JP2711304C - - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-shrinkable multilayer film for sausage and a sausage package using the heat-shrinkable multilayer film for sausage. Using a heat-shrinkable multilayer film for sausage, which is excellent in food resistance, transparency, tension, pinhole resistance, package deformation resistance, etc., and can be suitably used for shrinkage packaging of sausage. The present invention relates to a sausage package. [Conventional technology and problems] Processed meat and processed fish meat, such as ham and sausage, are packaged using an oxygen gas barrier film from the viewpoint of preservation, and then heat-sterilized. Conventionally,
The sterilization temperature was 70-90 ° C, but it kept appropriate tension and transparency even in high-temperature processing near 120 ° C due to the use of sterilizer, regulation of the amount used, and the requirement of short-time processing. However, development of a heat-shrinkable film free from appearance defects such as wrinkles and deformations is desired. Conventional multilayer films for shrink wrapping of retort foods include, for example, shrink multilayer films made of nylon / polyolefin (JP-A-59-212,261, JP-A-56-136,365, JP-B-60-35257), Nylon / polypropylene multilayer films (JP-A-51-64,583, JP-B-61-23,110) are known, but the above-mentioned ones are suitable for pasteurization treatment at 80 to 90 ° C ( The heat shrinkage is 20% or more.), And since the heat treatment temperature is 90 ° C. or less, a polyethylene resin is used as the polyolefin from the viewpoint of heat sealing. However, when a retort treatment is performed at 120 ° C. using such a conventional film, the polyolefin is whitened, the transparency is deteriorated, and there is a problem that the sealing property of the sealing portion is uneasy. On the other hand, in the case of the above-mentioned multilayer film, the degree of stretching of the film is unknown, and when used for retort packaging, particularly when subjected to a high temperature treatment of 120 ° C., the tightness of the multilayer film, the crush-resistant bag However, there is a problem that the resistance and the deformation resistance cannot be secured. Further, with respect to the above films and films, there is no description of shrinkage when heated to 120 ° C., and both films are developed for low-temperature retort treatment. The present invention has been made based on the above circumstances. An object of the first invention of the present application is that even when a high-temperature retort treatment of 120 ° C. is performed,
Sausage packaging that exhibits appropriate shrinkage, excels in tightness and transparency, has no appearance deformation, and has excellent basic properties for sausage packaging, such as oxygen gas barrier properties and moisture permeability resistance, and is particularly suitable for high-temperature retort processing. It is an object of the present invention to provide a heat-shrinkable multilayer film for sausage, and a sausage package using the heat-shrinkable multilayer film for sausage having excellent characteristics as described above. Is to provide the body. [Means for Achieving the Object] As a result of intensive studies conducted by the present inventors to develop a heat-shrinkable multilayer film for food shrink wrapping suitable for high-temperature retort treatment, at least a specific resin, that is, Heat shrinkage comprising a polyamide resin having a thickness of 5 to 50 μm and a polypropylene resin having a transparency of 5 to 100 μm while maintaining transparency in a heat treatment at 120 ° C. and having a specific heat shrinkage Even when the multi-layer film is subjected to a high temperature retort treatment at 120 ° C, it retains appropriate tension and transparency, does not have poor appearance or deformation, and is used for sausage packaging such as oxygen gas barrier property and moisture permeability resistance. The inventors have found that the film is a multilayer film having excellent basic characteristics, and based on this finding, completed the first invention (the invention of claim 1). It has been found that a food package using the heat-shrinkable multilayer film having the above is a practically excellent sausage package suitable for a retort treatment at a high temperature of 120 ° C., and the second invention (claim 2) Invention) has been completed. That is, the configuration of the first invention of the present application maintains transparency at least in the polyamide resin layer (A) having a thickness of 5 to 50 μm and heat treatment at 120 ° C., and has a thickness of 5 to 100 μm. It consists of a polypropylene resin layer (B),
A heat-shrinkable multilayer film for sausage characterized in that the heat-shrinkage ratio at 0 ° C. is 5 to 30%.
It is composed of a polyamide resin layer (A) having a thickness of 50 μm and a polypropylene resin layer (B) having a thickness of 5 to 100 μm while maintaining transparency in a heat treatment at 120 ° C. A sausage package characterized by using a heat-shrinkable multilayer film of 30%. The heat-shrinkable multilayer film for sausages (hereinafter simply referred to as a heat-shrinkable multilayer film) in the first invention and the second invention of the present application will be described in detail with reference to the drawings. FIG. 1 is a sectional view conceptually showing an example of a layer structure of a heat-shrinkable multilayer film according to the first invention and the second invention. In the figure, (B) shows a polypropylene resin layer, and (A) shows a polyamide resin layer. The (A) layer and the (B) layer are usually bonded using an adhesive or an adhesive resin,
They can be laminated and integrated. Although FIG. 1 shows an example in which the adhesive layer (D) is used between the (A) layer and the (B) layer, as described later, the (A) layer and (B) The integration with the layer may be performed by laminating using a laminating adhesive. As described above, the heat-shrinkable multilayer film of the first invention of the present application comprises at least the polypropylene-based resin layer (B) and the polyamide-based resin layer (A) as raw materials. ) Layer and (B) layer may be further laminated by interposing (E) an oxygen gas barrier resin layer therebetween, and may be integrated. Further, (C)
A heat resistant resin layer may be laminated and integrated. As described above, by using the layer (E), the oxygen gas barrier property of the heat-shrinkable multilayer film can be further improved, and by using the layer (C), the moisture-proof property and heat resistance of the multilayer film can be improved. It can be further improved. As the polyamide resin used as the (A) layer, known resins such as nylon-6, nylon-66, nylon-11, nylon-12, nylon-610, nylon-6-12, nylon-6-6, nylon −6-12-66 and the like. These may be used alone or in combination of two or more of them in the form of a composition or a multilayer structure. The number average molecular weight of the polyamide resin is usually 10,000 to 1
It is in the range of 00,000. Further, as the polyamide resin, 230 ° C, 1
00 seconds melt viscosity measured under measurement conditions of a shear rate of ^-1, preferably those in the range of 5 × 10 ^-3 ~50 × 10 ^-3 poise, 10 × 10 ^-3 ~
Those in the range of 20 × 10 ⁻³ are particularly preferred. If the ratio is outside the above range, workability may be reduced. The layer (A) is usually sufficient to be used as a single layer itself,
It is also possible to use a multilayer structure having more than two layers. As the polypropylene resin used as the layer (B), known resins, for example, H-PP (polypropylene homopolymer), R-PP (random copolymer of propylene and other olefins), B-PP ( Block copolymers of propylene and other olefins) or mixtures or blends thereof, or these polypropylene resins and other resins or elastomers (eg, EPR,
And low-crystalline resins such as ethylene-butene-1 copolymer, polyethylene, and linear low-density polyethylene. The other olefin in the propylene copolymer includes, for example,
Examples thereof include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. When other components are added to the polypropylene resin for use, it is desirable that the added components be added within a range that does not cause whitening and a decrease in transparency during the retort treatment at 120 ° C. As the heat-resistant resin of the layer (C) optionally used, for example, a heat-resistant polyester resin, the above-mentioned polypropylene resin, or the like can be suitably used. As the oxygen gas barrier resin of the (E) layer optionally used, for example,
Polyvinylidene chloride, polyvinyl alcohol and the like can be suitably used. The oxygen gas barrier resin layer may be bonded and laminated and integrated using the same adhesive or adhesive resin as in the above (D), or may be co-extruded with the polyamide resin of the layer (A). It may be provided by stretching. As the adhesive used for laminating and unifying each layer such as the (A) layer and the (B) layer, those used as ordinary multilayer films for retort food packaging, such as a laminate adhesive, may be suitably used. As the adhesive resin, for example, maleic anhydride-modified polypropylene or the like can be preferably used. The heat-shrinkable multilayer film according to the first and second aspects of the present invention has a temperature of 120 ° C.
Is in the range of 5 to 30%, preferably in the range of 7 to 20%. The control of the shrinkage ratio within the above range is performed by the resin film used for each layer, or the manufacturing conditions of the lamination and integration of each film, that is, the production process of the multilayer film, for example, the stretching ratio when forming a film or a multilayer film or the like. Stretching conditions such as stretching temperature, heat treatment conditions of stretched film or stretched multilayer film, ie, tension, relaxation,
It can be carried out by adjusting the temperature (for example, 50 to 230 ° C.), the processing time, and the like. When the shrinkage ratio is less than 5%, it is used for sausage packaging,
When a high-temperature retort sterilization treatment in the vicinity is performed, the shrinkage is insufficient, the tightness is poor, the appearance of the sausage package is poor, and the texture is poor. On the other hand, when the shrinkage rate exceeds 30%, when used in a sausage package as described above, the end of the film is deformed, or unnecessary force is applied to the sealing portion, and it is insufficient to secure the sealing performance. Or pinholes may occur. The shrinkage rate is determined within an appropriate range based on the type of the packaged object, the filling rate, and the like. The layer thickness of the polyamide resin layer (A) used is 5 to 50 μm, preferably 5 to 50 μm.
-30 μm, more preferably 8-20 μm. When the film thickness is less than 5 μm, the gas barrier property is low, and the pinhole resistance may be reduced. On the other hand, when the film thickness exceeds 50 μm, excessive physical properties may occur. The thick film of the polypropylene resin layer (B) has a thickness of 5 to 100 μm, preferably 5 to 60 μm. If the film thickness is less than 5 μm, the sealing resistance may be reduced and the sealing property may be insufficient. On the other hand, if the film thickness exceeds 100 μm, excess physical properties may occur. The thickness of the adhesive layer to be used is usually preferably in the range of about 0.5 to 20 μm. As the thickness of the heat-shrinkable multilayer film in the first invention and the second invention,
It is preferable that the thickness is usually in the range of 10 to 200 μm, generally in the range of 20 to 120 μm. The method for producing the heat-shrinkable multilayer film in the first invention and the second invention of the present application is not particularly limited, and examples thereof include the following method. (A) a biaxially stretched film of a polyamide resin having a predetermined shrinkability as a layer,
(B) A non-stretched or stretched film of a polypropylene-based resin as a layer and a laminating adhesive as an adhesive layer, for example, bonded by a lamination method, laminated and integrated, and a desired heat-shrinkable multilayer film having a predetermined shrinkage ratio And how. (A) layer of polyamide resin and adhesive layer (D) and (B) adhesive resin-containing polypropylene resin such as maleic anhydride-modified polypropylene resin as layer, or (
A) a polyamide resin as the layer, an adhesive resin such as maleic anhydride-modified polypropylene as the adhesive layer (D), and a polypropylene resin as the (B) layer are co-extruded in multiple layers to form an unstretched multilayer film. A method in which a heat-shrinkable multilayer film is formed by controlling the shrinkage by performing heat treatment at an appropriate temperature, for example, within a temperature range of 50 to 230 ° C. The stretched polyamide resin film used above can be obtained, for example, by forming the film into a film or a sheet using the above-mentioned polyamide resin, and then stretching the film. Examples of the above laminating method include methods such as dry lamination, non-solvent lamination, and extrusion. In addition, as a manufacturing method of the heat-shrinkable multilayer film having the (C) layer, for example, in the above method and the above method, the heat-resistant resin used as the (C) layer or a stretched film thereof is provided at the same time as the lamination and integration. Alternatively, a method in which the layers are sequentially laminated and provided can be suitably applied. When a heat-shrinkable multilayer film having the (E) layer is obtained, for example, in the above-mentioned method, the (E) layer may be formed by using an oxygen gas barrier resin as a single film or by coextrusion with a polyamide resin in advance. A method of laminating in the same manner using a two-layer film formed as described above, and in the above-mentioned method, similarly forming a co-extruded film, stretching, and heat-treating using a gas barrier resin as the (E) layer. The method can be suitably applied. The heat-shrinkable multilayer film of the first invention of the present application obtained as described above has appropriate shrinkage even when subjected to a high-temperature retort treatment of, for example, 120 ° C., has excellent tightness with contents, and has wrinkles. No defective appearance such as deformation, deformation, etc., excellent transparency, good sealability, no pinholes between film part and seal layer, and food packaging such as oxygen gas barrier property, moisture resistance, food resistance etc. Heat-shrinkable multilayer film with excellent basic properties as a film for use. Shrink packaging of retort foods by forming into various shapes according to the shape of sausage to be used, especially packaging under high temperature retort processing at around 120 ° C. It is suitably used as a heat-shrinkable packaging film for sausages. The sausage package of the second invention of the present application is a sausage package obtained by shrink-wrapping sausage using the heat-shrinkable multilayer film of the first invention of the present application. The type and shape of the sausage are not particularly limited, and edible meats such as solid cooked meats and the like can be cited as preferable ones. The sausage package can be produced according to a known method. For example, the heat-shrinkable multilayer film of the first invention of the present application is formed into a shape suitable for the shape of the food to be used as the content. Then, the sausage is molded into a tube or a tube, and the sausage is sealed and packaged as a content, then retorted at a predetermined temperature, and the used multi-layer film is heat-shrinked to provide excellent sausage with tightness and adhesion. And a method for obtaining a shrink-wrapped product. The sealing method in this case may be welding using an ultrasonic seal or the like, or caulking with metal, so-called rocket packaging. The temperature of the retort treatment is usually 100 to 140 ° C, preferably 110 to 140 ° C.
130 ° C. is appropriate, and particularly high-temperature processing at around 120 ° C. can be applied without any problem. The sausage package of the second invention is a heat-shrinkable multilayer film of the specific heat-shrinkable multilayer film of the first invention of the present application, that is, a heat-shrinkable multilayer film having excellent retort food shrinkage packaging characteristics suitable for high-temperature retort treatment at around 120 ° C. , Especially 12
Even when subjected to a high-temperature retort treatment at about 0 ° C., it has high strength, has good tightness with the contents, has excellent transparency of the packaging film, and has no appearance defect or deformation,
In addition, it has excellent oxygen gas barrier properties, moisture permeability resistance, etc., and also has excellent adhesiveness of the seal part, so there is no pinhole between the seals as well as the film part,
It is a practically remarkably excellent sausage package that is not restricted by the selection of food preservative additives such as a bactericide and can greatly shorten the retort bactericidal treatment time. [Examples] (Examples 1 to 6 and Comparative Example 1) Production Example of Biaxially Stretched Polyamide Film Nylon-6 is melt-kneaded, then extruded from a downward annular die, and solidified by water cooling.
A tubular film was obtained. The obtained tubular film was stretched about three times in the length direction and the width direction using a tubular biaxial stretching apparatus, and then 207 ° C. (Example 1), 202 ° C. (Example 2), 197 ° C. (Example 3) 189 ° C. (Example 4), 1
At each of the conditions of 80 ° C. (Example 5), 192 ° C. (Example 6), and 221 ° C. (Comparative Example 1), each film is shrunk by holding both ends with clips in a tenter heat treatment machine and heat-treating each film. Biaxially stretched polyamide films having different thicknesses of 25 μm (Examples 1 to 5), 15 μm (Example 6) and 25 μm (Comparative Example 1) were obtained. Production Example of Heat Shrinkable Multilayer Film Each of the biaxially stretched polyamide films obtained above and a polypropylene film having a thickness of 40 μm were laminated using a polyurethane adhesive to obtain a heat shrinkable multilayer film. Table 1 shows the shrinkage ratio of each of the obtained multilayer films when heated at 120 ° C. (30 minutes). Each of the heat-shrinkable multilayer films obtained above in the production example and evaluation of the sausage package were bent with the polypropylene layer inside and the ends of the polypropylene layer were faced to each other, and sealed by using ultrasonic waves. A cylindrical film having an inner diameter of 35 mm was obtained. A sausage package (150 mm length) was obtained in which sausage was filled in each cylindrical film and the opening end was sealed using ultrasonic waves. Next, heat sterilization treatment (retort treatment) was performed at 120 ° C. for 30 minutes. Table 1 shows the evaluation results. After the retort treatment, no decrease in the transparency of the film was observed in any case. [Table 1] * RH: Humidity [Effect of the Invention] The heat-shrinkable multilayer film of the invention according to claim 1 is made of a specific resin, that is, a polyamide resin layer and a polypropylene resin, and has a specific range of shrinkage.
When used for shrink-sealing packaging of retort foods, etc., even when subjected to high-temperature retort treatment at around 120 ° C., it is suitable for tightness or strength with the contents, and has no appearance defects such as wrinkles and deformation, and is transparent. Heat-shrinkable multi-layer film with high resistance, good sealability, no pinholes between film part and seal layer, excellent oxygen gas barrier properties, heat resistance, etc., and also excellent food resistance It is. That is, according to the first aspect of the present invention, it is possible to provide a heat-shrinkable multilayer film having excellent characteristics as the above-described shrink-bonded packaging material for sausage. According to the second aspect of the present invention, since the heat-shrinkable multilayer film having the excellent characteristics of the first aspect is used as a packaging material, the food contents can be obtained even when a high-temperature retort treatment at about 120 ° C. is performed. Tightness is suitable, there are no appearance defects such as wrinkles, deformation, etc., and the packaging film is excellent in transparency, has good sealing properties, does not generate pinholes between the film portion and the sealing layer, and has oxygen gas barrier properties, A sausage package excellent in moisture resistance, food resistance and the like can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view conceptually showing an example of the layer constitution of the heat-shrinkable multilayer film of the present invention. A: polyamide resin layer, B: polypropylene resin layer, (C): heat resistant resin layer, (E): oxygen gas barrier improving resin layer, (D): adhesive layer .

Claims (1)

Claims (1) At least a polyamide resin layer (A) having a thickness of 5 to 50 μm and 1
It is made of a polypropylene-based resin layer (B) having a thickness of 5 to 100 μm while maintaining transparency in a heat treatment at 20 ° C., and a heat shrinkage at 120 ° C. of 5 to 30%.
A heat-shrinkable multilayer film for sausage characterized by the following. (2) At least a polyamide resin layer (A) having a thickness of 5 to 50 μm and 1
It is made of a polypropylene-based resin layer (B) having a thickness of 5 to 100 μm while maintaining transparency in a heat treatment at 20 ° C., and a heat shrinkage at 120 ° C. of 5 to 30%.
A sausage package characterized by using the heat-shrinkable multilayer film as described above.