JPH0735485B2 - UV resistant, abrasion resistant coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention This invention relates generally to protective coatings on plastics such as polycarbonate, and more particularly to coatings that protect the underlying substrate from damage caused by exposure to ultraviolet light.

(2) Background of the invention U.S. Pat. No. 4,275,118 to Baney et al. Discloses colloidal titanium oxide, colloidal silica and colloidal silica in alcohol-water media which, when cured on a plastic surface such as polycarbonate, produces a hard and abrasion resistant coating. Disclosed are coating compositions comprising an acidic dispersion of hydroxylated silsesquioxane.

U.S. Pat. No. 4,299,746 to Frye hydrolyzes an alkyltrialkoxysilane in an aqueous colloidal silica dispersion and adds to the hydrolysis product a small amount of a UV absorbing compound such as 2,4-dihydroxybenzophenone. Disclosed are improved silicone resin abrasion resistant coating compositions prepared.

U.S. Pat. Nos. 4,390,373 and 4,442,168 to White et al. Are water-alcohol solutions of less than about 30:70 by weight ratio of partial condensates of R (Si (OH) ₃ ), where R is an organic radical. A cured, transparent, abrasion resistant coating composition is disclosed that includes an effective amount of an abrasion resistant colloidal dispersion containing colloidal antimony oxide and colloidal silica therein.

US Pat. No. 4,395,461 to Ching first treats the surface of a polycarbonate substrate with a solution of a hydrolyzed silylated organic UV screen, and then applies a curable silicone hardcoat composition on the treated surface. A method for improving the weather resistance of a polycarbonate substrate is disclosed.

U.S. Pat.No. 4,405,679 to Fujioka et al. Discloses improved abrasion resistance, including a molded polycarbonate substrate, a cured undercoat applied to the substrate, and a cured overcoat applied to the undercoat. Discloses coated molded articles of the polycarbonate type resin. The overcoat is an epoxy-containing silicon compound that is at least one member of a group of hydrolyzates of organosilicon compounds, colloidal silica and organotitanic acid,
And a curing catalyst.

U.S. Pat. No. 4,477,499 to Doin et al. Discloses a UV resistant silicone resin coating with improved thermoformability and reduced required aging achieved by adding a Lewis acid compound to the coating composition. .

US Pat. No. 4,500,6 to Ashlock et al.
69 and No. 4,571,365 are transparent containing colloidal dispersions of water-insoluble dispersoids containing metals, alloys, salts, their oxides and hydroxides, in a water-alcohol solution of a partial condensate of silanols. , Abrasion Resistant Coating Compositions.

U.S. Pat. No. 4,552,936 to Moore is a protective coating containing polycaprolactone polyol and aminoplast derivative applied to a thermoplastic substrate to make a thermoformable article that is abrasion resistant, solvent resistant and weather resistant. A composition is disclosed.

U.S. Pat. No. 4,615,947 to Goosens,
A primer layer comprising a thermoplastic or thermoset acrylic intimate mixture with an organopolysiloxane that enhances abrasion adhesion and a solvent resistant organopolysiloxane hardcoat to a thermoplastic substrate are described.

U.S. Pat. No. 4,683,169 to Curry et al. Discloses a methylmethacrylate UV protective coating for polycarbonate films with improved resistance to microcracking.

"Zol-" by Dow Corning's Baney et al.
European Patent Application No. 851102939 published 86.02.05 entitled "Carbon Containing Monolith Glass Prepared By Gel Process"
Discloses an intermediate containing a dispersion of a colloidal metal oxide in a water-alcohol solution of a partial condensate of silanol having the formula RSi (OH) ₃ . Here, the metal oxides are ZrO ₂ and SnO.
₂ , ZrSiO ₄ , B ₂ O ₃ or La ₂ O ₃ .

Optical quality abrasion resistant coated plastic materials typically require a coating that protects the substrate from ultraviolet (UV) damage. Hydrolytic degradation is clearly accelerated by exposure to UV,
UV protection is particularly important for polycarbonate. Most typical organic UV absorbers cannot be added in sufficient amount to water / alcohol based sol-gel type abrasion resistant coating compositions due to their low solubility, and also the hardness and coating adhesion. Conventional UV stabilizers do not provide sufficient protection to abrasion resistant coatings as they cannot be added without adversely affecting the force. Furthermore, typical UV absorbers usually gradually lose activity after prolonged exposure and may also gradually leach out of the composition.

(3) SUMMARY OF THE INVENTION The present invention provides protection from UV damage to underlying plastic substrates such as polycarbonate, the method comprising a transparent coating containing a UV absorbing organic compound containing a hydrophilic moiety having terminal hydroxyl groups. The compound is capable of reacting with silanol groups in a sol in which silicon and / or other metal alkoxides have been partially hydrolyzed, and they are hydrolytically and polycondensed to provide abrasion resistance to the plastic substrate surface. Form a film to give. The hydrophilically improved hydroxybenzotriazole and hydroxybenzophenone derivatives of this invention are compatible with alcoholic / aqueous sol-gel compositions and processes and are UV protected without compromising the abrasion resistance of the inorganic oxide coating. I will provide a. The present invention also provides protection from UV damage to the underlying plastic substrate such as polycarbonate, the method including the addition of hydroxybenzophenone and hydroxybenzotriazole in a polymeric mixture of (meth) acrylic copolymers. A coating of a composition comprising a UV absorbing organic compound which is a colorless, highly efficient UV absorber and a positive solvent which enhances the adhesion of the coating to the substrate.

(4) Description of the Preferred Embodiments A coating that protects plastic substrates such as polycarbonate from damage caused by UV radiation is formed from a sol containing a network-forming metal alkoxide such as alkoxysilane and other metal alkoxides. The alkoxysilane is an organoalkoxysilane, such as an alkylalkoxysilane or other organofunctional alkoxysilane. The alkoxide may be in the form of a dimer or higher condensed, as far as the rest of the hydrolyzable alkoxide groups are concerned, including the alkyl or aryl groups. A UV absorbing organic compound containing a hydroxy group capable of reacting with a silanol group is added to the partially hydrolyzed sol. Hydrolysis and condensation occur in situ.
Alternatively, the alkoxide is partially or fully hydrolyzed and partially condensed before being combined with an organic UV absorber containing hydroxyl groups, preferably hydroxybenzotriazole.

Conventional UV absorbers such as benzophenone and benzotriazole and their alkyl derivatives have low solubility in alcohol-water based inorganic sol-gel type abrasion resistant coatings. And also, because of the lack of covalent bonds between conventional UV absorbers and the inorganic coating matrix, organic UV absorbers leach out during short term use.

According to this invention, hydroxybenzotriazole and hydroxybenzophenone UV absorbers are modified by the extension of hydrophilic chains with terminal hydroxy groups for condensation reaction with the inorganic sol, and upon curing become part of the polymer oxide network. Become. The presence of ethoxy and / or propoxy hydrophilic moieties provides a liquid organic UV absorber and at the same time improves the miscibility with the inorganic sol. Polyethylene glycol substituted hydroxybenzotriazoles of the following formula are preferred UV absorbers according to the invention.

Here, n is 1 to 10. A suitable composition is available as Tinuvin 1130 from Ciba Geigy.

The resulting composition can be used as a coating composition both as a primer or as a protective coating on a substrate or coated substrate. In an alternative embodiment, the composition can be added to other coating compositions such as abrasion resistant coating compositions to increase resistance to UV radiation. In either case, the coating composition can be applied by any of the conventional techniques such as spraying, dipping, or flow coating. The composition dries and cures to form a uniform, durable coating that adheres well to plastic substrates such as polycarbonate. The coating protects the substrate from UV radiation by providing strong and broad absorption in the 240 to 380 nanometer range.

In a preferred embodiment of this invention, the alkoxide is partially hydrolyzed prior to the addition of the UV absorbing organic compound containing hydrophilic extended chains with less than hydroxyl groups capable of reacting with silanol groups. Preferably, the alkoxide is an alkoxysilane of the general formula RxSi (OR ') _4- x, where R is selected from the group consisting of organic radicals and R'is a low molecular weight alkyl radical, and x is less than 4 and may be zero. The organic radical of R is preferably alkyl, vinyl, methoxyethyl, phenyl, γ-glycidoxypropyl, or γ-methacryloxypropyl. The alkoxide is hydrolyzed by the following general reaction.

_{RxSi (OR ') 4- x +} yH 2 O → RxSi (OR') 4- x - condensation of y (OH) y + yR'OH hydrolyzed alkoxide proceeds according to the following general reaction.

Or Further hydrolysis and condensation follows with condensation with the hydrophilic hydroxybenzotriazole.

The pH and / or the degree of condensation of the alkoxide can be adjusted if necessary. Thereby preventing clouding or precipitation on mixing with organic UV absorbers, preferably ethoxylated or propoxylated hydroxybenzotriazoles, and partially hydrolyzing with the terminal hydroxy groups of the hydrophilic extender chains of the organic UV absorbers. Facilitates the condensation reaction with the formed metal alkoxide. The sol preferably comprises about 0.5 to 5.0 percent by weight solids of hydrophilic hydroxybenzotriazole. Titanium and / or zirconium alkoxides are also included in the compositions of this invention, as are colloidal silicas for abrasion resistance. The UV protection provided by the hydrophilic hydroxybenzotriazole-containing coating of this invention is measured by measuring the UV absorption spectrum of the coating applied on a quartz substrate.

To coat a polycarbonate substrate with the abrasion resistant sol-gel composition of the present invention, the acrylic primer solution shown below is preferably prepared. Thermoplastic acrylic primers are prepared by mixing polymethylmethacrylate and polyethylmethacrylate in an aggressive solvent.
Organic UV absorbers are added to provide UV protection. The addition of flow control agents is preferred. Polymethylmethacrylate and polyethylmethacrylate may comprise a mixture of homopolymers or be copolymerized. Preferably, the composition comprises 60 to 90 percent polymethylmethacrylate.
Contains 10 to 40 percent polyethylmethacrylate. The average molecular weight of the polymer is preferably in the range 80,000 to 350,000 as measured by gel permeation chromatography.

A clean polycarbonate substrate is subjected to the primer solution of this invention, preferably by a dip or a flow down method, and then air dried for about 15 minutes until tack free. Primed plastic substrate then 60-100 for 30 minutes
Dry in oven at ℃.

UV resistant primers that protect substrates such as polycarbonate from the damage caused by UV light are formed by environmentally stable acrylates as the main matrix.
Such polymeric acrylates not only provide significant cross-linking adhesion between the inorganic-based topcoat and polycarbonate, but also provide considerable resistance to hot and humid environments and UV radiation. Acrylic matrices providing a glass transition temperature between 65 ° C. and 105 ° C. are preferred according to the invention. The type of (meth) acrylate unit, the molecular weight of the polymer, the blending method such as blending or copolymerization are selected to provide the optimum properties.

Equally important in this invention is the selection of organic UV absorbers that affect both the efficiency of UV protection and sensitivity to humidity, which is the efficiency and molecular compatibility of the UV absorbers encased in the main acrylic matrix. Depends on. Due to the low molecular miscibility and compatibility between the primer matrix and the UV absorber, the retention of the UV absorber during topcoat application is relatively short, or humidity such that other visible optical fog appears. Less resistant or UV absorber leaches out after short-term use.

The preferred acrylic matrix according to the invention is from 60
90 parts poly (methyl methacrylate) and 40 to 10 parts poly (ethyl methacrylate), preferably 80 to 90 parts poly (methyl methacrylate) and 10 to 20 parts poly (ethyl methacrylate) are mixed in a weight ratio. Made. Alternatively, copolymers corresponding to acrylates and their derivatives can also be fully used as a matrix for UV absorbers in the primers of this invention.

Preferably, the benzotriazole-type UV absorbers can be chosen for better compatibility with the main acrylic matrix as compared to benzophenone-type UV absorbers. The preferred compositions of this invention can have various substituents on the hydroxybenzotriere ring as shown below.

Here, R ₁ and R ₂ are hydrogen, alkyl, aryl and the like.
Preferred UV absorbers of this invention include benzotriazoles of the above type where R ₁ and R ₂ are 1,1-dimethylbenzylphenyl (Tinuvrn 9 from Ciba Geigy).
00), R ₁ is t-butyl, R ₂ is a propionate of polyethylene glycol (Tinuvin 11 from Ciba Geigy).
30), and R ₁ is hydrogen and R ₂ is octylphenyl (Cyasorb 5411 from American Cyanamide).

The present invention will be better understood from the specific embodiments described below.

(5) Example 1 A wear and UV resistant silane / zirconia coating was prepared as follows. An organoalkoxysilane composition was prepared by mixing 25 grams of methyltriethoxysilane and 50 grams of γ-propylacryloxytolumethoxysilane. To the organoalkoxysilane was added 1.8 grams of ethoxylated hydroxybenzotriazole (Tinuvin 1130 from Ciba Geigy). The composition was stirred for 10 minutes and then 30 grams of 2-propanol, 8 grams of deionized water and 5 drops of hydrochloric acid were added to hydrolyze the organoalkoxysilane. The hydrolyzed organoalkoxysilane composition was transparent. To the hydrolyzed organoalkoxysilane was added 30 grams of zirconium n-propoxide. After stirring for 20 minutes, 20 grams of deionized water was added to complete the hydrolysis, along with 6 grams of 10 percent ammonium hydroxide and 10 grams of diacetone alcohol containing 1.2 grams of additional tinuvin 1130. The mixture was stirred at room temperature for 2 hours. Finally 0.5 grams of azoisobutyl nitrile and 5 grams of diacetone alcohol were added.

For comparison, when a hydroxybenzophenone UV absorber was added to such a sol-gel abrasion resistant coating composition, a color change followed by precipitation.

Example 2 Organic UV absorbers with improved miscibility with alcohol-water based inorganic sols are prepared by incorporating water miscible ethoxylated or propoxylated chains with terminal hydroxy groups. I was able to. Hydrophilic substituted hydroxybenzophenones such as 21.4
It was prepared by dissolving grams of 2,4-dihydroxybenzophenone (0.10 mol) and a trace amount of potassium hydroxide in 100 grams of dioxane in a reaction vessel. A solution of 23.2 grams of propylene oxide in 35 grams of dioxane was slowly added to the dioxane solution at 20 ° C over 30 minutes and then raised to 35 ° C for another 30 minutes. The reaction was cooled by adding about 5 grams of water to dioxane. The reaction was collected by precipitating the reaction from the solvent by adding a large excess of water. The miscibility of the displaced product depends on the length of the propoxylation, which is also determined by the molar ratio of propylene oxide and benzophenone.

Examples 3 and 4 The reaction mixture was 100 grams of methyltriethoxysilane (A-162 from Union Carbide), 10 grams of dimethyldiethoxysilane, 60 grams of silica sol (Ludox LS from DuPont), and 3.6 grams of Prepared with acetic acid. The mixture was reacted at room temperature. About 1
After one day of reaction, the mixture was diluted with 80 grams of isobutanol and centrifuged. The mixture was divided into 3 parts, each containing 0,1.5% and a gel weight of β- [3 (2H-benzotriazol-2-yl-) 4-hydroxy-5-t-butylphenyl-] propionic acid. A methyl ester of polyethylene glycol having a molecular weight of 300 was added with 2%. The reaction was continued at room temperature for 3 days.

The primed polycarbonate substrate was immersed in the above solution for about 3 minutes, then dried for 15 minutes and then cured at 120 ° C. for 1 hour. UV resistance was measured by the intensity of UV absorption through a quartz substrate. The adhesive properties of the coating are ASTM D-
3359-87 allows Gardner's 11-tooth scriber (Ga
An rdner 11-tooth scriber) was used for the X-direction cross scribe, and then the tape was pulled three times over 100 scares. Adhesion is said to be excellent when no scare fails.

ASTM F735-81 was used to measure the Bayer abrasion resistance of the coating. A 4 ″ × 4 ″ coated polycarbonate was subjected to a 2 minute 300 abrasion test of a vibrating silica sandbox. Cloudiness meter (Hazegard syste of Pacific Scientific)
The change in the percentage of haze measured by m)) was reported. Polycarbonates not normally coated show an increase in haze of 55-60% in this test.

The UV resistance of the coating itself, as well as the ability to protect the underlying substrate from UV damage, is a fluorescent tube made by Q-Panel Co. Ltd. according to the test method described in ASTM G53-77. B313 nanometers) and placed in an accelerated Q-UV chamber. The chamber was programmed by an 8 hour light cycle at 70 ° C followed by a 4 hour condensation cycle at 50 ° C and 100% humidity. The appearance of the coating was inspected and the fading was determined by the Yellow Index clause (ASTM E308-85,19 using a UV / VIS spectrophotometer).
31 CIE, Illuminant C). Uncoated polycarbonate usually reaches a value of 10 immediately after 100 hours of exposure. The following properties were observed.

Example 5 A reaction mixture containing 80 grams of methyltrimethoxysilane and 8 grams of dimethyldiethoxysilane was prepared, by dissolving 1.5 grams of polyvinylpyrrolidone in 55 grams of methanol and 55 grams of deionized water. The prepared solution was added. After adding 4 grams of acetic acid, the mixture was stirred at room temperature for 2 hours. Then 50 grams of diacetone alcohol and 25 grams of isopropanol were added to the mixture along with 2 grams of Tinuvin 1130, followed by 0.2 grams of potassium acetate. Stirring at room temperature was continued for 3 days.

The cleaned polycarbonate was primed, then soaked in the coating composition solution for 3 minutes, air dried for 15 minutes, and then cured at 120 ° C. for 1 hour. An optically clear UV resistant and abrasion resistant coating was obtained.

Example 6 A solution was prepared by dissolving 1.5 grams of polyvinylpyrrolidone in 55 grams of methanol and 55 grams of deionized water, then 4 grams of acetic acid was added. 80 in that solution
Grams of methyltrimethoxysilane, 8 grams of dimethyldiethoxysilane and 3 grams of the derivative of hydroxybenzophenone propoxylate of Example 2 were added. The reaction mixture was stirred at room temperature for 2 hours, then 50
Grams of 2-propanol, 25 grams of diacetone alcohol and 0.2 grams of potassium acetate were added. The reaction was continued at room temperature for 3 days.

A clean polycarbonate substrate is primed and then flow coated with the above coating composition, air dried and
Cured at ℃ for 1 hour. An optically clear abrasion resistant coating was obtained.

Example 7 A thermoplastic acrylic primer was prepared by dissolving 12 grams of polymethylmethacrylate and 3 grams of polyethylenemethacrylate in 230 grams of propylene glycol methyl ether (Dowanol PM from Dow Chemical Co.) and 20 grams of toluene. 2 grams of Ciasolve 5411
UV absorber was added to provide UV protection. A flow modifier was added (0.01% by weight BYK-300 from West German BYK Chemicals in siloxane-containing polyether).

The cleaned polycarbonate substrate was dipped or flow coated in the primer solution for 2 minutes and then dried for about 15 minutes until tack free. The primed plastic was dried in an oven at 60-100 ° C for 30 minutes.

100 grams of methyltriethoxysilane (A-162 from Union Carbide), 10 grams of dimethyldiethoxysilane, 60 grams of silica sol (Radox L from DuPont)
S), and an abrasion resistant sol-gel coating containing 3.6 grams of acetic acid was prepared. The mixture was reacted at room temperature for 1 day, diluted with 80 grams of isobutanol and then centrifuged. The mixture was divided into two parts, each of which was based on the gel weight, β- (3- (2H-benzotriazole-
2-yl-) 4-hydroxy-5-t-butylphenyl-) propionic acid 0 and 1.5%, respectively, were added together with the methyl ester of polyethylene glycol of molecular weight 300. The reaction was continued at room temperature for 3 days. The primed polycarbonate was immersed in the above solution for 3 minutes at 15 ° C, air dried for 15 minutes, and then cured for 1 hour at 120 ° C.

UV resistance was measured by the intensity of UV absorption through a quartz substrate. The adhesive properties of the coating are according to ASTM D-3359-87,
Gardner 11-tooth scriber
riber) was used for a cross scribe in the X direction and then the tape was measured three times over 100 scares. Adhesion is said to be excellent when no scare fails.

The UV resistance of the coating itself, as well as the ability to protect the underlying substrate from damage by UV, makes the coated polycarbonate a fluorescent tube made by Q-Panel Corporation according to the test method described in ASTM G53-77. B313 nanometers) and placed in an accelerated Q-UV chamber. The chamber was programmed by an 8 hour illumination cycle at 70 ° C followed by a 4 hour condensation cycle at 50 ° C and 100% humidity. The appearance of the coating was inspected and the fading was determined by the yellow index using a UV / VIS spectrophotometer (ASTM E308-85, 1
931 CIE, Illuminant C). Uncoated polycarbonate usually has 10
Reach the value of.

The UV resistance of the primer alone, the abrasion resistant coating with the primer, and the abrasion resistant coating containing the primer and the additional UV absorber is compared in the table below.

Example 8 A primer solution of 90 parts polymethylmethacrylate and 10 parts polyethylmethacrylate was a warm mixture of 24.3 grams polymethylmethacrylate and 2.7 grams polyethylmethacrylate 410 grams Dowanol PM and 133 grams diacetone alcohol. Made by dissolving in. To the above was added a solution of 6.7 grams of Tinuvin 900 UV absorber in 32 grams of toluene. 0.05 grams of BYK-300, a siloxane-containing polyether, was added as a flow modifier to obtain an optically smooth surface.

The abrasion resistant coating mixture consisted of 1.8 grams polyvinylpyrrolidone (PVP K90 from GAF) in 33 grams deionized water and 3.3 grams methanol, 48 grams methyltrimethoxysilane, 4.8 grams dimethyldiethoxysilane. And a mixture of 2.4 grams of acetic acid. After 2 hours at room temperature, the reaction mixture is 30
It was diluted with 2 grams of 2-propanol and 15 grams of diacetone alcohol. Then 0.2 grams of sodium acetate was added and the reaction was continued for 2 days. 0.1g BYK
After adding -300 rheology modifier, the mixture was pH adjusted by ion exchange using 1.8 grams of BioRad cation exchange resin (A6,50W-X8).

A clean polycarbonate substrate was flow coated with the primer solution. After air-drying for about 15 minutes, the primer is further 100 ℃
Dried for 30 minutes. The abrasion resistant coating mixture is flow coated onto the primed polycarbonate and air dried.
It was dried for 15 minutes and then cured at 120 ° C. for 20 minutes. An optically clear coating was obtained.

ASTM F735-81 was used to measure the Bayer abrasion resistance of the coating. A 4 "x 4" coated polycarbonate was subjected to 300 abrasion tests in a vibrating silica sandbox for 2 minutes. Changes in the percentage of haze measured by a haze meter (Pacific Scientific Haze Guard System) were reported. Polycarbonates not normally coated show an increase in haze of 55-60% in this test.

The abrasion resistance, UV resistance and moisture resistance properties are shown in the column of Example 2 in the table below.

Example 9 The polymethylmethacrylate / polyethylmethacrylate mixture of Example 2 was replaced with 27 grams (Polyscience) of a 60/40 ratio copolymer of methylmethacrylate and ethylmethacrylate. The UV resistance and moisture resistance properties are shown in the column of Example 3 of Table 1 together with the properties of Example 8 (column of Example 2).

Example 10 A primer was prepared by adding 5.0 g of a copolymer of methyl methacrylate and ethyl methacrylate (Polyscience) to 65 g of propylene glycol methyl ether.
Prepared by dissolving in a warm mixture of 20 grams of diacetone alcohol. 0 in 5 grams of toluene.
325 grams of Chinuvin 900 and 0.68 grams of Chinuvin 11
A UV absorber solution containing 30 was added. Flow regulator (0.01
% BYK-300) was added to adjust the rheological properties of the coating. This primer formed an approximately 2 μm optically transparent protective layer on the polycarbonate. The results are shown in the column of Example 4 of Table 2.

Example 11 3.45 grams of homopolymer of methyl methacrylate and 0.
A primer solution was prepared containing 44 grams of ethyl methacrylate homopolymer. The mixture was solubilized in 54.2 grams of propylene glycol methyl ether and 17.6 grams of diacetone alcohol. UV absorber solution
0.75 grams of tinuvin 1130 in 7.5 grams of toluene
And made up of 0.41 grams of Chinuvin 900. The results are shown in Table 2.
Example 5 column.

Example 12 For comparison, a primer solution using a homopolymer of polyethylmethacrylate was prepared by dissolving 4.29 grams of polyethylmethacrylate in a hot solvent mixture of 56 grams of Dowanol PM and 17.1 grams of diacetone alcohol. Was prepared. 0.5 gram Chinevin 1130
And a solution of 0.3 grams of Tinuvin 900 in 2.5 grams of toluene was prepared.

A silane-PVP type abrasion resistant coating was prepared by the method described in Examples 8 and 9. The primer was flow coated onto polycarbonate and then dried at 100 ° C. for 30 minutes. Abrasion resistant film is also flow coated and 120 ° C
Cured for 20 minutes. The moisture resistance of the primer coating reflects the compatibility of the organic acrylic matrix and the UV absorber, and the overall moisture resistance is 65.6 ° C and 100% condensation humidification test results are shown in the column of Example 6 in the table below.

Example 13 A silane-alumina type abrasion resistant coating was prepared containing the following ingredients. 62 grams of 5% alumina sol in water, 75 grams of methyltriethoxysilane, 5 grams of dimethyldiethoxysilane, 2 grams of acetic acid, 18 grams of diacetone alcohol and 18 grams of 2-propanol.

Clean polycarbonate was primer coated with the solution prepared in Example 11 and dried at 100 ° C for 30 minutes. The silane-alumina solution was flow coated onto the surface of a primed polycarbonate, air dried for 15 minutes and then cured at 120 ° C for 2 hours. The coated polycarbonate exhibited excellent abrasion resistance, 8.0 percent haze after 300 cycles of Bayer abrasion test, and only 3.0 YID yellowing after 700 hours of Q-UVB exposure. No haze appeared on the coating after 1200 hours exposure to 65.6 ° C, 100% relative humidity.

The embodiments described above are provided to illustrate the present invention. Various hydrolyzable alkoxides and hydrophilic hydroxybenzophenones and / or hydroxybenzotriazole compositions have sufficient alkoxides to form an oxide network therein, and measured by UV absorption spectra of coatings on quartz substrates. When combined, a wide range of ratios and concentrations can be combined so long as there is sufficient hydrophilic UV absorber to provide the desired improvement in UV resistance without compromising the abrasion resistance of the coating. Various organic polymers and organic UV absorbers can be combined in a wide range of ratios and concentrations with various aggressive solvents such as aromatic solvents such as xylene to enhance adhesion to organic substrates. In accordance with the present invention, these coatings are useful on a variety of substrates and with a variety of abrasion resistant coatings, the scope of which is defined by the appended claims.

Front Page Continuation (72) Inventor Robert Mikulhania Pea, Kittanning, PA, USA. Oh. Box 46, All. Dee. 7 (72) Inventor Gary John Marietti Box 56, Richhill Estates, Richhill Road (No Address), Cheswick, Pennsylvania, USA (56) Reference JP-A-55-160033 (JP, A) JP-A-62- 172071 (JP, A)

Claims (15)

[Claims] 1. An optically transparent coating composition for protecting a substrate from ultraviolet radiation, comprising: Partially hydrolyzed alkoxide of the general formula RxM (OR ') z _- x. In the formula, R is an organic radical, M is silicon,
Selected from aluminum, titanium, zirconium, cerium and mixtures thereof, R'is a low molecular weight alkyl radical, z is the valence of M and x is less than z or may be zero. b. A hydroxy-containing organic UV absorber having a hydrophilic moiety selected from the group consisting of ethoxylates and propoxylates. 2. A composition according to claim 1, wherein said alkoxide comprises the general formula RxSi (OR ') _4- x and R'is from the group consisting of methyl, ethyl, propyl and butyl. R is selected from alkyl, vinyl, phenyl, methoxyethyl, γ-glycidoxypropyl and γ.
A composition selected from the group consisting of methacryloxypropyl and wherein x is 1. 3. A composition according to claim 1, wherein the hydroxy-containing organic UV absorber is either hydroxybenzotriazole or hydroxybenzophenone. 4. A method of preparing an optically clear UV resistant coating composition comprising the steps of: a. At least partially hydrolyzing an alkoxide of the general formula RxM (OR ') z _- x. Wherein R is an organic radical, M is selected from the group consisting of silicon, aluminum, titanium, zirconium, cerium and mixtures thereof, R'is a low molecular weight alkyl radical and z is the valence of M. And x is less than z and may be zero. b. Adding a hydroxy-containing organic compound that absorbs UV light and includes a hydrophilic moiety to the at least partially hydrolyzed alkoxide described above. 5. The method of claim 4 wherein the alkoxide comprises the general formula RxSi (OR ') _4- x and R'is selected from the group consisting of methyl, ethyl, propyl and butyl. R is alkyl, vinyl, phenyl,
Selected from the group consisting of methoxyethyl, γ-glycidoxypropyl and γ-methacryloxypropyl,
And a method wherein x is 1. 6. The method according to claim 4, wherein the hydroxy-containing organic compound comprises hydroxybenzotriazole or hydroxybenzophenone having a hydrophilic moiety selected from the group consisting of ethoxylates and propoxylates. A method characterized by the following. 7. An optically transparent, UV resistant and abrasion resistant coated article comprising: a. a transparent solid polymer substrate, b. a UV-resistant and abrasion-resistant coating which is the reaction product of the hydrolysis polycondensation of metal alkoxides of the general formula RxM (OR ') z _- x, and UV. A hydroxy-containing organic compound that absorbs. However, in the above general formula, R is an organic radical, M is selected from the group consisting of silicon, aluminum, titanium, zirconium, cerium and mixtures thereof, R'is a low molecular weight alkyl radical, and z is a valence of M. And x is less than z and may be zero. 8. The article according to claim 7, wherein R '
Is selected from the group consisting of methyl, ethyl, propyl and butyl, R is selected from the group consisting of alkyl, vinyl, phenyl, methoxyethyl, γ-glycidoxypropyl and γ-methacryloxypropyl, and x is 1 The article, wherein the substrate is polycarbonate. 9. The article according to claim 8, wherein the hydroxy-containing organic compound contains a hydrophilic moiety selected from the group consisting of ethoxylates and proxylates, and hydroxybenzophenone and hydroxybenzotriazole. An article characterized by being selected from the group consisting of. 10. An optically transparent coating composition for protecting a plastic substrate from ultraviolet light, comprising: a hydroxy-containing compound selected from the group consisting of hydroxybenzophenones and hydroxybenzotriazoles b. a mixture of thermoplastic polymers of alkyl acrylates and a polymer selected from the group consisting of thermoplastic polymers of alkyl acrylates or their derivatives c. propylene Solvents containing glycol methyl ether 11. A composition according to claim 10, which comprises:
A composition characterized in that the solvent further comprises toluene. 12. An optically transparent, UV resistant coated article comprising: an optically polymerized substrate, b.1) a hydroxy-containing compound selected from the group consisting of hydroxybenzophenones and hydroxybenzotriazoles 2) a mixture of thermoplastic polymers of alkyl acrylates and thermoplastics of alkyl acrylates or derivatives thereof A transparent UV resistant coating comprising a film forming polymer selected from the group consisting of copolymers. 13. The article according to claim 12, wherein the substrate is polycarbonate. 14. Article according to claim 12, wherein the film-forming polymer comprises poly (methylmethacrylate) or poly (ethylmethacrylate). 15. The article according to claim 12, further comprising an abrasion resistant coating which is the reaction product of a hydrolytic polycondensation of a metal alkoxide.