JP2005088893A - Bag having mouth whose shape can be maintained - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bag, which has a mouth that can be deformed at any part into any angles, where a deformed state can be retained until another deformation into a different angle, so that the mouth can be deformed any times freely. <P>SOLUTION: According to the plastic bag, a shape-retaining tape, which is made of a plastic, preferably of a polyolefin, is welded or glued along the mouth of the bag, preferably at the outside of the mouth. The shape-retaining tape is a plastic tape that is rolled and drawn longitudinally to be 10 to 40 times longer than the original state. When any part of the tape is bent, the part bends at any angle easily and retains the bent angle until a force to deform the part into a different bend angle is applied to the part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a bag in which the shape of the bag mouth can be freely deformed, and more specifically, the bag mouth can be closed, fully opened, or provided with a beak-shaped spout, and various shapes can be deformed, and the shape can be lengthened. The present invention relates to a bag that can be held and can be kept constant in the shape of a bag mouth that can be newly deformed into another shape.

  Recently, plastic bags are widely used in every field of life because they have many advantages such as transparency, flexibility, sealing, printability, and processability. Examples of the shape of the bag include a two-side seal bag, a three-side seal bag, a pillow bag, a gusset bag, and a stand bag. In addition to single-layer films made of one type of plastic, the film used to make the bags is also a laminate of different plastic films, or a laminate of materials other than plastic, such as paper and aluminum layers. Film is widely used.

  Conventionally, a plastic film used for a bag is thin and can be changed into various shapes, but the shape cannot be maintained. Even if the bag mouth is spread out in a circle and the bag is raised, if you release your hand, the bag will fall and the bag mouth will turn sideways. On the other hand, the wire can be bent into various shapes from an arbitrary part, and it is conceivable to pass the wire through the bag mouth. However, when it is discarded, the wire is made of metal and becomes incombustible waste, which is not preferable for protecting the global environment. Plastics can burn, especially polyolefins do not generate toxic gases when burned.

  For example, in a process of bagging a product or the like, if the bag mouth is fully open in a circular shape, the operation is quick. Even if it is a garbage bag etc., if the bag mouth is fully open, it can be thrown in and it is convenient, and a non-metal material, preferably a plastic material, which can close the bag mouth when not in use, is preferably bonded or fused to the bag mouth. A plastic bag was sought.

  An object of the present invention is to solve the above-mentioned problems, and its configuration is such that a shape-retaining tape made of plastic, preferably polyolefin, is fused or bonded along the bag mouth of the plastic bag, preferably outside the bag mouth. The shape-retaining tape is a plastic tape stretched in the length direction at a total stretch ratio of 10 to 40 times, and is easily bent to an arbitrary angle when an arbitrary portion is bent, and then different The previous bending angle can be maintained until a correction force is applied to the bending angle.

  That is, the present invention is made of plastic, particularly polyolefin, and can be bent at an arbitrary angle at an arbitrary position such as a wire or a thin metal plate. This bending angle can be maintained as it is and bent at another angle. If desired, the material can be bent freely and the angle can be maintained, and a material that can be repeated any number of times is fixed to the bag mouth of the plastic bag.

  By fusing or adhering the shape retention tape to the bag mouth, any part of the bag mouth can be deformed at any angle, and the deformed state can be held indefinitely, and then it is desired to be deformed to another angle. The case can be freely deformed as many times as possible, and the function of the bag has been dramatically improved.

  The plastic bag of the present invention is not particularly limited. The size can be as small as 3 cm on a side to as large as 1 m or more on a side. Two-side seal bags, three-side seal bags, pillow bags, gusset bags, stand bags, etc. can be used, and the ratio of length and width can be freely set.

  As the material, polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, polystyrene, polyester, polyamide and the like can be used, and these are used in a single layer or laminated. Or different materials, such as an aluminum vapor deposition layer, aluminum foil, paper, and a fiber, can also be laminated. Also, different plastic layers such as poval, polyvinylidene chloride, and eval can be laminated.

  The plastic shape-retaining tape used in the present invention is preferably a stretched product of a polyolefin resin sheet such as polyethylene or polypropylene. The total draw ratio of this polyolefin is 10 to 40 times, preferably 15 to 35 times, because if it is small, shape retention may be insufficient, and if it is large, it may be liable to tear laterally.

  As the olefin resin constituting the polyolefin resin sheet, any polyolefin resin having film forming ability can be used, for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, ethylene. -Propylene copolymer, ethylene-pentene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-propylene-butene copolymer For example, high-density polyethylene is preferably used.

If the density of the high-density polyethylene is reduced, the shape retention is not improved even if it is stretched, so 0.94 g / cm ³ or more is preferable.
The weight average molecular weight of the high-density polyethylene is preferably 200,000 to 500,000, because shape retention is not so improved even if it is stretched too much, and film formation and stretching becomes difficult if it is too large. The melt index (MI) is preferably from 0.1 to 20 and more preferably from 0.2 to 10 because the film formability is excellent.

  In the present invention, the high-density polyethylene may be used alone, but other polyolefins may be mixed in a proportion of 30 parts by weight or less with respect to 100 parts by weight of the high-density polyethylene. Examples of other polyolefins to be mixed include low density polyethylene, ethylene-vinyl acetate copolymer, and polyvinyl acetate. Further, the high-density polyethylene may be cross-linked.

As the stretching method of the polyolefin resin sheet in the present invention, any conventionally known method is adopted, but since the total stretching ratio is 10 to 40 times and the film is highly stretched, the olefin resin sheet is rolled and then stretched. Or the method of carrying out the multistage extending | stretching which repeats extending | stretching in multiple times is preferable.
The rolling is a method in which a polyolefin-based resin sheet is supplied to a pair of rolls rotating in opposite directions, rolled to reduce the thickness of the sheet, and stretched. Since the resin is dense without being oriented, it is highly stretchable.

When the rolling temperature is lowered, it cannot be uniformly rolled and melted and cut when it is higher. Therefore, the roll temperature during rolling is preferably in the range of "melting point-40 ° C" to the melting point of the polyolefin resin of the polyolefin resin sheet to be rolled, More preferably, it is “melting point−30 ° C.” to “melting point−5 ° C.” of the polyolefin resin.
In the present invention, the melting point refers to the maximum point of the endothermic peak that accompanies melting of crystals, which is recognized when thermal analysis is performed with a differential scanning calorimeter (DSC).
Further, if the rolling ratio is small, the subsequent stretching is burdened, and increasing the rolling ratio makes rolling difficult, so 4 to 10 times is preferable. In the present invention, the rolling ratio and the stretching ratio are values obtained by dividing the cross-sectional area of the sheet before rolling or stretching by the cross-sectional area of the sheet after rolling or stretching.

Stretching may be any conventionally known method, and examples thereof include a method of stretching while heating with a heater or hot air by a roll stretching method or a zone stretching method.
When the stretching temperature is lowered, the sheet cannot be uniformly stretched, and when it is increased, the sheet is melt-cut. Therefore, the range of “fusion-60 ° C.” to the melting point of the polyolefin resin to be stretched is preferable. "-" Melting point-5 ° C "is more preferable.
Further, the draw ratio after rolling may be determined from the total draw ratio in consideration of the roll ratio, but if the drawing after rolling is small, not only the mechanical strength is not improved but also the necessary shape retention cannot be obtained. Therefore, 1.2 times or more is preferable, More preferably, it is 1.5 times or more. The total draw ratio is a value obtained by multiplying the rolling ratio and the drawing ratio after rolling.

The shape-retaining tape of the present invention is not particularly limited as long as it is a tape mainly composed of a polyolefin-based resin. For example, a plurality of the above-mentioned polyolefin-based resin sheets may be laminated by adhesion or heat fusion. Good.
As the shape-retaining tape of the present invention, a tape obtained by cutting the above sheet into a necessary width in the stretching direction can be used. Such sheets are commercially available, and for example, forte (trade name, manufactured by Sekisui Chemical Co., Ltd., polyethylene stretched sheet) can be purchased. This sheet can be cut to the required width in the stretching direction to obtain the shape-retaining tape of the present invention.

In fixing the shape holding tape to the bag mouth, it can be fused with the film on the outer surface of the bag material. In this case, the film on the outer surface of the bag is a film that softens at a low temperature such as polyolefin. Films that do not soften at low temperatures such as polyester and nylon can be bonded via an adhesive. The shape-retaining tape is often fixed to the outside of the bag, but it may be inside, or the bag mouth may be folded in two and the shape-retaining tape is sandwiched between them to adhere or fuse both sides of the shape-retaining tape. Also in this case, the film may be folded outward or inward.
The bag mouth is the tip of the opening of the bag, but does not have to be exactly the tip and may be in the vicinity of the tip.

  The thickness of the shape-retaining tape can be selected in a wide range according to the purpose, but is preferably 0.1 mm to 2.0 mm, more preferably 0.3 to 1.0 mm. The width of the shape holding tape is not particularly limited, but is preferably 1 mm to 20 mm, more preferably 3 to 10 mm.

  FIG. 1 is a perspective view of a bag mouth that is maximally rounded, and FIG. 2 is a perspective view of a bag according to the present invention folded in two and further folded into four. FIG. 3 is an enlarged cross-sectional view of a portion surrounded by a broken line in FIG.

A high-density polyethylene (manufactured by Nippon Polychem Co., Ltd.) having a weight average molecular weight (Mw) of 3.3 × 10 ⁵ and a melting point of 135 ° C. is supplied to an extruder and melt-kneaded at a resin temperature of 200 ° C. Then, the discharged sheet-like melt-kneaded product was rolled into a sheet having a width of 340 mm and a thickness of 6.0 mm by a calender molding machine controlled at a roll temperature of 110 ° C. to obtain a polyethylene sheet.
The obtained polyethylene sheet was rolled at a rolling ratio of 9.4 times using a rolling molding machine (manufactured by Sekisui Koki Co., Ltd.) heated to 120 ° C. to obtain a rolled sheet having a width of 340 mm and a thickness of 0.64 mm.
The obtained rolled sheet was subjected to multistage stretching with a magnification of 1.8 times in a hot-air heating type multistage stretching apparatus (manufactured by Kyowa Engineering Co., Ltd.) heated to 110 ° C., a total draw ratio of 17.0 times, a width of 240 mm, A polyethylene stretch sheet having a thickness of 0.5 mm was obtained.

  In cleaning the theater after the performance, the present invention bag 2 having a width of 70 cm and a length of 90 cm was prepared as shown in FIG. The bag 2 is a bag made of a single layer film of polypropylene, and the shape-retaining tape 1 was obtained by cutting the polyethylene stretched sheet to a width of 1 cm in the resin stretching direction. 3 is a film and 4 is a bag mouth. The shape-retaining tape 1 was fused from the outer surface slightly behind the bag mouth 4. Reference numeral 5 denotes a fused portion between the shape-retaining tape 1 and the bag 2.

  Since the bag mouth 4 can be held in a wide open state as shown in FIG. 1, most of the dust entered the bag 2 simply by throwing it. Thereafter, fine dust was swept away with a scissors and placed in the bag 2. When moving to the next place, if the distance is long, it is inconvenient to carry, so the bag mouth 4 was folded in four as shown in FIG. Of course, it is free to fold in two or eight. Moreover, when it came to the place to clean, the bag mouth 4 was opened again as shown in FIG. 1, and it worked. As a result, work efficiency has been dramatically improved, work time has been shortened by about 1/3 of the conventional work, and operator fatigue has been reduced.

It is a perspective view when the bag mouth of one Example of this invention is opened large. It is a perspective view which shows the state which folded the bag mouth of one Example of this invention into four. It is sectional drawing of the site | part enclosed with the broken line of FIG.

Explanation of symbols

1 shape holding tape 2 bag 3 film 4 bag mouth 5 fusion part

Claims (4)

A bag capable of retaining the shape of a bag mouth, wherein a plastic shape-retaining tape is fused or bonded along the bag mouth of the plastic bag. The shape-retaining tape is a plastic tape that is rolled and stretched in the length direction at a magnification of 10 to 40 times. When bending any part, it can be easily bent to an arbitrary angle and then corrected to a different bending angle. The bag which can hold | maintain the shape of the bag mouth of Claim 1 which can hold | maintain the previous bending angle until it is added. The bag capable of holding the shape of the bag mouth according to claim 1 or 2, wherein the shape holding tape is a tape mainly composed of polyolefin. 4. The bag capable of holding the shape of the bag mouth according to claim 1, wherein a shape holding tape is fixed to the outside of the bag mouth.

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