JPH0584593B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a magnetic tape cassette, and more particularly to a magnetic tape cassette having a cassette body on which a protective film layer made of a polymeric material or the like is formed on the surface. This invention relates to a method of manufacturing a tape cassette.

(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. 6. 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 a corresponding space from a gate 1a through an injection hole 1b. When performing transfer molding, both molds 1 and 2 are
A transfer film 5 provided with an ink layer having a predetermined design is placed between the molds 1 and 2 with the molds 1 and 2 separated, and the molds 1 and 2 are placed between the molds 1 and 2 with the transfer film 5 in between.
Match 2. After that, a predetermined amount of molten material is injected from the gate 1a, and the transfer film 5 is transferred to the mold 2.
The space inside the mold formed by the recesses 3 and 4 is filled with the molten material by pressing it against the recess 4 of the mold. 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, as shown in FIG. Upon contact with the molten material, the adhesive layer 9 bonds the ink layer 8 to the injection material or 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, after this,
When the material filled in the mold space cools and solidifies, the body is taken out and the base film 6 is peeled off, leaving the ink layer 8 on the transfer film 5 in a transferred state on the surface of the body.

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.

Furthermore, as mentioned above, if the cassette body is made by injection molding of plastic material, etc., it is easy to manufacture and mass-produce. Therefore, there is a problem that the impact strength is relatively low, and the body is easily damaged if the magnetic tape cassette is accidentally dropped on the floor.

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.

(Problems to be Solved by the Invention) As described above, in order to bond and form a protective film layer on the surface of a cassette body at the same time as injection molding, the transfer film 5 is placed between the molds 1 and 2 shown in FIG. Instead, a protective film will be placed and injection molding will be performed. This protective film is made so that continuous injection molding can be performed by feeding the strip film one frame at a time each time injection molding is performed. It is necessary to punch and cut the protective film to size and place the punched protective film in a mold to form a protective film layer on the surface of the cassette body. If this punching and cutting is performed after injection molding, punching after injection molding is difficult and requires a separate punching process, which is undesirable as it reduces production efficiency and increases production cost. Another method is to provide a cutting section in the mold and use this cutting section to punch out the protective film into a predetermined size when the molds are put together, but this method causes a large amount of wear on the cutting section of the mold. , there is a problem that the life of the mold is shortened.

(Means for Solving the Problems) For these reasons, the present invention provides the above-mentioned production method when manufacturing a protective film layer when bonding and forming a protective film layer on the surface of a cassette body in a magnetic tape cassette. The purpose is to obtain a manufacturing method that does not reduce efficiency or increase production costs, and does not significantly reduce the life of the mold, and the following method is used as a means for this purpose.

In this manufacturing method, first, a strip film consisting of a plurality of protective film layers is punched out into a desired shape leaving a connecting portion and connected in a strip shape through the connecting portion, and is placed in two molds for injection molding. a step of placing the two molds together, positioning one protective film layer of the strip film in the mold, and sandwiching the connecting portion with the mold; After this, injection material such as plastic material is injected and supplied into the mold.
It consists of a step of integrally bonding a protective film layer to the surface of the cassette body.

(Embodiments) Preferred embodiments of the present invention will be described below with reference to the drawings.

Before explaining the manufacturing method according to the present invention,
First, a magnetic tape cassette having a protective film layer manufactured by this method will be explained. This magnetic tape cassette includes a cassette body made up of an upper half 11 and a lower half 15, a pair of hub parts 11b of this cassette body,
A pair of winding hubs 21, 21 rotatably held in the hub portions 15b, 15b of the lower half 15 (11b, 15b, 15b, not shown), and a magnetic tape 22 wound around the winding hubs. Consisting of
The upper half 11 and the lower half 15 are injection molded separately, and are indicated by the arrows -- in FIG.
As shown in FIG. 4, which shows a cross-section along It consists of. At this time, it is desirable that the protective film layers 12, 16 be formed to at least cover the ridges 11a, 15a of the respective halves 11, 115 from the viewpoint of strengthening the cassette body.

This protective film layer 12, 16 is
1, 15, the protective film layer 12, 15 is bonded to the surface of each half 11, 15 at the same time as this injection molding, and then this protective film layer 12, 1
A manufacturing method for forming 6 will be explained based on FIG. Although this cassette body is manufactured using the molds 31 and 32 shown in FIG. 1, injection molding of the upper half 11 will be described below as an example. First, the mold 31,
32 are separated and the plurality of protective film layers 12 are removed during this time.
A strip-shaped film made by continuously connecting two is placed. As shown in FIG. 5 in cross section, this strip-shaped film has an ink layer 12b and an ink layer 12b on the inner surface of the base film 12a (the side that contacts the base body 13), which has a design representing the external appearance of a magnetic tape cassette. This protective film layer 12
An adhesive layer 12c for bonding the base body 13 to the base body 13 is laminated in this order. Note that the base film 12a is made of the following materials:
Polymeric materials such as polyethylene, polyethylene terephthalate, polypropylene, and cellulose triacetate are often used.

Furthermore, as shown in FIG. 1, this protective film layer 12 is made of a long strip-shaped film with a contour punching 1 for forming the contour of a joint portion 12f of a predetermined size.
2d and a dividing punch 12e extending laterally to divide each protective film layer, and a plurality of joints 12f forming a plurality of protective film layers are continuously connected.
In this case, the contour punchings 12d are connected at the upper and lower central portions, and the division punchings 12d are connected from the center.
A connecting portion 12g is formed by the portion connected to e. That is, the joint portions 12f, which are joined to the surface of the cassette body during injection molding to form the protective film 12, are continuously connected in a band shape by the connecting portions 12g.

The inner surface of such a strip film is gate 1.
The joining part 12f is positioned in the space formed by the recesses 33, 34 of the two molds 31, 32 (the recess 33 is not shown) so as to face the mold 1 having a The connecting portion 12g is held between the molds 31 and 32, and then the injection material is injected from the gate 1a through the injection hole 1b into the recesses 33 and 34.
Inject and supply into the space formed by. In addition, when the connecting part 12g is held, the left and right sides of the connecting part 12g are cut along the broken line in the figure, and the connecting part 12g is cut off along the broken line in the figure.
The connecting portion 12f is separated from the outer frame, and in this separated state, the connecting portion 12g is connected to the mold 31,
32. In this way, the material is injected into the space formed by both the recesses 33 and 34 while the joint portion 12g is held between the molds 31 and 32 and the joint portion 12f is pressed against the recess 34 of the mold 32. is full. At this time, this injection material comes into contact with the adhesive 12c of the protective film layer 12, and the base film 12a and ink layer 12b forming the protective film layer 12 are brought into contact with the surface of the base body 13 where the injection material has cooled and hardened. is joined to.

FIG. 2 shows the upper half injection molded in this way removed from the molds 31 and 32, and as can be seen from this figure, the joint 12f is joined to the outer surface of the upper half 15. A protective film layer 12 is formed thereon, and connecting portions 12g, 12g connected to this joint portion 12f extend vertically from the upper half 15. The connecting portions 12g, 12g may be cut or may be bent and glued into the upper half 15.

In addition, during injection molding, the joint portion 12f is formed into the recessed portion 34.
Since the connecting portion 12g held between the molds 31 and 32 is pressed by the metal molds 31 and 32, wrinkles often occur. It is possible to prevent wrinkles caused in the connecting portion 12g by the connecting portion 12e from affecting the next joint portion 12f.

When the cassette body is manufactured in this way, a protective film layer 1 is applied to the surface by injection molding.
A cassette half having a protective film layer 1 can be easily and continuously made.
If an ink layer representing the exterior design of the cassette is previously provided on the inner surface of the cassette, it becomes possible to simultaneously display the design on the surface of the cassette by injection molding. However, in this case, the base film 12a must be transparent or semitransparent, and it goes without saying that this ink layer may or may not be provided.

(Effects of the Invention) As explained above, according to the present invention, when the cassette body of a magnetic tape cassette is manufactured by injection molding of plastic material, etc., it is punched out into a desired shape leaving the connecting portion, and the connecting portion is A band-shaped film consisting of a plurality of protective film layers connected in a band-like manner through the cassette body is placed in a mold, and while the connecting portion is held between the molds, the injection material is injected into the mold space to form the protective film layer on the surface of the cassette body. Since they are integrally joined, it is easy to manufacture a cassette body having a protective film layer on the surface.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a mold used in the manufacturing method of the present invention, FIG. 2 is a perspective view showing an upper half injection molded by the above method, and FIG. 3 is a perspective view showing a protective film layer on the surface by the above manufacturing method. FIG. 4 is a cross-sectional view of the magnetic tape cassette taken along the arrow - in FIG. 3; FIG. 5 is a perspective view showing the magnetic tape cassette formed; FIG. 6 is a sectional view showing an injection mold used for transfer molding of a conventional magnetic tape cassette half, and FIG. 7 is a sectional view showing a transfer molding film for transfer molding. be. 1, 2, 31, 32...Mold, 5...Transfer film, 11...Upper half, 15...Lower half, 1
1a, 15a1...edge portion, 12, 16...protective film layer, 12f...joint portion, 12g...connection portion, 13, 17...base body.

Claims (1)

[Scope of Claims] 1. A magnetic tape cassette comprising a magnetic tape, a pair of winding hubs, and a cassette body rotatably holding the winding hub in a state in which the magnetic tape is wound therein, the cassette body comprising: a magnetic tape; The body is made of a plastic material or the like by injection molding, and the surface of the cassette body is provided with a protective film layer that is placed in the injection mold and integrally bonded at the same time as the injection molding. In the method for manufacturing magnetic tape cassettes, between the two molds used for the injection molding,
A strip film consisting of a plurality of protective film layers connected in a strip shape through the coupling portions is punched out into a desired shape leaving a connecting portion, and then the two molds are combined to form one of the strip films. positioning two protective film layers in the mold and sandwiching the connecting portion with the mold;
A method for producing a protective film layer for a magnetic tape cassette, characterized in that the protective film layer is integrally bonded to the surface of the cassette body by injecting and supplying an injection material such as a plastic material into the mold.