin layer or a polyester resin layer containing 70 mol% or more of a polybutylene terephthalate-forming unit; (B) a gas-blocking resin layer; And (C) a heat-sealing resin layer, wherein the resin layers (A), (B) and (C) are such that the resin layer (A) is disposed as the outermost layer and the resin layer (C) is disposed as the innermost layer. It is to provide a packaging container produced by heat-sealing the unoriented laminated film laminated in the above order.

A second aspect of the present invention provides a blended resin layer comprising (A) a polyester resin containing 70 mol% or more of polyethylene naphthalate-forming unit and a polyester resin containing 70 mol% or more of polyethylene terephthalate-forming unit, Or a polyester resin layer containing 70 mol% or more of a polybutylene terephthalate-forming unit; (D) adhesive resin layer; (B) a gas-blocking resin layer; (D) adhesive resin layer; And (C) a heat sealable resin layer, wherein the resin layers (A), (D), (B), (D) and (C) have a resin layer (A) disposed as the outermost layer and a resin layer ( It is to provide a packaging container manufactured by heat-sealing a non-stretched laminated film laminated in this order such that C) is disposed as the innermost layer.

A third aspect of the present invention is to provide a food packaging container including the packaging container defined in the first or second aspect.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The packaging container according to the present invention can be produced by heat sealing an unoriented laminated film. The unstretched laminated film comprises a blended resin layer comprising at least (A) a polyester resin containing at least 70 mol% of polyethylene naphthalate-forming units and a polyester resin containing at least 70 mol% of polyethylene terephthalate-forming units, Or a polyester resin layer containing 70 mol% or more of a polybutylene terephthalate-forming unit; It has a multilayer structure which includes laminating (B) a gas-blocking resin layer and (C) heat-sealing resin layer in order of resin layer (A), (B), and (C). Further, in a preferred embodiment of the present invention, an adhesive resin layer can be inserted between adjacent resin layers.

Each polyester resin constituting the resin layer (A) may contain not only homopolymers but also copolymers.

Because polyester resins are composed of homogeneous polymers such as polyethylene naphthalate (PEN) resins, polyethylene terephthalate (PET) resins or polybutylene terephthalate (PBT) resins, some known methods that can typically be used for the production of films are known. Examples of the resin may be used.

For polyester resins composed of copolymers, the PEN-forming units, PET-forming units or PBT-forming units in each polyester resin are preferably 85 to 99 mol%.

The component of the above-mentioned copolymer is as follows. That is, isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxybenzoic acid) etc. are mentioned as a dicarboxylic acid component of a copolymer. As the glycol component of the copolymer, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 1,4-cyclohexane dimethanol, neopentyl glycol, polyethylene oxide glycol, polypropylene oxide glycol, polytetramethylene oxide. Glycol etc. can be mentioned. Any two or more kinds of these dicarboxylic acid components and glycol components can be used in combination.

When the resin layer (A) contains a compounding resin, the weight ratio of PEN resin to PET resin can usually be selected from the range of 1: 0.5 to 1: 2.

As the polyester resin composed of a copolymer, a polyester resin containing 70 mol% or more of a polybutylene terephthalate-forming unit is preferable. In this case, as the copolymerization component of the polyester resin, polytetramethylene oxide glycol preferably having a number average molecular weight of 300 to 6,000, more preferably 500 to 2,000 can be suitably used. The use of copolymerized PBT resins satisfying the above requirements makes it possible to produce films exhibiting higher pinhole resistance compared to homopolymerized PBT resins, due to their good low temperature stretchability as well as good flexibility without damage to heat resistance. Such copolymerized PBT resins preferably have a melting point of 200 to 223 ° C, while homopolymerized PBT resins have a melting point of 225 ° C.

The polyester resin constituting the resin layer (A) may further contain an anti-sticking agent composed of organic or inorganic particles in order to reinforce the anti-blocking property of the manufactured packaging container during stack storage.

Examples of the anti-sticking agent composed of organic particles include particles composed of homopolymers or copolymers of polystyrene, polyethylene, polyamide, polyester, polyacrylic acid ester, polymethacrylic acid ester, epoxy resin, polyvinyl acetate, polyvinyl chloride and the like. I can lift it. This organic particle may further contain a crosslinking agent. Examples of the anti-sticking agent composed of inorganic particles include talc, kaolin, silica, calcium carbonate, glass powder, and the like.

The anti-sticking agent may typically have an average particle diameter of about 1 to about 10 μm. The amount of the anti-sticking agent is usually 100 to 10,000 ppm, preferably 1,000 to 5,000 ppm, on a resin basis. In the present invention, it is preferable to use an anti-sticking agent composed of organic particles. Among them, it is more preferable to use organic particles composed of polyacrylic acid ester or polymethacrylic acid ester.

The gas-blocking resin layer (B) is made of polyamide (PA), a saponified product of ethylene-vinyl acetate copolymer (EVOH), polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and polycarbonate (PC). And any resin selected from the group consisting of: Among these resins, saponified product (EVOH) of polyamide (PA) or ethylene-vinyl acetate copolymer is preferred, and polyamide (PA) is more preferred.

In the present invention, a polyamide obtained by polycondensation reaction between each raw material, such as (1) 3-membered or more lactam, (2) polymerizable ω-amino acid or (3) polycondensation reaction of diamine and dicarboxylic acid can be used. have.

Specific examples of lactams having ternary-rings or more may include ε-caprolactam, enanthcaprolactam, α-pyrrolidone, α-piperidone, and the like. Specific examples of the polymerizable ω-amino acid may include 6-aminohexanoic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, and the like.

Specific examples of diamines may include hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, methaxylene diamine, and the like. Specific examples of dicarboxylic acids may include terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dodecane diacid, glutaric acid, and the like.

Specific examples of the polyamide used in the present invention include nylon 4, 6, 7, 8, 11, 12, 6, 6, 10, 6, 11, 6, 12, 6T, 6/6, 6, 6 /. 12, 6 / 6T, 6I / 6T, and the like.

As a material of the heat-sealing resin layer (C), usually, high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ethylene- Methacrylic acid copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl methacrylate copolymer ( EMAA), adhesive polyethylene, ionomer resins, saponified products of EVA, linear low density polyethylene (L-LDPE) or copolymers thereof. Of these compounds, preference is given to using linear low density polyethylene (L-LDPE).

Linear low density polyethylene (L-LDPE) is a copolymer of ethylene and an α-olefin having 3 to 13 carbon atoms and has an ethylene content of 86 to 99.5 mol%. L-LDPE is a medium to low density polyethylene, unlike conventional high pressure treated LDPE. Autoclaved LDPE and L-LDPE differ in that autoclaved LEPE has a multi-branched molecular structure, whereas L-LDPE has a linear molecular structure. In preparing L-LDPE, butene-1, pentene-1, hexene-1, octene-1, 4-methylpentene-1 and the like can be used as the α-olefin to be copolymerized with ethylene. The copolymerization reaction of the α-olefin and ethylene can be carried out by a low to medium pressure treatment using a so-called Ziegler-Natta catalyst.

Specific examples of commercially available products of the linear low density polyetherene (L-LDPE) described above include UNIPOL (Union Carbide), DOWLEX (Dow Chemical), SQULERE (Dupont, Canada), MARLEX (Philips), NEOZEX and ULTZEX (Mitsui Petrochemical) , NISSEKI LINILEX (Nippon Petrochemical), STAMILEX (DSM) and the like.

The adhesive resin layer may typically be composed of a modified polyolefin resin (APO). Such APO can be prepared by copolymerizing and / or graft-polymerizing a polyolefin resin composed mainly of an ethylene component and / or a propylene component with an α-, β-unsaturated carboxylic acid or a derivative thereof.

As the polyolefin resin, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-sodium acrylate copolymer Etc. can be mentioned.

Examples of α- and β-unsaturated carboxylic acids or derivatives thereof to be copolymerized with polyolefin resins include acrylic acid, methacrylic acid, methyl methacrylate, sodium acrylate, zinc acrylate, vinyl acetate, glycidyl methacrylate, and the like. . These α-, β-unsaturated carboxylic acids or derivatives thereof may be present in the molecular chain of the polyolefin resin in an amount up to 40 mol%.

Examples of α- and β-unsaturated carboxylic acids or derivatives thereof to be grafted to the polyolefin resin include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, anhydrides of these acids, esters of these acids and the like. Of these compounds used for modifying polyolefin resins, maleic anhydride is particularly preferred. The amount of these compounds grafted is 0.01 to 25% by weight, preferably 0.05 to 1.5% by weight, based on the weight of the polyolefin resin.

The graft polymerization reaction can be carried out by conventional melt-mixing of a polyolefin resin and an α-, β-unsaturated carboxylic acid or a derivative thereof at a conventional method such as a resin temperature of 150 to 300 ° C. In the graft polymerization reaction, in order to effectively carry out the reaction, an organic peroxide such as α, α'-bis-tert-butylperoxy-p-diisopropyl benzene is added to a polyolefin resin and α-, β-unsaturated carboxylic acid or a derivative thereof. It is preferred to add to the reaction mixture in an amount of 0.001 to 0.05% by weight based on the total amount of.

In the unstretched laminated film, a resin layer (A) consisting of a blend of polyethylene naphthalate resin and polyethylene terephthalate resin or composed of polybutylene terephthalate resin is disposed as the outermost layer of the packaging container, and composed of a heat sealable resin. The resin layer (C) is disposed as the innermost layer of the packaging container, and the resin layer (B) composed of a gas-blocking resin is disposed as an intermediate layer inserted between the resin layers (A) and (C). The thickness of the resin layer (A) is usually 5 to 100 m, preferably 10 to 70 m. The thickness of the resin layer (B) is usually 5 to 50 µm, preferably 10 to 30 µm. The thickness of the resin layer (C) is usually 20 to 100 m, preferably 30 to 70 m. In a preferred embodiment of the present invention, the thickness of the adhesive layer that can be inserted between adjacent resin layers is usually 2 to 30 µm, preferably 5 to 15 µm.

The packaging container according to the invention can be produced by, for example, first forming a tubular body of a laminated film by a water flow forming method of a down stream using a coextruded cylindrical die, and then heat sealing the end of the tubular body. The laminated film can be produced by the T-die method. Hot sealing can usually be carried out by a gusseting method. Co-extrusion molding and gusseting methods are well known in the art, and their suitable procedures are briefly described below.

That is, in the co-extrusion molding method, a water tank provided with an internal sizing ring is usually disposed below a cylindrical die. In addition, a guide plate and a take-up roll are continuously placed under the water bath. A plurality of raw material resins are coextruded through the cylindrical die while substantially preventing the resin from stretching. After cooling the coextruded resin through the sizing ring during cooling, the resulting tubular laminated film is passed through a guide plate and fed into a winding roll to fold and wind up the film in the form of a double film. Therefore, the laminated film obtained is almost unstretched. In a preferred embodiment, the laminated film exhibits a heat shrinkage ratio (JIS K 6734) of 5% or less in either the longitudinal direction (MD) and the transverse direction (TD).

The gusseting method is a process of folding and sealing the distal end of the tubular body of the film. In a conventional gusseting method, a tubular film is formed in a rectangle at the open end, and a pair of opposing walls is folded inward from almost the centerline of each wall. Fold another pair of walls and overlap them in line over the folded opposite wall to form a gusset between them. The folded tubular film thus obtained is heat sealed along the end of the caster using a heat sealing rod.

The packaging container according to the present invention can be suitably used, for example, a food packaging container for preparing ham and sausage, a beverage packaging container filled with natural water, and the like. In particular, since the outermost layer of the packaging container is made of a specific polyester resin, the packaging container can exhibit excellent label adhesion even immediately after taking out from the retainer. It is believed that this technical advantage of the packaging container according to the invention is provided by the outermost layer consisting of a resin having a very high moisture release or removal. However, as described in the comparative examples below, this technical advantage of the packaging container according to the present invention cannot be achieved using, for example, a PET resin or a PEN resin similar to a PBT resin. Therefore, the effect of the present invention achieved by using a specific compounding resin or PBT resin is a very unexpected result.

In particular, when the outermost layer of the packaging container according to the invention is composed of a polyester resin containing at least 70 mol% of polybutylene terephthalate-forming units, the laminated film itself exhibits excellent anti-curl properties. Can be. Specifically, since the outermost layer consists of resins other than the polyester resin mentioned above, curling is easy to generate | occur | produce in these open ends, it cannot fill a raw material suitably. On the other hand, the packaging container according to the present invention, in which the outermost layer is composed of a polyester resin containing 70 mol% or more of polybutylene terephthalate units, does not have these disadvantages exhibited in conventional packaging containers.

Example

Although the present invention will be described in more detail with reference to the following examples, the present invention is not limited to these examples and various modifications are possible within the scope of the present invention.

Example 1:

Laminated film with multilayer structure: 5 layers of PBT layer (8 μm) / APO layer (6 μm) / NY (nylon 6) layer (16 μm) / APO layer (6 μm) / L-LDPE layer (44 μm) It formed into tubular shape by the water-cooling shaping | molding method of the down stream using a coextrusion cylindrical die. In preparing the laminated film, polymethyl methacrylate (PMMA) particles having an average particle diameter of 6 mu m as an anti-sticking agent were added to the raw material PBT resin in an amount of 2,000 ppm. The extrusion temperature was 240 degreeC, the water cooling temperature was 28 degreeC, and the winding speed of the film was 15 m / min. The tubular laminated film thus obtained was cut to a predetermined length. The cut tubular film was subjected to a gusseting process in which the heat-sealed linearly was sealed along one of their columnar ends, thereby obtaining a gusseted container having an outermost layer composed of PBT and an innermost layer composed of L-LDPE.

After filling the vessel cooked with the raw ham raw material, it was placed in the retainer to heat-process the raw material to obtain a rectangular ham having a quadrilateral area of 8 cm x 8 cm and a total length of 35 cm at their nearly transverse centers. The label adhesion, anti-sticking properties, pinhole resistance and curl resistance of this packaged ham product were evaluated by the following method. The results are shown in Table 2.

(1) label adhesion:

Immediately after taking out from the retainer, a label was applied on the packaging container surface of the ham product and measured for their peel strength (g / 15 mm).

(2) pinhole resistance:

Ten boxes of packaging containers (10 containers per box) were subjected to refrigerated transportation testing at -20 ° C (by traversing Shiko-ku region). The pinhole resistance of the packaging container was evaluated by measuring the number of containers torn in transit.

(3) anti-sticking properties:

To measure their sliding properties, one of the two packaged ham products with dried surfaces was stacked on the other. This measurement was carried out using a tensile tester, and the measured sliding characteristics were expressed in grams. The smaller the number of grams, the higher the slipping property and the better the anti-sticking property.

(4) corrosion resistance:

Curing was visually observed at the open end of each caster vessel.

Examples 2 and 3 and Comparative Examples 1 to 3:

Except that the kind of resin used for the outermost layer was changed as shown in Table 1, by carrying out the same procedure as defined in Example 1, a gusseted container was obtained and the ham product was then packaged. The copolymerized PBT resin used in Example 3 had a melting point of 222 占 폚 and contained 2.5 mol% of polytetramethylene oxide glycol having a number average molecular weight of 1,000 as a copolymerization component. For reference, in the same manner as in Example 1, the raw material of the outermost layer was mixed with 2,000 ppm of PMMA particles having an average particle diameter of 6 µm. The label adhesion, anti-sticking properties and pinhole resistance of the thus obtained packaged ham product were evaluated in the same manner as in Example 1. The results are shown in Table 2.

TABLE 1

TABLE 2

The packaging container according to the present invention exhibited excellent label adhesion, anti-sticking properties, pinhole resistance and curl resistance.

Claims (4)

(A) Polyester resin layer containing the anti-sticking agent which consists of 70 mol% or more of polybutylene terephthalate-forming units and an organic particle as an outermost layer; (B) a gas-blocking resin layer; And (C) A packaging container comprising a heat-sealed unstretched laminated film comprising a heat-sealable resin layer as the innermost layer, wherein the resin layers (A) to (C) are arranged in the above order. (A) Copolymer containing, as outermost layer, copolymer component units comprising polytetramethylene oxide glycol having polybutylene terephthalate-forming units having a number average molecular weight of 70 to 99 mol% and 300 to 6,000. A polyester resin layer composed of polybutylene terephthalate resin; (B) a gas-blocking resin layer; And (C) A packaging container comprising a heat-sealed unstretched laminated film comprising a heat-sealable resin layer as the innermost layer, wherein the resin layers (A) to (C) are arranged in the above order. The packaging container of Claim 2 in which the said resin layer (A) contains the anti-sticking agent comprised from organic particle | grains. The packaging container according to claim 1 or 2, which is used for food packaging.