JP4089024B2 - Food packaging bags - Google Patents

Description

【００３９】
【表２】

【００４０】
【発明の効果】
以上説明した本発明によれば、ラベル接着強度および耐ピンホール性に優れた食品包装袋が提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a food packaging bag, and more particularly to a food packaging bag suitably used for producing ham, sausage or the like.
[0002]
[Prior art]
In general, ham and sausage are manufactured by filling a bag made of shrink film with a raw material and then heat-treating it in a retainer. Prior to shipment, a printed label is attached to the bag surface. Since the adhesive strength of the label is affected by the moisture on the label attachment surface, the bag surface of the product taken out from the retainer may be sufficiently drained so that it does not need to be dried before label attachment. desirable. Also, excellent pinhole resistance is required during transportation.
[0003]
[Problems to be solved by the invention]
This invention is made | formed in view of the said situation, The objective is to provide the food packaging bag excellent in label adhesive strength and pinhole resistance.
[0004]
[Means for Solving the Problems]
That is, the gist of the present invention is that an end portion of an unstretched laminated film cylindrical body is formed in a rectangular shape, two opposing sides are valley-folded from their approximate center, and the other two sides are overlapped with each other. A food packaging container for heat treatment in a retainer that is heat-sealed by a linear heat-seal bar along a portion, wherein the laminated film includes at least a copolymerized polybutylene terephthalate resin layer ( A) A multilayer structure in which a gas barrier resin layer (B) and a heat sealable resin layer (C) disposed in the innermost layer are sequentially laminated. In the copolymer polybutylene terephthalate resin, a polybutylene terephthalate unit Is derived from polytetramethylene oxide glycol having a number average molecular weight of 300 to 6000, and the remaining copolymer component unit is 85 to 99 mol%. Unit der that is, the resin layer (A) consists in a food packaging bag is characterized that you have to contain an anti-blocking agent composed of an organic particulate.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. The food packaging bag of the present invention is constituted by heat-sealing an unstretched laminated film. The unstretched laminated film includes at least a copolymerized polybutylene terephthalate (PBT) resin layer (A) disposed in the outermost layer, a gas barrier resin layer (B), and a heat sealable resin disposed in the innermost layer. It has a multilayer structure in which the layers (C) are sequentially laminated. And in the preferable aspect of this invention, an adhesive resin layer is arrange | positioned between said each interlayer.
[0006]
In the copolymerization PBT resin layer (A), the proportion of PBT units derived from terephthalic acid and butylene glycol are 8 5 to 99 mol%, a unit which residual is derived from the copolymerization component. The copolymer PBT resin preferably has a melting point in the range of 200 to 223 ° C. Incidentally, the melting point of homo PBT resin is 225 ° C.
[0007]
In the present invention, as the copolymerization component of the copolymer PBT resin layer (A), is used polytetramethylene oxide glycol, the number average molecular weight is 3 00-6000, is good Mashiku in the range of 500-2000 . The copolymerized PBT resin satisfying such conditions gives the film flexibility without impairing the heat resistance, and has excellent pinhole resistance exceeding that of the homo PBT resin because of excellent low-temperature strength and elongation.
[0008]
Copolymerized PBT resin layer (A), from the viewpoint of blocking resistance during lamination storage food packaging bags, Ru is contained an anti-blocking agent comprising al or organic fine particles.
[0009]
Examples of the anti-blocking agent composed of the above organic fine particles include, for example, polystyrene, polyethylene, polyamide, polyester, polyacrylic acid ester, polymethacrylic acid ester, epoxy resin, polyvinyl acetate, polyvinyl chloride and the like alone or as a copolymer. also contain a crosslinking agent consisting of include good fine.
[0010]
The average particle size of each antiblocking agent is usually about 1 to 10 μm, and the amount used is usually 100 to 10,000 ppm, preferably 1,000 to 5,000 ppm, based on the resin. In the present invention, especially, fine particles of polyacrylic acid esters or polymethacrylic acid esters are preferably used.
[0011]
The gas barrier resin layer (B) is selected from the group of polyamide (PA), saponified ethylene-vinyl acetate copolymer (EVOH), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polycarbonate (PC). It is composed of any resin. Among these, polyamide (PA) or ethylene-vinyl acetate copolymer saponified product (EVOH) is preferable, and polyamide (PA) is particularly preferable.
[0012]
In the present invention, polyamides obtained by polycondensation of (1) 3-membered or more lactams, (2) polymerizable ω-amino acids, and (3) diamine and dicarboxylic acid polyamide raw materials can be used.
[0013]
Specific examples of the lactam having 3 or more rings include ε-caprolactam, enantolactam, α-pyrrolidone, α-piperidone, and the like, and specific examples of the polymerizable ω-amino acid include 6-amino Examples include hexanoic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 9-aminononanoic acid.
[0014]
Specific examples of the diamine include hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, and metaxylylene diamine. Specific examples of the dicarboxylic acid include terephthalic acid and isophthalic acid. , Adipic acid, sebacic acid, dodecanedioic acid, glutaric acid and the like.
[0015]
Specific examples of the polyamide used in the present invention include nylon 4, 6, 7, 8, 11, 12, 6 · 6, 6 · 10, 6 · 11, 6 · 12, 6T, 6/6 · 6, 6 / 12, 6 / 6T, 6I / 6T, and the like.
[0016]
The heat-sealable resin layer (C) is usually made of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ethylene- Methacrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EAA), ethylene-ethyl methacrylate copolymer ( EMAA), adhesive polyethylene, ionomer resin, EVA saponified product, linear low density polyethylene (L-LDPE) or a copolymer thereof is used. Among these, linear low density polyethylene (L-LDPE) is preferable.
[0017]
Linear low density polyethylene (L-LDPE) is a copolymer of ethylene and an α-olefin having 3 to 13 carbon atoms (ethylene content: 86 to 99.5 mol%), and is produced by a conventional high pressure method. It is a low to medium density polyethylene different from the LDPE produced. The structural difference between the high pressure method LDPE and LLDPE is that the former has a multi-branched molecular structure and the latter has a linear molecular structure. Examples of the α-olefin copolymerized with ethylene in the production of LLDPE include butene-1, pentene-1, hexene-1, octene-1, 4-methylpentene-1. These copolymers are carried out by a low-medium pressure method using a so-called Ziegler-Natta type catalyst.
[0018]
Specific examples of the above LLDPE can be shown by trade names: Unipol (UCC), Dowlex (Dow Chemical), Screer (DuPont Canada), Marlex (Philips), Neox and Ultzets (Mitsui Petrochemical), Japan Stone Linilex (Nippon Petrochemical Co., Ltd.), Stamilex (DSM Corp.), etc. are mentioned.
[0019]
The adhesive resin layer is usually composed of a modified polyolefin resin (APO). Such APO is produced by copolymerizing and / or graft-polymerizing an α, β unsaturated carboxylic acid or a derivative thereof to a polyolefin resin mainly composed of an ethylene component and / or a propylene component.
[0020]
Examples of the polyolefin resin include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, and ethylene-ethylacrylic acid. Examples thereof include a copolymer and an ethylene-sodium acrylate copolymer.
[0021]
Examples of the α, β-unsaturated carboxylic acid or derivative thereof to be copolymerized include acrylic acid, methacrylic acid, methyl methacrylic acid, sodium acrylate, zinc acrylate, vinyl acetate, glycidyl methacrylate, and the like. It is contained in the range within 40 mol%. Examples of the copolymer-modified polyolefin resin include an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene-ethylacrylic acid copolymer, and an ethylene-sodium acrylate copolymer.
[0022]
Examples of the grafted α, β-unsaturated carboxylic acid or derivative thereof include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, acid anhydrides thereof, and esters of these acids. Is mentioned. Of these modifying compounds, maleic anhydride is particularly preferred. The graft amount is selected from the range of 0.01 to 25% by weight, preferably 0.05 to 1.5% by weight, based on the polyolefin resin.
[0023]
The grafting reaction is usually performed by melt-mixing a polyolefin resin and an α, β-unsaturated carboxylic acid or a derivative thereof at a resin temperature of 150 to 300 ° C. according to a conventional method. In the grafting reaction, 0.001 to 0.05% by weight of an organic peroxide such as α, α'-bis-t-butylperoxy-p-diisopropylbenzene is blended in order to carry out the reaction efficiently. Is good.
[0024]
In the non-laminated film, the copolymerized PBT resin layer (A) is disposed in the outermost layer, the heat sealable resin layer (C) is disposed in the innermost layer, and the gas barrier resin layer (B) is disposed in the middle thereof. Is done. The thickness of the (A) layer is usually 5 to 100 μm, preferably 10 to 70 μm, the thickness of the (B) layer is usually 5 to 50 μm, preferably 10 to 30 μm, and the thickness of the (C) layer is usually The thickness is 20 to 100 μm, preferably 30 to 70 μm. In the preferred embodiment, the thickness of the adhesive resin layer disposed between the layers is usually 2 to 30 μm, preferably 5 to 15 μm.
[0025]
The food packaging bag of the present invention is manufactured, for example, by manufacturing a cylindrical body of a laminated film by a downward water-cooling molding method using a coextrusion annular die and then heat-sealing the end of the cylindrical body. The laminated film may be manufactured by a T-die method. And said heat sealing is normally performed as a gusset process. The co-extrusion method and gusset processing are both known techniques per se, and the outline of preferred embodiments thereof is as follows.
[0026]
That is, in the above-mentioned coextrusion molding method, usually, a water tank having a size ring inside is disposed below the annular die, and an an inner plate and a winding roll are sequentially disposed below the water tank. And then co-extruding a plurality of types of resin from the annular die so that substantially no stretching occurs, and after passing through the size ring for cooling, the cylinder of the laminated film is made safe. This is a method in which the film is supplied to a take-up roll through an inner plate, folded, and taken up as a double film. Therefore, the obtained laminated film is substantially an unstretched film, and in the preferred embodiment, the heat shrinkage (JIS K 6734) in the length direction (MD) and the width direction (TD) are both 5% or less. is there.
[0027]
The gusset processing is a processing method in which the end of the cylindrical body is folded and sealed, and in the case of normal gusset processing, the end of the cylindrical body is formed in a rectangular shape, and the two opposite sides are formed from their approximate center. The valley is folded, and the other two sides are overlapped with each other and heat sealed by a linear heat seal bar along the end.
[0028]
The food packaging bag of the present invention is preferably used when producing ham, sausage, etc., for example, and in particular, by forming the outermost layer with a copolymerized PBT resin, the label adhesive strength immediately after taking out from the retainer. It has the feature of being excellent. Such characteristics are presumed to be based on the reason that the water drainage of the resin constituting the outermost layer is extremely good. For example, as shown in a comparative example described later, for example, the same type of PET resin or PEN as the PBT resin The fact that it is not achieved with a resin and is achieved with a specific polyester resin is a surprising fact.
[0029]
In particular, the food packaging bag of the present invention in which the outermost layer is composed of a copolymerized PBT resin has a feature that the curl resistance of the laminated film itself is also excellent. In other words, food packaging bags whose outermost layer is made of a resin other than PBT resin may curl the open end of the gusseted bag and cause troubles when filling the raw material. It does not occur in food packaging bags made of PBT resin.
[0030]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.
[0031]
Example 1
Layer structure of copolymerized PBT (8 μm) / APO (6 μm) / NY: nylon 6 (16 μm) / APO (6 μm) / L-LDPE (44 μm) by downward water-cooling molding using a five-layer coextrusion annular die A cylindrical body of a laminated film having the following was manufactured. The copolymer PBT has a melting point of 222 ° C., a copolymer component of polytetramethylene oxide glycol having a number average molecular weight of 1000, a content of 2.5 mol%, and as an anti-procking agent. 2,000 ppm of polymethyl methacrylate (PMMA) fine particles having an average particle diameter of 6 μm were blended and used. The extrusion temperature was 240 ° C., the water cooling temperature was 28 ° C., and the winding speed was 15 m / min. It was. The obtained cylindrical body is slit to a predetermined length, and gusset processing with linear heat sealing along the end portion is performed at one end portion thereof to obtain a gusset bag in which the outermost layer is PBT and the innermost layer is L-LDPE. It was.
[0032]
After filling the above-mentioned gusset bag with ham raw material cooked in advance, the hamset was set in a retainer and heat-treated to produce a rectangular ham having a length and width of 8 cm in the center in the longitudinal direction and a total length of 35 cm. About the obtained ham product, label adhesive strength, blocking resistance, pinhole resistance, and curling property were evaluated by the following methods (1) to (4), and the results are shown in Table 2.
[0033]
(1) Label adhesion strength:
A label was affixed to the surface of a bag of ham product immediately after removal from the retainer, and the peel strength (g / 15 mm) was measured.
[0034]
(2) Pinhole resistance:
Ten cases (10 bags / case) were subjected to a refrigerated transport test (-20 yen in Shikoku) at -20 ° C., and the number of broken bags at the time of transfer was evaluated.
[0035]
(3) Blocking resistance:
Two ham products whose surfaces were dried were overlapped to measure the slipperiness. A tensile tester was used for the measurement, and the slipperiness was expressed in g. The smaller the g number, the better the slipperiness and the better the blocking resistance.
[0036]
(4) Curl property:
The state of curling at the open end of the gusset bag was visually observed.
[0037]
Example 2 and Comparative Examples 1-3
A ham product was manufactured after obtaining a gusset bag in the same manner as in Example 1 except that the type of the outermost resin was changed as shown in Table 1. The outermost raw material resin was mixed with 3000 ppm of PMMA fine particles having an average particle diameter of 6 μm in the same manner as in Example 1. About the obtained ham product, label adhesive strength, blocking resistance, and pinhole resistance were evaluated, and the results are shown in Table 2.
[0038]
[Table 1]

[0039]
[Table 2]

[0040]
【The invention's effect】
According to the present invention described above, a food packaging bag excellent in label adhesive strength and pinhole resistance is provided.

Claims (1)

The end of the unstretched laminated film cylinder is formed in a square shape, and the two opposite sides are valley-folded from their approximate center, and the other two sides are overlapped with this to form a linear heat along the end. A food packaging container for heat treatment in a retainer that is heat-sealed by a seal bar, wherein the laminated film includes at least a copolymerized polybutylene terephthalate resin layer (A) disposed in the outermost layer, a gas barrier resin layer ( B), having a multilayer structure in which heat-sealable resin layers (C) arranged in the innermost layer are sequentially laminated, and in the above-mentioned copolymer polybutylene terephthalate resin, the proportion of polybutylene terephthalate units is 85 to 99 mol%. , and the unit der the remainder copolymer component units derived from polytetramethylene oxide glycol having a number average molecular weight 300 to 6,000 is, the resin layer ( ) Food packaging bag characterized that you have to contain an anti-blocking agent composed of an organic particulate.