JPH0138419B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating composition capable of forming a coating film with high adhesion on the surface of molded products such as plastics and metals, which has excellent scratch resistance and abrasion resistance, and has good dyeability. . In general, plastic molded products and metal molded products such as aluminum and zinc have drawbacks such as being easily scratched and easily worn due to their low surface hardness. In order to improve these problems, a method of forming a coating film of a curable substance on the surface of the molded article has been carried out, and various coating compositions have been proposed for forming the coating film. For example, JP-A-53-78273, JP-A-48-55884
No. 4,027,073 discloses a coating composition comprising an alkyltrialkoxysilane or a mixture thereof with a tetraalkoxysilane or colloidal silica. However, the coating film obtained by heating and curing the coating composition after hydrolyzing it has excellent scratch resistance, but has poor adhesion to the surface of the molded product or poor flexibility of the coating film itself. Poor adhesion, peels and cracks in hot water. Therefore, a method of providing an undercoat layer (aminoacrylate type) when coating with the coating composition has been disclosed (Japanese Patent Application Laid-Open No. 53-138476), but although the adhesion is improved by this method, the resulting coated film is lacks smoothness, making it difficult to dye uniformly with, for example, disperse dyes. On the other hand, coating compositions containing epoxy group-containing organoalkoxysilanes and epoxy resins have excellent adhesion and dyeing properties, but have low surface hardness, and in order to increase this, a curing agent and a crosslinking agent are mixed in the coating composition. When this value is increased, the dyeability and adhesion, which were originally good, become poor. Therefore, the present inventors conducted extensive research to develop a coating composition that can form a coating film with excellent scratch resistance, abrasion resistance, and dyeability on the surface of plastic molded products with high adhesion. The present inventors have discovered that a coating film obtained from a coating composition containing a specific disilane compound containing a carbonate group as a constituent component satisfies all of these properties and has completed the present invention. That is, the present invention provides the general formula ...A disilane compound containing a carbonate group represented by (1) (wherein A is a 2-carbonate group-containing disilane compound whose main chain consists of at least 7 or more atoms in a straight chain)
Valid atomic group, R ¹ and R ² are the same or different alkyl groups or alkoxyalkyl groups, R ³ and R ⁴
are the same or different alkyl groups). The greatest feature of the present invention is that, as mentioned above, while conventional coating compositions have only a monosilane compound as a constituent component,
The point is that a disilane compound containing a carbonate group is used. Since this disilane compound has four alkoxy groups at both ends per molecule, the coat film formed by the polycondensation reaction of its hydrolyzate has a high crosslinking density and high surface hardness. It is thought that it has excellent scratch resistance and abrasion resistance, and also provides solvent resistance. In addition, since the structure has a certain distance between the functional groups between Si and Si,
It stains well with molded products, and since the coating film itself is elastic and has excellent flexibility, it can cope with the expansion and contraction of molded products due to heat, and exhibits excellent adhesion. Furthermore, since it has a carbonate group in its molecule, it has good dyeability with disperse dyes and can be easily dyed by ordinary dyeing methods. Hereinafter, the coating composition of the present invention will be explained in detail. In the disilane compound containing a carbonate group represented by general formula (1), R ¹ and R ² are the same or different alkyl groups or alkoxyalkyl groups,
An alkoxyalkyl group having 1 to 6 carbon atoms, especially 1 to 3 carbon atoms, or an alkoxyalkyl group having 1 to 6 carbon atoms, especially 1 to 3 carbon atoms bonded to an alkoxy group having 1 to 6 carbon atoms, especially 1 to 3 carbon atoms. suitable. Specifically, methyl group, ethyl group, propyl group, methoxyethyl group, etc. are common. Also, R ³ , R ⁴
are the same or different alkyl groups, preferably those having 1 to 4 carbon atoms. Specific examples include methyl group, ethyl group, and propyl group. A
is a divalent functional group containing a carbonate group and having a main chain of at least 7 or more atoms in a straight chain,
general formula (However, R is CH ₂ CH ₂ O or CH ₂ CH ₂ CH ₂ O
(where p is an integer from 0 to 4, q is 0 when p = 0, and 1 when p = 1 to 4) Specifically, is exemplified. These disilane compounds containing a carbonate group represented by the general formula (1) can be synthesized by various conventionally known methods. In other words, a compound that has a substituent with a double bond that can be added at both ends and also contains a carbonate group inside is subjected to a platinum catalyst.

[Formula] and/or

It can be synthesized by addition reaction of an alkoxysilane represented by the formula. Or instead of alkoxysilane,

[Formula] and/or

The chlorosilane represented by the formula may be subjected to an addition reaction, and then alkoxylated with an alcohol represented by R ¹ OH or R ² OH. The reaction conditions are not particularly limited, but the reaction may generally be carried out at normal pressure and a temperature of -20 to 160°C, if necessary, in a polar nonaqueous solvent such as benzene, toluene, dimethyl ether, or the like. Further, it is preferable to use platinum black as the platinum catalyst since a colorless and transparent product can be obtained. for example,
By reacting diethylene glycol bisallyl carbonate with diethoxymethylsilane under a platinum catalyst. is obtained. In the present invention, it is preferable that the coating composition containing the carbonate group-containing disilane compound as a constituent component hydrolyzes the disilane compound prior to coating the molded article. It is preferable to use it in a polycondensed form. Hydrolysis of the disilane compound may be carried out by adding and stirring a weakly acidic aqueous acid containing an inorganic substance such as hydrochloric acid or sulfuric acid or an organic substance such as formic acid or acetic acid. However, due to the heat generated by hydrolysis, polycondensation may proceed excessively, resulting in solidification of the reaction solution or shortening the life of the prepared coating composition. Therefore, the disilane compound is used in an appropriate solvent, preferably so that the concentration of the disilane compound in a completely hydrolyzed and polycondensed state (hereinafter referred to as converted concentration) is 30% by weight or less. After mixing, it is desirable to hydrolyze gradually. In addition, it ensures that the hydrolysis reaction and subsequent partial polycondensation reaction proceed,
In order to obtain reproducible and stable coating film performance, it is desirable to leave the reaction solution to ripen, and the appropriate period for this is about 1 to 2 days at room temperature. The coating composition of the present invention may contain alcohol, alkoxy alcohol, unreacted water, or solvent produced by the above-mentioned hydrolysis during use, but after hydrolysis, the above-mentioned components are removed by heating and/or under reduced pressure. The solvent can also be replaced by removal by distillation and subsequent addition of a suitable solvent. The final concentration of the coating composition is preferably 20 to 40% by weight; if it is less than this, it will be difficult to obtain sufficient scratch resistance and abrasion resistance for the coated film that is formed, and if it is more than this, the viscosity will increase. , it becomes difficult to apply the coating uniformly to the surface to be coated. Suitable solvents for replacing the solvent include those having 1 to 4 carbon atoms;
lower alcohols such as methanol, ethanol, propanol, and butanol; lower carboxylic acids or alkyl esters thereof such as acetic acid and methyl acetate; ethers such as Cellsolve; ketones such as acetone; halogenated hydrocarbons such as methylene chloride; One or more aromatic hydrocarbons such as benzene and toluene. As explained above, the coating composition containing the disilane compound represented by the general formula (1) as a component can form a coating film with excellent properties. The present invention also provides a coating composition that can improve the surface hardness of the resulting coat film by adding a specific compound to the compound. That is, the present invention provides the general formula ...A disilane compound containing a carbonate group represented by (1) (where A is a divalent atomic group containing a carbonate group and having a main chain of at least 7 or more linear atoms, R ¹ and R ² are the same or different alkyl groups or alkoxyalkyl groups, R ³ and
R ⁴ is the same or different alkyl group), and
general formula ^An organoalkoxysilane compound represented ^by So, n
is 0 or 1, R ⁷ is an alkyl group or an alkoxyalkyl group), a tetraalkoxysilane compound represented by the general formula Si(OR ⁸ ) ₄ ...(3) (however, R ⁸ is an alkyl group or an alkoxyalkyl group) This coating composition contains at least one additive selected from colloidal silica, epoxy compounds, and melamine derivatives. Among the above additives, the organoalkoxysilane compound represented by the general formula (2) is generally used, especially those in which R ⁶ has 1 to 4 carbon atoms and R ⁷ has 1 to 4 carbon atoms. Specifically, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, Vinyltrismethoxyethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-
Mercaptopropyltrimethoxysilane, β-
Examples include (3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-aminopropyltriethoxysilane. Further, the tetraalkoxysilane compound represented by the general formula (3) is generally used when R ⁸ has 1 to 4 carbon atoms. Specific examples include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. It is recommended that the alkoxysilane compounds represented by the above general formulas (2) and (3) be used after being hydrolyzed in the same manner as disilane compounds (in this case, it is also possible to hydrolyze without a solvent). be done. For example, the alkoxysilane compound may be hydrolyzed and then added to the disilane compound hydrolyzate solution, or may be hydrolyzed simultaneously with the disilane compound. As colloidal silica, fine silica powder having a particle size of 1 to 100 μm, which is produced by various conventionally known methods, can be used as it is or in the form of a colloidal solution obtained by dispersing it in a polar solvent. For the composition of the present invention, a colloidal solution prepared by dispersing the colloidal silica in a polar solvent, for example, water or an alcoholic solvent such as isopropanol, is preferably adjusted to be slightly acidic. Examples of the epoxy compound include polyolefin epoxy resins, alicyclic epoxy resins, epoxy nopolac resins, and polyglycidyl ethers of polyhydric alcohols, which are manufactured by various conventionally known methods. Melamine derivatives are prepared by conventionally known methods such as mixtures of commercially available alkyl etherified methylolmelamines such as hexamethoxymethylmelamine with nitrified cotton, or precondensates with polyhydric alcohols such as 1,4-butanediol. and can be used. The total amount of the above additives is preferably in the range of 10 to 900 parts by weight, preferably 50 to 200 parts by weight, based on 100 parts by weight of the disilane compound. In order to lower the curing temperature and shorten the curing time, the coating composition of the present invention uses known compounds as curing catalysts, such as hydrochloric acid, sulfuric acid, acetic acid/sodium acetate mixture, tin chloride, perchloric acid, and perchloric acid. Preferably, ammonium, aluminum acetylacetonate, metal naphthenate, p-toluenesulfonic acid, benzoic acid, alkali metal phosphate, sodium thiocyanate, and the like are used. The amount used is preferably 0.01 to 5 percent by weight based on the amount converted into a completely polycondensed state of the polycondensable components in the coating composition (hereinafter referred to as converted amount). Of course, the use of a curing catalyst is not essential. Furthermore, a silicone-based or fluorine-based surfactant may be added to the coating composition of the present invention for the purpose of further improving the smoothness of the coated film. In addition, various other additives such as ultraviolet absorbers, antioxidants, dyes and pigments, and organic carboxylic acids such as formic acid and acetic acid as gelling inhibitors can also be used. In the present invention, the object to be coated is not particularly limited. Generally, molded products with low surface hardness and poor scratch resistance and abrasion resistance, especially plastic molded products, are mainly targeted. For example, polyunsaturated esters such as polymethyl methacrylate, polymethacrylate, polyethylene terephthalate, polyacrylate, and polymethyl acrylate; polystyrene; polyvinyl chloride; epoxy resin; polyamide; polycarbonate; polyallyl such as polydiethylene glycol bisallyl carbonate Carbonates include polymers such as cellulose acetate plastics, and molded products made of copolymers of monomers forming these polymers or copolymers of the monomers and other monomers. In particular, the coating composition of the present invention can be used for plastic molded articles with excellent transparency made of polymers such as polymethacrylic esters, polyacrylic esters, polycarbonates, and polyallyl carbonates. The resulting coating film is highly transparent and has a good appearance, so it is particularly effective in that it does not lose its optical properties. Since the condition of the surface of a plastic molded article greatly affects the properties of the coated film obtained, it is preferable to clean the surface by degreasing and washing with a solvent or the like. In addition, if adhesion is insufficient even with the coating composition of the present invention depending on the plastic fabric, for example, in the case of plastic molded articles made of polycarbonates, styrene polymers, etc., sodium hydroxide aqueous solution, potassium dichromate/sulfuric acid may be used. It is effective to use known methods such as reagent treatment with a solution, discharge treatment with plasma, or primer coating to improve the adhesion between the plastic molded article and the coating film. It is further preferred that the discharge-treated surface dissolves the layer modified by the treatment with a solvent that does not substantially dissolve the plastic. The method of applying the coating composition of the present invention to the surface of a plastic molded article can be used without particular limitation. For example, a method of immersing a molded article in a solution of a coating composition, a method of applying the solution by spraying, brushing, roller, etc. are generally employed. After coating, the coating film is cured by air-drying in dry air or air and usually heat-treated to form a coating film. The heating temperature varies depending on the molded product, but is preferably 50°C or higher, preferably 70°C or higher, or a temperature at which the molded product does not undergo thermal change, generally 150°C or lower. The curing time is approximately 1 hour at a heating temperature of 130°C, and approximately 2 to 4 hours at a heating temperature of 70 to 80°C. The coat film formed by curing can have a thickness of about 0.1 μm to 50 μm, but a thickness of 1 μm to 20 μm is particularly suitable. The coating film thus formed from the coating composition of the present invention has excellent surface properties such as scratch resistance, abrasion resistance, dyeability, hot water resistance, and heat resistance. Examples are shown below to specifically explain the present invention, but the present invention is not limited to these Examples. Note that the performance evaluation of the coat film was carried out by the following method. (1) Adhesion test Place a cutter knife with a sharp tip on the sample surface.
After 100 squares of mm x 1 mm were attached, commercially available cellophane tape was attached and the number of squares remaining when quickly peeled off was measured. (2) Scratch resistance test #0000 in a scratch resistance tester manufactured by Fukuda Machinery Co., Ltd.
The degree of damage to the surface of the test piece was visually observed after attaching steel wool and repeating the test piece surface 10 times under a load of 1 kg. The condition was evaluated on a five-grade scale from A to E with E as the condition. (3) Heat resistance test Leave in an air oven set at 130°C for 3 hours, and visually observe the appearance of the coated film.
If the coat film had no cracks, peeling, blistering, whitening, etc. and had a good appearance, it was rated as ○, and if it was poor, it was rated as ×. (4) Hot water resistance test The coated film was left in boiling water (80°C warm water was used for polymethyl methacrylate) for 2 hours, and the appearance of the coated film was visually observed. If the coat film had no peeling, blistering, cracking, whitening, etc. and had a good appearance, it was rated ○, and if it was poor, it was rated ×. (5) Dyeability test A dyeing bath in which 0.5 parts by weight of a disperse dye (manufactured by Nippon Kayaku Co., Ltd.; Kayalon Polyester, Brown AF) was dispersed and dissolved in 100 parts by weight of water was maintained at 80° C. and dyed for 10 minutes. A is the case where the staining is as good as or better than that of polydiethylene glycol bisallyl carbonate which shows good stainability, and C is the case where it is not stained to the same level or lower than that of polymethyl methacrylate which has poor stainability. It was evaluated in three stages: C. Example 1 A commercially available polymethyl methacrylate plate was used as a plastic molded product. First, it was washed with methanol and thoroughly air-dried to a clear state.
It was immersed in a coating composition having the composition shown in the table, thoroughly air-dried at room temperature, and then cured by heating at 80° C. for 3 hours to obtain a coated film. The coating composition is prepared by mixing and dissolving the compositions shown in Table 1 in equivalent amounts in isopropyl alcohol as a solvent so that the concentration is 30% by weight, and then adding the equivalent amount necessary for hydrolysis of the alkoxy groups in the above composition. After adding 0.05N hydrochloric acid at room temperature and aging for one day, sodium acetate/acetic acid (1/10 weight ratio) was added as a curing catalyst in an amount of 2% by weight based on the converted amount.
The colloidal silica is OSCAL manufactured by Catalysts and Chemicals.
(Product name: SiO ₂ 30% by weight, particle size 10-20m
μ, solvent isopropyl alcohol) was used.
Table 1 also shows the evaluation results of the coating films obtained from each coating solution. In either case, the coating film thickness was about 5 to 10 microns.

【table】

[Table] Example 2 A polyethylene glycol bisallyl carbonate plate produced by cast polymerization was used as a plastic molded article. First, as a pretreatment, the plate was washed with acetone and thoroughly air-dried to a clear state, and then immersed in a 5% NaOH aqueous solution for 5 minutes.
It was thoroughly washed with water and air-dried again. The above-treated plate-like bodies were immersed in coating compositions prepared in exactly the same manner as Nos. 1 to 11 of Example 1 except that no curing catalyst was added, and then thoroughly air-dried at room temperature and heated at 130°C. It was heated and cured for 1 hour to obtain a coated film.
Table 2 shows the evaluation results of the coated films obtained from each coating composition. In either case, the coating film thickness was about 5 to 10 microns.

【table】

[Table] Example 3 Copolymer of 2,2'-bis[4-(2-methacryloxy)-ethoxy-3,5-dibromophenyl]-propane and styrene produced from plastic molded articles by cast polymerization (hereinafter referred to as TB-styrene copolymer) with a TB/styrene weight ratio of 2/3
A plate-like body made of First, as a pretreatment, the plate was washed with acetone and thoroughly air-dried to a clear state, and then treated with an argon/oxygen mixed gas (flow rate: 30ml/min/10ml/
min) under the conditions of a pressure of 0.7 Torr, an output of 200 W, and a processing time of 1 minute, and then washed using an ultrasonic cleaner using acetone as a solvent for 5 minutes, and air-dried again.
The above-treated plate-shaped bodies were coated in the same manner as in Nos. 1 to 11 of Example 2 to obtain coated films. Table 3 shows the evaluation results of the coated films obtained from each coating composition. In either case, the coating film thickness was about 5 to 10 microns.

[Table] Example 4 In No. 5 of Example 1, Instead, a coating composition containing the same amount of polyethylene glycol diglycidyl ether (Epolite 200E, manufactured by Kyoeisha Yushi Co., Ltd.) or a precondensate consisting of 50 parts by weight of hexamethoxymethylmelamine and 50 parts by weight of 1,4-butanediol was added. It is produced by cast polymerization. A plate of polyethylene glycol bisallyl carbonate and TB/styrene copolymer was pretreated and coated in the same manner as in Example 3 to obtain a coated film. In all cases, the coating film had good adhesion (100/100), scratch resistance (A), heat resistance (○), hot water resistance (○), and dyeability (A). Example 5 After washing an aluminum plate with acetone and air drying it to a clear state, it was coated by immersing it in coating solution No. 5 in Table 1, and after being thoroughly air-dried at room temperature,
It was cured by heating at 130°C for 1 hour. The obtained coat film had good adhesion (100/100), scratch resistance (A), heat resistance (○), and hot water resistance (○). Example 6 A coating composition was prepared in the same manner as in Example 1, No. 3, except that the following disilane compound having the atomic group (-A-) shown in Table 4 was used as the disilane compound.

[Formula] Using the coating composition, coating was carried out in the same manner as in Example 1 to form a coat film. The evaluation results of the coated film are also shown in Table 4.

【table】

【table】

Claims (1)

[Claims] 1. General formula A disilane compound containing a carbonate group represented by (where A is 2 containing a carbonate group and having a main chain of at least 7 or more atoms in a straight chain)
functional group, R ¹ and R ² are the same or different alkyl groups or alkoxyalkyl groups, R ³ and R ⁴
are the same or different alkyl groups). 2 General formula A disilane compound containing a carbonate group represented by (where A is 2 containing a carbonate group and having a main chain of at least 7 or more atoms in a straight chain)
functional group, R ¹ and R ² are the same or different alkyl groups or alkoxyalkyl groups, R ³ and R ⁴
are the same or different alkyl groups) and the general formula ^An organoalkoxysilane compound represented ^by So, n
is 0 or 1, R ⁷ is an alkyl group or an alkoxyalkyl group), a tetraalkoxysilane compound represented by the general formula Si(OR ⁸ ) ₄ (however, R ⁸
is an alkyl group or an alkoxyalkyl group), colloidal silica, an epoxy compound, and at least one additive selected from a melamine derivative.