JPH09188950A - Binder for nonwoven fabric, nonwoven fabric for floppy disk cleaner, its production and floppy disc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonwoven fabric for a floppy disk cleaner preventing problems such as flaw on the surface of a disc and reduction in reproduction output caused by adhesion of lint and dust before it happens by coating a web with a foamy binder having a specific composition to bind fibers and coating the surface of the fibers. SOLUTION: An aqueous emulsion of a polymer such as an acrylic acid ester is mixed with an alkyl sulfate alkanolamine salt such as lauryl sulfate triethanolamine to give a binder for a nonwoven fabric. The binder is made foamy by a hand mixer, applied to a web having 30-50g/m<2> weight, which is dried and heat-treated to bond fibers constituting the web and to coat the surface of the rayon fibers to provide a nonwoven fabric for a floppy disk cleaner free from occurrence of lint during ultrasonic welding processing. A floppy disc is produced by using the nonwoven fabric.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder for a nonwoven fabric, a nonwoven fabric for a floppy disk liner, and a method for producing the same, and more specifically, it does not generate dust and scratches or wear on the floppy disk surface. The present invention relates to a binder for non-woven fabrics, a non-woven fabric for floppy disk liners, and a method for producing the same. The present invention also relates to a floppy disk using such a nonwoven fabric for a floppy disk liner.

[0002]

2. Description of the Related Art Conventionally, when a general non-woven fabric is used as a liner for a floppy disk, fibers, binders, etc. fall off from the non-woven fabric during the production and use of the floppy disk to generate fiber waste (lint). Attached to the surface of the floppy disk or scratched the surface, causing a disk error.

As a particularly prominent example, a heat emboss type liner, which is very often used in 3.5-inch floppy disk cartridges, is ultrasonic welded when installing the liner or ultrasonic weld when sealing the shell. As a result, there is a problem that lint, dust, or the like adhering to or in the liner drops onto the surface of the floppy disk and adheres to the surface of the floppy disk, or scratches the surface, causing a reduction in reproduction output.

Therefore, various methods have been proposed for suppressing the generation of lint, dust, and the like, which are problems of the heat embossing type liner, by using a binder. That is, by applying a binder to the nonwoven web, the surface of the fiber is covered to prevent dust from being generated from the nonwoven liner.

There are various methods for applying a binder to a nonwoven web, and one example thereof is foam coating (floss coating). Foam coating is known as a general foaming application method.

[0006]

However, when the binder is applied to the web of the non-woven fabric by foam coating, if only the binder is used, foamability,
Since the foam retention and foam hardness (foam stamina) are poor,
There is a drawback in that the binder cannot be uniformly applied to the inside of the web.

Particularly in recent years, development of a floppy disk has been focused on miniaturization, high density and high speed rotation, and development of a high performance liner capable of meeting these requirements is strongly desired.

Therefore, an object of the present invention is to provide a non-woven fabric binder which can be applied evenly to the inside of the non-woven web when performing foam coating on the non-woven web. It is another object of the present invention to provide a non-woven fabric for a floppy disk liner that does not generate dust and can prevent scratches and abrasion on the floppy disk surface and a method for manufacturing the same. A further object of the present invention is to provide a floppy disk using such a nonwoven fabric for a floppy disk liner.

[0009]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by incorporating a specific compound into a binder for a non-woven fabric, the foamability of the non-woven fabric binder in foam coating, the retention of the foam and the foam It has been found that the hardness can be remarkably improved.

The present invention has been made based on the above findings, and provides a non-woven fabric binder characterized by comprising (a) an aqueous emulsion; and (b) an alkyl sulfate. It has achieved its purpose.

Further, the present invention is characterized in that the fibers are bound together and the surface of the fibers is coated by a non-woven fabric binder comprising (a) an aqueous emulsion; and (b) an alkylsulfate; The above object has been achieved by providing a nonwoven fabric for use.

In the present invention, a nonwoven fabric binder comprising (a) an aqueous emulsion; and (b) an alkyl sulfate is foamed and then applied to a web to bond the fibers of the web together. The above object is achieved by providing a method for producing a non-woven fabric for a floppy disk liner, which comprises coating the fiber surface.

Further, the present invention achieves the above object by providing a floppy disk using the above-mentioned nonwoven fabric for a floppy disk liner.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the non-woven fabric binder of the present invention comprises an aqueous emulsion and an alkyl sulfate. The aqueous emulsion in the binder for a non-woven fabric is not particularly limited, and any one can be used as long as it can bond the fibers in the web and coat the surface of the fibers. For example, an aqueous emulsion of various polymers can be used, and examples of such polymers include styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NB
R), acrylonitrile-butadiene copolymer, ethylene-vinyl acetate (EVA), ethylene-vinyl chloride (E
VCL), polyvinyl chloride (PVC), acrylic acid ester, acrylic / acrylic copolymer, polyvinyl acetate (PVA), polyvinyl alcohol and copolyester. In the present invention, these aqueous emulsions may be used alone or in combination of two or more. Among these aqueous emulsions, it is particularly preferable to use an aqueous emulsion of styrene-butadiene rubber and acrylic acid ester from the viewpoints of adhesiveness between non-woven fabric fibers and prevention of scratches on the medium surface.

The above aqueous emulsion can be synthesized by a known emulsion polymerization method. That is, the monomer of the above polymer is added dropwise to an appropriate amount of water containing a small amount of an emulsifier and a polymerization initiator to emulsion-polymerize the monomer.

The emulsifier and the polymerization initiator are not particularly limited. As the emulsifier, for example, an anionic or nonionic emulsifier can be used or used in combination. As the polymerization initiator, generally, persulfates such as potassium persulfate and ammonium persulfate, peroxides such as hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide and the like should be used. However, water-soluble initiators are preferred.

In the emulsion polymerization, a chain transfer agent, n-dodecyl mercaptan, t-dodecyl mercaptan and the like, which are usually used in the emulsion polymerization, may be optionally used.

The proportion of solids in the aqueous emulsion thus obtained is generally from 2 to 50%, preferably from 5 to 30%, based on the weight of the aqueous emulsion.

The binder for nonwoven fabric of the present invention is obtained by mixing the aqueous emulsion obtained by the above emulsion polymerization with the above alkyl sulfate. The mixing ratio of the aqueous emulsion and the alkyl sulfate in the binder for a nonwoven fabric is not particularly limited, but preferably, the alkyl sulfate is added in an amount of 0.1 to 5% based on the solid content weight of the binder for a nonwoven fabric. , And more preferably 0.5 to 3%. If the amount of the alkyl sulfate added is less than 0.1%, no sufficient effect can be obtained on the foamability, and if the amount of the alkyl sulfate added is more than 5%, an effect corresponding to the added amount is obtained. Since it may not exist, it is preferable to set it within the above range. Further, the above aqueous emulsion is preferably added in an amount of 0.002 to 2.5% (solid content), more preferably 0.01 to 1.5% (solid content) based on the weight of the solid content of the binder for a nonwoven fabric.
Added.

Next, the alkyl sulfate will be described. The alkyl sulfate salt is a salt obtained by neutralizing alkyl sulfate with an alkali. As such an alkylsulfuric acid, a linear or branched alkylsulfuric acid having 5 to 20 carbon atoms can be generally used. The preferred alkyl group has 10 to 14 carbon atoms. Particularly preferred alkylsulfuric acid is
It is lauryl sulfate. In the present invention, only one type of the above alkyl sulfuric acid may be used, or two or more types may be used in combination.

The above-mentioned salt is not particularly limited, and examples thereof include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as magnesium salt and calcium salt,
Ammonium salts, amine salts and the like can be used. Particularly, in the present invention, it is preferable to use an amine salt, and more preferable to use an alkanolamine salt from the viewpoints of foamability and foam retention. Examples of the alkanolamine include monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine and the like. Of these, it is particularly preferable to use triethanolamine from the viewpoint of foamability and foam retention. In the present invention,
Only one type of the above salts may be used, or two or more types may be used in combination.

Alkyl sulfates particularly preferably used in the present invention are lauryl sulfate, especially triethanolamine lauryl sulfate. However, the present invention is not limited to such alkylsulfates, and the alkylsulfates and the salts may be arbitrarily combined and used alone or in combination of two or more kinds.

If necessary, various additives such as nonionic surfactants such as polyoxyethylene nonylphenyl ether and anionic surfactants such as sodium dodecyl sulfate are added to the non-woven fabric binder thus obtained. Agents and the like can be added. The amount of these additives added is 0.05 to 1 based on the weight of the binder for nonwoven fabric.
0%. Further, if necessary, an antistatic agent, an antifungal agent or the like may be added.

Next, the nonwoven fabric for the floppy disk liner of the present invention will be described. The non-woven fabric for a floppy disk liner of the present invention is characterized by binding the fibers and coating the fiber surface with the above-mentioned non-woven fabric binder. The amount of the non-woven fabric binder used is 3 to 30% (solid content) based on the weight of the non-woven fabric.
Is preferable, and more preferably 5 to 18% (solid content). If the amount of the non-woven fabric binder used is less than 3%, the adhesive force between the fibers of the non-woven fabric may be small and it may not be possible to maintain the form of the liner. If it exceeds 30%, the cleaning effect may not be sufficient, In addition, scratches may be generated on the floppy disk surface due to friction and abrasion between the floppy disks of the binder, which may cause defective reproduction of the floppy disk.

The non-woven fabric for a floppy disk liner of the present invention can be produced by the method described below, but its basis weight is generally 30 to 50 g / m ² , and preferably 35 to 45 g / m ² . When the basis weight is less than 30 g / m ² , the effect as a floppy disk liner is reduced, the dust wiping action is reduced, and the floppy disk may be damaged. If the basis weight exceeds 50 g / m ² , the thickness and elasticity of the non-woven fabric increases, the rotational torque of the floppy disk increases, and smooth rotation of the floppy disk is impaired.

The fibers used for producing the non-woven fabric for a floppy disk liner of the present invention are not particularly limited, and conventionally known fibers can be used. For example,
Rayon, polyester, polyamide, polypropylene, polyethylene and the like can be used. Further, if necessary, core-sheath type fibers or side-by-side type fibers, which are composite fibers using two types of fibers having different melting points, can be used. These fibers may be used alone or in combination of two or more.

The fibers may be in the form of continuous filaments or staple fibers. When the above fibers are used in the form of staple fibers, it is generally preferable that the fiber length is 1.0 to 5.0 cm. When the fiber length is within this range, a web can be uniformly manufactured, the obtained nonwoven fabric has a good texture, and a sufficient dust wiping action is exhibited.

The fiber diameter of the above fibers is not particularly limited,
Generally, it is preferably 1.0 to 2.0 denier.
When the fiber diameter is within this range, a nonwoven web can be uniformly manufactured, the obtained nonwoven has a good texture, and a sufficient dust wiping action is more effectively exhibited.

Further, according to the present invention, there is provided a method for producing the non-woven fabric for the floppy disc liner. That is, the method for producing a non-woven fabric for a floppy disc liner of the present invention comprises forming the above-mentioned non-woven fabric binder into a foam, applying the web to the web, binding the fibers of the web and coating the fiber surface.

In order to produce a web, staple fibers are generally applied to a card machine to form a web, but the method is not limited to such a method, and other web forming methods such as the spunbond method, the meltblowing method and the spunlace method are used. Etc. may be used.

Next, the above-mentioned nonwoven fabric binder is applied to the obtained web. At this time, the binder is foamed and applied to the web (foam coating or floss coating). To make the non-woven fabric binder foamy, the non-woven fabric binder can be foamed with a mixer, a hand mixer or the like. After the web is impregnated with the foamed non-woven fabric binder, excess liquid is squeezed by a roll such as a mangle. When the non-woven fabric binder has a low foaming property when the non-woven fabric binder is foamed, an activator for improving the foamability may be added to the non-woven fabric binder, if necessary. The type and amount of the activator added are not particularly limited. Further, as another method of applying the binder for non-woven fabric to the web, there is a method of spraying the binder for non-woven fabric on the web.

After applying the non-woven fabric binder to the web, the water or organic solvent in the non-woven fabric binder is removed by drying, and the non-woven fabric binder is cured so that the fibers of the web are bonded and one of the fiber surfaces is bonded. A non-woven fabric is obtained which is partially or wholly coated with the above non-woven fabric binder. As a method for drying the web applied with the nonwoven fabric binder and curing the nonwoven fabric binder, hot air, hot rolls, infrared rays, microwaves, thermal calendering, etc. can be used, but are not limited to these methods. Not something. The temperature for curing the above-mentioned nonwoven fabric binder is generally in the range of 110 to 170 ° C.

After the above-mentioned non-woven fabric binder is cured to form a web as a non-woven fabric in this manner, the fibers of the non-woven fabric can be heat-melted to further bond the fibers, if necessary. Then, embossing can be applied to further strengthen the bond between the fibers.

Further, according to the present invention, there is provided a floppy disk using the above nonwoven fabric as a liner.
The floppy disk of the present invention comprises a magnetic disk having a magnetic layer formed on the surface thereof, two liners arranged so as to contact both sides of the magnetic disk, an upper shell and a lower shell. ing. The magnetic disk has a hub fixed via a ring, and engages with a hub drive mechanism provided in the disk drive to rotate.

Notches for the magnetic head to access the magnetic disk are formed in the upper shell and the lower shell. The cutout is usually covered by a shutter provided so as to cover the cutout. The shutter is slidable by a shutter spring.

The two liners are arranged between the magnetic disk and the upper shell and the lower shell, respectively. The liner exists in at least approximately the same space as the magnetic layer of the magnetic disk. Further, the liner has notches substantially similar to the notches of the upper shell and the lower shell, and the magnetic head can access the magnetic layer of the magnetic disk by aligning the positions with the notches of the upper shell and the lower shell. It is like this.

The liner is fixed to the upper and lower shells so that it does not move to prevent access to the magnetic head through the notch. The liner is secured to the upper and lower shells in alignment with the notches, for example using spot welding.

A lifter is arranged between the lower shell and the liner, whereby the liner and the magnetic disk come into close contact with each other and the surface of the magnetic disk is cleaned.

[0039]

The present invention will be described in more detail with reference to the following examples. It goes without saying that the scope of the present invention is not limited to the examples. In the following description, parts represent parts by weight unless otherwise specified. Prior to Examples and Comparative Examples, a method for measuring foam density, foam retention and foam hardness in Examples and Comparative Examples, and a method for evaluating the coating state of a nonwoven fabric binder will be described.

<Foam Density> 10 g of the non-woven fabric binder was stirred with a hand mixer for 2 minutes to foam, and then 100
Only 100 cc of the foam was placed in a cc measuring cylinder, the weight at that time was measured, and the density of the foam was calculated.

<Foam Retaining Property> 100 cc of the above foam alone was placed in a 100 cc graduated cylinder, and the amount of foam in the graduated cylinder after standing for 1 minute was read. Retention was calculated.

[0042]

[Equation 1]

<Hardness of Bubbles> The bubbles were sandwiched between two slide glasses, and the change when lightly pressed with a finger was observed, and ranked according to the following criteria. ○: Bubbles remained △: Bubbles liquefied a little ×: Bubbles liquefied

<Coating state of binder for non-woven fabric> The surface of the produced non-woven fabric was observed by SEM and the coating state of the binder on the fiber was ranked as follows. ○: The fiber surface is uniformly covered. △: The fiber surface is partially covered. ×: The fiber surface is not covered at all.

[Example 1] Acrylic emulsion (Good
rich 26120, non-volatile components 40% by weight, pH = 6),
1.5 wt% (solid content ratio) of triethanolamine lauryl sulfate was added to each to prepare a nonwoven fabric binder. The non-woven fabric binder thus obtained was foamed with a hand mixer, and the density of the resulting foam, the retention of the foam and the hardness of the foam were measured by the above methods. Table 1 shows the results. Next, a rayon web was coated with a foamed non-woven fabric binder so that the impregnated amount was 15% by weight (solid content). Then, this rayon web is dried at 150 ° C. for 1
After drying and heat treatment for 0 minutes, the fibers of the web were bonded to each other to obtain a nonwoven fabric. The coated state of the non-woven fabric binder in the non-woven fabric thus obtained was evaluated by the above method. Table 1 shows the results.

Example 2 Styrene acrylonitrile rubber (NS4310 manufactured by BASF, non-volatile component 30% by weight, pH =
6.3) with 1.5% and 1.0% by weight of sodium lauryl sulfate and triethanolamine, respectively.
(Solid content ratio) was added to prepare a nonwoven fabric binder.
The non-woven fabric binder thus obtained was foamed with a hand mixer, and the density of the resulting foam, the retention of the foam and the hardness of the foam were measured by the above methods. Table 1 shows the results. Next, a rayon web was coated with a foamed non-woven fabric binder so that the impregnated amount was 15% by weight (solid content). Then, this rayon web is heated at 150 ° C. for 10 minutes.
After drying and heat treatment for minutes, the fibers of the web were bonded to each other to obtain a nonwoven fabric. The coated state of the non-woven fabric binder in the non-woven fabric thus obtained was evaluated by the above method. Table 1 shows the results.

[Comparative Example 1] The same procedure as in Example 1 was carried out except that sodium dodecylbenzenesulfonate was used in place of lauryl sulfate, and the density of the foam, the retention of the foam and the foam were obtained. Was measured, and the coating state of the binder was also evaluated. Table 1 shows the results.

[0048]

[Table 1]

As is apparent from the results in Table 1, when triethanolamine lauryl sulfate and sodium lauryl sulfate and triethanolamine are added to the binder for the non-woven fabric, the foam state in the foam coating becomes good. As a result, it can be seen that when the web is foam-coated with the nonwoven fabric binder, the inside of the web is sufficiently covered.

[0050]

As described above, according to the present invention,
Provided is a binder for a non-woven fabric, which can be uniformly applied to the inside of the non-woven web. Further, by using such a binder for a non-woven fabric, a non-woven fabric for a floppy disk liner capable of preventing the occurrence or abrasion of the surface of the floppy disk with little or no lint and a method for producing the same. Further, by using such a nonwoven fabric for a floppy disk liner, a highly durable and error-free floppy disk can be provided.

Claims (7)

[Claims] 1. A non-woven fabric binder comprising: (a) an aqueous emulsion; and (b) an alkyl sulfate. 2. The non-woven fabric binder according to claim 1, wherein the alkyl sulfate is an alkyl sulfate alkanolamine salt. 3. The non-woven fabric binder according to claim 2, wherein the alkanolamine is triethanolamine. 4. The non-woven fabric binder according to claim 1, wherein the alkyl sulfate is lauryl sulfate. 5. A non-woven fabric for a floppy disk liner, characterized in that the non-woven fabric binder according to any one of claims 1 to 4 is used to bond fibers and coat the fiber surface. 6. The non-woven fabric binder according to claim 1 is foamed and then applied to a web to bond the fibers of the web and coat the surface of the fiber. And a method for producing a nonwoven fabric for a floppy disk liner. 7. A floppy disk using the nonwoven fabric for a floppy disk liner according to claim 5.