JPS6329540Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Field of application of idea]

This invention is a press through package.
The present invention relates to a die for single-stage molding of pockets (hereinafter referred to as "PTP").

[Conventional technology and its problems]

(Prior Art) As is well known, PTP is produced by first heating a film or sheet (hereinafter collectively referred to as "film") of a thermoplastic synthetic resin such as polyvinyl chloride or polypropylene, and then dicing it into large numbers using a die. After forming regular recesses (pockets) and filling the recesses with articles such as tablets and capsules, the entire opening side of the film, etc. is lined with a lining made of the same resin as the film, etc. Manufactured by heat sealing with aluminum foil. Therefore, an important issue in this packaging process is ``How to form recesses of uniform thickness in a heat-softened plastic film.'' As is well known, in films made from polyvinyl chloride (PVC) amorphous resin, the plasticization temperature (T _p )
Due to the large temperature difference between and the melting temperature (T _f ),
Even by known vacuum forming means, especially a simple straightening method, a pocket portion having a practically uniform thickness except for the corner portions can be formed. However, with films made from crystalline resins such as polypropylene (PP), it is difficult to make the thickness of the bottom and side walls of the pocket almost uniform, let alone the corners, and it is difficult to make the thickness of the bottom and side walls of the pocket almost uniform, for example by using normal vacuum forming methods. In such cases, it is difficult to make the thickness of the bottom of the pocket more than 20% of the original film. This is the same even when a compressed air method is used instead of a vacuum method. (Problems with the Prior Art) Therefore, various proposals have already been made for the purpose of making the wall thickness of PTP films uniform. In forming pockets, a method was proposed in which the pocket part was formed in two stages using two types of rolls having two types of recesses, shallow and deep, as described in Japanese Patent Publication No. 55-111222.
The publication discloses a two-step molding method in which a polyolefin film is first heat-formed into a pocket smaller than the actual pocket shape, and then re-molded to the actual pocket size when cooled. However, since all of these methods are two-step methods, both the equipment and operation are complicated. Furthermore, it is unclear whether or not it is possible to form an oval or elliptical pocket with uniform wall thickness, which is the aim of the present invention, by using these methods. In view of the above circumstances, the applicant has previously filed a patent application filed in
The invention related to No. 53208 was proposed, and the thickness of the side wall part of the pocket part was increased to about 1/2 of that of the bottom part by using a combination of embossing with a plug and appropriate stretching on the PP film. revealed that he would get it. However, even in this case, the wall thickness at the corner part (the boundary between the side wall and the bottom part) tends to be thinner than other parts, and this disadvantage reduces the airtightness of the package and may cause cracks in some cases. It was something like that. The above has been an overview of known techniques for molding circular pockets, but the longer and shorter diameters of pockets for rugby ball-shaped irregularly shaped tablets and capsules, which have been in increasing demand in recent years, are different. In particular, there was a tendency for the thickness to decrease further on both sides in the major axis direction, and this was an important unresolved problem in PTP manufacturing technology.

[Purpose of invention]

In view of the above circumstances, the present invention is designed to reduce the thickness at the corner part by a one-step method, regardless of the film material used, especially in oval or oval pockets by adding innovation to the shape of the die. Although the general objective is to obtain a pocket without any pockets, a particularly important objective is to substantially equalize the wall thickness of each part of a PTP pocket using a PP film.

[Means to achieve the purpose]

(Summary) In order to achieve the above objectives, this invention
A single-stage PTP pocket molding die is a die equipped with a plurality of recesses having oval or elliptical openings regularly formed on the die surface, and each recess has a plurality of recesses that cut the opening surface perpendicularly. The cross-sectional shape along the surface exhibits a continuous concave arc surface, and the ratio of the short axis to the long axis of the opening surface is 2.5 or less, and the depth is approximately the same as the short axis or slightly larger than that. It is characterized by The details of the present die will be explained below with reference to the drawings. (Structure) FIG. 1 is a plan view illustrating one recess of the die of the present invention, and FIGS. 2 and 3 are respectively shown in FIG.
4 is a schematic sectional view illustrating the process of adding a pocket to a PP film by combining the die of FIG. 1 with a punch of the same shape, and FIG. A schematic cross-sectional view illustrating the process of vacuum forming a PVC film using a die with air intake holes in the recesses shown in Figures 1 to 3. Figure 6 is a modification of the recesses in Figures 1 to 3. FIG. 2 is a diagram similar to FIG. The recess 2 is formed on the upper surface of the die 1 to have an elliptical opening plane (FIG. 1), and has an inner wall 2a.
are carved in a continuous concave arc shape along all the surfaces that vertically cut the opening surface 2b of the recess (FIG. 2). The shape of the recess 2 in the die of the present invention should have an oval or oval planar shape. The ratio of its short axis to long axis is preferably selected within a range of approximately 2.5 or less. If the major axis exceeds 2.5, it becomes difficult to make the thickness uniform even if the internal shape of the recess is precisely designed. The depth of the recess 2 is preferably approximately the same as or slightly deeper than the upper minor axis. Furthermore,
The central portion of the bottom of the recess may effectively form a facet 2c, as shown in FIG. In addition, when forming a crystalline resin film, the punch used together with the die is naturally given an external shape corresponding to the recess, but the thickness of the film used should be taken into account when determining the major and minor axes. be. The die in the present invention is configured in a flat or rolled shape depending on the configuration of the molding machine used.
Generally, when using vacuum or pressure forming means,
Although either type of die can be used freely, it is technically difficult to employ a roll die when using a press method suitable for forming crystalline resin films.

[Effect]

Now, as shown in FIG. 4, when the plasticized PP film F is pressed using the punch 3 having the plug 4 with the outer shape corresponding to the recess 2 above,
The film F is stretched in the order from a to c in the figure. At this time, since both the recess inner wall 2a of the die 1 and the outer wall 4a of the plug 4 are formed in a continuous arc shape, an average pressing action is exerted on the abutment area between the film F and the plug outer wall surface 4a, and thereby Since the film is subjected to an average stretching action, not only is the decrease in the thickness of the pocket side wall portion which was a drawback of the applicant's prior invention prevented, but also the molded pocket portion P has corners. Because there is no wall thickness at the corners like in conventional pockets, there is no need to worry about the wall thickness becoming thinner at the corners. The above is a description of forming a crystalline film using a press method, but the object of the present invention is not necessarily limited to a press method that uses a combination of punches. Even in the case where the vacuum forming means is applied, as the film to be formed F hangs down due to suction, as shown in FIG. , a pocket portion P having a substantially uniform thickness including the corner portions is formed. As a result of the thickness of the pocket being evened out in this way, cracks will never occur without strictly regulating the working conditions or conditions, and it will be possible to use thinner film for packaging than before. This brings about many practical advantages. In particular, in irregularly shaped recesses where the major axis and minor axis of the pocket portion differ by 1:2 or more, which is the subject of the present invention, the wall thickness of the pocket portion may be Although it is particularly difficult to achieve uniformity, according to the present invention, the film in the mold can slide in all directions, so the film in the short axis direction is subject to the strongest tension, while the film in the short axis direction is subject to the strongest tension. As a result of the compensating movement, the film undergoes stretching in a nearly macroscopically isotropic manner, so that the wall thickness of the resulting pocket is highly averaged and virtually uniform, similar to that of a circular recess. Conditioning is obtained. For this reason,
The die of this invention is most suitable for packaging rugby ball-shaped tablets or capsules, which have been widely used recently.

[Effect of the idea]

As described above, according to the present invention, the drawbacks of the known PTP pocket single-stage molding dies can be completely eliminated, thereby achieving the effect of significantly advancing PTP manufacturing technology.

[Brief explanation of drawings]

FIG. 1 is a plan view illustrating one recess of the present die, and FIGS. 2 and 3 are respectively shown in FIG. 1 and line A.
4 is a schematic sectional view illustrating the process of adding a pocket to a PP film by combining the die of FIG. 1 with a punch of the same shape, and FIG. A schematic cross-sectional view illustrating the process of vacuum forming a PVC film using a die with air intake holes in the recesses shown in Figures 1 to 3. Figure 6 is a modification of the recesses in Figures 1 to 3. FIG. 2 is a diagram similar to FIG. The meanings of the symbols in the figure are as follows: 1: die; 2:1 recess; 5:1 intake hole;
2a: 2 inner wall, 2b: 2 opening surface, 2c: 2 bottom small plane), 3:1 punch, 4:3 plug,
4a: Outer wall of 4; F: Film; P: Pocket of F.

Claims (1)

[Scope of utility model registration request] In a die equipped with a plurality of recesses having oval or elliptical openings regularly formed on the die surface, each recess is a continuous concave cross-sectional shape along all planes that cut perpendicularly to the opening surface. It is characterized by exhibiting an arcuate surface, the ratio of the short axis to the long axis of the opening surface being 2.5 or less, and the depth thereof being approximately the same as or slightly larger than the short axis.
A die for single-stage molding of PTP pockets.