JP4200153B2 - Resin composition for molding bag with chuck - Google Patents

Description

  The present invention relates to a bag with a fitting (hereinafter referred to as a chuck) mainly composed of aliphatic polyamide. More specifically, the present invention relates to a bag with a chuck made of a resin composition of ethylene / acrylic acid or methacrylic acid or a derivative copolymer thereof mainly composed of an aliphatic polyamide having a crystal melting point of 190 ° C. to 270 ° C. This bag can be thawed or cooked by microwave heating in a microwave oven in a state of being filled with frozen food or refrigerated food.

Synthetic resin bags whose openings can be easily resealed are used for food packaging, pharmaceutical packaging, and the like because they are easy to handle and are convenient for storing and storing small portions. Among these, as storage bags for food packaging for freezing and refrigeration at home, synthetic resin bags with a chuck that can dispense food, and freezing bags with heat resistance that can be reheated by a microwave oven are commercially available. Yes. As a bag with a chuck using polyamide as a film base material, polyolefin such as polyethylene and polypropylene is laminated as a heat-sealable layer (hereinafter referred to as a sealant layer or sealant) on a polycapramide (hereinafter referred to as nylon 6). Multi-layer bags are commercially available. Further, in the following patent document, an easily tearable laminate film containing 40 to 85 parts by weight of nylon 6 and 15 to 60 parts by weight of metaxylylene adipamide was formed as a single layer. A bag body made of an easily tearable laminate film and an easily tearable bag with an occlusion device having an occlusion device at an opening portion of the bag body are disclosed. These bag films require a material other than polyamide as a sealant. This is because, with the exception of some polyamides such as polylaurolactam (hereinafter referred to as nylon 12) and copolymers thereof, it is difficult to obtain the sealing strength required for a package with a single polyamide. Therefore, it is necessary to form a laminate of a polyamide layer and a sealant layer, which requires steps such as a lamination method and a coextrusion method.
JP 7-125756 A

  Nylon 6 itself does not have a function as a sealant. Therefore, in order to manufacture a conventional bag with a chuck made of nylon 6, it has a laminated structure in which a sealant layer is further arranged, or a chuck member is formed separately. Manufacturing equipment was complicated, such as welding to the bag body. The object of the present invention is a single-layer film consisting of a resin composition mainly composed of a polyamide resin and also having a function as a sealant, and sufficient sealing strength and cold resistance without using another resin layer as a sealant layer. Another object of the present invention is to provide a resin composition for forming a bag with a zipper having heat resistance and transparency.

  As a result of researches on aliphatic polyamides to solve the above-mentioned problems, the inventors have found that aliphatic polyamides having a crystalline melting point of 190 ° C. to 270 ° C. are 60% by mass to 90% by mass, and specific compatibility with this. In order to complete the present invention, it is found that a film composed of 40% by mass to 10% by mass of a resin can provide a bag body with a chuck that itself has a function as a sealant and satisfies the other properties described above. It came.

  That is, the present invention includes 60% by mass to 90% by mass, preferably 70% by mass to 85% by mass of an aliphatic polyamide having a crystal melting point of 190 ° C. to 270 ° C. as the first component, and ethylene / acrylic acid as the second component. 40% by mass to 10% by mass of a resin selected from the group consisting of a polymer, an ethylene / methacrylic acid copolymer, an ethylene / alkyl acrylate copolymer and an ethylene / alkyl methacrylate copolymer, preferably 30% by mass. A resin composition for forming a bag with a zipper comprising a mixed resin of 15 to 15% by mass.

  The bag with a chuck made of the resin composition of the present invention has only a single layer film as shown in the examples, and has a lower seal than the single layer film of aliphatic polyamide and the two layer film of aliphatic polyamide / vinyl acetate. It exhibits a predetermined sealing strength at a temperature, does not substantially impair transparency, and has heat resistance and cold resistance. Further, since the chuck can be integrally formed, there is an advantage that the production equipment and the process are not complicated.

  The amount of the first component resin used is required to be 60% by mass or more from the viewpoint of imparting heat resistance, and 90% by mass or less is necessary to ensure the sealing strength. Further, the resin of the second component needs to be 10% by mass or more in order to impart sealability, and should not exceed 40% by mass in order to maintain the transparency and heat resistance of the film. The bag of the present invention must withstand reheating by a microwave oven, and in order to ensure a heat resistant temperature of 180 ° C. or higher according to a test method described later, the resin of the first component is a resin having a crystal melting point of 190 ° C. or higher. Use. However, a resin having a crystal melting point exceeding 270 ° C. is not preferable because it becomes difficult to form a film. The preferred melting point of the first component resin is 195 ° C. to 265 ° C. Nylon 6 and caprolactam / hexamethylene diammonium adipate copolymer (hereinafter referred to as nylon 6,66) are preferably used. When an ethylene / methacrylic acid copolymer is used as the second component resin, nylon 6 is particularly preferable as the first component resin.

The second component resin preferably has compatibility with the first component resin, has rubber elasticity and behaves like an elastomer, and has a lower melting point than the first component resin. When a resin having a low melting point is used as the second component resin, the low temperature impact strength based on ASTM D3763 can be improved, but the heat resistance is lowered. Therefore, the selection of the second component resin may be performed in consideration of these balances. In addition, adding the second component leads to a loss of transparency of the film, but by selecting appropriately, as shown in the examples, to produce a bag body that does not impair the transparency in practical evaluation. Can do. Considering these factors and maintaining the sealing strength, the preferred second component resin is ethylene (content 70 mass to 95 mass%) / methacrylic acid copolymer, ethylene / methacrylic acid methyl ester copolymer. An ethylene / methacrylic acid ethyl ester copolymer can be preferably mentioned . In terms of low temperature impact strength of al, terpolymer of ethylene-methacrylic acid-acrylic acid alkyl ester is preferable as the resin of the second component, in particular, the terpolymer of nylon 6, 66 (first A mixed resin with component) is most preferred.

  As a sealing method for manufacturing a bag body with a chuck, a face seal is adopted in a known method using an olefin resin as a sealant. In the present invention, both surface sealing and wire sealing are possible, but in the examples, wire sealing at the time of fusing sealing is exemplified. In this method, the films are melt-sealed with a heated blade and cut at the same time, and the seal portion becomes a line seal.

In the present invention, the seal strength means the seal strength (wire seal strength) at the time of fusing sealing. Further, the expression of sealing properties in the present invention means that the following conditions are satisfied at a sealing temperature of 280 ° C. or lower.
(1) The seal strength should be greater than 1.5 kgf / 15 mm width (test sealer conditions: pressure 1 kgf / cm ² , pressure bonding time 1 second).
(2) The elongation of the film in a sealed state is greater than 50%.
Specifically, it is preferable that the seal strength exceeds the yield strength of the material film, and the material film breaks before the seal portion breaks. If the film of the material is not stretched even though the sealing strength is high, there is a concern that the food contents may leak due to impact under high temperature during re-cooking. The film employed in the present invention needs to satisfy the above requirements at a sealing temperature of 280 ° C. or lower, but the sealing operation itself is preferably performed at a higher temperature in order to obtain sufficient sealing strength.

Manufacturing of a bag body with a chuck includes a method in which a chuck portion and a bag body are formed separately, and a method in which the chuck portion and the bag body are welded and a method in which a chuck is integrally formed in a die at the same time when the bag body is formed. However, in the case of using the monolayer film of the present invention, it can be produced by either method. The method for producing the film of the present invention is not particularly limited. The film may be stretched or an unstretched film. The thickness of the film is 30 μm to 150 μm, preferably 40 μm to 100 μm. Manufacture of the bag body with a chuck | zipper can be performed as follows, for example. First, an aliphatic polyamide having a melting point of 190 ° C. to 270 ° C. serving as a first component and a second component resin selected from the resins having compatibility therewith are mixed at a predetermined ratio. This mixing method is not particularly limited, and may be blended by equipment or mixed pellets by a melt kneader. The predetermined resin mixture is supplied to an extruder, and a chuck is integrally formed inside a tube film serving as a bag body and extruded in a cylindrical die provided with male and female notches for forming a chuck portion on the die. The melt with a chuck coming out of the die is water-cooled and widened by an inflation method to obtain an unstretched tube film. By sealing and fusing the tube film with a chuck with a bag making machine having a fusing seal function under the conditions of a bag making speed of 1 shot (bag) / sec, a seal temperature of 300 ° C., and a seal pressure of 1 kgf / cm ² , A bag with a chuck can be obtained. The desirable thickness of the bag body with a chuck thus obtained is 30 μm to 150 μm, and more desirably 40 μm to 100 μm. In addition, it is preferable that the single layer film which comprises a bag body with a chuck | zipper is an unstretched film. Moreover, there is no restriction | limiting in particular about the shape of a chuck | zipper.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The measurement methods used in the examples are as follows.
Seal strength: The seal strength was measured by a Tensilon universal testing machine (TMIRTM 100 type, manufactured by Orientec Co., Ltd.) by a 180 degree peel test method. Both ends of the test piece including the seal portion (width 15 mm, length 50 mm) via the seal portion were sandwiched between holders, and the strength when the tensile seal portion was cut at a chuck speed of 200 mm / min was measured. At the same time, the elongation of the test piece was measured.
Haze (haze): measured in accordance with JIS K-7105. The measurement was performed using a Nippon Denshoku Industries Co., Ltd. haze meter (Z-Σ80 type).
Heat resistance: A sample having a length of 14 cm and a width of 3 cm on both sides of a test piece of 2.5 cm overlapped with a piece of paper having the same width (3 cm) as the test piece and fixed with an adhesive tape was used as a sample. The upper part of each 2.5 cm edge of the board that overlaps the test piece is fixed to a jig, a load of 10 gf is applied to the lower end, it is quickly put in a gear oven adjusted to a constant temperature and heated for 1 hour. Then, the sample is examined for the presence of cutting after heating. The test temperature is set in increments of 5 ° C. If the sample does not cut after 1 hour, the temperature is increased by 5 ° C and the above operation is repeated. The indicated heat-resistant temperature is the maximum temperature at which the sample is not cut.
Cold shock resistance resistance: measured in accordance with ASTM D-3763. The measurement device was a drop weight tester (Model RDT-5000) manufactured by REOMETRICS, and the sample temperature was set to −10 ° C. for measurement.

80% by mass of nylon 6 (product name: Amilan CM1021 crystal melting point 225 ° C.) and ethylene / methacrylic acid copolymer (EMAA) resin (trade name: Nuclel 0903HC, crystal melting point 98 ° C., methacrylic acid, manufactured by Toray Industries, Inc. 20% by mass) is mixed with a tumbler, extruded downward with a cylindrical die provided with male and female cuts in a 40 mm diameter extruder, water-cooled, and formed into a film by an inflation method. An unstretched tubular film having a film thickness of 50 μm and a diameter of 100 mm was obtained by integrally forming a chuck inside. This tube film with a chuck is sealed and cut by a bag making machine with a fusing seal function at a bag making speed of 1 bag / second, a seal temperature of 300 ° C., and a seal pressure of 1 kgf / cm ² , with a chuck of 200 mm in width and 150 mm in length. A bag was obtained.

In addition, the tube-shaped film with the chuck before being applied to the bag making machine obtained as described above was fixed with a heat tester (manufactured by Tester Sangyo Co., Ltd.) at a pressure bonding time of 1 second and a pressure of 1 kgf / cm ² . Fusing heat sealing was performed at different temperatures. Table 1 shows the results of measuring the 180 ° peel strength (seal strength), elongation, haze, heat resistance and cold impact strength at −10 ° C. of this film. Moreover, the following practical evaluation was performed about the bag body with a chuck | zipper obtained by the above. Each of the five bags with chucks was filled with 600 g of curry, stored frozen in a refrigerator for one day, and thawed with a microwave oven. Although the degree of biting of the chuck portion was observed, no curry exudation from this portion was observed in all five bags. Also, no oozing from the film portion was observed in all 5 bags. Furthermore, although it heated for 30 minutes with "strong" with the microwave oven (MR-M220 type | mold made by Toshiba Corporation), the leak of the seal part, the pinhole on the film surface, etc. were not recognized. The contents in the bag were sufficiently visible from the outside, and the transparency was not impaired.

  In place of EMAA in Example 1, ethylene / methacrylic acid / isobutyl acrylate copolymer (EMAAI) resin (manufactured by Mitsui DuPont Polychemical Co., Ltd .: trade name Nucleel AN-42171C, crystal melting point 89 ° C., methacrylic acid content 10% by mass) A bag with a chuck was produced in the same manner as in Example 1 except that was used, and practical evaluation was performed. As a result, the same results as in Example 1 were obtained. Further, Table 1 shows the result of the same test as in Example 1 for this film.

  A bag with a chuck was manufactured and practically evaluated in the same manner as in Example 1 except that nylon 6 of Example 2 was replaced with nylon 6,66 (manufactured by Toray Industries, Inc .: trade name Amilan CM6041, crystal melting point 195 ° C.). As a result, the same results as in Example 1 were obtained. Further, Table 1 shows the result of the same test as in Example 1 for this film.

  A bag with a chuck as in Example 2 except that nylon 6 of Example 2 is replaced with polyhexamethylene sebacamide (nylon 6, 10) (trade name: Amilan CM2001, crystal melting point 222 ° C., manufactured by Toray Industries, Inc.) When practical evaluation was carried out, the same results as in Example 1 were obtained.

  A bag with a chuck is manufactured in the same manner as in Example 2 except that nylon 6 of Example 2 is replaced with polyhexamethylene adipamide (nylon 66) (trade name: Amilan CM3001, crystal melting point 265 ° C., manufactured by Toray Industries, Inc.) When practical evaluation was performed, the same results as in Example 1 were obtained.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that only nylon 6 alone was used without using EMAA. Table 1 shows the results of the same test as in Example 1 for this film. Further, practical evaluation similar to that in Example 1 was performed. When stuffed curry and frozen for one day in a refrigerator were thawed with a microwave oven, curry ooze out from the biting part of the chuck part in all five bags. Furthermore, when heated for 30 minutes with a microwave oven (MR-M220, manufactured by Toshiba Corp.) for 30 minutes, leakage of the seal portion was observed in 2 of 5 bags.

[Comparative Example 2]
Except for using EMAA in Example 1 and using ethylene / vinyl acetate copolymer (manufactured by Sumitomo Chemical Co., Ltd .: trade name Evaate D2011, crystal melting point 103 ° C., vinyl acetate content 5 mass%), the same as in Example 1. went. The test results of this film are shown in Table 1. In the practical evaluation similar to Example 1, the curry stuffed and stored in the refrigerator for one day was thawed in the microwave oven, and exudation of curry from the biting part of the chuck part was observed in all five bags. However, when heated for 30 minutes with a microwave oven (MR-M220, manufactured by Toshiba Corp.) for 30 minutes, leakage at the seal portion was observed in 4 of 5 bags.

[Comparative Example 3]
Implementation was carried out except that a partially neutralized product (made by Mitsui DuPont Polychemical Co., Ltd .: trade name Himiran 1601, crystal melting point 96 ° C.) using zinc ions of an ethylene / methacrylic acid copolymer was used instead of EMAA in Example 1. A film was produced as in Example 1. In the practical evaluation similar to Example 1, the curry stuffed and stored in the refrigerator for one day was thawed in the microwave oven, and exudation of curry from the biting part of the chuck part was observed in all five bags. However, when heated for 30 minutes with a microwave oven (MR-M220, manufactured by Toshiba Corp.) for 30 minutes, leakage at the seal portion was observed in 4 of 5 bags.

Claims (3)

  60% to 90% by weight of aliphatic polyamide having a crystalline melting point of 190 ° C. to 270 ° C. as the first component, and ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / alkyl acrylate ester as the second component A mixed resin of 40% by mass to 10% by mass of one or more resins selected from the group consisting of a copolymer, an ethylene / methacrylic acid alkyl ester copolymer and an ethylene / methacrylic acid / acrylic acid alkyl terpolymer A resin composition for forming a bag with a chuck comprising:   The resin composition for forming a bag with a chuck according to claim 1, wherein the first component is a caprolactam / hexamethylene diammonium adipate copolymer, and the second component is an ethylene / methacrylic acid copolymer. The resin composition for forming a bag with a chuck according to claim 1 or 2, wherein the second component is a terpolymer of ethylene, methacrylic acid, and alkyl acrylate.