JPS608949B2 - Reinforced bag with breathability - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a strong bag with air permeability, and by improving the structure of the sheet that is the material of the bag, it is possible to easily manufacture a strong bag with air permeability. It was developed for the purpose of

BACKGROUND ART Conventionally, sheet-like base materials such as paper and random nonwoven fabrics have been reinforced with reinforcing materials and used for heavy-duty packaging bags and the like.

These are usually made by bonding stretched tape, thread, woven fabrics such as split fibers, and orthogonal nonwoven fabrics to paper or random nonwoven fabrics using adhesives. This can be done, for example, by applying an adhesive to one side of the base sheet and laminating a reinforcing material thereon, or by laminating the two together via a heat-melting film made of relatively low-melting-point plastic such as low-density polyethylene. It had been taken. However, in the case of using an adhesive, for example, if the adhesive is applied to the base sheet to ensure sufficient adhesion of the reinforcing material, the base sheet becomes clogged with the adhesive and loses its breathability. I end up. Furthermore, when laminated with a low density polyethylene film, air permeability is completely lost. Therefore, bags manufactured using these reinforced sheets are often used for applications that do not require breathability or, conversely, for applications that require water resistance.

On the other hand, bags for desiccant materials such as quicklime, which can be dangerous if they come in contact with the human body, need to have considerable strength and appropriate ventilation, and simple methods such as heat sealing are required. It is preferable that bags can be manufactured using The aforementioned reinforced sheet is also used for this type of application, but in this case it is suitable in terms of strength and heat sealability, but
There was an inconvenience that holes had to be drilled because there was no air permeability. In addition, for such applications, we use reinforcing materials that themselves have considerable porosity, such as woven or nonwoven fabrics for stretched tapes, and after applying adhesive to them, we bond them to a breathable base sheet. By doing this, a breathable reinforced sheet can be obtained, but when a bag is manufactured using this by heat sealing, the stretching effect of the reinforcing material is lost due to the heat during heat sealing, and the heat sealing part The strength will decrease. Furthermore, if hot melt adhesive is applied to both sides of the reinforcing material and a reinforcing sheet is used as a neck layer on the base sheet, it is possible to make bags by heat sealing, but in this case, the manufacturing cost is high and it is not economical. Not only is the performance inferior, but when heat-sealing the rice cake bag, there is a good chance that the parts without reinforcing material will be overlapped and heat-sealed, and if this is filled with powder, it will cause leakage. becomes. In this invention, when reinforcing a breathable base sheet with a reinforcing material 2 such as a non-woven fabric having a large number of closing holes 5 such as silk, a hot-melt adhesive layer is partially placed as described below. Made by laminating the two through 3,
A portion of the hot melt adhesive layer 3 is formed by openings 5 in the reinforcing nonwoven fabric.
This relates to a breathable reinforced bag characterized in that the reinforced sheet exposed from the entrance is used as the bag material, and the bag is made by heat sealing so that the exposed surface of the adhesive layer 3 is on the inside of the bag. Furthermore, the purpose is to obtain a reinforced bag with air permeability that is simple, inexpensive to manufacture, and which overcomes the drawbacks of the conventional method. As the breathable base sheet used in this invention, paper such as Japanese paper or ordinary Western paper, or random nonwoven fabric obtained by a spunbond method or a wet method is suitable. These have poor tear strength, and may not be able to be heat-sealed by themselves, or even if they can be heat-sealed, the sealing strength is low, but because the fibers are dense, powders,
This base sheet is suitable for the purpose of the present invention because it has excellent grain retention ability and is relatively inexpensive. The reinforcing material 2 used in this invention is a non-woven fabric with high tensile and tear strength, having a large number of openings in the form of a mesh or a lattice, and has a slight unevenness.
There are no particular limitations as long as it is suitable for use, but in particular, stretch-treated thermoplastic synthetic resin split fiber warp twill laminated nonwoven fabric (
Suitable materials include non-woven fabrics made of stretched thermoplastic synthetic resin tape (hereinafter referred to as "tape silk fabrics"), synthetic or natural organic fibers, grid-like non-woven fabrics made of glass fiber threads, etc. There is.

What we mean by split fabric here is a so-called split film made by making discontinuous cuts in a wide medium uniaxially stretched film (thickness of several tens of microns) made of high-density polyethylene, polypropylene, polyester, polyamide, polyvinyl alcohol, etc., using a slitter or splitter. Wep or slit wep (wep with a thickness of several tens of microns and fibers of several millimeters in length are connected in a network shape and have an endless continuous character in the length direction) is expanded several times, and this It is a mesh-like nonwoven fabric that is laminated using adhesive. Tape assembly is a method in which stretched tapes of several hundred to several thousand deniers made of high-density polyethylene, polypropylene, etc. are arranged in parallel on the zero plane at approximately equal intervals so as not to overlap each other. It is a grid-like nonwoven fabric made of layers of warp and weave using adhesive. In addition, lattice-like nonwoven fabrics made of synthetic or natural organic fibers or glass fiber threads are polyamide, polyester, polypropylene, high-density polyethylene, polyvinyl alcohol, cotton, rayon, glass fiber, etc. with tens to hundreds of deniers. This is a net-like nonwoven fabric in which the threads are arranged parallel to each other in a lattice pattern at intervals of several to several tens of ribs, layered in warp and warp layers, and fixed using an adhesive. Among the reinforcing materials 2 as described above, the tape in the middle of the split fabric 5, which is developed at a relatively high magnification of 0 (more than 2 times), is compared so that it has a gap of about 3 sides or more, as shown in the middle. A part of the hot melt adhesive layer 3 used for laminating the base sheet 1 and the reinforcing material 2, such as when using a coarsely arranged tape silk cloth or a grid-like nonwoven fabric of threads. When making bags by heat sealing using a reinforcing sheet in which a large proportion of the material is exposed through the holes in the reinforcing material 2, the exposed hot melt adhesive works effectively during bag making and has sufficient heat sealing strength. You get a bag.

However, the wari cloth developed at a relatively low magnification of 2 times or less,
When using a tape assembly in which the tape is relatively densely arranged with wide tapes on the 5th side or more and 3rd side or less, the exposed ratio of the hot melt adhesive is small;
Therefore, a bag having sufficient heat-sealing strength may not be obtained by using the hot melt adhesive layer 3 alone. In such a case, as described below, it is preferable to use a reinforcing material 2 which itself has thermal adhesive properties. In other words, for reinforcing cloth or silk tape, at least one side is made of a synthetic resin that has a relatively low melting point and is easily heat-sealable, such as low-density polyethylene or ethylene-vinyl acetate copolymer. A composite film made of a composite film having a layer is used, or a hot melt adhesive is applied to the split fabric or tape assembly using a roll coater, etc., and this is applied to the easily heat-sealable synthetic resin layer. Alternatively, the hot melt adhesive is laminated on the base layer so that it is present on the surface that is heat-sealed during bag making.

As a result, the easily heat-sealable synthetic resin film and hot melt adhesive are distributed over the entire surface of the reinforced sheet. The hot melt adhesive used in this invention is not particularly limited, and currently commercially available hot melt adhesives such as vinyl acetate and polyamide can be used. When the material 2 is made of thermoplastic synthetic resin, vinyl acetate is suitable because it has a relatively low melting point.

One method of laminating the breathable base sheet and the reinforcing material while maintaining air permeability by partially arranging the hot melt adhesive layer 3 is as follows:
There is a method in which hot-melt adhesive is applied in dots or lines using an embossed roll with irregularities spaced approximately 5 skins apart, and the reinforcing material is crimped onto this using a heated roll. According to this method, the hot melt adhesive has a strong tendency to penetrate into the base sheet, which not only impairs the air permeability of the base sheet, but also may not provide effective heat sealing strength.

The most common method is to use a hot melt adhesive wafer as the hot melt adhesive layer 3, which will be described below. As described in Japanese Patent Publication No. 51-9067, this hot-melt adhesive web is produced by arranging, for example, rayon-based materials in a cylindrical shape at intervals of several to several tens of ribs, and then running the web.
A cylindrical array yarn that runs around the outer periphery of a container in which the supplied hot melt melt is ejected from the outer periphery of the container into a large number of fibers by centrifugal force into a container that rotates at high speed and is installed at the center of the cylindrical array yarn. It is manufactured by attaching the threads horizontally at intervals of about 1 to 5 ribs, connecting the arrayed threads in the horizontal direction, flattening the whole, and taking it off. Thin threads of hot melt adhesive are arranged and fixed in the transverse direction at intervals of about 1 to 5 sides with respect to warp threads such as rayon threads. When carrying out the present invention, it is appropriate for the hot melt adhesive web to have a spacing of 5 to 3 ridges, but one with a relatively narrow spacing (1 to 2 strands) of twill threads (hot melt adhesive). It is preferable to use willow grade), and the reinforcing sheet for reinforcing of the present invention is manufactured by laminating the base sheet and the reinforcing material with these sheets in between and pressing them together with hot rolls. There are no particular limitations on the heat sealing method used in the present invention, and bar sealers, roll sealers, impulse sealers, etc. commonly used in this type of bag making may be used.

The heat-sealing temperature must be carefully controlled, especially when using reinforcing materials made of stretched thermoplastic synthetic resin; if the heat-sealing temperature is raised above its melting point, the stretching effect will be lost. Since the reinforcing effect of the heat-sealed part will be lost, if a reinforcing material whose melting point is lower than the melting point of the reinforcing material used, but higher than the melting point of the hot melt adhesive, and has thermal adhesive properties itself, the adhesion It is necessary to heat seal at a temperature above the melting point of the layer. The reinforced bag obtained by this invention can be used not only for quicklime but also for calcium chloride, desiccant such as silica gel, alumina gel, and molecular sieve, deodorizing agent such as carbon black, deoxidizing material such as sodium sulfite, and fumigation of grains, beans, etc. Suitable for packaging foods that will be stored later, fresh vegetables, fruits, etc.

Example 1 Using rayon paper (50 tar/re) as the base sheet 1, and warp/warp laminated nonwoven fabric made of split fibers of high density polyethylene ("Wa1"Fu" manufactured by Nippon Petrochemical Co., Ltd.) as the reinforcing material 2, A hot melt saddle weave (warp - Penberg thread, 5 skin pitch, striped thread - pinyl acetate hot melt adhesive, 2 rib pitch) is sandwiched between these, and the two are pressed together using a Teflon coated hot roll. A breathable reinforced paper was obtained.

This bag was made by heat sealing with a 120 qo bar sealer and was used as a desiccant bag containing quicklime. Example 0 A polypropylene spunpond nonwoven fabric (40 tare/pillow) was used as the base material sheet, and a tape fabric prepared as described below was used as the reinforcing material 2, and between these, Example 1 was used.
The same hot-melt adhesive web was sandwiched between them, and the two were pressed together using Teflon-coated hot rolls to obtain a breathable reinforced nonwoven fabric.

A bag obtained by heat-sealing this bag with quicklime inside with a bar sealer at 120° C. was a good desiccant bag with no leakage of quicklime powder. The tape assembly is made by stretching a composite film (thickness: 80 mm), which is made by laminating low-density polyethylene as the adhesive layer 3 on both sides of high-density polyethylene by co-extrusion method, to 9 times, and then slitting it in the 5th side. 1 inch (25.4 legs) of the stretched tape obtained by
Three pieces were aligned in parallel, laminated in the weft and warp, and then bonded under heat.

Example m Using kraft paper (78 tar/〆) as the base material sheet, and using 2.5 mm of polyester thread (15 mm) as the reinforcing material 2
A nonwoven fabric was arranged parallel to the warp and the warp at willow pitch and fixed in a lattice pattern with an adhesive, and the same hot melt adhesive web as in Example 1 was sandwiched between them.
The two were pressed together using a Teflon-coated hot roll to obtain breathable reinforced kraft paper.

A bag obtained by heat-sealing this bag with soybeans as its contents using a 12030 bar sealer could be directly subjected to ethylene oxide fumigation treatment.

[Brief explanation of the drawing]

FIG. 1 shows an example of a reinforcing sheet used in the present invention, and in this case, a grid-like nonwoven fabric of threads is illustrated as the reinforcing material. FIG. 2 is an enlarged conceptual sectional view of a heat-sealed portion of a bag manufactured by the method of the present invention using the reinforcing sheet shown in FIG. 1. 1: Motomura sheet, 2: Reinforcing material (in this case, a grid-like nonwoven fabric of yarn is exemplified), 3: Hot melt adhesive layer (in this case, a hot melt adhesive web is exemplified), 4: Hot melt adhesive web Thread used, 5:
Seki Kong. Brush drawing 2nd drawing

Claims (1)

[Scope of Claims] 1. A hot melt adhesive layer is partially disposed between a breathable base sheet and a reinforcing material having a large number of mesh-like openings, and the reinforcing material is attached to the base sheet. A reinforcing sheet with a portion of the hot-melt adhesive exposed through the apertures of the reinforcing material is overlapped so that the exposed surfaces of the hot-melt adhesive are on the inside of each other. A reinforced bag characterized by being formed by heat-sealing a reinforced sheet. 2. The reinforced bag according to claim 1, characterized in that the reinforcing material is a warp/warp laminated nonwoven fabric made of split fibers of stretched thermoplastic synthetic resin or a warp/warp laminated nonwoven fabric of stretched thermoplastic synthetic resin tape. 3. The reinforced bag according to claim 1, characterized in that the reinforcing material is a lattice-like nonwoven fabric of synthetic or natural organic fibers or glass fibers. 4. The reinforced bag according to claim 1, characterized in that the reinforcing material is a nonwoven fabric that itself has thermal adhesive properties. 5 In claim 1, the hot melt adhesive layer is made of a large number of hot melt adhesive threads that are attached to a large number of threads that are arranged parallel to each other on a plane at substantially the same intervals, and substantially perpendicular to the threads. A reinforced bag characterized by: