JPS6059860B2 - Composite tough sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strong composite sheet used for heavy duty packaging bags, etc. More specifically, the present invention relates to a strong composite sheet used for heavy duty packaging bags, etc. Flat yarns made by slitting a thermoplastic resin film are arranged in parallel at regular intervals in a direction perpendicular to the stretching direction with the transversely stretched film without using an adhesive medium, and the flat yarns themselves The ratio of the area occupied by the flat yarn to the area of the gap between the flat yarns is 30 to 70.
0 to 30, and further relates to a composite sheet in which a sheet-like material is laminated over the entire upper surface via an adhesive medium.

Conventionally, composite sheets have been commercially available as base materials for heavy-duty packaging, made by bonding woven cloth made of thermoplastic resin yarn stretched in the longitudinal direction and kraft paper with thermoplastic resin, such as low-density polyethylene. It has been widely used as a substitute for multilayer kraft bag paper due to its moisture-proof properties.

However, despite the high-speed processing in the bonding process, the production rate in the knitting process is low, resulting in increased production costs.
This has the disadvantage of inevitably increasing costs. This drawback is that the knitting process of the thermoplastic resin yarn stretched in the longitudinal direction is omitted, and the thermoplastic resin flat yarn stretched in the longitudinal direction is mainly placed on the thermoplastic resin film stretched in the transverse direction. The stretched flat yarns are arranged parallel to each other at regular intervals so that the stretching directions are perpendicular to each other without intervening an adhesive medium, and then a sheet-like J article is laminated on top of the stretched yarns with an adhesive medium interposed over the entire surface. I filed an application earlier stating that this could be resolved. (Unexamined Japanese Patent Publication No. 10883/1983). Composite sheets with this type of structure can not only be produced at low cost because the manufacturing process is limited to just the adhesion process, but also maintain a balance of strength in the vertical and horizontal directions, as well as maintain a textile-like texture. It is a strong sheet and has properties useful for various protective sheets, heat-sealed or glued heavy-duty packaging, etc. but,
When this composite sheet is used as a machine-sewn heavy bag, the sewing machine needle hole and the longitudinally stretched yarn align, and the stress applied to the sewing machine needle hole may propagate in the lateral direction during a drop strength test, causing yarn breakage. Depending on the application, it may be necessary to reinforce the sewing machine seams with kraft paper.
As a result of intensive studies to further eliminate the above-mentioned drawbacks, the inventors of the present invention have made independent longitudinal cuts in the longitudinally stretched flat yarn and laminated it with a sheet-like material without expanding the yarn, thereby reducing the stress caused by sewing threads. We have discovered that it is possible to dramatically increase the strength of heavy packaging by preventing lateral propagation and improving the strength of the perforated seams. In the present invention, a thermoplastic resin film mainly stretched in the transverse direction refers to a thermoplastic resin film stretched in a direction perpendicular to the length direction of the film, and the thermoplastic resin is crystalline polypropylene, high-density polyethylene, or polyethylene terephthalate. is suitable.

Stretching may be done by blow method, tenter method, or any other existing stretching method, and the stretching ratio is 2 to 2.
b times is applicable.

The thickness of the stretched film can be appropriately selected depending on the purpose, but a thickness in the range of 10 to 100 microns is preferred.

The sheet material of the present invention may be paper such as kraft paper or stretchable kraft paper (eg, Kurupakku paper (trade name, manufactured by Sanyo Kokusaku Valve Co., Ltd.)), as well as sheets of cloth, metal foil, and the like.

The basis weight is 50 to ζ150g/i for paper, 4 for cloth
The suitable thickness of the metal foil is 0 to 150y/i, and the thickness of the metal foil is 12 to 30μ. The machine-stretched thermoplastic flat yarn of the present invention is produced by slitting a machine-stretched film of crystalline polypropylene, high-density polyethylene, or polyethylene terephthalate.

Blow method and other stretching methods can be used for longitudinal stretching, the stretching ratio is 2 to 10 times, and the film thickness after stretching is 1
0 to 100μ is preferable. The film slit width is 3
~10! ! The spacing between a1 yarns is 43~8wA
A range of is suitable. As the adhesive medium, any material can be used as long as it can bond a transversely stretched thermoplastic resin film, a longitudinally stretched thermoplastic resin flat yarn, and a sheet-like body, such as low-density polyethylene, high-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer,
Examples include various hot melt adhesives and various pressure sensitive adhesives.

The adhesive medium is preferably used in a molten state or as a solvent solution, and the coating amount is preferably 5 to 100 f/Rrt. The longitudinally oriented thermoplastic resin flat yarn having independent cuts of the present invention is produced by forming independent longitudinal cuts in a staggered manner using an open fiber roll provided with a file or multiple knife blades in a longitudinally oriented film. It refers to a product in which a longitudinally stretched film is slit into a flat yarn, and then independent vertical cuts are made in a staggered pattern using a spreading roll. At least three independent cuts must be present at appropriate intervals in the width direction of the slit yarn, and their length should be 3 to 15 m, preferably 6 to 11 Tfa, with no deviation in the length direction. They exist in a staggered manner. In strings, staggered refers to a state in which the slit yarn is staggered in the length direction so that there are as few as three vertical cuts in each yarn in a direction perpendicular to the length direction. The lengthwise distance between adjacent cuts is 1
~3T! The appropriate interval in the GRl width direction is 1 to 4 squares.
Even if the sewing machine needle hole and the longitudinally stretched yarn are aligned with each other by this cut, the stress caused by the sewing thread can be prevented from being propagated in the lateral direction, thereby preventing the yarn from breaking.
As a result, the strength of the heavy package can be significantly improved.

Since the above objective can be achieved without widening the cuts, the composite sheet can maintain a balance of strength in the vertical and horizontal directions and also maintain a woven-like texture. The content of the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view for explaining the structure of the composite tough sheet according to the present invention, in which 1 is a sheet-like material such as paper, 2 is an adhesive medium, and 3 is a longitudinal direction with independent cuts. Stretched thermoplastic resin flat yarn 4 indicates a transversely stretched thermoplastic resin film, and its characteristics are as follows: The sheet-like body 1 is formed from the entire one side of the longitudinally stretched thermoplastic resin flat yarn 3 through an adhesive medium 2. A portion obtained by subtracting the area occupied by the flat yarns 3, that is, a gap portion of the horizontally stretched film 4 created between the parallel flat yarns 3 is bonded via the adhesive medium 2. The area occupied by the independently scored longitudinally oriented thermoplastic flat yarns 3 and the juxtaposed flat yarns 3
The ratio of the area of the gap between the comrades is 30 to 7
A ratio of 0:70 to 30 is suitable; if the gap is too large, the adhesion between the sheet-like material 1 and the longitudinally stretched flat yarn 3 will be poor; Although the adhesion with the flat yarn is improved, the adhesion between the sheet-like material 1 and the horizontally stretched film is deteriorated, so the above-mentioned limitations were made. FIG. 2 is a plan view for explaining the structure of a longitudinally stretched thermoplastic resin flat yarn having independent cuts.

In the figure, numeral 3 denotes a longitudinally stretched thermoplastic resin flat yarn, and 6 denotes independent cuts, which are made in a staggered manner so that at least three of them exist in the width direction of the yarn. FIG. 3 shows an example of the method for manufacturing the composite sheet of the present invention.

Adhesive medium 2 is extruded onto the surface of sheet-like material 1 from T-die 10.
A guide roll 1 having a comb-shaped spacing holder is used to simultaneously extrude the sheet material from the opposite direction to the T-die.
After being arranged in parallel at a predetermined interval according to step 1, the longitudinally stretched flat yarns 3 with independent cuts made by a spreading roll 9 rotating at high speed between pinch rolls 7 and 8 are bonded onto the horizontally stretched film 4. Connect without using a medium,
The composite sheet 5 is obtained by pressure bonding using a breath roll 12 and a chill roll 13. Figure 3 shows a case in which a longitudinally stretched film is slit into flat yarns and then independent cuts are made. Of course, it is also possible to do so. When hot melt resin or pressure sensitive adhesive is used, a curtain flow coater or a roll coater can be used in place of the extrusion T-die 10 shown in FIG. According to the present invention, a composite sheet-like product that has a texture similar to cloth and has significantly stronger sewing seam strength without using knitted cloth can be produced using a band-like material such as flat yarn, resin film, paper, etc. Highly efficient production can be achieved through one-step work.

Next, further explanation will be given with reference to examples.

Example: A 25μ thick, 5m wide, 6-slit cut length 6 on a 20μ thick high-density polyethylene film stretched mainly in the transverse direction.
T1rJR, longitudinally stretched high-density polyethylene flat yarn having independent cuts with an interval of 2 m in the longitudinal direction of adjacent cuts and 1 m in the width direction is fed out in parallel at approximately 5 thread intervals. Stretchable kraft paper and temperature 290
Simultaneous adhesion was achieved using low density polyethylene extruded at °C as an adhesive medium.

The low density polyethylene layer as an adhesive medium had a thickness of 25 μm. There is also a composite sheet with exactly the same structure as above but without cuts in the flat yarn (Comparative Example 1), and a conventional 1
Knitted cloth made of axially stretched high-density polyethylene yarn
A composite sheet (Comparative Example 2) was prepared by adhering 0y/y stretchable kraft paper with low density polyethylene.

The knitting cloth used had 4 950 denier yarns per inch as the warp and 3.5 950 denier yarns per inch as the weft. Such as 3
Tensile strength, tear strength and perforation seam strength tests were conducted on the seed sheets, and the results are shown in Table 1.

In the examples, tensile strength, tear strength, and machine seam strength were each measured using a Tensilon tensile tester (manufactured by Toyo Baldwin Co., Ltd.) in accordance with JISP-8113sJISL-1079 and JISZ-10215, and tested five times. It is shown as the average value.

As is clear from Table 1, the tensile strength of the flat yarn with cuts made according to the present invention is slightly lower than that without cuts, but the tear strength is improved.
In particular, a remarkable improvement was seen in the strength of the sewing machine seams.

It was also found that the machine seam strength was superior compared to composite sheets using conventional yarn fabrics. Next, bags were made using the above test and their strength was compared by a drop test.

The bag size was 665T1n x 48072, the body was hot-melt glued, the top and bottom were machine sewn, polyethylene pellet resin 25k9 was sealed inside, and horizontal, vertical, and inverted drop tests were conducted. Machine stitch with a needle hole pitch of 9T!
It was set as n. The test results are shown in Table 2. The drop test was conducted as follows.

In the horizontal drop test with polyethylene pellet resin 25k9 sealed, the bag filled with polyethylene pellet resin 25k9 was held in a horizontal state at a height of 1.5 Tr1 and dropped, and this operation was repeated until the bag broke. was defined as the number of falls.

A broken bag was determined when 59 or more contents were spilled. In the vertical drop test, the bag was held vertically at a height of 0.67 yL and dropped vertically, and the number of drops until the bag broke was counted. In the inverted drop test, the bag was placed on a belt conveyor operating at an inclination angle of 35 and a moving speed of 6 m/min, and the bag was placed at a height of 1.5 m. It was rotated once and dropped from the position. Count the number of times until the bag breaks by dropping it repeatedly! Ta. Is each item 2 on the test? The average number of drops was taken as the numerical value for each drop test. As shown in Table 2, when the composite sheet with cuts according to the present invention is compared with the composite sheet without cuts, a marked improvement is seen in each drop test.
It is clear that he is highly suited as a.

Even when compared with the case where yarn fabric is used, the strength tends to be the same or slightly improved, and it is clear that the method according to the present invention is in a significantly advantageous position over the conventional method when manufacturing costs are taken into account.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view showing the structure of the composite tough sheet according to the present invention, FIG. 2 is a plan view of the longitudinally drawn yarn with independent cuts according to the present invention, and FIG. 3 is a diagram showing the manufacturing of the composite tough sheet according to the present invention. An example of a process diagram is shown. In the figure, 1: sheet-like material, 2: adhesive medium, 3: longitudinally stretched thermoplastic resin flat yarn with independent cuts, 4: transversely stretched thermoplastic resin film, 5: composite tough sheet, 6
: Independent cut, 7: Pinch roll, 8: Pinch roll, 9: Spreading roll, 10: Extrusion T die, 11: Guide roll, 12: Press roll, 13: Chill roll, 1
4: non-bonded part, 15: longitudinally stretched thermoplastic resin flat yarn.

Claims (1)

[Claims] 1. A thermoplastic resin film stretched in the longitudinal direction is slitted onto a thermoplastic resin film stretched mainly in the transverse direction, and a flat yarn is slit in a direction perpendicular to the stretching direction of the transversely stretched film. The flat yarns are arranged at regular intervals without an intervening adhesive medium, and the ratio of the area occupied by the flat yarns themselves to the area of the gap between the flat yarns is 30 to 30.
70:70 to 30, and furthermore, independent longitudinal cuts are provided in the longitudinally stretched flat yarns of the composite sheet on which the sheet material is laminated on the entire upper surface via an adhesive medium. Features: Composite strong sheet. 2. The composite tough sheet according to claim 1, wherein the longitudinally stretched flat yarns have 3 to 6 independent longitudinal cuts.