JP2006193537A - Coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition forming an excellent protective film having excellent adhesiveness, scuff resistance, hot water resistance, flexibility, etc., by coating the surface of a plastic molded product with the composition and curing the composition. <P>SOLUTION: The coating composition is composed of a hydrolysis and condensation product of a mixture of (A) 65-90 wt.% of at least one kind of organoalkoxysilane represented by general formula R<SP>1</SP>Si(OR<SP>2</SP>)<SB>3</SB>with (B) 1-10 wt.% of at least one kind of tetraalkoxysilane represented by general formula Si(OR<SP>3</SP>)<SB>4</SB>, (C) 1-10 wt.% of a γ-glycidoxypropylmethyldialkoxysilane and (D) 3-20 wt.% of at least one kind of organoalkoxydisilane represented by general formula (R<SP>5</SP>O)<SB>3-X</SB>R<SP>7</SP><SB>X</SB>Si-R<SP>4</SP>-SiR<SP>8</SP><SB>Y</SB>(OR<SP>6</SP>)<SB>3-Y</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coating composition capable of forming a protective film excellent in scratch resistance, contamination resistance and chemical resistance on the surface of a molded article by applying and curing it on the surface of a plastic molded article or the like. It is about.

  Since plastics have the advantages of being lighter than glass and having good workability, their uses are expanding in recent years. However, the surface of the plastic is very easily scratched, and the appearance is impaired by repeated rubbing. Therefore, the scratch resistance is improved by providing a hard coat layer on the surface.

As a method for improving the scratch resistance of the surface of a plastic molded product, in particular, a polyacrylic resin or polycarbonate resin molded product, a cured film is formed by applying a hydrolyzate of a siloxane compound to the surface of the molded product. Have been put to practical use in sunglasses lenses, prescription lenses, optical lenses, automobile meter covers, and the like (Patent Documents 1 and 2).
JP 56-22365 A JP 61-166824 A

  In addition, when passing through an assembly process, flexibility and abrasion resistance are required, and as a hydrolyzate of a siloxane compound, a bifunctional silane compound, a trifunctional silane compound, and a tetrafunctional silane compound are used. In general, the amount ratio of each component is adjusted, or a hard polymer compound is added.

  In recent years, however, plastic molded products, especially displays, have become more deformed during assembly and use as their size increases, and quality that is more flexible than before has been required. It has been difficult to meet these requirements with a cured film formed of a bifunctional silane compound, a trifunctional silane compound, and a tetrafunctional silane compound.

  That is, since these known coating compositions described above are poor in flexibility, when coated on a soft resin such as a polycarbonate resin, there is a defect that the film tends to crack during processing or use. In order to solve the problem, a polymer compound or the like to which a different kind of compound is added is inferior in hardness as compared to a cured film formed only with a silane compound, so that flexibility is improved, but scratch resistance becomes insufficient, Further, when stored for a long time, there are problems such as poor liquid stability.

  In view of the above, the present inventors have particularly good adhesion to a molded product made of polycarbonate resin, excellent flexibility, and high hardness and wear resistance on the surface of the molded product, As a result of intensive studies to obtain a coating composition capable of easily forming a protective film having chemical resistance and transparency, it was found that difunctional silane compounds, trifunctional silane compounds, and tetrafunctional silane compounds. In addition, if a 4- to 6-functional polyfunctional silane compound formed via a non-reactive hydrocarbon group is used in combination, a film having excellent flexibility can be obtained without impairing scratch resistance. In addition, the present inventors have found that a coating composition having excellent long-term liquid stability can be obtained, and have led to the present invention.

The invention according to claim 1, (A) the general formula _{^{R 1 Si (OR 2) 3}} ( where, ^{R 1} is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, ^{R 2} is 1 to the number of carbon atoms And at least one organoalkoxysilane represented by the formula (B) having a general formula Si (OR ³ ) ₄ (wherein R ³ has 1 to 4 carbon atoms) 1 to 10% by weight of at least one tetraalkoxysilane represented by (saturated hydrocarbon group), 1 to 10% by weight of (C) γ-glycidoxypropylmethyl dialkoxysilane, and (D) the general formula ^{_{(R 5 O) 3-X}} R 7 X Si-R 4 -SiR 8 Y (OR 6) 3-Y ( where, ^{R 4} is a saturated hydrocarbon group having 1 to 12 carbon ^atoms, R 5, ^{R 6} carbon C1-4 saturated hydrocarbon ^group, R 7, ^{R 8} is saturated or having 1 to 4 carbon atoms A hydrocarbon group having a saturated, _{X, Y} is a coating consisting of 0 or at least one and organo alkoxy disilanes 3 to 20 wt% is represented by 1 and is), the hydrolysis-condensation product of a mixture of It is characterized by a composition.

The invention according to claim 2, (A) the general formula _{^{R 1 Si (OR 2) 3}} ( where, ^{R 1} is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, ^{R 2} is 1 to the number of carbon atoms And at least one organoalkoxysilane represented by the formula (B) having a general formula Si (OR ³ ) ₄ (wherein R ³ has 1 to 4 carbon atoms) 1 to 10% by weight of at least one tetraalkoxysilane represented by (saturated hydrocarbon group), 1 to 10% by weight of (C) γ-glycidoxypropylmethyl dialkoxysilane, and (D) the general formula ^{_{(R 5 O) 3-X}} R 7 X Si-R 4 -SiR 8 Y (OR 6) 3-Y ( where, ^{R 4} is a saturated hydrocarbon group having 1 to 12 carbon ^atoms, R 5, ^{R 6} carbon C1-4 saturated hydrocarbon ^group, a saturated or unsaturated in R 7, ^{R 8} carbons 1-4 A hydrocarbon group of the sum, _{X, Y} for 0 or 1 at a) at least one and organo alkoxy disilanes 3 to 20 wt% is represented by a mixture of hydrolysis-condensation products of, (E) A coating composition comprising 2 to 25% by weight of colloidal silica dispersed in an aliphatic alcohol having 1 to 8 carbon atoms in terms of solid content is characterized.

  According to the first aspect of the present invention, a curing catalyst and a solvent are added to the hydrolysis / condensation product of the mixture composed of the silane compounds specified by (A), (B), (C), and (D). By forming a coating composition, the coating film made of the composition is excellent in scratch resistance, stain resistance, chemical resistance, flexibility, solvent resistance, etc., and particularly molded from a polycarbonate resin. It is useful for protecting the surface of products or molded plates.

  According to the invention described in claim 2, a curing catalyst and a solvent are added to the hydrolysis / condensation product of the mixture comprising the silane compound specified by (A), (B), (C), (D). A composition obtained by further adding 2 to 25 wt% of colloidal silica (E) dispersed in an aliphatic alcohol having 1 to 8 carbon atoms to the composition described in claim 1 As a result, in addition to the performance of the film made of the composition of claim 1, a film having further improved flexibility and performance such as durability can be obtained.

For these reasons, the coating composition of the present invention is used in a wide range of applications including large-sized members such as sunglasses, eyesight correction glasses, protective glasses, leisure underwater glasses, automobile parts, electrical parts, building materials. be able to. In addition, it can also be applied to the surface of various plastics such as nylon and polyethylene terephthalate, wood, metal, ceramic, paper, and non-woven fabric.

Hereinafter, the present invention will be described in detail. In the present invention, specific examples of the saturated hydrocarbon group having 1 to 4 carbon atoms represented by R ¹ and R ² in the component (A) represented by the general formula R ¹ Si (OR ² ) ₃ include An alkyl group such as methyl, ethyl, propyl and butyl is included, and the unsaturated hydrocarbon group having 1 to 4 carbon atoms represented by R ¹ includes an alkenyl group such as vinyl and allyl.

The component (A) represented by the general formula R ¹ Si (OR ² ) ₃ includes methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n- Propyltrimethoxysilane, n-propyltriethoxysilane and the like are used.

Examples of the component (B) represented by the general formula Si (OR ³ ) ₄ include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

  Examples of the (C) component γ-glycidoxypropylmethyl dialkoxysilane include γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and the like.

Formula _{^{(R 5 O) 3-X}} R 7 X Si-R 4 -SiR 8 Y (OR 6) 3-Y represented by (D) saturated having 1 to 12 carbon atoms represented by ^{R 4} in component Specific examples of the hydrocarbon group include alkylene groups such as ethylene, propylene, butylene, hexamethylene, octamethylene, and dodecamethylene, or polymethylene groups, and carbons represented by R ⁵ , R ⁶ , R ^7, and R ^8. Examples of the saturated hydrocarbon group having 1 to 4 include alkyl groups such as methyl, ethyl, propyl, and butyl. Further, the unsaturated hydrocarbon group having 1 to 4 carbon atoms represented by R ⁷ and R ⁸ includes alkenyl groups such as vinyl and allyl.

  As the component (D) represented by the above general formula, 1,4-bis (trimethoxysilyl) butane, 1,4-bis (methyldimethoxysilyl) butane, 1,4-bis (triethoxysilyl) butane 1,6-bis (trimethoxysilyl) hexane, 1,6-bis (methyldimethoxysilyl) hexane, 1,6-bis (triethoxysilyl) hexane, 1,12-bis (trimethoxysilyl) dodecane, , 12-bis (triethoxysilyl) dodecane and the like.

  In this invention, the component (A) in the above general formula is 65 to 90% by weight, the component (B) is 1 to 10% by weight, the component (C) is 1 to 10% by weight, and the component (D) is 3 to 3% by weight. Mixing at a specific ratio of 20% by weight to perform hydrolysis / condensation, but within the range not impairing its properties, γ-methacryloxypropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane other than those described above A trifunctional silane compound such as dimethyldimethoxysilane or dimethyldiethoxysilane can also be used in combination.

  The mixing ratio of each of the above components used for obtaining the coating composition of the present invention will be described. The component (B) is 1 to 10% by weight (preferably 2 to 8% by weight) from 1% by weight. If it is less, hardness, scratch resistance, etc. will be insufficient when the obtained composition is coated on a polycarbonate resin molded product, and if it is used more than 10% by weight, flexibility will be reduced, This is because cracks are likely to occur when the substrate is deformed during use.

  The component (C) is 1 to 10% by weight (preferably 2 to 8% by weight). When the amount is less than 1% by weight, when the obtained composition is coated on a polycarbonate resin molded article, the adhesion and This is because flexibility is lowered, and when it is used more than 10% by weight, hardness, scratch resistance and the like are lowered.

  When the component (D) is 3 to 20% by weight (preferably 4 to 15% by weight) is less than 3% by weight, when the obtained composition is coated on a polycarbonate resin molded product, the hardness, This is because the scratch resistance and the like are insufficient, and if it is used in an amount of more than 20% by weight, the flexibility is lowered, and cracks are likely to occur when the substrate is deformed during processing and use.

  In the present invention, a composition obtained by adding a curing catalyst and a solvent to a hydrolysis / condensation product of a mixture composed of the silane compounds specified in (A), (B), (C), and (D) above. Furthermore, as a component (E), colloidal silica dispersed in an aliphatic alcohol having 1 to 8 carbon atoms is added to form a composition, whereby the coating film made of the composition is further flexible in the above performance. , Durability and the like can be imparted. The colloidal silica (E) dispersed in the aliphatic alcohol having 1 to 8 carbon atoms is obtained by hydrolysis / mixing of a mixture composed of the silane compounds specified in (A), (B), (C), and (D). It is preferable to use 2 to 25% by weight based on the solid content of the condensation product. This is because if the amount is less than 2% by weight, the effect of imparting flexibility and durability is small, and if the amount is more than 25% by weight, the hardness may be lowered.

  In this invention, in order to improve performance, such as the dyeability of the coating film by the obtained composition, an organic polymer compound can be mix | blended as needed. Examples of such organic polymer compounds include epoxy resins, acrylic resins, polyvinyl butyral resins, polyurethane resins, and melamine resins, among which acrylic resins, polyvinyl butyral resins, and melamine resins are preferable, and the amount thereof is scratch resistance, etc. From the above point, 0.1 to 5% by weight in terms of solid content is appropriate for the hydrolysis / condensation product of the mixture comprising the silane compound specified in (A), (B), (C) and (D) above. It is.

Next, in the coating composition of the present invention, a curing catalyst can be used for the purpose of increasing the curing rate and further improving the adhesion to the molded product. Particularly effective for dehydration condensation of silanol groups, such as boron trifluoride and its complexes with electron donors, various Lewis acids such as ZnCl ₂ and AlCl ₃ and their complexes, sodium acetate, cobalt naphthenate, etc. Organic acid metal salts, metal borofluorides, organic esters of boric acid, organic titanates, metal acetylacetonates such as chromium acetylacetonate, aluminum acetylacetonate, n-butylamine, tri-n-butylamine, etc. Amines, 1,8-diazabicyclo (5,4,0) undecene-7,1,5-diazabi Bicyclic amidine such as cyclo (4,3,0) nonene-5 or a salt thereof, and the like. Among them, bicyclic amidine or a salt thereof is particularly preferable, and usually the above (A) and (B) , (C), (D) may be used in an amount of 0.01 to 5% by weight based on the solid content of the mixture comprising the specified silane compound.

  The coating composition of the present invention is applied to the surface of a plastic molded article in the form of an organic solvent solution. As the solvent, water, alcohols, ketones, esters, cellosolves, acetic acid, dioxane, toluene, xylene, etc., which are conventionally used in this kind of composition, are used alone or as a mixed solvent of two or more kinds. That's fine. Of these, solvents mainly composed of alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol and butyl alcohol, esters such as ethyl acetate and butyl acetate, and mixtures thereof are preferred.

  In the coating composition of the present invention or the solvent solution thereof, various known additives such as an anti-gelling agent, a coating film smoothness improver, an ultraviolet absorber, an antioxidant, a colorant, and the like as necessary. Can be optionally added.

  Typical anti-gelling agents include organic carboxylic acids such as formic acid and acetic acid, and coating film smoothness improvers include silicone surfactants such as copolymers of lower alkylene oxide and lower dialkyl siloxane, coloring Examples of the agent include various dyes and pigments. Various organic polymer fine powders, inorganic fillers and the like can also be added for the purpose of thickening, improving adhesion, adjusting gloss, improving hardness and improving durability.

  As a method for applying the coating composition of the present invention to a plastic molded article, it may be carried out by various methods such as dipping, spraying, roll coating, etc., according to conventional methods, and curing of the coated film after application is also possible. According to a conventional method, it can be carried out easily by heating at a temperature at which the substrate does not undergo thermal deformation, usually at a temperature of about 70 to 130 ° C.

  The coating amount when applying the coating composition of the present invention to the surface of a plastic molded product, that is, the coating thickness, can be appropriately selected according to the purpose of use of the material to be coated, such as automobiles, electrical parts, optical equipment, building materials. For normal use purposes such as about 1 to 10 μm, it is possible to form a protective film exhibiting desired performance such as wear resistance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these Examples. All the parts are parts by weight.

Example 1
125 parts of 0.02N hydrochloric acid, 245 parts of isopropyl alcohol, and 30 parts of butyl cellosolve were mixed, and 300 parts of methyltriethoxysilane, 10 parts of tetraethoxysilane, 35 parts of γ-glycidoxypropylmethyldimethoxysilane and 1,6- A mixture of 75 parts of bis (trimethoxysilyl) hexane was gradually added dropwise with stirring at a temperature of 20 to 25 ° C., and further stirred at 50 ° C. for 3 hours. In the mixture thus obtained, 0.3 part of a silicone surfactant (BYK-306, manufactured by BYK Japan), 20 parts of acetic acid and 1,8-diazabicyclo (5,4,0) undecene-7 were added to 0.8 parts. Parts at room temperature to obtain a coating composition having a solid content of 23% and a viscosity of 8 mPa · s / 20 ° C.

Subsequently, the coating composition obtained above was applied to a polycarbonate extruded sheet of 190 mm × 60 mm and a thickness of 2 mm (manufactured by Plastic Co., Ltd., Polyacece) in a room at 20 ° C. and 65% RH at a pulling rate of 20 cm / min. The film was applied by a dipping method, and then heated and cured with a hot air dryer at 120 ° C. for 120 minutes to form a 2 μm coating film on the molded sheet.

  The thus-obtained sheet on which a coating film made of the coating composition of the present invention was formed was subjected to performance tests such as appearance, adhesion, and scratch resistance. The results are shown in Table 1.

The test method for the performance test is as follows.
Appearance: The transparency of the coating film was visually evaluated.
-Adhesiveness: Adhesive tape (Nichiban Co., Cellotape (registered trademark)) is firmly attached to the coating surface, peeled rapidly in the direction of 90 degrees, and examined for the presence or absence of coating film,
○: No abnormality, ×: Abnormal.
(3) Scratch resistance: The surface of the coating is rubbed with steel wool (manufactured by Nippon Steel Wool Co., Ltd., # 0000). Then, the determination was made in three stages: a slight scratch, C: scratch even with a weak friction.
-Flexibility: After the sample was pressed strongly against a steel cylindrical surface with a diameter of 40 mm and 60 mm with the coating surface facing outward, the presence or absence of cracks in the coating was examined,
A: No crack generation at 40 mm, B: No crack generation at 60 mm,
X: A three-stage evaluation was performed in which cracks were observed at 60 mm.
-Hot water resistance: The coating film was immersed in hot water at 80 ° C. for 60 minutes and then taken out to examine the appearance and adhesion.
・ Liquid stability: Evaluate the presence or absence of gelation and liquid separation after storage for 3 months at 30 ℃,
○: No change, Δ: Slightly supernatant or precipitate was observed, ×: Gelation was performed, and a clear supernatant or precipitate was clearly observed.

Examples 2-4
Coating compositions were prepared in the same manner as in Example 1 with the formulations of Examples 2 to 4 shown in Table 1. And after apply | coating to a polycarbonate shaping | molding plate like Example 1, and heat-curing and forming a coating film, said performance test was done like Example 1. FIG. The results are shown in Table 1.

Example 5
(E) The composition shown in Table 1 and the same method as in Example 1 except that isopropanol-dispersed colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name IPA-ST) having a solid content concentration of 30% was added as a component. A coating composition was prepared. And after apply | coating to a polycarbonate shaping | molding plate like Example 1, and heat-curing and forming a coating film, said performance test was done like Example 1. FIG. The results are shown in Table 1.
Comparative Examples 1-3

Coating compositions were prepared in the same manner as in Example 1 with the formulations of Comparative Examples 1 to 3 shown in Table 1. And after apply | coating to a polycarbonate shaping | molding plate like Example 1, and heat-curing and forming a coating film, said performance test was done like Example 1. FIG. The results are shown in Table 1.
Comparative Example 4

  As component (E), an isopropanol-dispersed colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name IPA-ST) having a solid content concentration of 30% is added, and a polyacrylic acid ester copolymer resin (manufactured by Seiko Kasei Co., Ltd.) is added to the resulting mixture. A coating composition was prepared in the same manner as in Example 1 except that Lackskin A-40, solid content 30%) was added. And after apply | coating to a polycarbonate shaping | molding plate like Example 1, and heat-curing and forming a coating film, said performance test was done like Example 1. FIG. The results are shown in Table 1.

  From the above test results, as shown in Table 1, the coating film of the comparative example lacking any of the components (A) to (E) essential for the coating composition of the present invention or these components It was confirmed that the coating film using the coating composition of the present invention was superior in all performances as compared with the coating film of the comparative example in which was used in an amount ratio outside the range specified in the present invention.

Claims (2)

(A) General formula R ¹ Si (OR ² ) ₃ (where R ¹ is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, and R ² is a saturated hydrocarbon group having 1 to 4 carbon atoms) 65 to 90% by weight of at least one organoalkoxysilane represented by:
(B) 1 to 10% by weight of at least one tetraalkoxysilane represented by the general formula Si (OR ³ ) ₄ (wherein R ³ is a saturated hydrocarbon group having 1 to 4 carbon atoms);
(C) 1 to 10% by weight of γ-glycidoxypropylmethyl dialkoxysilane,
(D) formula _{^{(R 5 O) 3-X}} R 7 X Si-R 4 -SiR 8 Y (OR 6) 3-Y ( where, ^{R 4} is a saturated hydrocarbon group having 1 to 12 carbon atoms, ^{R 5} , R ⁶ is a saturated hydrocarbon group having 1 to 4 carbon atoms, R ⁷ and R ⁸ are saturated or unsaturated hydrocarbon groups having 1 to 4 carbon atoms, and _{X and Y} are 0 or 1. A coating composition comprising 3 to 20% by weight of a mixture of at least one organoalkoxydisilane and a hydrolysis / condensation product of the mixture. (A) General formula R ¹ Si (OR ² ) ₃ (where R ¹ is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, and R ² is a saturated hydrocarbon group having 1 to 4 carbon atoms) 65 to 90% by weight of at least one organoalkoxysilane represented by:
(B) 1 to 10% by weight of at least one tetraalkoxysilane represented by the general formula Si (OR ³ ) ₄ (wherein R ³ is a saturated hydrocarbon group having 1 to 4 carbon atoms);
(C) 1 to 10% by weight of γ-glycidoxypropylmethyl dialkoxysilane,
(D) formula _{^{(R 5 O) 3-X}} R 7 X Si-R 4 -SiR 8 Y (OR 6) 3-Y ( where, ^{R 4} is a saturated hydrocarbon group having 1 to 12 carbon atoms, ^{R 5} , R ⁶ is a saturated hydrocarbon group having 1 to 4 carbon atoms, R ⁷ and R ⁸ are saturated or unsaturated hydrocarbon groups having 1 to 4 carbon atoms, and _{X and Y} are 0 or 1. 3-20% by weight of at least one organoalkoxydisilane,
For the hydrolysis / condensation product of the mixture consisting of
(E) A coating composition comprising 2 to 25% by weight of colloidal silica dispersed in an aliphatic alcohol having 1 to 8 carbon atoms, based on the solid content.