JPH0521755Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic tape cassette, and more particularly to a magnetic tape cassette having a cassette body made by transfer molding.

[Prior Art] A magnetic tape cassette is constructed by holding a winding hub on which a magnetic tape is wound inside a cassette body. This cassette body is usually made by injection molding of plastic material, etc. After this molding, paper or the like with a predetermined design is pasted on the outer surface of the body for the purpose of obtaining a design effect. A predetermined design can be printed directly.

However, this method requires a process of injection molding the body and a process of pasting paper, etc. on the outer surface of the body or a printing process, so it is difficult to print a predetermined design on the outer surface of the body at the same time as injection molding. A method called transfer molding was devised to do this. This transfer molding will be briefly explained below with reference to FIG. 4. Injection molding is performed using two molds 1 and 2, and when both molds 1 and 2 are put together, the shape of the cassette half formed by the recesses 3 and 4 of both molds 1 and 2 is formed. This is done by injecting a molten material, such as a plastic material, into the corresponding space through the injection hole 1b. When performing transfer molding, a transfer film 5 provided with an ink layer having a predetermined design is placed between the two molds 1 and 2 with the molds 1 and 2 separated, and the transfer film 5 is Place both molds 1 and 2 together by sandwiching them.
After that, a predetermined amount of molten material is injected from the gate 1a, and the transfer film 5 is pressed against the recess 4 of the mold 2, so that the space inside the mold formed by the recesses 3 and 4 is filled with the molten material. let At this time, the transfer film 5 is made by laminating a release layer 7, an ink layer 8, and an adhesive layer 9 in this order on a base film 6, for example, as shown in FIG. When contacted by the injected molten material, the adhesive layer 9 bonds the ink layer 8 to the injected material, ie, the surface of the cassette, and the release layer 7 allows the base film 6 to be easily peeled off from the cassette surface. Therefore, if the material filled in the mold space cools and hardens and then takes out the body and peels off the base film 6, the ink layer 8 on the transfer film 5 will be transferred to the surface of the body. left behind.

In this way, when an ink layer is transferred to the surface of the cassette body, this ink layer is exposed to the outside on the cassette surface, and the film strength of the ink layer formed by this transfer molding is not very strong, so it may be The ink layer may be rubbed or peeled off.

For this reason, the present applicant conducted injection molding similar to the above transfer molding using a protective film from which the release layer 7 of the transfer film 5 used in the above transfer molding was removed, and applied this protective film to the surface of the cassette body. We proposed a cassette body that is integrally joined to form a protective film layer. In this way, since the ink layer is located on the inner surface of the protective film layer and covered by the base film forming the protective film layer, the problem of the ink layer peeling off during use of the cassette will not occur. Furthermore, if this protective film layer covers the ridge of the cassette body, even if the injection molded material has low impact strength and is easily damaged, the protective film layer that covers it from the outside increases the impact strength. This also reduces the problem of damage to the cassette body.

[Problem that the invention attempts to solve]

However, transfer films may wrinkle during injection molding, resulting in streak-like patterns on the ink layer, and especially when forming the above-mentioned protective film layer, streak-like irregularities may occur on the surface of the cassette body. There was a problem that occurred at the same time. This problem occurs because the injection hole 1b is located near the outer periphery of the cassette body, so the flow of the synthetic resin in one direction causes the film to elongate unbalanced.
It is particularly likely to occur near the boundaries where the surface of the cassette body is stepped and around the hub holes.

As a result, the cassette body has a problem of being inferior in appearance or, in severe cases, becoming a defective product. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magnetic tape cassette that does not cause wrinkles on the transfer film.

[Means for solving problems]

The object of the present invention is to provide a magnetic tape in which a pair of hubs wound with magnetic tape are rotatably built into the hollow interior of a cassette body formed by transfer molding in which at least the transfer layer of a transfer film is integrally bonded to the surface of the cassette body. This can be achieved by a magnetic tape cassette characterized in that injection holes for injecting molten synthetic resin into the injection mold are provided between the hub holes corresponding to the hubs and in the central region of the cassette body. can.

[Effect]

By providing the injection hole for injecting the synthetic resin constituting the cassette body into the mold in the central region of the cassette body, the injection pressure during resin injection is prevented from being biased against the transfer film, and Since the resin flows from the center of the cassette body toward the outer periphery, wrinkles in the transfer film can be extremely effectively prevented.

[Embodiment]

Hereinafter, preferred embodiments of the present invention illustrated in the drawings will be described.

FIG. 1 is a perspective view showing a magnetic tape cassette according to the present invention. A hub 13 is rotatably built in. Then, the upper half 10 and the lower half 11
are injection molded separately,
As shown in FIG. 2, which shows a cross section along the arrow - in FIG.
Base bodies 10a and 11a made of plastic injection material such as ABS resin, and base body 1
It consists of a protective film layer 12 that covers the surfaces of 0a and 11a. In addition, at this time, the transfer film 2
It is preferable that the protective film layer 12 formed by the protective film layer 12 be formed to cover at least the ridges 10b, 11b of each half 10, 11 from the viewpoint of strengthening the cassette body.

This protective film layer 12 has each half 10, 11
The protective film layer 12 is formed simultaneously with the injection molding, and the formation of the protective film layer 12 will be described below. This cassette body is made using two appropriately divided molds as in the past, but as shown in FIG. 4, for example, one half is molded in four molds at the same time. Then, the protective film layer 12 is formed on the surface of the cassette body by sandwiching the transfer film 20 between the mold 1 and another mold (not shown) corresponding to the mold 1 and performing injection molding. The transfer film 20 is a belt-shaped one in which the protective film layer 12 is formed in a pattern corresponding to the mold.
It is intermittently sent downward in the figure (in the direction of arrow B) as appropriate. Further, during injection molding, it is held by, for example, plate-shaped holding means 21 so that appropriate tension is generated in the direction of arrow A. As shown in FIG. 3, this protective film layer 12 has an ink layer 12b on the inner surface of the base film 12a (the side in contact with the base bodies 10a, 11a), which has a design representing the external appearance of the magnetic tape cassette. and this protective film layer 12 as a base body 10a,
An adhesive layer 12c for bonding to the base film 11a is laminated in this order, and an antistatic layer 12d is provided on the outer surface of the base film 12a, if necessary. Furthermore, this base film 12
As the material a, for example, polymeric materials such as polyethylene, polyethylene terephthalate, polypropylene, triacetate cellulose, etc. can be used. Further, as the antistatic layer 12d, for example, the one disclosed in Japanese Utility Model Application No. 115519/1984 can be used.

The mold 1 is provided with injection holes 30 (gates) for injecting the molten resin constituting the base body into each recess 3, but the position of the injection holes 30 is different from that of conventional molds. and are provided between the hub holes 14, respectively. In detail, this injection hole 30, as shown enlarged in FIG.
For example, two recesses are provided in one recess 3, and their positions are on the line X connecting the centers of the hub holes 14,
Moreover, they are provided symmetrically with respect to the center line Y between the hub holes.

Therefore, the resin that has entered the recess 3 from the injection hole 30 flows outward from the central region of the cassette body, so that the resin flows outward from the approximately central portion of the cassette body with respect to the transfer film 20. As a result, the transfer film 20 is stretched almost evenly, and the transfer film 20 is prevented from being stretched or deformed unevenly due to resin outflow pressure. Therefore, the generation of wrinkles on the transfer film 20 is prevented. In particular, since the transfer film 20 is stretched in the A direction as described above, in the past, wrinkles were likely to occur due to resin flow only in a biased direction that intersects the A direction at an approximately appropriate angle, but in the present embodiment. In this case, the occurrence of wrinkles can be effectively prevented by the resin flow from the center to the outer periphery. That is, when resin is injected from one side of the cassette body as in the past, even if tension is applied in the A direction, the transfer film elongates from the injection direction, and the elongation accumulates on the side opposite to the injection, causing wrinkles. However, by injecting the resin in the central region of the cassette body, the unevenness and accumulation of film elongation deformation is avoided, and the film elongation appropriately responds to changes in the unevenness of the cassette body. Therefore, wrinkles can be prevented and the transfer film can be formed satisfactorily.

In the embodiment described above, two injection holes 30 are provided, but the present invention is not limited to this. For example, one injection hole 30 may be provided at the intersection of the line X and the center line Y. Alternatively, a plurality of pairs may be provided near the line X and symmetrically with respect to the center line Y.

[Effect of idea]

As described above, according to the present invention, in injection molding of a cassette body in which a transfer film is disposed in the mold and the transfer film is integrally bonded to the surface of the cassette body, the transfer film is placed inside the mold. Since the resin injection hole is provided in the center area of the cassette body between the hub holes, the pressure on the transfer film due to the resin injection pressure is transmitted almost evenly from the center of the body to the outside of the body, which reduces the elongation of the transfer film. This prevents the transfer film from shifting to one side, and allows the elongation of the transfer film to appropriately correspond to the unevenness of the cassette body. Therefore, it is possible to provide a magnetic tape cassette in which wrinkles are prevented from forming on the transfer film, and the magnetic tape cassette is free from unexpected patterns, irregularities, and deviations in patterns caused by wrinkles on the surface of the body.

[Brief explanation of drawings]

1 is a perspective view showing an embodiment of the magnetic tape cassette according to the present invention, FIG. 2 is a sectional view taken along the arrow - in FIG. 1, and FIG. 3 is a cassette of the magnetic tape cassette shown in FIG. 1. 4 is a sectional view of the transfer film bonded to the body surface, FIG. 4 is a plan view showing one aspect of the mold for injection molding the cassette half of the magnetic tape cassette shown in FIG. 1, and FIG. 5 is the same as FIG. 4. FIG. 6 is a cross-sectional view showing an injection mold used for transfer molding of a cassette half of a conventional magnetic tape cassette, and FIG. 7 is a transfer film related to the transfer molding shown in FIG. 6. FIG. 1, 2... Mold, 16, 30... Injection hole, 3,
4... Concavity, 5, 20... Transfer film, 10...
...upper half, 10a, 11a...base body,
11...lower half, 12a...base film,
12b... Ink layer, 12c... Adhesive layer, 12
d... Antistatic layer, 21... Holding means.

Claims (1)

[Claims for Utility Model Registration] 1. A pair of hubs wound with magnetic tape are rotatably built into the hollow interior of a cassette body formed by transfer molding in which at least the transfer layer of a transfer film is integrally bonded to the surface of the cassette body. 1. A magnetic tape cassette according to the invention, wherein an injection hole for injecting molten synthetic resin into the injection mold is provided between the hub holes corresponding to the hubs and in the central region of the cassette body. 2. The magnetic tape cassette according to claim 1, wherein the injection hole is located at the center of a line connecting the centers of the hub holes. 3. The magnetic tape cassette according to claim 1, wherein the injection holes are provided in one or more pairs on a line connecting the centers of the hub holes and symmetrically from the center between the hub holes. .