GB2051739A - Lubricant sheet for a tape cassette - Google Patents
Lubricant sheet for a tape cassette Download PDFInfo
- Publication number
- GB2051739A GB2051739A GB8014631A GB8014631A GB2051739A GB 2051739 A GB2051739 A GB 2051739A GB 8014631 A GB8014631 A GB 8014631A GB 8014631 A GB8014631 A GB 8014631A GB 2051739 A GB2051739 A GB 2051739A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sheet
- tape
- lubricant sheet
- lubricant
- base
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000314 lubricant Substances 0.000 title claims abstract description 31
- 239000004447 silicone coating Substances 0.000 claims abstract description 12
- -1 polyethylene Polymers 0.000 claims description 16
- 239000004698 Polyethylene Substances 0.000 claims description 7
- 229920000573 polyethylene Polymers 0.000 claims description 7
- 229920000298 Cellophane Polymers 0.000 claims description 3
- 239000004743 Polypropylene Substances 0.000 claims description 3
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 3
- 229920000515 polycarbonate Polymers 0.000 claims description 3
- 239000004417 polycarbonate Substances 0.000 claims description 3
- 229920001155 polypropylene Polymers 0.000 claims description 3
- KKEYFWRCBNTPAC-UHFFFAOYSA-L terephthalate(2-) Chemical compound [O-]C(=O)C1=CC=C(C([O-])=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-L 0.000 claims description 3
- 239000000463 material Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- 239000004809 Teflon Substances 0.000 description 3
- 229920006362 Teflon® Polymers 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920000139 polyethylene terephthalate Polymers 0.000 description 3
- 239000005020 polyethylene terephthalate Substances 0.000 description 3
- 229920001296 polysiloxane Polymers 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 238000006748 scratching Methods 0.000 description 2
- 230000002393 scratching effect Effects 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 235000019439 ethyl acetate Nutrition 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
- G11B23/02—Containers; Storing means both adapted to cooperate with the recording or reproducing means
- G11B23/04—Magazines; Cassettes for webs or filaments
- G11B23/08—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends
- G11B23/087—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends using two different reels or cores
- G11B23/08707—Details
- G11B23/08757—Guiding means
- G11B23/08764—Liner sheets
Landscapes
- Magnetic Record Carriers (AREA)
- Paints Or Removers (AREA)
Abstract
A lubricant sheet for a magnetic tape cassette, having a release type silicone coating 2 applied to at least one side of a transparent base 1. This lubricant sheet lowers the coefficient of friction of a transparent base without sacrificing its transparency. <IMAGE>
Description
SPECIFICATION
Lubricant sheet
This invention relates to a lubricant sheet for use in a magnetic tape cassette.
A magnetic tape cassette consists of upper and lower half cases formed of plastics and fastened together, and a length of magnetic tape wound on a pair of reels in the space within the complete case. As the tape passes from one reel to the other via an external tape head, both edges of the tape tend to travel in direct contact with the inner surfaces of the upper and lower half cases, producing such a high frictional resistance that the tape running becomes unsteady and instable. In order to avert this, it has been customary to insert pieces of lubricant sheet between the tape reels and the inner surfaces of the half cases. Thus, the lubricant sheet acts to improve the smoothness of tape running by decreasing the frictional resistance between the tape and the half cases, and also serves to prevent troubles such as objectionable loosening of the tape and choking of its passageway.Ordinarily, a lubricant sheet is required to have a low coefficient of friction and sufficient resistance to heat and moisture to preclude its dimensional changes with temperature and humidity. Sheet materials so far adopted for this use have been polyethylene and the like into which graphite and Teflon or graphite alone is incorporated.
Recently, it has been proposed to make the upper and lower half cases of magnetic tape cassettes from transparent plastics so that the interior of the cassettes can be seen from the outside to permit the user easily to see how much part of the tape has been wound on or unwound from which reel and watch the running condition of the tape. In addition, the transparency gives a look refined in design to the containers. In order that the cassettes may be built transparently, it is necessary that the case is made transparent and additionally the lubricant sheet, to be interposed between the inner surfaces of the case and reels inside, should be transparent.
For the application as the transparent sheet material, polyethylene terephthalate and such like polyesters, polypropylene, polyethylene, polymethylene terephthalate, polycarbonate, cellophane, styrol and the like were taken into consideration. However, high coefficients of friction and very low resistances to wear and damage make them unsuitable for direct employment as lubricant sheet materials. Tape cassettes using lubricant sheets of such materials will not ensure stable travel of the tapes, and the white powder resulting from the abrasion of the contacting surfaces will lead to troubles. Also, the development of numerous scratches will mar the outward appearance and render the otherwise transparent tape cassettes unsaleable.
It is an object of the present invention to provide a transparent lubricant sheet which will obviate or mitigate the foregoing difficulties without sacrificing its own transparency.
According to the present invention there is provided a lubricant sheet for a magnetic tape cassette, the sheet having a release type silicone coating applied to at least one side of a transparent base.
An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:
Figure 1 is a sectional view of a lubricant sheet;
Figure 2 is a graph showing the relation between the thickness of coated layer and the coefficient of friction; and
Figures 3(a) and 3bob) illustrate the surface conditions, respectively, of a silicone-coated sheet of the invention and an uncoated sheet each after 200 passes of the tape, recorded by a surface roughness tester.
Referring to Figure 1 of the drawings, a lubricant sheet comprises a transparent base 1 and a clear, release type silicone coating 2 applied to at least one side of the base. The sheet, thus made transparent as a whole, suits best, for incorporation into a transparent cassette. In use, it will not be damaged by the passage of the tape and will have long life.
Each face of the lubricant sheet within a cassette is in contact with the inner surface of the case on one side and with tape reels on the other. In order to lower the frictional resistance of the lubricant tape to the magnetic tape travelling while the cassette is in use, it is important that the silicone coating should be on the side of the sheet that faces the reels. Giving the silicone coating also on the opposite side contacting the inner surface of the case provides on advantage because it provides for protection to the base which is susceptible to damage.
A remarkable feature of the lubricant sheet according to the invention is that its coefficient of friction can be freely altered as desired by merely changing the thickness of the coated layer. Figure 2 is a graph showing the results of tests conducted to clarify the relation between the thickness of a film as coated layer and the coefficient of friction. The tests were performed by affixing films of silicone coating, the same in composition as that being taught by this invention but varied in film thickness, to the inclined surface of a tilted table whose angle of inclination is changeable as desired, placing reeled magnetic tapes on the films, gradually increasing the inclination angle H, and recording the angle Oat which each magnetic tape began to slide downward.It can be seen from the graph that the thicker the coated layer the smaller the tan 3, or the lower the coefficient of friction will be. In case of the conventional graphite-Teflon-containing sheet, the mixing ratio of graphite and Teflon composing the sheet, or the original material composition itself, must be changed if the coefficient of friction is to be altered. With the lubricant sheet of the invention, by contrast, the end is attained by simply controlling the thickness of the coated layer. This is highly advantageous from the industrial standpoint, because the requirements for changes in coefficient of friction according to the designs, materials, etc. of various magnetic tapes can be met with extreme ease.
Further, in this connection, it is possible, when coating the both sides of the base with the release type silicone, to provide coated layers different in thickness and hence in coefficient of friction. Upon the improvement in running quality of a magnetic tape, not only the condition of friction between the tape and the lubricant sheet but also the coefficient of friction between the sheet and the inner surface of the case will have delicate influences. Generally, the coating on the side of the sheet that contacts the tape is made thicker than on the opposite side that contacts the inner surface of the case, the thickness ratio being so chosen as to make the balance of the coefficients of friction between the two sides optimum for the particular magnetic tape cassette.It is of great significance that this optimization is accomplished through mere adjustment of the thickness of coated layers.
As already stated, the release type silicone coating on the base lowers the coefficient of friction. This not only helps the tape to run in a smooth and stabilized way but also reduces the possibility of the base being damaged and thereby enables the tape to stand a large number of usages. Figures 3(a) and (b) are graphs representing the scratches made on the tape side of a lubricant sheet consisting of a base of polyethylene terephthalate and a silicone coating applied to the base and the scratches made on the same side of an uncoated lubricant sheet, both sheets being fitted in place within cassettes and examined each after 200 passes of the tape, the results being recorded by a surface roughness tester. It will be appreciated that the uncoated sheet is given circumferential scratches by the running tape, whereas the sheet of the invention remains almost flawless.Next, the same lubricant sheets were tested for endurance on repeated passes, and the results given below again clearly indicate the superiority of the lubricant sheet of the invention to the ordinary one.
After 200
passes of tape
Sheet of polyethylene 16 out of 20
terephthalate with reeled tapes
silicone coating passed the test
Sheet of polyethylene 8 out of 20
terephthalate alone reeled tapes
passed the test
In brief, the lubricant sheet according to this invention is of a great industrial value in that it offers the following advantages: (1) As it lowers the coefficient of friction of a transparent base without sacrificing its transparency, the sheet can be suitably used with a transparent cassette and can smoothen the passage of the tape.
(2) Because the coefficient of friction can be modified as desired by merely changing the thickness of the coated layer, the sheet permits optimization of the tape passage with ease.
(3) With the ability of minimizing the wear and precluding scratching during use, the sheet has a greatly extended life.
(4) The sheet improves the running durability or service life of the tape.
The method of manufacturing the lubricant sheet according to the invention is as follows. For example, a silicone coating composition, consisting of 0.5 - 20% of release-type silicone, marketed by Shin-Etsu
Chemical Co. underthetradedesignation "condensation type KS-719" or "addition type KS-774", 0.5 - 5% of "addition type C-PL-4" as a curing catalyst, and 40 - 50% each of toluene and acetic ester, is applied in a suitable mannerta a base of polyethylene terephthalate, polypropylene, polyethylene, polycarbonate, polymethylene terephthalate, cellophane, or styrol, and the coating is cured at 600 - 800C for 24 - 48 hours. A sheet is then made in a desirable way. When lubricant sheets thus obtained were actually used in magnetic tape cassettes and tested with 200 passes of the tapes, the test sheets invariably gave satisfactory results in the running tape stability, sheet scratching, and durability against tape running.
Claims (5)
1. A lubricant sheet for a magnetic tape cassette, the sheet having a release type silicone coating applied to at least one side of a transparent base.
2. A lubricant sheet according to claim 1,wherein said base is selected from the group consisting of polyethylene, terephthalate, polypropylene, polyethylene, polymethylene terephthalate, polycarbonate, cellophane, and styrol.
3. A lubricant sheet according to claim 1, wherein said release type silicone coating is applied to the both sides of said base to form coats different in thickness.
4, A lubricant sheet substantially as hereinbefore described with reference to the accompanying drawings.
5. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5886679U JPS55160565U (en) | 1979-05-04 | 1979-05-04 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2051739A true GB2051739A (en) | 1981-01-21 |
| GB2051739B GB2051739B (en) | 1983-08-17 |
Family
ID=13096642
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8014631A Expired GB2051739B (en) | 1979-05-04 | 1980-05-02 | Lubricant sheet for a tape cassette |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS55160565U (en) |
| DE (1) | DE3017028A1 (en) |
| GB (1) | GB2051739B (en) |
| NL (1) | NL8002597A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55160576U (en) * | 1979-05-07 | 1980-11-18 |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE7411992U (en) * | 1974-07-18 | Kalle Ag | Washer for magnetic tape cassettes | |
| FR1577537A (en) * | 1967-06-30 | 1969-08-08 | ||
| DE1803575A1 (en) * | 1968-10-17 | 1970-05-27 | Agfa Gevaert Ag | Slide foil for sound tape cassette |
| JPS528128Y2 (en) * | 1972-04-18 | 1977-02-21 | ||
| JPS537115Y2 (en) * | 1973-05-22 | 1978-02-22 | ||
| JPS5536034B2 (en) * | 1973-06-18 | 1980-09-18 |
-
1979
- 1979-05-04 JP JP5886679U patent/JPS55160565U/ja active Pending
-
1980
- 1980-05-02 DE DE19803017028 patent/DE3017028A1/en active Granted
- 1980-05-02 GB GB8014631A patent/GB2051739B/en not_active Expired
- 1980-05-06 NL NL8002597A patent/NL8002597A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| DE3017028C2 (en) | 1989-03-02 |
| DE3017028A1 (en) | 1980-11-20 |
| NL8002597A (en) | 1980-11-06 |
| GB2051739B (en) | 1983-08-17 |
| JPS55160565U (en) | 1980-11-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930502 |