JPS6112825B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to packaging materials that are suitable for packaging foods such as cheese and yokan, which are filled in a heated molten state and then molded and solidified. Moreover, the present invention relates to a packaging material having a resin layer that has excellent adhesion to foods, has excellent releasability to foods after cooling and solidification, and can be easily cut with a kitchen knife or the like. The present invention also relates to a packaging material made of a resin whose resin layer can be easily formed by extrusion coating. Generally, most processed cheeses, such as home-use carton stuffed cheese weighing about 150 g to 400 g, are heated and molten and filled with packaging materials. As shown in FIG. 1, cheese is closely packaged in a cheese packaging material 1 and packed into a carton made of cardboard with an upper lid 2 and a lower lid 3. The cheese filling method is as shown in Figure 2.
Approximately 75~ in cheese packaging material 1 folded into
After a certain amount of melted cheese heated to 85° C. is filled, the opening of the packaging material 1 is folded in so as to tightly contact the melted cheese, and the lower lid 3 is inserted. The filled carton is then sealed using the packaging material used to package the cheese by applying pressure from the top, bottom, left and right sides.
Packaging of processed cheese is completed. On the other hand, there is also a method shown in FIG. 3 for folding the cheese packaging material 1 into the carton top lid 2. In other words, both sides of the cheese packaging material 1 are sealed with a pressure sealer shown in FIG. 4, and then the cheese packaging material 1 is inserted into the carton top cover. Since cheese uses the above-mentioned filling method, the inner sealing layer of the cheese packaging material must be sealed only by the heat of the filled cheese, or must be sufficiently sealed by only crimping. . Furthermore, the sealing layer of the cheese packaging material has excellent adhesion to melted cheese.
The melted cheese must flow into every corner of the container formed by the packaging material without leaving any spaces. This is because if air remains during packaging, mold will grow in that area. Furthermore, when cheese is eaten, it is cut with a kitchen knife, knife, etc. while still being wrapped in the packaging material, so it has been desired that the packaging material for cheese be one that can be easily cut with a kitchen knife, knife, etc. As shown in Japanese Patent Publication No. 32-5447, this packaging material for cheese is made by heating and melting coating of a mixture of polyisobutylene, low molecular weight polyethylene, paraffin wax, Microcrys, Talin wax, etc. on cellophane or moisture-proof cellophane. was common. When the sealing layer used in the cheese packaging material disclosed in this publication is filled with molten cheese, the surface of the sealing layer melts and adheres to the surface of the cheese, and can also be heat-sealed and crimped only by the heat of the molten cheese. It was possible to seal it. However, the sealing layer is made of polyisobutylene, low molecular weight polyethylene, paraffin wax, microcrystalline wax, etc., and it is necessary to mix materials with different softening points and melt viscosities, which requires a special blender. Moreover, since this mixed resin has a high melt viscosity, a dedicated special coating device was required. The coated seal layer may block if pressure is applied or the temperature rises when it is stored before use, and temperature control of the processing atmosphere and handling operations for winding are complicated. It was hot.
Furthermore, in order to obtain sufficient sealing performance with the packaging material using this mixed resin as a sealing layer as shown in the above publication, the coating amount of the mixed resin was required to be 60 to 80 g/m ² . When filling and packaging processed cheese using a packaging material as explained above, there is a drawback that if too much pressure is applied, the mixed resin will protrude from the sealing part and fuse to the bottom lid. Since the cohesive force is small, a part of the sealing layer adheres to the cheese when the packaging material is peeled off from the cheese. Next, the typical packaging material used for heat-melting filling of yokan is paper/aluminum foil/polyethylene, and as shown in Figure 5, it has a cylindrical shape with a spine sealed and is heat-sealed to the bottom. It is something. It was common practice to fill the container with yokan melted at 80 to 95°C and heat-seal the top and bottom. Since this packaging material contains aluminum foil, it has excellent barrier properties and can extend the shelf life to about one year. However, if the above-mentioned packaging material is used to fill the yokan, air bubbles in the molten yokan will accumulate at the top, and since the sealing method uses hot rolls, the shape of the bottom and top of the yokan will be distorted, reducing the commercial value of both sides. In addition, since it contains aluminum foil, it is opaque, making it impossible to see the yokan, making it difficult to express the characteristics of chestnut yokan, Ogura yokan, etc. The object of the present invention is to enable sealing of heat-melted foods such as cheese, yokan, etc. by only heat or pressure bonding of the foods to be filled, without using heat rolls, etc., with good adhesion, and to allow cooling and solidification of the foods. rear,
An object of the present invention is to obtain a packaging material having a resin layer that does not adhere to foods and can be easily peeled off. Another object is to obtain a packaging material having a resin layer that requires less coating than before and can be easily formed by extrusion coating. The present invention will be explained below. In the present invention, a vinyl acetate content of 5 to 40 wt% is formed on a transparent substrate made of cellophane or plastic film or a composite material thereof.
Ethylene vinyl acetate copolymer (A) with a molecular weight of 6000
A copolymer (B) of ~20,000 ethylene or α-olefin and unsaturated carboxylic acid with a weight ratio of A:B of 99
~60: 20 to 45 resin (C) mixed in the range of 1 to 40
This is a packaging material suitable for filling and packaging heat-melted foods, with a resin layer formed by extrusion coating to a thickness of g/m ² . Further, the resin layer may include a tackifier added to the resin (C) in an amount of 3 to 30 wt%, making the packaging material suitable for filling and packaging heat-melted foods. Here, if the vinyl acetate content of the ethylene-vinyl acetate copolymer (A) is 5 wt% or less, heat sealing of the hot-melt filling only by heat becomes incomplete, and ethylene or α-olefin and unsaturated carboxylic acid or its The compatibility with the anhydride copolymer (B) is poor, resulting in poor extrusion coating processability. Furthermore, if the vinyl acetate content is 40 wt% or more, the suitability for extrusion coating is poor, the yield is reduced, and the applied resin film becomes sticky, resulting in poor filling workability with the hot-melt filling. Next, the copolymer (B) of ethylene or α-olefin and unsaturated carboxylic acid or its anhydride will be explained. Ethylene or α-olefin is a polymer of ethylene represented by the general formula CnH ₂ n and having a carbon double bond at the end, and those with n=2 to 100 showed good results. Among these, especially n = 20~
A range of 40 showed good results. As unsaturated carboxylic acids, acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid were particularly effective in the present invention. The molecular weight of the copolymer (B) used in the resin layer of the present invention is determined based on the compatibility with the ethylene-vinyl acetate copolymer, the flow of the hot melt to be filled, and the adhesion with the cooled and solidified filling. The effect was large and the best results were obtained in the range of 6000 to 20000. Addition of a tackifier not only further improves the heat sealability but also enables sealing using only pressure at room temperature. Table 1 shows a comparison of laminated materials provided with a resin layer made of a tackifier-free composition and a tackifier-added composition. The composition of the packaging material used here is as follows.

【table】

[Table] As shown in Table 1, by adding a tackifier, the resin layers can be crimped and sealed with a pressure sealer at room temperature, making it easy to seal them. The tackifier is made of any one of aliphatic hydrocarbon resins, aromatic hydrocarbon resins, copolymerized hydrocarbon resins, or a mixture thereof. The tackifier consists of the above-mentioned resin with either a rosin derivative or a modified rosin derivative attached thereto. Since the resin layer of the present invention uses a resin with good compatibility, the resin phase can be formed by extrusion coating using a general extruder for extrusion coating by turning the mixed resin into pellets. The resin layer of the present invention has 20 to 45
Sufficient sealing and sealing performance can be obtained with a coating amount of g/m ² , and the resin seals completely due to the heat of the filling material and the pressure applied, but there is a risk that the resin may protrude from the sealed area due to these. There is no. Furthermore, the problem of the resin layer adhering to the filling when the package is opened, which is caused by the resin layer's weak cohesive force, has also been resolved. Next, examples of the present invention will be described. Example 1 Polyvinylidene chloride coated cellophane (25μ)
A mixed resin having the following composition was extrusion coated on top at about 150°C to form a resin layer and obtain a packaging material. Ethylene-vinyl acetate copolymer 90 parts (vinyl acetate content 33wt% melt index 30g/10 min) C ₃₀ H ₆₀ - C ₄₀ H ₈₀ α-olefin and maleic anhydride copolymer 10 parts The obtained packaging material was filled and packaged with processed cheese having a heating melting temperature of 85° C. in the manner described above, and after pressurized from above and below and from both sides for about 1 hour, it was left in a refrigerator for 2 hours. As a result, a processed cheese package with excellent adhesion between the packaging material and the cheese and with much better transparency than before was obtained. Further, cutting with a knife was easy, no elongation of the resin layer was observed, and when slicing into thin slices, there was no shift of the packaging material, causing no problems. In addition, in order to examine the sealability, the processed cheese package was immersed in a 0.3% methylene blue water-methanol (water/methanol = 1/1) solution for 5 hours, and then opened and the coloring of the cheese was observed. could not be seen at all. Furthermore, after being stored in a constant temperature and humidity room at 20° C. and 50% RH for two months, the condition of the processed cheese was examined and found to be in a sufficiently satisfactory condition with no mold growth or loss of moisture. Example 2 A resin layer having the following composition was extrusion coated on a polyvinylidene chloride-coated polyethylene terephthalate film (12μ) at about 150°C to form a resin layer to obtain a packaging material. Ethylene-vinyl acetate copolymer 70 parts (vinyl acetate content 19% wt melt index 15 g/10 min) C ₂₀ H ₄₀ - C ₃₀ H ₆₀ copolymer of α-olefin and fumaric acid 15 parts Copolymer carbonization Hydrogen resin (softening point: 80°C, molecular weight: 750) 9 parts Hydrogenated rosin glycerin ester (softening point: 78°C) 6 parts To the packaging material obtained in this way, kneaded yokan with a heating melting temperature of 105°C was added using the method described above. It was filled and packaged, and after pressurizing from the top and bottom and left and right sides for about 1 hour, it was left in the refrigerator for 2 hours. As a result, a Yokan package was obtained which had no leakage or oozing of Yokan, had good transparency, and was very effective as a product. It was also easy to cut with a knife. Further 25℃−
There was no change in the color or taste of the yokan even after 6 months of storage in a 60% RH constant temperature and humidity room, and of course there was no decrease in moisture content. Since the packaging material of the present invention has the above-mentioned structure, it is possible to ensure sufficient sealing performance with approximately 1/2 the amount of resin layer applied in similar conventional packaging materials. There is no risk of the resin extruding from the sealed part due to pressure, and since it has excellent adhesion to food, it can be packaged without leaving any air during filling, so there is no risk of mold forming during storage. On the other hand, after the food has cooled and solidified, the resin layer can be easily peeled off without adhering to the food.
Moreover, the food can be easily cut with a knife or the like while still being packaged. In addition, since the resin layer can be formed on the base material by extrusion coating, it can be easily formed not only on cellophane but also on plastic films and composite materials thereof, and has a resin layer with excellent moisture and gas barrier properties. Transparent packaging materials can be obtained, and packaging with high product effectiveness that allows the contents to be seen through has become possible.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a processed cheese package, Figs. 2 and 3 are explanatory diagrams showing the manufacturing process of processed cheese, Fig. 4 is an explanatory diagram of the pressure sealing method, and Fig. 5 is an explanatory diagram of the process cheese manufacturing process.
The figure is an explanatory diagram of the current packaging form of Yokan. 1...Packaging material, 2...Top lid, 3...Bottom lid, 4
...Foldable type.

Claims (1)

[Claims] 1. On a transparent substrate made of cellophane, plastic film, or a composite material thereof, an ethylene-vinyl acetate copolymer (A) having a vinyl acetate content of 5 to 40 wt% and a molecular weight of A copolymer (B) of 6,000 to 20,000 ethylene or α-olefin and unsaturated carboxylic acid in a weight ratio of A:B of 99 to 60:1 to
A packaging material suitable for filling and packaging heat-melted foods, which has a resin layer formed by extrusion coating a resin (C) mixed in a range of 40 to 45 g/m ² to a thickness of 20 to 45 g/m 2 . 2. On a transparent substrate made of cellophane, plastic film, or a composite material thereof, an ethylene-vinyl acetate copolymer (A) having a vinyl acetate content of 5 to 40 wt% and ethylene or The copolymer (B) of α-olefin and unsaturated carboxylic acid has a weight ratio of A:B of 99 to 60:1.
Add tackifier (D) to resin (C) mixed in the range of 40 to 3
A packaging material suitable for filling and packaging heat-melted foods, which has a resin layer formed by extrusion coating a resin mixed in a range of 30 wt% to a thickness of 20 to 45 g/ ^m2 .