JPH08120195A - Antistatic coating and antistatic film and antistatic sheet having the same film formed thereon - Google Patents

Abstract

PURPOSE: To obtain an antistatic coating containing an electrically conductive polyaniline capable of forming an antistatic film good in antistatic properties and transparency, an antistatic film and an antistatic sheet having the film formed thereon. CONSTITUTION: This antistatic coating is constituted by uniformly dispersing a powdery or a granular material of an electrically conductive polyaniline in an amount of 2-40 pts.wt. based on 10 pts. wt. thermoplastic resin in a resin varnish, prepared by dissolving the thermoplastic resin in a volatile solvent and having 5-100cP viscosity and providing a state of the electrically conductive polyaniline powder or granular material substantially separated into primary particles. This antistatic film is constituted by forming a film of the antistatic coating on at least one surface of a thermoplastic resin film. Furthermore, this antistatic sheet is constituted by forming the film of the antistatic coating on at least one surface of a thermoplastic resin sheet or directing the film of the antistatic film toward the outside, laminating and integrating the antistatic film with at least one surface of the thermoplastic resin sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antistatic coating in which conductive polyaniline powder particles are uniformly dispersed, an antistatic film and an antistatic sheet having the coating film formed thereon.

[0002]

2. Description of the Related Art Synthetic resin films and sheets having an antistatic layer formed on the surface have an antistatic effect and are therefore used as wall coverings and floor coverings in operating rooms, dust-free rooms, etc. Further, in semiconductor manufacturing factories, it is used as a cover of a transfer unit in a wafer cleaning process, an outer plate of an apparatus, and the like.

The antistatic layer of such a film or sheet is roughly classified into one containing a surfactant, one containing a metal oxide, one containing carbon powder, and one formed of a conductive polymer. You can

However, the antistatic layer containing a surfactant does not have a constant antistatic property because the surfactant bleeds out, and the antistatic effect is not constant because the surface resistance fluctuates significantly depending on humidity and temperature. There is a drawback that.

Further, the antistatic layer containing the metal oxide is apt to drop off the metal oxide. Therefore, when used in a wafer cleaning process, for example, the dropped metal oxide adheres to the wafer, resulting in a high rate of defective products. There is a drawback that

Further, the antistatic layer containing carbon powder has a drawback that it cannot be seen through because it is black and opaque. Further, since the carbon powder easily falls off, it has the same disadvantages as the antistatic layer containing the metal oxide. is there.

On the other hand, an antistatic layer formed of a conductive polymer has been attracting attention in recent years, because it has a constant and antistatic effect and is free from the risk of foreign matter falling off. This is a conductive polyaniline antistatic layer.

[0008]

However, the above-mentioned conductive polyaniline is a polymer which is insoluble in an organic solvent and does not melt even when heated, and as it is, it is difficult to form a film by the same method as a general-purpose resin. Therefore, for example, as disclosed in JP-A-6-166748, by reacting a reduced polyaniline with a polyurethane compound having a functional group that reacts with an aromatic secondary amine at both ends, It is necessary to form a film as a polyaniline derivative having a crosslinkable structure that is soluble or gellable in a solvent. Therefore, there is a problem that the process up to the film formation becomes complicated and the cost increases.

Therefore, the inventors of the present invention have conceived that the conductive polyaniline is made into a paint and the antistatic coating film can be easily formed only by coating. However, in the commercially available conductive polyaniline powder particles, the primary particles are secondarily aggregated to form 3-1.
Since it is a large powder particle of about 00 μm, has a low bulk specific gravity, and has a large oil absorption amount (hard to wet), it is extremely difficult to uniformly disperse the primary particles into the coating base material. We have encountered a difficult problem in that a dispersion that can form a thin antistatic coating film having excellent transparency and antistatic property cannot be obtained when dispersed in the state of the next agglomeration.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polyaniline-containing antistatic paint capable of forming a thin antistatic paint film having excellent transparency and antistatic property, and a coating film thereof. An object of the present invention is to provide an antistatic film and an antistatic sheet formed with.

[0011]

In order to achieve the above object, the antistatic coating of the present invention comprises a conductive varnish of a conductive polyaniline in a resin varnish having a viscosity of 5 to 100 cps in which a thermoplastic resin is dissolved in a volatile solvent. The powder particles are mixed with the above thermoplastic resin 10
It is characterized by being uniformly dispersed at a ratio of 2 to 40 parts by weight with respect to parts by weight.

The antistatic film of the present invention is characterized in that a coating film of the antistatic paint is formed on at least one surface of a thermoplastic resin film, and the antistatic sheet of the present invention is A coating film of the antistatic paint is formed on at least one surface of the thermoplastic resin sheet, or the antistatic film is laminated and integrated on at least one surface of the thermoplastic resin sheet with the coating film as the outside. To do. In these antistatic films and sheets, it is desirable to form a coating film of antistatic paint to a thickness of 5 μm or less.

[0013]

When a resin varnish having a viscosity of 5 to 100 cps in which a thermoplastic resin is dissolved in a volatile solvent is used as the paint base, like the antistatic paint of the present invention, the dispersibility of conductive polyaniline powder particles is improved. Therefore, when the powder particles are dispersed while applying a high shearing force with an appropriate dispersing device, the powder particles are substantially dispersed in the resin varnish in a state of being substantially separated into primary particles. However, when the viscosity of the resin varnish is higher than 100 cps, the resin varnish is in a so-called "idle state" in the dispersing device, and it becomes difficult to disperse the conductive polyaniline powder particles in a state where they are substantially separated into primary particles. Further, when the viscosity of the resin varnish is lower than 5 cps, the obtained antistatic coating becomes a coating having an extremely low viscosity, and the coating characteristics deteriorate.

The antistatic coating composition of the present invention contains powder particles of conductive polyaniline in an amount of 2 to 40 parts by weight with respect to 10 parts by weight of the thermoplastic resin in the resin varnish. Since it is dispersed evenly in the separated state,
When the volatile solvent is dried and removed after application to form a coating film,
The primary particles are in continuous contact with each other in the coating film, and exhibit good antistatic property with a surface resistivity of about 10 ⁵ to 10 ⁸ Ω / □. When the conductive polyaniline powder particles are dispersed in the above blending ratio, the transparency of the coating film will not be significantly reduced. Further, since the particle size of the primary particles is about 0.1 to 0.2 μm, it is possible to form an extremely thin coating film having a film thickness of about 2 to 3 times the particle size. When the blending ratio of the conductive polyaniline is less than the above range, the transparency of the coating film is improved, but the surface resistivity is increased, so that it becomes difficult to form a coating film having good antistatic property. On the contrary, when the blending ratio of the conductive polyaniline exceeds the above range, the antistatic property of the coating film is improved, but the transparency is considerably lowered,
Further, the strength of the coating film also decreases due to the lack of the thermoplastic resin.

Further, the antistatic film of the present invention is a thermoplastic resin film having a coating film of the above antistatic paint formed on at least one surface thereof, and the antistatic sheet of the present invention comprises:
A coating film of the above antistatic paint is formed on at least one surface of the thermoplastic resin sheet, or the above antistatic film is laminated and integrated on at least one surface of the thermoplastic resin sheet with the coating film outside. Therefore, both are easy to manufacture. And since the coating film of the antistatic paint on the surface has the surface resistivity as described above and exhibits a good antistatic effect, the antistatic film or sheet of the present invention sufficiently prevents the adhesion of dust and the like. can do. Further, in this coating film, the ratio of the conductive polyaniline powder particles and the thermoplastic resin serving as the binder thereof is as described above, and the conductive polyaniline powder particles are firmly bonded by the thermoplastic resin. In addition, the coating film has high strength, and the conductive polyaniline powder particles are hard to fall off, and a good antistatic effect can be maintained for a long period of time. Moreover, this coating film is transparent, and in particular, when the coating film formed to a thickness of 5 μm or less has a good total light transmittance of about 60 to 80%,
There is no need to worry about hindering transparency or see-through. Furthermore, since this coating film is a transparent film colored in green with conductive polyaniline particles, it also has a function of blocking heat rays (infrared rays).

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of the antistatic film of the present invention. In this antistatic film A, the surface of a transparent thermoplastic resin film 1 is coated with the antistatic paint of the present invention. The coating film 2 is formed by drying. The coating film 2 of this antistatic paint may be formed on both front and back surfaces of the thermoplastic resin film 1.

As the thermoplastic resin film 1, for example, transparent films of polyvinyl chloride, polymethylmethacrylate, polycarbonate, polyethylene terephthalate, etc. are preferably used, but other transparent films of thermoplastic resins may of course be used. You can The thickness of the film is not particularly limited, and a film having an appropriate thickness may be selected in consideration of the application and the like.

The antistatic paint of the present invention used for forming the coating film 2 is 5 to 100c in which a thermoplastic resin is dissolved in a volatile solvent.
In a resin varnish having a viscosity of ps, conductive polyaniline powder particles are added in an amount of 2 to 40 with respect to 10 parts by weight of the thermoplastic resin.
It is prepared by uniformly dispersing it in a ratio of parts by weight.

As the thermoplastic resin of the resin varnish, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer resin having a vinyl acetate content of 10% by weight or less, and the like are preferably used, but polymethyl methacrylate and polycarbonate. Of course, a thermoplastic resin such as polyethylene terephthalate can also be used. Further, as the volatile solvent of the resin varnish, for example, cyclohexanone, methyl isobutyl ketone, etc. are used alone or in combination, but other volatile solvents can of course be used.

The resin varnish has a viscosity of 5 to 100 cp.
It is necessary to adjust the compounding amount of the thermoplastic resin so that the amount becomes s and to prepare by dissolving in a volatile solvent. Since the resin varnish having a viscosity of 5 to 100 cps has good dispersibility of the conductive polyaniline powder particles, when the powder particles are added and agitated while applying a high shearing force with an appropriate dispersing device, the powder particles are substantially dispersed. This is because they can be uniformly dispersed in the resin varnish in the state of being separated into primary particles. Viscosity of resin varnish is 100c
If it is higher than ps, it becomes a so-called "idling" state in the dispersing device, and it becomes difficult to disperse the conductive polyaniline powder particles substantially in the state of being separated into primary particles, and
When the viscosity of the resin varnish is lower than 5 cps, the obtained antistatic paint is a low-viscosity paint having poor coating properties, and in any case, the antistatic paint that can achieve the object of the present invention cannot be obtained.

As the conductive polyaniline, for example, Versicon manufactured by Allied-Signal Co., Ltd. is preferably used. This is a powder particle having a particle size of about 3 to 100 μm in which primary particles of polyaniline of about 0.1 to 0.2 μm are secondarily aggregated, and has a low bulk specific gravity of about 0.30 and an oil absorption amount of carbon. It is as large as black. The mixing ratio of the conductive polyaniline powder particles needs to be 2 to 40 parts by weight with respect to 10 parts by weight of the thermoplastic resin in the resin varnish. When conductive polyaniline powder particles are uniformly dispersed in a resin varnish at this ratio to prepare an antistatic coating, the antistatic property (antistatic property) having a surface resistivity of about 10 ⁵ to 10 ⁸ Ω / □ is obtained. This is because it is possible to form a different coating film, the transparency of the coating film is not significantly lowered, and the heat ray shielding effect of the coating film is good. When the blending ratio of the conductive polyaniline powder particles is less than 2 parts by weight, the transparency of the coating film formed is improved, but the surface resistivity increases, so that it is difficult to form a coating film having good antistatic property. In addition, the degree of coloring of green by the conductive polyaniline powder particles becomes extremely light, so that the heat ray blocking effect is significantly reduced. On the contrary, when the conductive polyaniline particles are more than 40 parts by weight, the antistatic property and the heat ray blocking effect of the coating film are improved, but the transparency is considerably lowered, and the coating film strength is also decreased due to the lack of the thermoplastic resin. descend. Therefore, in any case, an antistatic paint which can achieve the object of the present invention cannot be obtained.
A more preferable mixing ratio of the conductive polyaniline particles is 5 to 20 with respect to 10 parts by weight of the thermoplastic resin in the resin varnish.
The range is parts by weight.

As a device for dispersing the conductive polyaniline powder particles in the resin varnish, for example, a sand mill, a ball mill, a homogenizer or the like is used. Whichever dispersing device is used, it is larger than the cohesive force of the conductive polyaniline powder particles. It is necessary to apply a shearing force and stir well to obtain an antistatic coating in which the powder particles are substantially uniformly dispersed in a state of being separated into primary particles.

The antistatic coating material of the present invention thus obtained has a viscosity of about 30 to 400 cps and good coating properties. In addition, in order to suppress reaggregation of the dispersed primary particles, an appropriate amount of a dispersant may be added in some cases. As the dispersant, for example, dodecylbenzenesulfonic acid or the like is preferably used. When transparency is not required, titanium oxide powder and other pigments may be mixed to form an opaque antistatic paint.

Coating film 2 of antistatic film A illustrated in FIG.
Is formed by applying the antistatic paint of the present invention as described above to a uniform thickness on the surface of the thermoplastic resin film 1 with a coating device such as a roll coater or a blade coater, and drying and removing the volatile solvent. It has a structure in which primary particles of conductive polyaniline are continuously contacted with each other by a thermoplastic resin, and has a surface resistivity of 10 ⁵ to 10 ⁸
Demonstrates good antistatic property of about Ω / □.

The preferable thickness (dry film thickness) of the coating film 2 is 5 μm.
m or less, and a more preferable thickness is 0.5 to 3 μm. When such a thin coating film 2 is formed, 60 to 80%
It is possible to obtain an antistatic film having a degree of total light transmittance and good transparency, transparency and the like. The thickness of coating film 2 is 5μ
When it is larger than m, the total light transmittance is lowered and the transparency and the like are deteriorated, which is not preferable. The thinner this coating film 2 is, the more the total light transmittance is improved. Since the transparent green color becomes extremely light and the heat ray blocking effect is greatly reduced,
As described above, the thickness is preferably 0.5 μm or more.

FIG. 2 is a sectional view showing an embodiment of the antistatic sheet of the present invention. In this antistatic sheet B, a coating film 2 of the antistatic paint is formed on one surface of a thermoplastic resin sheet 3. It is a thing. The coating film 2 may be formed on both front and back surfaces of the sheet 3.

As the thermoplastic resin sheet 3, for example, a transparent sheet of polyvinyl chloride, polymethylmethacrylate, polycarbonate, polyethylene terephthalate or the like is preferably used, but other transparent sheets of thermoplastic resin may of course be used. You can The thickness of the sheet is not particularly limited, and a sheet having an appropriate thickness may be selected in consideration of the application and the like. The term "sheet" used here is a broad term that includes a plate.

Since the thickness and constitution of the coating film 2 are the same as those of the antistatic film, the description thereof will be omitted.

Needless to say, such an antistatic sheet B also exhibits good antistatic effect and heat ray blocking effect by the coating film 2 of the antistatic paint on the surface.

FIG. 3 is a cross-sectional view showing another embodiment of the antistatic sheet of the present invention. This antistatic sheet C is made of the above-mentioned antistatic film A which has the coating film 2 as the outside and is thermoplastic. The resin sheet 3 is laminated and integrated on the surface. The antistatic film A may be laminated and integrated on both front and back surfaces of the thermoplastic resin sheet 3 if necessary.

The above-mentioned sheet is preferably used as the thermoplastic resin sheet 3, but any transparent thermoplastic resin sheet can be laminated and integrated so as not to separate from the thermoplastic resin film 1 of the antistatic film A. All can be used.

The most suitable means for laminating and integrating the antistatic film A and the thermoplastic resin sheet 3 is to thermocompress the antistatic film A to the thermoplastic resin sheet 3 using a hot press machine or a thermocompression bonding roll. If desired, it may be bonded using a suitable adhesive. In some cases, an antistatic film from which the coating film 2 is easily peeled off may be laminated and integrated with the thermoplastic resin sheet 3 with the coating film 2 inside. In this way, the film 1 can be peeled off at the time of use to expose the coating film 2.

Needless to say, the antistatic sheet C as described above also has a good antistatic effect due to the coating film 2 of the antistatic paint on the surface.

Next, more specific examples and comparative examples of the present invention will be described.

[Example 1] Vinyl chloride-vinyl acetate copolymer resin containing 5% by weight of vinyl acetate in a volatile mixed solvent prepared by mixing cyclohexanone and methyl isobutyl ketone in a weight ratio of 3: 7 (Kanebuchi Chemical Industry). Co., Ltd. product number M-1
008, average degree of polymerization: 800) was dissolved to prepare a resin varnish having a resin concentration of 3.9% by weight and a viscosity of about 10 cps.

This resin varnish was transferred to a sand mill, and conductive polyaniline powder particles (product name manufactured by Allied-Signal Co., Ltd.
Versicon) is added at a ratio of 20 parts by weight to 10 parts by weight of resin in the resin varnish at room temperature.
The mixture was stirred for 0 minute and uniformly dispersed to obtain an antistatic paint of the present invention having a viscosity of about 100 cps.

This antistatic coating is applied to one side of a polyvinyl chloride film having a thickness of 0.25 mm by a roll coater and dried to form a green transparent coating film having a thickness of about 1 μm. Got The surface resistivity of the coating film of this antistatic film was measured using a surface resistance meter (product name: Hiresta manufactured by Mitsubishi Petrochemical Co., Ltd.), and it was 10 ⁷ Ω / □, indicating that the antistatic property was good. Was there. Further, the total light transmittance of this antistatic film was measured using a light transmittance measuring device (product name Haze Computer manufactured by Suga Test Instruments Co., Ltd.), and it was 75%, and the transparency was also good. .

Further, this antistatic film was laminated on a polyvinyl chloride sheet having a thickness of 3 mm with the coating film on the upper side, and thermocompression bonded under the conditions of a temperature of 160 ° C. and a pressure of 16 kg / cm ^{2 with} a hot press machine to obtain a book. An antistatic sheet of the invention was obtained. When the total light transmittance of this antistatic sheet was measured, a result of 70% was obtained.

Example 2 A resin varnish having a resin concentration of 10% by weight and a viscosity of about 70 cps was prepared in the same manner as in Example 1 except that the compounding amount of the vinyl chloride-vinyl acetate copolymer resin was changed. Then, the compounding ratio of the conductive polyaniline particles to this resin varnish is set to be the resin content 1 in the resin varnish.
An antistatic coating material of the present invention having a viscosity of about 250 cps was obtained in the same manner as in Example 1 except that the content was changed to 5 parts by weight with respect to 0 parts by weight.

Using this antistatic paint, an antistatic film was prepared in the same manner as in Example 1, and the surface resistivity and total light transmittance thereof were measured. The surface resistivity was 10 ⁸ Ω / □. The light transmittance was 70%, and both the antistatic property and the transparency were good.

Further, using this antistatic film, Example 1 was used.
An antistatic sheet was prepared in the same manner as in 1. above, and the total light transmittance thereof was measured. The result was 65%.

Comparative Example 1 A resin varnish having a resin concentration of 2% by weight and a viscosity of about 2 cps was prepared in the same manner as in Example 1 except that the blending amount of the vinyl chloride-vinyl acetate copolymer resin was changed. Then, in the same manner as in Example 1 except that the mixing ratio of the conductive polyaniline particles to this resin varnish was changed to 1 part by weight relative to 10 parts by weight of the resin content in the resin varnish, about 5 cps. An antistatic paint having a viscosity of

Since this antistatic coating has poor coating properties, a brush coating was applied to the surface of the polyvinyl chloride film used in Example 1 to form a coating film having a thickness of about 10 μm, and an antistatic film was obtained. Then, the surface resistivity and the total light transmittance of this antistatic film were measured in the same manner as in Example 1, and the surface resistivity was 10 ¹³ Ω / □ and the total light transmittance was 80%. Was good but inferior in antistatic property.

Comparative Example 2 A resin varnish having a resin concentration of 12% by weight and a viscosity of about 150 cps was prepared in the same manner as in Example 1 except that the blending amount of the vinyl chloride-vinyl acetate copolymer resin was changed. Then, in the same manner as in Example 1 except that the mixing ratio of the conductive polyaniline particles to this resin varnish was changed to 50 parts by weight with respect to 10 parts by weight of the resin content in the resin varnish, about 3000 cps. An antistatic paint having a viscosity of

This antistatic paint was brush coated on the surface of a polyvinyl chloride film in the same manner as in Comparative Example 1 to give a film thickness of about 25 μm.
To form an antistatic film. Then, the surface resistivity and the total light transmittance of this antistatic film were measured in the same manner as in Example 1, and the surface resistivity was 10 ² Ω / □,
The total light transmittance was 8%, and the antistatic property was good, but the transparency was poor. Further, in the coating film of this antistatic film, the conductive polyaniline particles were seen to fall off when rubbed.

[0047]

As is apparent from the above description, since the antistatic coating material of the present invention uses a resin varnish having a viscosity of 5 to 100 cps as the coating material base, the conductive polyaniline particles are substantially primary particles. can be uniformly dispersed in the resin varnish in a separated state, the Moreover, since the mixing ratio of the particles relative to the resin content of 10 parts by weight of the resin varnish is a ratio of 2 to 40 parts by weight, ¹⁰⁵ to It is possible to form an excellent antistatic property and transparency having a surface resistivity of about 10 ⁸ Ω / □ and a good coating film made of a heat ray shield.

Then, the antistatic film of the present invention in which the coating film of the antistatic paint is formed on at least one surface of the thermoplastic resin film, and the present invention in which the antistatic film is laminated and integrated on at least one surface of the thermoplastic resin sheet. The anti-static sheet of
Both have the effect of preventing electrification by the coating film of antistatic paint on the surface and being able to satisfactorily prevent dust from adhering. Moreover, since transparency and heat ray blocking property are good, various transparency and heat ray blocking are required. In addition, since the coating film has high strength, there is almost no fear that the conductive polyaniline particles will fall off due to damage of the coating film or friction.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an antistatic film of the present invention.

FIG. 2 is a sectional view showing an embodiment of the antistatic sheet of the present invention.

FIG. 3 is a sectional view showing another embodiment of the antistatic sheet of the present invention.

[Explanation of symbols]

 1 thermoplastic resin film 2 coating film of antistatic paint 3 thermoplastic resin sheet A antistatic film B, C antistatic sheet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Sakai 2-3-3 Azuchicho, Chuo-ku, Osaka City Takiron Co., Ltd.

Claims (7)

[Claims] 1. A thermoplastic resin dissolved in a volatile solvent.
An antistatic paint comprising electrically conductive polyaniline powder particles uniformly dispersed in a resin varnish having a viscosity of 100 cps at a ratio of 2 to 40 parts by weight with respect to 10 parts by weight of the thermoplastic resin. 2. An antistatic film formed by forming a coating film of the antistatic paint according to claim 1 on at least one surface of a thermoplastic resin film. 3. The antistatic film according to claim 2, wherein the antistatic coating film is formed to a thickness of 5 μm or less. 4. A thermoplastic resin sheet on at least one side,
An antistatic sheet formed by forming a coating film of the antistatic paint according to claim 1. 5. The antistatic sheet according to claim 4, wherein the antistatic coating film is formed to a thickness of 5 μm or less. 6. An antistatic film having a coating film of the antistatic paint according to claim 1 formed on one surface of a thermoplastic resin film, and the integrated coating is laminated on at least one surface of the thermoplastic resin sheet with the coating film facing outward. Antistatic sheet consisting of. 7. The antistatic sheet according to claim 6, wherein the coating film of antistatic paint is formed to a thickness of 5 μm or less.