JPS6021239A - Cloth for packing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a packaging cloth suitable for shrink-wrapping items to be packaged.

In general, heat-shrinkable films made of polyvinyl chloride, long-chain branched polyethylene, etc. are often used for shrink packaging. However, these heat-shrinkable films have poor mechanical strength such as tear strength, tensile strength, and abrasion resistance, and are also prone to notch propagation. There were constant troubles such as breakage during storage or transportation. For this reason, the above-mentioned conventional heat-shrinkable films were hardly used in the field of heavy-duty packaging, and were mostly used in the field of light-duty packaging, where mechanical damage was relatively small.

Further, the heat-shrinkable film has a high temperature at which it can be shrink-packed, and therefore there is a problem in that the contents of the packaged items are limited.

Furthermore, the direction and amount of shrinkage are limited by the film forming machine, for example, very high shrinkage in the M direction and low shrinkage in the T direction, very high shrinkage in the M direction and very high shrinkage in the T direction, and conversely, low shrinkage in the M direction and very high shrinkage in the T direction. It is impossible to freely select the direction of shrinkage and the amount of shrinkage according to the shape and packaging form of the packaged item, and in fact, the shrinkage behavior changes only in a part of the entire width in the M direction and T direction. Things are completely out of reach. Therefore,
Although it is possible to shrink-wrap items with simple shapes,
Currently, if the shape of the packaged item becomes even slightly complicated, the desired shrink wrapping cannot be performed.

Furthermore, due to limitations in film-forming technology, the maximum width of the heat-shrinkable film that can be produced at the current technological level is 11,000 i to 1,500 mm, and for this reason as well, it has not been used in the heavy-duty packaging field. Ta.

The present inventors have arrived at the present invention as a result of intensive studies to solve the above-mentioned problems of heat-shrinkable films used in shrink packaging. This is a packaging cloth made by laminating woven or knitted fabrics in which one or both of the warp and the weft are made of thread-like or tape-like products made from the above products, with an intermediate layer interposed therebetween.

The heat-shrinkable thermoplastic resin filament or tape-like article of the present invention can be obtained, for example, as follows.

A linear polyethylene having short chain branches with a density of less than 0.945 g/- is extruded into a film, and after cooling, it is slit and stretched at 50 to 120°C and 4 to 9 times. Further, in order to improve stretchability and strength by blending polyethylene with a higher density into the linear polyethylene, the polyethylene is slit in the same manner as before and stretched at 70-120°C and 14-9 times. Furthermore, in order to improve the shrinkage stress retention rate at room temperature by blending a polypropylene homopolymer with the linear polyethylene, it is slit in the same manner as before and stretched at 70 to 120°C and 2 to 8 times.

It should be noted that outside of these stretching conditions, there is a concern that strength and heat shrinkage rate will decrease at low temperature and high temperature sides, strength and heat shrinkage rate will decrease at low magnification side, and stretching breakage will occur at high magnification side.

Furthermore, as the die slit used in carrying out the present invention, those conventionally generally used, such as a T-shaped die, circular die, filament-shaped nozzle, band-shaped rectangular nozzle, etc., can be used, and after extrusion molding, For cooling, for example, water cooling, air cooling, contact with a chill roll, etc. can be used. Furthermore, any stretching method such as oven stretching, roll stretching, wet stretching, or hot plate stretching may be used for stretching, but if there is a large difference between the melting point and the optimum stretching temperature, it is relatively inexpensive and requires heat control. It is preferable to use hot plate stretching, which is easy to carry out.

The thermoplastic resin used in the present invention includes an antioxidant, an ultraviolet deterioration inhibitor, a lubricant, a coloring agent, and the like.

may be blended.

According to the present invention, the heat-shrinkable and high-strength thread-like material or tape-like material obtained by the above method is applied to a part or all of the warp, a part or all of the weft, or a part or both of the warp and weft. The desired shrink wrapping cloth can be obtained by laminating the woven or knitted fabrics used for part or all of the parts with an intermediate layer interposed therebetween.

Weaving and knitting can be carried out using conventionally commonly used loom and knitting machine techniques. The weaving specifications are appropriately selected and determined depending on the shape of the article to be packaged. For example, if a shrinkable cloth that shrinks in the MD force direction (does not shrink in the TD force direction) is required, a heat-shrinkable thread or tape material as described above is used for the warp, and for the weft. It is sufficient to use a thread-like material or a tape-like material with a low heat shrinkage rate. Conversely, if a shrink cloth that shrinks in the TD force direction but not in the MD force direction is required, the warp and weft mentioned above may be used. It is sufficient to use a weaving specification that reverses the . Also, MD and TD
If a shrinkable cloth that shrinks in both directions is required, a thread-like material or a tape-like material having heat-shrinkable properties as described above may be used for both the warp and the weft. For example, when shrink-wrapping an unusually shaped object such as an automobile door, thread-like materials or tape-like materials with different heat shrinkage rates are used as warp threads according to the mold, and the weft threads have a certain heat shrinkage ratio. A thread-like material or tape-like material made of linear polyethylene having a certain ratio may be used. The heat shrinkage rate of the thread or tape can be adjusted by appropriately changing the density, melt flow rate, stretching temperature, stretching ratio, etc. of the linear polyethylene used, the composition using it, etc. I can do it.

In the present invention, two or more heat-shrinkable woven or knitted fabrics are used in the form of woven fabric/woven fabric, woven fabric/knitted fabric, or knitted fabric/knitted fabric, and the intermediate layer is sandwich laminated (hereinafter referred to as sandwich laminate). It is important to laminate them in a manner that

That is, the heat-shrinkable woven or knitted fabric alone is not sufficient to prevent damage due to vibrations during transportation, and may cause problems in heavy packaging, but by laminating two or more sheets using sand laminate. It can be greatly improved. In other words, the tensile strength is only about twice as high when two sheets are laminated, but the dynamic load impact resistance with respect to vibration damage is as follows: commercially available 150μ low density polyethylene film 1 film breaks 500 times, and laminated 2000 times.
This has been greatly improved, with no breakage after 15,000 times of sand lamination, and no damage even after 30,000 times of 3-sheet lamination, compared to 3,000 times for single-sided lamination. Note that it is important to use an intermediate layer with a relatively low melting point, and if woven or knitted fabrics are directly heat-sealed, they will shrink and the heat shrinkability during packaging will be greatly reduced.

The lamination method may be a normal method, and the intermediate layer is not particularly limited, but it is preferably one that has good adhesion to the woven fabric, such as a woven or knitted fabric made of the above-mentioned linear polyethylene or a blend composition based on this. The cloth is preferably the above-mentioned linear polyethylene or low-density polyethylene having long chain branches, and the woven or knitted cloth made of polypropylene is preferably polypropylene. Further, the adhesion may be improved by performing anchor treatment or the like.

The thickness of the intermediate layer is not particularly limited as long as the adhesiveness between the woven fabrics is good, but it is preferably 15 μm or more.

As described above, the present invention provides a packaging cloth that is capable of shrink-wrapping complex-shaped or large-sized items and is resistant to heavy packaging.

Hereinafter, the present invention will be explained in further detail by giving Reference Examples, Examples, and Comparative Examples.

Reference Examples 1 to 3 For the raw material resins shown in Table 1, a 65-g extruder and a 25-g extruder were used.
The original film was formed using an air-cooled inflation tube using a 0mm, g spiral die, and after slitting, it was stretched using a hot plate stretching machine at the temperature and magnification shown in Table 1 to form a 10mm thick film.
A tape of 00 denier was obtained. The tensile strength and heat shrinkage rate of these tapes were measured and the results are also shown in Table 1.

In Table 1, 1) It is a copolymer of ethylene and butene-1 and has short chain branching. 2) JIS K 6760 (Polyethylene) J
IS K6758 (Polypropylene) 3), J I
SL 1073 Chuck distance 300mm Pulling speed 300mm/mm 4) After immersion in a glycerin bath for 1 minute at each temperature Example 1~
4 Using the tapes in Reference Example 1.2.3 for the warp and weft respectively, a plain weave woven fabric was woven with 10 pieces x 10 pieces/inch using a 2700 width Sluzer loom, and the density was 0.919 g/
clls M F R0,8,! i' 710 mmO
Low-density polyethylene having long chain branches was laminated by sand-slumming to form an intermediate layer with a thickness of 25μ (Example 1.2).
．． 3). Furthermore, using the woven fabric and film on the same side as the cloth in Example 3, sandwich lamination was performed in the same manner to obtain a 5-layer packaging cloth. (Example 4) Various physical properties were measured for these packaging cloths, but the second
As shown in the table, the results were good.

Comparative Examples 1 to 5 Plain weave fabrics were woven and laminated on one side in the same manner as in Example 1.2.3, except that one side was laminated without sand lamination (Comparative Example 1.2.3).

For comparison, a commercially available 150μ thick shrink film made of low density polyethylene having long chain branches (Comparative Example 4) and a commercially available 110μ thick shrink film made of polyvinyl chloride (Comparative Example 5) were obtained.

Various physical properties were measured for these, as shown in Table 2.
As shown in Comparative Examples 1, 2, and 3, single-sided laminated sheets have poor dynamic load impact resistance, while shrink films made of low-density polyethylene with long chain branches as shown in Comparative Example 4 have poor tensile strength, tear strength, dart impact resistance, and impact resistance. The shrink film of polyvinyl chloride, as in Comparative Example 5, has low tensile strength, tear strength, dirt impact, and dynamic load impact resistance.

In table 2 1) After immersion in a glycerin bath for 1 minute at each temperature.

2) Dirt: 38%, fl hemisphere, 1m height.

3) The lowest temperature at which the car wheel disc can be wrapped with a 15% margin in length, heat-sealed at the edges, and tightly wrapped in a shrink tunnel in 20 seconds.

4) Minimum transit time that allows for tight packaging at 185°C in a shrink tunnel by heat sealing as in the previous section.

5) ◎ Very good, ○...Good, ×...Poor6)
Number of times when perforation was observed.

Patent applicant: Showa Denko Co., Ltd. Taisei Polymer Co., Ltd. Agent: Agent Sei Kikuchi

Claims (1)

[Claims] A packaging cloth made by laminating woven or knitted fabrics with heat-shrinkable thermoplastic resin threads or tapes in either or both of the warp and weft through an intermediate layer.