JPH0429840A - Gas permeable packaging material and packaged body therewith - Google Patents

Abstract

PURPOSE:To greatly improve the gas permeability by preparing a packaging material with a structure wherein a hot-melt-type synthetic resin is partly positioned between a fine porous film or a non-woven fabric type product and a gas permeable and porous synthetic resin film. CONSTITUTION:A synthetic resin (c) with a m.p. or lower of a gas permeable and porous synthetic resin film (b) are partly positioned between a finely porous film or a non-woven fabric type product (a) with a pore diameter of 50mum or smaller and a gas permeability measured by means of Gurley method of 0.1-10,000 sec/100 cc and the film (b) with a m.p. of that of (a) or lower to obtain a gas permeable packaging material wherein (a), (b) and (c) are integrated in a body by adhering (a) with (c) and (c) with (b). The finely porous film (a) is a gas permeable fin porous film prepd. by making a polyolefin resin such as polyethylene and polypropylene wherein an inorg. filler is mixed into a film and removing the inorg. material by a method such as extraction method.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a novel packaging material for desiccants, desiccants, oxygen scavengers, freshness-preserving agents, deodorizing agents, fragrances, etc., and packages thereof. .

(Prior Art) Packaging materials that require air permeability or moisture permeability, such as household products that use calcium chloride as a desiccant agent, or packaging materials for oxygen absorbers used to preserve foods, etc., have conventionally been made of polyethylene, Microporous membranes made by mixing inorganic materials such as calcium carbonate and fine fillers with polyolefin resins such as polypropylene to form a thin film, and removing the inorganic materials, or flash films made from polyolefin resins such as polyethylene.
A microporous nonwoven fabric obtained by hot roll compression bonding of a laminate of reticular fibers obtained by a spinning method,
Coating with a dispersion of spherical or powdered hot melt adhesive, or (2) The heat-sealing surface of a hot melt resin film with holes made with a needle or the like is used as the packaging material.

In method (2), after coating with a dispersion of spherical or powder hot melt adhesive, drying is performed with hot air, but slight fluctuations in temperature, time, and air volume may affect the degree of melting of the hot melt adhesive. Therefore, it is very difficult to control the air permeability of a porous membrane or nonwoven fabric to a desired range.

Furthermore, the hot melt adhesive does not melt when drying at a low temperature for a short time, and easily peels off and falls off from the microporous membrane or nonwoven fabric. The powdered hot melt adhesive loses its shape,
It fills the pores of a microporous membrane or non-woven material, drastically reducing its air permeability.

In the method (2), for example, as described in Utility Model Application No. 55-89576, in order to supplement the strength of the packaging material, a hot-melt perforated film is heat-sealed. By making holes, the strength of the film decreases, and if large holes are made, the strength of the heat-sealed surface after being made into a packaging material decreases, or the powder, etc. inside the package may leak. Furthermore, if a small number of pores are formed in the film, the air permeability and moisture permeability of the microporous membrane or nonwoven fabric will be inhibited, making it difficult to obtain the desired packaging material.

(Problems to be Solved by the Invention) The present invention solves the problems of the above-mentioned prior art by using a microporous membrane or a nonwoven fabric (a) using a hot melt adhesive (c).
The purpose of this invention is to solve the problem of reducing the air permeability of a microporous membrane or nonwoven fabric (a) due to the hot-melt perforated film (c) having small or few holes.

(Means for Solving the Problems) In order to solve the problems of the prior art described above, the present invention provides:
．． 1 to 10,000 seconds/100 cc and a perforated synthetic resin film having a lower melting point than (b) and (a) and having air permeability, (c ), (b), where a synthetic resin with a lower melting point than that of (b) is partially placed, and (a) and (c), (c) and 0)) are bonded together (a), (b), and (c). Provides an integrated breathable packaging material. In addition, (1) A breathable packaging using all or part of the above-mentioned breathable packaging material, with the (a) side as the outer surface, containing a solid inside, and heat-sealing the periphery to prevent the solid from leaking. He also provides his body.

Furthermore, the present invention provides: (1) The microporous membrane or nonwoven fabric material (a) is obtained by removing the inorganic material from a polyolefin resin film such as polyethylene or polypropylene blended with an inorganic material such as calcium carbonate or a fine filler. The microporous membrane obtained is also a laminate of polyolefin fibers obtained by a flash spinning method.
is made from polyethylene, ethylene-vinyl acetate copolymer resin, ethylene-acrylate copolymer resin, ethylene-methacrylic acid copolymer resin, ionomer resin, polyamide resin, modified resins thereof, or mixtures of two or more of the above resins. It is also characterized by the fact that the synthetic resin (c) is arranged in dots, or in the form of lines or grids parallel to the plane (a). be.

The present invention will be explained in detail below.

The microporous membrane (a) in the present invention includes polyethylene mixed with inorganic materials such as calcium carbonate and fine fillers;
This is an air-permeable, microporous membrane in which a polyolefin resin such as polypropylene is formed into a membrane according to a conventional method, and then the inorganic material is removed by means such as an extraction method.

In addition, the nonwoven fabric (a) in the present invention refers to a laminate of three-dimensional network fibers obtained by a flash spinning method from a resin raw material mainly composed of polyolefin resins such as polyethylene and polypropylene. This is an air-permeable nonwoven fabric obtained by partially self-fusing the fibers using a heated roll at a temperature close to the melting point of .

Microporous membrane or nonwoven fabric used in the present invention (a)
has a pore diameter of 50μ or less, preferably 20μ or less. If the pore size is larger than 50μ, there is a risk of leakage if the solid inside the packaging material is powder. In particular, when the pore size is 20 μm or less, it is effective in preventing liquid leaching from the packaging material after moisture absorption and deliquescence when the powder uses a moisture absorbent such as calcium chloride.

In addition, the Gurley method air permeability is 0.1 to 10,000 seconds/1
00 cc, preferably 1-5.000 seconds/100cc
It is. At 0.1 seconds/100 cc or more, there is a risk of leakage if the solid inside the packaging material is a powder, and there is also a risk of liquid leaching if the solid is fibrous material impregnated with a liquid such as perfume. In addition, if it is 10,000 seconds/100 cc or more, the air permeability is low and is not suitable for the purpose of the present invention.

Synthetic resin film (b) or (c) in the present invention
is polyethylene, ethylene-vinyl acetate copolymer resin, ethylene-acrylate copolymer resin, ethylene-methacrylic copolymer resin, ionomer resin, polyamide resin, modified resins thereof, or mixtures of two or more of the above resins. It is made of a material selected from the group consisting of: and may contain known additives such as a tackifier, a plasticizer, and an antioxidant.

Here, these modified resins include polyethylene, ethylene-vinyl acetate copolymer resin, ethylene acrylate copolymer resin, ethylene-methacrylate copolymer resin, and ionomer resins that contain other olefinic compounds. It is a resin that is copolymerized (grafted) or (grafted) with other copolymerizable functional compounds, or modified with a functional compound, or for polyamide resins, it is a resin that is modified with other copolymerizable functional compounds, such as polyamideimide, etc. It is a resin modified by co-condensing condensable monomers, etc., and includes these modified resins that are known per se.

The method for forming holes in the synthetic resin film (b) used in the present invention is not particularly limited, but may be formed mechanically using a cloth, or by heating the tip of a needle to a temperature higher than the melting point of the synthetic resin film (b). Examples include a method of contacting and melting the material, and various arbitrary methods may be employed.

The size of the pores in the synthetic resin film (b) is not particularly specified, but if the pores are large, the peel strength after heat sealing may be If the pore size is smaller, it is difficult to obtain the intended packaging material with air permeability.

Preferably, the diameter is 0.2 to 2 mm.

Furthermore, it is preferable that the pore size of the synthetic resin film (b) be larger than that of the microporous membrane or nonwoven material (a) from the viewpoint of air resistance and air permeability of the resulting packaging material. Therefore, a perforated synthetic resin film in which holes are made mechanically or by thermal melting as described above can be preferably used.

Furthermore, if the number of holes in the synthetic resin film (b) is small, it is difficult to obtain a breathable packaging material, and if it is large, it lacks strength and is difficult to process. Preferably, it is 1 to 10 pieces/crR.

The pore diameter and number of pores of the synthetic resin film (b) can be easily determined according to the air permeability of the microporous membrane or nonwoven fabric (a) and the desired air permeability required for use as a packaging material.

The melting point of the synthetic resin film (b) is lower than that of the microporous membrane or nonwoven fabric material (a), preferably 5° C. or more lower.

The melting point of the synthetic resin (c) is lower than that of the synthetic resin film (b), preferably 5° C. or more lower.

In the present invention, a partially disposed synthetic resin (c) is interposed between a microporous membrane or a non-woven fabric (a) and a synthetic resin film (b) to combine (a) and (b). It is necessary not to bond directly. In order to integrate (a), (b), and (c) in this way, the (c) side must be melted, but
In order to thermally fuse (a) and (b) without melting, each (
It is preferable that there is a temperature difference of 5° C. or more between the melting points of a), (b), and (c).

In order to make the breathable packaging material of the present invention into a package, when the surface (b) is the inner surface and the solid is contained inside and the surroundings are heat-sealed, the material is thermally compressed from the surface (a) using a heat seal bar or the like. (a) without causing damage such as melting to the (a) side.
, (c), (b), (b), (c), (a) in this order, or (a), (c), (b), (other materials) in this order. In this case, the melting point of the microporous membrane or nonwoven material (a) is higher than that of the synthetic resin film (a).
It is more preferable that the temperature is lower than °C.

In the present invention, the partial positioning of (c) between (a) and (b) means that (c), which is a powder (including spherical shape), is scattered on the surface of (a) that is spread and travels. Methods include applying a tod-like shape to the (a) surface or (b) surface by intermittent jetting using the pressurized air of (c) heated by an applicator, continuous spraying, linear spraying, or dot-like application using a gravure roll, Any method such as linear or grid-like application may be used, and after applying to the (a) side or (b) side of (c), (a)
(a), (c), ( c) and (
(a), (c), and (b) are integrated by thermal bonding between (b) and (b).

The breathable packaging material obtained by the above method is filled with chemicals such as deodorizers and insect repellents using a vertical or horizontal pillow type packaging machine or other packaging machine with (a) as the outer surface. death,
Heat seal.

A variety of methods are used for heat sealing, including bar sealing, impulse sealing, and ultrasonic sealing.

Heat sealing conditions such as temperature, pressure, time, etc. are (a), (
It can be determined as appropriate depending on the thermal properties of the materials b) and (c), or in the case of partial use of the breathable packaging material of the present invention, also taking into consideration the thermal properties of other materials.

In this way, the breathable packaging of the present invention is obtained.

(Function) In the case of the conventional method, that is, in the case of a breathable packaging material made by directly adhering (a) and (b), only the part a in contact with the hole 1 becomes breathable, as shown in FIG. In other words, air permeability decreases.

However, in the case of the breathable packaging material of the present invention, as shown in FIG. The passing gas moves freely between parts a and b, and
You can enjoy breathability over the entire area.

In other words, even if the number of pores in part b is small and the pore diameter is small, the pores made by mechanical or thermal melting methods, for example, are smaller than the pore diameter of the microporous membrane or nonwoven fabric (a). Because of the large size and low air resistance of the pores, packaging materials constructed according to the invention are more breathable than packaging materials obtained by conventional methods.

Next, use this packaging material partially (see Figure 2) or use the entire packaging material (see Figure 3), place the solid with the b side facing inside, and heat seal by heat-sealing the surrounding area. Form part 2. During thermal fusion, a small amount of C is melted by pressing the surrounding heat-sealed portion 2 and is buried in a large amount of B on the entire surface, sealing the solid inside without any gaps. Moreover, the parts other than the surrounding heat-sealed part 2 are not affected by the thermocompression bonding and remain breathable like the packaging material of the present invention.

The present invention will be explained below with reference to Examples and Comparative Examples.
These do not limit the scope of the invention.

(Example 1) A laminate of three-dimensional network fibers of polyethylene obtained by the flash spinning method was thermocompressed using a hot roll at 137°C, and the maximum pore diameter was 7μ, the average pore diameter was 3μ, and the Gurley method air permeability was 20 seconds/ 100 cc, basis weight 50g/po, thickness 16
A non-woven fabric (a,) (manufactured by Asahi Kasei Kogyo ■, Luxar H@) was obtained.

The rolled (a,) is spread out, and a layer of ethylene-vinyl acetate copolymer resin (melting point 85°C) is placed on (al).
1. Powdered resin (c1) with a diameter of 220μ (manufactured by Asahi Kasei Kogyo ■,
PAK-X309@) was sprayed at 7g/ITf, and then a melting point of 9 containing mainly ethylene-vinyl acetate copolymer resin was applied.
A film (b, ) (manufactured by Mitsui Petrochemical Industries ■, made from Evaflex [F]) with a thickness of 25μ, a pore diameter of 1am + φ, and a number of holes of 1/d was placed on top of (c+) at 3°C and heated to 90°C. Pass it between the metal roll and rubber roll,
By melting only the surface layer of (c+), (al), (c), (
c3) and (bl) were thermally fused.

(Comparative Example 1) In Example 1, (c1) was not used, and (aI) and (
bl) were stacked and passed between a metal roll and a rubber roll heated to 95°C to bond (al) and (bl). Due to the short time of passage, there was no porosity formation in (bl).

(Example 2) A laminate of three-dimensional network fibers of polypropylene obtained by the flash spinning method was thermocompressed using a hot roll at 160°C, and the maximum pore diameter was 10μ, the average pore diameter was 5μ, and the Gurley method air permeability was 5 seconds/100. A non-woven fabric (a) (manufactured by Asahi Kasei Kogyo ■, Luxar P ■) having a thickness of 220 μm and a melting point of 165° C. was obtained.

Ionomer resin (c
) (manufactured by Mitsui Petrochemical Industries ■, Chemipearl ■), (c
2) 5III11 using rotary screen on top
The thickness of the ionomer resin after being applied in diagonal lines with a width of 2 mm and dried at 90°C is 1°Oμ.

Next, an ethylene-methacrylic acid copolymer resin having a melting point of 100°C, a thickness of 20μ, and a pore size of 0. A film (bz) with 3 + mnφ and 10 holes/ctj (manufactured by Mitsui Petrochemical Industries ■, made from Nucrel ■) was layered on top of (c2) and passed through hot air at 95°C to form the shape of (c2). While holding them, (c2) and (c2) and (c2) and (b2) were thermally fused.

(Comparative Example 2) In Example 2, (c2) and (
b2) and passed through hot air at 105°C, (c2
) and (b2) were adhered.

(Example 3) After forming a film by mixing calcium carbonate into polypropylene resin, the melting point excluding calcium carbonate was 160″C1, the maximum pore diameter was 2
μ, average pore diameter 0.6μ, Gurley method air permeability 120 seconds/1
00 cc, basis weight 63g10f, thickness 140μ microporous membrane (c3) (manufactured by Tokuyama Soda ■, NF sheet 5140
■) is mainly made of low density polyethylene with a melting point of 95°C.
1 400μ diameter granular resin (c3) (Asahi Kasei Kogyo ■
PAK 0025@) was sprayed at 10g10f,
Next, a film (b,) made mainly of polyamide resin with a melting point of 110°C, a thickness of 20μ, a pore diameter of O15rI1mφ, and a number of holes of 4/cT1 was layered and passed between a metal roll and a rubber roll heated to 100°C. Melting only the surface layer of c3), (a,) and (c3), (c3) and (bz)
was glued.

(Comparative Example 3) In Example 3, (a,) and (bz) were overlapped and 105
It was passed between a metal roll and a rubber roll heated to °C to bond (c3) and (bz) together.

The Gurley air permeability (sec/100 cc) of each packaging material obtained in the above Examples and Comparative Examples is summarized in a table and compared.

Note that the Gurley method air permeability was measured according to JIS L1096B.

(Example 4) With the (b) side of the air-permeable packaging materials obtained in Examples 1 to 3 facing inside, silica gel as a desiccant, activated carbon as a deodorizer, and iron powder as an oxygen absorber were placed in bags. Each of the shaped packaging materials was filled and sealed on three sides as shown in FIG.

Sealing conditions are 130°C using a heat seal bar.
for 1 second at 140° C. and 1 second at 140° C. under a pressure of 2.0 kg/cd.

(c,), (c2), and (c8) are each (b
, ), (b2), and (b,), and were heat-sealed without any gaps.

The breathable packaging according to the present invention (Example) has faster dehumidification,
It was useful for deodorizing and deoxidizing.

(Effect of the invention) In the present invention, microporous membrane or nonwoven fabric (a)
By using a packaging material with a structure in which a partially positioned hot-melt synthetic resin (c) is interposed between a permeable perforated synthetic resin film (b), this part (c) is Compared to conventional packaging materials that do not allow air permeability, air permeability can be further improved.

[Brief explanation of the drawing]

FIG. 1-1 is a cross-sectional view of a breathable packaging material constructed according to the present invention. 1-2 is a plan view of a breathable packaging material constructed according to the present invention. FIGS. 2 and 3 are cross-sectional views showing a breathable packaging made using a part or all of the breathable packaging material according to the present invention. FIG. 4-1 is a cross-sectional view of a breathable packaging material constructed according to a conventional method. FIG. 4-2 is a plan view of an air-permeable packaging material constructed according to a conventional method. a: Microporous membrane or non-woven fabric (a), b: Breathable perforated synthetic resin film having 1 hole (b), C: synthetic resin with a lower melting point than (b) (c), d: Other material film, 1: Hole part, 2: Heat seal part, □□-1"

Claims (5)

[Claims] (1) (a) The pore diameter is 50μ or less and the Gurley method air permeability is 0.
1 to 10,000 seconds/100cc between a microporous membrane or nonwoven material and a perforated synthetic resin film having a lower melting point than (b) and (a) and having air permeability, (c) , a synthetic resin with a lower melting point than that of (b) is partially placed, and (a) and (c), and (c) and (b) are bonded together to form a unitary structure of (a), (b), and (c). Breathable packaging material. (2) Using all or part of the breathable packaging material according to claim (1), with the (a) side as the outer surface and a solid contained therein;
A breathable envelope whose surroundings are heat-sealed to prevent the solid from leaking. (3) The microporous membrane or nonwoven fabric (a) according to claim (1) is made of a polyolefin resin film such as polyethylene or polypropylene blended with an inorganic material such as calcium carbonate or a fine filler. The breathable packaging material according to claim (1) and the packaging according to claim (2), which are a microporous membrane obtained by removal or a laminate of polyolefin fibers obtained by flash spinning. (4) the synthetic resin film (b) according to claim (1);
The synthetic resin (c) is polyethylene, ethylene-vinyl acetate copolymer resin, ethylene-acrylate copolymer resin, ethylene-methacrylic acid copolymer resin, ionomer resin, polyamide resin, modified resins thereof, or two of the above resins. The breathable packaging material according to claim (1) and claim (2), which are made of a material selected from the group consisting of a mixture of more than one species.
Encapsulation as described. (5) The synthetic resin (c) according to claim (1) is dotted,
or (a) located in a line or grid pattern parallel to the plane;
The breathable packaging material according to claim (1) and the packaging according to claim (2).