JP3233742B2 - Antistatic coating composition for plastics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for an antistatic coating for plastics.

[0002]

2. Description of the Related Art Plastic products having low hygroscopicity and high electrical insulation are susceptible to damage due to static electricity.
For example, in the processing and use of various plastics molded articles, films, and the like, the adhesion of dust and dust and the occurrence of electric discharge may cause the plastics products to become dirty, or to cause deterioration or damage to the functions of the products. In order to prevent such an electrostatic failure, a conductive film is formed on the surface of plastics to prevent charging. Also,
In many cases, the coating is required to be transparent so that the texture and color of the plastics are not lost.

The following are known as such conductive and transparent coatings. Surfactant paint applied. Inorganic salts such as lithium chloride and magnesium chloride, and ion conductive substances such as polymer electrolytes containing carboxylic acid groups and sulfonic acid groups,
A film formed of a composition dispersed in a film-forming substance such as a synthetic resin or silicate. For example, Japanese Patent Publication No. 58-3586
No. 7 discloses an antistatic coating composition in which an acrylic polymer is used as a film-forming substance and lithium nitrate is blended as an ion-conductive substance, which is coated with a polyester film. Also, Journal of the A
American Ceramic Society, 484-486, Vol. 72, No. 3, (1
989) includes phosphomolybdic acid (H ₃ PMo ₁₂ O ₄₀ · 29H
Disclosed is a solution obtained by dissolving ₂ O) in a solution of a hydrolyzate of tetraethoxysilane and forming a film on a glass plate or a stainless steel plate. A composition is formed by dispersing conductive fine particles such as powder of a metal such as silver, nickel, copper, tin or the like or an oxide thereof in a film-forming substance such as an acrylic resin, a polyester resin, or tetraethoxysilane. Filmed. For example, Japanese Patent Publication No. 63-33778 discloses that a conductive fine powder of antimony-containing tin oxide having a particle size of 0.2 μm or less is contained at a ratio of 50 to 70% by weight based on the solid content of a coating material. It is disclosed that paints provide an antistatic coating for plastic products.

[0004] However, the above-mentioned coating film has the drawback that not only the surface resistance is as high as 10 ¹⁰ Ω / □ or more, but also the surface resistance value increases with time.

[0005] The above-mentioned coating has the disadvantage that conventionally used ion-conductive substances have a reduced conductivity when the humidity is low, and that sufficient antistatic properties cannot be obtained.
For example, in Japanese Patent Publication No. 58-35867, the surface resistance is as high as about 10 ¹⁰ Ω / □ at 50% relative humidity, and the antistatic performance is insufficient. In addition, phosphomolybdic acid (H ₃ PMo ₁₂ O ₄₀
When 29H ₂ O) is dissolved in a solution of a hydrolyzate of tetraethoxysilane, when applied on a plastic plate to form a film, cracks occur in the film, and the film cannot be applied to plastic products. .

In the above-mentioned film, it is necessary to increase the concentration of conductive fine particles in the film in order to obtain a sufficient antistatic property. For this reason, there is a drawback that haze is generated based on light scattering by the fine particles and transparency is impaired.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to easily form a transparent, high antistatic, crack-free coating on plastic products. An object of the present invention is to provide a composition for antistatic coating obtained.

[0008]

The mixture (a) used in the present invention comprises a silane compound A represented by the following general formula [I] and Si (OR) ₄ ... [I] And a silane compound B represented by the general formula [II]. Y _n Si (OR ¹ ) _4-n・ ・ ・ [II]

In the formula, R and R ¹ each represent an alkyl group having 1 to 5 carbon atoms. When the number of carbon atoms increases, the stability of the coating composition decreases and the long-term storage stability deteriorates. Is limited to 1 to 5. Examples of R and R ¹ include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group and a tert-butyl group. Y is an organic group other than the OR group and the OR ¹ group, and examples thereof include a hydrocarbon group, a glycidoxyalkyl group, an epoxycyclohexylalkyl group, a (meth) acryloyloxyalkyl group, and a mercaptoalkyl group. Examples of the hydrocarbon group include an alkyl group, a substituted alkyl group, an allyl group, a vinyl group, a phenyl group, and a naphthyl group. Also,
n is an integer of 1 to 3.

The compound represented by the general formula [I] includes
For example, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-iso-
Examples include propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, and the like.

The compound represented by the general formula [II] includes
When n is 3, for example, monomethyltrimethoxysilane, monomethyltriethoxysilane, monomethyltri-
n-propoxysilane, monomethyltri-iso-propoxysilane, monomethyltri-n-butoxysilane,
Monomethyltri-sec-butoxysilane, monomethyltri-tert-butoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4 epoxycyclohexyl) Examples include ethyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and mercaptopropyltrimethoxysilane.

When n is 2, for example, dimethyldimethoxysilane, dimethyldiethoxysilane,
n-propoxysilane, dimethyldi-iso-propoxysilane, dimethyldi-n-butoxysilane, dimethyldi-sec-butoxysilane, dimethyldi-tert-
Butoxysilane, diethyldiethoxysilane, ethylvinyldiethoxysilane, ethylphenyldiethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and the like.

When n is 1, for example, trimethylmonomethoxysilane, trimethylmonoethoxysilane, trimethylmono-n-propoxysilane, trimethylmono-
iso-propoxysilane, trimethylmono-n-butoxysilane, trimethylmono-sec-butoxysilane, trimethylmono-tert-butoxysilane, triethylethoxysilane, diethylvinylethoxysilane, diethylphenylethoxysilane, γ-glycidoxypropylethyl Methylethoxysilane and the like can be mentioned.

As the silane compound A and the silane compound B, the compounds within the ranges defined above may be used alone or in combination of two or more. Among many combinations of the silane compound A and the silane compound B constituting the mixture of the present invention, tetraethoxysilane is used as the silane compound A, and methyltrimethoxysilane or γ-glycidoxypropyltrimethoxysilane is used as the silane compound B. The following combinations are particularly preferred.

In the present invention, the molar ratio of the silane compound A to the silane compound B is limited to 80:20 to 20:80. When the amount of the silane compound A increases, cracks easily occur in the coating, and when the amount decreases, the coating becomes opaque.

The fluorosulfonic acid (b) used in the present invention is represented by the chemical formula FSO ₃ H. The fluorosulfonic acid (b) is used in an amount of 0.0 to 1 mol of the mixture (a).
It is added at a rate of 01 to 0.2 mol. When the amount of the fluorosulfonic acid (b) decreases, sufficient conductivity for preventing static electricity cannot be imparted to the coating, and when the amount increases, the composition for antistatic coating forms a white precipitate and a uniform composition cannot be obtained. The preferable addition amount is 0.08 to 0.5 to 1 mol of the mixture (a).
It is in the range of 2 moles.

The organic solvent (c) used in the present invention is not particularly limited as long as it is compatible with the mixture (a) and water (d) and dissolves the fluorosulfonic acid (b). Instead, for example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and butyl alcohol, ketones such as acetone and methyl ethyl ketone, and tetrahydrofuran are exemplified, and methyl alcohol, ethyl alcohol, and isopropyl alcohol are particularly preferable. These may be used alone or in combination of two or more.

The organic solvent (c) is mixed with the mixture (a)
It is added at a ratio of 5 to 100 mol per 1 mol.
When the amount of the organic solvent (c) decreases, the coating composition is difficult to be uniformly mixed, resulting in a non-homogeneous composition. When the organic solvent (c) increases, the solid content concentration of the coating composition becomes too low. It cannot obtain a good antistatic ability. The preferable addition amount is in the range of 5 to 30 mol per 1 mol of the mixture (a).

The water (d) used in the present invention is added for the hydrolysis of the mixture (a). Water (d) is added in a ratio of 1 to 30 mol per 1 mol of the mixture (a). When the amount of water (d) is small, sufficient hydrolysis is unlikely to occur, and when it is large, compatibility with the coating composition is poor. The preferred amount of addition is 3 to 1 mol of the mixture (a).
10 moles.

If necessary, an acid may be added to the antistatic coating composition of the present invention as a catalyst for hydrolyzing the silane compound. The amount of the acid added may be 0.01 to 5% by weight in the water added to the composition at the above ratio. If the ratio is less than this, the effect as a catalyst cannot be expected, and if the ratio is too large, the coating becomes non-uniform. The acid is not particularly limited, and any of an inorganic acid and an organic acid can be used, and examples thereof include hydrochloric acid and sulfuric acid.

The composition of the antistatic coating composition for plastics of the present invention is as described above, but a hydrophilic polymer such as polyethylene glycol may be added to further improve the conductivity. Further, in order to improve the film forming property, a cellulose derivative such as methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, or hydroxypropylcellulose may be contained. For the same purpose, colloidal oxides such as silica sol, alumina sol, and zirconia sol may be contained.

The method for producing the antistatic coating composition for plastics of the present invention is not particularly limited. For example, a method in which the above-mentioned constituent materials are mixed together, or a method in which a specific constituent material is divided. After mixing, a method in which the remaining constituent materials are added and mixed is exemplified. As a method of dividing and mixing, for example, a silane compound A and a silane compound B are mixed, an organic solvent is added to the mixture, and after mixing and stirring, water containing fluorosulfonic acid is added and stirred and mixed. The hydrolysis / polycondensation reaction proceeds to obtain the coating composition.

The antistatic coating composition for plastics of the present invention can be produced by the above-mentioned ordinary simple method, and can be used in the same manner as the conventional silicone-based coating composition.

The antistatic coating composition for plastics of the present invention is applied to a plastics product and dried to form an antistatic coating. The application method is not particularly limited, for example, brush, spray coat, dip coat, spin coat, roll coat,
An application method such as flow coating is used.

The drying method is not particularly limited, and may be natural drying at room temperature or heating and drying. After drying, high-temperature heat treatment may be performed if necessary. For example, the composition for an antistatic coating is coated on the surface of a plastics product by the method described above, air-dried at room temperature, and then cured at a temperature of 60 ° C to 150 ° C to form an antistatic coating. The obtained plastics product is obtained.

The plastics coated with the antistatic coating composition is not particularly limited.
Examples include plastics such as polycarbonate, acrylic resin, polyvinyl chloride, polystyrene, polyester, and polyurethane. Also, the shape of the product is not particularly limited, and examples thereof include a molded product and a film.

The coating obtained from the antistatic coating composition of the present invention has high transparency and high conductivity because fluorosulfonic acid is uniformly present in an ion state in the coating. In addition, even if the material is hardly rubbed with a hard material such as steel wool, it is hardly damaged by scratches, and the appearance is not easily deteriorated by scratches.

The present invention 2 uses a silane compound (a ₁ ) represented by the following general formula [III] instead of the mixture (a) used in the antistatic coating composition for plastics of the present invention. Is done.

Embedded image In the formula, R ² represents an alkyl group having 1 to 5 carbon atoms. When the number of carbon atoms increases, the stability of the coating composition decreases and the long-term storage property deteriorates. Limited.
Examples of R ² include a methyl group, an ethyl group, n- propyl group, iso- propyl, n- butyl group, sec- butyl group, a tert- butyl group. R ³ is an alkylene group having 1 to 5 carbon atoms. Y ¹ represents a hydrocarbon group, and examples thereof include an alkyl group and a substituted alkyl group. Y ² represents an organic group having an amino group, and examples thereof include an amino group itself and a substituted amino group in which a hydrogen atom of an amino group is substituted with an aminoalkyl group.
m is 0, 1 or 2.

The compound represented by the general formula [III] includes
For example, γ-aminopropylmethyldiethoxysilane,
γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl)- γ-aminopropylmethyldimethoxysilane,
N, N-bis [3- (trimethoxysilyl) propyl]
Ethylenediamine and N, N-bis [3- (methyldimethoxysilyl) propyl] ethylenediamine. Of these, N- (β-aminoethyl) -γ-
Aminopropyltrimethoxysilane and γ-aminopropyltrimethoxysilane are particularly preferred.

The fluorosulfonic acid (b) used in the present invention 2 is added in a ratio of 0.0001 to 0.1 mol based on 1 mol of the silane compound (a ₁ ). When the amount of the fluorosulfonic acid (b) decreases, sufficient conductivity for preventing static electricity cannot be imparted to the coating, and when the amount increases, the composition for antistatic coating forms a white precipitate and a uniform composition cannot be obtained.
The preferred amount is, the silane compound (a ₁₎ is 0.05 to 0.1 mols per 1 mol.

The organic solvent (c) used in the present invention 2 is
There is no particular limitation as long as it is compatible with the silane compound (a ₁ ) and water (d) and dissolves the fluorosulfonic acid (b). For example, methyl alcohol, ethyl alcohol, isopropyl alcohol, Examples thereof include alcohols such as butyl alcohol, ketones such as acetone and methyl ethyl ketone, and tetrahydrofuran. Particularly preferred are methyl alcohol, ethyl alcohol, and isopropyl alcohol. These may be used alone or in combination of two or more.

The organic solvent (c) is added at a ratio of 5 to 100 mol based on 1 mol of the silane compound (a ₁ ). When the amount of the organic solvent (c) decreases, the coating composition is difficult to be uniformly mixed, resulting in a non-homogeneous composition. When the organic solvent (c) increases, the solid content concentration of the coating composition becomes too low. It cannot obtain a good antistatic ability. The preferred amount is, the silane compound (a ₁₎ is in the range of 5 to 30 mol relative to 1 mol.

The water (d) used in the present invention 2 is added for hydrolysis of the silane compound (a ₁ ). Water (d) is 1 to 3 with respect to 1 mole of the silane compound (a ₁ ).
It is added at a rate of 0 mol. When the water (d) is low,
Sufficient hydrolysis does not easily occur, and if it is too large, the compatibility with the coating composition is poor. A preferable addition amount is 3 to 10 mol per 1 mol of the silane compound (a ₁ ).

The antistatic coating composition of the present invention 2 may further contain an acid as a catalyst for hydrolyzing the silane compound, if necessary. The amount of the acid added may be 0.01 to 5% by weight in the water added to the composition at the above ratio. If the ratio is less than this, the effect as a catalyst cannot be expected, and if the ratio is too large, the coating becomes non-uniform.
The acid is not particularly limited, and any of an inorganic acid and an organic acid can be used, and examples thereof include hydrochloric acid and sulfuric acid.

The composition of the antistatic coating composition for plastics of the present invention 2 is as described above, but a hydrophilic polymer such as polyethylene glycol may be added to further improve the conductivity. Further, in order to improve the film forming property, the general formula [I] used in the present invention of claim 1 is used.
Or a silane compound B represented by the general formula [II] may be added. For the same purpose, a cellulose derivative such as methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, or hydroxypropylcellulose may be contained. For the same purpose, colloidal oxides such as silica sol, alumina sol, and zirconia sol may be contained.

The method for producing the antistatic coating composition for plastics of the present invention 2 is not particularly limited. For example, a method in which the above-mentioned constituent materials are mixed together, or a method in which a specific constituent material is divided After mixing, the remaining constituent materials are added and mixed. As a method of dividing and mixing, for example, the silane compound (a ₁ ) and the above-mentioned silane compound A to be added as necessary
Alternatively, one or two or more silane compounds B are mixed, an organic solvent is added to the mixture, and after mixing and stirring, water containing fluorosulfonic acid is added and stirred and mixed.
The hydrolysis / polycondensation reaction proceeds to obtain the coating composition.

The coating obtained from the antistatic coating composition of the present invention 2 has high transparency and high conductivity since fluorosulfonic acid is uniformly present in an ion state in the coating. In addition, even if the material is hardly rubbed with a hard material such as steel wool, it is hardly damaged by scratches, and the appearance is not easily deteriorated by scratches.

[0038]

Embodiments of the present invention will be described below. The methods for evaluating the properties of the antistatic coating composition shown in the results are as follows.

(1) Crack test The obtained antistatic coating composition was added to a 50 × 100 mm (2 m thick)
m) polycarbonate substrate (Lexan sheet 9034 manufactured by Asahi Glass Co., Ltd.) was immersed and pulled up at a speed of 300 mm / min.
After drying at room temperature for 60 minutes, the composition was cured at 110 ° C. for 60 minutes to form an antistatic film on the substrate to prepare an evaluation sample, and the presence or absence of cracks was examined by visual observation. (Judgment criteria) ：: No crack is observed. X: Cracks are observed.

(2) Surface Resistance Using the obtained antistatic coating composition, an evaluation sample prepared in the same manner as in the above-described crack test was prepared.
Using STACK TR-3 manufactured by Tokyo Electronics Co., Ltd., the surface resistance was measured and evaluated by a two-terminal method in an atmosphere with a relative humidity of 50%.

(3) Light Transmittance The light transmittance of an evaluation sample prepared in the same manner as in the above-described crack test using the obtained antistatic coating composition was measured using an untreated polycarbonate substrate as a reference. Was evaluated using a spectrophotometer UV-3101PC manufactured by Shimadzu Corporation in the range of 400 to 700 nm.

(4) Pencil Hardness Using the obtained antistatic coating composition, an evaluation sample prepared in the same manner as in the above-described crack test was used.
It was measured and evaluated according to IS K5400.

(5) Polyethylene terephthalate (PE)
T) Film Adhesion Test Using the obtained antistatic coating composition, the surface of an evaluation sample prepared in the same manner as in the above-described crack test was rubbed with a woolen fabric, and the PET film was finely cut into 1 × 3 mm ( Approach to a distance of about 1cm on the
The state of adhesion of the ET film was evaluated according to the following criteria. (Judgment criteria) ：: Does not adhere to the surface at all. Δ: Slightly adheres to the surface. ×: Many adhere to the surface.

(6) Abrasion resistance test Using the obtained antistatic coating composition, the surface of an evaluation sample prepared in the same manner as in the above-described crack test was reciprocated 10 times with steel wool # 0000. The sample was rubbed and the scratch resistance of the sample surface was evaluated according to the following criteria. (Judgment Criteria) し て も: Even if strongly rubbed, the surface is not damaged at all. Δ: The surface is slightly scratched when strongly rubbed. X: The surface is markedly scratched even by weak friction.

The methods for producing the antistatic coating compositions of Examples and Comparative Examples and the results of evaluation of the physical properties of the compositions are shown below. The meanings of the abbreviations used in Tables 1 and 3 below are as follows: It is. Silane compound S1: Tetraethoxysilane S2: Methyltrimethoxysilane S3: γ-glycidoxypropyltrimethoxysilane S4: N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane S5: γ-aminopropyltrimethoxy Silane Y1: Methyl alcohol

(Examples 1 to 4) A predetermined amount of methyl alcohol shown in Table 1 was supplied to a glass beaker, and a predetermined amount of silane compound A and silane compound B shown in Table 1 were added. The mixture was stirred at a stirring speed of 800 rpm to obtain an alcohol solution of the silane compound.

The obtained alcohol solution was as shown in Table 1.
A predetermined amount of water shown in Table 1 containing a predetermined amount of fluorosulfonic acid was added, and the mixture was further stirred at room temperature for 3 hours at a stirring speed of 800.
The mixture was stirred at rpm to obtain an antistatic coating composition. Using the obtained antistatic coating composition, each physical property was measured based on the above-mentioned measuring methods, and the results are shown in Table 2.

(Comparative Examples 1 and 2) An antistatic coating composition was obtained in the same manner as in Example 1 using the silane compound A and the silane compound B shown in Table 1, methyl alcohol, fluorosulfonic acid and water. . Using the obtained antistatic coating composition, based on the above measurement method, to measure each physical property,
The results are shown in Table 2. When the above components were mixed, the composition for antistatic coating of Comparative Example 1 became cloudy and a precipitate was formed, so that a film could not be formed.

[0049]

[Table 1]

[0050]

[Table 2]

(Examples 5 to 9) A predetermined amount of methyl alcohol shown in Table 3 was supplied to a glass beaker, and a predetermined amount of aminosilane or silane compound B shown in Table 3 was added.
The mixture was stirred at room temperature for 3 hours at a stirring speed of 800 rpm to obtain an alcohol solution of a silane compound.

Table 3 shows the obtained alcohol solution.
A predetermined amount of water shown in Table 3 containing a predetermined amount of fluorosulfonic acid was added, and the mixture was further stirred at room temperature for 3 hours at 800 rpm.
The mixture was stirred at rpm to obtain an antistatic coating composition. Using the obtained antistatic coating composition, various physical properties were measured based on the above-mentioned measurement methods, and the results are shown in Table 4.

(Comparative Examples 3 and 4) An antistatic coating composition was obtained in the same manner as in Example 5 using the aminosilane, methyl alcohol, fluorosulfonic acid and water shown in Table 3. Using the obtained antistatic coating composition, various physical properties were measured based on the above-mentioned measurement methods, and the results are shown in Table 4. The composition for antistatic coating of Comparative Example 3 was cloudy when the above components were mixed, and a precipitate was formed, so that a film could not be formed.

[0054]

[Table 3]

[0055]

[Table 4]

[0056]

The composition of the antistatic coating composition for plastics of the present invention is as described above, and a specific silane compound mixture, fluorosulfonic acid, an organic solvent and water are mixed in specific amounts. It is possible to easily form a transparent and highly antistatic crack-free coating on a product.

The composition of the antistatic coating composition for plastics of the present invention 2 is as described above. Since a specific amount of the specific aminosilane, fluorosulfonic acid, organic solvent and water is blended, the composition of the plastics product is used. It is possible to easily form a transparent, high antistatic effect and a crack-free film.

Continuation of the front page (56) References JP-A-55-34276 (JP, A) JP-A-55-99930 (JP, A) JP-A-48-55884 (JP, A) JP-A-63-193971 (JP) JP-A-3-287663 (JP, A) JP-A-62-232157 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 183/04

Claims (2)

(57) [Claims] (A) a silane compound A represented by the following general formula [I], and a silane compound B represented by the following general formula [II]: Si (OR) ₄ ... ^{_{consists, Y n Si (oR 1)}} 4-n ··· [II] ( wherein, R and R ¹ are an alkyl group having 1 to 5 carbon atoms, Y
Is OR and OR ¹ except organic radical, n is an integer of 1 to 3)
The molar ratio of the silane compound A and the silane compound B is 80:20.
２０20: 80, (b) fluorosulfonic acid, (c) organic solvent and (d) water, wherein the molar ratio of mixture (a), (b), (c) and (d) is 1 : 0.
001 to 0.2: 5 to 100: 1 to 30. An antistatic coating composition for plastics. Wherein (a ₁₎ and the silane compound represented by the following general formula [III], [Chemical Formula 1] (Wherein, R ² is an alkyl group having 1 to 5 carbon atoms, R ³ is an alkylene group having 1 to 5 carbon atoms, Y ¹ is a hydrocarbon group, Y ² is an organic group having an amino group, and m is 0.1 or 1. Or 2) (b) fluorosulfonic acid, (c) an organic solvent and (d) water, wherein (a ₁ ), (b), (c) and (d)
Is 1: 0.0001 to 0.1: 5 to 100:
A composition for an antistatic coating for plastics, which is 1 to 30.