JPS6223365B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a leader tape used by being attached to the end of a magnetic tape, and particularly to a leader tape with improved abrasion resistance and transparency. 2. Description of the Related Art Conventionally, a method for optically detecting the end of a magnetic tape in a video tape recorder is known. This method consists of a light source and a phototransistor, and the end of the magnetic tape is detected by passing a transparent leader tape attached to the end of the magnetic tape over a line connecting the light source and the phototransistor. . As leader tapes used for this purpose, transparent polymer films such as polyethylene terephthalate film, cellulose acetate film, and polyvinyl chloride film, which have not been subjected to any special treatment, are usually used. Although these materials have excellent transparency, they have the disadvantage of high electrical resistance, and as a result, they tend to be charged with static electricity. Dirt and dust picked up by static electricity will eventually adhere to the magnetic surface or magnetic head, resulting in dropouts and decreased output. This was the cause of such problems. On the other hand, methods have been proposed in which a layer containing an antistatic agent or a pigment is provided on a polymer film base in order to prevent charging of the leader tape, but these methods cannot exhibit sufficient performance.
That is, the antistatic agent is susceptible to the influence of humidity, and if a large amount of the antistatic agent is used, the conductivity is improved, but there is a drawback that adhesion tends to occur. also,
Since white pigments have a small antistatic effect, there is a contradiction in that if the amount added is increased until a sufficient antistatic effect is achieved, light scattering will increase and transparency will decrease. Furthermore, leader tapes made of untreated polymer films or coated with antistatic agents do not have sufficient abrasion resistance. When loading a magnetic tape or detecting the end during recording and playback, the leader tape is in contact with the rotating magnetic head, so if the leader tape does not have wear resistance, the tape surface will be scraped off, causing the head to become clogged. becomes. By the way, if a metal oxide layer is provided as an antistatic layer on a flexible support base, a leader tape can be obtained which has excellent transparency and antistatic properties and is not affected by humidity. The leader tape provided with such a metal oxide layer is (i) a flexible support having a surface roughness of 0.15 μm or more that is surface-activated, and then a transparent conductive metal oxide layer is provided thereon ( (see JP-A No. 53-34505), (ii) a transparent conductive metal oxide layer and a silicon oxide protective layer stacked on a non-magnetic flexible support (see JP-A-53-67408); ) have been proposed, all of which claim that durability can be improved by roughening the surface. However, although the degree of surface roughening needs to be 0.15 μm or more, particularly 0.25 μm or more, it has been thought that if the roughness is, for example, 1.8 μm or more, the light transmittance will decrease. As a result of intensive research into a method for increasing the adhesive strength by further increasing the degree of roughness without reducing light transmittance, the inventor found that by providing a silicon compound layer between the metal oxide layer and the rough surface, The inventors have discovered that the above object can be achieved and have arrived at the present invention. That is, the present invention provides (1) providing a silicon compound layer (A) on the rough surface of a transparent flexible support plate whose at least one side is roughened;
A leader tape further comprising a transparent conductive layer (B) made of a metal oxide laminated on the layer (A), wherein the rough surface has a roughness of 2 μm to 4 μm. It is. An organic polymer compound is preferably used as the material for the transparent flexible support plate in the present invention. In terms of transparency, flexibility, mechanical properties, etc., polyethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate, polycarbonate, polystyrene, cellulose triacetate,
Examples include cellulose diacetate, polyvinyl chloride, polypropylene, polyamide, and the like. These can be used as homopolymers or copolymers, alone or in blends. The thickness of the transparent flexible support plate is not particularly limited, but may be 5
~200 μm is preferred. Further, the support may be made of the above-mentioned materials containing pigments, brighteners, antistatic agents, plasticizers, and the like. The method for roughening the surface of the support is not particularly limited. For example, physical methods such as sandblasting or embossing with a rough-etched metal roll, chemical methods such as etching using corrosive alkaline aqueous solutions or amine solvents, and inorganic powders such as silica and alumina. A method of applying a resin layer containing . Particularly preferred is sandblasting, in which a high-hardness sand-like material such as silica sand is struck onto the surface of the support plate, for example, a polymer film, using a high-speed rotary blade, or a high-hardness sand-like material such as silica sand is blown into a stream of water. This is achieved by mixing and hitting the surface of the polymer film with a high-pressure pump to scrape off the surface of the support plate. In addition, the method of applying the inorganic powder-containing resin layer is such that the inorganic powder is mixed with 10 to 400 parts by weight, preferably 10 to 100 parts by weight, per 100 parts by weight of the resin, and the dispersed inorganic powder-containing resin is preferably 0.1 to 12 μm thick. This is particularly preferably achieved by coating to a thickness of 1 to 10 μm. As an inorganic powder, silica white [SiO ₂
nH ₂ O], alumina white [Al(OH) ₃ ], lead white [2PbCO ₃・Pb(OH) ₂ ], antimony white [Sb ₂ O ₃ ], silicon oxide [SiO ₂ ], aluminum oxide, zinc oxide, Zinc sulfide, tin oxide, zirconium oxide, titanium oxide, calcium carbonate, barium carbonate, barium sulfate, lead sulfate [ _2PbSO4・PbO],
Lead silicate [PbO・nSiO ₂ ], magnesium silicate [MgSiO ₂ ], talc [3MgO・4SiO ₂・H ₂ O], clay [Al ₂ O ₃・2SiO ₂・2H ₂ O], lithobon [ZnS+
BaSO ₄ ], etc. One or two of these
A mixture and dispersion of at least one species in a resin (binder) is used. Among these, inorganic powders containing silicon oxide and aluminum oxide as main components are preferred. The average particle diameter of the inorganic powder is preferably 0.01 to 10 μm. Resins (binders) include vinyl chloride/vinyl acetate copolymer, acrylic ester/styrene copolymer, cellulose resin, vinyl chloride/vinylidene chloride copolymer, polyamide resin, polyurethane resin, acrylic ester/acrylonitrile copolymer, etc. Thermoplastic resins such as polymers, acrylic ester resins, polyester resins, and vinyl acetate resins;
Epoxy resins include thermosetting resins such as melamine resins and phenol resins, and can be used alone or in a mixture of two or more as appropriate. These resins are dissolved in a suitable solvent, and the inorganic powder is further mixed and dispersed to prepare a coating liquid. Additives such as curing agents, thickeners, antioxidants, etc. may be added to the coating liquid as necessary. These coating liquids are applied by a conventionally known coating method and dried. The surface of the transparent flexible support plate can be roughened by various means as described above, but among the above methods, (1) physical method, (2) chemical method, and (3) coating method are preferred in this order. The degree of surface roughening is preferably 2 μm to 3.5 μm. An organic or inorganic silicon compound layer (A) is then applied to the roughened surface of the thus obtained transparent flexible support.
will be established. The organosilicon compound used in the present invention has the following general formulas (1) to (3). [However, R ₁ in the formula is the following two formulas [However, in the formula, R ₅ and R ₆ are each independently a hydrogen atom,
Alkyl groups having 1 to 4 carbon atoms, hydroxyalkyl groups, phenyl groups, allyl groups (-CH ₂ -CH
= _CH2 ) and carboxymethyl group ( _-CH2-
COOH). ] A group represented by

[Formula] -SH, -Cl,

【formula】

[Formula] and

[However, in the formula, R is an organic group such as methyl, ethyl, propyl, butyl, vinyl, phenyl, methacryloxy, methacryloxypropyl; X is a halogen atom, alkoxy group, t-butylperoxy group, or acyl group; m is 1 Integers from to 3 satisfy n+m=4. ]

Preferably, one or more compounds selected from the group consisting of compounds represented by the above and prepolymers obtained by hydrolyzing these compounds are used. Such organosilicon compounds can be used as a mixture with other organometallic compounds, such as organotitanium compounds, as long as they do not impede the effects of the present invention. It can also be used in combination with modifiers, plasticizers, various stabilizers, flame retardants, antioxidants, lubricants, antifoaming agents, and/or thickeners. This may be used as it is or after being dissolved in a solvent. Such solvents include methanol,
Examples include one or a mixture of two or more of ethanol, isopropanol, n-butanol, toluene, ethyl acetate, and the like. The thickness of the organosilicon compound layer (A) is not particularly limited, but is preferably in the range of 0.01 to 10 μm. In terms of wear resistance and optical properties, the thickness is particularly preferably 0.05 to 1 μm. If the thickness is less than 0.01 μm, it will be difficult to form a continuous film, making it impossible to achieve the intended purpose. On the other hand, if the thickness exceeds 10 μm, peeling or cracking may occur, and the flexibility of the support may be lost, which is not preferable. For coating the organosilicon compound, a coating method using known coating machines such as a doctor knife, bar coater, gravure roll coater, curtain coater, knife coater, etc. is used depending on the flexible support and the shape and properties of the organosilicon compound. , spray method, dipping method, etc. are used. After being applied, the organosilicon compound is dried and cured by heating, ion bombardment, or radiation such as ultraviolet rays, β rays, and γ rays. The inorganic silicon compound used in the present invention is represented by the general formula SiOx (O<x≦2), and includes Si, SiO,
It is one type of SiO ₂ or a mixture of two or more types. The thickness of the inorganic silicon compound layer used in the present invention is preferably 50 to 5000 Å, particularly preferably,
It is 100 to 3000 Å. If it is less than 50 Å, the mechanical strength of the inorganic silicon compound layer will be weak and the effects of the present invention cannot be expected. Further, if the thickness is 5000 Å or more, the inorganic silicon compound layer tends to crack or peel, which is not preferable. As a method for providing an inorganic silicon compound layer,
Examples of methods include sputtering method, vacuum evaporation method, and ion plating method. Various conventional methods are used for sputtering. Regarding targets, there are methods such as chemical sputtering of Si in an oxidizing atmosphere and high frequency sputtering of SiO ₂ . Various ordinary methods are used for vacuum evaporation and ion plating. The vapor deposition materials include Si,
One type or a mixture of two or more of SiO and SiO ₂ can be used. Various methods for providing the inorganic silicon compound layer can be selected depending on the heat resistance of the flexible support. The composition of the obtained inorganic silicon compound layer varies depending on the sputtering conditions, vacuum deposition conditions, ion plating conditions, etc. in the coating
As Si increases, the transparency of the film deteriorates. In particular, when transparency is required, it is desirable to select sputtering conditions, vacuum deposition conditions, ion plating conditions, etc. that will yield a film with low Si content. Furthermore, the transparency of the film can be improved by annealing it in air after forming the inorganic silicon compound layer. Among the organosilicon compounds and inorganic silicon compounds, it is preferable to use organosilicon compounds. Next, examples of the metal oxide used in the present invention include oxides of one or more metals selected from the group consisting of indium, tin, cadmium, zirconium, and titanium. These metal oxides are originally transparent electrical insulators, but if they contain trace amounts of impurities or are slightly oxygen deficient,
When it is an oxide of two or more metals, it becomes a semiconductor. The metal oxide constituting the transparent conductive film of the present invention must be a semiconductor. Preferred semiconductor metal oxides include, for example, tin-doped indium oxide [(In) ₂ =x(Sn)xO ₃ -y];
Antimony-doped tin oxide [(Sn) ₁ −m
(Sb) mO ₂ −n], cadmium tin oxide (Cd ₂ SnO ₄ ), and the like. In order to obtain sufficient conductivity, the thickness of these metal oxide films is preferably 10 Å or more, more preferably 30 Å or more. Further, in order to obtain a film with sufficiently high transparency, the thickness is preferably 5000 Å or less, more preferably 3000 Å or less. Methods for providing these semiconductor metal oxide films on layers made of silicon compounds include methods such as sputtering, vacuum evaporation, and ion plating. Various conventional methods can be used for sputtering, but a low-temperature sputtering method in which plasma is confined around a target using a magnetron and the molded substrate is placed outside the plasma is preferably used. Various conventional methods are used for vacuum deposition, including a resistance heating method, a high frequency induction heating method, and a heating method using an electron beam. There is also a reactive deposition method in which metal is deposited in an oxygen gas atmosphere. Various conventional methods can be used for ion plating, but a high frequency ion plating method in which discharge is performed using a 13.56 MHz high frequency electric field and ions are accelerated using a DC electric field is preferably used. In order to improve the mechanical properties or chemical durability of the transparent conductive layer obtained by these methods, heat treatment (annealing) is carried out during or after film formation.
It is preferable to apply In particular, in the vacuum evaporation method, since the substrate surface is hardly heated during film formation, heat treatment is required after the metal oxide film is formed. In particular, when heat treatment is performed in an oxygen atmosphere such as with electricity, oxidation and crystallization of the metal oxide film progresses, and the transparency, mechanical properties, and chemical durability of the film are significantly improved. The leader tape thus obtained has much better transparency and abrasion resistance than conventional tapes. EXAMPLES The present invention will be explained in more detail with reference to Examples below. All "parts" in the examples are parts by weight. Examples 1-2 Comparative Examples 1-4 100 parts of copolyester (Toyobo KK product, Vylon 300) was mixed with 420 parts of methylene chloride,
Dissolved in a mixture of 420 parts of ethylene chloride, 50 parts of starch, and 15 parts of inorganic powder (5 parts of feldspar fine powder (Canada Indusmin product, Minex7), 5 parts of wet synthetic silica powder (Fuji Davison KK product, Cyroid 308) , and a mixture of 5 parts of dry synthetic silica fine powder (Nippon Aerosil KK product, R972)] and kneaded in a ball mill for 120 hours to prepare a coating solution. The coating solution was roll coated onto one side of a polyethylene terephthalate film (thickness: 25 μm) so that the film thickness after drying the solvent at 100 to 110° C. was 5 μm. The obtained roughened film (surface roughness: 3 μm) is hereinafter referred to as film (I-1). “NUC” is placed on the roughened surface of the film (I-1).
Silicon Primer” (Nippon Unicar KK product)
A mixed alcohol solution containing 0.7 parts of methanol, ethanol, and isopropanol was applied using a gravure roll coater and dried at 150°C for 1 minute. The thickness of the organosilicon compound layer after drying was 700 Å. This film is hereinafter referred to as film (Ro-1). In addition, SiO ₂ was vacuum-deposited on the roughened surface of another film (I-1) under 7×10 ^-5 Torr as a deposition material. Inorganic The film thickness of the silicon compound layer was 800 Å.Hereinafter, this will be referred to as film (HA-1). Film (I-1), film (RO-1), film (HA- ₁ ) were ₃ and 5 parts of SnO ₂ as a deposition material at 8×10 ^-5 Torr.
Vacuum deposited. The thickness of the metal oxide layer was 100 Å. Subsequently, heat treatment was performed at 150°C to obtain a transparent conductive layer. In exactly the same manner, an organic or inorganic silicon compound layer (A) and a transparent conductive layer (D), or only a transparent conductive layer (B) were formed on a polyethylene terephthalate film that was not roughened. The six types of samples mentioned above were slit into 1/2 inch width to make leader tapes. Table 1 shows the transmittance, surface resistance, and abrasion resistance of these leader tapes. Abrasion resistance (still time) is measured by scanning a rotary magnetic head over the same position on the tape while the tape is stationary, and scraping away the film in this area.
This is the time until scratches appear on the support.

[Table] Comparative example 5 Polyethylene terephthalate film (thickness 25
μm) was bombarded with argon plasma, and then vacuum evaporated under 8×10 ⁻⁵ Torr using a mixture of 95 parts of IN ₂ O ₃ and 5 parts of SnO ₂ as a deposition material. The thickness of the metal oxide layer was 100 Å. Subsequently, heat treatment was performed at 150°C to obtain a transparent conductive layer. Next, reactive vapor deposition was performed on the transparent conductive layer using SiO as a vapor deposition material in an oxygen atmosphere of 5×10 ^-4 Torr. The thickness of the silicon oxide layer was 500 Å. The above sample was slit into 1/2 inch width to make a leader tape. The leader tape had a surface resistance of 5×10 ⁴ Ω/□ and a transmittance of 80%. Abrasion resistance was examined in the same manner as in Example 1, and the still time was 30 seconds. Examples 3-4, Comparative Examples 6-9 On the roughened surface of a polyethylene terephthalate film (thickness 25 μm) that had been roughened by sandblasting to a surface roughness of 2 μm,
“NUC Silicon Primer” (Nippon Unicar KK
Product) A mixed alcohol solution containing 0.5 parts of methanol, ethanol, and isopropanol was applied using a gravure roll coater and dried at 150°C for 1 minute. The thickness of the organosilicon compound layer after drying is 600
It was Å. Hereinafter, this will be referred to as film (I-2). In addition, the surface roughness has been reduced to 2 by sandblasting.
On the roughened surface of another polyethylene terephthalate film (thickness: 25 μm), which had been roughened to a thickness of μm, SiO ₂ was vacuum deposited as a deposition material under 7×10 ⁻⁵ Torr. The thickness of the inorganic silicon compound layer was 700 Å. Hereinafter, this will be referred to as film (Ro-2). A mixture consisting of 95 parts of In ₂ O ₃ and 5 parts of SnO ₂ was applied to polyethylene terephthalate films, films (I-2) and films (R-2) whose surfaces were only roughened by sandblasting and did not form a silicon compound layer. The material to be deposited was vacuum deposited under 8×10 ⁻⁵ Torr. The thickness of the metal oxide layer was 100 Å. Subsequently, heat treatment was performed at 150°C to obtain a transparent conductive layer. In exactly the same manner, an organic or inorganic silicon compound layer (A) and a transparent conductive layer (B), or only a transparent conductive layer (B) were formed on a polyethylene terephthalate film that was not roughened. The six types of samples mentioned above were slit into 1/2 inch width to make leader tapes. Table 2 shows the transmittance, surface resistance, and abrasion resistance of these leader tapes. Abrasion resistance (still time) is measured by scanning a rotating magnetic head over the same position on the tape while the tape is stationary, and removing the film in this area.
This is the time until scratches appear on the support.

[Table] Comparative example 10 Polyethylene terephthalate film (thickness 25
[mu]m) was bombarded with air plasma, and then a mixture of 95 parts of In ₂ O ₃ and 5 parts of SnO ₂ was used as a deposition material and vacuum evaporated under 8×10 ⁻⁵ Torr.
The thickness of the metal oxide layer was 100 Å. Subsequently, heat treatment was performed at 150°C to obtain a transparent conductive layer. Next, reactive vapor deposition was performed on the transparent conductive layer using SiO as a vapor deposition material in an oxygen atmosphere of 5×10 ⁻⁴ Torr. The thickness of the silicon oxide layer was 500 Å. The above sample was slit into 1/2 inch width to make a leader tape. The leader tape had a surface resistance of 5×10 ⁴ Ω/□ and a transmittance of 80%. Abrasion resistance was examined in the same manner as in Example 3, and the still time was 30 seconds. Example 5 Gamma methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical KK product KBM503) was applied to the roughened surface of a polyethylene terephthalate film (thickness 25 μm) that had been roughened to a surface roughness of 2 μm by sandblasting. A coating solution dissolved in a mixed solvent of 10 parts of ethanol and 10 parts of water was applied using a gravure roll coater and coated at 150℃ for 1 hour.
Dry for a minute. The thickness of the organosilicon compound layer after drying was 700 Å. Furthermore, a mixture of 95 parts of In ₂ O ₃ and 5 parts of SnO ₂ was vacuum-deposited on the organosilicon compound layer as a deposition material under 8×10 ⁻⁵ Torr. The thickness of the metal oxide layer was 100 Å. Subsequently, heat treatment was performed at 150°C to obtain a transparent conductive layer. The above sample was slit into 1/2 inch width to make a leader tape. The leader tape had a surface resistance of 4×10 ⁴ Ω/□ and a transmittance of 68%. Wear resistance was examined in the same manner as in Example 3.
The still time was 9 minutes. Example 6 Organosilicon compound was converted into vinyltris(β-methoxyethoxy)silane (Shin-Etsu Chemical KK product)
A leader tape with a width of 1/2 inch was obtained in exactly the same manner as in Example 5, except that KBC1003) was used.
The surface resistance of the leader tape is 6×10 ⁴ Ω/□,
The transmittance was 68%. Wear resistance was examined in the same manner as in Example 3.
The still time was 9 minutes.

Claims (1)

[Claims] 1 A silicon compound layer (A) is provided on the rough surface of a transparent flexible support plate whose surface is roughened at least on one side, and a transparent conductive layer made of a metal oxide is further provided on the layer (A).
A leader tape comprising (B) laminated, wherein the rough surface has a roughness of 2 μm to 3.5 μm.