JP4767317B2 - Coating liquid and coating method - Google Patents

Description

  The present invention relates to a coating solution and a coating method useful for surface modification of various articles.

  Conventionally, various types of plastic products (in the present invention, “plastic” means both “thermoplastic resin” and “thermosetting resin”) are used in large quantities. These plastic molded products include films, sheets, and various three-dimensional shaped articles. Similarly, a large amount of articles having various shapes are used for metal molded products, glass molded products, rubber molded products, leather molded products, woodwork products, and paper products.

  Plastic molded products have the advantage of being excellent in various physical properties such as ease of molding, ease of coloring, electrical insulation, weather resistance, etc., but on the other hand, the surface is superior to glass or metal. Are inherently soft materials, and thus have many drawbacks such as poor surface scratch resistance and gas barrier properties. In particular, with respect to the improvement of scratch resistance and gas barrier properties, a technique for forming a hard film made of a hard resin paint (hard coat paint) or a gas barrier vapor-deposited film made of aluminum or metal oxide on the surface of a plastic molded product is known. ing.

Most of the methods for improving the surface scratch resistance and gas barrier property are to form a functional layer such as a hard coat layer or a vapor deposition layer made of a material different from the plastic molded product on the surface of the plastic molded product. Is the content. Therefore, a problem remains in the adhesion between the plastic molded product and the functional layer formed on the surface thereof. For example, by forming a hard hard coat layer or gas barrier layer on the surface of a plastic molded article with a UV / electron beam curable hard coat paint or a paint containing polysilazane, the surface scratch resistance or gas barrier layer of the plastic molded article is formed. However, there is a problem in the adhesion between the surface of the plastic molded product and the hard coat layer or gas barrier layer, and the hard coat layer or gas barrier layer is whitened or peeled off due to bending of the molded product. In addition, the method using a polysilazane paint requires a high temperature for film formation, and is difficult to apply to a plastic molded product having low heat resistance. In addition, various problems remain in surface modification of glass and metal molded products (Patent Documents 1 and 2).
JP 2006-89654 A Japanese Patent Laid-Open No. 2003-183016

  Accordingly, an object of the present invention is to provide a coating liquid and a coating method which give excellent properties to the surface of an article such as a plastic molded product, a metal molded product, a glass molded product, a rubber molded product, a leather molded product, a woodwork product or a paper product. That is.

The above object is achieved by the present invention described below.
1. A poly ( alkyl ) silazane compound (hereinafter simply referred to as “ polyalkylsilazane ” or “component A”) and perhydropolysilazane (hereinafter also referred to as “component B”) are the sum of these two. As a coating liquid (hereinafter referred to as “first coating liquid”), which is dissolved in an inert organic solvent at a concentration of 1 to 40% by mass.

2. Furthermore, a first coating liquid (hereinafter referred to as “second coating liquid”) containing a hydroxyl group-containing oil or fat, a hydroxyl group-containing fatty acid or an ester thereof (hereinafter sometimes simply referred to as “C component”).

3 . Applying a coating solution of the present invention to the surface of the article, the article a composite layer comprising the reaction product of a silica or the silica and component C is a reaction product of component A and component B and water A method for coating an article, characterized in that the article is formed on the surface layer of the article.

  The coating liquid of the present invention can be repeatedly applied to various molded article surfaces in a short time, and even if it is formed into a thick film of 1 to 10 μm or more and bent, it can be peeled off from the surface of the object to be coated. There is no. In a preferred embodiment, the hardness of the film can be 6-9H or more in terms of pencil hardness, and has excellent film formability, flexibility, impact resistance, and adhesion.

  In film formation, a composite layer containing silica and / or a reaction product of silica and C component is formed in the surface layer portion of various molded articles by leaving or adding water without treatment at a particularly high temperature. The surface layer portion is a mixed composite layer of the constituent material of the molded product and silica and / or a reaction product of silica and C component. The surface layer portion of a molded product such as plastic, rubber, leather, paper or the like is integrated with the mixed composite layer, and the composite layer does not peel off even if the molded product is bent. Moreover, in the case of a metal molded product, high adhesion was recognized also in the surface layer part by causing each component to react with the oxide film on the surface.

Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention.
[First coating solution]
The main components of the first coating liquid of the present invention are an A component, a B component and an inert organic solvent. Examples of the component A include at least one selected from hexamethyldisilazane, octamethylsilazane, cyclotetrasilazane, and tetramethyldisilazane. These A components can be obtained from the market and used. Particularly preferred is hexamethyldisilazane available from Shin-Etsu Chemical Co., Ltd. under the trade name HMDS3.

The B component used in the present invention is a compound composed only of silicon, nitrogen and hydrogen, is an inorganic polymer not containing an organic component such as carbon, and is composed of-(SiH ₂ NH) -units. Yes. These B components are marketed under the registered trademark “AQUAMICA” under the product numbers NN110, NN310, NL110A, NL120A, NL150A, NL160A, NP110, NP140, SP140, and UP140. It can be obtained and used as a solvent solution. Particularly preferred is product number NL120A in a dibutyl ether solution.

  The first coating liquid of the present invention is obtained by dissolving the A component and the B component in an organic solvent. The organic solvent to be used is not particularly limited as long as it is inactive with respect to the above-mentioned compounds, but from the viewpoint of moderate swelling, volatility and environmental hygiene on the surface of plastic molded articles, etc. For example, it is preferably at least one selected from dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether and limonene.

  The A component and the B component dissolved in these organic solvents are preferably in a mass ratio of A: B = 30 to 90: 70-10 when the total amount of both is 100 parts by mass. If the amount of component A used is too small, the film will crack when a thick film of 2 μm or more is formed. On the other hand, if the amount of component A used is too large, it is difficult to form a thick composite layer. Moreover, when the pencil hardness of 6H or more is requested | required by the film | membrane formed, it is preferable to set it as the mass ratio of A: B = 30-70: 70-30.

  The total concentration of the A component and the B component in the first coating liquid of the present invention is 1 to 40% by mass. If the concentration is too low, a large amount of coating solution must be used to form a composite layer having a desired film thickness. On the other hand, if the concentration is too high, the components react with moisture in the air, and the coating solution Is not preferred because it gels easily. In addition, the coating liquid of this invention may contain various additives, such as a hydrolysis catalyst. Further, it is possible to form a film by adding nano-level metal particles.

[Second coating liquid]
In the second coating liquid of the present invention, the first coating liquid further contains a C component. The component C used in the present invention includes hydroxy fatty acid having a hydroxyl group in its structure, which is a constituent chemical substance such as castor oil, and glycerin esters thereof, castor oil fatty acid and castor oil fatty acid which are the main hydrolysis components of castor oil. Derivatives such as ricinoleic acid and its esters, which are the main components, or cholesterol-containing fats and oils having hydroxyl groups such as lanolin fats and oils, and lanolin fatty acids and esters thereof that are hydrolysed thereof. The alcohol component of the ester is preferably a lower alcohol having 1 to 5 carbon atoms. Particularly preferred component C is castor oil and lanolin oil. The second coating solution is prepared by dissolving in an inert organic solvent such as dibutyl ether at a concentration of 1 to 40% by mass as the total amount of the A component, B component and C component. The C component may further contain urushiol.

  By using the C component, the flexibility of the coating formed is increased, and the possibility of cracking or cracking is greatly reduced even if the coating is bent. In addition, the leveling property of the coating agent is improved, the coating suitability is improved, and a thick film can be formed. In addition, the water repellency and smoothness of the formed film are also improved. The reason for such an improvement effect is unknown, but the C component does not elute even if the film is solvent-extracted. Therefore, the C component is chemically reacted with the A component or the B component by its hydroxyl group. I think that the. It is also considered that C component is saponified to produce fatty acid monochrylide, diglyceride, or glycerin, and these products are chemically reacted with A component or B component.

  In the above, the usage ratio of A component and B component is as above-mentioned, and the usage ratio of C component has the preferable range of 10-50 mass parts per 100 mass parts of total amounts of A component and B component. The reason for the use ratio of the A component and the B component is as described above, but for the C component, when the use ratio of the C component is less than the above range, the above improvement effect is low, while the use ratio of the C component. If the value exceeds the above range, the hardness of the coating film to be formed decreases.

[Third coating solution]
The third coating liquid of the present invention is obtained by dissolving the A component and the C component in an inert organic solvent such as dibutyl ether at a concentration of 1 to 40% by mass as the total of these two components. . By using the C component in addition to the A component, a coating having higher flexibility than the coating formed by the A component alone is formed, and the possibility of cracking or cracking is greatly reduced even if the coating is bent. . In addition, the leveling property of the coating agent is improved, the coating suitability is improved, and a thick film can be formed. In addition, the water repellency and smoothness of the formed film are also improved. Although the reason for such an improvement effect is unknown, it is considered to be due to the same reason as the second coating solution.

  The use ratio of the A component and the C component in the third coating liquid is a mass ratio of A: C = 50 to 90: 50-10 when the total amount of the A component and the C component is 100 parts by mass. Preferably there is. When the use ratio of the C component is less than the above range, the improvement effect is low. On the other hand, when the use ratio of the C component exceeds the above range, the hardness of the formed film is reduced.

[Fourth coating solution]
Further, the fourth coating liquid of the present invention is obtained by dissolving the B component and the C component in an inert organic solvent such as dibutyl ether at a concentration of 1 to 40% by mass as the total of these two components. . By using the C component in addition to the B component, a coating with higher flexibility than the coating formed by the B component alone is formed, and the possibility of cracking or cracking is greatly reduced even if the coating is bent. . In addition, the leveling property of the coating agent is improved, the coating suitability is improved, and a thick film can be formed. In addition, the water repellency and smoothness of the formed film are also improved. Although the reason for such an improvement effect is unknown, it is considered to be due to the same reason as the second coating solution.

  The use ratio of the B component and the C component in the fourth coating liquid is a mass ratio of B: C = 50 to 90: 50-10 when the total amount of the B component and the C component is 100 parts by mass. It is preferable. When the use ratio of the C component is less than the above range, the improvement effect is low. On the other hand, when the use ratio of the C component exceeds the above range, the hardness of the formed film is reduced.

  In the coating method of the present invention, the coating liquid of the present invention is applied to the surface of an article, the component A and / or the component B is hydrolyzed to silica, or these silica and component C are reacted with each other. A composite layer containing transparent silica and / or a reaction product of silica and C component is formed on the surface layer. The article to be coated by the coating method of the present invention is not particularly limited. Articles that are particularly effective are plastic molded products and metal molded products, and other examples include glass molded products, rubber molded products, leather molded products, woodwork products, and paper products.

  Examples of plastic molding materials include polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyamide (nylon), vinyl chloride resin, acrylic resin, silicone resin, fluorine resin, polyimide resin, polysulfone resin, and the like. Known thermosetting resins such as thermoplastic resins, epoxy resins, melamine resins, phenol resins, unsaturated polyester resins, and the like can be mentioned, and are not particularly limited. Examples of the shape of the plastic molded product made of these materials include films, sheets, plates, and other various three-dimensional molded products.

  Examples of the material of the metal molded product include, but are not limited to, iron, aluminum, duralumin, stainless steel, copper, gold, silver, titanium, nickel, and the like. Examples of the shape of the metal molded product made of these materials include a plate, a rod, and other three-dimensional molded products.

The application method of the coating liquid of the present invention on the surface of the above various articles is not particularly limited, and an application method suitable for the shape of the article to be coated, for example, spray method, dipping method, brush coating method, roll coating method, gravure coating Method, flexo method, ink jet method and the like. The coating amount is not particularly limited, but the coating amount may be determined in accordance with the surface performance required for the article to be coated. Generally, it is 0.1-100 g / m < ² > in conversion of solid content, Preferably it is 1-20 g / m < ² >. If the coating amount is less than 0.1 g / m ² , a surface composite layer having sufficient characteristics will not be formed. On the other hand, if the coating amount exceeds 100 g / m ² , the composite layer will be over-quality. The transparency of the chemical layer may be lost.

  A prominent feature of the coating method of the present invention is that no special heating is essential for curing the coating layer applied as described above. Although the formation of the composite layer is promoted by heating the coating layer, the curing of the coating layer proceeds even when left in the air after coating. Curing by standing is a reaction with water due to the absorption of moisture in the air as the solvent of the coating solution evaporates. The curing rate after standing is, for example, a finger hardness of 2 hours and a pencil hardness of 6 in about 2 days. It becomes a film having a hardness of ˜9H or more. Although the reaction with water is promoted by heating, a temperature of 120 ° C. or lower is sufficient for heating. It should be noted that heating at a temperature exceeding 120 ° C., for example, 300 ° C. has no problem and has heat resistance up to 1,000 ° C.

  As described above, the coating method of the present invention is completed, and a composite layer containing silica or a reaction product of silica and component C is formed on the surface layer of various molded articles. It was confirmed by an impact deformation test that the adhesiveness of the composite layer was particularly strong and had followability to deformation of the coated surface.

  The surface of various molded products obtained as described above has an inorganic property similar to that of silica, and the pencil hardness is improved to 6H to 9H or higher regardless of the type of constituent material of the molded product. As a result, the scratch resistance and gas barrier properties are remarkably improved. Moreover, even if the surface-treated molded product is repeatedly subjected to a bending test, the surface composite layer does not change, and no peeling or whitening (due to cracks) is observed. These facts suggest that the layer formed by the coating liquid of the present invention is a composite layer in which the reaction product of silica or silica and component C is chemically bonded to the molded article substrate. .

  Further, since the surface of the composite layer is silica-rich, the surface has high hardness and insulation, and is excellent in heat resistance, corrosion resistance, gas barrier properties, and contamination resistance. In particular, a coating film containing a C component can form a thick film, and is a composite film of silica, which is an inorganic substance, and the C component, which is an organic substance, and therefore has excellent water repellency.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following text, “part” and “%” are all based on mass.
[First coating solution]
Example 1
10% dibutyl ether solution of perhydropolysilazane (trade name Aquamica NL120A, diluted product manufactured by Clariant Japan KK) (liquid a) and hexamethyldisilazane (trade name HMDS3 manufactured by Shin-Etsu Chemical Co., Ltd.) The first coating liquid (Nos. 1 to 9) of the present invention was obtained by mixing the 10% solution (liquid b) with the ratio shown in Table 1 below.

Comparative Examples 1-2
Liquid a alone in Example 1 was designated as Comparative Example 1 (coating liquid No. 10), and liquid b alone was designated as Comparative Example 2 (coating liquid No. 11).

Example 2
The coating liquids (Nos. 1 to 10 ) of the examples and comparative examples were charged into spray cans. On the other hand, an iron plate having a size of 20 cm × 10 cm and a thickness of 2 mm was prepared, and the coating solution (No. 1 to 10 ) was spray-applied on the surface of the iron plate at a rate of about 30 g / m ² from the spray can. After heating to a temperature of 70 ° C. to remove most of the solvent, it was left for 48 hours in an atmosphere at a temperature of 25 ° C. and a relative humidity of 60%. The contact angle with water of the resulting 1 0 kind of iron (Nanba1～1 0), surface hardness (pencil hardness), recoatability, were examined bending peel resistance, impact deformation resistance and film-forming properties below The results in Table 2 were obtained.

  In the above, the contact angle of water is measured with a contact angle meter, the surface hardness is the pencil hardness according to JIS regulations, and the overcoatability is the surface condition when the same amount of coating agent is applied after drying with the touch. Observed and examined for transparency and reactivity. Bending peelability was also examined by visual observation. For impact deformation, a DuPont impact deformation test was adopted. Film formation was performed by visual observation.

Example 3
Each of the coating liquids (No. 1 to 11) was charged into a spray can. On the other hand, a transparent acrylic plate having a size of 20 cm × 20 cm and a thickness of 1 mm was prepared, and the coating liquid (No. 1 to 11) was spray-applied to the surface of the acrylic plate from the spray can at a rate of about 20 g / m ² . After heating to a temperature of 45 ° C. to remove most of the solvent, it was left in an atmosphere at a temperature of 80 ° C. and a relative humidity of 80% for 48 hours. When the transparency, surface hardness, overcoatability, bending peelability, impact deformation property and film formability of the 11 kinds of acrylic plates obtained were examined, the results shown in Table 3 below were obtained.

  In the above, the transparency was observed with the naked eye, and it was examined whether or not the transparency was equivalent to that of the untreated acrylic board. Other performances are the same as those in the second embodiment.

[Second coating agent]
Example 4
The first coating liquid No. 1-No. 9 was mixed with a commercially available castor oil dibutyl ether 10% solution in the proportions shown in Table 4 below to obtain second coating solutions (No. 2-1 to 2-5).

Example 5
Transparency, surface hardness, overcoatability, bending of five types of acrylic plates (2-1 to 2-5) produced in the same manner as in Example 3 except that the second coating liquid of Example 4 was used. When the peelability, impact deformability and film formability were examined, the results shown in Table 5 below were obtained.

[Third coating solution]
Example 6
The said b liquid and the dibutyl ether 10% solution of the said castor oil were mixed in the ratio of the following Table 6, and the 3rd coating liquid (No.3-1 to 3-5) was obtained.

Example 7
Transparency, surface hardness, overcoatability, bending of five types of acrylic plates (3-1 to 3-5) produced in the same manner as in Example 3 except that the third coating liquid of Example 6 was used. When the peelability, impact deformability and film formability were examined, the results shown in Table 7 below were obtained.

[Fourth coating solution]
Example 8
The said a liquid and said dibutyl ether 10% solution of castor oil were mixed in the ratio of the following Table 8, and the 4th coating liquid (No. 4-1 to 4-5) was obtained.

Example 9
Transparency, surface hardness, overcoatability, bending of five types of acrylic plates (4-1 to 4-5) produced in the same manner as in Example 3 except that the fourth coating liquid of Example 8 was used. When the peelability, impact deformability and film formability were examined, the results shown in Table 9 below were obtained.

Example 10
In the above Examples 4 to 9, instead of castor oil, castor oil fatty acid, castor oil fatty acid methyl ester, ricinoleic acid, ricinoleic acid methyl ester, lanolin, lanolin fatty acid, lanolin fatty acid methyl ester were used in the same manner. Similar results were obtained as in Examples 4-9.

  According to the present invention described above, it is possible to provide a coating solution and a thick film coating method useful for surface modification of various articles.

Claims (10)

A coating liquid comprising a poly ( alkyl ) silazane compound and perhydropolysilazane dissolved in an inert organic solvent at a concentration of 1 to 40% by mass as the total of these two. When the total amount of the poly ( alkyl ) silazane compound (A) and the perhydropolysilazane (B) is 100 parts by mass, the blending ratio of both is A: B = 30 to 90: 70-10. The coating liquid according to claim 1.   Furthermore, the coating liquid of Claim 1 containing a hydroxyl-containing fat or oil, a hydroxyl-containing fatty acid, or its ester. The content of the hydroxyl group-containing oil or fat, the hydroxyl group-containing fatty acid or its ester is 10 to 50 parts by mass per 100 parts by mass of the total amount of the poly ( alkyl ) silazane compound (A) and perhydropolysilazane (B). The coating liquid as described in 1. Poly (alkyl) silazane compound, the coating liquid according to claim 1 is hexamethyldisilazane or tetramethyl dicyanamide Raza down.   The coating liquid according to claim 3, wherein the hydroxyl group-containing oil or fat or the hydroxyl group-containing fatty acid or ester thereof is castor oil, castor oil fatty acid, castor oil fatty acid ester, ricinoleic acid, ricinoleic acid ester, lanolin, lanolin fatty acid or lanolin fatty acid ester.   The coating liquid according to claim 1, wherein the inert organic solvent is at least one selected from dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, and limonene. 4. The coating liquid according to claim 1 or 3 is applied to the surface of an article, and the reaction product of poly ( alkyl ) silazane compound and / or perhydropolysilazane and water or silica and a hydroxyl group-containing oil or hydroxyl group. A method for coating an article, comprising forming a composite layer containing a reaction product with a fatty acid or ester thereof in a surface layer portion of the article. The method for coating an article according to claim 8 , wherein the complexing reaction is performed at a temperature of 120 ° C. or less. The method for coating an article according to claim 8 , wherein the article is a plastic molded article, a metal molded article, a glass molded article, a rubber molded article, a leather molded article, a woodwork article, or a paper product.