JPH0455615B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a coating composition for eyeglass plastic lenses. (Prior Art and its Problems) In recent years, plastic lenses have rapidly become popular due to their light weight and impact resistance. In particular, diethylene glycol bisallyl carbonate polymer (hereinafter abbreviated as CR-39) is widely used not only as sunglass lenses but also as vision correction lenses. However, plastic lenses have the disadvantage that they are more easily scratched than glass lenses. In order to improve these drawbacks of plastic lenses, the surface of plastic lenses is coated with highly hard silicon compounds such as colloidal silica known as Clark resin and CH ₃ -Si(-
OH) ₃ has been applied and cured by heating (see U.S. Pat. No. 3,986,997), and the coating film obtained by this method has achieved the purpose of improving the surface hardness of plastic lenses. do. Generally, the purpose of applying a silicon compound to the surface of a plastic lens is to use it as an organic hard coat film that increases the surface hardness without impairing the optical performance of the plastic lens, as described above, and to further increase the surface hardness of the plastic lens. It is intended to be used as a base layer for a composite film with an anti-reflection coating applied on top of the film, and in order to increase the hardness of the latter composite film with an anti-reflection coating applied, it is necessary to increase the proportion of colloidal silica. is necessary. Colloidal silica such as Clark resin and CH ₃ −Si(—
In the composition of OH) ₃ , if the proportion of colloidal silica is increased to, for example, 50 mol% or more, cracks may easily occur during heating and curing after the coating composition is applied, and gelation may occur during or after the preparation of a solution of the coating composition. Therefore, it cannot be applied to plastic lenses, or even if it can be applied, it tends to gel on the lens surface and become foreign matter, causing problems such as loss of value as an optical product. Furthermore, the resulting coating film has poor flexibility and poor heat resistance.
These drawbacks are caused by the amount of colloidal silica being 60 mol% or more based on the amount of the two components (on the contrary, CH ₃
This is particularly noticeable when the amount of -Si(-OH) ₃ is less than 40 mol%). In addition, in order to improve the drawbacks of coating compositions consisting of colloidal silica and CH ₃ -Si(-OH) ₃ , such as poor flexibility and the occurrence of cracks during curing, a formula

It has also been done to add an organosilicon compound represented by the formula to the above composition (Japanese Unexamined Patent Publication No. 18626/1983), but the method used in this method

[Formula] has a better flexibility imparting effect than CH ₃ -Si(-OH) ₃ , but it is still not sufficient, and in order to achieve further improvement in flexibility and prevention of cracks, it is necessary to The organosilicon compound

It is necessary to increase the amount of [Formula], which causes a problem that the proportion of colloidal silica, which is a hardening component, decreases relatively, resulting in a decrease in hardness. Conversely, the organosilicon compound

If the amount of [Formula] is decreased and the amount of colloidal silica is increased, problems such as a decrease in flexibility will occur as described above. general formula

When an alkoxysilane having a relatively long R ¹ group is used in the organosilicon compound represented by the formula, for example,
When an epoxy group-containing alkoxysilane and colloidal silica are combined, as shown in Publication No. 111336, the proportion of colloidal silica can be relatively increased, but even in this case, the proportion of colloidal silica is 75 moles. % or more is possible only when difunctional alkoxysilane is used or when colloidal silica is made into water-dispersed colloidal silica with a low concentration of 20% by weight or less of the silica concentration, and in these cases. So, in order to increase the film hardness of a composite film with an antireflection film, which is one of the objectives of the present invention,
I can't say it's enough. In other words, between bifunctional alkoxysilane and trifunctional alkoxysilane, trifunctional alkoxysilane is more advantageous for increasing film hardness, and colloidal silica also has a higher proportion after curing in organosol. However, water dispersion is preferable because there are problems such as cracks in the cured film or gel-like lumps in the cured film. This increases the proportion of water contained in the coating solution, which is not only disadvantageous for increasing film hardness, but also causes problems such as the formation of gel-like lumps, whitening, and a decrease in surface precision. Problems are more likely to occur. Therefore, when using trifunctional alkoxysilane and water-dispersed colloidal silica with as high a concentration as possible (for example, silica concentration of 40% by weight or more), it is necessary to increase the proportion of colloidal silica, but conventional methods With this combination, the coating solution gelled during preparation, making it impossible to form a coating solution. (Means for Solving the Problems) As a result of the inventors' studies to solve the above-mentioned problems of the prior art, we have developed a method using water-dispersed colloidal silica with a high concentration (i.e., silica concentration of 40% by weight or more) as well as general formula (In the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, and R ₂ is an alkylene group having 1 to 4 carbon atoms.) When using a trifunctional organosilicon compound represented by An appropriate amount of organic acid is added, and at least one of the acids is represented by the general formula R ₃ -O-CH ₂ CH ₂ -OH...() (wherein R ₃ is an alkyl group having 1 to 4 carbon atoms). When a cellosolve solvent is used, the above organosilicon compound has a content of 5 to 50% based on the total amount of colloidal silica and organosilicon compound.
A coating composition for eyeglass plastic lenses can be obtained even in a relatively small amount such as 25 mol%, and the coating film obtained from the composition has sufficient flexibility.
It provides heat resistance and weather resistance, and as a result, it is possible to maintain a high proportion of colloidal silica, which is a hardness-imparting component, and serves not only as a hard coat film with wear resistance but also as an anti-reflection film. The present invention was completed by discovering that the surface hardness of the composite film can also be kept high. Therefore, in the present invention, in the presence of highly concentrated water-dispersed colloidal silica, the general formula (In the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, and R ₂ is an alkylene group having 1 to 4 carbon atoms.) A coating composition for eyeglass plastic lenses for forming a cured film obtained by curing, wherein the amount of colloidal silica in the coating composition is 70 to 95 mol% based on the total amount of colloidal silica and organosilicon compound.
(SiO ₂ solid content equivalent value), the amount of the organosilicon compound is 25 to 5 mol%, and the coating composition further contains an organic acid and a solvent as an auxiliary agent in addition to a curing agent, and the coating composition contains an organic acid and a solvent as an auxiliary agent, At least one of them is cellosolve represented by the general formula R ₃ -O-CH ₂ CH ₂ -OH...() (wherein R ₃ is an alkyl group having 1 to 4 carbon atoms), and the high concentration A coating composition for eyeglass plastic lenses, characterized in that the concentration of water-dispersed colloidal silica is 40% by weight or more. As the trifunctional organosilicon compound having the above general formula used in the present invention, R ₁ in the formula
is a methyl group, ethyl group, propyl group or butyl group, and R ₂ is preferably a methylene group, ethylene group, propylene group or butylene group. In addition, the colloidal silica used in the present invention is highly concentrated water-dispersed colloidal silica (i.e., SiO ₂ solid content of 40% or more) in order to leave as little excess water as possible after the hydrolysis of the organosilicon compound. used. Particle size is 5
A material with a diameter of about mμ to 30 mμ is preferable. Specific examples of colloidal silica include Snowtex-40 (Nissan Chemical, SiO ₂ 40% concentration, water-dispersed silica), Cataloid-S1-40 (Catalyst Chemical Industry, SiO ₂ 40% concentration, water-dispersed silica), Cataloid-S1-50 (Catalyst Chemical Industry,
50% concentration, water-dispersed silica), etc. The curing agent used in the present invention includes imidazole derivatives, but acetylacetone metal salts are particularly effective. The amount added is sufficient to harden the colloidal silica and the hydrolyzate of the organosilicon compound, for example, 1 to 10 grams per mole of the total of colloidal silica (SiO ₂ equivalent) and the hydrolyzate of the organosilicon compound. It is. Examples of the organic acid used in the present invention include acetic acid, formic acid, and propionic acid, but acetic acid is preferably used from the viewpoint of stability of the coating liquid. The amount of organic acid added is preferably 5 to 30 grams per mole of the total amount of colloidal silica and organosilicon compound. If the amount is less than this, gelation of the coating liquid will easily occur, and although it can be made more than this, the acetic acid odor will be strong, which is not favorable for work. Among the solvents used in the coating composition of the present invention, cellosolves represented by the general formula (), which are essential solvents, include methyl cellosolve (R ₃ =CH ₃ in the general formula ()), ethyl cellosolve (R ₃ = C ₂ H ₅ ), butyl cellosolve (R ₃ = C ₄ H ₉ ), and the like. Solvents used in combination with Cellosolve include lower alcohols, esters,
Examples include ether and ketone, with isopropyl alcohol and butanol being particularly preferred. The proportion of cellosolve is preferably at least 3% by weight of the total solvent amount, particularly preferably 10% by weight.
That's all. When the proportion of colloidal silica is large as in the present invention, the proportion of cellosolve in the solvent is 3% of the total amount of solvent.
If it is less than % by weight, gelation occurs during preparation of the coating liquid, and the coating liquid cannot be obtained. A silicone surfactant can also be added to the composition of the present invention for the purpose of improving the smoothness of the coating film. Furthermore, it is also possible to add ultraviolet absorbers, antioxidants, etc. for the purpose of improving weather resistance or preventing deterioration of the coating film. Also, the adhesion with the substrate (plastic lens),
Various additives can also be added for the purpose of improving practicality such as improving physical properties. Furthermore, the addition of sodium acetate, which is generally used to stabilize the pH of the coating liquid and also as a catalyst, is not preferred in the present invention. The reason for this is that sodium acetate tends to precipitate toward the film surface after the coating composition is applied and cured, which has a negative effect on the film formation of vapor-deposited substances.Also, the lens surface must be cleaned by hand-wiping or washing before vapor-deposition. This is because even if it is left in place, it will cause the same adverse effects as precipitation due to vacuum or heating. Plastic lenses to which the coating composition of the present invention is applied include CR-39, polymethyl methacrylate (PMMA), polycarbonate,
Examples include plastic lenses such as polystyrene. Next, one example of a method of coating a plastic lens using the composition of the present invention will be explained. First, add an inorganic acid such as hydrochloric acid and an organic acid such as acetic acid to colloidal silica to make it acidic (e.g. pH 2-6), then raise the liquid temperature to 30-30
At 50°C, an organosilicon compound represented by the above general formula () is added dropwise and stirred to hydrolyze the organosilicon compound. A solvent containing cellosolve of general formula () as described above, such as isopropyl alcohol, butanol, and methyl cellosolve are added to the hydrolyzed mixed solution, and a predetermined amount of a curing agent is added. Although the composition thus obtained has a colloidal silica content of 75 to 95 mol%,
Does not easily cause gelation and does not increase viscosity. The composition obtained above is then applied onto a plastic lens by a commonly used dipping method, spin coating method, roll coating method, spraying method, or the like. The composition applied to the plastic lens is cured mainly by heat treatment, and the heating temperature can be varied over a wide range, but is preferably 40°C to 150°C, particularly preferably 80°C.
℃~120℃. A heating time of 1 to 4 hours or more gives good results. The coating film obtained by heat curing treatment has excellent abrasion resistance (hardness), as well as flexibility (flexibility), heat resistance, and chemical resistance. Before applying the coating composition of the invention,
In order to improve the adhesion to the substrate lens, it is preferable to pre-treat the plastic lens by alkali treatment, plasma treatment, ultraviolet irradiation treatment, or the like. The coating film obtained by applying and curing the composition of the present invention on an eyeglass plastic lens is a hard coat layer for a hard coat lens to increase the surface hardness without impairing the optical properties of the eyeglass plastic lens. It is not only used as a coating, but also as a base layer for providing an anti-reflection vapor deposited film on plastic eyeglass lenses.
It is particularly preferable to use it for the latter purpose (base layer for anti-reflection vapor deposited film). (Examples) Examples will be described below in comparison with comparative examples to specifically clarify the effects of the present invention, but the present invention is not limited to these examples. Note that "parts" in the examples are parts by weight. Example 1 240 parts of colloidal silica (Snowtex-40, water-dispersed silica, Nissan Chemical) with a SiO ₂ concentration of 40%,
A mixture of 2.0 parts of 0.5N hydrochloric acid and 20 parts of acetic acid was heated to 35°C, and while stirring, γ-glycidoxypropyltrimethoxysilane (trifunctional organosilicon compound) 95
of the mixture was added dropwise, stirred at room temperature for 8 hours, and left at room temperature for 16 hours. To this hydrolyzed solution, 80 parts of methyl cellosolve, 120 parts of isopropyl alcohol, 40 parts of butyl alcohol, 16 parts of aluminum acetylacetone, 0.2 parts of silicone surfactant, and 0.1 part of ultraviolet absorber were added, and after stirring for 8 hours, the mixture was allowed to cool to room temperature. hand
A coating composition was obtained by aging for 24 hours. The proportion of silicon compounds is colloidal silica.
80 mole% (SiO ₂ solid content equivalent) and 20 mole% of γ-glycidoxypropyltrimethoxysilane. Example 2 A coating composition was obtained in the same manner as in Example 1 except that the amount of γ-glycidoxypropyltrimethoxysilane was changed to 47 parts. The proportion of silicon compounds is colloidal silica.
90 mole% (SiO ₂ solid content equivalent) and 10 mole% of γ-glycidoxypropyltrimethoxysilane. Comparative Example 1 90 parts of colloidal silica (Snowtex-40, Nissan Chemical), 2.0 parts of 0.5N hydrochloric acid, 20 parts of acetic acid, 90 parts of water
After adding 190 parts of methyltrimethoxysilane dropwise with stirring, the mixture was stirred at room temperature for 8 hours and left to stand at room temperature for 16 hours, and a coating composition was obtained in the same manner as in Example 1. The proportion of silicon compounds is colloidal silica.
30 mole% (SiO ₂ solid content equivalent) and 70 mole% of methyltrimethoxysilane. Comparative Example 2 150 parts of colloidal silica (Snowtex-40, Nissan Chemical), 2.0 parts of 0.5N hydrochloric acid, 20 parts of acetic acid, 54 parts of water
After adding 136 parts of methyltrimethoxysilane dropwise with stirring, the mixture was stirred at room temperature for 8 hours and left at room temperature for 16 hours, and the same procedure as in Example 1 was carried out to obtain a coating composition. The proportion of silicon compounds is colloidal silica.
50 mole% (SiO ₂ solid content equivalent) and 50 mole% of methyltrimethoxysilane. Comparative Example 3 To 180 parts of colloidal silica (Snowtex-40, Nissan Chemical) were added 2.0 parts of 0.5N hydrochloric acid, 20 parts of acetic acid, and 36 parts of water, and while stirring, 110 parts of methyltrimethoxysilane was added dropwise, followed by 8 hours at room temperature. After stirring and leaving at room temperature for 16 hours, a coating composition was obtained in the same manner as in Example 1. The proportion of silicon compounds is colloidal silica.
60 mole% (SiO ₂ solid content equivalent) and 40 mole% of methyltrimethoxysilane. Comparative Example 4 480 parts of colloidal silica with a SiO2 concentration of 20% (Snowtex-0, Nissan Chemical), 2.0 parts of 0.5N hydrochloric acid,
After adding 20 parts of acetic acid and stirring, 94 parts of γ-glycidoxypropyltrimethoxysilane was added dropwise, and the same method as in Example 1 was carried out to obtain a coating composition. The proportion of silicon compounds is colloidal silica.
80 mole% (SiO ₂ solid content equivalent) and 20 mole% of γ-glycidoxypropyltrimethoxysilane. Comparative Example 5 2.0 parts of 0.5N hydrochloric acid and 20 parts of acetic acid were added to 240 parts of colloidal silica (Snowtex-40, Nissan Chemical), and 99 parts of γ-glycidoxypropyltrimethoxysilane (bifunctional organosilicon compound) was added while stirring. was added dropwise, and a coating composition was obtained in the same manner as in Example 1. The proportion of silicon compounds is colloidal silica.
80 mole% (SiO ₂ solid content equivalent) and 20 mole% of γ-glycidoxypropyltrimethoxysilane. Comparative Example 6 2.0 parts of 0.5N hydrochloric acid and 20 parts of acetic acid were added to 240 parts of colloidal silica (Snowtex-40, Nissan Chemical), and while stirring, 94 parts of γ-glycidoxypropyltrimethoxysilane was added dropwise, and the mixture was heated to room temperature. After stirring for 8 hours, the mixture was left to stand for 16 hours. Add 120% isopropyl alcohol to this hydrolysis solution.
120 parts of butyl alcohol and 16 parts of aluminum acetylacetone were added, but gelation occurred at this stage and a white precipitate formed, making it impossible to obtain a coating solution. Test example: The test was conducted on CR that was cleaned after alkali treatment.
-39 A hard coat lens in which a coating composition was applied to a lens by dipping at a pulling speed of 15 cm/min, left at room temperature for 15 minutes, and then heated and cured at 120°C for 2 hours to form a coating film, and the hard coat. An antireflection film was applied by vacuum deposition on the cured coating film of the lens.
Anti-reflection coatings are generally made of materials with a high refractive index, such as
This is done by layering materials such as TiO ₂ and ZrO ₂ with a substance with a low refractive index, but here
A layered structure of ZrO ₂ and SiO ₂ was adopted. The outline of various test methods will be explained below. (a) Abrasion resistance Additional load applied to the surface using #0000 steel wool
After rubbing 500 times (back and forth) with 1000 g, the following judgment was made. A: Almost no damage. B: Slight damage. C: Many scratches occur. D: Peeling of the film occurs. This test was conducted on both a plastic lens with a hard coat film and a plastic lens with an antireflection film of the hard coat film. (b) Adhesion 10×10 1 mm square goblets were made, and a peel test using cellophane adhesive tape was performed three times to determine the number of remaining gobs. The cellophane tape used is Nichiban JIS-Z-1522.
It was from. (c) Appearance Transparency, coloration, surface condition, etc. were examined with the naked eye. (d) Heat resistance and hot water resistance ○ A plastic lens coated with the coating composition of the present invention and cured is placed in a constant temperature oven at 150°C.
It was investigated whether cracks were present in the coating film. B○ It was immersed in boiling water for 1 hour and examined for any changes in appearance. (e) Weather resistance Xenon Long Life Weather Meter WEL
Accelerated exposure was performed for 500 hours using -25AX (Suga Test Equipment) to check whether the coating film had yellowed or deteriorated. (f) Chemical resistance The coating film was immersed in the following solution for 1 hour at room temperature to examine changes in the coating film. 1 10% NaOH solution 2 10% HCl solution 3 Acetone solution 4 Methanol solution The test results for the coating compositions of Examples 1-2 and Comparative Examples 1-5 are shown in the table below.

【table】

[Table] As is clear from the above table, the coating compositions of Examples 1 and 2 produced coating films that were excellent in appearance, adhesion, heat resistance, hot water resistance, weather resistance, chemical resistance, and abrasion resistance. In contrast, the coating compositions of Comparative Examples 1 to 5 were inferior in at least one of the above properties. Furthermore, in Examples 1 and 2, the improvement in abrasion resistance was particularly remarkable in the plastic lenses having a hard coat film (base layer) and an antireflection vapor deposited film. Even in the component systems of colloidal silica and methyltrimethoxysilane shown in Comparative Examples 1 to 3, as the proportion (mole%) of colloidal silica increases, the hardness of the composite film as an underlayer of an antireflection film increases.
As can be seen, cracks begin to occur when the proportion of colloidal silica exceeds 60 mole%. Therefore, the proportion of colloidal silica cannot be increased beyond this point, and the hardness of the composite film cannot be improved beyond a certain level. (Effects of the Invention) Although the coating composition for plastic cleansing of the present invention uses a high concentration of colloidal silica and a trifunctional organosilicon compound, the organosilicon compound has a long chain organic group containing an epoxy group. Even if the organosilicon compound is contained in an extremely small amount, the coating film is provided with sufficient properties such as flexibility, heat resistance, and chemical resistance, and the addition of organic acids and solvent system As a result, by careful selection, the amount of colloidal silica can be kept high, and the surface hardness (abrasion resistance) of the coating film can also be kept high.

Claims (1)

[Claims] 1. In the presence of highly concentrated water-dispersed colloidal silica, the general formula (In the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, and R ₂ is an alkylene group having 1 to 4 carbon atoms.) A coating composition for eyeglass plastic lenses for forming a cured film obtained by curing, wherein the amount of colloidal silica in the coating composition is 70 to 95 mol% based on the total amount of colloidal silica and organosilicon compound.
(SiO ₂ solid content equivalent value), the amount of the organosilicon compound is 25 to 5 mol%, and the coating composition further contains an organic acid and a solvent as an auxiliary agent in addition to a curing agent, and the coating composition contains an organic acid and a solvent as an auxiliary agent. At least one of them is cellosolve represented by the general formula R ₃ -O-CH ₂ CH ₂ -OH...() (wherein R ₃ is an alkyl group having 1 to 4 carbon atoms), and the high concentration A coating composition for eyeglass plastic lenses, characterized in that the concentration of water-dispersed colloidal silica is 40% by weight or more. 2. The coating composition for eyeglass plastic lenses according to claim 1, wherein the organic acid is acetic acid, and the amount added is 5 to 30 g per 1 mole of the total amount of colloidal silica and organosilicon compound.