JP2000143828A - Far-infrared-emitting sealant film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sealant film which bas the possibility of exhibiting a sufficient warming effect even under low-temperature conditions, has excellent heat sealability and seal strength, and is alleviated in adverse effects on the environment by dispersing bamboo char microparticles having a specified particle diameter. SOLUTION: A felled thick-stemmed bamboo (Phyllostachys pubeseens) is charred by heating to 1,000-1,600 deg.C and finely ground to obtain bamboo char microparticles having a specific surface area of 1,000 m2/cm3 and a mean particle diameter of 0.01-30 μm. The microparticles in an amount of 0.5-20 wt.%, desirably, 0.5-10 wt.% are added to at least one resin selected from among a polyethylene, a polypropylene, a polystyrene, an ethylene/(meth)acrylic acid copolymer, etc., and uniformly dispersed therein. The obtained mixture is extruded through an extruder having a screw diameter of 25-200 mm and a screw L/D ratio of 15-35 under conditions including an extrusion temperature of 120-125 deg.C, a die lip gap of 0.5-5.0 mm, and a blow-up ratio of 1.0-4.0 to obtain a far-infrared-emitting sealant film having a thickness of 20-250 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealant film, and more particularly, to a sealant film which exhibits a high far-infrared emissivity and far-infrared radiation intensity at a relatively low temperature of 17 to 40.degree. A sealant film that can be used. For example, by applying the sealant film of the present invention to a product such as a disposable body warmer, it is expected that the thermal effect of the disposable body warmer will be improved more continuously.

[0002]

2. Description of the Related Art Conventionally, in the field of packaging materials, a sealant film has to be used as the innermost base material of a plastic bonded packaging material, and can be processed into a bag by the heat welding property of the sealant film. Since the contents can be protected from the hygiene point of view, it is absolutely indispensable to increase the productivity at the packaging stage of various products. Therefore, functions such as anti-fogging property, anti-static property and contaminant sealing property have been added to the sealant film. However, a sealant film having a far-infrared radiation function has not been proposed so far.

On the other hand, other than the sealant film, for example, Japanese Patent Application Laid-Open No. 9-239806 proposes cellophane paper having far-infrared radiation ceramic powder and having food freshness retention properties. Further, a freshness retaining film in which fine particles of tourmaline ore are dispersed is proposed as Utility Model Registration No. 2539204.

[0004]

However, in these proposals for cellophane paper for maintaining freshness, no consideration has been given to the heat sealability and seal strength required for the sealant film, and these prior arts are not considered. It cannot be applied to a sealant film as it is.

Further, far infrared radiation ceramics are 500
Although the emissivity of far-infrared rays is relatively high under high-temperature conditions of up to 700 ° C., the emissivity of far-infrared rays is low under low-temperature conditions of 50 ° C. or less, and there is a problem that a sufficient heating effect cannot be expected. Furthermore, a plastic film in which tourmaline ore is dispersed also has a low far-infrared radiation ability, so that a thermal effect under low-temperature conditions cannot be expected.

On the other hand, seaweed charcoal and Bincho charcoal obtained by carbonizing natural products are known as materials having high far-infrared emissivity and far-infrared radiation intensity even at relatively low temperatures. The characteristics of seaweed charcoal are disclosed in JP-A-7-102249, and it is reported that the far-infrared emissivity and the far-infrared radiation intensity are high even at a relatively low temperature of 50 ° C. or lower. The effects of Bincho charcoal are well known, and high far-infrared emissivity and far-infrared radiation intensity are exhibited even at low temperatures.

[0007] However, seaweed charcoal requires a treatment with alkali when carbonized seaweed such as wakame, alame, kelp and the like to obtain seaweed char as a target material. There is. In addition, Bincho charcoal has a problem that it is not preferable in view of its effect on the environment because it is used by cutting wood such as oak, oak, and oak oak.

Further, to date, products utilizing the thermal effect of far infrared rays include supporters and disposable warmers. For example, a disposable body warmer generally has a configuration in which the content serving as a heat source is wrapped with a material obtained by laminating a nonwoven fabric and a sealant film. Are printed on the market to provide a thermal effect based on far-infrared radiation. However, the thermal effect of the packaging material has not been sufficiently exhibited.

Accordingly, the present invention can be expected to provide a sufficient heating effect even at a low temperature of 50 ° C. or less, and has good properties required for a sealant film such as heat sealability and seal strength, and has a bad influence on the environment. It is an object to provide a low far-infrared radiation sealant film.

[0010]

Means for Solving the Problems To achieve the above object, the present inventors have prepared bamboo charcoal fine powder having an average particle diameter of 0.01 to 30 μm in a predetermined film for a sealant.
It is 17 to 17 by simply dispersing uniformly at a rate of 5 to 20% by weight.
The idea was to emit far-infrared ray with high far-infrared emissivity and radiant intensity at relatively low temperature of 40 ° C, and as a result of intensive studies, the sealant film exhibited a thermal effect based on far-infrared emissivity and radiant intensity And excellent smoothness,
It has been found that it shows thickness and thinness precision and high heat seal strength,
The present invention has been completed.

That is, the far-infrared radiation sealant film of the present invention is characterized in that fine bamboo carbide having an average particle diameter of 0.01 to 30 μm is uniformly dispersed at a ratio of 0.5 to 20% by weight. I do.

According to this sealant film, the bamboo charcoal dispersed in the sealant substrate has an average particle diameter of 0.01 to
Since the thickness is 30 μm, which is sufficiently smaller than the thickness of the sealant film, and the mixing ratio is 0.5 to 20% by weight, the heat sealability and the seal strength required for the sealant film are sufficiently satisfied. In addition, bamboo charcoal is 50
Since it has a high far-infrared emissivity and far-infrared radiation intensity even at a low temperature of not more than ℃, the thermal effect by far-infrared rays can be exhibited. Furthermore, since bamboo charcoal is used,
There is no need for alkali treatment or the like, and bamboo grows quickly, so cutting it has little adverse effect on the environment.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details will be described below. In the present invention, the felled Moso bamboo is 1000-1600.
Bamboo charcoal carbonized at ℃ and pulverized into fine particles having an average particle diameter of 0.01 to 30 μm or less is used. Bamboo charcoal has a surface area of 1000 m 2 per cm 3, and about 50% of its components are composed of minerals such as potassium, calcium, magnesium, iron and zinc.

From this, bamboo charcoal has deodorant, moisture absorption, water retention,
It excels in many properties such as drainage, ventilation, animal heat, and adsorption.
In addition, a surprising value of MRA (co-bird magnetic wave) is detected compared to other substances, and it is recognized that it has properties useful for environmental improvement and purification, such as emission of negative ions. ing. In addition, seaweed charcoal and Bincho charcoal exist as materials obtained by carbonizing natural materials such as bamboo charcoal and emitting far infrared rays at a relatively low temperature. However, seaweed charcoal is made of wakame, alame,
When carbonizing seaweeds such as kelp and collecting seaweed charcoal, which is the target, it is considered to be unfavorable in terms of work because it requires treatment with alkali. In addition, Bincho charcoal is used because it is used by cutting wood such as oak, oak and upame oak, which is not preferable in view of its effect on the environment. On the other hand, since bamboo charcoal uses bamboo, which is known to grow fast, there is little adverse effect on the environment even if it is cut down, and it is rather convenient to cut bamboo in areas where rapid growth of bamboo is hindering. It may be.

The resin used as a main component of the sealant film of the present invention is polyethylene, polypropylene,
Polystyrene, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylate copolymer,
Ethylene-vinyl acetate copolymer, maleic anhydride-modified polyethylene, carboxylic acid-modified polyethylene, polyvinylidene chloride copolymer, ethylene-propylene copolymer, polypropylene-diene copolymer, ethylene-propylene-
And diene copolymers. These resins are used alone or in combination of two or more. Among these, polyethylene resins are generally preferred as sealant films in that they have properties such as heat resistance, impact strength, and abrasion resistance.

The most effective distribution ratio between bamboo charcoal and resin is such that the ratio of bamboo charcoal to resin is 0.5 to 20% by weight, preferably 0.5 to 10% by weight. If it is less than 0.5% by weight, a sufficient far-infrared effect cannot be obtained. Conversely, if it is more than 20% by weight, not only is the proportion of bamboo charcoal too large, it becomes difficult to maintain the shape of the film, but also the surface of the film becomes rough, so that air bubbles are trapped during bonding with other substrates and after heat sealing. Loses the function as a sealant film, for example, the seal strength becomes impractical. The average particle size of the bamboo charcoal fine powder is 0.01 to 30 μm, preferably 0.1 to 2 μm.
0 μm is good. The smaller the average particle size of bamboo charcoal, the better it can be dispersed and the function of the sealant film is not impaired. However, the average particle size is 0.01 μm
If it is less than 1, special processing technology is required in the pulverization of bamboo charcoal, so that it is economically burdensome to use it as a sealant. According to common sense, the thickness of the sealant film is 20
２００200 μm, and the frequently used thickness is 40-10
0 μm. Here, if bamboo charcoal powder having an average particle diameter of more than 30 μm is used, even if a relatively thick film is produced, dispersibility becomes extremely poor and fine powder comes out on the surface of the sealant base material, thus impairing the smoothness of the surface. , Loses its function as a sealant film.

As a method for producing the composition of the present invention, a general method, for example, a kneader, a Banbury mixer, a continuous mixer, or a kneader such that a polyolefin resin which is a main component of a sealant film and bamboo charcoal are in the above-mentioned mixing ratio. After uniform mixing using an extruder or the like, the mixture is pelletized using a granulator and a film can be obtained using a hot press. Further, the pellets can be melt-kneaded and extruded and formed into a film using a known molding method such as an inflation molding method, a T-die molding method, and a cooling film method, but is not limited thereto.

When the film is formed by the inflation molding method, the form of the extruder can be a generally used extruder of a film forming machine. Particularly, a screw diameter of 25 to 200 mmφ and a screw L / D are used. Fifteen
It is preferred to use an extruder of ~ 35. The extrusion conditions in the inflation molding are as follows: extrusion temperature of 120 to 250 ° C., die lip interval of 0.5 to 5.0 m.
m, preferably 1.0 to 3.5 mm, and a blow-up ratio of 1.0 to 4.0, preferably 2.0 to 3.0, to form a film having a film thickness of 20 to 250 μm.

[0019]

Next, some examples of the present invention will be described together with comparative examples.

[Example 1] Polyethylene manufactured by Sumitomo Chemical Co., Ltd. and bamboo charcoal powder having an average particle diameter of 1 µm were mixed with a tumbler mixer so that the bamboo charcoal powder was 10% by weight with respect to the polyethylene. It pelletized using the 50mm (phi) extruder made by company. Thereafter, using a blow-molding machine with a 50 mmφ extruder manufactured by Modern Machinery Co., Ltd., a blow ratio of 2.55 and a film thickness of 100 μm × width of 40
It was molded at 0 mm with a throughput of 40 kg / h per hour. The radiant intensity of far-infrared rays and the radiant intensity of the black body of the sealant film of this example thus produced were measured by a Fourier transform infrared spectroscopic altimeter (FTlR), and the results are shown in FIG. The measurement conditions were such that the black body and the film sample were kept at 25 ° C., and the wavelength of both was 4.0 to 24.0 μm.
Was measured to determine the emission intensity of both. Note that the radiation intensity is (WXsr-1 × cm-2) ×
10 (WXsr-1 × cm−2 represents radiance). Further, the ratio of the radiation intensity of the example and the radiation intensity of the black body obtained above was set as the emissivity (%), and the results are shown in FIG. As is clear from the results of FIG.
Despite the low temperature of 5 ° C, the wavelength stably ranges from 6.0 to 2
A good result was obtained that far infrared rays of 4.0 μm were emitted at an emissivity of 90% or more.

Next, as described above, it was observed that at room temperature of 25 ° C., high far-infrared radiation intensity and emissivity were exhibited. Therefore, the sealant film of this embodiment was applied to a part of the human body to examine the thermal effect. And took a thermogram. The instrument used for the thermogram measurement is 6P62 manufactured by NEC Corporation. As a result, it is possible to raise the temperature of a part of the human body to which the sealant film of the present embodiment is applied for about 30 minutes and the surrounding area thereof by about 0.8 ° C., and to remove the sealant film of the present embodiment for about 3 minutes. But it was confirmed that the temperature was still maintained, the thermal effect,
It fulfilled the performance as a film with a heat retaining effect.

Further, in order to confirm the function as a sealant film, heat sealability was observed. The film of this example was heat-sealed using a heat sealer manufactured by Tester Sangyo Co., Ltd. under the conditions of 2 kgf / cm 2 and 0.5 seconds, and the temperature dependence of the seal strength was measured using an autograph manufactured by Shimadzu Corporation. As a result, heat seal temperature 1
At 20 ° C., the seal strength showed a width of 1 kgf / 15 mm, and the performance showed no problem in practical use.

In the laminating process, the sealant film of this example and a commercially available nylon film were bonded with a polyurethane adhesive manufactured by Dainippon Ink and Chemicals, but the process could be performed without air bubbles. The heat seal strength of the laminated product was 5 kgf / 15 mm width, which was equivalent to the strength of a general sealant film.

Example 2 The mixing ratio of bamboo charcoal powder to the polyethylene of Example 1 was changed from 10% by weight to 20% by weight, and heat sealability and laminating property were evaluated. At a film thickness of 100 μm, there was no practical problem and sufficient heat seal strength and laminating property were exhibited.

Example 3 The average particle size of Example 1 was 1
Instead of the bamboo charcoal powder of μm, a bamboo charcoal powder having an average particle diameter of 30 μm was used to evaluate heat sealability and lamination processability. At a film thickness of 100 μm, there was no problem in practical use, and a part of the bamboo charcoal powder was clogged in the filter of the extruder, and an increase in extrusion pressure was observed. However, sufficient heat seal strength and laminating workability were exhibited.

Example 4 A bamboo charcoal powder having an average particle diameter of 20 μm was added to an ethylene vinyl acetate copolymer (vinyl acetate content: 5% by weight) manufactured by Sumitomo Chemical Co., Ltd. at 1% by weight based on the ethylene vinyl acetate copolymer. After mixing so that the ratio of
The molding was performed in the same manner as in Example 1. The far-infrared radiation intensity and the radiation intensity of the black body of this sealant film were measured in the same manner as in Example 1, and the wavelength was stably from 6.0 to 24.0 μm despite the low temperature of 25 ° C. Radiated far infrared rays at an emissivity of 90% or more.

The function as a sealant film was confirmed in the same manner as in Example 1. As a result, the heat seal temperature 11
At 5 ° C., the sealing strength was 1 kgf / 15 mm width, and the performance showed no problem in practical use.

In the laminating process, the sealant film of this example and a commercially available nylon film were bonded with a polyurethane adhesive manufactured by Dainippon Ink and Chemicals, but the process could be performed without air bubbles. The heat-sealing strength of the laminated product was 3.5 kgf / 15 mm width, which was practically no problem as a sealant film.

Comparative Example 1 Polyethylene manufactured by Sumitomo Chemical Co., Ltd. was blown at a rate of 40 kg / h at a blow ratio of 2.55 and a film thickness of 100 μm × 400 mm in width using an inflation molding machine with a 50 mmφ extruder manufactured by Modern Machinery. Molded at throughput. This sealant film does not emit far-infrared rays having a wavelength of 6.0 to 24.0 μm,
The thermogram was measured in the same manner as in Example 1. As a result, the temperature of a part of the human body to which the sealant film was applied was raised by about 0.1 ° C. for about 30 minutes. Has returned.

Comparative Example 2 Bamboo charcoal powder having an average particle diameter of 1 μm was mixed with polyethylene manufactured by Sumitomo Chemical Co., Ltd. so that the ratio of the bamboo charcoal was 40% by weight with respect to the polyethylene, and molded in the same manner as in Example 1. . No problem was found in the radiation intensity and emissivity of this sealant film in the far-infrared rays, but not only the strength of the film itself was too low due to too much bamboo charcoal, but also the sealing strength of 0.2 kgf at a heat sealing temperature of 120 ° C. / 15 mm width, which was considerably lower than the practical level, and was bonded to a commercially available nylon film, but the surface of the film was rough, so that air bubbles were mixed in and lost its function as a sealant film.

Comparative Example 3 Bamboo charcoal powder having an average particle diameter of 60 μm was mixed with polyethylene manufactured by Sumitomo Chemical Co., Ltd. so that the ratio of the bamboo charcoal was 5% by weight with respect to the polyethylene, and molded in the same manner as in Example 1. . No problem was found in the far-infrared radiation intensity and emissivity of this sealant film, but because the particle size of bamboo charcoal was too large, the dispersibility was extremely poor and not only the film itself was weak, but also fine powder Since it comes out on the surface of the sealant substrate, it impairs the smoothness of the surface, and the sealing strength at a heat sealing temperature of 120 ° C. is 0.
At a width of 3 kgf / 15 mm, it was considerably lower than the practical level, and was bonded to a commercially available nylon film. However, the film surface was rough, so that air bubbles were mixed in and lost its function as a sealant film.

[Comparison of Examples and Comparative Examples] As described above, according to each example, bamboo charcoal powder having an average particle diameter of 1 to 30 μm is uniformly mixed in a sealant substrate at a mixing ratio of 1 to 20% by weight. The sealant film dispersed at 17 to 40 ° C
Under such a relatively low temperature condition, a high far-infrared emissivity and a far-infrared radiation intensity are exhibited, and it is understood that a sufficient thermal effect is exhibited. Therefore, for example, by using it as the innermost layer base material of the packaging material of the disposable body warmer, the sustainability of the thermal effect of the disposable body warmer can be enhanced.

On the other hand, if bamboo charcoal powder is mixed as much as 40% by weight, the sealing strength becomes insufficient and the average particle diameter is 60 μm.
It can be seen that even when bamboo charcoal powder having a relatively large particle diameter is mixed, the sealing strength becomes insufficient. From this, it is considered good to disperse bamboo charcoal powder having an average particle diameter of 30 μm or less in the sealant base material at a mixing ratio of 20% by weight or less.

[0034]

From the above results, according to the present invention, by mixing bamboo charcoal into a sealant film, a high far-infrared emissivity, a radiation intensity and a thermal effect based on far-infrared radiation, which could not be obtained conventionally, can be obtained. It can be exhibited at a relatively low temperature of 17 to 40 ° C., and can satisfy various properties required for a sealant film such as seal strength. In addition, by using bamboo charcoal, environmental issues can be considered.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the wavelength of radiation heat and the radiation intensity of Example 1 and a black body at 25 ° C.

FIG. 2 is a graph showing the relationship between the wavelength of radiant heat and the emissivity of Example 1 at 25 ° C.

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Claims (1)

[Claims] 1. A far-infrared radiant sealant film comprising finely divided bamboo carbide having an average particle diameter of 0.01 to 30 μm uniformly dispersed in a proportion of 0.5 to 20% by weight.