JP2003003124A - Coating composition having prevented electrification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating having reduced staining property and an antistatic coating economically, and to provide a coating composition easily handleable and having prevented electrification. SOLUTION: The paint composition having prevented electrification is obtained by adding an inorganic salt having deliquescence or an inorganic salt hydrate having deliquescence to an aqueous coating or a solvent-soluble coating without deteriorating appearance (color, transparency, etc.), of the coating and without changing properties as a coating.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antistatic coating composition. Furthermore, the present invention relates to a coating composition which is prevented from being charged by utilizing the deliquescent property of an inorganic salt hydrate. The coating material of the present invention is not limited to so-called coating material, but also to so-called coating agent used for surface coating.

[0002]

2. Description of the Related Art Paints have a long history, and in the past, most of them were solvent-based. Recently, in this field as well, consideration for the environment has become necessary, and in particular, the problem of VOC (volatile organic substances) has been highlighted, and the rise of water-based paints has been remarkable, and this trend is expected to continue in the future.

However, the oldest and still unsolved problem is
How long the state of application can be maintained, that is, the durability of the paint is a problem. Prevention of static electricity, which is one of the causes, is also an important issue. That is, as a cause of the stain, it is considered that dust in the air, an oily substance or the like adheres to the surface of the coating film due to static electricity. In order to solve this problem, for example, hydrophilic paints and antistatic paints have been proposed. In the former hydrophilic paint, for example, a hydrophilic group such as OH is present on the surface, whereby water in the air is adsorbed and a thin film of water is formed. In the latter antistatic coating, a means such as applying a conductive substance or an antistatic substance to the surface or mixing the antistatic substance into the coating is taken. However, the principle of adding the latter antistatic substance is as follows.
As in the case of the hydrophilic paint, moisture in the air is adsorbed on the surface to form a thin film of water. By forming this water thin film,
It becomes easier to remove dirt by washing with water, and it is said to be particularly effective for raindrop contamination.

The problem in this case is that the addition causes
That is, the color, transparency, and physical properties of the base material are not significantly changed, and that the base material has excellent antistatic properties. A surface resistivity is a numerical value representing the antistatic property. That is, the larger the surface resistivity, the easier the charging becomes. Therefore, it is necessary to reduce the surface resistivity in order to sufficiently prevent charging.

According to the conventional method, it has been difficult to reduce the surface resistivity to 10 ⁷ Ω or less without significantly changing the appearance and physical properties of the base coating material. Even if possible, it was difficult to carry out industrially, with a significant cost increase.

[0006] Conventionally, many means have been proposed for preventing electrostatic charge on the paint surface. For example, addition or coating of an antistatic agent, addition or coating of a conductive substance, incorporation of a conductive substance into powder coating, improvement of conductivity of polymer itself, hydrophilic coating, and the like. However, in consideration of the effect and economic efficiency of any of the means, both have advantages and disadvantages, and it is difficult to say that they are satisfactory means.

There is a so-called super-durable paint that maintains the durability of the paint. For example, fluororesin paint, acrylic silicone paint, silicone emulsion paint and the like. But these are expensive,
It is not easy to use anywhere. Therefore,
An object of the present invention is to economically improve the durability of commonly used paints by simple means.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a paint stain,
In order to prevent deterioration, by utilizing the deliquescent property of an inorganic salt or a hydrate of an inorganic salt to prevent electrification, it is intended to provide a paint in which the generation of static electricity on the surface is prevented. It has the following configuration. (1) An antistatic coating composition comprising 1 to 50 parts by weight of a deliquescent anhydrous inorganic salt or a deliquescent inorganic salt hydrate to 100 parts by weight of a base polymer. (2) Anhydrous inorganic salts are CaCl ₂ , MgCl ₂ , AlCl ₃ , Ca (N
o ₃ ) ₂ , Mg (NO ₃ ) ₂ , Al (NO ₃ ) ₃ , Na ₂ CO ₃ , Na ₂ SiO ₃ , Na ₂ HPO ₄
Or NaH ₂ PO ₄ and the inorganic salt hydrate is selected from hydrates of these salts (1)
A coating composition having an antistatic property as described in 1. (3) The above (1), wherein the coating composition is a water-based coating composition.
Alternatively, the antistatic coating composition according to (2). (4) The coating composition as described in any one of (1) to (3) above, wherein the coating composition is a solvent-based coating composition. (5) The antistatic coating composition according to the above (4), which uses an inorganic salt hydrate. (6) The coating composition according to any one of (1) to (5) above, which is an antistatic coating.

The present invention will be described in detail below. Paint is
They are roughly classified into solvent-based paints and water-based paints, and the antistatic composition obtained in the present invention is effective for both of them. However, the present composition is most effective in the case of the water-based paint. In the case of water-based paint, it is possible to add it in the form of anhydrous inorganic salt. The reason is that even if it is added as an anhydrous inorganic salt, it is converted into a hydrate and incorporated into the polymer as a hydrate.

There is a so-called high-solid paint as a paint, which aims at quick-drying by reducing the amount of the solvent as much as possible, and such a paint also depends on whether the solvent is water-based or solvent-based. , And is included in either the water-based paint or the solvent-based paint in the present invention.

In the present invention, it is an object of the present invention to prevent electrification and prevent contamination by adding an inorganic salt having a deliquescent property or a hydrate thereof to a generally used paint. However, it goes without saying that the antistatic paint itself is included in the present invention. Generally, the antistatic coating is used for the purpose of preventing static electricity by applying it to a place where static electricity is disliked, and is widely used in various industrial fields. However, the coating composition of the present invention is excellent. Due to its antistatic property, the property that does not impair the appearance (color, transparency, etc.) of the substrate, the small effect on physical properties, and the economical efficiency (small cost increase), it is often used in various industries as described above. It has the potential to be used in applications.

[0012] Conventional antistatic paints include, for example, fluffing on fibers and papermaking, winding of threads and fibers, poor folding, uneven thread prevention, prevention of screen clogging in the powder industry, plastics, and rubber. Quality deterioration due to dust adhesion in industry, prevention of electrostatic charge during processing, film, wrapping around machines in the photographic industry, prevention of quality deterioration, malfunction in electronic equipment industry, prevention of noise, electric shock, precision equipment industry It is used for various purposes such as prevention of quality deterioration due to dust adhesion in
It is sufficiently possible to use the coating composition of the present invention for such an application.

When added to a solvent-based paint, it is preferable that the salt hydrate to be added be ground as finely as possible and then atomized, but in the case of a water-based paint, this is not necessary. This is because, in the case of a solvent system, the added salt hydrate is present in the paint in the form of a solid, and therefore the atomization is performed in order to increase the antistatic effect and to reduce the influence on the appearance and physical properties. is necessary. The degree of atomization varies depending on the application, but generally the average particle size is 200 microns or less, preferably
100 microns or less is desired. However, in the case of a water-based paint, the added anhydrous inorganic salt or hydrate of an inorganic salt is taken into the polymer in a state of being dissolved in water, so that atomization is not necessary.

The amount of the anhydrous inorganic salt or inorganic salt hydrate added in the present invention is generally 0.5 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the base polymer. Is determined from the antistatic effect and the degree of influence on the substrate. For example, when it is desired to reduce the surface resistivity after drying to 10 ⁷ Ω, the addition amount as a salt hydrate is 5 to 20 parts by weight, and 10 ⁸ Ω to 10 parts by weight based on 100 parts by weight of the base polymer.
^In the case of ⁹ Ω, 1 to 10 parts by weight is sufficient. Even in the case of solvent-based paints, if the amount added is in this range, the color, transparency and physical properties of the base paint will not change significantly due to the addition of salt hydrate, but in the case of water-based paints the effect of addition will be Is extremely slight. In the case of a paint, there is a concern that the characteristics of the paint will be affected, but as shown in the examples, it is not so large.

As the salt to be added, any salt having deliquescent property and capable of forming a hydrate can be used, but the antistatic effect, the appearance (color, transparency, etc.) and physical properties of the base coating material can be used. Has less impact on the safety, safety, price, etc. of CaCl ₂ , M
gCl ₂ , AlCl ₃ , Ca (No ₃ ) ₂ , Mg (No ₃ ) ₂ , Al (No ₈ ) ₃ , Na ₂ C
O ₃ , Na ₂ SiO ₃ , Na ₂ HPO ₄ or NaH ₂ PO ₄ are particularly preferred. As mentioned above, it is of course possible to add these salts in the form of hydrates. However, in the case of a water-free paint, that is, a solvent-based paint, it is necessary to add the above inorganic salt as a hydrate. That is, CaCl ₂ 6H ₂ O, MgCl ₂ 6H ₂ O, AlCl ₃ 9
_{H 2 O, Ca (NO 8} ) 2 4H 2 O, Mg (NO 8) 2 6H 2 O, Al (NO 3) 3 9H 2 O, Na
₂ CO ₃ 10H ₂ O, Na ₂ SiO ₃ nH ₂ O, Na ₂ HPO ₄ 12H ₂ O or NaH ₂ PO ₄ 2H ₂
It is necessary to add it in the form of O (or 1H ₂ O).

According to the present invention, the surface resistivity can be easily lowered to 10 ⁷ Ω or less without significantly changing the appearance and physical properties of the base coating material. Further, it can be lowered to 10 ⁴ Ω or less depending on an appropriate combination of salt and polymer. The relationship between the decrease in the surface resistivity and the contact angle with water, and the relationship with the stain resistance are as revealed in many previous studies. That is, the decrease in the surface resistivity means the formation of a thin film of water, which leads to less generation of static electricity, which in turn means less stain on the surface.

In the present invention, the chemical structure of the polymer constituting the base coating material is not particularly limited. The added salt hydrate is
Since it is physically incorporated between polymer molecules, it exhibits an antistatic effect regardless of the chemical structure of the polymer.

In this method, it is easy to add fine particles of a salt hydrate in the case of a solvent type paint and to add an anhydrous inorganic salt or a salt hydrate in the case of a water type paint. The addition takes place, for example, in a product tank, but only with sufficient stirring. Also,
It is also possible to add the above anhydrous inorganic salt or inorganic salt hydrate to the paint delivered as a product. Generally, the above addition may be performed at room temperature. Heating may be used to promote mixing, but heating at 50 ° C. or lower is sufficient in this case as well. No special equipment is required for the addition. Suffice it to say, it only needs sufficient agitation.

One important feature of the present invention is its economics. The inorganic salts used in this method are extremely inexpensive. Therefore, considering the effect as the filler, the cost increase due to the addition is very small. Compared with the fact that conventional antistatic agents are considerably expensive, it can be said that they are extremely attractive in combination with their effects.

As the antistatic agent currently on the market,
As many as 400 kinds are known, but no inorganic substances are included in this. In the present invention, attention has been paid to the characteristics of inorganic substances that have not been used as antistatic agents, and it has been found that a surprising antistatic effect is exhibited.

In the coating composition of the present invention, the above-mentioned anhydrous inorganic salt or inorganic salt hydrate can be used in a solvent system, but the characteristics are more remarkably exhibited in an aqueous coating composition. That is,
The salt hydrate (anhydrous inorganic salt also turns into a hydrate) is taken into the polymer in a state of being dissolved in water. It was found by the present inventor that when taken in this state, it is very uniformly dispersed in the base material, the appearance and physical properties of the base material are hardly changed, and a large antistatic effect is exhibited. The invention was completed.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments and effects to be achieved by the present invention will be explained by the following examples, but the present invention is not limited to these examples.

[0023]

Example 1 Aqueous emulsion for styrene / acrylic paint, CaCl ₂ , MgCl ₂ , AlCl ₃ and its hydrate, CaCl 2.
The antistatic effect of ₂ 6H ₂ O, MgCl ₂ 6H ₂ O or AlCl ₃ 9H ₂ O was observed. The anhydrous inorganic salt or anhydrous salt hydrate is added to the emulsion at room temperature, and after sufficiently stirring, poured onto a Teflon substrate to form a film having a thickness of 0.03 mm from an applicator. After sufficiently drying at room temperature, the surface resistivity, charge voltage and half-life (applied voltage 10KV), and triboelectric charge of the film surface were measured (according to JIS L-1094). As a blank, a sample to which these salts or salt hydrates were not added was also prepared by the same method, the same measurement was performed, and the results were compared. The measurement is
It was performed under the conditions of 20 ° C. and 20% relative humidity. The appearance (color, transparency) and touch (softness, elasticity) of the sample after addition of the salt or salt hydrate were almost the same as those of the blank sample. The results are shown in Table 1. The addition amount in Table 1 is shown in parts by weight in terms of hydrate of the salt with respect to the base polymer in the emulsion.

[0024]

[Table 1]

[0025]

Example 2 A nitrate was added in place of chloride to the same styrene / acrylic coating emulsion as in Example 1 above. That is, Ca (No ₃ ) ₂ , Mg (No ₃ ) ₂ , Al (No ₈ ) ₃ and its hydrate Ca (NO ₃ ) ₂ 4H ₂ O, Mg (NO ₃ ) ₂ 6H ₂ O or Al (N
O _{3) 3} was added 9H ₂ O. The addition method, sample preparation method, measurement method and measurement conditions, and addition amount were all the same as in Example 1. The appearance and feel of the sample after addition were almost the same as those of the blank. The results are shown in Table 2.

[0026]

[Table 2]

[0027]

Example 3 The same styrene / acrylic coating emulsion as in Examples 1 and 2 was replaced by Na ₂ Co ₃ and Na ₂ SiO _{3 in place of} chloride (Example 1) and nitrate (Example 2). Or its hydrate was added. The addition method, sample preparation method, measurement method and measurement conditions, and addition amount were all the same as in Example and 2. The appearance and feel of the sample after addition was almost the same as that of the blank again. The results are shown in Table 3.
Shown in.

[0028]

[Table 3] The amount added in the table is the amount of salt or salt hydrate added (g) / weight of the coating material before addition.

[0029]

[Example 4] An acrylic resin paint for exteriors (manufactured by Dainippon Paint Co., Ltd.), which is a solvent-based paint, was obtained, and CaCl ₂ , MgC was added to this.
l ₂ , AlCl ₃ and their hydrates CaCl ₂ 6H ₂ O and MgCl ₂
6H ₂ O or AlCl ₃ 9H ₂ O was added and the antistatic effect was observed. That is, these salts or salt hydrates were finely atomized in a mortar (average particle size 60 microns), added to a paint, and sufficiently stirred at room temperature. The obtained coating material was applied onto a Teflon substrate and sufficiently dried at room temperature to form a film having a thickness of 0.03 mm. The surface resistivity, charging voltage, half-life (applied voltage 10 KV) and triboelectric charge of this film were measured under the conditions of 20 ° C. and 20% relative humidity (according to JIS L-1094). As a blank, a sample to which these salts or salt hydrates were not added was prepared by the same method, the same measurement was performed, and the results were compared. The results are shown in Table 4. The appearance and feel of the sample to which the above salt or salt hydrate was added were almost the same as those of the blank.

[0030]

[Table 4]

[0031]

[Example 5] The solvent-based paint used in Example 4 had Ca (NO ₃ ) ₂ 4H.
₂ O, Mg (NO ₃ ) ₂ 6H ₂ O, Al (NO ₃ ) ₃ 9H ₂ O, Na ₂ CO ₃ 10H ₂ O or Na ₂ S
iO ₃ nH ₂ O was added and its antistatic effect was observed. The preparation of the added sample, the adding method, the adding amount, the measuring method, and the measuring conditions are the same as in Example 4. The results are shown in Table 5 in comparison with the blank. Also in this example, the appearance and feel of the sample after addition were not different from those of the blank.

[0032]

[Table 5] The added amount is shown by the weight (g) of the added salt or salt hydrate with respect to the coating weight (g).

[0033]

Example 6 Ethylene / vinyl acetate copolymer resin paint (water-based emulsion paint, nonvolatile content 48%) was added to Ca (NO ₃ ) ₂ ,
Mg (NO ₃ ) ₂ , Al (NO ₃ ) ₃ and its hydrate Ca (NO ₃ ) ₂ 4H
₂ O, Mg (NO ₃ ) ₂ 6H ₂ O or Al (NO ₃ ) ₃ 9H ₂ O was added, and its antistatic effect and changes in the properties as a coating due to the addition were observed. The above anhydrous inorganic salt or inorganic salt hydrate is added to the coating material at room temperature, and after sufficiently stirring, it is applied on a glass substrate (film thickness 0.02 mm) and sufficiently dried at room temperature, and then the surface resistivity of the film surface, Charge voltage, half-life (applied voltage 10KV) and triboelectric charge were measured (according to JIS L-1094). The measurement was performed at 20 ° C. and 20% relative humidity. After that, the gloss retention (weather resistance test), coating film elongation, water contact angle, adhesion strength, pencil hardness, tensile strength, and bending strength of these samples were examined. The results are shown in Table 6 in comparison with the blank. The results are shown in Table 6.
Shown in.

[0034]

[Table 6]

[0035]

Example 7 Styrene / acrylic copolymer resin paint (aqueous emulsion, nonvolatile content 49%) was added to Ca (NO ₃ ) ₂ 4H ₂ O, Mg (N
O ₃ ) ₂ 6H ₂ O, Al (NO ₃ ) ₃ 9H ₂ O, Na ₂ CO ₃ 10H ₂ O or Na ₂ SiO ₃ nH
₂ O was added, and its antistatic effect and changes in the properties as a paint by addition were observed. The above inorganic salt hydrate is added to the paint at room temperature, and after sufficient stirring, it is applied on a glass substrate (film thickness
0.02 mm), after sufficiently drying at room temperature, the surface resistivity, charge voltage and half-life (applied voltage 10 KV) and triboelectric charge of the film surface were measured (JIS L-1094). Measured at 20 ° C and 20% relative humidity
I went there. Furthermore, these samples were examined for gloss retention (weather resistance test), coating film elongation, water contact angle, adhesion strength, pencil hardness, tensile strength and bending strength. What is the addition amount?
As in Example 6, it is an additive weight part (g) with respect to the coating material weight (g) before addition. The results are shown in Table 7 in comparison with the blank.

[0036]

[Table 7]

[0037]

[Example 8] Na ₂ HPO ₄ or NaH ₂ PO ₄ was added to a styrene / acrylic acid ester copolymer resin paint (water-based emulsion, non-volatile content 50%), and its antistatic effect and changes in properties as a paint by the addition. I saw. Add each inorganic salt hydrate to the paint at room temperature, stir it well, apply it on a glass substrate (film thickness 0.02 mm), and sufficiently dry it at room temperature, then the surface resistivity, charge voltage, half-life of the film surface. (Applied voltage 10 KV) and friction electrification voltage were measured (JIS L-1094). The measurement was performed at 20 ° C. and 20% relative humidity. In addition, for these samples,
Gloss retention (weather resistance test), coating film elongation, water contact angle, adhesion strength, tensile strength and bending strength were observed. The addition amount is the weight of the additive (g) with respect to the weight of the coating material (g) before the addition, as in Examples 6 and 7. Table 8 comparing results with blanks
Shown in.

[0038]

[Table 8]

[0039]

[Summary of Results] The following can be confirmed from Examples 1 to 9. I. It is obvious that the deliquescent inorganic salt hydrate prevents the paint surface from being charged. B. This antistatic effect is large, and the surface resistivity can be easily lowered to 10 ⁷ Ω or less, and it can be lowered to 10 ⁴ Ω or less by an appropriate combination of salt and polymer. C. The antistatic composition of the present invention is effective not only in water-based paints but also in solvent-based paints. However, in the case of a solvent system, it is preferable to add the salt hydrate to be added after atomizing it. D. In the case of a water-based paint, the effect remains the same whether an anhydrous inorganic salt or an inorganic salt hydrate is added. It is considered that this is because the anhydrous inorganic salt is converted into a hydrate and incorporated into the polymer. E. The appearance (color, transparency) of the base coating material is hardly impaired by the addition of the inorganic salt or its salt hydrate for the prevention of static electricity. F. The antistatic composition of the present invention exerts an effect irrespective of the chemical composition of the base coating material using the polymer.
It is considered that this is because the salt hydrate is physically incorporated into the polymer. G. The use of the composition significantly suppresses the charge on the paint surface, so that the water contact angle is greatly reduced and the stain resistance is significantly improved. J. The addition causes some changes in elongation, adhesive strength, tensile strength, bending strength, etc., but the changes are small and practically no problem.

[0040]

INDUSTRIAL APPLICABILITY In the present invention, by adding an inorganic salt having a deliquescent property to a polymer or a hydrate thereof,
The charging of the paint surface is significantly prevented, and as a result, the contact angle to water and the stain resistance are reduced. In addition, the addition of the inorganic salt or its hydrate hardly impairs the color, transparency, etc. of the paint, and does not significantly change the properties of the paint, so that there is practically no problem. Further, the addition of the inorganic salt and its hydrate does not economically increase the cost. It is extremely easy to add these salts or hydrates thereof, especially to water-based paints, and not only special equipment is required, but also addition just before coating is possible, and handling is extremely simple. . From these things, not only is it easily implemented as a measure to reduce the contamination of commonly used paints,
Due to its antistatic effect, it is expected to have a special application as an antistatic coating.

Claims (6)

[Claims] 1. A deliquescent anhydrous inorganic salt or a deliquescent inorganic salt hydrate is used per 1 part by weight of a base polymer.
A coating composition with antistatic property, characterized in that -50 parts by weight is added. 2. Anhydrous inorganic salt is CaCl ₂ , MgCl ₂ , AlCl ₃ , C
a (No ₃ ) ₂ , Mg (NO ₃ ) ₂ , Al (NO ₃ ) ₃ , Na ₂ CO ₃ , Na ₂ SiO ₃ , Na ₂ H
Has been selected from PO ₄ or NaH ₂ PO _4, inorganic salt hydrate is prevent charging of claim 1, characterized in that a member selected from the hydrates of these salts Coating composition. 3. The antistatic coating composition according to claim 1 or 2, wherein the coating composition is a water-based coating composition. 4. The antistatic coating composition according to claim 1, wherein the coating composition is a solvent-based coating composition. 5. The antistatic coating composition according to claim 4, wherein an inorganic salt hydrate is used. 6. The coating composition according to claim 1, which is an antistatic coating.