JPH0199827A - Heat fusion bonding of heat high-shrinkable film - Google Patents

Abstract

PURPOSE:To effect heat fusion bonding efficiently without deformation of a highly shrinkable film, by bonding a specific fusion bond setting part under a specific condition. CONSTITUTION:A laminated film F transferred by a transfer device H1 is press hold at its intended heat fusion bonding part G1 with holders 1, 2 and 3. The held laminated film is cut with a cutter 11, and pinch pressed with a heated presser 5, in this case, the holders 1, 2 and 3 are cooled so that the film in the vicinity of the presser 5 may not be deformed by heat of the presser 5. Conditions of heat fusion bonding are composed of a step (a) for effecting heat fusion bonding G onto a laminated film F fed from the arrow direction, a step (b) for delivering the laminated film F to a moving device H2 by the operation of the transfer device H1 (in this step, the next heat fusion bonding intended part G1 is decided), a step (c) for cutting a part little ahead of G1 to obtain a bag F1, and a step (d) for carrying out the cut bag F1 by the transfer device H2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the side edges or The present invention relates to an improved technique for heat-sealing and bonding a highly heat-shrinkable film for bonding the bottom edge.

[Conventional technology]

Thermal melting of high heat shrinkable films to automatically and intermittently fuse the side edges or bottom edges to form bags when two layers of high heat shrinkable flat films are made into bags. The prototype of the bonding method is known. This is disclosed in, for example, US Pat. No. 3,195,285, Japanese Patent Publication No. 45-2567.
4, etc., and disclosed in Japanese Patent Publication No. 45-32513, etc., and is widely known.

The difficulty in heat-sealing this highly heat-shrinkable film is that the heat received directly or indirectly from the heated welding tool causes the film near the joint to shrink or generate shrinkage stress, which causes the melting. Defects such as ``tearing'', ``holes'', ``twitching'', and ``wrinkling'' occur at bonded joints, and if we try to avoid this through temperature conditions, the joints must have the necessary strength. Therefore, in the end, fusion bonding cannot be carried out industrially.As a countermeasure for this problem, the above three inventions have in common that the fusion bonding area of the film is separated by #1 with a relatively narrow width interval. The film is held under pressure with a pair of holders arranged approximately parallel to each other, and a heated welding tool is used to press and hold the film in the middle of the width of the holders to form a molten part and join the film by fusion bonding. As a feature of fusion bonding, the previous two inventions first cut the film in the middle of the film held by a pair of holders before applying pressure with the welding tool. In a later invention, a cooling holder was further provided on both sides of the welding tool within the width interval of the holder to prevent the shrinkage strain of the film from being applied to the fused joint. It discloses the need to take measures to cool and maintain the film so that shrinkage distortion does not occur in the film.

[Problem that the invention seeks to solve]

However, from K, the difficulty in heat-sealing highly heat-shrinkable films cannot be solved by this level of innovation, and in the end, it is necessary to either sacrifice productivity or compromise on insufficient quality. The current situation is that nothing can be done about it. That is, for example, US Pat. No. 3,195,285, Japanese Patent Publication No. 45-2567
In the method of Publication No. 4, etc., the heat shrinkage rate of the film is 20 to 3.
(1 (hot water at 90°C)) can be used for production if the quality of the bag obtained is somewhat unsatisfactory, but the heat shrinkage rate of the film exceeds 30%, for example, 35
-50% (90℃ hot water) level causes "holes", "twitching", and "wrinkles" in the fused joint.
The phenomenon of defective products is unavoidable, and this was
If an attempt is made to solve the problem using the method disclosed in Publication No. 3, etc., there is a problem in that the time required per shot doubles and productivity must be significantly sacrificed. In particular, for highly shrinkable films, the fusing conditions are set at low temperatures, which increases the time required for fusing and bonding, and when trying to make large diameter and long bags, it is difficult to transport the film. It is also necessary to take into consideration the fact that the required opening time is prolonged, and maintaining and improving this productivity presents difficulties unique to highly shrinkable films.

[Means for solving problems]

The key points of the present invention are as follows: L (Regarding welding A located in the middle of the width interval of the film holder) This welding tool substantially controls the formation of a fused part of the film by heating and pressing. Its surface is composed of a convex pressing tool covered with a mold release material and a flat pressure receiving tool whose surface is covered with a elastic elastic body, which cushions the contact surface of the pressing tool and insulates the molten part. 2. (Thus) when forming the fused joint between the two films, the fused joint is fused and fixed to the pressure-receiving tool side in a peelable state, and the holding tool and the pressing tool are connected together. The fused and fixed state is maintained even after the pressure is released, and 3. The fused and fixed portion is then peeled off to obtain a bag-like film.

[Effect]

The effects of fusion-fixing the fusion-bonded portion of the film to the pressure-receiving tool are as follows a), b), and c).

a) To prevent deformation of the film by maintaining the fixed state and to prevent deterioration in the quality of the fusion joint (occurrence of defective phenomena).

b) The role of a) above can be achieved without installing another device for fixation and maintenance, and the quality of the resulting fused joint can be improved by extending the pressing period with the film holder. This phenomenon is caused by the fact that the fixation itself is fixed in one place at the fusion joint, so that one side of the heat shrinkage is caused by one side of the open film edge and the other side of the long film. It is assumed that this is to maintain a reasonable condition for the film, which is absorbed by each film.

C) The essential purpose of this fusion fixation period is to cover a part of the time required for fusion bonding indicated by the target film, but when viewed from the top of the installation, the pressure for fusion fixation is Not only can you shorten the time required, but if you add the ability to transfer the film for the next preparation while it is fused and fixed, you can also shorten the time required for transferring the film. Productivity can be improved when producing shaku bags.

〔Example〕

The contents of the present invention will be explained in detail below using drawings and the like.

FIG. 1 is a conceptual diagram showing a cross section of an apparatus convenient for carrying out the method proposed by the present invention, FIG. 2 is a conceptual diagram showing the contents of film transport in the apparatus of FIG. Figure 3 A)
B)O) is a diagram showing the operation of the device for one shot of the content of the present invention in FIG.

In FIG. 1, the folded cylindrical (two overlapping sheets) film F transferred by the transfer device H1 has a pressing function such as a stopper 4° spring 41 at its fusion-bonding planned portion Gl. , its tip is pressed and held by a holding device consisting of a pair of holding tools 1, 2.3 arranged substantially parallel with a relatively narrow width interval. The film in the holding state is cut by a cutting tool 11 that moves between the holders 1 and 2 with the vertical movement function 12, and at the same time, the film in the holding state between the holders 2 and 30 is cut by a pressing tool in a heating state. It is squeezed by 5. At this time, the holders 1, 2, and 3 are provided with a cooling function so that the heat of the pressing tool 5 does not deform the film in the vicinity thereof. Another measure to minimize film deformation is to arrange the holders at relatively narrow width intervals.

Furthermore, the heating of the pressing tool 5 is kept to the minimum necessary temperature in order to minimize deformation of the nearby film, and to compensate for this, the time required for fusion bonding [melting, pressing, holding, cooling] is reduced. In addition to increasing the length, it is important to increase the pressing force.
Here too, a fluid cylinder 7 is arranged which can provide a pressing force of 13 to 20 kII/-. The welding tool according to the present invention includes a convex pressing tool 5 whose surface is covered with an outbuilding material 6, and a surface of the pressing tool that controls the contact surface contact and heat insulation of the molten part! A flat pressure receiving tool 9 covered with a rubber elastic body 10 is constructed. It is more convenient to arrange a large number of pressure-receiving tools 9 covered with the rubber elastic body 10 in a conveyor-like manner with a predetermined width interval so that the cutting tool 11 protrudes from the width interval when the pressure-receiving tools 9 are at rest. . The combination of the convex pressing tool 5 and the pressure receiving tool 9 covered with the rubber elastic body 10 is advantageous in evenly pressing the entire long joint.
It is also advantageous for forming a fused joint with high peel strength.

The most interesting phenomenon is the pressing conditions, the pressing tool 5, and the pressure receiving tool! By setting the temperature difference between the lock and the elastic body 10 within a certain range, the fused joint can be reliably fused and fixed to the pressure receiving tool 9 side in a releasable state. In the present invention, by fusion fixing of this fusion joint part, [holding,
cooling], thereby improving the quality of the fusion bond, ensuring the film transfer state, and shortening the time required for one shot of the device. It is. For this reason, it is necessary for the fusion fixation to the pressure receiving tool 9 to maintain the fusion fixation state even after the pressure between the holder and the pressing tool is released, and after that, it is necessary to maintain the fusion fixation state at a predetermined place, for example, using a squirrel. It is peeled off at -13 (or 13') to form a bag-like film.

The content of film transport shown in FIG. 2 shows the contrivance of the apparatus shown in FIG. 1, as well as the positional relationship and operation order based on this.

That is, the operation sequence a) is a stage in which the fusion bond G is applied to the film fed from the direction of the arrow, and step) is a stage in which the film is searched for by the transport device 1IH21C by the action of the transport device H1, and at this time, the next step is performed. The part G1 to be fused and joined is determined, c) is the stage where a little tip of Gl is cut to obtain one bag P1, and 2) is the stage where one cut bag F1 is carried out of the apparatus by the action of the transfer device H2. and the planned part Gl is the next fusion joint part OVc
It shows the order of each operation in which a changed stage leads to the next step (a).

Observance of this operation is to align the shape and position of the fusion joints and cut parts of high-shrinkage films, where the transfer state of the film changes depending on the room temperature or ambient temperature. . In this case, the rate-determining conditions are the diameter and length (fold width and unit length) of the bag to be obtained when the film material is constant. In other words, for example, assuming that a bottom seal is placed in a cylindrical film and the bottom seal is pressed at a speed of 60 sheets per minute, the time taken per shot to obtain a bag is 1 second, and this 1 second It is necessary to complete the fusion bonding and cutting-transfer within. If this fusion bonding requires 0.5 seconds, this means that the film transfer can be completed in the remaining 0.5 seconds and cutting and bottom sealing can be done immediately.

In general, increasing speed on a mechanical mechanism is relatively easy.

However, since the film has poor rigidity and is difficult to maintain a flat shape, it is not always possible to follow this mechanical speed increase. For example, even if it were possible to increase the transport speed without compensating for stiffness by adding vertical pleats to the film, it would be impossible to shorten the transport time if it took time for the film to return to its flat state at the destination. These things happen even when the film transfer is completed in 0.5 seconds, when the target is a bag with a fold width of 43B and a unit length of 70m, and when the target is a bag with a fold width of 430fl and a unit length of 700U. It will be understood that the latter method, which has a larger folding width and larger unit length, is incomparably more difficult.

FIG. 3) is a one-shot diagram of the device operation of the content of the present invention in FIG. 1.

With the apparatus shown in Figure 1 of this company, Realon S [manufactured by Asahi Kasei Corporation, trade name of a commercially available five-layer highly shrinkable bag-like film],
Thickness 60 microns, folding width 430fi, unit length 7000
2 is a diagram showing the operation of the apparatus for each shot in the case where the fusion bonding part G of FIG. 2 is applied to the C1 cylindrical film to be produced and the film is made into bags at a speed of 60 sheets per minute. The time required for fusion bonding and the transfer time are each 0.5 seconds.

First of all, Fig. 3 0) shows the comparative method of fusion bonding within the required time.
holding and cooling] are mostly film holders 1 and 2.
．． The diagram of the device operation when trying to stabilize the fusion joint by extending the presser action in step 3, @3 A) shows the amount of [holding and cooling] within the above-mentioned time required for fusion joining. This is a diagram of the operation of the device when the part is covered by the fusion fixation of the fusion joint part, and the pressing operation part after the film holder t, 2.3 is replaced with the fusion fixation, Fig. 3B) In principle, this is just the addition of transporting the fused joint for a length of time with the fused joint fixed in place (Fig. and [holding,
Due to the combination of cooling] and the time required for transportation,
This figure shows that the time required for one shot has been reduced. In addition, the bag making conditions and the quality of the fused joints in Figure 3 A), B), and O) are summarized in Table 1.

Margins below [Effects of the Invention] By having the above-described structure, the present invention can maintain and improve the quality of the fused joint and its productivity during bag making using a highly shrinkable film. The present invention is particularly effective in improving productivity when manufacturing large-diameter and long bags, which has been particularly difficult, and is thus an excellent invention useful to industry.

4. Brief explanation of the drawing
Figure 1 shows in cross section a device useful for carrying out the invention.
Figure 2 is a schematic diagram of the process, Figure 3 is a diagram of the operation of the castle equipment, respectively.

F; Two overlapping films, oi; Part to be fused and joined, 1, 2, 3; Holder, welding piece [5; Pressing tool, 9;
pressure receiving tool], 6: mold release material, 10: Zam elastic body, 11: cutting tool, G: fusion joint, 13: peeling tool, Hl, H2: transfer device, Fl: bag-shaped film.

Patent applicant: Asahi Kasei Industries, Ltd. Rattan 3 diagram (A) 0 0.2 04 0.6 0.8 1' (excerpt) 1 shot given 94/￥r0B1 Figure 3 (B) 0 02 0.4 0.6 0.8 1 (story) 1 shot depth #B1 Figure 3 (C) OQ2 0.4 0.6 0.8 1 (1F)

Claims (1)

[Claims] A pair of holders arranged approximately in parallel with a relatively narrow width interval is used to press and hold the parts of two superimposed highly heat-shrinkable films that are sequentially and intermittently moved and are to be fused and bonded.
A heated welding tool is used to pinch the film in the holding state in the middle of the width of the holder, forming a molten part in the film that follows the shape of the welding tool, and welding and joining the two films together. In the bag-forming method, the welding tool is heated and pressed to substantially form the melted part of the film, and the surface of the welding tool is covered with a release material to cushion the contact surface of the convex pressing tool and to form the melted part. Its surface, which controls heat retention, is composed of a flat pressure-receiving device covered with a rubber elastic body, and when forming the fusion bond between the two films, the fusion-bonded portion is placed on the pressure-receiving device side. The film is fused and fixed in a removable state, and the fused and fixed state is maintained even after the pressure between the holder and the pressing tool is released, and the fused and fixed portion is later peeled off to obtain a bag-shaped film. A heat fusion bonding method for highly heat-shrinkable films characterized by