JPH04229253A - Air-permeable packing material - Google Patents

Abstract

PURPOSE:To obtain a packing material whose air-permeability is within a specific range, by a method wherein a nonwoven sheet having a hole diameter within a specific range and paper having the air-permeability are stuck to each other. CONSTITUTION:A nonwoven sheet is obtained by performing self-fusion partly among fibers of a laminated body of a three-dimensional netted fiber obtained from a polymer composed mainly of polyolefin resin by a slush.spinning methods with a heated roll having a temperature close to the melting point of raw materials of a resin material. The obtained nonwoven sheet possesses a fine hole, the diameter of the hole is 0.01-500mum, preferably 0.05-50mum, Gurley air permeability is 0.1-10000sec./cc, preferably 1-5000sec./100cc and the sheet does not permeate water at the normal temperature. A method of sticking the nonwoven sheet to paper having air permeability is performed by an adhesive agent and/or heat fusing. The air-permeability of 0.1-10000sec./cc is necessary so as not to take out an inside filler, obtaining of gas permeability and not to admit water within.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breathable packaging material that has excellent water resistance, air permeability, and heat resistance, and thus can be easily filled at high speed.

0002

BACKGROUND OF THE INVENTION In recent years, requirements for packaging materials have become increasingly complex. In particular, when it comes to food packaging, consumer preferences are changing to "fresher products."
Since then, many long-term freshness-preserving agents have been introduced to the market with the intention of producers to expand the market.

[0003] For example, there are methods that utilize a desiccant, an oxygen scavenger, an ethylene gas adsorbent, a carbon dioxide regulator, a cold storage agent, a heat insulating agent, and the like. Particularly in the case of humid foods, moisture in the food may migrate to the packaging material for the drug, causing oozing and other deterioration in appearance quality.

[0004] Therefore, microporous membranes having fine pores with excellent water resistance and air permeability have been attracting attention. However, since these materials are made from single-component synthetic resins such as polyethylene and polypropylene, they have problems such as difficulty in being processed by high-speed filling and packaging machines.

[0005] As a countermeasure to this problem,
It is proposed in the above publication that a packaging material made by laminating a microporous membrane and a perforated film with a low softening point is used as an oxygen scavenger packaging material.

However, in this case, since the raw material is synthetic resin, it has low heat resistance, and when filling and packaging is stopped,
Problems such as melting and cutting occur. In addition, the chemical generates heat and melts, creating holes.

[0007]

[Problems to be Solved by the Invention] The present inventors took advantage of the characteristics of microporous membranes, which are excellent in water resistance and air permeability, and studied the problem of melting of microporous membranes, and arrived at the present invention.

[0008]

[Means for Solving the Problems] That is, the present invention consists of bonding a non-woven sheet with a pore size of 0.01 to 500 μm to a paper having air permeability using an adhesive and/or heat fusion, and It is made of an air-permeable packaging material with a degree of 0.1 to 10,000 seconds/100cc.

The present invention will be explained in more detail below. In the present invention, paper is not particularly limited as long as it has air permeability. Western paper, high-quality paper, Japanese paper, and synthetic paper mixed with natural fibers, synthetic fibers, etc. are used. In particular, high-quality paper with high whiteness is preferred.

[0010] In the present invention, a nonwoven sheet refers to a polymer mainly composed of polyolefin resin such as polyethylene, polypropylene, ethylene copolymer, propylene copolymer, etc., which is oriented and forms three-dimensional network fibers. It is usually obtained by flash spinning method (for example, Japanese Patent Application No. 62-295978, Japanese Patent Application No. 63-
No. 28933).

[0011] A laminate of three-dimensional network fibers is obtained by partially self-fusing the fibers using a hot roll at a temperature near the melting point of the resin material raw material. The obtained nonwoven sheet has micropores with a pore diameter of 0.01 to 500μ, preferably 0.0μ.
5 to 50μ, and Gurley air permeability is 0.1 to 1
0,000 seconds/100cc, preferably 1-5000
sec/100cc, does not allow water to pass through at room temperature, and has a water pressure resistance of 500 to 3000 mmH2O.

If the pore size of the nonwoven sheet is smaller than 0.01μ, the air permeability will be poor, and if it is larger than 500μ,
It has poor water resistance, and there is a risk of leakage, especially of powder and liquid. The basis weight of the nonwoven sheet can be freely selected depending on the purpose, but 30 to 100 g/m2 is preferably used.

In the case of high-speed filling and packaging, the above-mentioned non-woven sheet may be used, but for the purpose of improving processability such as sealing strength, a non-woven fabric with a low softening point, a perforated film, a microporous film, etc. are laminated together. Alternatively, 2 to 20 g/m 2 of heat-sealable resin may be applied using a gravure roll or the like.

[0014] In the present invention, the paper and nonwoven sheet are bonded together using an adhesive and/or heat fusion. What is required at this time is that there are no partial defects such as wrinkles. As the adhesive, commonly used adhesives such as ethylene-vinyl acetate copolymer resin, acrylic acid ester resin, ionomer resin, thermoplastic elastomer, etc. are used.

However, if the entire surface is coated, air permeability will be lost, so partial coating using a gravure roll or the like is preferable. In addition, the amount of adhesion should be determined by considering the desired air permeability and adhesive strength.
It can be preferably carried out at ~20 g/m2.

Furthermore, as a method for bonding paper and a nonwoven sheet, it is possible to bring them into contact with a heated thermal roll or the like to partially melt and thermally bond them. At this time, adhesion can preferably be achieved by laminating or applying a heat sealing agent with a low softening point to at least one of the surfaces of the paper or nonwoven sheets to be bonded.

[0017] The air permeability of the breathable packaging material of the present invention is 0.1.
~10,000 seconds/100cc means a desiccant,
Oxygen absorber, ethylene gas adsorbent, CO2 gas regulator,
Necessary for the purposes of the present invention, such as preventing the internal filling material from leaking out, ensuring gas permeability, and preventing water from entering the packaging material when used for packaging cold storage agents, heat insulators, etc. It is.

If the air permeability is less than 0.1 sec/100 cc, there is a risk that the powder inside the packaging material may leak or liquid may seep out. Moreover, if it is 10,000 seconds/100 cc or more, the air permeability is poor and the intended function of the present invention cannot be exhibited, which is not suitable.

[0019] The present invention will be explained in detail below using Examples, but these do not limit the scope of the present invention. In addition,
The definitions and measurement methods of the properties described in the Examples are as follows.

■ Air permeability; JIS-L-1096
Measure according to Method B. ■ Seal strength; sample width 15
A piece of mm x 15 cm is taken and 180 degree peeling is measured using Tensilon.

[0021]

[Example 1] High quality paper (basis weight 40g/m2, air permeability 15
sec/100cc) and a nonwoven sheet of three-dimensional reticulated polyethylene fiber obtained by flash spinning method [fabric weight 60g/m2, average pore diameter 3μ, air permeability 20sec/10
0cc, Luxar H (trade name) manufactured by Asahi Kasei Industries, Ltd.] were bonded together using an adhesive.

[0022] An adhesive [Chemipearl resin (S-100) manufactured by Mitsui Petrochemical Industries, Ltd.] was applied using a gravure roll, and was passed between a heating roll and a rubber roll for adhesion. The obtained sheet had an air permeability of 45 seconds/100cc.

[0023] Next, the obtained packaging material was made into bags. The quicklime desiccant was made into a bag at a temperature of 175° C. using a three-sided seal type high-speed filling packaging machine, with the nonwoven sheet of the heat-sealing layer placed on the inside. No transparency phenomenon on the seal surface, seal strength 850g
/15mm was obtained. Even when stopped midway, no problems such as cutting due to melting occurred.

[0024]

[Example 2] A heat sealing agent [manufactured by Mitsui Petrochemical Industries, Ltd.] was applied to the surface layer of a nonwoven sheet of three-dimensional reticulated polyethylene fiber (fabric weight 40 g/m2, air permeability 15 seconds/100 cc).
Adhesive amount of Chemipearl resin (S-100) 8g/m2
Coated with Japanese paper (basis weight 60g/m2, air permeability 0.2 seconds/
100 cc) was passed between a heating roll and a rubber roll at a temperature of 140°C, and thermally fused and bonded by heat-pressure processing.

The air permeability of the obtained sheet was 115 seconds/10
It was 0cc. Next, the obtained packaging material was made into bags. The nonwoven sheet of the heat-sealing layer was placed on the inside, and an ethylene gas adsorbent was added using a heat-roll four-side sealing high-speed filling packaging machine to form a bag. A seal strength of 770 g/15 mm was obtained, and even when stopped midway, no problems such as cutting due to melting occurred.

[0026]

[Example 3] A two-component spunbond nonwoven sheet with a polyethylene sheath and a polyester core (fabric weight 20 g/m2, transparent Temperature 0.1 seconds/
100cc) on one side, low density polyethylene powder 5g/
m2 was evenly distributed and laminated together, and then laminated on the other side in the same manner as in Example 1.

The air permeability of the obtained sheet was 40 seconds/100
It was cc. Next, the obtained packaging material was made into bags. The nonwoven sheet of the heat-seal layer was placed on the inside, and an oxygen absorber was added using a four-side sealing high-speed filling packaging machine to form a bag. A seal strength of 1150 g/15 mm was obtained, and the seal surface did not become transparent, and bags could be made. Although moist rice cake was placed in the bag-made product, there were no problems such as the oxygen absorber seeping out.

[0028]

[Comparative Example 1] High-quality paper (basis weight 40g/m2, air permeability 15
sec/100cc) and a 25μ polyethylene film were laminated in the same manner as in Example 1 to obtain a sheet. The sheet had an air permeability of 20,000 seconds/100 cc or more, had no air permeability, had low mechanical properties, and could not be the object of the present invention. The results are summarized in the table below.

[0029]

[0030]

[Effects of the Invention] The breathable packaging material of the present invention is made by bonding paper and a microporous nonwoven sheet, and has excellent water resistance and transparency as well as toughness that makes it difficult to tear. Furthermore, since there is paper that does not melt when heat-sealing, even if it is packaged using a high-speed filling machine, there will be no problems such as cutting due to heat-sealing or fusing it to heat-sealing rolls, bars, etc., making it easier to make bags. Can be performed well. Therefore, it can be preferably used for packaging materials such as desiccants, oxygen scavengers, ethylene gas adsorbents, CO2 gas regulators, cold storage agents, and heat insulating agents.

Claims (1)

[Claims] Claim 1: A nonwoven sheet with a pore size of 0.01 to 500 μm and a paper having air permeability are bonded together by adhesive and/or heat fusion, and the Gurley air permeability is 0.1 to 10,000 seconds. /100cc. A breathable packaging material.