JP2007290740A - Laminated film for packaging iodine and packing bag using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film, etc. for packaging iodine which is superior in resistance and barrier functionalities relative to iodine, facilitates packaging work to match with automation, and prevents a heat seal part from being broken during its packaging and distribution processes or when the same is formed in a packaging bag. <P>SOLUTION: This relates to a laminated film comprising at least a base material layer and a heat seal layer for packaging iodine. The heat seal layer is provided with a stretched film layer formed of a polyvinylidene chloride and a polyvinylidene chloride latex coated film layer overlying the opposite side of the base material layer of the stretched film layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated film used for a bag for packaging iodine and a packaging bag using the same.

  Iodine is used in intermediates for organic synthesis, pharmaceuticals, and the like, and is distributed in the form of flakes, crushed materials, and granular materials. Iodine has a high sublimation property and has a property of being slightly vaporized even at room temperature. Further, since iodine gas is highly permeable, it is reduced in the storage and distribution process of a polyolefin film alone. In addition, when using a laminated film with polyolefin as a heat seal layer, weight loss from the heat seal portion cannot be prevented, and further, the adhesive layer and the like are damaged by iodine, resulting in film peeling and film strength reduction. Arise. Therefore, in the circulation of iodine, a packaging bag made of polyvinylidene chloride (hereinafter referred to as PVDC) film having excellent resistance to iodine and barrier properties is used.

  However, since the PVDC film alone has insufficient film strength, the strength as a packaging bag is also insufficient. Therefore, the PVDC packaging bag is used as an inner bag of double bag packaging with another resin bag as an outer bag on the outside. However, in such a packaging form, since the operation | work which accommodates this in an outer bag after throwing an iodine in the inner bag made from a PVDC film, there existed a fault that the packaging workability | operativity of iodine was very bad. . In addition, since it cannot respond to the automation of packaging work, it has become an obstacle to rationalization and labor saving.

  Therefore, an intermediate layer provided between the inner layer, the outer layer, and the inner layer and the outer layer for the purpose of providing a packaging bag for iodine that can sufficiently withstand storage of iodine for a long period of time and has good handleability. In an iodine packaging bag composed of a laminate including a layer, the inner layer is composed of polyvinylidene chloride, the outer layer is composed of a reinforcing material for reinforcing the inner layer and the intermediate layer, and the intermediate layer is composed of a polyolefin. A packaging bag is disclosed (for example, see Patent Document 1). The laminated film used in this packaging bag is a single film, and has an excellent performance against iodine and barrier properties due to the inner PVDC film, and a sufficient film strength due to, for example, a nylon resin film in the outer layer. Have.

However, in the packaging bag formed by heat-sealing, the heat-seal strength of the inner layer PVDC film is weak, so that the heat-sealing part of the bag is broken in the process of charging, packaging and distributing iodine. And could not be used practically.
JP 2005-8253 A

  For iodine packaging that has excellent resistance to iodine and barrier properties, is easy to wrap and can be automated, and does not break in the packaging process or distribution process and does not break the heat seal part when used as a packaging bag It is an object to provide a film or the like.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have reached the present invention. That is, the present invention is as follows.
(1) A laminated film for iodine packaging comprising at least a base material layer and a heat seal layer, wherein the heat seal layer comprises the stretched film layer made of polyvinylidene chloride and the stretched film layer made of polyvinylidene chloride. A laminated film for iodine packaging, comprising a coating layer of polyvinylidene chloride latex laminated on the opposite side of the layer.
(2) The film for iodine packaging according to (1) above, wherein the coating layer has a thickness of 3 to 20 μm.
(3) The laminated film for iodine packaging as described in (1) or (2) above, wherein the stretched film made of polyvinylidene chloride has a thickness of 10 to 50 μm.
(4) The iodine packaging multilayer film according to any one of (1) to (3) above, wherein an intermediate layer made of a polyolefin resin is provided between the base material layer and the heat seal layer.
(5) A packaging bag for iodine formed by heat-sealing the laminated film according to any one of (1) to (4) above.

  Although it is for iodine packaging, the heat seal strength of the laminated film is large, and the packaging bag is not destroyed. Moreover, since it is composed of a single film, the packaging operation is easy and can be automated. In addition, it has excellent resistance to iodine and barrier properties, and is free from iodine loss, alteration, or bag breakage in the distribution process, and excellent in content protection.

  Embodiments of the present invention will be specifically described with reference to the drawings. The laminated film of the present invention comprises at least a base material layer and a heat seal layer, and the heat seal layer is a layer using a stretched film made of polyvinylidene chloride and the side opposite to the base material layer of the stretched film layer made of polyvinylidene chloride. And a coating layer of polyvinylidene chloride latex provided on the surface. FIG. 1 is a schematic view showing a cross-sectional configuration of an example 10 of the laminated film of the present invention.

  In the laminated film 10, a base material layer 11 and a heat seal layer 12 are bonded together via an adhesive layer 13. The heat seal layer 12 includes a PVDC film layer 14 and a coating layer 15 provided by coating a PVDC latex on the surface opposite to the base material layer 11 of the PVDC film layer 14 and drying it.

  The PVDC latex is obtained by dispersing and emulsifying PVDC in water by a known method. The PVDC latex can be formed into a coating layer by coating on the film surface and drying. The PVDC used here may be a polymer of vinylidene chloride alone or may be a copolymer with another monomer, but is preferably a copolymer in order to improve the low temperature heat sealability. Specific examples of the copolymerizable monomer include vinyl chloride, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic esters such as 2-hydroxyethyl acrylate, methyl methacrylate, and methacrylic acid. Examples include methacrylic acid esters such as glycidyl, acrylonitrile, methacrylonitrile, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc. Can be used.

  The content of vinylidene chloride in PVDC needs to be 50% by weight or more for iodine barrier properties, and preferably 80 to 92% by weight. You may add emulsifiers, such as surfactant, pH adjusters, such as ammonia, etc. to PVDC latex as needed. Moreover, since the latex coating layer serves as a heat seal surface of the laminated film, a slipping agent can be added to improve the slipping property of the laminated film, or an antiblocking agent can be added to prevent blocking.

  Next, the PVDC film is obtained by melt-extrusion of a monomer mixture that becomes PVDC to form a film. Stretching to give orientation makes it difficult for the film to crack even if the film is bent or deformed. The stretching may be uniaxial stretching, but biaxial stretching is preferred because cracks are less likely to occur.

  The PVDC used for the PVDC film may be a polymer of vinylidene chloride alone or may be a copolymer with another monomer, but is preferably a copolymer in order to improve the extrusion processability. Specific examples of monomers copolymerizable with vinylidene chloride include acrylic acid esters such as vinyl chloride, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, Examples include methacrylic acid esters such as glycidyl methacrylate, acrylonitrile, methacrylonitrile, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and the like. It can be selected and used.

  The vinylidene chloride content of PVDC is required to be 50% by weight or more for iodine barrier properties, and preferably 80 to 97% by weight. A heat stabilizer, a plasticizer, a slip agent, etc. can be added to PVDC as needed. The production method of the film may be in accordance with a known method. For example, a tubular stretching method in which a film is extruded from a circular die into a tube shape, and air is pressed in and biaxially stretched can be used.

  The PVDC latex coating layer is provided on the surface of the PVDC film opposite to the side laminated with the base material layer. In order to provide the coating layer, PVDC latex may be applied, coated, transferred, sprayed, etc. to form a thin layer on the surface and then dried. Alternatively, the PVDC latex may be formed into a thin film by a casting method or the like, and may be laminated with the PCDC stretched film without being stretched. The outer surface of the coating layer thus formed becomes a heat seal surface.

  Here, the role of the PVDC film layer and the PVDC latex coating layer constituting the heat seal layer will be described. The PVDC film layer is responsible for barrier properties and resistance to iodine. PVDC has high crystallinity and is brittle as it is and easily cracks due to bending or deformation caused by heat sealing pressure. However, when stretched and oriented, it does not crack even when bent or deformed. However, since it has high crystallinity, it is crystallized into a layer shape when stretched, and therefore, it tends to be coherently broken so that it peels off in a mica-like manner against the stress that is pulled in the thickness direction of the film. For this reason, if only the PVDC film is used as the heat seal layer, the heat seal strength is weak, and the packaging bag formed from the heat seal layer is destroyed from the heat seal portion during filling or transportation.

  However, when a PVDC latex coating layer is provided on the surface of the PVDC film layer opposite to the base material layer, such cohesive failure is less likely to occur. The reason why cohesive failure is less likely to occur is unknown, but by providing a coating layer, the tensile stress is once applied to the coating layer, causing a shift in the direction of the stress, and this shift relaxes the stress applied to the PVDC film. As a result, it is speculated that cohesive failure is less likely to occur, and the heat seal strength is drastically improved.

  If only the PVDC latex coating layer is used without using the PVDC film, the PVDC crystals are not oriented and are brittle, and cracks are caused by bending, deformation due to heat sealing pressure, or the like. Therefore, the iodine vaporized from here penetrates, causing a decrease or alteration of iodine, peeling of the laminated film, and a decrease in strength.

  The thickness of the PVDC latex layer is preferably 3 μm or more in order to sufficiently relax the stress applied to the PVDC film and further increase the heat seal strength of the laminated film. The thickness of the PVDC latex layer is preferably 20 μm or less. Further, the thickness of the PVDC film layer is preferably 10 μm or more in order to prevent the reduction or alteration of iodine in the package and the peeling or strength reduction of the laminated film as much as possible, and the laminated film becomes hard and has a handleability as a packaging bag. In order to prevent the decrease as much as possible, 50 μm or less is preferable.

  The base material layer is a layer that bears the mechanical strength of the laminated film, particularly the tensile strength. In addition, when used as a package, it also has a role of preventing a laminated film from being rubbed with an exterior such as a fiber drum. Further, when the laminated film is heat sealed to form a packaging bag, it also serves as a heat-resistant layer that prevents the laminated film from being deformed by heat. As the base material layer, a biaxially stretched film generally used for a laminated film for soft packaging can be used. Specifically, a nylon-6 film, a nylon-66 film, a metaxylene azimuth film, and the like. Polyamide film such as Pamide nylon film, nylon film such as nylon-6 co-extruded metaxylene adipamide nylon, polyethylene terephthalate film, polybutylene terephthalate film, polyethylene naphthalate film, polypropylene A film or the like can be used. If necessary, the same film or two or more kinds of films may be laminated and used.

  The thickness of the base material layer is preferably 10 μm or more for giving a high tensile strength to the laminated film, and preferably 60 μm or less for preventing the laminated film from becoming hard and reducing the handleability as a packaging bag as much as possible.

  The base material layer and the heat seal layer are preferably laminated via an adhesive layer. As the adhesive, those generally used for laminated films for soft packaging can be used, and specific examples include two-component curable urethane adhesives and ethylene-acrylic acid copolymer resins. .

  In the laminated film, an intermediate layer of polyolefin resin can be provided between the base material layer and the heat seal layer. By providing the intermediate layer of the polyolefin resin, the mechanical strength can be further improved without making the laminated film hard, and the performance of preventing perforations due to rubbing with the exterior can be further enhanced. FIG. 2 is a schematic view showing a cross-sectional configuration of an example in which an intermediate layer is further provided on the laminated film of FIG. In the laminated film 20, it can be seen that the intermediate layer 24 is bonded between the base film 21 and the heat seal layer 22 via two adhesive layers 23. The layer 22 further comprises a PVDC film layer 25 and a coating layer 26 coated with PVDC latex and dried.

  As the polyolefin resin used here, known resins can be used. Specifically, polyethylene such as high-pressure method low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc., and polypropylene homopolymer. Examples thereof include polypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-acrylic acid copolymer, ionomer, and the like such as polymers, block copolymers, and random copolymers.

  The thickness of the intermediate layer is preferably 10 μm or more in order to sufficiently improve the film strength, and 100 μm or less in order to maintain a good handling property as a packaging bag because the laminated film is soft. Is preferred.

  The intermediate layer may be formed by laminating a polyolefin resin film with the base material layer and the heat seal layer by a dry laminating method, or by laminating the base material layer and the heat seal layer by an extrusion sand laminating method. Alternatively, a polyolefin resin film may be extruded and bonded to the base material layer and the heat seal layer by a sand lamination method, or the above methods may be combined. The dry laminating method is a method in which an adhesive is applied to the surface of the film and dried, and then bonded to another film by pressure bonding. A two-component curable urethane adhesive is suitably used for the adhesive layer. . The extrusion sand laminating method is an excellent method because the resin is melted, extruded from a T-die in a thin film shape, and sandwiched between two films and bonded together, so that adhesion and formation of an intermediate layer can be performed simultaneously. In this case as well, an adhesive layer is necessary, but since the adhesive layer can be made very thin as compared with the dry lamination method, the laminated film can be formed softly. As an adhesive layer of the extrusion sand laminating method, a polyethyleneimine adhesive may be used in addition to the two-component curable urethane adhesive.

  A method for making a packaging bag for iodine using a laminated film may follow a known bag-making method generally used for laminated films for soft packaging. For example, there is a method in which the heat seal layer surfaces of the laminated film are opposed to each other, the heat seal layer is heated and melted, pressed and heat sealed, cooled and solidified, and stabilized. Examples of the heat sealing heating and pressure bonding methods include, but are not limited to, a bar sealing method, a heat roller method, a belt sealing method, an impulse sealing method, and a high frequency sealing method. Moreover, about the form of a packaging bag, a general well-known form can be taken for soft packaging. Specific examples of the form include a three-sided seal bag, a pillow bag, a pillow gazette bag, and a four-corner seal gadget bag, but are not limited thereto.

  As a method of using the packaging bag, for example, there is a method in which iodine is introduced from the opening of the packaging bag and then the opening is heat-sealed to form a sealed package. However, the method is not limited thereto. Further, if necessary, an exterior such as a fiber drum, a cardboard box, a plastic or metal return box can be used.

  As described above, the laminated film described above has a sufficient heat-sealing strength, a high sublimation property such as iodine, high vapor permeability, high permeability, and a material that easily alters various materials. Can be transported and stored. Therefore, this laminated film can also be used as a packaging material for other alcohols, organic solvents, and chemicals.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to the specific aspect of the following Example. In addition, the measuring method and evaluation method of various physical properties in the examples are as follows.
(A) Tensile strength

According to the direction of measuring the film, 5 pieces were cut out to a width of 15 mm to obtain test pieces. In accordance with JIS-K7127, the tensile strength was determined by the test speed E method (50 mm / min).
(B) Heat seal strength

Two sheets of 100 mm width were cut out according to the direction of measuring the film, the heat seal surfaces were made to face each other, and heat sealing was performed with a hot plate having a width of 10 mm and a temperature of 180 ° C. under conditions of a sealing pressure of 98 kPa and a sealing time of 1 second. . Five test pieces having a width of 15 mm were cut out from this sample, and the heat seal strength was determined according to JIS-Z0238. The above measurement operation was repeated 5 times, and a total of 25 test pieces were measured, and a maximum value, a minimum value, and an average value were obtained.
(C) Resistance to iodine

Using a film, create a bag with an outer dimension of 120 mm wide and 180 mm long, heat sealed on three sides to a seal width of 10 mm, put 200 g of iodine into this, heat sealed the opening and sealed The body. This was stored under two types of storage conditions. The first was a condition of storing for 60 days under conditions of 23 ° C. and a relative humidity of 50%, and the second was a condition of storing for 10 days under conditions of 40 ° C. and a relative humidity of 90%. In either case, it was visually observed whether or not peeling occurred on the film of the package after storage.
(D) Transport durability

  Using a film, a bag having an outer dimension of a rectangle having a width of 500 mm and a length of 850 mm and heat-sealed on three sides with a seal width of 10 mm was prepared. This bag was put in a fiber drum having an inner diameter of 300 mm and an inner height of 400 mm, 50 kg of iodine was put in the bag, and the opening was heat sealed and sealed. The lid of the fiber drum was closed to make a package for evaluation. In accordance with JIS-Z0200, the vibration duration was 40 minutes in the vertical direction, the horizontal direction was changed to a right angle for 20 minutes, the vibration test was performed under the conditions of the frequency of 5 to 50 Hz and the peak acceleration of ± 0.75 G. . After completion of the test, the lid of the fiber drum was opened, and the state of the packaging bag inside was visually observed.

  A biaxially stretched nylon film “Harden film N1100 (trade name)” (thickness 15 μm) manufactured by Toyobo Co., Ltd. is used as the base layer, and “Saran UB film (trade name)” (thickness) manufactured by Asahi Kasei Life and Living Corp. is used as the PVDC film. 15 μm), and a two-component curable urethane adhesive LX-901 manufactured by Dainippon Ink & Chemicals, Inc. and KW40 mixed at a specified blending ratio on each bonded surface side, and a dry thickness of 0.7 μm The high pressure method low density polyethylene “Novatech LD (trade name), LC600A” manufactured by Nippon Polyethylene Co., Ltd. was laminated between the two films by extrusion sand lamination so as to have a thickness of 30 μm. .

  Next, PSA latex “L502” manufactured by Asahi Kasei Chemicals Co., Ltd. was applied to the Saran UB film surface side while applying corona treatment, and dried to a dry thickness of 6 μm to obtain a laminated film for iodine packaging.

  Next, the tensile strength of the laminated film was measured according to the method (a). The results are shown in Table 1. As for the tensile strength, the film flow direction (hereinafter referred to as MD direction) was 69 N / 15 mm width, and the width direction (hereinafter referred to as TD direction) was 71 N / 15 mm width, showing sufficient strength.

  Next, the heat seal strength of the laminated film was measured according to the method (b). The results are shown in Table 1. Heat seal strength in MD direction is maximum value 40N / 15mm width, minimum value 35N / 15mm width, average value 38N / 15mm width, TD direction is maximum value 38N / 15mm width, minimum value 34N / 15mm width, average value 36N / 15mm The width was small, the variation in strength was small, and sufficient strength was shown.

  Next, according to the method (c), the resistance to iodine when the laminated film was used as a packaging bag for iodine was evaluated. The results are shown in Table 1. Under any of the conditions, the laminated film did not swell or peel off, and was sufficiently resistant to iodine.

  Next, the durability against transportation was evaluated according to the method of (d) above. The results are shown in Table 1. The packaging bag after the vibration test did not tear the film, did not break the heat seal portion, and had sufficient durability for transportation.

Comparative Example 1

  A biaxially stretched nylon film “Harden film N1100 (trade name)” (thickness 15 μm) manufactured by Toyobo Co., Ltd. is used as the base layer, and “Saran UB film (trade name)” (thickness) manufactured by Asahi Kasei Life and Living Corp. is used as the PVDC film. 15 μm), and a two-component curable urethane adhesive LX-901 manufactured by Dainippon Ink & Chemicals, Inc. and KW40 mixed at a specified blending ratio on each bonded surface side, and a dry thickness of 0.7 μm After being coated, the high pressure method low density polyethylene “Novatech LD (trade name), LC600A” manufactured by Nippon Polyethylene Co., Ltd. is laminated between the two films by an extrusion sand laminating method to a thickness of 30 μm. A test film was obtained.

  Next, the tensile strength of the laminated film was measured according to the method (a). The results are shown in Table 1. The tensile strength was 66 N / 15 mm width in the film flow direction (hereinafter referred to as MD direction) and 66 N / 15 mm width in the width direction (hereinafter referred to as TD direction), indicating sufficient strength.

  Next, the heat seal strength of the laminated film was measured according to the method (b). The results are shown in Table 1. Heat seal strength in MD direction is maximum value 33N / 15mm width, minimum value 13N / 15mm width, average value 22N / 15mm width, TD direction is maximum value 28N / 15mm width, minimum value 11N / 15mm width, average value 18N / 15mm The width is not only low in strength as a whole, but also has a very small strength due to large variations in strength.

  Next, according to the method (c), the resistance to iodine when the laminated film was used as a packaging bag for iodine was evaluated. The results are shown in Table 1. Under any of the conditions, the laminated film did not swell or peel off, and was sufficiently resistant to iodine.

  Next, the durability against transportation was evaluated according to the method of (d) above. The results are shown in Table 1. The packaging bag after the vibration test did not tear the film, but there was a portion where the heat seal portion was broken, and the durability against transportation was insufficient.

It is the schematic diagram which showed the cross-sectional structure about an example of the laminated | multilayer film. It is the schematic diagram which showed the cross-sectional structure about another example of a laminated | multilayer film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated film 11 Base material layer 12 Heat seal layer 13 Adhesive layer 14 PVDC film layer 15 PVDC latex coating layer 20 Laminated film 21 Base material layer 22 Heat seal layer 23 Adhesive layer 24 Intermediate layer 25 PVDC film layer 26 PVDC latex film layer

Claims (5)

  A laminated film for iodine packaging comprising at least a base material layer and a heat seal layer, wherein the heat seal layer is opposite to the base film layer of the polyvinylidene chloride stretched film layer and the polyvinylidene chloride stretched film layer. A laminated film for iodine packaging, comprising: a polyvinylidene chloride latex film laminated on the side.   The thickness of the said coating layer is 3-20 micrometers, The laminated | multilayer film for iodine packaging of Claim 1 characterized by the above-mentioned.   The laminated film for iodine packaging according to claim 1 or 2, wherein the stretched film made of polyvinylidene chloride has a thickness of 10 to 50 µm.   The laminated film for iodine packaging according to any one of claims 1 to 3, further comprising an intermediate layer made of a polyolefin resin between the base material layer and the heat seal layer. The packaging bag for iodine formed by heat-sealing the laminated | multilayer film of any one of Claims 1-4.

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