JPS6382965A - Easy-open bag - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an easy-to-open sealed bag that can be easily opened with the force of fingers.

[Prior Art] In recent years, plastic films and laminated films of plastic and other materials such as metals such as aluminum foil and paper have become lightweight, have excellent airtightness, high strength, and are convenient to handle. Because it does not require adhesive and can be simply heat-sealed, it is used in sealed bags for a wide variety of products such as liquids, powders, pastes, solids, etc., such as food, medicine, and small items.

These sealed bags have the problem that the advantages of the material they are made of result in resistance to tearing when the bag is opened, making them difficult to tear. Although the film used for sealed bags is strong, once a scratch occurs, it tends to propagate easily. Therefore, if you make a scratch on the edge of the bag in advance and use this as a tear opening to pull it, it will cause damage to your hands and fingers. It can be opened with just the power of.

For this reason, a cut (notch) with a length of 2 mm or more in the transverse direction is made in advance on the edge of the film at the fused portion, or a cut in the shape of a 7 (V-notch) is made in advance.

[Problems to be solved by the invention] However, the bag with the above-mentioned notch,
There is a problem that there are many variations, and while some tear easily, there are also a considerable number of those that are pecked during tearing and require bending force.

[Means and effects for solving the problems] The present invention has been made in view of the above points, and it is possible to reliably and easily tear the product in any way without being poked during the tearing process. The purpose of the present invention is to provide an easy-to-open sealed bag that can be easily torn.

That is, according to the present invention, there is provided a bag formed by heat-sealing the edges of a composite film having at least one base layer and at least one heat-sealing layer, the base layer comprising: The base layer is a 2M composite film made of a thermoplastic resin harder than low-density polyethylene, biaxially stretched 1.5 times or more in both the vertical and horizontal directions, and bonded together by hot melt pressure. are arranged so that the orientation lines indicating the orientation direction of the bags intersect at an angle of 0° to 20°, and scars penetrating at least the base material layer are provided at the edge of the heat-sealed portion of the bag. An easy-to-open bag is provided.

The easily openable sealed bag of the present invention is obtained by hot-melt-pressing a composite film having at least one base material layer and at least one heat-sealing layer. and,
The base material layer is made of a thermoplastic resin that is harder than low-density polyethylene.

Here, "harder than low-density polyethylene" means that the Shore hardness (JIS Z 224B) is greater than that of low-density polyethylene.

Specific examples of thermoplastic resins that can be used as the base layer include polyamide (nylon) such as 6-nylon and 6B-nylon, polyethylene terephthalate (PET),
Examples include polyesters such as polybutylene terephthalate (PBT), biaxially oriented polypropylene (OPP), hard vinyl chloride resin, polystyrene, polyacetal, and polyvinyl alcohol.

The base material layer of the present invention is obtained by biaxially stretching the thermoplastic resin film described above by 1.5 times or more in each of the vertical and horizontal directions.

Since such a base material layer is strong, it is naturally difficult to begin to tear it with the force of fingers.

The heat sealing layer of the present invention is formed of a material that melts with heat during sealing. Such materials include low-density polyethylene [high-pressure polyethylene (LDPE), low-pressure linear low-density polyethylene (L-LDPE)], olefin resins such as stretched polypropylene (unstretched PP),
Ethylene-vinyl acetate copolymer (EVA), ethylene ionomer (IR), etc. are used. The heat fusion temperature varies depending on the pressing pressure, pressing time, film thickness, type, etc., but is usually 8° to 180°C, usually 12° to 150°C.
Preferably, the melting is carried out at a temperature of 0.degree. C. and the melting state is at least half melted.

The heat-fusible layer may be formed of the above-mentioned heat-fusible material alone, and incyanate-based materials often exhibit excellent properties as anchor coating agents for increasing adhesive strength. .

The heat sealing layer preferably has a lower tensile strength than the base material layer, and it is also preferable that the heat sealing layer has greater tear resistance than the base material layer. Here, tear resistance is JIS
Refers to the tear resistance for notched samples measured by the method based on P 8116.

Assuming that the base material layer and the heat-adhesive layer are formed by selecting materials having the above strength range, the thickness ratio of the base material layer: the heat-adhesive layer is 5:1 to 1.
:10 is preferable. More preferably the base material thickness is 1° to 50°
ILm, heat-sealing layer thickness 1° to 100 #LI11, total thickness 2° to 150 p, and ra are preferred because they provide a good balance between easy opening and bursting resistance. In other words, it is easier to tear from the part of the scar that penetrates the base material, and the presence of the heat-sealed layer in the scar part prevents the tear from spreading quickly and carelessly, preventing carelessness during transportation and handling. Bag breakage is prevented.

It is preferable to use a film of a resin having barrier properties, strength, and thermal properties such as polyester resin or polyamide resin for the base material layer, or a laminated film containing at least one layer thereof, since the bag becomes a sealed bag that can be applied to advanced packaging. A laminate of aluminum foil and a plastic layer, or a film in which a thin metal film such as aluminum is formed on a plastic film by vapor deposition, sputtering, ion blasting, etc., is also preferred as a base material layer with good barrier properties. Also, for example, polyester, polyamide.

A laminated film in which a vinylidene chloride barrier layer is further laminated on a plastic layer such as polypropylene is also preferred.

The composite film forming the easy-open sealed bag of the present invention can be manufactured by the following method.

■ A method of laminating a heat-adhesive layer on a base material using the dry lamination method.

■　Method of extruding a heat-adhesive layer and laminating it on a base material.

■ A method of sand-laminating a heat-sealing layer onto a base material via an intermediate bonding layer such as polyethylene or unstretched polypropylene.

As the thermal adhesive layer used in the dry lamination method (2), LDPE, unstretched PP, L-LDPE, and ethylene ionomer are preferable.

LDPE film, L-LDPE film, unstretched EV
A film, ethylene ionomer film, etc. are preferred.

As the thermal adhesive layer used in the sand lamination method (2), LDPE film, L-LDPE film, unstretched EVA film, and unstretched PP film are preferable.

The base material layer of the present invention has a thickness of 1.5 in each of the vertical and horizontal directions.
It is stretched by at least 2 times, preferably 2 times or more, and more preferably 3 times or more.

The orientation line indicating the orientation direction is determined by measuring the molecular orientation using a polarized fluorescence photometer, and determining the maximum orientation direction and the direction perpendicular thereto as the vertical orientation line or the horizontal orientation line.

Generally, the orientation direction does not strictly match the stretching direction in the film manufacturing stage. After melt extruding thermoplastic resin from T-Guy, NO (Mach 1neDire
tion) direction and TD (Transvers Di)
First, if we look at the state during extrusion, in order to obtain a product with a uniform thickness, the thermoplastic resin discharge port should not be uniform, but rather slightly stretched as shown in Figure 1. It is adjusted to a distorted shape. Therefore, the thickness of the film that comes out of the T-die is almost constant, but
Because the discharge speed when the molten resin is discharged differs in each part of the T-die, the temperature distribution in each part of the film is uneven, which affects the subsequent stretching, and the orientation direction of the stretched film. As shown in FIGS. 2 and 3, the stretching direction (X-X direction, Y-Y direction) should not coincide with the stretching direction.

For example, when making a bag of a film as shown in Figure 2, the conventional Ichisaka three-sided seal bag making machine folds the film in half, which has a heat-sealing layer on the base layer. In order to seal the three sides by overlapping the heat sealing layers, the orientation lines of the film on the top surface and the film on the bottom surface of the bag do not match, as shown in FIG. 4. In addition, such a phenomenon is
The same problem occurs when a sealed bag is manufactured by cutting the original composite film into separate pieces without folding it in half. That is, since it is necessary to seal the heat-sealing layers with the heat-adhesive layers inside, the film on one side is always inverted and sealed, so the orientation directions of the film on the top surface of the bag and the film on the bottom surface do not match.

If the orientation directions of the base material layers differ between the top and bottom surfaces of the bag, the other base material layer will block the tearing of the base material layer on one side, and this blocking effect will be This is most noticeable in the heat-fused area where the material layers are bonded together via the heat-fused layer. Therefore, even if you insert an ennotch or a V-notch into the heat-sealed edge of such a bag, the heat-sealed part will poke it, and it will take more force to tear it apart. If the film is torn in two directions, the top and bottom films will be torn in different directions after passing through the fusion zone, as shown in FIG. 5 out of 5 are tear parts.

On the other hand, in the present invention, two layers of composite film bonded together by heat-fusion pressure are formed so that the orientation lines indicating the orientation direction of the base layer intersect at an angle of 0° to 20° (shown as 0 in FIG. 4). ) so that they intersect. This intersection angle θ is 0
° ~ 15 ° is preferred, 0 ° ~ 5 ° is more preferred, 0 °
It is more preferably between 0° and 2°, and most preferably 0°, that is, when the orientation axes are perfectly aligned.

In the present invention, the intersection angle of orientation lines simply means the intersection angle between the straight lines when the orientation lines are straight lines, and the intersection angle between the straight lines when the orientation lines are curved lines (for example, see FIG. 8). The angle of intersection between tangent lines.

When there are two or more base material layers in the composite film forming the bag, it is necessary to arrange them so that the orientation lines of all the base material layers intersect at an angle of 0° to 20°.

In order to reduce the intersection angle of the orientation lines to the above range, the following method is adopted.

■ As shown in Figure 6, after biaxial stretching orientation, the film running direction (machine direction = Machine Direction =
MD) is cut into predetermined lengths L, one of them is moved in parallel (not inverted), and in Fig. 6, al, bl, and a are cut.
2 and b2, respectively.

■ As shown in Figure 7, width direction (transverse direction = Transve
rseDirection = TIE), and divide it into appropriate widths, so that the intersection angle of the orientation lines is the smallest value.
Either move them in parallel or invert them and overlap them as shown in Figure 8.

In the above method (■), when the film production reaches a steady state, the same orientation state appears continuously in the film running direction, so if the length is kept constant and overlapped, the above-mentioned intersection angle will be almost the same. It can be made close to Oo.

In method (2) above, the orientation direction of the biaxially stretched films is checked using a polarization fluorometer, and the films are superimposed by being translated or reversed so that the intersection angle of the orientation axes becomes the small value mentioned above. When applying method (2), if the orientation line is in a certain diagonal direction as shown in Figure 7, for example, cut the film in half in the width direction, and cut one film A in the width direction. If they are moved in parallel and overlapped so that the back surface of A and the front surface of B match, the intersection angle between the orientation line of the base material of A and the orientation line of the base material of B will be a very small value (very small). (close to Oo). In addition, to apply method (2) when the film is oriented almost symmetrically as shown in Figure 8, it is necessary to fold or cut the film along the dashed line in the center to divide the film into two equal parts. By overlapping the back sides, the intersection angle can be reduced. Furthermore, in the case of four or more equal parts, the intersection angle can be made smaller by overlapping the front surfaces or the back surfaces of the films at positions symmetrical to the center broken line.

Although the shape and size of the scar do not matter, it is preferable that a portion of the scar has an acute angle (notch-like) part so as to produce a notch effect. Moreover, as shown in FIG. 9-C and FIG. 10-A, a shape elongated in the direction perpendicular to the longitudinal direction of the composite film is preferable. Figures 10-A to 10-E are plan views for illustrating and explaining the shape of scars, and Figure 10-A is a short line having an elongated shape in a direction perpendicular to the longitudinal direction of the composite film. Figure 10-B shows a triangular scar, Figure 10-C shows a diamond-shaped scar, Figure 10-D shows a star-shaped scar, and Figure 10-D shows a star-shaped scar. Figure -E shows a stipple (dot-shaped) scar.

Moreover, even if the scars are not punched out, they can be created by pressing, scraping, tapping, etc. with a knife or a grating tool as shown in FIG. 11.

f511 Tool shown in figure 1 and protrusion 1 with elongated cutting edge
1, and as shown in FIG.
It is manufactured by making the fully bent part which has been cut and separated from the metal surface 12 stand up, with the base of this pseudo-triangular shape as the central axis, and the protrusion 11 is made to protrude. Note that the cut portion of the metal surface 12 remains as a depression 14. 16 is a ridgeline, and 17 is a raised surface.

The angle formed between the surface of the protrusion 11 on the recess side, that is, the metal surface of the upright surface 15, is preferably 60° or more and 90° or less.

One or more lines of such protrusions are arranged in a linear manner, and the metal is hardened and used. FIG. 13 is a perspective view of a processing roll 18 provided with such projections on its circumferential surface.

When the composite film 2 is pressed with the protrusion 11 as shown in FIG. The composite film on the side is expanded by the raised surface 17, and as shown in FIG. 9-B, the part pushed in by the raised face 15 is straight, and the part pushed in by the raised face 17 is deformed diagonally downward. At the same time as the steps are different, there is also distortion.

In other words, there will be parts with distortion and parts without distortion, and the parts with distortion will remain as internal distortions even when the step difference disappears and the state returns to almost its original state. The strength is reduced due to distortion, and it has the important effect of being easily torn with fingers from the boundary between the distorted and non-distorted parts. Moreover, unlike when cutting with a normal knife, cracks are formed at both ends of the scar, and these cracks have a large cutting initiation effect. 11th as above
The process of creating scratches using the tool shown in the figure is hereinafter referred to as NC process.

FIG. 14 is an explanatory diagram showing an example of processing the composite film 2 using the processing roll shown in FIG. 13.

The processing roll 18 and the presser roll 19 are in contact with each other, and the composite film 2 passes through the contact area between the two rolls, which are rotating in opposite directions at the same circumferential speed. At this time, the composite film 2 is pressed by the protrusion 11 of the processing roll 18, and as shown in FIG.
Scars 6 are arranged as shown in Figures 9-B and 9-0.

20 is the original fabric of the composite film.

The tool for applying the scars is preferably made of a hard material, and in addition to hardened steel, ceramics such as silicon carbide, titanium carbide, and silicon nitride can also be used. In addition, after finishing the tool shape with metal material, CVD method, P
Those obtained by coating with a thin film of silicon carbide, titanium carbide, etc. by the VD method or the like are also preferable because they have excellent wear resistance and do not reduce sharpness.

The bag may be of a three-sided sealed type as shown in FIG. 15, or a four-sided sealed type as shown in FIG. 16. 2]
2 is a vertically fused portion, and 22 is a lateral fused portion. When the fused portion 21 is provided at the outermost edge in this way, the region where the scar group should be provided is the edge of the fused portion. FIG. 15 shows the case where the scar group is provided on the edge line, and FIG. 16 shows the case where the scar group is provided inside the edge line. Also, if there is a part of the film that is not fused on the outside of the fused part of the bag,
Scar groups are similarly provided on the edges of this unfused portion of the film. Therefore, the film according to the present invention has scar groups on both edges over the entire length or locally. However, when using an automatic bag-forming-filling machine for mass production that simultaneously cuts the film in the longitudinal direction and forms two or more bags, several rows of scar groups are formed in the longitudinal direction. As shown in FIG. 17, when groups of square-shaped scars 6 are provided in the vertical and horizontal directions, a four-sided sealed bag that can be torn from any of the four sides is obtained.

Furthermore, there is also a three-sided seal type bag as shown in FIG.

FIG. 19 is an enlarged cross-sectional perspective view of FIG. 18.

In this case, the composite films 2 to be fused are brought close to each other from opposite directions and overlapped, which is a so-called overlap type fusion method, and the fused portion does not protrude from the bag surface. Since the through-scar group according to the present invention is provided at the end edge of the longitudinally fused portion 21, the seal can be cut and opened over the entire width by crossing the fused portion without stopping at the fused portion. Therefore, even if the contents are hard and stick-like or have a width close to the width of the bag, they can be easily taken out.

The position where the scar is placed in the bag of the present invention is within about 5 mm from the edge of the heat-sealed part of the bag, and the interval between the W marks is 1 to 5 mm.
and may be arranged in two or more rows.

The part where the scar group is provided is the part that becomes the edge of the fused part, and is preferably a part 0.5 to 3 +++ m inside the edge line.

The scar group may be in one row or in multiple rows of two or more as long as it is substantially on the edge line. When multiple rows are provided, the width of the scar group is preferably within 5 cm; More preferably, it is within 3.5 mm.

Even if the pitch pattern of the scar as shown in FIG. 9-0 is long, tearing property is exhibited, and the pitch pattern can be made as long as 1, for example, about 5ffl111.

[Example code] Next, the present invention will be explained with reference to Examples.

Example I A polyamide film with a width of 720 mm (Unitika 6 nylon film: Emblem ■ Thickness: 15 ILm) obtained by biaxially stretching using a tenter method after extruding from a T-die. Stretching using a polarized fluorometer Figure 6 was obtained by examining the direction of orientation and connecting it with a line. As can be seen from FIG. 6, the same stretching orientation pattern appeared repeatedly.

The above polyamide film original fabric is 2000 m long and 40 m long.
The film was cut at a point of 00 m, and the first half was designated as film A, and the second half was designated as film B. Then, on the upper surface of A and the lower surface of B, an L-LDPE film (Tojo Ro TUX-FC
1 (thickness: 25 gm) to obtain a composite film that can be bonded by hot melting, and A and B were each wound onto separate rolls.

Next, pay out A and B from each roll, and place the top surface of A (L-LDPE surface) on the bottom surface of B (L-LDPE surface).
The length is 300+a++ using an automatic bag-making machine.
+ 3-sided sealed bags with a width of 200 mm and a seal width of 8 cm were obtained (approximately 20,000 bags).

Put 800 g of tomato ketchup into the bag and seal the opening with a sentinel heat sealer at 160°C for 1 sec.
A four-sided sealed bag was made under the condition of X 2.1 kg/cm2.

MC processing, V-notches, and I-notches were added to both side seals, and tear-openability was examined.

There was no difference between the 14G processing, the V-notch, and the ■-notch, and all were easy to open without any resistance. In addition, it was easy to open the package without any resistance even if it was torn from either the left or right side.

Comparative Example I A polyamide film original film (Unitika 6 nylon film: emblem (multi-thickness 15 pm) with a width of 720 cm obtained by biaxially stretching using a tenter method after extrusion from T-Guy was measured using a polarized fluorescence photometer. Figure 6 was obtained by checking the direction of the stretching orientation and connecting them with lines.As can be seen from Figure 6, the same stretching orientation pattern appeared repeatedly.

On top of the 4000 m long original polyamide film, an L-LDPE film (Tojo Ro
-FC1 (thickness: 25 mm) was formed into a continuous particle layer to obtain a composite film that could be hot-melted and pressed.

4000 m of the obtained composite film was divided into 1/2 in the longitudinal direction to obtain 2000 m rolls A and B, 20 rolls.

Next, roll out A and B from each roll, L-L
Overlap the DPE film sides and use an automatic bag making machine to make 3 bags with a length of 300mm, width of 2001111, and seal width of 8H.
Obtained bags (approximately 2,000 bags).

Put 800g of tomato ketchup in a bag and seal the opening with Sentinel heat sealer at 160℃ x 1.
X 2. A four-sided sealed bag was made under the condition of Ikg/c+a2.

MC processing, ■notches, and ennotches were added to both sides, and tear-openability was examined. All of them had strong tear resistance and were not easy to open, and the hot melt pressure bonded films on the back and front were torn asymmetrically, as shown in FIG. 5, and could not be opened smoothly and easily.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the shape of the opening of the thermoplastic resin discharge port for film molding, Figures 2 and 3 are explanatory diagrams showing the deviation between the orientation direction and the stretching direction of the stretched film, and Figure i4. is an explanatory diagram showing a state in which the orientation lines of the film on the top and bottom surfaces of the bag do not match when the film is made into a bag. Figure 5 shows a tearing state when the directions of the orientation lines on the top and bottom surfaces of the bag do not match. 6, 7, and 8 are explanatory diagrams showing an example of the method for manufacturing the bag of the present invention. Figure 11 is an enlarged perspective view of the surface part of the tool that creates scars, Figure 12 is an explanatory diagram showing the manufacturing process of the tool in Figure 11, and Figure 13 is the
FIG. 14 is an explanatory view showing a state in which the tool shown in FIG. 13 is used to create a scar, FIG. 15 is a perspective view showing a three-sided sealed bag, and FIG.
17 is a plan view showing a film with scratches, FIG. 18 is a perspective view showing a 3-side seal bag of a different type from FIG. Figure 19 is the 18th
1 is an enlarged cross-sectional perspective view of the figure; 1... Stretched film, 2... Composite film, 3...
・Orientation line, 4...I notch, 5...tear part, 6...
・Scar, 7...Composite film width, 8...Cutting line, 9
...Base material layer, IO...thermal adhesive layer, 11...protrusion,
12... Metal surface, 13... Notch, 14... Hollow, 15... Upright surface, 16... Ridgeline, 17... Raised surface, 18... Processing roll, 19... Presser roll, 2
0... Original fabric of composite film, 21... Longitudinal direction fusion part, 22... Horizontal direction fusion part, 23... Discharge port.

Claims (1)

[Claims] (1) A bag made by heat-welding and pressing the edges of a composite film having at least one base material layer and at least one heat-sealing layer, the base material layer being made of low-density polyethylene. A two-layer composite film made of a hard thermoplastic resin, biaxially stretched by a factor of 1.5 or more, and heat-fused to each other, has an orientation line indicating the orientation direction of the base layer between 0° and 20
1. An easy-to-open bag, characterized in that the bags are arranged so as to intersect at an angle of .degree., and have scars penetrating at least the base material layer at the edge of the heat-sealed portion of the bag.