JP2870080B2 - Video cassette tape - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a video cassette tape.

2. Description of the Related Art As a video cassette tape having a tape and a guide pin, a tape using a guide pin having a specific surface roughness is known (for example, Japanese Patent Application Laid-Open No. 61-192091).

[Problems to be Solved by the Invention] However, the above-mentioned conventional video cassette tape has a disadvantage that the surface of the tape is damaged by a contacting roll or a guide pin with an increase in a process speed in manufacturing.

In addition, in the conventional device, the S / N (signal / noise ratio) is inadequate during use because the output characteristics are low when recording and reproduction are repeatedly performed, in addition to the same problems as described above. There were drawbacks.

The present invention solves such a problem, and in particular, provides a video cassette tape which is hardly damaged even during use (hereinafter, referred to as having excellent scratch resistance) and which can withstand repeated recording and reproduction (hereinafter, referred to as having excellent output characteristics). The purpose is to provide.

Means for Solving the Problems The present invention is a video cassette tape comprising a tape having a magnetic layer provided on one surface of a base film and guide pins, wherein the guide pins have a surface roughness Rt of 0.005 to 10 μm. A laminate film comprising a layer (A layer) made of a thermoplastic resin A containing particles, the base film being in contact with a guide pin on at least one surface of a layer (B layer) made of a thermoplastic resin B; The surface roughness Ra of the layer is 0.07 μm or less, the ratio Rt / Ra of Rt to Ra on the surface of the A layer is 8 or less, the average particle diameter d of the particles contained in the A layer is 0.01 to 1 μm, and the thickness of the A layer A video cassette tape characterized in that the ratio t / d of the average particle diameter d to the average particle diameter d of the particles is 0.1 to 3, and the content of the particles in the A layer is 0.5 to 30% by weight. It is.

Thermoplastic resins A and B constituting the base film of the present invention
May be the same or different types, polyester,
Polyolefin, polyamide, polyphenylene sulfide and the like are not particularly limited, but are particularly polyester, especially ethylene terephthalate, ethylene α, β
-Scratch resistance is further improved when at least one structural unit selected from -bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate and ethylene 2,6-naphthalate units is a main component. Is desirable. Further, when the thermoplastic resin A constituting the present invention is crystalline, it is highly desirable because scratch resistance is further improved. The crystallinity here indicates that it is not so-called amorphous, and quantitatively the cold crystallization temperature Tcc in the crystallization parameter is detected, and the crystallization parameter ΔTcg is 150 ° C or less. . Further, when the heat of fusion (change in enthalpy of fusion) measured by a differential scanning calorimeter shows a crystallinity of 7.5 cal / g or more, scratch resistance is further improved, which is extremely desirable.
Further, in the case of a polyester containing ethylene terephthalate as a main component, scratch resistance is further improved, which is particularly desirable.

In addition, as long as the present invention is not impaired, at least one selected from the thermoplastic resins A and B may be mixed with another type of thermoplastic resin, or a copolymer may be used. Further, as long as the object of the present invention is not impaired, organic additives such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers are usually added to at least one selected from thermoplastic resins A and B. It may be.

The average particle diameter d of the particles in the layer A of the substrate film constituting the present invention is 0.01 to 1 μm from the viewpoint of scratch resistance and output characteristics.
m, and preferably 0.01 to 0.5 μm when a magnetic layer is provided on the A layer side, and 0.03 to 1 μm when no magnetic layer is provided.

The content of the particles in the layer A of the substrate film of the present invention is
It is necessary that the content be 0.5 to 30% by weight, preferably 1 to 20% by weight, more preferably 2 to 15% by weight. If the content is more than the above range, the output characteristics cannot be satisfied, and if the content is less, the scratch resistance becomes poor, which is not preferable.

Further, the ratio t / d of the thickness t of the layer A of the substrate film of the present invention to the average particle diameter d of the particles contained in the layer A is 0.1 to 3, preferably 0.2 to 2, more preferably 0.3 to 1.5. Must be within the range. If t / d is smaller than the above range, the scratch resistance becomes poor, and if it is larger, the output characteristics become poor, which is not preferable.

Further, it is not particularly necessary that the B layer on the magnetic layer side of the base film of the present invention contains particles,
0.005 to 0.5 μm, especially 0.01 to 0.4 μm particles are 0.001 to 0.
When the content is 5% by weight, particularly 0.005 to 0.3% by weight, the scratch resistance and the output characteristics are further improved, so that it is desirable.

The particles of the substrate film of the present invention have a particle size ratio (particle major axis / minor axis) of from 1.0 to 1.3, and particularly, in the case of spherical particles, the scratch resistance and the output characteristics are further improved. desirable. The particles of the present invention are particularly desirable when the single particle index in the base film is 0.7 or more, preferably 0.9 or more, because the scratch resistance and the output characteristics are further improved. The particles used in the present invention have a relative standard deviation of 0.6
Below, preferably 0.5 or less, scratch resistance and output characteristics are further improved, so that it is desirable.

The type of particles used in the present invention is not particularly limited, but substantially spherical silica particles resulting from colloidal silica,
There are particles made of cross-linked polymer (eg cross-linked polystyrene), etc., especially when the temperature at 10% by weight loss (measured using a thermogravimetric analyzer in nitrogen; heating rate 20 ° C / min) is 380 ° C or more. Crosslinked polymer particles having a high degree of crosslinking are particularly desirable because scratch resistance and output characteristics are further improved. Spherical silica originating from colloidal silica is particularly desirable because it has a low sodium content produced by the alkoxide method, and substantially spherical silica has better scratch resistance and output characteristics. However, other particles, such as calcium carbonate, titanium dioxide, and alumina, can be used properly by appropriately controlling the ratio of the thickness t of the thermoplastic resin A layer to the average particle size d.

The substrate film constituting the present invention is a film obtained by biaxially orienting a laminated film composed of the above composition. A uniaxial or non-oriented film is not preferred because scratch resistance becomes poor. While the extent of this orientation is not particularly limited, the output characteristic when the Young's modulus is a measure of the degree of molecular orientation of the polymer is longitudinally, 350 kg / mm ² or more in both the width direction, scratch resistance and further improved Very desirable. The upper limit of the Young's modulus, which is a measure of the degree of molecular orientation, is not particularly limited, but usually about 1500 kg / mm ² is the manufacturing limit.

The surface roughness Ra of the layer A constituting the present invention is 0.07 μm or less, preferably 0.06 μm from the viewpoint of output characteristics and scratch resistance.
m, more preferably 0.05 μm or less. Further, the ratio Rt / Ra of Rt to Ra on the surface of the layer A is 8.0 or less, preferably 7.5 or less, more preferably 7.0 or less from the viewpoint of output characteristics and scratch resistance.

When the thickness of the layer A constituting the present invention is 0.01 to 1 μm, preferably 0.02 to 0.5 μm, it is particularly desirable because the scratch resistance and the output characteristics are further improved. When the thickness unevenness of the layer A constituting the present invention in the width direction is 25% or less, more preferably 20% or less, it is particularly desirable because output characteristics and scratch resistance are further improved.

When the total reflection Raman crystallization index of the surface of layer A constituting the present invention is 20 cm ^-1 or less, scratch resistance and output characteristics are further improved, which is particularly desirable. Further, the surface particle concentration ratio measured by the secondary ion mass spectrum on the surface of the layer A is not particularly limited, but the surface particle concentration ratio is 1/10.
In particular, when the ratio is 1/50 or less, scratch resistance and output characteristics are further improved, which is particularly desirable.

The present invention is a video cassette tape in which a magnetic layer is provided on one side of the base film. The type of magnetic powder used is not particularly limited, but ferromagnetic powder, among which γ-Fe
₂ O ₃ , Co-containing γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co-containing Fe ₃ O ₄ , CrO ₂ etc.
Alternatively, metals or alloys such as Fe, Co, and Fe—Co are preferably used.

The magnetic powder can be made into a magnetic paint using various binders.Generally, a thermosetting resin-based binder and a radiation-curable binder are preferable, and as other additives, a dispersant, a lubricant, and an antistatic agent are used according to a conventional method. May be used. For example, a binder made of vinyl chloride / vinyl acetate / vinyl alcohol copolymer, polyurethane prepolymer and polyisocyanate can be used.

Although the thickness t _M of the magnetic layer of the video cassette tape of the present invention is not particularly limited, the ratio t / t _M to the thickness t (one layer) of the A layer is not limited.
0.002-10, especially 0.01-10, more preferably 0.01-5
It is preferable that the ratio is within the range, since the output characteristics and the scratch resistance are further improved. Also, the value of t _M is 0.5 to
A range of 5 μm is desirable because output characteristics and scratch resistance are further improved.

The guide pin referred to in the present invention is a function of guiding the tape by sliding the tape on the tape while the tape is running, while being in the video cassette tape and in contact with the non-magnetic surface side of the tape. Pin.

First, the guide pins used for the video cassette tape of the present invention are preferably made of resin from the viewpoint of scratch resistance and output characteristics. As the resin used as the guide pin, a thermoplastic resin is preferable in terms of scratch resistance and output characteristics. Among them, polybutylene terephthalate, polyoxymethylene, polyamide, tetrafluoroethylene and the like are preferably used, and it is particularly preferable that 60% by weight or more thereof is polyoxymethylene. In this case, an antistatic agent, an antioxidant, a lubricant, fine particles, and the like may be added to the resin.

Further, when the diameter of the guide pin is 3 to 10 mm, the scratch resistance and the output characteristics are further improved, which is preferable. Although the length of the guide pin is not particularly limited, it is extremely preferable that the length is about 0.5 to 6 mm longer than the width of the tape because scratch resistance is improved.

Furthermore, the winding angle of the tape around the guide pin changes depending on the diameter of the reel, the installation position of the reel, the length of the tape, and the like, but the changing range is 50 to 140 °, particularly 60 to 130 ° C.
It is particularly preferable to satisfy the above range in order to achieve both scratch resistance and output characteristics.

The surface roughness Rt of the guide pins of the video cassette tape of the present invention is 0.005 to 10 μm, preferably 0.01 to 5 μm, and more preferably 0.02 to 2 μm. If the surface roughness Rt of the guide pin is out of this range, the scratch resistance cannot be satisfied.

Next, a method for manufacturing the video cassette tape of the present invention will be described.

First, as a method for incorporating the particles into the thermoplastic resin A, a method in which the particles are made into a slurry of ethylene glycol and kneaded into the thermoplastic resin using a vent-type biaxial kneading extruder without stretching and breaking is used. Is very effective in obtaining a base film having a relationship between the thickness and the average particle size and the content.

As a method of adjusting the content of particles, a method of preparing a high-concentration master by the above method, and diluting it with a thermoplastic resin containing substantially no particles at the time of forming a film, and adjusting the content of particles is known. It is valid.

Next, after drying the thermoplastic resin B, a pellet of the thermoplastic resin A containing a predetermined amount of particles as necessary, it is supplied to a known melt lamination extruder, and extruded into a sheet shape from a slit die, It is cooled and solidified on a casting roll to make an unstretched film. That is, 2 or 3
Using a two- or three-layer extruder, a two- or three-layer manifold or a joining block, the thermoplastic resins A and B are laminated, and two or three-layer sheets are extruded from a die, and an unstretched film cooled by a casting roll is produced. In this case, a static mixer,
The method of installing the gear pump is effective for obtaining a film having the relationship between the thickness and the average particle diameter in the range of the present invention, the content, and the surface layer particle concentration ratio in the desired range without stretching. The use of a rectangular feed block as the merging block is extremely effective in obtaining the relationship between the thickness and the average particle size within the range of the present invention. Further, it is preferable that the melting temperature of the extruder on the thermoplastic resin A side is higher by 10 to 40 ° C. than that on the thermoplastic resin B side, without stretching breakage, the relationship between the thickness and the average particle diameter in the range of the present invention, the content, and the desirability. It is effective to obtain a film having a range of thickness variation, surface particle concentration ratio, and total reflection Raman crystallization index in a range. Although the above description has described the configuration of A / B and A / B / A, it can also be applied to a configuration of three or more layers such as A / B / C. Similarly, using a three-layer manifold or a merging block, the thermoplastic resins A, B, and C are laminated, a three-layer sheet is extruded from a die, and cooled by a casting roll to form an unstretched film.

Next, the unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, first use the sequential biaxial stretching method of stretching in the longitudinal direction, then in the width direction,
The longitudinal stretching is divided into three or more stages and the total longitudinal stretching ratio is
The method carried out at a ratio of 3.0 to 6.5 times is effective for obtaining a film having the relationship between the thickness and the average particle size and the content in the range of the present invention. The stretching temperature in the longitudinal direction varies depending on the type of the thermoplastic resin and cannot be said unconditionally. However, usually, the first stage is set to 50 to 130 ° C., and the second and subsequent stages are set to be higher than the thickness and average within the range of the present invention. It is effective for obtaining a film having a relationship between the particle diameters and a surface layer particle concentration ratio within a desirable range of the present invention. The longitudinal stretching speed is preferably in the range of 5,000 to 50,000% / min. As a stretching method in the width direction, a method using a stenter is generally used. Stretching ratio is 3.0 to 5.0 times, stretching speed is 1,000 to 20,
000% / min, the temperature is preferably in the range of 80 to 160 ° C. Next, this stretched film is heat-treated. In this case, the heat treatment temperature is preferably 170 to 200 ° C, particularly 170 to 190 ° C, and the time is preferably 0.5 to 60 seconds.

Next, a predetermined magnetic layer is applied to the surface of the film opposite to the surface A. The method of applying the magnetic layer can be performed by a known method, but the method of applying with a gravure roll obtains a film having a relationship between the thickness and the average particle diameter in the range of the present invention and a surface layer concentration ratio in a desirable range of the present invention. It is effective for In the drying step after the application, the temperature is preferably set to 90 to 120 ° C.

In addition, the calendering step uses polyamide or polyester for the elastic roll, and is carried out at a temperature in the range of 55 to 100 ° C, particularly 60 to 90 ° C. It is effective for obtaining a film having a surface particle concentration ratio. Furthermore, after curing the magnetic layer of this film, the raw material (wide width) is slit to obtain a pancake.

Thereafter, the video cassette tape of the present invention is obtained from the pancake by using a tape incorporating device such as a V / 0 loader.

Here, the method of manufacturing the guide pin is not particularly limited,
A method in which a lubricant, an additive, fine particles, and the like are preliminarily kneaded with a resin to be used using a super mixer or the like, and then supplied to an extruder to perform injection molding is preferably used.

[Method for Measuring Physical Properties and Method for Evaluating Effect] The method for measuring characteristic values and the method for evaluating effect according to the present invention are as follows.

(1) Average particle size of particles The thermoplastic resin is removed from the film by a plasma low-temperature incineration method to expose the particles. Processing conditions are selected such that the thermoplastic resin is ashed but the particles are not damaged. This is observed with a scanning electron microscope (SEM), and the image of the particles is processed with an image analyzer. The following numerical processing is performed for the number of particles of 5,000 or more by changing the observation position, and the number average diameter D obtained by this is defined as the average particle diameter.

 D = ΣDi / N Here, Di is the equivalent circle diameter of the particles, and N is the number of particles.

(2) Particle size ratio It is the ratio of (average major axis) / (average minor axis) of the individual particles in the measurement of (1). That is, it is obtained by the following equation.

Major axis = ΣD1i / N Minor axis = ΣD2i / N D1i and D2i are the major axis (maximum diameter) and the minor axis (shortest axis) of each particle, and N is the number of particles.

(3) Relative standard deviation of particle diameter The standard deviation σ (= ｛Σ (Di−) calculated from the individual particle diameter Di, the average diameter D, and the number N of particles measured by the method (1).
D) ² / N｝ ^1/2 ) divided by the average diameter D (σ / D).

(4) Single Particle Index A cross section of the film is photographically observed with a transmission electron microscope (TEM) to detect particles. When the observation magnification is set to about 100,000, one particle that cannot be further divided can be observed. When the total area occupied by the particles is A, and the area occupied by the aggregate in which two or more particles are agglomerated is B,
Let (AB) / A be the single particle index. The TEM conditions are as follows. One visual field area: 2 μm ² , measurement was performed at 500 visual fields at different locations.

• Observation magnification: 100,000 times • Acceleration voltage: 100 kV • Section thickness: about 1,000 mm (5) Particle content Select a solvent that dissolves thermoplastic resin but does not dissolve particles, and centrifuge particles from thermoplastic resin. The ratio (% by weight) to the total weight of the particles is defined as the particle content.

(6) Crystallization parameter ΔTcg, heat of fusion Measured using a differential scanning calorimeter (DSC). The measurement conditions for DSC are as follows. That is, 10 mg of a sample is set in a DSC apparatus, melted at a temperature of 300 ° C. for 5 minutes, and then rapidly cooled in liquid nitrogen. The quenched sample is heated at a rate of 10 ° C./min, and the glass transition point Tg is detected. The temperature is further increased, and the crystallization exotherm peak temperature from the glass state is determined to be the cold crystallization temperature Tc.
c. The temperature was further increased, and the heat of fusion was determined from the melting peak. Here, the difference between Tcc and Tg (Tcc−Tg) is defined as a crystallization parameter ΔTcg.

(7) Young's modulus According to the method specified in JIS-Z-1702, use an Instron type tensile tester at 25 ° C and 65%
Measured at RH.

(8) Total reflection Raman crystallization index The total reflection Raman crystallization index was measured, and the half reflection width of 1730 cm ⁻¹ , which is the stretching vibration of the carbonyl group, was taken as the total reflection Raman crystallization index of the surface. The measurement conditions are as follows. However, the measurement depth was about 500 to 1,000 mm from the surface.

Light source Argon ion laser (5,145Å) Sample setting The film surface is pressed against a total reflection prism so that the laser polarization direction (S polarization) and the film longitudinal direction are parallel, and the angle of incidence of the laser on the prism (film thickness direction) Angle) was 60 °.

Detector PM: RCA31034 / Photon Counting System (Hamamatsu C1
230) (supply1,600V) Measurement conditions SLIT 1,000μm LASER 100mW GATE TIME 1.0sec SCAN SPEED 12cm ^-1 / min SAMPLING INTERVAL 0.2cm ^-1 REPEAT TIME 6 (9) Intrinsic viscosity [η] (unit: dl / g) Ortho The value calculated by the following formula from the solution viscosity measured at 25 ° C. in chlorophenol is used. That is, η _SP / C = [η] + K [η] ² · C where η _SP = (solution viscosity / solvent viscosity) −1, and C is the weight of dissolved polymer per 100 ml of solvent (g / 100 ml, usually 1.
2), K is the Haggins constant (0.343). The solution viscosity and the solvent viscosity were measured using an Ostwald viscometer.

(10) Surface layer particle concentration ratio Using secondary ion mass spectrum (SIMS), the concentration ratio of the highest concentration element among the elements originating from the particles in the film to the carbon element of the thermoplastic resin is defined as the particle concentration, Perform a vertical analysis. The ratio A / B between the particle concentration A at the outermost layer particle concentration (point at depth 0) measured by SIMS and the maximum concentration B obtained by further analyzing the depth direction, A / B, was defined as the surface layer particle concentration ratio. The measuring device and conditions are as follows.

Primary ion species: O ₂ ⁺ Primary ion acceleration voltage: 12 KV Primary ion current: 200 nA Raster area: 400 μm □ Analysis area: Gate 30% Measurement vacuum degree: 6.0 × 10 ^-9 Torr E-GUN: 0.5 KV-3.0 A (11) Surface roughness Ra, Rt Measured in accordance with JIS B 0601. The surface roughness of the thermoplastic resin of the substrate was measured under the following conditions, and the measurement was performed 10 times, and the average value of 8 times excluding the maximum and the minimum was used as a value.

-Vertical magnification: 200,000 times-Stylus tip radius: 0.5 µm-Stylus load: 5 mg-Measurement length: 1 mm. Cut-off value: 0.08 mm The surface roughness of the guide pin was measured under the following conditions except for the above.

・ Longitudinal magnification: 50,000 times ・ Measurement length: 4mm (12) Dynamic friction coefficient μk, scratch resistance 1/2 inch width non-magnetic tape on a guide pin with an outer diameter of 6mmφ in an atmosphere of 20 ° C and relative humidity of 60% At an angle θ = πrad and run at a speed of 3.3 cm / s. The outlet tension T2 when the inlet tension T1 was 25 g was measured, and the dynamic friction coefficient μk was calculated from the following equation.

μk = (1 / θ) ln (T2 / T1) = (1 / π) ln (T2 / 25) The scratch resistance is as follows. The number of wounds,
The size of the width and the state of white powder generation were observed with a differential interference microscope. Those with no scratches and no generation of white powder have excellent scratch resistance: excellent, 3 scratches / cm
Those having less than the above and almost no generation of white powder were judged as scratch resistance: good, and the others were judged as scratch resistance: poor.

(13) Output characteristics Record 100% analog signal by signal generator,
From the reproduced signal, S / N was measured by a signal noise measuring instrument and was set to A. Also, the recording and reproduction of the symbol is repeated using the tape on which the same signal is recorded, and the S / N of the tape after 10,000 times is repeated.
Was measured in the same manner as above, and was designated as B. When the reduction in S / N (AB) due to the repetition was less than 6.0 dB, the output characteristics were determined to be good, and when it was more than that, the output characteristics were determined to be poor.

[Examples] The present invention will be described based on examples.

Examples 1-4, and Comparative Examples 1-4 Crosslinked polystyrene particles having different average particle sizes, an ethylene glycol slurry containing silica particles derived from colloidal silica was prepared, and this ethylene glycol slurry was heat-treated at 190 ° C for 1.5 hours. Thereafter, the ester exchange reaction with dimethyl terephthalate, polycondensation, the particles 0.05 ~
Polyethylene terephthalate containing 10% by weight (hereinafter PE
T). At this time, the intrinsic viscosity was adjusted to 0.65 by adjusting the polycondensation time (thermoplastic resin A). In addition, a PET substantially containing particles having an intrinsic viscosity of 0.62 and containing substantially no particles was produced by a conventional method, and was designated as a thermoplastic resin B.

Each of these polymers was dried under reduced pressure at 180 ° C for 6 hours (3
Torr), the thermoplastic resin A is supplied to the extruder 1 and 285
C., and further, the thermoplastic resin B is supplied to the extruder 2 and melted at 282.degree. C., these polymers are combined and laminated by a joining block, and the surface temperature is 30.degree.
And cooled and solidified to form a laminated unstretched film. At this time, the discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the thermoplastic resin A layer. The resin layer A serves as a contact surface with the guide pin.

This unstretched film was stretched 4.0 times in the longitudinal direction at a temperature of 83 ° C. This stretching is performed at the peripheral speed difference between two sets of rolls,
Performed in stages. This uniaxially stretched film is stretched 4.4 times in the width direction at 105 ° C. at a stretching speed of 2,000% / min using a stenter, and is heat-treated at 210 ° C. for 5 seconds under a constant length to obtain a total thickness of 10 μm.
Was obtained.

A magnetic paint is applied to this film using a gravure roll. The magnetic paint was prepared as follows.

・ Γ-Fe ₂ O ₃ 100 parts Average particle size Length: 0.3 μm Needle ratio: 10/1 Coercive force 500 Oe ・ Polyurethane resin 15 parts ・ Vinyl chloride / vinyl acetate copolymer 5 parts ・ Nitrocellulose resin 5 parts・ 3 parts of aluminum oxide powder Average particle size: 0.3 μm ・ 1 part of carbon black ・ 2 parts of lecithin ・ 100 parts of methyl ethyl ketone ・ 100 parts of methyl isobutyl ketone ・ 100 parts of toluene ・ 2 parts of stearic acid The above composition was mixed and dispersed by a ball mill for 48 hours. After that, the kneaded product obtained by adding 6 parts of a curing agent was filtered through a filter to prepare a magnetic coating liquid, applied on the resin B side of the film, magnetically oriented, and dried at 110 ° C. Further, after calendering at a temperature of 75 ° C. and a linear pressure of 250 kg / cm using a small test calender (steel roll / nylon roll, 5 steps), the cake was cured at 70 ° C. for 48 hours to obtain a pancake.

Next, regarding the manufacturing method of the guide pin, first, 6 parts by weight of carbon black is added to polyoxymethylene, and the mixture is pre-kneaded with a super mixer and then supplied to an extruder.
Obtain pellets of polyoxymethylene. The pellet was supplied to an injection molding machine to obtain a guide pin having a diameter of 6 mm and a length of 16 mm.

This polyoxymethylene guide pin was set on a cassette, and a video cassette tape was obtained from the pancake using a loader.

These characteristics are as shown in Table 1. The video cassette tape of the present invention was excellent or good in scratch resistance and output characteristics. Otherwise, the video tape satisfying the scratch resistance and output characteristics was excellent. No cassette tape was obtained.

[Effects of the Invention] The present invention is a video cassette tape composed of a guide pin having a specific surface roughness and a tape provided with a magnetic layer on a base film of which the manufacturing method is devised.
A video cassette tape with excellent output characteristics was obtained. This can correspond to the upscaling for higher image quality of the magnetic recording medium in the future.

Furthermore, in the present invention, the base film used is made of a thermoplastic resin containing particles, and the relationship between the particle size and the film thickness and the content are in a specific range, so that scratch resistance and output characteristics are improved. An excellent video cassette tape has been obtained, and can cope with an increase in processing speed in each application.

Continuation of the front page (56) References JP-A-3-209623 (JP, A) JP-A-3-232178 (JP, A) JP-A-61-110388 (JP, A) (58) Fields studied (Int .Cl. ⁶ , DB name) G11B 5/704 G11B 23/087

Claims (3)

(57) [Claims] 1. A video cassette tape comprising a tape provided with a magnetic layer on one surface of a base film and guide pins, wherein the guide pins have a surface roughness Rt of 0.005 to 10 μm and the base film is made of thermoplastic resin. A laminated film in which a layer (A layer) made of a thermoplastic resin A containing particles is in contact with at least one surface of a layer (B layer) made of resin B and is in contact with a guide pin, and the surface roughness Ra of the A layer is 0.07 μm or less, the ratio Rt / Ra of Rt to Ra on the surface of the A layer is 8 or less, the average particle size d of the particles contained in the A layer is 0.01 to 1 μm, the thickness t of the A layer and the average particle size of the particles. A video cassette tape characterized in that the ratio t / d of the diameter d is 0.1 to 3, and the content of the particles in the layer A is 0.5 to 30% by weight. 2. The video cassette tape according to claim 1, wherein the guide pins are made of a resin, and the material is 60% by weight or more of polyoxymethylene. 3. The winding angle of the tape around the guide pin is 50 to 50.
The video cassette tape according to claim 1 or 2, wherein the angle is in a range of 140 °.