JPH05274640A - Leader tape for magnetic tape - Google Patents

Abstract

PURPOSE:To obtain the leader tape having an excellent antistatic property, non-tacky adhesiveness, traveling property and wear resistance by laminating and providing coating layers contg. an aq. resin, antistatic aq. high-polymer compd. having a sulfone group or sulfonato group and a lubricant on at least one surfaces of a polyester film. CONSTITUTION:Poly (ethylene terephthalate), poly (ethylene naphthalate), etc., are used for the leader tape and various kinds of stabilizers, UV absorbents, lubricants, pigments, antioxidants, plasticizers, etc., may be incorporated therein. The thickness thereof is specified to 10 to 100mum in order to prevent elongation and cut. Starch, methyl cellulose, urethane resins, etc., are used for the aq. resin and are incorporated into the coating layers at 10 to 90wt.% of the weight of the components constituting these layers. Vinyl sulfonic acid, sodium vinyl sulfate, etc., are used for the aq. high-polymer compd. and acrylic acid, methacrylic acid, etc., are polymerized therewith. Anionic and cationic surfactants are used for the lubricant to be incorporated into the coating layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leader tape which is connected to both ends of a magnetic recording medium such as an audio tape, a memory tape and a video tape.

[0002]

2. Description of the Related Art In order to optically detect the end of a magnetic tape in a magnetic recording device such as a video tape recorder, leader tapes made of plastic film are provided at both ends of the magnetic tape. It is connected. Films such as vinyl chloride and polyethylene terephthalate have been used for these leader tapes, but since these films have high electrical resistance and are easily charged, dust and dust around them adhere to the film, which causes magnetic tape or magnetic There was a shift to the head, which caused dropout and a decrease in the S / N ratio.
In order to prevent such a defect, various methods of applying antistatic treatment to the leader tape, for example, a method of kneading an antistatic agent into a base film or a method of applying only an antistatic agent to a base film (Japanese Patent Laid-Open No. 52-145022). No. gazette) is proposed. But with this method,
It has a drawback that the antistatic property is insufficient or an antistatic agent adheres to a magnetic head or the like during running, so that the antistatic effect is apt to be sharply lowered by running the tape.

A method of providing an antistatic layer in which an antistatic agent is bound to a vinyl chloride-vinyl acetate copolymer and an isocyanate compound on a base film (Japanese Patent Publication No. 55-4).
3189 publication) is also proposed. According to such a method, the decrease in the antistatic effect due to the running of the tape can be reduced, but the antistatic effect cannot be expected with a small amount of the antistatic agent, and an antistatic agent is added to improve the antistatic effect. When the amount is increased, there are drawbacks that the antistatic layer exhibits tackiness and that the running of the tape becomes unstable due to insufficient slipperiness.

Further, a method of coating and curing a composition containing an acrylic cation resin having a quaternary ammonium salt group added to a base film as a main component (JP-A-59-2827).
9) or indium oxide or the like. However, in such a method, since the adhesion of the cured coating film is poor and the abrasion resistance is inferior, there is a drawback that the coating film falls off during running of the tape and adheres to the magnetic head or the like, causing dropout. On the other hand, the method of providing the antistatic layer by vapor deposition is high in manufacturing cost and is not practical.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in view of the above problems, a leader tape having a specific structure is excellent in antistatic property, non-adhesive property, running property and abrasion resistance. As a result, they have completed the present invention. That is, the gist of the present invention is to coat at least one surface of a polyester film with (a) an aqueous resin, (b) an antistatic aqueous polymer compound having a sulfo group or a sulfonato group, and (c) a lubricant. The present invention resides in a leader tape for magnetic tape in which layers are laminated.

The present invention will be described in detail below. The polyester referred to in the present invention means an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid or an ester thereof and ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol. It is a polyester produced by polycondensing a glycol such as.

The polyester composed of these acid component and glycol component can be produced by arbitrarily adopting a commonly used method. For example, a transesterification reaction is carried out between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, or an aromatic dicarboxylic acid and a glycol are directly esterified to give a bisglycol ester of a substantially aromatic dicarboxylic acid. Or a low polymer thereof is formed and then polycondensed at a temperature of 240 ° C. or higher under reduced pressure. At this time, ordinary catalysts, stabilizers, various additives and the like can be optionally used.

Typical examples of such polyesters include poly (ethylene terephthalate), poly (ethylene naphthalate), poly (cyclohexane dimethylene terephthalate) and the like. This polyester may be a homopolymer, a polymer obtained by copolymerizing a third component, or a mixture of these polyesters. Further, various stabilizers, ultraviolet absorbers, lubricants, pigments, antioxidants and plasticizers may be added to the polyester film.

The thickness of the film is usually 5 to 200 μm, but is preferably 10 to 100 μm. When the thickness of the film is less than 5 μm, the mechanical strength is insufficient and the film stretches, It will be cut off. If the thickness of the film exceeds 200 μm, the running property of the film tends to deteriorate. The aqueous resin blended in the coating layer of the leader tape of the present invention refers to a water-soluble or water-dispersible resin, and examples thereof include starch, cellulose derivatives such as methyl cellulose and hydroxyethyl cellulose, alginic acid, gum arabic, gelatin, and polyacrylic. Examples thereof include sodium acid, polyacrylamide, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, urethane resins, acrylic resins, polyamide resins, ether resins, epoxy resins, polyester resins and the like. In the present invention, urethane resins, acrylic resins, and polyester resins are particularly preferable.

As the urethane resin, an aqueous urethane resin whose main component is polyisocyanate, polyol, chain extender, crosslinking agent, etc. can be used. In making it aqueous, polyisocyanate,
It is a general method to use a polyol and a chain extender having a hydrophilic group introduced therein. It is also a well-known method to react an unreacted isocyanate group of polyurethane with a compound having a hydrophilic group.

The main components of the acrylic resin are an alkyl acrylate or an alkyl methacrylate, a carboxyl group or a salt thereof, an acid anhydride group, a sulfo group or a sulfonate group, an amide group, an amino group, a hydroxyl group,
An aqueous acrylic resin obtained by copolymerizing a vinyl monomer having a reactive functional group such as an epoxy group can be used.

Examples of the dicarboxylic acid component of the polyester resin include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, and oxybenzoic acid. Oxycarboxylic acids such as acids and their ester-forming derivatives can be used.
Examples of the glycol component of the polyester resin include aliphatic glycols such as ethylene glycol, 1,4-butanediol, diethylene glycol and triethylene glycol, alicyclic glycols such as 1,4-cyclohexanedimethanol, and p-xylenediol. Aromatic diols, poly (oxyalkylene) glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol can be used.

As the polyester resin, not only a saturated linear polyester containing the above ester-forming component but also a compound having a trivalent or higher valent ester-forming component or a compound having a reactive unsaturated group is used as a polyester component. May be Polyester resin is
Those having functional groups (sulfo group, carboxyl group, phosphono group, sulfonato, carboxylato, phosphonate group) such as sulfonic acid, carboxylic acid, phosphoric acid or salts thereof in order to improve solubility and dispersibility in water Preferably.

In the present invention, the above-mentioned aqueous resins may be used in appropriate combination. Further, the mixing ratio of the aqueous resin is 10 wt% to 9 with respect to the components constituting the coating layer.
The range of 0 wt% is preferable, and 20 wt% is more preferable.
% To 80 wt%. Examples of the antistatic aqueous polymer compound having a sulfo group or a sulfonato group used in the present invention include the following. That is, vinyl sulfonic acid, sodium vinyl sulphonate, potassium vinyl sulfonate, lithium vinyl sulfonate, ammonium vinyl sulfonate, allyl sulfonic acid, sodium allyl sulfonate, potassium allyl sulfonate, lithium allyl sulfonate, ammonium allyl sulfonate, meta Copolymerizable with at least one of monomers such as ryl sulfonic acid, sodium methallyl sulfonate, potassium methallyl sulfonate, lithium methallyl sulfonate, ammonium methallyl sulfonate, acrylic acid sulfopropyl ester or its salt Examples thereof include those obtained by copolymerizing at least one kind of monomer by a method such as an emulsifier-free emulsion polymerization method or a solution polymerization method.

Examples of such copolymerizable monomers include acrylic acid or methacrylic acid and methyl, ethyl,
Propyl, butyl, amyl, hexyl, heptyl, octyl, esters of lower alcohols such as 2-ethylhexyl and hydroxyalkyl esters of acrylic acid or methacrylic acid, alkoxyalkyl esters, alkyldialkylene glycol esters, alkyltrialkylene glycol esters, Glycidyl ester,
Examples thereof include N, N-dialkylaminoalkyl esters. Further, styrene and styrene derivatives such as monoalkyl styrene, dialkyl styrene and trialkyl styrene are also included.

In the present invention, among the above-mentioned compositions, the antistatic aqueous polymer compound having a sulfo group or a sulfonate group is a copolymer of at least one of vinyl sulfonic acid or vinyl sulfonate. The component is preferably contained in the range of 10 to 70 mol%, more preferably 15 to 50 mol%. If it is less than 10 mol%, the copolymer itself often does not have sufficient antistatic ability, and if it exceeds 70 mol%, the polymerizability may deteriorate.

The proportion of the antistatic aqueous polymer compound having a sulfo group or a sulfonato group in the present invention is usually 10 to 90 with respect to the components constituting the coating layer.
It is in the range of wt% and preferably in the range of 20 to 80 wt%. If the blending ratio is less than 10 wt%, the antistatic effect may not be sufficiently exhibited. Also, 90 wt
If it exceeds%, the coating layer itself becomes brittle, which is not preferable.

Examples of the lubricant used in the present invention include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorochemical surfactants, organic carboxylic acids and their derivatives, and higher grades. Aliphatic alcohols, paraffins, waxes, organopolysiloxanes and the like can be mentioned, with water-soluble or water-dispersible polyolefins being particularly preferred.

Examples of such polyolefins include (i) waxes, resins and rubbers made of homo- or copolymers of 1-olefin unsaturated hydrocarbons such as ethylene, propylene, 1-butene and 4-methyl-1-pentene. Objects such as polyethylene, polypropylene, poly-1-
Butene, poly-4-methyl-1-pentene, ethylene-
Propylene copolymer, ethylene-1-butene copolymer,
Propylene-1-butene copolymer (ii) Rubber-like copolymer of two or more of the above-mentioned 1-olefins and a conjugated or non-conjugated diene, for example, ethylene-propylene-butadiene copolymer, ethylene-propylene-dicyclopentadiene Copolymer, ethylene-propylene-
Ethylidene norbornene copolymer, ethylene-propylene-1,5-hexadiene copolymer or isobutene-isoprene copolymer (iii) Copolymer of 1-olefin and conjugated or non-conjugated diene, for example ethylene-butadiene copolymer , Ethylene-butadiene copolymer, ethylene-ethylidene norbornel copolymer (iv) 1-olefin, especially copolymer of ethylene and vinyl acetate and its complete or partially saponified product (v) 1-olefin alone or A graft polymer obtained by grafting the above-mentioned conjugated or non-conjugated diene or vinyl acetate onto a copolymer and its complete or partially saponified product (vi) 1-olefin, especially a copolymer of ethylene and acrylic acid It has a skeleton, and it is used by dissolving or dispersing these in water. It is possible.

In order to dissolve or disperse the polyolefin in water and stabilize it so as not to cause aggregation, a conventionally known surfactant may be used in combination,
A method in which a hydrophilic polymer such as a water-soluble polyester is allowed to coexist during dispersion is also effective. Further, by introducing a vinyl compound having a hydrophilic group such as a carboxyl group, a sulfo group, an amino group, a polyether, an alkylolamide group or a salt thereof into the skeleton of the polyolefin by copolymerization or grafting, water-soluble It is also possible to use a material which is easily made into water or dispersed in water.

The mixing ratio of the lubricant used in the present invention is
The range of 0.1 to 20 wt% with respect to the components constituting the coating layer is preferable, and more preferably 0.5 wt% to 10
It is in the range of wt%. Blending of the lubricant makes the surface of the coating layer slip well and significantly improves the abrasion resistance of the surface of the coating layer. If the blending ratio of the lubricant is too small, the above effect may not be sufficiently exhibited, and if it is too large, the surface of the coating layer may be sticky.

In order to improve blocking and the like in the coating layer, it is preferable to add a cross-linking agent, inorganic particles, organic particles and the like, and if necessary, a defoaming agent, a coating property improving agent and an increasing agent. You may contain a viscous agent, an antioxidant, a ultraviolet absorber, a dye, etc. As a method for applying the above-mentioned coating liquid to a polyester film, Yuji Harasaki, Maki Shoten, 197
A method of applying a coating liquid outside the biaxially stretched polyester film manufacturing process using a reverse roll coater, a gravure coater, a rod coater, an air doctor coater or another coating device shown in "Coating Method" issued in 9 years, More preferably, the method of applying in a film manufacturing process is mentioned. As a method of applying in the film manufacturing process, a coating solution is applied to a polyester unstretched film, and sequentially or simultaneously, a method of biaxially stretching, a uniaxially stretched polyester film,
Furthermore, a method of stretching in a direction perpendicular to the uniaxial stretching direction,
Alternatively, there is a method of applying it on a biaxially stretched polyester film and further stretching it in the transverse and / or longitudinal directions.

The above-mentioned stretching step is preferably 60 to 13.
It is carried out at 0 ° C., and the stretching magnification is at least 4 times or more, preferably 6 to 20 times in terms of area magnification. The stretched film is heat-treated at 150 to 250 ° C. Further, it is preferable that the maximum temperature of the heat treatment and / or occasional relaxation is 0.2 to 20% in the longitudinal direction and the transverse direction in the cooling zone at the exit of the heat treatment. In particular, the coating solution is applied to a uniaxially stretched polyester film stretched 2 to 6 times by a roll stretching method at 60 to 130 ° C., and appropriate drying is performed, or the polyester film uniaxially stretched film is immediately stretched without being dried. 2 at 80 to 130 ° C in the direction perpendicular to the direction
It is preferable to stretch the film by 6 to 6 times and heat-treat at 150 to 250 ° C. for 1 to 600 seconds.

According to this method, the coating layer can be dried at the same time as stretching, and the thickness of the coating layer can be reduced according to the stretching ratio, and a film suitable as a leader tape can be manufactured at a relatively low cost. it can. The coating solution according to the present invention may be applied to only one side of the polyester film, or may be applied to both sides. When coated on only one side, a coating layer other than the coating solution of the present invention may be formed on the opposite side, if necessary, to impart other properties to the polyester film of the present invention.

The film may be subjected to a chemical treatment or an electric discharge treatment before the coating in order to improve the coating property and the adhesive property of the coating agent on the film. The thickness of the coating layer is 0.01 to 3μ
The range of m is preferable, and more preferably 0.02-1 μm.
The range is m. If the thickness of the coating layer is less than 0.01 μm, uneven coating is likely to occur, and if it is more than 3 μm, curling is likely to occur.

The light transmittance of the leader tape in the present invention is preferably 20% or more, more preferably 50% or more. If the light transmittance is less than 20%, many errors occur when the end of the magnetic tape is detected by the photoelectric sensor. In addition, if necessary, characters,
A printing layer such as a mark or a cleaning layer may be provided.

[0027]

The present invention will now be described in more detail with reference to the examples of the present invention, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples and comparative examples, "part" means "part by weight (solid content)".
Evaluations in Examples and Comparative Examples were performed as follows.

(1) Antistatic property The surface resistivity of the coating surface side of the film is 50 mm in inner electrode and 70 in outer electrode manufactured by Yokogawa / Hewlett-Packard.
Using the 16008A (trade name), which is a concentric circular electrode with mm diameter, and the 4329A (trade name), a high resistance meter of the same company,
A voltage of 100 V was applied and measured in an atmosphere of 3 ° C. and 50% RH.

(2) Sliding property The coated surface and the coated surface of a film cut into a width of 15 mm and a length of 150 mm are superposed on a smooth glass plate, a rubber plate is placed on the coated surface, and a load is further applied on the rubber plate. The film was placed (contact pressure 2 g / cm ² ) and the films were slid at 20 mm / min to measure the frictional force. The friction coefficient at the time of sliding 5 mm was defined as the dynamic friction coefficient (μd). The judgment criteria are as follows. μd ≦ 0.50 ∘ 0.50 <μd ≦ 0.70 ∘ Δ 0.70 <μd ∘ × The measurement was performed in an atmosphere of 23 ° C. and 50% RH.

(3) Non-adhesiveness The coated surface and the non-coated surface of the film are overlapped,
After applying a pressure of 10 kg / cm ² in an atmosphere of 80% RH and pressing for 20 hours, the peel strength (Fp) was measured according to the method of ASTM D-1893. The criterion is
It is as follows. Fp ≦ 50 g …… ○ 50 g <Fp ≦ 200 g …… △ 200 g <Fp …… ×

(4) Abrasion resistance Using a Haydon 14 type surface tester manufactured by Shinto Kagaku Co.,
A sapphire stylus having a tip radius of 0.05 mm was run on the coated surface of the film at a speed of 100 m / min to measure the coating strength of the coated surface. The strength of the coating film was determined by observing the film after measurement with an optical microscope of 200 times, reading the load (Fc) at which the coating film started to be peeled off by a stylus, and following the criteria below. Fc ≧ 50 g ・ ・ ・ ○ 50 g> Fc ≧ 10 g ・ ・ ・ △ 10 g> Fc ・ ・ ・ ×

(5) Light transmittance Double beam type spectrophotometer (228 manufactured by Hitachi, Ltd.)
Type) with a tungsten lamp light source at a wavelength of 35
The light transmittance was continuously measured in the range of 0 to 800 nm, and the light transmittance at a wavelength of 550 nm was read from the recording chart.

Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.65 and containing added particles was melt extruded at 280 to 300 ° C. to give about 6
Extrude while applying static electricity on a 0 ° C cooling drum,
Made into a sheet. Then, after stretching 3.5 times in the longitudinal direction at 83 ° C, one side of this longitudinally stretched film is coated with a coating solution having the following composition, and stretched 3.2 times in the transverse direction at 110 ° C and at 220 ° C. Heat treatment was performed to obtain a film having a thickness of 38 μm and having a coating layer having a thickness of 0.05 μm. The obtained film was slit into a 1/2 inch width to obtain a leader tape for video tape.

[0034]

(Table 1) Composition of coating liquid Polyester aqueous dispersion A (56 mol% terephthalic acid, 40 mol% isophthalic acid, 4 mol% 5-sodiumsulfoisophthalic acid, 70 mol% ethylene glycol, 13 mol% diethylene glycol, 1 Aqueous dispersion of polyester consisting of 17 mol% of 4-butanediol) 67 parts; SVS-EA-MA-DMAEMA copolymer (copolymer composition SVS 30 mol%, EA 25 mol%, MA 25 mol%, DMAEMA 20 mol% ) Water dispersion B 30 parts; polyethylene water dispersion C (Toho Chemical Industry Co., Ltd. Hitec E4B) 3 parts;

However, the symbols in parentheses indicate the following. SVS: sodium vinyl sulfonate, DMAEMA:
Dimethylaminoethyl methacrylate, EA: ethyl acrylate, MA: methyl acrylate The obtained leader tape was connected to the end of the video tape and used, and good results were obtained. The characteristics of the obtained leader tape are shown in Table 1 below.

Example 2 Except that the coating solution in Example 1 was changed as follows:
A leader tape was obtained in the same manner as in Example 1.

(Table 2) Composition of coating liquid 62 parts of polyester water dispersion A; 30 parts of water dispersion B composed of SVS-EA-MA-DMAEMA copolymer; 5 parts of silica sol having an average particle diameter of 0.07 μm; water dispersion of polyethylene Body C part 3

Example 3 Except that the coating liquid was changed as follows in Example 1,
A leader tape was obtained in the same manner as in Example 1.

[Table 3] (Coating liquid composition) Polyester water dispersion A 57 parts; SVS-EA-MA-DMAEMA copolymer (Copolymer composition SVS 15 mol%, EA 30 mol%, MA 30 mol%, DMAEMA 25 mol%) Moisture dispersion D 40 parts; Polyethylene water dispersion C 3 parts

Example 4 Except that the coating liquid was changed as follows in Example 1,
A leader tape was obtained in the same manner as in Example 1.

(Table 4) Composition of coating liquid Polyester water dispersion E (polyester water dispersion consisting of 92 mol% terephthalic acid, 8 mol% 5-sodiumsulfoisophthalic acid, 75 mol% ethylene glycol, and 25 mol% diethylene glycol) 50 parts; Water dispersion E consisting of SVS-MA-EA copolymer (copolymer composition SVS 30 mol%, MA35 mol%, EA35 mol%) 40 parts; Silica sol with average particle size 0.07 μm 5 parts; Polyethylene Water Dispersion G (High Tech E-103N manufactured by Toho Chemical Industry Co., Ltd.) 5 parts

Comparative Example 1 A leader tape was obtained in the same manner as in Example 1 except that the coating liquid was not provided.

Comparative Example 2 The procedure of Example 1 was repeated except that the coating solution was changed as follows.
A leader tape was obtained in the same manner as in Example 1. (Coating liquid composition) 100 parts of polyester aqueous dispersion A

Comparative Example 3 The procedure of Example 1 was repeated except that the coating solution was changed as follows.
A leader tape was obtained in the same manner as in Example 1. (Composition of coating liquid) 100 parts of water dispersion B composed of SVS-EA-MA-DMAEMA copolymer

Comparative Example 4 Except that the coating liquid in Example 1 was changed as follows:
A leader tape was obtained in the same manner as in Example 1.

Table 5 (Composition of coating liquid) 70 parts of polyester water dispersion A; 30 parts of water dispersion B composed of SVS-EA-MA-DMAEMA copolymer The above results are summarized in Table 1 below.

[0043]

[Table 6]

[0044]

INDUSTRIAL APPLICABILITY The leader tape of the present invention is excellent in antistatic property, non-adhesiveness, running property and body abrasion property, and its industrial value is high.

Claims (1)

[Claims] 1. A coating layer containing (a) an aqueous resin, (b) an antistatic aqueous polymer compound having a sulfo group or a sulfonate group, and (c) a lubricant is laminated on at least one surface of a polyester film. Leader tape for magnetic tape