JPH08161852A - Production of floppy disk - Google Patents

Abstract

PURPOSE: To produce a magnetic disk for floppy disks. CONSTITUTION: The magnetic disk for floppy disks is produced by using a double coated tape having a thermosensitive tacky adhesive layer contg. a solid plasticizer, thermoplastic resin and tackifier on one surface of a base material and a pressure sensitive adhesive layer on another surface for adhesion of a center core and a magnetic sheet. Unnecessary objects, such as separators, are fewer than a conventional method of using the double coated tape. Since the pressure sensitive adhesive is applied only on one surface, the accuracy of blanking is high. The floppy disk having the durability equiv. to or better than the durability of commercially marked floppy disks, etc., is thus obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is non-tacky at room temperature but develops tackiness upon heating, and
A magnetic disk for a floppy disk can be formed by using a double-sided tape having a heat-sensitive adhesive layer whose adhesiveness is maintained for one time even after removing the heating source, and a pressure-sensitive adhesive layer on one side. The present invention relates to a manufacturing method.

[0002]

Floppy disk as a recording medium,
For example, the 3.5-inch MFD has a rotatable magnetic disk in a hard case, and the magnetic disk is mainly made of metal (in recent years, made of plastic such as resin) in order to improve chucking accuracy. There is also a center core). Conventionally, a magnetic disk is manufactured by adhering a magnetic sheet to a center core.After manufacturing, a magnetic disk that is determined to be defective due to misalignment or other causes, unless the center core is defective, After peeling the magnetic sheet from the core, the center core is collected and reused.

When manufacturing a magnetic disk, a double-sided tape is mainly used as an adhesive for adhering a magnetic sheet to a center core. When the double-sided tape is used, it can be easily peeled off by peeling the double-sided tape. , The center core can be reused. The double-sided tape is also called a double-sided adhesive tape or a double-sided adhesive tape, and as shown in FIG. 1, a tape body having pressure-sensitive adhesive layers 2 on both surfaces of a base material 3 and a single separator 1 ( (Also referred to as a liner or release liner), or as shown in FIG. 2, it comprises a tape body having pressure-sensitive adhesive layers 5 on both sides of a base material 6 and two separators 4 for protecting its adhesiveness. In general, the tape body is often wound in a roll shape together with the separator, and it can be processed into various forms such as a flat sheet shape such as a sheet or film having an appropriate size depending on the application. .

The separator is necessary to protect the surface of the pressure-sensitive adhesive layer, and is a release paper obtained by releasing the surface of paper such as high-quality paper or glassine paper with silicone resin or the like, or release of silicone resin or the like. Usually, a plastic film coated with a mold agent or a plastic film alone is often used. However, in order to perform mold release processing on both sides, it is usually punched to form the desired shape (for example, ring shape). In doing so, there was a problem that the pressure-sensitive adhesive layer and the release paper slip and cause a shift. Furthermore, since it has pressure-sensitive adhesive layers on both sides of the substrate, the pressure-sensitive adhesive adheres to the punching blade during punching,
Blade fouling is likely to occur, and moreover, a pressure sensitive adhesive adheres to the cut surface.

When a magnetic disk is manufactured, a double-sided tape is punched out into a ring shape to bond the center core and the magnetic sheet, but there is a problem in the punching precision due to blade contamination. there were. In order to solve this problem, devise a release agent for the separator,
Attempts have also been made to produce a non-slip separator, but due to the relationship between the release agent and the pressure-sensitive adhesive, a special release agent was required, and there were problems in terms of cost and the like. Also,
In order to prevent the blade from being soiled and attached by the pressure-sensitive adhesive layer, methods such as thinning the pressure-sensitive adhesive layer have been devised, but there are problems such as limited countermeasures from the viewpoint of adhesive performance. there were.

In recent years, a method of bonding a magnetic sheet to a center core by using a hot melt adhesive instead of the double-sided tape has been devised, which can be manufactured at low cost.
The hot melt adhesive has a short open time (usable time as an adhesive), and when the magnetic sheet is bonded to the center core, if it is judged to be defective due to misalignment or other reasons, the magnetic Although it is easy to peel off the sheet from the center core, there is a problem that it is difficult to remove the hot melt adhesive from the center core.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to have a heat-sensitive adhesive layer containing a solid plasticizer, a thermoplastic resin and a tackifier on one side of a substrate, and further pressure-sensitive adhesive on one side. It is an object of the present invention to provide a method for manufacturing a magnetic disk for a floppy disk using a double-sided tape having an agent layer.

[0008]

That is, according to the present invention, when a magnetic disk for a floppy disk is manufactured, a method for adhering a magnetic sheet to a center core includes a solid plasticizer, a thermoplastic resin and an adhesive on one side of a substrate. Provided is a method of using a double-sided tape having a heat-sensitive adhesive layer containing an imparting agent and having a pressure-sensitive adhesive layer on one side. As shown in FIG. 3, the double-sided tape used in the present invention is composed of a separator 7, a pressure-sensitive adhesive layer 8, a substrate 9 and a heat-sensitive adhesive layer 10. Usually, the mold release treatment of the separator is performed on one surface in contact with the pressure-sensitive adhesive layer 8.

As the substrate, paper, non-woven fabric, woven fabric, film, foam or the like which has been used as a substrate for conventional double-sided adhesive tape or double-sided adhesive tape can be used. Examples of the paper include papers such as Japanese paper, high-quality paper and glassine paper, and examples of the non-woven fabric include non-woven fabric such as rayon, polyester and polypropylene. Examples of the woven cloth include woven cloth of natural fibers or synthetic fibers such as cotton cloth, suf, and vinylon, and examples of the film include films of polyester (especially polyethylene terephthalate), polyvinyl chloride, polypropylene, cellophane and the like. Examples of the foam include polyurethane, polyethylene, butyl rubber, chloroprene, vinyl chloride, and acrylic rubber. For the floppy disk, which is the object of the present invention, a film or the like is used for accurate adhesion. It is preferable that the substrate itself is thin.

As the pressure-sensitive adhesive, commonly used rubber-based, acrylic-based, vinyl-based, silicon-based, etc. are used. For example, "Adhesion Handbook" (Second Edition, Showa 55)
Yearly, published by Nikkan Kogyo Shimbun) can be used. As the basic skeleton, an elastic main resin,
It is a tackifier, a plasticizer and other fillers and additives. Examples of the main resin of the pressure-sensitive adhesive include natural rubber, synthetic isoprene rubber, recycled rubber, acrylic acid ester, styrene-acrylic acid ester, styrene-butadiene, ethylene-vinyl acetate, vinyl acetate, vinyl acetate-acrylic acid ester. Polymers such as ethylene-vinyl chloride, ethylene-acrylic acid ester, ethylene-acrylic acid, butadiene, urethane, styrene-isoprene, acrylonitrile-butadiene, isobutylene, and vinyl ether.

Examples of tackifiers for pressure-sensitive adhesives include terpene resins, aliphatic petroleum resins, aromatic petroleum resins, coumarone-indene resins, styrene resins, phenol resins, terpene-phenol resins, rosin derivatives ( Examples thereof include rosin, polymerized rosin, hydrogenated rosin, esters thereof with glycerin and pentaerythritol, and resin acid dimer). As the plasticizer for the pressure-sensitive adhesive, a plasticizer that is liquid at room temperature is mainly used, and examples thereof include mineral oil, lanolin, liquid polybutene, and liquid polyacrylate.

To the pressure-sensitive adhesive, other fillers and additives can be added. The main resin of the pressure sensitive adhesive,
Tackifier, plasticizer and other fillers, additives are 1
It can be used in one kind or a mixture of two or more kinds. The pressure sensitive adhesive is an aqueous emulsion type, a water soluble type,
It can be coated on the substrate as a hot melt type, a solventless type or an organic solvent type. The heat-sensitive adhesive has a solid skeleton, a thermoplastic resin, and a tackifier as a basic skeleton. For example, those described in "Adhesion Handbook" (12th edition, 1980, published by Kobunshi Kogyokai) Can be used. Thermoplastic resins are the source of adhesive strength and adhesive strength. Further, since the solid plasticizer is solid at room temperature, it does not impart plasticity to the resin, and it melts by heating to swell or soften the resin. Acts to express. On this occasion,
When the tackifier is present, the tackiness appears more remarkably,
Practical characteristics are improved.

Examples of solid plasticizers for heat-sensitive adhesives include diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate, dihydroabietyl phthalate, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate, tribenzoic acid. Trimethylolethane,
Tribenzoic acid glyceride, tetrabenzoic acid pentaerythritol, sucrose octaacetate, tricyclohexyl citrate,
Examples thereof include N-cyclohexyl-p-toluenesulfonamide, and dicyclohexyl phthalate is preferable. Further, the thermoplastic resin of the heat-sensitive adhesive is preferably used in a solid content ratio of 20 to 200 parts by weight, and further 30 to 140 parts by weight with respect to 100 parts by weight of the solid plasticizer. Examples of the thermoplastic resin include acrylic acid ester, styrene-acrylic acid ester, styrene-butadiene, ethylene-vinyl acetate, vinyl acetate, vinyl acetate-acrylic acid ester,
Ethylene-vinyl chloride, ethylene-acrylic acid ester, ethylene-acrylic acid, butadiene, urethane, styrene-isoprene, isoprene, acrylonitrile-
Examples thereof include polymers such as butadiene, isobutylene, and vinyl ether.

Further, the tackifier for improving the tack performance of the heat-sensitive adhesive is 5 to 10 with respect to 100 parts by weight of the solid plasticizer.
It is preferably used in a solid content ratio of 0 part by weight, more preferably 10 to 50 parts by weight. Examples of the tackifier include terpene resin, aliphatic petroleum resin, aromatic petroleum resin, coumarone-
Examples thereof include indene resin, styrene resin, phenol resin, terpene-phenol resin, and rosin derivative (rosin, polymerized rosin, hydrogenated rosin and their glycerin, esters with pentaerythritol, resin acid dimer, etc.). The solid plasticizer, thermoplastic resin or tackifier of the heat-sensitive adhesive may be used alone or in a mixture of two or more.

That is, the solid plasticizer of the heat-sensitive adhesive is
Dicyclohexyl phthalate and diphenyl phthalate,
Dicyclohexyl phthalate and dihexyl phthalate,
Dicyclohexyl phthalate and dihydroabietyl phthalate, Dicyclohexyl phthalate and dimethyl isophthalate, Dicyclohexyl phthalate and sucrose benzoate, Dicyclohexyl phthalate and Ethylene glycol dibenzoate, Dicyclohexyl phthalate and Trimethylolethane tribenzoate, Dicyclohexyl phthalate And tribenzoic acid glyceride, dicyclohexyl phthalate and pentaerythritol tetrabenzoate, dicyclohexyl phthalate and sucrose octaacetate, dicyclohexyl phthalate and tricyclohexyl citrate,
Dicyclohexyl phthalate and N-cyclohexyl-p-
It is also possible to use two kinds with toluenesulfonamide or the like or a mixture of three kinds or more with dicyclohexyl phthalate, diphenyl phthalate and dihexyl phthalate and the like.

The tackifier for the heat-sensitive adhesive is a terpene resin and an aliphatic petroleum resin, an aromatic petroleum resin and a coumarone-indene resin, a styrene resin and a phenol resin, a terpene-phenol resin and a rosin derivative. Two types of terpene resin and rosin derivative, aliphatic petroleum resin and rosin derivative, aromatic petroleum resin and rosin derivative, coumarone-indene resin and rosin derivative, styrene resin and rosin derivative, phenol resin and rosin derivative 3 with rosin derivatives, aliphatic petroleum resins and aromatic petroleum resins
It can also be used in a mixture of types or more.

Thermoplastic resins for heat-sensitive adhesives include acrylic acid esters and styrene-acrylic acid esters, styrene-butadiene and ethylene-vinyl acetate, vinyl acetate and vinyl acetate-acrylic acid esters, ethylene-vinyl chloride and ethylene. -Acrylic acid esters, ethylene-acrylic acid and butadiene, urethane and styrene-isoprene, styrene-butadiene and acrylic acid esters, styrene-butadiene and styrene-acrylic acid esters, styrene-butadiene and vinyl acetate, styrene-butadiene and vinyl acetate- Acrylic ester, styrene-butadiene and ethylene-vinyl chloride, styrene-butadiene and ethylene-acrylic ester, styrene-butadiene and ethylene- Acrylic acid, styrene - butadiene and butadiene, styrene - butadiene and urethane, styrene - butadiene and styrene - isoprene, styrene - butadiene and acrylonitrile -
It is also possible to use two kinds of butadiene or the like or a mixture of three kinds or more of styrene-acrylic acid ester, styrene-butadiene, ethylene-vinyl acetate and the like.

The heat-sensitive adhesive can be coated on the substrate as an aqueous emulsion or an organic solvent solution.
Considering the handling of the tape after coating and drying, it is preferable to coat it as an aqueous emulsion. Other fillers and the like may be added to the pressure-sensitive adhesive and the heat-sensitive adhesive. As the filler and the like, for example,
Inorganic substances such as zinc oxide, calcium carbonate, clay, aluminum hydroxide, titanium oxide, alumina, kaolin, talc, colloidal silica and alumina sol, paraffin,
Examples thereof include natural waxes, synthetic waxes, natural fats and oils, organic substances such as antioxidants, and resin powders. Further, a solvent, a liquid plasticizer, etc. may be added for the purpose of improving the film-forming property of the coating film. Further, if necessary, a dispersant, a defoaming agent, a thickener, etc. can be used.

The double-sided tape of the present invention is generally prepared by applying a heat-sensitive adhesive to one surface of a substrate and a pressure-sensitive adhesive to one surface of the substrate, and then (when applied as an aqueous emulsion or water-soluble). After drying, or when coated as an organic solvent solution (only the heat-sensitive adhesive), after release of the tackiness by drying), a separator (usually one side in contact with the pressure-sensitive adhesive layer is subjected to a release treatment). However, it can be processed into various forms such as a flat sheet or a sheet or a film having an appropriate size depending on the intended use. In the present invention, a magnetic disk for a floppy disk is manufactured with the structure shown in FIG. That is, for adhering the magnetic sheet 11 to the center core 12, a thermosensitive adhesive layer containing a solid plasticizer, a thermoplastic resin and a tackifier is provided on one side, and the pressure sensitive adhesive is provided on one side. The double-sided tape 13 with layers is used to produce a magnetic disk for a floppy disk.

When the center core of the present invention and the magnetic sheet are adhered to each other, a heat-sensitive adhesive layer containing a solid plasticizer, a thermoplastic resin and a tackifier is provided on one surface of the substrate, and one surface is provided with the heat-sensitive adhesive layer. The method of using the double-sided tape having the pressure-sensitive adhesive layer can be applied to the adhesion between the optical disk substrate or the magneto-optical disk substrate and the hub.

[0021]

[Examples 1 to 10]

(Pressure Sensitive Adhesive) Main components and curing agents of the pressure sensitive adhesive manufactured by Toyo Ink Mfg. Co., Ltd. shown in Tables 1 and 2 were mixed with a stirrer to prepare a coated sample.

(Thermal Sensitive Adhesive) According to the formulations shown in Tables 1 and 2,
First, put the solid plasticizer, maleic acid resin solution and water in the ball mill, crush for 24 hours, then add the thermoplastic resin emulsion, tackifier emulsion and additives,
Mixing and stirring were performed in a mixer for 5 minutes to prepare a heat-sensitive adhesive. The pressure-sensitive adhesive obtained was coated on one side of a polyester film at a coating amount of 40 g / m ² at 100 ° C.
After drying for 2 minutes, place a separator on the coated surface, and further apply a heat-sensitive adhesive on one side so that the coating amount is 30 g / m ² and dry at 40 ° C for 5 minutes, double-sided tape Got
No adhesiveness was confirmed in the heat-sensitive adhesive layer after drying.

The obtained double-sided tape was kept at 25 ° C. and 60% for 7 days.
After being left standing (aged) in the room, the cutting property test (test method is shown below) was performed, and the results are shown in Tables 1-2.
Further, the obtained double-sided tape was cut into a ring shape, and the center core 12 and the magnetic sheet 11 were adhered by the following two methods as shown in FIG. Cutability test: The double-sided tapes of the examples and comparative examples were laminated with 100 pieces of samples cut to a width of 10 cm and a length of 10 cm without heating, the edges were cut off using a guillotine cutter, and pressure-sensitive adhesion of the cut surfaces The sticking-out state of the pressure-sensitive adhesive or the heat-sensitive adhesive to the blade of the cutter was observed by squeezing out the agent or the heat-sensitive adhesive, and judged according to the following criteria.

(Protrusion of Pressure-sensitive Adhesive or Heat-sensitive Adhesive to Cut Surface of Sample) ◎ ・ ・ ・ ・ ・ ・ No protrusion. The stacked samples are separated. ○ ・ ・ ・ ・ ・ ・ There is almost no protrusion. The stacked samples are separated. △: ・ Extrusion is observed, but the stacked samples are scattered. ×: ・ Overhanging is considerably observed, and the overlapped samples do not come apart.

(Attached state of pressure-sensitive adhesive or heat-sensitive adhesive on blade of guillotine cutter) ⋅⋅ ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙. ○: ・ The blade of the cutter becomes cloudy or some sticking is observed, but when the blade is touched with the hand, almost no tackiness is observed (there is almost no tackiness). X: Adhesion is recognized, and tackiness is recognized when the blade is touched by hand (tackiness is felt).

Method of adhering the center core and the magnetic sheet: 1) After cutting the double-sided tape in a ring shape, the separator protecting the pressure-sensitive adhesive layer is peeled off and attached to the center core. Then, heat to 120 ℃ for 30 seconds,
The adhesiveness of the heat-sensitive adhesive layer is developed, and the center core and the magnetic sheet are adhered to each other as shown in FIG. 2) After cutting the double-sided tape into a ring, 120
By heating at 30 ° C. for 30 seconds to develop the adhesiveness of the heat-sensitive adhesive layer, the center core and the magnetic sheet are bonded together as shown in FIG.

Further, a magnetic disk having a center core and a magnetic sheet adhered was housed in a hard case to prepare a 3.5 inch MFD floppy disk. This floppy disk was tested for weather resistance according to JIS X-6223,
The modulation of the innermost track before and after the test (value (percentage) obtained by dividing the difference between the maximum value and the minimum value in the output waveform of the floppy disk by the sum) was measured, and the results were judged according to the following criteria. It shows in Tables 1-2. ◎ ・ ・ ・ less than 5% ○ ・ ・ ・ ・ ・ ・ 5% or more, less than 10% × ・ ・ ・ ・ ・ ・ 10% or more [Comparative Examples 1 to 3] Implementation of commercially available floppy disks In the same manner as in the example, the modulation was measured, and the judgment was made according to the following criteria, and the results are shown in Table 3.

From the results shown in Tables 1 to 3, there is a heat-sensitive adhesive layer containing a solid plasticizer, a thermoplastic resin and a tackifier on one side of the substrate, and the pressure-sensitive adhesive layer is on one side. It is shown that the floppy disk manufactured by adhering the center core and the magnetic sheet using the double-sided tape having No. 3 is comparable to the commercially available floppy disk.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

* 1 Solid content ratio in solution to total amount * 2 Styrene-butadiene copolymer * 3 Ethylene-vinyl acetate copolymer * 4 Toyo Ink Mfg. Co., Ltd. pressure sensitive adhesive base,
Product name Olivine BPS1109 * 5 Pressure-sensitive adhesive curing agent manufactured by Toyo Ink Manufacturing Co., Ltd. Product name Olivine BHS8515 * 6 Pressure-sensitive adhesive base compound manufactured by Toyo Ink Manufacturing Co., Ltd.
Product name Olivine BPS4089 * 7 Pressure sensitive adhesive hardener manufactured by Toyo Ink Mfg. Co., Ltd. Product name Olivine BPS4089B * 8 Pressure sensitive adhesive base compound manufactured by Toyo Ink Mfg. Co., Ltd.
Brand name Olivine BPS8404 * 9 Pressure sensitive adhesive curing agent manufactured by Toyo Ink Mfg. Co., Ltd., Brand name Olivine BHS8404B * 10 Mixing ratio (parts by weight) of the curing agent to 100 parts by weight of the main agent in the pressure sensitive adhesive.

* 11 In the adhesion of the center core and the magnetic sheet, the separator protecting the pressure-sensitive adhesive layer of the double-sided tape cut in a ring shape is peeled off,
After sticking to the center core, it is heated to 120 ° C. for 30 seconds to develop the tackiness of the heat-sensitive adhesive layer, and the center core and the magnetic sheet are bonded. * 12 When bonding the center core and magnetic sheet,
After cutting the double-sided tape into a ring,
It is heated for 30 seconds to develop the tackiness of the heat-sensitive adhesive layer, the separator is peeled off, and the center core and the magnetic sheet are adhered.

* 13 3.5-inch floppy disk manufactured by Hitachi Maxell Co., Ltd., product name MF2-256HD * 14 3.5-inch floppy disk manufactured by Fuji Photo Film Co., Ltd., product name MF2HD DOS8 * 15 3.5-inch floppy disk manufactured by TDK Corporation, product name MF-2HD256

[0035]

EFFECT OF THE INVENTION A solid plasticizer is provided on one side of the substrate of the present invention.
Floppy having a heat-sensitive adhesive layer containing a thermoplastic resin and a tackifier, and using a double-sided tape having a pressure-sensitive adhesive layer on one side, a center core and a magnetic sheet are adhered to each other. The disc manufacturing method is less unnecessary than a conventional double-sided tape method, such as a separator, and is coated with a pressure-sensitive adhesive only on one side, so that the cutting property is also good, that is, It was shown that the punching accuracy was high and the durability required for floppy disks was comparable to that of commercially available floppy disks. Since the demand for floppy disks is quite large, its industrial significance is extremely great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conventional double-sided tape having one separator.

FIG. 2 is a cross-sectional view of a conventional double-sided tape having two separators.

FIG. 3 is a cross-sectional view of a double-sided tape used in the present invention.

FIG. 4 is a perspective view of a magnetic disk for a floppy disk.

[Explanation of symbols]

1 Separator 2 Adhesive layer 3
Base material 4 Separator 5 Adhesive layer 6
Substrate 7 Separator 8 Pressure-sensitive adhesive layer 9
Base material 10 Heat-sensitive adhesive layer 11 Magnetic sheet 1
2 Center core 13 The double-sided tape shown in Fig. 3 in a ring shape.

Claims (1)

[Claims] 1. When fixing a center core and a magnetic sheet, a heat-sensitive adhesive layer containing a solid plasticizer, a thermoplastic resin and a tackifier is provided on one surface of a substrate, and pressure sensitive on one surface. A method for manufacturing a magnetic disk for a floppy disk, which comprises using a double-sided tape having an adhesive layer.