JPH01139345A - Easy-to-open bag and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an easy-to-open bag without impairing the cosmetic quality pleasant to the touch and eyes, by preforming a plurality of slits in the heat seal portions of a composite film and heat sealing said seal portions at sealant- fusion temperature. CONSTITUTION:Two sheets of composite polyolefin film 1 are continuously fed in overlapping relationship with their sealant layers facing each other and slits 2 are formed from the outside on both sealing sides thereof by about 1/3 the width thereof. These slits are formed by a rotary cutter 4 fitted with edges 3. Both sealing sides of the films having the slits in the MD direction are then heat sealed together at sealant-fusion temperature by a heat sealing bar 5. A slit 6 is thereafter formed in the composite polyolefin films 1 perpendicularly to the MD direction. The film portions having this slit 6 are heat sealed by a heat sealing bar 8 as in the MD direction. The heat sealing is thus effected both in the MD and TD directions and the composite polyolefin films having heat sealed portions 9 and 10 in a semi-restorable condition are cut off by a cutter 11 into a bag form.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an easy-to-open bag made of a polyolefin composite film and having a semi-restorable notch in the sealing portion, and a method for manufacturing the same.

2. Description of the Related Art Conventionally, as shown in FIG. 9, the seal portion of a packaging bag has V-shaped, U-shaped, air or serrated notches to facilitate opening.

It is also known to provide perforations or the like to the surface layer base material in order to provide straight-line opening.

However, such packaging bags must be handled with care because if an erroneous tensile force or force majeure from the outside is applied to the notch, the contents may spill out or the notch may expand or progress, resulting in dangerous conditions. Met.

In addition, v) y) Containers whose contents are to be stored for a long period of time, such as foods, have become tougher due to advancements in composite films, so it has been difficult to open the container from any point other than the notch.

For this reason, it is undesirable to provide a large number of cut portions from the viewpoint of appearance, feel, etc.

Problems to be Solved by the Invention The present invention eliminates the possibility of bag breakage due to erroneous tension applied to the notch in the seal part of the packaging bag, makes it easy to open the bag by hand cutting from any position, and has a beautiful texture and appearance. The purpose of the present invention is to provide an easy-to-open bag that does not impair its properties and a method for manufacturing the same.

Means for Solving the Problems In view of the above-mentioned problems, the inventors of the present invention have conducted intensive studies, and as a result, have developed a method in which a large number of cuts are made in advance in the heat-sealed portion of a composite film used for packaging bags, and then heat-sealed. The present invention was completed based on the discovery that the object of the present invention can be achieved by having a heat-sealed portion that is semi-restored in a semi-welded state.

That is, the present invention provides (1) an easy-to-open bag having a large number of semi-restored cuts at regular intervals and in the same direction in the sealed portion of a packaging bag made of a polyolefin composite film; and (2) a sealant layer of a polyolefin composite film. When manufacturing bags by stacking the bags so that they face each other, a large number of cuts are made in advance at regular intervals and in the same direction in the sealing part of the bag, and then the sealing part is fused with the sealant. The gist of this invention is a method for manufacturing an easy-to-open bag characterized by thermocompression bonding at high temperature.

The polyolefin composite film of the present invention consists of at least a main layer of polyolefin that also serves as a sealant layer, and at least one layer of another laminate material that is more heat resistant than the polyolefin.

The polyolefin 4 layer may be made of homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1,4-methymupentene-1, or other monomers containing these α-olefins as main components. or a mixture of these polymers. Among these, density α935f
/- or above, MI 0.5 to 20 f710 min, and the degree of crosslinking constitutes a crosslinked layer/uncrosslinked layer/crosslinked layer in the thickness direction of the film, and the gel fraction (boiling point) of the crosslinked layers on both sides is Weight % of insoluble part extracted with p-xylene)
is 20 to 70%, the gel fraction of the uncrosslinked layer is 0%, the composition ratio of each layer is in the range of uncrosslinked layer, two crosslinked layers on both sides = 1: α 1 to 10, the stretching ratio is 3 times or more in one direction, A biaxially oriented polyethylene film having an area magnification of 9 times or more is preferable from the standpoint of film resistance, transparency, and moisture resistance. Methods for producing such cross-linked stretched polyethylene films are disclosed, for example, in Japanese Patent Application Laid-open Nos. 59-174322 and 61-74819.

On the other hand, other laminated materials laminated with the polyolefin layer include paper, aluminum (Az)! , cellophane, heat-resistant resin film, μm, e.g. polyester-1-polyamide,
Examples include films made of ethylene-polyvinyl alcohol copolymer, polyimide, polyparabanic acid, etc., and non-woven fabrics made of synthetic resin.

The composition of the polyolefin composite film is 1, 2 layers with a polyolefin layer, a sealant layer and other laminated materials, polio,
Basics such as 3 layers with a V-fin layer as an intermediate layer, a sealant layer on one side and a laminated material on the other side, or 3 layers with a laminate layer as the intermediate layer, a polyolefin layer on one side and a sealant layer on the other side, etc. However, it is also possible to add layers to these. In addition, when providing a sealan layer separately from the polyolefin layer, for example, low density polyethylene (LDPE), linear low density polyethylene (L, LDPK), ethylene copolymer,
Non-stretched films such as polypropylene and propylene-ethylene copolymers are used.

The method for producing a polyolefin composite film is carried out by laminating the above-mentioned layers by a wet lamination method, a dry lamination method, an extrusion lamination method, or the like using an adhesive. ' The easy-to-open bag of the present invention has widths at regular intervals, preferably about 2 to qm, from the outside of the sealed part, preferably from the outside to about the seal width h, in the same direction, preferably in the vertical and horizontal directions of the bag. It has semi-assembled cuts parallel to each direction. This semi-assembled state refers to a state in which the laminated materials of the polio and reflexine composite films are not connected to each other at the cut portions, but are connected by filling the gaps between the cuts with the molten sheet. That is,
Since the laminated material does not have thermocompression bonding properties, the notch in the thermocompression seal is not restored, but only the sealant layer is restored, so when considering the entire body bag, it can be said that the notch in the seal part is in a moderately restored state. . The shape of the easy-open bag may be any shape, such as a three-sided sealed bag, a four-sided sealed bag, or a pillow bag.

Next, a method for manufacturing an easy-open bag will be described based on an example shown in the drawings. FIG. 1 is a schematic plan view showing the manufacturing process of a four-sided seal bag of the easy-to-open bag of the present invention. The polyolefin composite film 1 is continuously supplied by stacking two sheets with the sealant layers facing each other, and cuts 2 are made from the outside of the sealed portions on both sides. This incision can be made using a rotary cutter 4 having a cutter blade 3 as shown in FIG. 2, or the like. Next, the seal portions on both sides in the longitudinal (MD) direction having the notches are thermocompression bonded using a thermocompression bonding bar 5 at the melting temperature of the sealant.

Next, a cut 6 is made in the polyolefin composite film 1 in a direction (TD) perpendicular to the MD force direction.

This incision can be made using a vertical movable cutter 7 or the like having a cutter blade 3' embedded therein as shown in FIG.

This portion of the notch 6 is thermocompression bonded by a thermocompression bonding bar 8 in the same manner as in the MD force direction.

The polyolefin composite film which has been thermocompression bonded in both the MD force direction and the TD force direction and has thermocompression bonded seal portions 9 and 10 in a semi-restored state is cut by a cutter 11 to form a bag as shown in FIG.

FIG. 5 is an enlarged cross-sectional view of the cut portion of the polyolefin composite film, and the figure is the cut portion of the laminate. Although this cut portion A is a gap on the order of microns, it is not fused at the above-mentioned thermocompression sealing temperature, so the cut portion A is filled with molten sealan a and restored as shown in FIG. In other words, the state is in a medium restoration state.

In addition, in the above manufacturing method, the selection of the polyolefin composite film, the method of cutting the film, the position, interval, direction, method of thermocompression sealing, etc. may be appropriately selected depending on the purpose and use. Moreover, the shape of the bag can be applied to various shapes such as a pillow type bag as shown in FIGS. 7 and 8. Since the reference numerals correspond to those in FIGS. 1 to 4, a description of each device will be omitted.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to examples, but the present invention is not limited to these examples. In addition, % in an example represents weight, and the test method is as follows.

(1) Moisture permeability: JIS Z0208B method (2) Haze: JIS K6714 (3) Gel fraction: ASTM D2765A method (
4) M I: J I S K 6760 Example 1 High-density polyethylene (density α9579/at', M■1
．． of/10 minutes,) and crosslinked by electron beam irradiation (gel fraction (%) = crosslinked layer / uncrosslinked layer / crosslinked layer = 5010150. Crosslinked composition ratio = crosslinked layer: uncrosslinked layer: crosslinked layer = 1:1.75 = 1) at 127°C, MD direction
TD direction = 4 x 6 times stretched high density polyethylene biaxially stretched film (BOHD film) with a thickness of 20μ
Ta. This film has a haze of 2.7% and a moisture permeability of 3.6f.
/ m” / 24 hrs.

Next, after applying a urethane adhesive to this BOHD film, it was bonded with KT foil (9μ), and then LLD PE film (30μ) was applied on At foil in the same manner.
BOHD film / kt ffi, /
A composite film of LL D PE film was obtained.

This composite film is stacked so that the LLDPE film surfaces face each other, and cut from the outside with a cutter as shown in Fig. 2 at a width corresponding to the seal area around the bag body, with a gap of 311 mm.
Parallel cuts were made in the longitudinal and transverse directions at 11 m. Next, this sealed portion was thermocompressed for 1 second using a sealing bar at a temperature of 160° C. to obtain a bag whose periphery was heat-sealed.

This bag could be opened easily and straightly by hand from any position in the vertical or horizontal direction, and the cut was clear. Also, heat seal strength 2-5 k<9715
It had sufficient strength at am.

Example 2 In Example 1, except that a polyethylene terephthalate (PETP) film (12μ) was used instead of the At foil,
A composite film was manufactured and a bag was made in the same manner as in Example 1 to obtain a bag.

This bag could also be opened easily, straightly and clearly by hand from any position in the vertical and horizontal directions. Further, it had sufficient heat seal strength of 2.8kll/15+w.

Example 3 The BOHI) film of Example 1 was used as the intermediate layer, and Example 2
A bag was produced in the same manner as in Example 1 using a composite film in which the PETP film was laminated on one side and the LLDl)E film was laminated on the other side.

The obtained bag could be easily opened straightly and clearly by hand from any position in the vertical and horizontal directions. Further, the heat sealing strength was AOkle/15■, which was sufficient.

Example 4 After applying a urethane adhesive to pg'rp film (12μ), it was dry laminated with the BOHD film (20μ) of Example 1 to form pg'rp film/BO! (A composite film of D film was obtained.BO4 of this composite film
A sealant was applied to the surface of the D film, and bag manufacturing was carried out in the same manner as in Example 1 to obtain a bag body.

The heat seal strength of the obtained bag was 0.7 to 9/15m.
m, and the package could be easily opened straightly and clearly by hand from any position.

Example 5 PFTP film (12μ), At foil (9μ) and LL
DPE film (30μ) was dry laminated in the same manner as in Example 1 to form PETP film/At foil/L L
A composite film of DPE film was obtained. Using this composite film, bag making was carried out in the same manner as in Example 1 to obtain a bag body.

The heat-sealing strength of the obtained bag was 3 U/15 snow, and although it could be easily opened by hand from any position, it could not be cut in a straight line.

Effects of the Invention The easy-open bag of the present invention does not require searching for a notch unlike conventional bags when opening, and can be easily opened from any position on the bag. Furthermore, since the cut is restored to a semi-welded state, the cosmetic appearance is not impaired, and the bag does not break due to erroneous tension being applied to the cut. Furthermore, when a polyethylene V-stretched film in which the degree of crosslinking decreases inward in the thickness direction of the film is used as a composite film, it becomes possible to cut straight and clearly in the vertical or horizontal direction of the bag. Prevents contents from spilling when opened.

[Brief explanation of the drawing]

FIG. 1 is a conceptual plan view of the manufacturing process of the four-sided seam easy-open bag of the present invention, and FIGS. , side view, general view, and Figures 3 (a), (b), and (c) respectively show examples of vertically operating type cutting cutters.
The figure is a conceptual diagram showing an example of a four-sided sealed easy-to-open bag, Figure 5 is an enlarged sectional view of the cut portion of the composite film, and Figure 6 is an enlarged cross section showing the original state of the cut portion of the composite film. 7 is a conceptual plan view of the manufacturing process of a pillow-type easy-to-open bag, FIG. 8 is a conceptual diagram showing an example of a pillow-type easy-to-open bag, and FIG. 9 is an example of a conventional incision. It is a conceptual diagram. DESCRIPTION OF SYMBOLS 1... Polyolefin composite film, 2... Cutting depth (MD), 3... Cutter blade, 4... Rotating cutter, 5... Thermocompression bonding par (MD), 6... Cutting depth (' I
'D), 7...Vertical movable cutter, 8...Thermocompression bonding par (TD), 9.10...Thermocompression bonding seam μ part, 11...
・Cutter, A...Laminated material cut part, a...Melted seahund part, ■...■ type cut, Machining...work type cut, U...U type cut

Claims (2)

[Claims] (1) An easy-to-open bag comprising a polyolefin composite film having a large number of semi-restored cuts in the same direction at regular intervals in the sealed portion of the packaging bag. (2) When manufacturing a bag by stacking the sealant layers of polyolefin composite films so as to face each other, a large number of cuts are made in advance at regular intervals and in the same direction in the sealed portion of the bag, and then the sealed portion is . A method for producing an easy-to-open bag, characterized by thermocompression bonding at the fusion temperature of the sealant.