JPH0519907Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention relates to a magnetic tape cassette, and more particularly to a magnetic tape cassette with an improved tape guide for guiding tape running. (Prior Art) As is well known, in magnetic tape cassettes used for audio and video, the magnetic tape is wound around a pair of tape winding bodies (reels and hubs) and stored in a cassette case. A tape guide is provided near the opening of the tape guide for guiding the running of the tape and regulating its running route when the tape is running during recording and reproduction.
Since the above-mentioned tape guide is in sliding contact with the magnetic tape, it is required to have so-called friction resistance, abrasion resistance, etc., hardness, non-static property, and smooth surface property. In particular, in video tape cassettes, high-density recording and playback is performed, so the above requirements are even higher.
Conventionally, it is common to use a metallic tape guide. However, metal tape guides have had problems in terms of cost, not only the material cost but also the need for many processing steps. For this reason, various studies have been made to use synthetic resin for tape guides in order to reduce costs, but since synthetic resins basically have poor heat dissipation properties, magnetic tapes based on polyester films, etc. It has not been realized because it has poor friction and wear resistance against sliding over many years, and when plating is applied, there are problems such as deformation due to heat and high costs due to secondary processing. That was the current situation. (Purpose of the invention) The present invention was devised in view of the above-mentioned problems, and provides a magnetic tape cassette equipped with a tape guide that can guarantee stable tape running over a long period of time and has excellent productivity. The purpose is to provide (Structure of the invention) The above-mentioned object of the invention is to provide a magnetic tape in which a magnetic tape wound around a pair of tape wrapping bodies is built into a case, and a tape guide is provided in contact with the magnetic tape to guide the tape running. In the cassette, the tape guide is achieved by a magnetic tape cassette characterized in that the core is made of synthetic resin and the surface is provided with a surface hardening layer of a polyfunctional acrylate curing agent hardened by ultraviolet rays or electron beam irradiation. be done. (Embodiments) Hereinafter, preferred embodiments of the present invention illustrated in the drawings will be described in detail. FIG. 1 is an exploded perspective view of the front portion of a videotape cassette that is an embodiment of the present invention;
The figure is an enlarged vertical sectional view of the main part. A video tape cassette 1 shown in FIG. 1 is provided with tape guides 4, 5, and 6 near both left and right sides of an opening 3 at the front of the cassette for guiding the tape in contact with the front or back surface of the magnetic tape T.
A relatively thick tape guide 4 provided closest to the front and a thinner tape guide 5 provided close to the reel 8a on the tape supply side are formed integrally with the lower half case 2. Further, the cylindrical tape guide 6 (guide roller) rotatably provided close to the reel 8b on the tape winding side is made of a synthetic resin mainly composed of plastic resin such as POM, for example. The above tape guide 4 is as shown in FIG.
The core part 10 is a cylindrical part formed integrally with the lower half case 2 by injection molding, and is naturally made of the same material as the lower half case 2, for example, a synthetic resin such as ABC. For example, a polyfunctional acrylate hardening agent as shown in Table 1 is coated, and the hardening agent forms a surface hardening layer 11 that is hardened by irradiation with ultraviolet rays or electron beams. The polyfunctional acrylate-based ultraviolet curing method will be briefly described below. As shown in Table 1, the polyfunctional acrylate surface hardening agent is composed of monomers and oligomers having two or more acryloyloxy or methacryloyloxy groups at the terminal or side chain of the molecule. Although there are many types of these compounds, surface curing agents composed of polyfunctional acrylates have the characteristic of being able to freely change the performance of the cured film. Furthermore, since it is essentially the same organic material as the plastic used as the base material, it has good conformability to the base material, and has good adhesion and flexibility. The reaction mechanism is as shown in the following formula: [Initiation] Ihν −−−−→ hνI ^* , I ^* →R・R・+M→RM・ [Growth] RM・+M→RM ₂・ Here, I: Photopolymerization Initiator M: Monomer I ^* : Excited photopolymerization initiator R: Active radicals generated from I Although there is a difference whether the initiating radical is generated by heat or light, it is radical polymerization. Therefore, the photopolymerization initiator does not decompose unless it is irradiated with high-energy light, and the polyfunctional acrylate surface hardening agent is stable against heat and has a considerably longer life than the organosilane surface hardening agent. Irradiation with ultraviolet rays does not require any particular atmospheric conditions, and can be carried out under relatively simple conditions, for example, at room temperature for about 2 to 30 seconds. Further, the working process is performed as shown in the flowchart shown in FIG. 3, for example. At the upper end of the tape guide 4, for example, a recess 12 is provided for fitting with an upper half case (not shown).
is provided. Similarly to the tape guide 4, the body of the tape guide 5 is coated with a polyfunctional acrylate curing agent, and is also treated with ultraviolet irradiation. As described above, since the tape guides 4 and 5 are provided with the hardened surface layer 11, they have excellent friction/abrasion resistance, heat resistance, and surface properties against sliding of the magnetic tape T. Further, the core portions 10 of both guides 4 and 5 are integrally formed with the lower half case 2,
The manufacturing process is extremely simplified. The surface hardening layer 11 may also be provided on the rotatably provided tape guide 6, but in this case, it is not so necessary since there is less friction with the magnetic tape T than with the tape guides 4 and 5. .

[Table] Furthermore, although the above embodiments have been described with respect to video tape cassettes, it goes without saying that the present invention can also be applied to magnetic tape cassettes used for audio and the like. (Effects of the invention) As explained above, the tape guide according to the invention is constructed so that the synthetic resin core is covered with a polyfunctional acrylate surface hardening layer.
The friction resistance, abrasion resistance, thermal conductivity, non-static properties, surface properties, etc. are comparable to those of conventional metal tape guides, and the productivity is extremely excellent. Therefore, according to the present invention, it is possible to provide a magnetic tape cassette equipped with a tape guide that guarantees good tape running over a long period of time and has excellent productivity.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of the front portion of a videotape cassette that is an embodiment of the present invention, Fig. 2 is an enlarged vertical sectional view of the main part of Fig. 1, and Fig. 3 is a flowchart of the ultraviolet curing method. It is. DESCRIPTION OF SYMBOLS 1... Video tape cassette, 2... Lower half case, 3... Opening, 4, 5, 6... Tape guide, 8a, 8b... Tape reel, 10... Core, 11... Surface hardening layer , 12... recess.

Claims (1)

[Scope of utility model registration request] In a magnetic tape cassette, a magnetic tape wound around a pair of tape winding bodies is housed in a case and is equipped with a tape guide that guides the tape running in contact with the magnetic tape, the tape guide having a core made of synthetic material. A magnetic tape cassette made of resin, integrally formed with a cassette half, and provided with a surface hardening layer of a polyfunctional acrylate curing agent hardened by ultraviolet rays or electron beam irradiation.