JPH0741697A - Antistatic paint and antistatic molded article coated with the paint - Google Patents

Abstract

PURPOSE:To obtain an antistatic paint having excellent antistaticity and exhibiting excellent surface-staining resistance when applied to a substrate such as plate or film of plastics, etc., and provide an antistatic molded article coated with the antistatic paint. CONSTITUTION:This antistatic paint contains a hydroxyl-containing binder resin, electrically conductive alkali metal titanate whisker and an organic solvent as main components. There is also provided an antistatic molded article produced by applying a specific amount of the antistatic paint to a substrate, drying the paint and molding the obtained laminate, to an antistatic paint having decreased content of electrically conductive fine powder by the use of the above composition to reduce the production cost and suppress the stain-deposition on the coating film surface without lowering the antistaticity and to a molded article coated with the antistatic paint.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an antistatic coating composition which has excellent antistatic properties and which, when applied to a plate such as a plastic plate or a substrate such as a film, has excellent resistance to surface contamination of the coating film. It also relates to an antistatic molded product obtained by applying the same.

[0002]

2. Description of the Related Art In many cases, containers for semiconductor wafers, clean benches, clean rooms and other electronic / electrical parts, floor materials / wall materials for semiconductor manufacturing plants, etc. are required to have antistatic properties.

As an antistatic coating applied to such a member, for example, JP-A-60-181171 discloses:
Disclosed is a colorable antistatic coating material containing conductive fine powder in which tin oxide is doped on the surface of titanium oxide.

[0004]

However, in the antistatic coating composition in the conventional example, since the spherical powder in which tin oxide is doped on the surface of titanium oxide is used as the conductive fine powder, the conductivity is exhibited. In order to let
It is necessary to include 50% by weight or more of these fine powders in the paint. Therefore, in addition to the problem of high manufacturing cost, both titanium oxide and tin oxide have high surface hardness, and when a coating film is formed by applying a paint to a substrate or the like, spherical particles with high surface hardness are Since it occupies more than half the amount, when a metal or the like comes into contact, the spherical particles scrape off the metal, and the coating film surface is liable to be contaminated.

The present invention has been made by paying attention to such a problem, and its object is to reduce the addition amount of the conductive fine powder without lowering the antistatic property.
An object of the present invention is to provide an antistatic coating material that reduces the manufacturing cost and improves the stain resistance of the coating film surface, and an antistatic molded article to which the coating material is applied.

[0006]

That is, the invention according to claim 1 is characterized in that it contains a binder resin containing a hydroxyl group, a conductive alkali metal titanate whisker, and an organic solvent as main components, for antistatic treatment. It concerns paints.

In the present invention, since the conductive powder for expressing conductivity is changed from the conventional spherical particles to the acicular alkali metal whiskers, the particles are elongated as compared with the conventional spherical particles. It is possible to obtain a conductive effect with a smaller amount of mixture than that of, and to improve the surface contamination resistance of the coating film.

Next, the invention according to claim 2 is premised on the antistatic paint according to claim 1, wherein the conductive alkali metal titanate whiskers are contained in a proportion of 3 to 20% by weight based on the total amount of the paint. It is characterized by becoming.

According to the second aspect of the present invention, the conductive alkali metal titanate whiskers are contained in an amount of 3 to 20% by weight, preferably 5 to 15% by weight, based on the total amount of the coating material to prevent static electricity. The production cost can be reduced without lowering the property, and the susceptibility to stains on the coating film surface can be more effectively improved.

Here, as a method of expressing conductivity,
There are methods by directly contacting conductive particles, and by flowing an electric current by a tunnel effect between particles that are far apart. Easy to do,
In addition, the tunnel effect is more likely to occur when the particles are sharp. Therefore, by replacing the conductor with a needle-shaped one, the mixing amount can be reduced. Further, since the binder resin is contained in the coating material in a large amount as much as the content of the conductive powder is reduced, it is possible to improve the prevention of the coating film contamination when the metal comes into contact with the coating material.

Next, the invention according to claim 3 is based on the antistatic coating material according to any one of claims 1 and 2, wherein the acid having a carboxyl group is contained in an amount of 0.2 to 2% by weight based on the total weight of the coating material. It is characterized in that it is further contained in a ratio.

In the invention according to claim 3, the acid having a carboxyl group is contained in such a ratio with respect to the total amount of the coating material to improve the dispersibility of the conductive alkali metal titanate whiskers and prevent the sedimentation. This makes it possible to prevent the conductive alkali metal titanate whiskers from settling even if the paint is stored for a long time after production, and the storage stability of the paint can be improved. When the mixing ratio of the acid having a carboxyl group is less than 0.2% by weight based on the total amount of the coating material, the dispersibility and the effect of preventing sedimentation are small.
If it exceeds 2% by weight, the performance such as chemical resistance and durability of the coating film may deteriorate.

Further, the invention according to claim 4 is the invention according to claim 1.
The present invention relates to an antistatic molded article, which is obtained by molding a laminate obtained by applying a predetermined amount of the antistatic coating composition according to any one of 3 to 3 onto a substrate and drying the coating.

According to the invention of claim 4,
An antistatic molded article, which is obtained by applying the antistatic coating material according to any one of claims 1 to 3, has excellent antistatic properties, has improved easiness of stains on the coating film surface, and has reduced manufacturing costs. Can be provided. Suitable applications of such antistatic molded products include, for example, electrostatic shields, resistors, circuits, switch contacts, electromagnetic wave shields, and the like.

In such technical means, the antistatic coating material contains a binder resin containing a hydroxyl group, a conductive alkali metal titanate whisker, and an organic solvent as main components.

First, the hydroxyl group-containing binder resin is not particularly limited as long as it contains a hydroxyl group, and examples thereof include polyvinyl alcohol, partially saponified vinyl acetate, polyvinyl acetal, and alkyl acrylate-hydroxyalkyl (meth) acrylate copolymer. Examples thereof include a combination, a partially saponified vinyl chloride-vinyl acetate copolymer, and a vinyl chloride-hydroxyalkyl (meth) acrylate copolymer.

Next, the conductive alkali metal titanate whiskers are not particularly limited, and known ones can be used. Examples of such conductive alkali metal titanate whiskers include (1) general formula M ₂ O · aTiO 3.
_x · bH ₂ O (in the formula, M is an alkali metal such as Li, Na, or K; 0 <a ≦ 8, 0 ≦ b ≦ 4, 0 <x <2; a,
b and x are represented by real numbers, and are generally referred to as alkali metal titanate compounds or bronze alkali metal titanate whiskers of conductive alkali metal titanate (I);
Alternatively, (2) the alkali metal titanate whiskers represented by the general formula M ₂ O · aTiO _y · bH ₂ O (wherein M, a, and b are the same as above; 0 <y ≦ 2) are conductive. (II) coated with one or more selected from metals and / or conductive metal oxides, metal halides, or other conductive metal compounds; or (3) general formula M ₂ O. aTiO _y · bH ₂ O (wherein
(M, a, b and y are the same as above), in producing the alkali metal titanate whisker group represented by the above, the raw material of the alkali metal titanate whiskers is a conductive metal oxide, halide or carbonate, The coexistence with one or more metal compounds such as nitrates or sulfates is carried out by reacting in a reducing atmosphere or reacting in an oxidizing atmosphere, and then, if necessary, reducing or doping treatment to obtain the titanium. Acid alkali metal whiskers are coated with one or more selected from conductive metals and / or conductive metal oxides, metal halides or other conductive metal compounds, or the alkali metal titanate Various conductive alkali metal titanates such as whisker particles in which at least the surface forms a eutectic with them (III); It can be exemplified one or two or more mixtures of Scar. These conductive alkali metal titanate whiskers can be produced by a known production method or can be obtained commercially. The conductive alkali metal titanate whiskers are needle-like in shape, and particularly preferably have a length of 3 to 30 μm and an aspect ratio of 3 to 150. Length is 3μ
If it is less than m or the aspect ratio is less than 3, the conductivity of the coating film may be insufficient, while the length is 30 μm.
When it exceeds m or the aspect ratio exceeds 150, the whiskers may be difficult to be uniformly dispersed in the paint, and the storage stability of the paint may be deteriorated. Further, the surface gloss after forming a coating film may be decreased. It is not preferable because it may worsen.

The organic solvent used in the present invention is not particularly limited, but one having a boiling point of about 60 to 160 ° C. is preferable. If the boiling point is less than 60 ° C, the concentration or viscosity of the coating may change due to evaporation of the solvent during storage or coating of the coating, while if the boiling point exceeds 160 ° C, the drying process may take a long time. This is because it may take some time.
Also, those having strong volatility are not preferable because the concentration and viscosity of the paint may change due to evaporation of the solvent during storage or coating of the paint. From the viewpoint of affinity with the conductive alkali metal titanate whiskers, a solvent containing oxygen is preferable.

Specific examples of the organic solvent include cyclohexanone, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), diethylene glycol dimethyl ether, butyl acetate, isopropyl acetone, methyl ethyl ketone, anisole and the like. Suitable examples include: These may be used alone or in combination of two or more.

The antistatic coating composition according to claim 1 comprises the binder resin containing a hydroxyl group, the conductive alkali metal titanate whiskers, and the organic solvent, for example, a high-speed rotary stirring device, a sand mill, a ball mill, an attritor, and three It can be obtained by mixing with a general mixing device using rolls, etc., but if the conductive alkali metal titanate whiskers are broken, the conductivity will decrease, so do not use a medium such as a high-speed rotation stirring device. It is preferable to use a mixing device.

On the other hand, the antistatic coating composition according to claim 2 is
It can be determined by including the conductive alkali metal titanate whiskers in a proportion of 3 to 20% by weight with respect to the total amount of the coating material and mixing them in a general mixing apparatus as described above to prepare.

The antistatic paint according to claim 3 is
0.2 to 2 of the acid having a carboxyl group with respect to the total amount of the coating
It can be determined by further containing it in the proportion of wt% and mixing and preparing it in a general mixing apparatus as described above. Here, the acid having a carboxyl group is not particularly limited, but preferred examples thereof include oleic acid, acrylic acid / mityyl methacrylate copolymer, and styrene / maleic acid copolymer.

The antistatic coating composition as set forth in any one of claims 1 to 3 thus prepared is prepared by a spray method, a bar coating method, a doctor blade method, a roll coating method, a dipping method or the like. It is used by applying it to an object by a general application method. Examples of the object include a vinyl chloride, polycarbonate, polymethacrylate, plastic plate such as ABS resin, or a plastic film. Further, a plate or a film made of an inorganic substance such as glass can also be an object.

The antistatic molded article according to claim 4 is formed by applying a predetermined amount of the antistatic coating composition according to any one of claims 1 to 3 to a desired object and drying the coating. It can be obtained by molding the laminate, or by applying a predetermined amount of paint to the object after molding and drying.

Here, the surface of the coating film may be polished by buffing or the like, if necessary. By buffing, it is possible to improve the gloss and stain resistance of the coating film, and since the debris of whiskers that easily fall off the surface is removed, it is possible to prevent the generation of dust,
A product suitable for a clean room or the like can be manufactured.

[0026]

According to the invention of claim 1, the conductive powder for exhibiting conductivity is changed from the conventional spherical particles to acicular alkali metal whiskers, so that the particles are elongated as compared with the conventional spherical particles. It is possible to obtain a conductive effect with a small amount of mixture, and it is possible to improve the surface contamination resistance of the coating film without lowering the antistatic property.

Next, according to the second aspect of the present invention, the conductive alkali metal titanate whiskers are used in an amount of 3 based on the total amount of the paint.
By containing it in a proportion of up to 20% by weight, the production cost can be reduced without lowering the antistatic property, and
It is possible to more effectively improve the easiness of stains on the surface of the coating film.

According to the invention of claim 3, the acid having a carboxyl group is contained in a proportion of 0.2 to 2% by weight with respect to the total amount of the coating material, so that the conductive alkali metal titanate whiskers are dispersed. It is possible to improve the property and prevent sedimentation, and even if the coating is manufactured and stored for a long period of time, the conductive alkali metal titanate whiskers do not settle, and the storage stability of the coating can be improved.

Further, according to the invention of claim 4, a predetermined amount of the antistatic coating composition according to any one of claims 1 to 3 is applied on a substrate and dried to obtain the antistatic coating composition. Provided is an antistatic molded article which is excellent in antistatic properties and which is improved in susceptibility to stains on the surface of a coating film and which has a reduced manufacturing cost, to which the antistatic coating material of any one of the above is applied.

[0030]

EXAMPLES Examples of the present invention will be described in detail below.

[Example 1] Conductive potassium titanate whiskers (Dentol WK-200, manufactured by Otsuka Chemical Co., Ltd.) 5% by weight 2-hydroxypropyl acrylate (10 mol%)-vinyl chloride (90 mol%) Polymer (Sekisui Chemical Co., Ltd., Eslec E-HA) 25% by weight Methyl ethyl ketone 30% by weight Cyclohexanone 40% by weight The above components were charged in a stainless steel container, stirred with a high-speed stirrer at 2000 rpm for 10 hours and mixed to give An antistatic paint according to the invention was prepared.

The antistatic paint thus obtained was applied to an ivory-colored hard PVC plate (thickness: 3 mm).
A bar coater (#
The antistatic plate according to the present invention was obtained by applying by the method 10) and drying with hot air at 40 ° C. for 2 hours.

Example 2 Conductive Potassium Titanate Whiskers (Otsuka Chemical Co., Ltd., Dentol WK-200) 10% by weight Acetal resin (Sekisui Chemical Co., Ltd., S-REC KS-5Z) 20% by weight Methylene Glycol monomethyl ether 70% by weight In the same manner as in Example 1 except that the above components were used, an antistatic coating material and an antistatic plate according to the present invention were obtained.

Example 3 Conductive potassium titanate whiskers (Dentol WK-200, manufactured by Otsuka Chemical Co., Ltd.) 15% by weight 2-hydroxyethyl methacrylate (20 mol%)-methyl methacrylate (80 mol%) Copolymer (manufactured by Sekisui Chemical Co., Ltd., S-REC KS-5Z) 20% by weight Methyl ethyl ketone 25% by weight Cyclohexanone 40% by weight In the same manner as in Example 1 using the above components, the antistatic agent according to the present invention A paint and an antistatic plate were obtained.

[Example 4] Conductive potassium titanate whiskers (Dentol WK-200, manufactured by Otsuka Chemical Co., Ltd.) 25% by weight 2-hydroxyethyl methacrylate (20 mol%)-methyl methacrylate (80 mol%) Copolymer (Sekisui Chemical Co., Ltd., S-REC KS-5Z) 15% by weight Methylethylketone 20% by weight Cyclohexanone 40% by weight In the same manner as in Example 1 using the above components, an antistatic coating and antistatic property A plate was obtained.

Example 5 Conductive Potassium Titanate Whiskers (Dentol WK-200, manufactured by Otsuka Chemical Co., Ltd.) 5% by weight 2-hydroxypropyl acrylate (10 mol%)-vinyl chloride (90 mol%) Polymer (Sekisui Chemical Co., Ltd., Eslec E-HA) 25% by weight Methyl ethyl ketone 30% by weight Cyclohexanone 40% by weight The above components were charged in a stainless steel container, stirred with a blade-type stirrer for 10 hours, and mixed. The antistatic coating composition according to (1) was prepared.

The antistatic paint thus obtained was applied to an ivory-colored PVC plate with a bar coater (# 1).
The antistatic plate according to the present invention was obtained by applying by the method 0) and drying at room temperature for 24 hours.

Example 6 Conductive potassium titanate whiskers (Otsuka Chemical Co., Ltd., Dentol WK-200) 10% by weight Acetal resin (Sekisui Chemical Co., Ltd., S-REC KS-5Z) 20% by weight Methyl ethyl ketone 30% by weight Cyclohexanone 40% by weight By using each of the above components, an antistatic coating material and an antistatic plate according to the present invention were obtained in the same manner as in Example 5.

Example 7 Conductive Potassium Titanate Whiskers (Otsuka Chemical Co., Ltd., Dentol WK-200) 15 wt% Butyral resin (Sekisui Chemical Co., Ltd., Eslec BH-5) 25 wt% Methyl ethyl ketone 30% by weight Cyclohexanone 30% by weight Using the above components, an antistatic coating material and an antistatic plate according to the present invention were obtained in the same manner as in Example 5.

Example 8 Conductive Potassium Titanate Whiskers (Otsuka Chemical Co., Ltd., Dentol WK-200) 3 wt% Acetal resin (Sekisui Chemical Co., Ltd., Eslek KS-5Z) 28 wt% Methyl ethyl ketone 30 wt% cyclohexanone 40 wt% Using each of the above components, an antistatic coating material and an antistatic plate were obtained in the same manner as in Example 5.

Example 9 Conductive Potassium Titanate Whiskers (Otsuka Chemical Co., Ltd., Dentol WK-200) 17% by weight Butyral resin (Sekisui Chemical Co., Ltd., S-REC BH-5) 28% by weight Methyl ethyl ketone 25% by weight Cyclohexanone 30% by weight Using the above components, an antistatic coating material and an antistatic plate were obtained in the same manner as in Example 5.

Comparative Example 1 Spherical white conductive powder (manufactured by Mitsubishi Materials Corp., W-10) 5% by weight 2-hydroxypropyl acrylate (10 mol%)-vinyl chloride (90 mol%) copolymer ( Sekisui Chemical Co., Ltd., Eslec E-HA) 25% by weight Methyl ethyl ketone 30% by weight Cyclohexanone 40% by weight Using the above components, an antistatic coating material and an antistatic plate were obtained in the same manner as in Example 1. .

[Comparative Example 2] Spherical white conductive powder (manufactured by Mitsubishi Materials Corp., W-10) 25% by weight 2-hydroxypropyl acrylate (10 mol%)-vinyl chloride (90 mol%) copolymer ( Sekisui Chemical Co., Ltd., S-REC E-HA) 20% by weight Methyl ethyl ketone 30% by weight Cyclohexanone 40% by weight Using the above components, an antistatic coating material and an antistatic plate were obtained in the same manner as in Example 1. .

Comparative Example 3 Spherical white conductive powder (manufactured by Mitsubishi Materials Corp., W-10) 15% by weight Acetal resin (Sekisui Chemical Co., Ltd., S-REC KS-5Z) 25% by weight Methylethylketone 30% by weight Cyclohexanone 30% by weight Using the above components, an antistatic coating material and an antistatic plate were obtained in the same manner as in Example 5.

[Comparative Example 4] Spherical white conductive powder (manufactured by Mitsubishi Materials Corporation, W-10) 25% by weight Butyral resin (manufactured by Sekisui Chemical Co., Ltd., S-REC BH-5) 20% by weight Methylethylketone 25% by weight Cyclohexanone 30% by weight Using the above components, an antistatic coating material and an antistatic plate were obtained in the same manner as in Example 5.

With respect to the antistatic plates thus obtained in Examples and Comparative Examples, performance evaluations regarding surface resistivity, coating adhesion and surface stain resistance were performed according to the following methods. The results are shown in Table 1.

[Surface resistivity] It was measured according to JIS K-6911.

[Coating Adhesion] It was evaluated according to JIS K-5400. The numbers in the table represent (the number of crosses that did not peel off / the total number of crosses).

[Surface Contamination Resistance] The degree of black streaks when rubbed with a steel round bar was evaluated.

○: No black streak △: Light black streak occurred ×: Clear black streak

[Table 1] [Storage stability] Further, in order to evaluate the storage stability of the coating composition, an acid having a carboxyl group was added to the antistatic coating compositions of Examples 1 to 3 above to prepare a coating composition for 1 month after the production of the coating composition. The degree of sedimentation of the conductive potassium titanate whiskers was examined. The results are shown in Table 2.

[0051]

[Table 2]

[0052]

According to the first aspect of the present invention, the conductive powder for exhibiting conductivity is changed from the conventional spherical particles to the acicular alkali metal whiskers. As a result, the conductive effect can be obtained with a smaller amount of mixture as compared with the conventional example, and the surface contamination resistance can be improved.

Next, according to the second aspect of the present invention, the conductive alkali metal titanate whiskers are used in an amount of 3 based on the total amount of the coating material.
By containing it in a proportion of ˜20% by weight, the production cost can be reduced without lowering the antistatic property, and
It is possible to more effectively improve the easiness of stains on the surface of the coating film.

Next, according to the third aspect of the present invention, an acid having a carboxyl group is further contained in a proportion of 0.2 to 2% by weight with respect to the total amount of the coating material, whereby the conductive alkali metal titanate whiskers are prepared. The dispersibility can be improved and sedimentation can be prevented, and even if the paint is stored for a long time after production, the conductive alkali metal titanate whiskers are not likely to sediment, and the storage stability of the paint can be improved.

Further, according to the invention of claim 4, the antistatic coating composition according to any one of claims 1 to 3 is applied, and the antistatic property is excellent and the stain resistance of the coating film surface is improved. Therefore, it is possible to provide an antistatic molded product with reduced manufacturing cost.

Claims (4)

[Claims] 1. An antistatic coating material containing a hydroxyl group-containing binder resin, a conductive alkali metal titanate whisker, and an organic solvent as main components. 2. The antistatic coating material according to claim 1, wherein the conductive alkali metal titanate whiskers are contained in a proportion of 3 to 20% by weight based on the total weight of the coating material. 3. The antistatic agent according to claim 1, further comprising an acid having a carboxyl group in an amount of 0.2 to 2% by weight based on the total amount of the coating material. paint. 4. An antistatic molded article formed by molding a laminate obtained by applying a predetermined amount of the antistatic coating composition according to claim 1 on a substrate and drying the coating. .