JPH0754620B2 - Transparent sheet material for reel type cassette tape - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transparent sheet material for reel-type cassette tape, which is excellent in transparency, and has excellent permanent antistatic property and slip property. The purpose is to provide a transparent sheet material.

(Prior Art) Conventionally, a slip sheet is provided between a cassette half and a tape of a cassette tape for the purpose of preventing electrostatic charge of the tape or reel of the cassette tape and smooth rotation of the tape or reel. However, since the slip sheet is fixed to the half and the tape rotates in contact with the slip sheet, winding disorder easily occurs and there is a problem in running property. Therefore, a reel-type cassette tape was devised in which the entire reel could be freely rotated by sandwiching the reel with a transparent sheet. FIG. 5 shows an example of a reel type cassette tape, and 4 in the figure is a reel type cassette tape. The cassette tape 4 is fixed to the pair of hubs 10 and 10, and the other ends of the cleaning leader tapes 11 and 11 wound up are connected by a magnetic tape 12 to form a pair of reels 5 and 5. A total of four metal flanges 7 sandwiched by two transparent sheets 6 on both sides of 5, 5 are fitted to the hubs 10 and 10, and the hubs 10 and 10 are paired with a pair of transparent cassette halves 8. The cassette halves 8 and 8 are fitted to each other and fixed by screws 9. Thus, in the reel type cassette tape 4, since the rotations of the reels 5 and 5 are only in contact with each other at the edges of the hubs 10 and 10 in the central portion, the rotation torque is lower than that of the conventional cassette tape, and stable running is achieved. The nature has come to be obtained. As a material for forming the transparent sheet used in this reel type cassette tape, transparency is required so that the rotation state of the reel can be observed from the outside of the cassette half,
Further, it is preferable that it can prevent dust from adhering during punching or assembling work and can remove static electricity generated during tape running, and that it has durability that can maintain its performance even after long-term use. .

Heretofore, as this type of sheet material, there have been proposed those in which an antistatic agent or a lubricant is applied to the surface of a transparent resin sheet, and those in which a resin containing an antistatic agent or a lubricant is applied to the surface of the transparent sheet.

(Problems to be Solved by the Invention) However, in such a conventional sheet material, the antistatic agent and the lubricant are likely to fall off, and the antistatic property and the slipperiness are easily deteriorated. However, there are problems that the lubricant adheres to the tape cassette half and smooth tape running cannot be obtained, and the appearance is impaired.

(Means for Solving Problems) The present invention has been made by paying attention to such conventional problems, and is a reel type which is excellent in transparency and antistatic property and can maintain excellent performance for a long period of time. An object is to provide a transparent sheet material for a cassette tape.

That is, the present invention comprises a transparent base sheet material and a slip layer provided on at least one surface of the base sheet material, wherein the slip layer has a prepolymer having at least one ethylenically unsaturated bond in a molecule. Characterized in that a curable composition containing an oligomer or a monomer as a main component and a coating liquid containing an antistatic agent are applied onto a base sheet material and then cured by irradiation with radiation. It is a transparent sheet material for reel type cassette tapes.

Next, the present invention will be described in more detail.The main feature of the present invention is that a transparent radiation-curable resin layer is used as a resin layer containing an antistatic agent and a lubricant when forming a transparent sheet material. Due to such characteristics, it is possible to provide a transparent sheet material for reel type cassette tape which is transparent and has excellent wear resistance, which can maintain sufficient antistatic property and slip property even after long-term use.

As the base sheet material used in the constitution of the transparent sheet material of the present invention as described above, any conventionally known base sheet material can be used as it is if it is transparent, for example, polyethylene terephthalate, polybutylene terephthalate, ethylene. -Vinyl acetate copolymer, saponified product of ethylene-vinyl acetate copolymer, polyvinyl alcohol, nylon, polypropylene, polyethylene,
Examples thereof include polyvinyl chloride, polycarbonate, polystyrene, cellophane, cellulose diacetate and the like. These base sheet materials preferably have a thickness of 30 to 150 μm.

As the antistatic agent used in the present invention, any conventionally known antistatic agent can be used, and for example, various quaternary ammonium salts, pyridinium salts, various kinds of cationic groups such as primary to tertiary amino groups can be used. Anionic antistatic agent having anionic group such as cationic antistatic agent, sulfonate group, sulfuric acid ester group, phosphoric acid ester group, phosphonate, amphoteric antistatic agent such as amino acid type, amino sulfuric acid ester type, and amino Examples include various surfactant-type antistatic agents such as alcohol-based, glycerin-based and polyethylene glycol-based nonionic antistatic agents, and further polymeric antistatic agents obtained by polymerizing the above-mentioned antistatic agents. Further, it has a tertiary amino group or a quaternary ammonium group, and is a monomer or oligomer which can be polymerized by radiation, such as N, N-dialkyl. Aminoalkyl (meth) acrylate monomer, also polymerizable antistatic agents such as those quaternary compound can be used.

In particular, when such a polymerizable antistatic agent is used, these antistatic agents are integrated with the resin layer to be formed, so that stable antistatic properties can be achieved for a long period of time.

The amount of the antistatic agent used as described above is not particularly limited,
Generally, the obtained transparent sheet material has an electrostatic half-life of 60.
It is preferably set to be less than or equal to seconds.

As the lubricant used as necessary in the present invention, any conventionally known lubricant can be used, for example, a silicone resin, a fluorine resin, specifically a silicone oil for adding a paint: KP-301 (Shin-Etsu Fluorine resin for preventing blocking: Lubron LD-100 (manufactured by Daikin Industries) and the like are useful.

Such lubricants are present in the slip layer which forms about 0.1 to 20
It is preferable to use it in a proportion that occupies weight%.
If it is less than 0.1% by weight, sufficient surface lubricity cannot be achieved, and if it exceeds 20% by weight, further improvement of the surface lubricity effect is not observed, which is not only uneconomical, but also of the lubricant. Bleedout to the surface becomes severe, the transparency and antistatic property of the slip sheet deteriorates, and the lubricant migrates to the magnetic tape, which causes adverse effects such as contaminating the magnetic tape and the magnetic head. .

The radiation-cured slip layer that is used in the present invention and mainly characterizes the present invention is a conventionally known radiation, for example, a compound capable of forming a strong coating film as a polymerized curing by an electron beam or an ultraviolet ray, that is, a molecule. It is formed from a curable composition mainly composed of a prepolymer or oligomer having at least one ethylenically unsaturated bond therein and a monomer.

As such a prepolymer or oligomer,
For example, unsaturated polyesters, polyester acrylates, epoxy acrylates, urethane acrylates,
Polyether acrylate, polyol acrylate,
Various acrylates such as melamine acrylate, polyester methacrylate, epoxy methacrylate, urethane methacrylate, polyether methacrylate,
One or more kinds of various methacrylates such as polyol methacrylate and melamine methacrylate can be used.

Examples of the monomer having an ethylenically unsaturated bond in the molecule include styrene-based monomers such as styrene and α-methylstyrene; methyl acrylate, acrylic acid-
Acrylic esters such as 2-ethylhexyl, methoxyethyl acrylate, butoxyethyl acrylate, butyl acrylate, methoxybutyl acrylate, phenyl acrylate; methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, methoxyethyl methacrylate,
Ethoxymethyl methacrylate, phenyl methacrylate,
Methacrylic acid esters such as lauryl methacrylate; unsaturated carboxylic acid amides such as acrylamide and melacrylamide; (N, N-dimethylamino) ethyl methacrylate, (N, N-dibenzylamino) ethyl methacrylate,
Substituted amino alcohol esters of unsaturated acids such as (N, N-dimethylamino) methyl methacrylate and (N, N-dimethylamino) propyl methacrylate; ethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate , Polyfunctional compounds such as 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, and diethylene glycol dimethacrylate, and / or molecules A polythiol compound having two or more thiol groups therein, such as trimethylolpropane trithioglycolate, trimethylolpropane trithio Ropioneto include a mixture of pentaerythritol thioglycolate and the like.

There is no particular limitation on the composition ratio of the mixture in the resin composition, and the mixture can be arbitrarily mixed and used,
In order to provide ordinary coating suitability, it is preferable that the prepolymer or oligomer is 5% by weight or more and the monomer and / or polythiol is 95% by weight or less.

The above components are the main components of the radiation-curable composition used in the present invention, and other organic solvents for adjusting viscosity and flexibility of the slip layer to be formed unless the transparency of the slip layer to be formed is disturbed. It is needless to say that various compatible non-reactive polymers for adjusting the properties and hardness, various fillers that do not impair transparency, or a polymerization inhibitor for improving storage stability can be optionally included. Is.

Such a radiation-curable coating composition can be cured by any radiation. For example, when an electron beam or gamma ray is used as the radiation, the radiation dose is preferably in the range of 1 to 20 Mrad. .

Further, as the radiation, when ultraviolet rays are adopted, in the above coating composition, further sensitizers, for example, benzophenone such as benzophenone and Michler's ketone, benzoin, benzoins such as benzoin alkyl ether, halogenated acetophenones, It is preferable to add an appropriate amount of a compound that generates a free radical by ultraviolet rays such as biacetyls.

The transparent sheet material for reel type cassette tape of the present invention is formed from the above-mentioned materials, and a preferred embodiment of the applicable sheet material of the present invention will be specifically described with reference to the accompanying drawings. Figures and 2 are schematic illustrations of a cross section of a preferred embodiment transparent slip sheet material of the present invention, and Figure 3 is a schematic illustration of a cross section of another preferred embodiment transparent slip sheet material. FIG. 4 is a schematic, cross-sectional view of yet another preferred embodiment transparent slip sheet material.

The embodiment shown in FIG. 1 has a slip layer 2a containing an antistatic agent on at least one surface of a base sheet material 1.
Is formed.

The embodiment shown in FIG. 2 is one in which a slip layer 2b containing both an antistatic agent and a lubricant is formed on at least one surface of a base sheet material 1, and the embodiment shown in FIG. Then, the slip layer formed on at least one surface of the base sheet material 1 has a two-layer structure, and the first layer 2a
Is a radiation curable resin layer containing an antistatic agent, and a layer made of a lubricant is formed thereon as the second layer 2c. This layer 2c may be formed as a radiation curable resin layer containing a lubricant. .

Another embodiment shown in FIG. 4 is the transparent sheet material 3 of the above-mentioned embodiment, which is further embossed.

The method itself for forming the transparent sheet material for reel type cassette tape of the embodiment shown in FIG. 1 and FIG. 2 may be a known method. For example, in the case of FIG. At a ratio of the above-mentioned radiation-curable coating composition to form a coating for forming a slip layer, and the coating is applied to the base by a coating method such as a roll coating method, a gravure coating method, a screen coating method, a fountain coating method. It is obtained by coating at least one surface of the sheet material, then drying the solvent if necessary, and then curing by a curing method as described above to form a slip layer.

The thickness of the slip layer thus formed is preferably such that the solid coating amount is about 0.1 to 4 g / m ² .

Further, in order to form the transparent sheet material of the embodiment illustrated in FIG. 3, a coating composition for forming an antistatic agent layer containing a predetermined amount of an antistatic agent and a slip layer forming containing a lubricant are formed as described above. Coating compositions are prepared separately, first a coating composition containing an antistatic agent is coated and cured on at least one side of the base sheet material as before, and then the surface of this antistatic agent layer is coated. Similarly, it is obtained by forming a slip layer.

In such an embodiment, the antistatic agent layer a preferably has a thickness such that the solid component coating amount is about 0.1 to 4 g / m ^2, and the lubricant layer b has a solid component coating amount of about 0.1 to 4 g / m ^2. A thickness of ² g / m ² is preferred.

In the above embodiments, the slip layer is provided on one surface of the base sheet material, but the present invention is not limited to these embodiments. For example, although not shown, the slip layer may be formed of the base sheet material. It may be provided on both sides, or may be provided with a slip layer having a two-layer structure on one surface and an antistatic agent layer on the other surface.

The embodiment shown in FIG. 4 shows an embodiment in which the transparent sheet material for reel type cassette tape of the present invention as shown in FIGS. 1 to 3 is embossed, and such embossing is conventionally known. Can be easily applied by an embossing roll or the like.

In this embodiment, both sides of the sheet material are embossed, but when forming the slip layer, glass beads or resin beads of an appropriate size that does not impair transparency are added to the coating liquid. By forming the slip layer, it is possible to emboss only the slip layer. By performing such embossing, it is possible to reduce the contact area between the slip sheet and the magnetic tape or reel, further reduce the friction when the magnetic tape is running, and reduce the amount of static electricity generated by the friction.

(Operation / Effect) According to the present invention as described above, the base sheet material constituting the transparent sheet material for reel type cassette tape of the present invention is transparent, and the slip layer formed on at least one surface thereof is also transparent. Therefore, the entire sheet is transparent. Therefore, the cassette half is useful as a sheet for a reel type cassette ape, which is transparent.

Further, the slip layer of the transparent sheet material for reel type cassette tape of the present invention is formed of a radiation curable resin layer containing an antistatic agent and / or a lubricant, and this radiation curable resin layer is a general normal dry type. Alternatively, unlike a resin layer made of a thermosetting paint, since it is a resin layer having extremely toughness and abrasion resistance, the antistatic agent and / or the lubricant contained therein is not mixed with the tape or reel. Since the sheet does not fall off from the resin layer due to contact, the sheet can maintain excellent antistatic property and surface smoothness for a long period of time.

In particular, when a bifunctional or higher functional monomer, oligomer or prepolymer is used as the radiation-curable resin in the present invention, the radiation-curable resin layer formed is formed from a cured resin having a network structure with a high crosslinking density. The above effects are further improved.

Further, by adopting, as the antistatic agent, a polymerizable antistatic agent having a tertiary amine or a quaternary ammonium group that can be copolymerized with a radiation-curable monomer, oligomer or prepolymer, these antistatic agents can be prevented. Since the agent is integrated with the radiation-curable resin that forms the slip layer, the antistatic agent does not bleed out or fall off during use, and exhibits a superior long-term stable antistatic property. Is.

Next, the present invention will be described more specifically with reference to examples.
In the text, "part" or "%" is based on weight unless otherwise specified.

Example 1 ST-3600 (Antistatic agent: Mitsubishi Yuka Fine Co., Ltd.) 50 parts Trimethylolpropane triacrylate 50 parts KP-301 (Silicone oil: Shin-Etsu Scientific Co., Ltd.) 1 part Isopropyl alcohol 50 parts Methanol 50 parts The above composition The coating liquid of is used with a gravure plate with a plate depth of 40 μm.
It is applied to a corona discharge treated polyester film with a thickness of 50 μm so that the solid coating amount is 0.3 g / m ³ , the solvent is dried, and the electron beam accelerated to 175 kV in a nitrogen gas atmosphere is 3 Mrad. It was irradiated and cured to form a slip layer, and the transparent sheet material for reel type cassette tape of the present invention was obtained.

The static half-life of the obtained transparent base sheet material is
It was less than 30 seconds.

Here, the static half-life is 1,00 when the sample is fixed on a rotating disk.
Rotate at 0 rpm, apply a voltage of 5 kV, and charge the sample for 30 seconds by corona discharge.
It was obtained by measuring in an atmosphere of 50% RH.

The measuring machine is a model of Kawaguchi Electric Works.
A SP-428 Electrostatic Paper Analyzer was used.

Then, the above sheet material is cut into a predetermined size and shape, and is interposed between the magnetic tape and the cassette half,
When it was used as a transparent sheet material and subjected to a durability test of 400 cycles of reproduction and rewinding, it exhibited an excellent antistatic effect, and did not cause problems such as dust adhesion to the magnetic tape and disordered winding of the tape.

Example 2 The same transparent sheet material as in Example 1 was embossed on both sides with a heating embossing roll, cut into a predetermined size and shape, and used as a transparent sheet for a reel type cassette tape. A durability test was conducted under the same conditions as in Example 1. As a result, the transparency was good, the surface activity was excellent, and no dust adhered to the tape or disordered winding of the tape occurred.

Example 3 The following composition was placed in a reaction vessel capable of heating and stirring,
The polymer was obtained by refluxing for 10 hours.

Methyl methacrylate 200 parts Dimethylaminoethyl acrylate 910 parts 2-Hydroxyethyl methacrylate 260 parts α, α′-azobisisobutyronitrile 5 parts Ethyl acetate 4,100 parts Then, 1 part by weight of benzoquinone is added to stop the reaction, With 640 parts of 2-hydroxyethyl methacrylate
A 1 mol to 1 mol adduct of 2,4-triene diisocyanate was added, 50 parts of dibutyltin dilaurate was further added, and the mixture was reacted at 80 ° C. for 5 hours while sending dry air.

Next, methyl ethyl ketone 1,000 parts, allyl chloride 4
50 parts and 1,200 parts of methyl alcohol were added and reacted at 80 ° C. for 4 hours. After cooling the reaction solution to room temperature, 200 parts of an ultraviolet sensitizer (Irgacure 184, manufactured by Ciba Geigy) was added to obtain an ultraviolet curable coating material.

This was applied to a corona-discharge-treated polyester film (thickness 38 μm) by gravure coating to obtain a solid content of 1 g / m ³
Was applied, the solvent was dried, and the resin was cured by passing it under a nitrogen gas atmosphere under an ultraviolet lamp having an output of 80 kW / cm under 10 cm at a running speed of 10 m / min to form a transparent resin layer.

Then, on this resin layer, an anti-blocking agent, Lubron LD-100 (manufactured by Daikin Industries, Ltd.) as a lubricant was diluted with toluene and a dry coating amount of 0.5 g was obtained by a roll coating method.
It was applied so as to be / m ³ and the solvent was removed to form a lubricant layer to obtain a transparent sheet material for reel type cassette tape of the present invention.

The static half-life of this transparent base sheet material was 60 seconds or less.

Further, both sides of the above slip sheet material were processed using heated embossing rolls, cut into a predetermined size and shape, and used as a transparent sheet material for reel type cassette tape, and the same durability test as in Example 1 As a result, the transparency was good, the surface slipperiness was excellent, and no dust adhesion to the tape or disordered winding of the tape occurred.

[Brief description of drawings]

1 and 2 are schematic illustrations of a cross section of a transparent slip sheet material of a preferred embodiment of the present invention, and FIG. 3 illustrates a cross section of a transparent slip sheet material of another preferred embodiment. FIG. 4 is a schematic representation of a cross-section of yet another preferred embodiment transparent slip sheet material. FIG. 5 is a perspective view of the reel type cassette tape described in the present invention. 1; base sheet material 2; slip layer 2a; antistatic agent layer 2b; layer containing antistatic agent and lubricant 2c; lubricant layer 3; embossed transparent sheet material 4; reel type cassette tape 5; reel 6 Transparent sheet 7 Metal flange 8 Cassette half 9 Screw 10 Hub 11 Cleaning leader tape 12 Magnetic tape

Claims (4)

[Claims] 1. A transparent base sheet material, and a slip layer provided on at least one surface of the base sheet material, the slip layer comprising a prepolymer having at least one ethylenically unsaturated bond in a molecule, After applying a curable composition containing an oligomer or a monomer as a main component, and a coating liquid containing an antistatic agent on a base sheet material,
A transparent sheet material for reel-type cassette tapes, characterized by being cured by irradiation with radiation. 2. A transparent sheet material for a reel type cassette tape according to claim 1, wherein the slip layer contains an antistatic agent and a lubricant. 3. The reel type cassette according to claim 1, wherein the slip layer has a two-layer structure, the first layer in contact with the base sheet material contains an antistatic agent, and the second layer is a lubricant. Transparent sheet material for tape. 4. The transparent sheet material for reel-type cassette tape according to claim 1, wherein at least one surface is embossed.