JPS60219266A - Antistatic paint and film - Google Patents

Abstract

PURPOSE:To provide paint which can effectively impart antistatic properties to floors, walls, ceiling, etc. when applied thereto, by dispersing electrically conductive zinc oxide (or tin oxide), ascorbic acid (derivative), etc. in a binder soln. CONSTITUTION:100pts.wt. electrically conductive zinc oxide (or tin oxide) (A) (particle size; 1mu or below) and 0.05-5pts.wt. ascorbic acid (or optical isomer, or a reducing derivative such as 5-0-methylascorbic acid) and/or reducing sugar (derivative) (e.g. aldose) (B) are dispersed in a binder (C) (e.g. polyvinyl alcohol or polyacrylic acid) to obtain an antistatic paint. The paint is applied to a substrate and dried to form a coating film of 0.2mm. or below in thickness, whereby antistatic properties can be effectively imparted to the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paint that is applied to floors, walls, ceilings, etc. of hospitals, electronics factories, chemical laboratories, etc. to prevent static electricity, and a film using this paint.

In recent years, with the rapid spread of electronic equipment, IC1LSI
There is also a significant increase in demand for electronic components such as ultra-LSIs.

In production factories and assembly factories for these electronic components, attempts are being made to make the floors, walls, ceilings, etc. of the production site conductive in order to eliminate static electricity and charge. In other words, if the floor surface becomes electrically charged due to the frictional contact of workers' footwear, or if the walls or ceiling become electrically charged due to indoor airflow, this static electricity may discharge to electronic components and damage them. This is because it becomes a cause of difficulty in removing dust. Taking the case of a dry paint film as an example, the surface resistance value effective for preventing static electricity is generally 1.
It is said to be 0' to 109Ω.

In addition, highly flammable chemicals and solvents are often used in hospital operating rooms and chemical laboratories, so in order to prevent fires and explosions, the floors must be made conductive to discharge static electricity that inevitably occurs. It is hoped that this will happen. On the other hand, if the resistance is excessively reduced during conductivity, electric shock may occur, so it is said that the surface resistance value of the dry coating film is desirably about 10' to 10' Ω. By the way, the United States N.F.P.A.
(National Fire Protection
As5ocation) standard, 2L5X10'
~lXl0'Ω.

In addition, a wide variety of antistatic applications are possible, such as meter display glass, television cathode ray tubes, clean room window glass, and semiconductor packaging materials.

Conventionally, conductive powders and conductive polymers have been used to prevent or remove static electricity. However, metals such as nickel and aluminum have problems with oxidation, precious metals such as silver are too expensive to use, and carbon black is black and has strong humidity dependence, so it is almost ineffective in low humidity environments. . As described above, the reality is that there is no inexpensive and fully satisfactory material for preparing conductive paints.

The present inventors focused on conductive zinc oxide, which is a white powder and is available at a relatively low price, and considered dispersing it in a binder solution to make an antistatic paint. In order to obtain the target resistance value with a paint, the ratio of conductive zinc oxide to the binder must be increased, resulting in the conductive zinc oxide being exposed on the paint film surface and reducing the strength of the paint film. Due to insufficient amount, peeling was likely to occur. Moreover, conductive tin oxide, which is difficult to realize with conductive zinc oxide when the target resistance value is 10'Ω or less, is about io~5 times as expensive as conductive zinc oxide, and there are cost constraints.

In view of the current situation, the present inventors have carried out extensive research and have found that when the following component φ) or component (C) is mixed with conductive zinc oxide or tin oxide, which is component (a), conductive The present invention was completed based on the knowledge that the resistance of the coating film was significantly improved and the resistance value of the coating film surface was reduced.

Φ) Component; Ascorbic acid, its optical isomer or a derivative thereof having reducing properties (C) Component; Reducing saccharide or its derivative Conductive zinc oxide contains a small amount of aluminum, gallium,
Adding impurity gold maple equivalent to tin as a doping agent,
It is a NW semiconductor obtained by firing, and can be obtained with various particle sizes and resistance values by appropriately selecting processing conditions such as the type and amount of doping agent, temperature, and time.

The same applies to conductive tin oxide, and its performance is generally determined by using antimony as a doping agent and controlling the processing conditions of the six vertebrae.

These conductive zinc oxides and tin oxides are effective in improving conductivity because the finer the particle size, the better the mutual contact within the coating film. It is desirable that it be less than Sμ. Particularly, fine powder having a particle size of o or iμ or less is useful because a transparent coating film can be obtained.

The conductive zinc oxide and tin oxide mentioned above are
R1! When R1 molecules are adsorbed to the surface, conduction electrons are driven inside, resulting in a decrease in electrical conductivity. In the present invention, as a result of blending component (b) such as ascorbic acid or component (C) with RD of reducing sugars into the paint, the electrical conductivity improves.The reason for this is that component (b) or (C) #i adsorbed on the surface of the seedlings! , and at the same time, component (b) or component (C) is reduced to (a).

This is thought to be due to the fact that as a result of adsorption to the surface of the component, charge transfer occurs between the component (a) and the component (b) or component (C) adsorbed to the surface.

Furthermore, when a reducing substance such as phosphite or hypophosphite is added to the metallic copper powder and copper compound as a conductive paint used to form circuits on printed wiring boards, the conductive effect can be improved. Are known. Since the paint used for forming these circuits is mainly composed of metallic copper powder, its unique color tone limits its uses. Further, phosphites and the like reduce and precipitate the copper content in the copper compound as metallic copper, and the precipitated copper fills the gaps between particles of the metallic copper powder, resulting in improved conductivity. Therefore, phosphite,
Sulfites, thiosulfates, etc. are not suitable for semiconductor materials such as conductive zinc oxide and tin oxide, which are component (a) of the present invention.
Does not produce conductivity improvement effect.

To explain the (mono) component used in the present invention, ascorbic acid is a strongly reducing substance having an enediol group represented by L-7 scorbic acid [the following general formula (I)], and its optical isomer Erythorbic acid [the following general formula (I
f) Along with ()), it increases the conductivity of conductive zinc oxide and tin oxide as described above. Similarly, as reducing ascorbic acid derivatives, mainly 1 of general formula (I) is used.
．． It refers to reaction derivatives at the 4, 5, and 6 positions, such as ether derivatives such as 5-0-methylascorbic acid, and ester derivatives such as ascorbic acid-6-
Examples include phosphoric acid esters such as phosphoric acid, sulfuric acid esters such as ascorbic acid-6-sulfuric acid, and organic acid esters such as 6-0-acetylascorbic acid.In addition, amine derivatives such as scorbamic acid, amidine derivatives, metal Examples include substances in which an enediol group (the following general formula (II)) remains, such as sodium ascorbate, which is a derivative of a salt or a basic salt.

-C=C- Also, one of the oxy groups of the enediol group shown in the general formula
Derivatives having one or two substituted with amino groups, thiol groups, or imino groups are also effective without impairing reducing properties. Regarding erythorbic acid, which is an optical isomer of ascorbic acid, derivatives similar to those described above have the same effect and are effective in the present invention.

On the other hand, the reducing sugars or derivatives thereof that are component <c> include reducing trisaccharides such as meltose, lactose, and melbiose, aldose-based glycolaldehyde, glucose, xylose, galactose, arabinose, mannose, etc., ketose-based nofructose, Examples include sorbose, dihydroxyacetone, etc., 2-ketoaldonic acid-based 2-ketogluconic acid, and uronic acid-based glucuronic acid. In particular, aldose-based, ketose-based, and uronic acid-based materials have strong reducing properties and have a remarkable effect of improving conductivity.

The blending ratio of component (b) and component (C) to component (a) is 10 parts by weight or less, preferably 0.005 to 5 parts by weight, per 100 parts by weight of component (a). 0.0
If the amount is less than 0.5 parts by weight, the effect of improving conductivity is small, and if it exceeds 5 parts by weight, the conductivity tends to decrease. (b)
Component or component (C) is usually added at the time of dispersing component (a) or when preparing and mixing the paint.
It may be mixed with other ingredients.

On the other hand, whether the binder of the paint is water-based or organic solvent-based,
Further, the specific binder to be used is mainly selected depending on the situation and environment of the object to be coated.

In aqueous systems, polyvinyl alcohol, methyl cellulose,
Examples include water-soluble binders such as hydroxyethyl cellulose, carboxymethyl cellulose, starch, and modified starch, and emulsion-based binders such as acetic acid-vinyl acrylic, acrylic acid, styrene-butadiene, and polyester. In addition, polymer electrolytes such as sodium polystyrene sulfonate and sodium polyacrylate having binding strength may be used as the binder.

Examples of the organic solvent type include acrylic acid, styrene, silicone resin, polyester resin, polyurethane resin, alkyd resin, and epoxy resin.

The present invention is not limited to the above-mentioned binders;
Two or more buildings may be mixed and used as appropriate.

In addition, if necessary, auxiliary agents, inorganic pigments, dyes, dispersants, ultraviolet absorbers, etc. are added to prepare the paint.

The blending ratio of component (a) and binder will vary depending on the target resistance value and strength of the coating film, but if there is too much binder, the distance between components (a) will become wider and the resistance will increase.
Usually, the weight ratio is 40 (60 to 952).The paints thus obtained are used in bars and sprays.

It is applied to ceilings, walls, wallpaper, floors, etc. that require conductive treatment using a doctor, blade, low-length hair, etc. Also, for small items, a surface coating is formed by dipping. be done.

Further, by applying the above-mentioned paint to a synthetic resin film, an antistatic film that can be used extremely easily can be obtained. The film used as the support in this case may have a thickness of several inches, but from the viewpoint of processability, it is generally desirable to use a thin film of 0.2 W or less.

In particular, the antistatic film obtained by coating a transparent resin film with a paint containing conductive tin oxide as the component (a) is obtained by selecting fine particles of tin oxide and controlling the coating amount. By adjusting the amount to a small amount, it is possible to manufacture transparent products.

As described above, according to the present invention, a paint comprising (a) at least one ff component and (b) at least one ff- component or (e) component dispersed in a binder can be applied. The advantage is that the surface resistance of the dried coating film obtained by this process is extremely low. Therefore, costs can be reduced by reducing the amount of coating, and if the amount of coating is the same, the ratio of the binder can be increased to improve the strength of the dried coating film. Furthermore, the paint film obtained with a paint containing conductive zinc oxide with an average particle size of about 0.2μ is white, and in the case of conductive tin oxide, an ultra-fine powder gives a slightly grayish transparent coating. Powder particles larger than about 0.1 μm form a white coating. Therefore, it is easy to adjust the color by adding dyes and pigments as appropriate after considering the target resistance value.

Furthermore, the antistatic film using the above-mentioned paint has the above-mentioned features as is, and can be cut into any shape and size depending on the intended object, making it easy to use. This antistatic film can be applied as long as the object is approximately flat. In particular, transparent antistatic films can be used as they are by pasting them on clean room windows and meter display glass.
profit Note that parts in the description mean parts by weight.

[Comparative Example 1] Conductive zinc oxide (
70 parts of saturated polyester resin (manufactured by Hakusui Chemical Co., Ltd., average particle size 0.2μ) and saturated polyester resin (Vylon 20SS, manufactured by Toyobo Co., Ltd.).

30% (solid content concentration) were mixed in advance and dispersed for 20 minutes using an attritor to obtain a paint. This paint was applied onto a hard vinyl chloride floor tile using a wire parser so that the dried paint film had a thickness of 20 μm, and after drying and solidification, the resistance value of the paint film surface was measured.

The surface electrical resistance was measured by placing two electrodes at a distance of 910 R and measuring the resistance between them.

[Example 1] 0.7 m of fructose was added to the paint of Comparative Example 1,
It was well dispersed and made into a paint. A coating film was formed on a floor tile in the same manner as in Comparative Example 1 except that this coating material was used, and its surface resistance value was measured.

[Comparative Examples 2 and 3] Paints were prepared with the same solid proportions of conductive zinc oxide and binder, and a coating test was conducted.

The same procedure was carried out except that the paint of Example 1 was used.

[Comparative Example 4] 100 parts of the same conductive zinc oxide as in Example 1 was dissolved in advance and mixed with 400 parts of a styrene-butadiene copolymer (Cariflex TR-1102 manufactured by Shell Chemical Co., Ltd.) having an fc of 20% and 82%, and the mixture was mixed with an attritor. After dispersing for 15 minutes, a paint was obtained.

This paint was applied onto the floor tiles using a wire bar so that it would have a coating thickness of 12 μm after drying, except that in Comparative Example 4, 1 part of dihydroxyacetone was added prior to the attritor treatment. The paint was obtained in the same manner. A coating test was conducted in the same manner as in Comparative Example 1 using this paint.

[Comparative Example 5] 100 parts of the same conductive zinc oxide as in Example 1 and 400 parts of a 2.518 degree Celsius methyl celseed solution were mixed thoroughly and then dispersed with an attritor for 40 minutes.

Got the paint. This paint was applied onto coated paper using a wire bar so that the dried coating film had a thickness of 6 μm and 11 μm, respectively. The surface resistance value was measured.

[Example 5-■ to 5-■] In Comparative Example 5, galactose,
xylose, melipiose, or glucuronic acid at 0.1
A paint was prepared in the same manner, except that 100% of the above was added and the dispersion treatment was carried out using an attritor. Comparative Example 5 using these paints
A coating film similar to that was obtained and its surface resistance value was measured.

The dried coating films obtained in the above Examples and Comparative Examples were all white. The test results are summarized in a table.

It can be seen from the above table that by adding component (e) to the paint, the surface resistance value of the resulting white dry paint film is significantly reduced. Therefore, in each example, in order to obtain a relatively low surface resistance value, that is, a surface resistance value equal to that of the corresponding comparative example, it is possible to increase the binder ratio in the paint; A stronger dry coating can be obtained than in the example.

[Comparative Example 6] 100 parts of 411L tin oxide (T-1.Sb-doped product manufactured by Mitsubishi Metals, particle size 0.1μ or less) was mixed with water-dispersed polyester resin (MD-1200 manufactured by Toyobo, 34% solid content concentration). ) was added and dispersed for 30 minutes using an attritor to obtain a paint. This paint was applied onto a 27 μm thick polyester film using a wire coater to form a dry coating film of 2 μm thickness to obtain an antistatic film. The surface electrical resistance of the coating of this film was 1.3×10'Ω.

[Example 6] 15 parts of ascorbic acid was further added to the paint in Comparative Example 6, and was well dispersed to form a paint.

Using this coating, it was coated on a polyester film in the same manner as in Comparative Example 6 to obtain an antistatic film f.

The surface electrical resistance of the coating film obtained by this method was 6.5.
When the film was pasted on the display glass of a measuring instrument, an excellent antistatic effect was obtained. In addition, when looking at the paint stage, the viscosity was higher and the film forming property was better than that of the paint of Comparative Example 6.

Claims (1)

[Scope of Claims] (Li) It is characterized by being made by dispersing in a binder solution at least one of the following components (a) and at least one component (b) or (C) as essential components. Antistatic paint. (a) Component; conductive zinc oxide or conductive tin oxide; (b) component; ascorbic acid, its optical isomer or a derivative thereof having reducing properties; (C) component; reducing saccharide or Derivatives thereof (2) (a)
The antistatic paint according to claim 1, characterized in that 0.005 to 5 parts by weight of component (b) or component (C) is blended per 100 parts by weight of component. (3) Apply a paint consisting of at least one of the following components (a) and at least one component (b) or (C) as essential components dispersed in a binder solution to a synthetic resin film. An antistatic film that is characterized by a special process. (a) Component; Conductive zinc oxide or conductive tin oxide (b) Component; Ascorbic acid, its optical isomer or a derivative thereof having reducing properties (C) Component; Reducing saccharide or its derivative (4) The paint The antistatic agent according to claim 3, wherein is a paint containing 0.005 to 5 parts by weight of component (b) or component (C) per 100 parts by weight of component (a). Film for. (5) The charging device according to claim 3 or 4, wherein the component (a) is a powder with a particle size of 0.1 μm or less, and the synthetic resin film is transparent. Prevention film.