JP2008284700A - Heat-sealable laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sealable laminated film which is excellent in heat sealability, mechanical properties, especially, rigidity and slipperiness, suitable for bag packaging of food articles such as vegetables and fish foods, and performing overlap packaging of sweet treats, drug medicines, cassette tapes, is excellent in protection of content and sealability, and also has beauty of packaging appearance. <P>SOLUTION: The heat-sealable laminated film where the difference of the rising temperature of the heat seal between the heat seal layers (B) and (C) is 10°C or more, and the melting point of the heat seal layer (B) is higher than the melting point of the heat seal layer (C) in a laminated body having the heat seal layers (B) and (C) made of a polyolefin-based resin is constituted on both surfaces of the substrate layer (A) made of polypropylene-based resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat-sealable laminated film, more specifically, heat sealability and mechanical properties, in particular, excellent rigidity and slipperiness, and packaging of foodstuffs such as vegetables and fish meat, confectionery, pharmaceuticals, and cassette tapes. The present invention relates to a heat-sealable laminated film that is suitable for overlapping packaging, etc., has excellent content protection and sealing properties, and has a beautiful packaging appearance.

  Conventionally, polypropylene resin films have been widely used in fields such as food packaging and fiber packaging because they have excellent optical properties, mechanical properties, packaging suitability, and the like. Among these, heat-sealable films with a polypropylene resin film as a base resin film and a low melting point polyolefin-based resin laminated on the surface are often used for bag packaging of food products such as vegetables and fish meat, and especially fin seal packaging. It is suitably used as an overlapping packaging material for confectionery, pharmaceuticals, cassette tapes and the like used.

However, in recent years, the packaging form has become more sophisticated, especially pharmaceuticals and highly hygroscopic confectionery, insect contamination due to leakage of scents, and prevention of tampering with products, and the outer and inner surfaces of the film are heat-sealed and then folded. After wrapping the film wrapping material with the opening tape around the article from the so-called overlap wrapping, the film wrapping material is formed into a cylindrical shape by heat-sealing with the back surfaces of both ends overlapped with each other Close and form a fin seal band, and with the fin seal band folded into the article side, heat seal both ends of the tubular film wrapping material together with both ends of the fin seal band in the form of the same fin seal. The so-called fin-seal packaging that is obtained in this way has come to be used (for example, Patent Documents 1, 2, etc.) Ether.).
JP-A-8-91430 JP 2002-284109 A

  However, when a heat-sealable laminated film (for example, see Patent Document 2) conventionally used for overlap packaging is used for fin-seal packaging, the inner surfaces of the films are heat-sealed and then matched to the shape of the contents. When folding and heat-sealing the outer surfaces, heat seal heat causes poor appearance such as wrinkles, and folding causes multiple films to overlap, causing the folded part to be flipped with a high waist feeling, resulting in poor heat sealing May occur.

  The present invention solves these problems and is excellent in mechanical properties, in particular, rigidity and slipperiness as well as heat sealability, such as bag packaging of foodstuffs such as vegetables and fish meat, confectionery, pharmaceuticals, cassette tapes, etc. An object of the present invention is to provide a heat-sealable laminated film that is suitable for overlapping packaging, has excellent contents protection and sealing properties, and has a beautiful packaging appearance.

As a result of intensive studies to achieve the above object, the present invention has been completed.
That is, the present invention provides a heat seal layer (B), (C) in a laminate having heat seal layers (B), (C) made of polyolefin resin on both sides of a base material layer (A) made of polypropylene resin. A heat-sealable laminated film characterized in that the difference in heat-sealing rise temperature is 10 ° C. or more and the melting point of the heat-seal layer (B) is higher than that of the heat-seal layer (C).

  In this case, it is preferable that the heat-sealable laminated film is a biaxially stretched heat-sealable laminated film stretched 3 to 8 times in the longitudinal direction and 4 to 10 times in the transverse direction.

  The heat-sealable laminated film of the present invention is excellent in mechanical properties, in particular, rigidity and slipperiness as well as heat-sealability, and is often used for bag packaging of foodstuffs such as vegetables and fish meat, and in particular, fin-seal packaging. It has the advantages of protecting the contents of medicines, cassette tapes, etc., having excellent sealing properties, and having a beautiful package appearance.

Hereinafter, embodiments of the heat-sealable laminated film of the present invention will be described.
The heat-sealable laminated film of the present invention is a laminate having heat seal layers (B) and (C) made of a polyolefin resin on both surfaces of a base material layer (A) made of a polypropylene resin.
It is necessary that the difference between the heat seal rising temperatures of the heat seal layers (B) and (C) is 10 ° C. or more. When the difference in these heat seal rise temperatures is less than 10 ° C., when forming a fin seal band, the heat seal heat causes poor appearance such as wrinkles, or folding causes multiple films to overlap, resulting in a high waist feeling. The folded portion is bounced and a heat seal defect occurs, resulting in a problem of heat seal defect. This is because the heat seal rising temperature difference is small, so that the heat seal temperature when forming the fin seal band needs to be higher than necessary.

  The heat seal rising temperature means a temperature at which heat seal strength = 1 [N / 15 mm]. Specifically, a film sample is cut into a width of 50 mm × 500 mm, heat sealed using a thermal inclination tester (HG-100, manufactured by Toyo Seiki Co., Ltd.) at a pressure of 98 kPa and a pressure bonding time of 1 second, and the heat seal portion is 15 mm wide. The maximum load when the heat seal part peeled off was read with a tensile tester (manufactured by Shimadzu Corporation, Autograph AGS-1) at a pulling speed of 200 mm / min, and the heat seal strength was read. The temperature was changed from 80 ° C. by 10 ° C. and plotted on the coordinates of temperature-heat seal strength to determine the heat seal rising temperature.

  The heat seal layer (B) needs to be higher than the melting point of the heat seal layer (C). When the heat seal layer (B) is not higher than the melting point of the heat seal layer (C), the intended package, packaging suitability and beautiful appearance cannot be obtained. This is because when the fin seal band is formed, the fin seal portion is wrinkled, peeled off or repelled, resulting in a heat seal failure. The heat seal layer (B) is a surface on the package contents side, and is also a layer to be heat sealed first.

  The polypropylene resin forming the base material layer (A) in the present invention is crystalline polypropylene, which is a homopolypropylene, or a copolymer or terpolymer obtained by copolymerizing ethylene, butene, pentene, hexene or the like. It does not matter, but homopolypropylene is preferred because the film tension of the package becomes good.

  Here, the polyolefin resin forming the heat seal layers (B) and (C) is a polyolefin resin having a lower melting point than the polypropylene resin forming the base layer (A).・ Butene-1 copolymer, ethylene / propylene / butene-1 copolymer, ethylene / acrylic acid copolymer, ionomer obtained by crosslinking ethylene / acrylic acid copolymer with metal ion, polybutene-1, butene / ethylene copolymer One kind or two or more kinds of polymers, propylene / ethylene copolymers, propylene / butene-1 copolymers, propylene / pentene copolymers, etc. may be used, or polypropylene and a mixture thereof may be used. There is no limitation as long as heat sealability according to the purpose and application can be obtained.

  Next, although the manufacturing method of the heat-sealable laminated film of this invention is demonstrated, it is not limited to the method as described in this specification.

  The blending method of the raw materials of the base material layer (A) and the heat seal layer (B) (C) of the heat sealable film in the present invention is not particularly limited, but is a V-type blender, a screw-type blender, a drive renderer. In general, the mixture is uniformly mixed using a mixer such as a ribbon blender or a Henschel mixer, and then kneaded and pelletized.

A film can be manufactured by the method illustrated below using the obtained pellet.
(1) Using three extruders, a resin composition for forming a base material layer from one extruder is melt-extruded, and a resin composition for forming a heat seal layer from each of the remaining two extruders A method in which a product is melt-extruded, laminated in and out of a die, laminated, and then stretched.
(2) The laminate obtained by extruding the base material layer (A) and the heat seal layer (B) or (C) in advance into a sheet is stretched as it is or uniaxially stretched, and the heat seal layer (B) is formed on the other surface. Or the method of melt-extrusion laminating | stacking (C) and then extending | stretching. At this time, the heat seal layer should not be the same resin layer.

  The production conditions of the film of the present invention can be appropriately set for the purpose of obtaining general physical properties such as desired heat sealability, slipperiness, and appearance, and are not different from, for example, general polyolefin film formation conditions. It can be obtained by stretching a sheet obtained by solidifying a resin composition melt-extruded at an extrusion temperature of 150 to 300 ° C. with a cooling roll of 10 to 100 ° C.

  In addition, it is recommended that the heat-sealable laminated film of the present invention is produced by a biaxial stretching method, and can be carried out by a simultaneous biaxial stretching method, a sequential biaxial stretching method, an inflation method, etc. Is common. In the said extending process, it can be extended | stretched by about 8-50 times by the area magnification, Preferably it is about 10-40 times.

  In the above biaxial stretching, the conditions for performing sequential biaxial stretching are as follows: First, the roll is heated to 100 to 150 ° C. in the longitudinal direction and stretched about 3 to 8 times between rolls having a peripheral speed difference, and then the width direction. The film is stretched about 4 to 10 times at a temperature of about 140 to 170 ° C. using a tenter. Thereafter, after heat-setting at a temperature of 150 to 170 ° C., a heat-sealable laminated film can be obtained by winding.

  In addition, the heat-sealable laminated film of the present invention is subjected to corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, flame treatment, etc. to improve the wettability of the film surface. It is a preferred embodiment for various packaging films. However, since it has a great influence on heat sealability and slipperiness, it is necessary to give a surface treatment in consideration of these characteristics. The surface treatment may be performed by a so-called in-line process performed in the film manufacturing process, or may be performed by a so-called off-line process in which the manufactured film is processed as a subsequent process.

  Moreover, it is also possible to mix | blend various additives in the said base material layer (A), a heat seal layer (B), and (C) in the range which does not deviate from the main point of this invention, Specifically, , Antistatic agents, slip agents, antifogging agents, antioxidants, ultraviolet absorbers, adsorbents, antibacterial agents, flame retardants, concealing agents and the like.

  The heat-sealable laminated film of the present invention is suitably used as a bag packaging for foodstuffs such as vegetables and fish meat, and particularly as an overlap packaging material for confectionery, pharmaceuticals, cassette tapes, etc., in which fin seal packaging is often used. The

  Hereinafter, specific examples of the present invention will be further described by way of examples. However, the present invention is not limited to the following examples without departing from the gist thereof. In addition, the measuring method of the characteristic value in this specification is as follows.

(Melting point)
About 5 mg of polyolefin resin was weighed and heated to 200 ° C. at a temperature rising rate of 10 ° C./min using a differential scanning calorimeter (DSC-60) manufactured by Shimadzu Corporation and held at 200 ° C. for 5 minutes. Then, after cooling to 0 ° C. at a temperature lowering rate of 10 ° C./min, the melting point (melting peak temperature) when the temperature is raised again to 200 ° C. at 10 ° C./min is obtained.

(Heat seal rise temperature)
As an evaluation of heat sealability, a heat seal rising temperature (temperature at which heat seal strength = 1 [N / 15 mm]) was obtained. A film sample is cut into a width of 50 mm × 500 mm, heat sealed using a thermal inclination tester (HG-100, manufactured by Toyo Seiki Co., Ltd.) with a pressure of 98 kPa and a pressure bonding time of 1 second, and a heat seal portion is cut out to a width of 15 mm and subjected to a tensile test. The maximum load when the heat seal part peels off was read with a machine (manufactured by Shimadzu Corporation, Autograph AGS-1) at a pulling speed of 200 mm / min. The temperature was changed from 80 ° C. by 10 ° C. and plotted on the coordinates of temperature-heat seal strength to determine the heat seal rising temperature.

(Fin seal packaging suitability)
The heat-sealing laminated film was back-sealed seal part 150 ° C., bottom seal part 155 ° C., folding seal part 135 ° C., speed 100 m / min using a fin seal type overlap wrapping machine FN4 manufactured by Tokyo Automatic Machinery Co., Ltd. It carried out in.
The appearance of the folding seal part as well as the back sticking / bottom seal part was observed. Further, a leak value, which is an index of air leak, was measured with a leak tester. The leak tester is a measurement method in which air is injected into the package with an injection needle and air is leaked from the seal portion, and the amount of injected air is regarded as the amount of leak. When the injection amount is 0 ml, the leak value is 0 ml.

Example 1
In the sequential biaxial stretching method, the base material layer was 45% by weight of polypropylene resin FS7053G3 manufactured by Sumitomo Chemical Co., Ltd., 55% by weight of WF836DG3, and 50 FSX66E8 manufactured by Sumitomo Chemical Co., Ltd. was used as the heat seal layer (B). 1% by weight, 50% by weight of FSX66J6, 35% by weight of XM7070 manufactured by Mitsui Chemicals, Inc., and 65% by weight of FSX66J6 manufactured by Sumitomo Chemical Co., Ltd. as the other heat seal layer (C) Lamination was performed to obtain the desired heat-sealable laminated film. The total thickness at this time was 25 μm, the heat seal layer (B) was 1.0 μm, and the heat seal layer (C) was 2.0 μm.
The suitability was good, and a beautiful appearance was obtained not only on the back-sealed / bottom-sealed part but also on the folded seal part. The leak value, which is an index of air leak, was also 0 ml, which was good.

(Example 2)
A heat-sealable laminated film obtained by subjecting the heat seal layer (B) of Example 1 to corona treatment with a treatment power of 1.45 kW using a corona treatment machine manufactured by Kasuga Electric Co., Ltd.
The packaging suitability was good, and a beautiful appearance was obtained in the folding seal part. Further, the leak value was 0 ml, which was good.

(Example 3)
The heat seal layer (B) of Example 1 was 100% by weight of FSX66M4 manufactured by Sumitomo Chemical Co., Ltd., the heat seal layer (C) was 100% by weight of SPX78P9 manufactured by Sumitomo Chemical Co., Ltd., and the heat seal layer (B ) Is a heat-sealable laminated film that has been subjected to corona treatment with a treatment power of 1.45 kW using a corona treatment machine manufactured by Kasuga Electric Co., Ltd.
The packaging suitability was good, and a beautiful appearance was obtained in the folding seal part. Further, the leak value was 0 ml, which was good.

(Comparative Example 1)
A heat-sealable laminated film in which the heat seal layer (B) of Example 1 is 35% by weight of XM7070 manufactured by Mitsui Chemicals, Inc. and 65% by weight of FSX66J6 manufactured by Sumitomo Chemical Co., Ltd.
As for packaging suitability, the back-sealed / bottom-sealed portion and the folding seal portion were fused to the heat-seal bar by heat of the heat seal, resulting in poor appearance. The leak value was 100 ml, which was poor.

(Comparative Example 2)
A heat-sealable laminated film in which the heat seal layer (C) of Example 1 is 50% by weight of FSX66E8 manufactured by Sumitomo Chemical Co., Ltd. and 50% by weight of FSX66J6.
As for packaging suitability, the back sticking / bottom seal part was able to be sealed well, but the folding seal part was repelled and the appearance was poor. The leak value was 150 ml, which was poor.

(Comparative Example 3)
A heat-sealable laminated film obtained by subjecting the heat seal layer (B) of Comparative Example 2 to corona treatment at a treatment power of 1.45 kW using a corona treatment machine manufactured by Kasuga Electric Co., Ltd.
As for packaging suitability, the back-sealed / bottom-sealed part was able to seal well, but the folding seal part bounced off the seal part, resulting in poor appearance. The leak value was 120 ml, which was poor.

  The results are shown in Table 1.

  The heat-sealable laminated film of the present invention is excellent in mechanical properties, in particular, rigidity and slipperiness as well as heat-sealability, content protection, sealing properties, and beauty of packaging appearance. It is suitable for overlapping packaging such as sachets, confectionery, medicines, cassette tapes, etc., and contributes to the industry.

Claims (2)

  Heat seal rising temperature of heat seal layers (B) and (C) in a laminate having heat seal layers (B) and (C) made of polyolefin resin on both sides of a base material layer (A) made of polypropylene resin The heat-sealable laminated film is characterized in that the difference is 10 ° C. or more and the melting point of the heat seal layer (B) is higher than the melting point of the heat seal layer (C).   A biaxially stretched heat-sealable laminate film obtained by stretching the laminate of claim 1 3 to 8 times in the longitudinal direction and 4 to 10 times in the transverse direction.