JP3350635B2 - Storage bag for ventilating exothermic composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates, the heat-sealing properties, uniformity of fluid transmission, of the preferred storage bag in the housing of the heating element or the like using the porous fill beam having excellent stability in quality.

[0002]

2. Description of the Related Art Conventionally, as a porous film based on a polyethylene resin, a composition in which a polyester resin and an ethylene copolymer are blended with a polyethylene resin, and an inorganic filler is blended if necessary. Films which have been formed and stretched have been known (JP-A-6-298977, JP-A-4-142341).

[0003] However, there is a problem that the fusibility such as hot tack property and heat sealing property is poor, and particularly the composition containing an inorganic filler has poor fusibility. Incidentally, there is a use of the porous film as a material for forming a heating element storage bag in a disposable body warmer or the like. This is because polyethylene containing no halogen is excellent in hygiene and the like.

[0004] In the above, from the viewpoint of manufacturing efficiency and the like, a method of bonding a porous film and another material to form a bag by a fusion method such as a heat sealing method or an ultrasonic embossing method in forming a storage bag. Generally employed, in this case, since the porous film has poor fusibility, a large amount of defective fusion products such as partial peeling are generated, which causes a problem of poor yield.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a method for heat sealing and the like, which satisfies the basic performance of a porous film, such as gas or liquid, which is required to have excellent permeability and uniformity of fluid permeation. Ventilation made of polyethylene-based porous film with excellent adhesion and excellent adhesion strength by fusion
An object is to obtain a storage bag for a heat-generating composition .

[0006]

The present invention relates to at least linear low-density polyethylene (metallocene linear low-density polyethylene).
Excluding) and MFR at a density of 0.85 to 0.93 g / cm ³
From 1 to 25 g / 10 min metallocene linear low-density polyethylene, a composition containing an inorganic filler as a component, not a polyester resin, and, if necessary, an ethylene copolymer as a component. there is provided a storage bag ventilation exothermic composition characterized by comprising a bag having made a multi-porous fill beam Do that from stretching of the film at least on one side.

[0007]

According to the present invention, since a film-forming polymer component containing no polyester resin by a combination of a non-metallocene linear low-density polyethylene and a metallocene linear low-density polyethylene is used, the pores formed by the stretching treatment are reduced. Even if it contains a non-fusible inorganic filler that functions as a forming material, it shows good fusibility and exhibits excellent hot tack strength (adhesive strength in the heated state immediately after fusing) and heat seal strength. ,
In addition, it is possible to obtain a polyethylene-based porous film having excellent fluid permeability and uniformity of the fluid permeability.

Accordingly, the above-mentioned porous film is excellent in bonding strength and excellent in reliability of the bonding portion by a fusion bonding method.
The storage bag of breathable exothermic composition good yield, Ru can be efficiently formed.

[0009]

Breathable exothermic composition according to the present invention embodiments of the invention] Osamu
Bags must be made of at least linear low-density polyethylene (metallo
(Excluding styrene linear low-density polyethylene) .
A metallocene linear low-density polyethylene having an MFR of 85 to 0.93 g / cm ³ and an MFR of 1 to 25 g / 10, an inorganic filler as a component, and a polyester resin as a component; Porous film composed of a stretched product of a film composed of a composition containing a copolymer
It uses a system .

As the linear low-density polyethylene, an appropriate one comprising a copolymer of ethylene and an α-olefin such as butene, hexene or octene can be used. Linear low density polyethylene (excluding metallocene linear low density polyethylene)
Can be used.

The metallocene linear low-density polyethylene is
Improvement of kneadability and uniform dispersibility of inorganic filler, improvement of processability into film, improvement of film strength by improvement of compatibility between linear low-density polyethylene and inorganic filler, suppression of stretching unevenness and stretching It is used for the purpose of improving the stretching processability such as the uniformization of molecular orientation at the time and the improvement of the fusion property, especially the fusion property with different materials.

In the present invention, from the above-mentioned point of view,
Density is 0.85 to 0.93 g / cm ³ and MFR is 1 to 25
g / 10 min metallocene linear low density polyethylene is used. In particular, from the viewpoint of forming a uniform film by an extrusion molding method, etc., uniformity of fluid permeability and fusibility of the obtained porous film, or rupture prevention at the time of fusing due to a decrease in film strength, the MFR is Those having 2 to 20 g / 10 min, especially 3 to 10 g / 10 min, are preferred. Note that the above MF
R is based on a melting temperature of 190 ° C. according to ASTM D-1238.

By using the above-mentioned metallocene linear low-density polyethylene in combination, it is possible to use a low-density polyethylene-based or ethylene-methacrylate-based copolymer, a metallocene polyethylene-based or ethylene-vinyl acetate-based copolymer, and other materials such as a film. Good fusion treatment can be performed.

The proportion of the metallocene linear low-density polyethylene used is preferably 5 to 100 parts by weight per 100 parts by weight of the linear low-density polyethylene in view of film strength, good fluid permeability and good fusibility. 7 to 80 parts by weight, especially 1
0 to 50 parts by weight is preferred.

In the present invention, a part of the metallocene linear low-density polyethylene can be substituted with an ethylene copolymer, if necessary, for the purpose of improving the adhesion to different materials. Therefore, in this case, the use ratio of the metallocene linear low-density polyethylene satisfies 5 to 100 parts by weight per 100 parts by weight of the above-described linear low-density polyethylene based on the total amount with the ethylene-based copolymer. Is preferred. Further, the substitution ratio of the ethylene copolymer is preferably 70% by weight or less, more preferably 60% by weight or less, from the viewpoint of maintaining the combined effect of the metallocene linear low-density polyethylene.

As the ethylene-based copolymer, one or more suitable copolymers of ethylene and another vinyl-based monomer can be used. Above all, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methacrylic acid copolymer and the like can be preferably used. In particular, the content of monomer components other than ethylene, such as vinyl acetate, ethyl acrylate, and methacrylic acid, is 5 to 35% by weight, particularly from the viewpoint of the effect of improving the fusion property and the heat resistance for maintaining the film strength. 10 to 33% by weight, especially 19 to 29% by weight, and an MFR of 1 to 25 g /
An ethylene copolymer of 10 minutes is preferably used.

As the inorganic filler, for example, an appropriate one such as calcium carbonate, talc, clay or kaolin, silica or barium sulfate, kaolin or aluminum hydroxide, zinc oxide or calcium oxide, titanium oxide or mica may be used. Any known porous film can be used.

The average particle size of the inorganic filler may be appropriately determined according to the fluid such as gas or liquid to be permeated. Generally, from the viewpoint of preventing the pore size from becoming excessively large and preventing the dispersibility from being reduced due to aggregation, 30 μm or less, particularly 0.05 to 20 μm,
In particular, 0.1 to 10 μm is preferable.

The proportion of the inorganic filler used is such that a low content prevents a decrease in film strength and fluid permeability, a high content prevents a kneading property and a moldability from deteriorating, and prevents a decrease in the fusing property and the composition. From the viewpoint of preventing the working environment from deteriorating due to falling off, 5 parts per 100 parts by weight of linear low density polyethylene
0 to 300 parts by weight, especially 70 to 250 parts by weight, especially 10
0 to 200 parts by weight is preferred.

The composition for forming a film can be obtained by mixing the components in an appropriate manner. In this case, a mixer such as a mixing roll, a Banbury mixer, a twin-screw kneader, or a Henschel mixer is preferable in terms of film formability due to uniform mixing of components.

In the above-mentioned mixing, a softening agent can be blended if necessary. The compounding amount of the softening agent is preferably 25% by weight or less of the total amount of the metallocene linear low-density polyethylene and the ethylene-based copolymer from the viewpoint of preventing the strength of the obtained porous film from being reduced. As the softener, a suitable one such as a petroleum-based process oil or liquid paraffin, a low-viscosity material such as an aliphatic oil or a low-molecular-weight plasticizer, or a high-viscosity material such as polybutene, a low-molecular-weight polyisobutylene, or a liquid rubber is used. Can be used. Among them, those having a molecular weight of 1,000 to 30,000 based on the number average molecular weight and the like are preferable from the viewpoint of film strength and the like.

If necessary, the composition may contain appropriate additives such as an antioxidant, an ultraviolet stabilizer, an antistatic agent, a pigment, a lubricant and a fluorescent agent which may be added to the porous film. can do.

The production of the porous film can be obtained by forming the composition into a film by an appropriate method such as a casting method by solution or a molding method by melting, and then stretching the film uniaxially or biaxially. it can. Therefore, a porous film can be obtained by applying a known method. Above all, from the viewpoint of production efficiency and the like, a method in which the composition is melted and formed into a film by an inflation molding method or a T-die molding method is preferred.

The stretching method for making the film porous is not particularly limited. For example, an appropriate stretching method such as a roll stretching method or a biaxial stretching method such as a simultaneous or sequential method can be applied. The stretching ratio is 100 to 600 in the case of uniaxial stretching from the viewpoints of strength and pore size or fluid permeability of the obtained porous film, uniform stretchability and prevention of breakage.
%, Preferably 200 to 500%, particularly 250 to 450%, and in the case of biaxial stretching, 10 to 400%, 15 to 3
50%, particularly preferably 20-300%.

After the stretching treatment, the porous film may be subjected to an acid, an alkali,
Alternatively, the inorganic filler can be eluted with an appropriate eluent such as water.

The storage bag of the present invention is a bag formed by using the above-mentioned porous film on the entire surface or on one surface. The storage bag can be in a conventional bag form such as a bag formed by joining the ends of a film. The bonding of the film ends and the like can be performed by an appropriate method, but in the present invention, the fusion method is preferably applied from the viewpoint of bag manufacturing efficiency and the like. For the fusion, an appropriate method such as a heat sealing method or an ultrasonic embossing method can be adopted.

The above-mentioned storage bag can be preferably used, for example, for storing a breathable heat-generating composition forming a disposable warmer or the like by utilizing the air permeability of the porous film. In order to form a disposable body warmer or the like, from the viewpoint of appropriate heat build-up of the heat-generating composition based on air permeability, it has an average pore diameter of 0.1 to 10 µm and a water vapor permeability of 100 to 1500 g / m ² · day. A porous film can be preferably used. When the storage bag is formed of the porous film and another material, an appropriate material such as the film exemplified above may be used as the other material.

[0028]

EXAMPLE 1 density 0.93 g / cm ^3, linear low-density polyethylene 100 parts of MFR2.1g / 10 min (parts by weight, hereinafter the same), density 0.910g / cm ^3, MFR5.0g / 40 minutes of metallocene linear low-density polyethylene for 10 minutes, average particle size 2 μm
Of 150 parts of calcium carbonate (treated with fatty acid) and 1.6 parts of stearic acid are further mixed and kneaded with a twin-screw kneader (TEM-50, manufactured by Toshiba Machine Co., Ltd.), and then granulated by an ordinary method. Using the pellets, a film having a thickness of 140 μm is formed at a melting temperature of 230 ° C. by a single screw extruder, and is stretched by a roll stretching machine at a stretching speed of 40 m / min and a stretching ratio of 300%. Heat-generating composition
A porous film for a storage bag was obtained.

Example 2 20 parts of a metallocene linear low density polyethylene were mixed with MF
According to Example 1, except that R was replaced with an ethylene / ethyl acrylate copolymer (ethyl acrylate content: 25% by weight) of 5.0 g / 10 min .
To obtain a porous film.

Example 3 20 parts of a metallocene linear low-density polyethylene were mixed with MF
A porous film for a storage bag of a ventilating heat-generating composition was obtained in the same manner as in Example 1 except that the ethylene-vinyl acetate copolymer (vinyl acetate content: 19% by weight) was substituted by R 3.0 g / 10 min. .

Example 4 20 parts of a metallocene linear low-density polyethylene were mixed with MF
R2.8g / 10 min ethylene-methacrylic acid copolymer (methacrylic acid content 19 wt%) addition was replaced with 40 parts in accordance with Example 1, a multi for storage bag breathable exothermic composition <br / > A porous film was obtained.

Comparative Example 1 A porous film for a storage bag of a ventilation heat-generating composition was obtained in the same manner as in Example 1 except that the metallocene linear low-density polyethylene was not used .

Comparative Example 2 MFR was used in place of metallocene linear low-density polyethylene.
Except for using 40 parts of an ethylene / propylene / diene terpolymer of 2.0 g / 10 min, the same procedure as in Example 1 was followed to generate air.
A porous film for a storage bag of the thermal composition was obtained.

Comparative Example 3 20 parts of the metallocene linear low-density polyethylene was
Aeration was performed according to Example 1, except that the mixture was replaced with 4-cyclohexanedimethanol-modified polyethylene terephthalate.
A porous film for a storage bag of the thermal composition was obtained.

Evaluation Test The following characteristics were examined for the porous films obtained in Examples and Comparative Examples. The moisture permeability was examined by a cup method based on JIS L 1099.

Hot tack strength Using a heat sealer, 120 ° C., 10 kg / cm ² , 1
It was heat-sealed with an ethylene / vinyl acetate film (EVA) or polyethylene film (PE) having a thickness of 50 μm under the condition of seconds, and T-peel strength was measured immediately after the sealing (peeling speed 300 mm / min).

Heat sealing strength After sealing, according to the hot tack strength test, 24 hours at room temperature.
The T-peel strength of the sample left for a while was measured.

The above results are shown in Tables 1 and 2.

[Table 1]

[0039]

[Table 2]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hirohito Onishi 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (56) References JP-A-5-162251 (JP, A) JP JP-A-7-118431 (JP, A) JP-A-2-261846 (JP, A) JP-A 9-176400 (JP, A) Plastics Data Book, Japan, Industrial Research Institute Co., Ltd., December 1, 1999 , Page 351 (7) 1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65D 30/02 C08J 9/00

Claims (3)

(57) [Claims] (1) at least a linear low-density polyethylene (meth)
Excluding tarocene linear low-density polyethylene), having a density of 0.85 to 0.93 g / cm ³ and an MFR of 1 to 25 g / 10
And min metallocene linear low density polyethylene, an inorganic filler and components, and a bag body having a multi-porous film Do that from stretching of films made from compositions without the polyester resin as a component at least one side Specially become
A storage bag for the aerated heat-generating composition . 2. The method according to claim 1, wherein the porous film is formed.
Ventilation heating the composition to have a ethylene copolymer also component
Storage bag for the acidic composition . 3. The porous film according to claim 1 or 2,
Forming composition contains a linear low density polyethylene per 100 parts by weight, 5 to 100 parts by weight in total of the metallocene linear low density polyethylene and ethylene copolymers, the inorganic filler 50-300 parts by weight are those, ventilation heating said ethylene copolymer is an ethylene-vinyl acetate copolymer is one or more ethylene-ethyl acrylate copolymer or ethylene-methacrylic acid copolymer
Storage bag for the acidic composition .