JP7386488B2 - Packaging material, its manufacturing method, and a bag for housing a heat-generating composition and a heating element using the same - Google Patents

Description

The present invention relates to a packaging material for a bag for accommodating a heat-generating composition that generates heat by reacting with air (oxygen), a method for manufacturing this packaging material, and a bag body for accommodating a heat-generating composition and a heating element using this packaging material.

2. Description of the Related Art A heating body that includes a breathable bag containing a heat generating composition that generates heat upon contact with air is generally widely used as a medical tool for alleviating pain through heat, a body warmer for protecting against the cold, and the like. Such heating elements can be roughly divided into those that are attached to clothing or the body, and those that are not attached. Heating elements that are not attached to clothing or the body (hereinafter sometimes referred to as "hand warmer types") are basically intended to be used by being held in the hand or stored in the pocket of clothing or a supporter. It is designed. The hand warmer type also includes a heating body that has a member for being attached to the hand or other body parts.

The packaging material forming the bag for containing the heat-generating composition prevents the heat-generating composition, which is black or nearly black in color and contains a large amount of black substances such as iron powder and activated carbon, from being seen through from the outside. Therefore, it is required to have concealment properties. In addition, in order to prevent the packaging material from deforming or deteriorating due to heat generation, or from leaking the exothermic composition due to tearing or breaking of the seal during use, the strength of the packaging material itself and the seal strength of the joints are also required. Desired.

To meet these demands, packaging materials generally consist of a nonwoven fabric layer used to provide heat resistance and strength, and a film layer used to provide heat sealability and strength. It is formed of.

As a manufacturing method for this packaging material, a tandem lamination method is often used in which two film layers are extruded and laminated on a nonwoven fabric in one step. In this case, the first layer is usually a transparent low-density polyethylene (LDPE) for adhesion to the nonwoven fabric, and the second layer is a transparent metallocene-catalyzed linear low-density polyethylene (mLLDPE) for heat sealing. processed to do so. The whiteness and degree of concealment necessary for packaging materials are adjusted by nonwoven fabrics.

Furthermore, instead of the tandem lamination method, a method is also used in which a single layer of transparent LDPE for adhesion is extruded and laminated as an intermediate layer between a pre-formed cast film and a nonwoven fabric. In this case, the whiteness and degree of concealment of the packaging material are adjusted using nonwoven fabric or cast film.

Generally, the tandem lamination method allows the resin to be oxidized and activated, resulting in a packaging material with a more flexible finish. However, with the tandem lamination method, it is difficult to obtain sufficient lamination strength with the nonwoven fabric, and more energy is consumed to increase the resin temperature during processing of transparent LDPE for bonding to improve flow adhesion. etc. is necessary.

Japanese Patent Application Publication No. 11-56894 Japanese Patent Application Publication No. 2002-209926 Japanese Patent Application Publication No. 2007-83552 Japanese Patent Application Publication No. 2011-104993

Since hand warmer-type heating elements are used while being touched by the hands or by changing the position of application to the body, a highly flexible packaging material is particularly desired. The present invention provides a packaging material suitable for use as a packaging material for a bag containing a heat-generating composition, which is highly flexible and has high lamination strength, and can be used for a hand warmer type heating element. The present invention aims to provide a packaging material that is well-balanced in terms of flexibility, manufacturing economy, etc., and a method for manufacturing such a packaging material. A further object of the present invention is to provide a heat-generating composition storage bag and a heating element that are excellent in terms of strength, flexibility, manufacturing economy, etc., using such a packaging material.

The present inventors have conducted extensive studies to achieve the above-mentioned problems and have arrived at the present invention. That is, according to the present invention,
[1] A packaging material for configuring a bag containing a heat-generating composition that generates heat in the presence of air, which comprises a nonwoven fabric layer, a first resin film layer containing a pigment, and a heat-sealable resin layer. a second resin film layer having, in this order;
[2] The packaging material according to [1] above, wherein the heat-sealable resin layer is located on the surface of the second resin film layer so as to be heat-sealable with a mating film or sheet;
[3] The packaging material according to [1] or [2] above, wherein the pigment contains titanium oxide or calcium carbonate;
[4] The packaging material according to any one of [1] to [3] above, wherein the first resin film layer is made of low-density polyethylene;
[5] The packaging material according to any one of [1] to [4] above, wherein the heat-sealable resin layer is made of metallocene catalyst-based linear low-density polyethylene;
[6] A method for producing the packaging material according to any one of [1] to [5] above, which comprises: laminating the first resin film layer containing a pigment on the nonwoven fabric layer; A method comprising the step of laminating a second resin film layer having a heat-sealable resin layer on the resin film layer;
[7] The method described in [6] above, wherein the lamination is performed by a tandem lamination method;
[8] A bag for housing a heat-generating composition, at least one side of which is formed of the packaging material according to any one of [1] to [5] above;
[9] A heating body comprising the bag according to [8] above and a heat generating composition that generates heat in the presence of air contained in the bag;
[10] The heating body according to [9] is provided, which is housed in an airtight outer bag.

According to the present invention, there is provided a packaging material that can be easily manufactured by a tandem lamination method and is not only highly flexible but also has sufficient strength to be suitable for a hand warmer type heating element. According to the present invention, both the lamination strength of the nonwoven fabric and the resin film and the heat seal strength with the mating packaging material during bag formation can be improved. Furthermore, the whiteness and hiding degree of the packaging material can be easily increased by using only the resin film layer for adhesion.

The packaging material of the present invention is a laminated sheet, and basically consists of a nonwoven fabric layer, a first resin film layer that has an adhesive function between the nonwoven fabric layer and a second resin film layer, and a mating packaging material during bag making. and a second resin film layer that performs a heat sealing function.

Non-woven fabric Non-woven fabric is generally used in a bag for containing a heat-generating composition or a packaging material for a heating element from the viewpoint of absorbing sweat when the heating element is used, reinforcing the strength of the packaging material, and improving mechanical suitability. The nonwoven fabric used in the packaging material of the present invention is not particularly limited, and any nonwoven fabric may be used. For example, those conventionally used in technical fields such as heating bodies and medical heating tools can be suitably used. Specifically, the material includes olefin resins, particularly polyethylene or polypropylene resins, such as nylon, vinylon, polyester, rayon, acetate, acrylic, polyethylene (PE), polypropylene (PP), polyvinyl chloride, It can be a nonwoven fabric containing artificial fibers such as polyethylene terephthalate (PET) and/or natural fibers such as cotton, linen, silk, etc. Generally, nonwoven fabrics such as nylon, polyester, and rayon are preferably used.

The fibers constituting the nonwoven fabric may be composite fibers containing a plurality of resins, mixed yarns, etc., and the lower limit of the melting point of the fibers constituting the nonwoven fabric may be about 120°C, preferably 130°C or higher. The melting point is more preferably 150°C or higher, most preferably 180°C or higher. The upper limit of the melting point is generally about 300°C, although there is no particular restriction. In addition, in the case of a composite fiber such as a core-sheath structure, it is preferable that the melting point of the fiber constituting the surface (sheath) is within the above range. Examples of such composite fibers include composite fibers in which the core is made of polypropylene and the sheath is made of polyester.

Examples of methods for producing nonwoven fabrics include spunbond, thermal bond, and spunlace.

The basis weight of the nonwoven fabric varies depending on the specific gravity of the nonwoven fabric material and the bulk due to the difference in the interlacing method, but in general, about 10 g/m ² to about 200 g/m ² is suitable, especially about 10 g/m ² to about 200 g/m 2 About 100 g/m ² is preferred, and about 10 g/m ² to about 50 g/m ² is most preferred. In the production of a heating element, when the packaging material is heat-sealed at high speed during bag making, the thinner the packaging material, the better the heat conduction, and the heating element can be manufactured economically. Therefore, in order to particularly improve heat conduction when the packaging material of the present invention is used for bag making using high-speed heat rolls, a nonwoven fabric having a basis weight of about 15 to about 40 g/m ² is most preferable.

First Resin Film Layer The first resin film layer is located between the nonwoven fabric layer and the second resin film layer, and serves to bond them together. As the resin forming the first resin film layer, an olefin resin can be used, and examples thereof include polyethylene resin, polypropylene resin, ethylene vinyl acetate copolymer (EVA), and the like. Examples of the polyethylene resin include high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. Examples of the polypropylene resin include homopolypropylene, random polypropylene, and the like. Low density polyethylene is preferred.

The melting point of the resin of the first resin film layer is preferably 90°C or higher, more preferably 100°C or higher. The upper limit of the melting point is preferably 130°C or lower, more preferably 120°C or lower. The thickness of the first resin film layer is generally about 5 μm to 100 μm, most preferably about 10 μm to 50 μm. When high-speed heat sealing is applied, in the packaging material of the present invention, the first resin film layer most preferably has a thickness of 15 to 40 μm.

In the present invention, this first resin film layer is characterized in that it contains a pigment. It is thought that this improves the thermal conductivity of the resin film, improves the fluid adhesiveness of the resin, improves the lamination strength, and improves the heat sealing strength.

The pigment is not particularly limited as long as it has the effect of enhancing the hiding power of the film. Examples include inorganic pigments, organic pigments, or so-called opalescent ceramics, such as silica, titanium oxide, calcium carbonate, magnesium oxide, sodium oxide, alumina, iron oxide, and calcium oxide. Particularly preferred are titanium oxide or calcium carbonate. One type of pigment may be used, or two or more types may be used.

The amount of pigment added can be in the range of 2 to 30% by weight net of the pigment, based on the weight of the first resin as 100%. A range of 3 to 20% by weight is particularly preferred.

Second Resin Film Layer The second resin film layer is not particularly limited as long as it contains a resin with heat sealability, and may be a single layer film or a multilayer film. The heat-sealable resin layer is located on the surface of the second resin film layer so that it can be heat-sealed with the other film or sheet to be heat-sealed, that is, on the nonwoven fabric side (first resin film layer side). Place it so that it is exposed to the outside. The mating film or sheet is not particularly limited as long as it can be heat-sealed. As the heat-sealable resin layer, olefin resins are particularly preferable, and polyethylene is particularly preferable, particularly low-density polyethylene, linear low-density polyethylene (LLDPE), metallocene catalyst-based linear low-density polyethylene, or those containing the same. Most preferred.

The second resin film layer may consist only of a heat-sealable resin layer, but other layers may also be present. As the resin of the additional layer which may be present, thermoplastic synthetic resins and the like are generally used. Specifically, polyethylene, polypropylene, polyester, polyamide, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyurethane, polystyrene, ethylene-vinyl acetate copolymer, polycarbonate, etc. are preferably used alone or in combination.

The thickness of the second resin film layer is generally about 3 μm to 100 μm, most preferably about 5 μm to 50 μm. When heat sealing is applied at high speed, the thickness of the second resin film layer in the packaging material of the present invention is most preferably 10 to 30 μm.

Method for manufacturing packaging material The packaging material of the present invention can be manufactured by any conventionally known method. For example, it can be manufactured by forming each film layer in advance by a known method and then laminating it with a nonwoven fabric by a known method such as dry lamination or hot melt lamination. Each layer may be laminated by thermal bonding, hot melt adhesive, acrylic adhesive, urethane adhesive, or other adhesive, or may be entirely bonded, or may be partially bonded to maintain flexibility. good. A lamination method is preferred, and an extrusion lamination method is most preferred.

The tandem lamination method is particularly advantageous because it allows two layers of films to be successively laminated in one step, resulting in a laminated sheet with excellent flexibility. Specifically, the resin of the first resin film layer is laminated to the nonwoven fabric layer by a first tandem extrusion lamination method, and then the resin of the second resin film layer is laminated to the first resin film layer. Lamination can be performed using a second tandem extrusion lamination method.

The thus obtained laminated sheet packaging material can be substantially non-breathable. In the context of the present invention, "substantially" non-breathable means, in addition to completely non-breathable, something with some breathability due to pinholes generated during manufacturing, and non-breathable packaging in a heating element. The purpose is to include materials that have sufficient breathability to be used as materials. In other words, if the product has not been intentionally processed to make it porous or perforated during the manufacturing process, and its breathability is sufficient to allow it to be used as a non-breathable packaging material for a heating element, ( (substantially) non-breathable.

The substantially non-breathable packaging material produced as described above can also be made into a breathable packaging material by perforating it with a known method such as a needle or laser.

Thermal element The heating element of the present invention basically comprises a bag for containing a heat-generating composition and a heat-generating composition contained therein, and the bag for containing a heat-generating composition is provided with the packaging material of the present invention on at least one surface thereof. There is. The heating body of the present invention may include any additional elements in addition to the above configuration.

At least one surface (ventilation surface) of the heat-generating composition storage bag is composed of a breathable film (or sheet). As the breathable film, a single-layer or multilayer porous film (particularly a stretched porous film) is generally used, and a laminate film of a porous film and a nonwoven fabric is preferably used. Examples of the resin constituting the porous film include polyethylene, polypropylene, polyfluoroethylene, and the like. Among these, polyethylene is preferred, and linear low-density polyethylene (LLDPE) is particularly preferred from the viewpoint of processability and the like. These can be used alone or in combination. The packaging material constituting the ventilation surface may be the packaging material of the present invention that is perforated with a needle or laser and has air permeability.

The heat-generating composition in the heating element of the present invention is not limited in type, and any conventionally known composition that generates heat in the presence of air can be used, and among them, a heat-generating composition using metal powder is preferably used. The exothermic composition used in the present invention usually contains at least metal powder, salts, water, and a water retention agent (activated carbon).

Iron powder is generally used as the metal powder, but other metal powders may be used as long as they generate heat of oxidation. As salts, inorganic salts such as sodium chloride, potassium chloride, and magnesium chloride are generally used. Activated carbon is generally used as the water-retaining agent, but water-retaining agents other than activated carbon (for example, water-absorbing polymers, vermiculite, sawdust, silica-based substances, etc.) may also be included. In addition, various other conventionally known components can be added as necessary.

Specific composition examples of the exothermic composition include iron powder, reduced iron, activated carbon, alumina, silica gel, charcoal, water-absorbing polymer, sodium chloride, potassium chloride, calcium chloride, magnesium chloride, iron chloride, acetic acid, and chloroacetic acid. , water, acrylic water-absorbing polymer, CMC, bentonite, tourmaline (magnesium tourmaline), sodium tripolyphosphate, slaked lime, vermiculite, wood flour, polyethylene, polypropylene, polystyrene, etc. Preferred for use.

Examples of blending of these components include, based on the weight of the exothermic composition as 100%, 35 to 80% by weight of iron, 1 to 20% by weight of activated carbon, 1 to 10% by weight of salts, 5 to 45% by weight of water, and activated carbon. Examples include water retention agents containing 0 to 45% by weight of other water retention agents.

The exothermic composition can be produced by mixing the above-mentioned essential components and optional components selected as necessary by a known method under hypoxic or anoxic conditions. The heat-generating composition may be in any form as long as it is housed in the air-permeable bag, and may be in the form of powder, which may be further processed by a known method. For example, it may be formed into a sheet shape by rolling or into a cube shape by tabletting. Further, it may be used in any desired form such as clay, viscous, ink, cream, slurry, or liquid.

The heating element of the present invention can be manufactured, for example, as follows. The packaging material of the present invention and the second packaging material (which may be the packaging material of the present invention or another packaging material; for example, the packaging material constituting the ventilation surface) are each made of a rectangle ( For example, cut into a predetermined shape (10 to 20 cm in length and 5 to 10 cm in width). The heating element of the present invention is provided by placing the nonwoven fabric surface of the packaging material of the present invention facing downward and the heat-sealable resin layer of the second resin film layer facing upward on a table, and on top of that, a molded material smaller than the packaging material. The heat-generating composition is placed, and the resin film layer of the second packaging material is superimposed downward so as to cover the heat-generating composition, and the peripheral edge is heat-sealed at a predetermined temperature using a heat-sealing device. be able to. Alternatively, the bag can be made by stacking the packaging material of the present invention on a second packaging material with the nonwoven fabric layer on the outside, and sealing the three peripheral sides of the second packaging material using thermocompression bonding, adhesive, or other means. It can also be manufactured by applying the exothermic composition through the unsealed opening, and then sealing the opening by thermocompression bonding or the like.

Furthermore, the heating element of the present invention can be manufactured by using a rotating heat-sealing roll manufacturing machine commonly used in the industry, and carrying out the above-mentioned heat-sealing bag making and enclosing the heat-generating composition in series on a rotating roll. It can be manufactured continuously from one size of packaging material.
The rotating roll type heating body manufacturing machine forms heating bodies such as rectangular shapes so as to be connected in the longitudinal direction by continuously supplying a long packaging material and a heat-generating composition and heat-sealing them. By cutting the connected parts of the connected heating elements, a plurality of rectangular heating elements can be obtained in succession. When manufacturing the heating element of the present invention, this rotary roll manufacturing machine includes a guide for conveying the packaging material on one side and the packaging material on the other side, one or more sets of rotary heat seal rolls, and one set of cutting rolls. It is made up of. The rotary heat seal roll is provided with a substantially box-shaped recess so that it can be filled with the exothermic composition, and a seal having a width of 14 mm in the longitudinal direction and 18 mm in the axial direction is installed around the periphery of the recess. A surface is provided. Further, the cross-sectional shape of the sealing surface is formed in an uneven shape, and a radius of curvature (R) of, for example, 1 mm may be provided at the end of the sealing surface. The rotary roll manufacturing machine may further include a heat generating composition supplying means (hopper) for supplying the heat generating composition to the recesses of the heat seal roll.

The outer bag heating element is usually stored in an airtight package (outer bag) that blocks oxygen until it is used. The material and manufacture of such an outer bag are known.

Production of laminated sheet packaging <Example 1>
PET spunlace nonwoven fabric (weighing 40 g/m ² , manufactured by Hangzhou Nbond Nonwoven), LDPE resin (thickness 30 μm, manufactured by Tosoh LDPE resin, and DIC's "PEONY HP WHITE C-11186MPT" 70% titanium oxide opalescent masterbatch) (added in an amount of 10% by weight based on the weight of the LDPE resin) was laminated by the first tandem extrusion lamination method. mLLDPE resin (thickness 15 μm, manufactured by Nippon Polyethylene Co., Ltd.) was continuously laminated on the LDPE surface in the same process using a second tandem extrusion lamination method. The total light transmittance was measured using a haze meter according to the JIS K-7361-1 test method, and the average value of n=5 measurements in the width direction was taken as the total light transmittance. As a result, the total light transmittance of the laminated packaging material was 33.4%.

<Comparative example 1>
An LDPE resin (thickness 30 μm, manufactured by Tosoh Corporation) was laminated onto a PET spunlace nonwoven fabric (fabric weight: 40 g/m ² , manufactured by Hangzhou Nbond Nonwoven Co., Ltd.) using a first tandem extrusion lamination method. mLLDPE resin (thickness 15 μm, manufactured by Nippon Polyethylene Co., Ltd.) was continuously laminated on the LDPE surface in the same process using a second tandem extrusion lamination method. The total light transmittance of the laminated packaging material was 56.4%.

<Example 2>
PP spunbond nonwoven fabric (weighing 30 g/m ² , manufactured by Shandong HaiWei Hygiene New Material), LDPE resin (thickness 30 μm, Tosoh LDPE resin, DIC manufactured "PEONY HP WHITE C-11186MPT" 70% titanium oxide milk white) The masterbatch was added in an amount of 10% by weight based on the weight of the LDPE resin) and was laminated using the first tandem extrusion lamination method. mLLDPE resin (thickness 15 μm, manufactured by Nippon Polyethylene Co., Ltd.) was continuously laminated on the LDPE surface in the same process using a second tandem extrusion lamination method. The laminated total light transmittance was 36.5%.

<Comparative example 2>
LDPE resin (thickness 30 μm, manufactured by Tosoh Corporation) was laminated on a PP spunbond nonwoven fabric (fabric weight 30 g/m ² , manufactured by Shandong HaiWei Hygiene New Material) by a first tandem extrusion lamination method. mLLDPE resin (thickness 15 μm, manufactured by Nippon Polyethylene Co., Ltd.) was continuously laminated on the LDPE surface in the same process using a second tandem extrusion lamination method. The laminated total light transmittance was 71.4%.

Performance test <Test example 1>
The lamination strength between the nonwoven fabric and LDPE of each of the laminated sheet packaging materials produced above was measured as follows. A strip-shaped test piece with a width of 15 mm and a length of 150 mm was cut out, the end of the test piece was peeled off by hand, and the end of the film and the end of the nonwoven fabric were clamped. The laminate was peeled off in a direction of 180 degrees at a speed of 300 mm/min, and the average value of the values measured with a load measuring device was defined as the laminate strength.

The results are shown in Table 1.

From the results shown in Table 1, it is considered that by including the pigment in the first resin film layer, the thermal conductivity of the resin film was improved, the flow adhesiveness of the resin was improved, and the laminate strength was improved.

Measurement of heat seal strength <Test Example 2>
The heat seal strength of the laminated sheet packaging material produced above was measured as follows. As the other packaging material to be heat-sealed, the laminated sheet packaging material also produced above was used. The second resin film layer is set in the body warmer making machine so that it faces each other, and while the one laminated sheet packaging material is perforated in-line with a needle, the body warmer making machine at a speed of 5.74 m/min is used to heat the surrounding area at various temperatures. The parts were heat-sealed to produce a rectangular body warmer with a short side of 100 mm and a long side of 135 mm. Note that the sealing direction is such that the short side is the horizontal seal and the long side is the vertical seal, and the seal width is 9 mm for the horizontal seal and 7 mm for the vertical seal.
The seal strength of the heat-sealed portion as described above was measured using a tensile tester (manufactured by Aiko Engineering, MODEL 1301-D, 0113). First, each sealed portion on the four sides of a rectangular bag was cut out to a size of 15±0.5 mm×35±5 mm and used as a sample. The upper limit adjustment ring screw was set so that the chucking interval of the tensile tester was 40±5 mm. The PEAK switch on the test machine was pressed to turn on the lamp. One end (5 to 10 mm) of the sample was held in the chucking part (top) of the testing machine, and the other end of the sample was placed in the chucking part (bottom). The tensile speed was set to 300 (mm/min) and the measurement was started. The measured MAX value was recorded when sample failure or cessation of tensile motion occurred.

The results are shown in Table 2. In Table 2, "n=1" and "n=2" in the sealing strength represent the number of each vertically or horizontally sealed side of the rectangle, respectively.

From the results in Table 2, it is considered that by including the pigment in the first resin film layer, the thermal conductivity of the resin film was improved and the heat seal strength was improved. Furthermore, as shown in the results in Table 1, it is thought that the improved flowability of the resin and the improved lamination strength also contributed to the improvement in the longitudinal heat seal strength.

Claims (6)

A bag for containing a heat generating composition that generates heat in the presence of air, at least one side of which includes a nonwoven fabric layer, a first resin film layer made of a polyethylene resin containing a pigment, and a heat generating composition that does not contain a pigment. A heat-generating composition accommodating material comprising a non-breathable packaging material having a second resin film layer consisting of a sealing resin layer in this order, and at least one other surface comprising a breathable film or sheet. bag for ; and
an exothermic composition that generates heat in the presence of air contained in the bag;
A type of heating element that is not attached to clothing or the body, including The breathable film or sheet comprises a nonwoven fabric layer, a first resin film layer made of a polyethylene resin containing a pigment, and a second resin film layer made of a heat-sealable resin layer not containing a pigment in this order. The heating body according to claim 1 , which is a film or sheet made breathable by perforating a non-breathable packaging material. The heating body according to claim 1 or 2 , wherein the pigment contains titanium oxide or calcium carbonate. The heating body according to any one of claims 1 to 3 , wherein the first resin film layer is made of low density polyethylene. The heating element according to any one of claims 1 to 4 , wherein the heat-sealable resin layer is made of metallocene catalyst-based linear low-density polyethylene. The heating body according to any one of claims 1 to 5 , which is housed in an airtight outer bag.