CA1229445A - Solventless u-v light-curable hard coating compositions - Google Patents

Abstract

SOLVENTLESS U-V LIGHT-CURABLE
HARD COATING COMPOSITIONS

ABSTRACT OF THE DISCLOSURE
An ultraviolet radiation-curable silicone coating composition is disclosed which, when applied to a solid substrate, provides an abrasion-resistant coating firmly adhered thereon. The silicone coating composition is free of residual solvent and free of toxic hydroxy acrylates, and is prepared from the hydrolysis products of acryloxy-functional silanes and/or glycidoxy-functional silanes, colloidal silica and a photoinitiator.

Description

I

SOLVENT LESS U-V LIGHT-CURABLE
HARD COATING COMPOSITIONS
BACKGROUND OF THE INVENTION
This invention relates to a solventiess ultraviolet radiation-curable protective coating composition. More particularly, it relates to a silicone coating composition which contains no water or organic solvent and, when applied to a substrate, may be quickly cured by exposure to US
radiation to form a protective abrasion-resistant coating thereon.
Recently, the substitution of glass glazing with transparent materials which do not shatter or are more resistant to shattering then glass has become widespread.
For example, transparent glazing made from synthetic organic polymers is now utilized in public transportation vehicles such as trains, buses, taxis and airplanes. Lenses for eye glasses and other optical instruments, as well as glazing for large buildings, also employ shatter-resistant, transparent plastics. The lighter weight ox these plastics in comparison to glass is a further advantage, especially in the trays-partition industry where the weight of the vehicle is a major factor in its fuel economy.
While transparent plastics provide the major advantage of being morn resistant to shattering and lighter than glass, a serious drawback lies in the ease with which these plastics mar and scratch, due to I everyday contact with abrasives, such as dust, cleaning equipment and/or ordinary weathering. Continuous scratching and marring results in impaired visibility `;' US
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and poor anesthetics and often requires replacement the glazing or lens or the like.
One of the most promising and widely used transparent plastics for glazing is polycarbonate, such as that known as Lean I, sold by General Electric Company. It is a tough material, having high impact strength, high heat deflection temperature and good stability. It is also self extinguishing and it is easily fabricated Acrylics, such as polymethylmeth-acrylate, are also widely used transparent plastics for glazing.
Attempts have been made to improve the abrasion resistance of transparent plastics. For example, scratch-resistant coatings formed from mixtures of silica, such as colloidal silica or silica gel, and hydrolyzable sullenness in a hydrolysis medium such as alcohol and water-, are known. US. Patents 3,708,225, issued January 2, 1973 to Mesh et at; 3,986,997, issued October 19, 1975 to Clark; 3,976,497, issued August I 1976 to Clark and 4,027,073, issued May 31/ 1977 to Clark, for example, describe such compositions.
In Canadian Patent Application Serial No. 339,S39, wiled November 9, 1979, coating compositions having improved resistance to moisture and humidity and ultra-violet light are disclosed. It was discovered therein that, in direct contrast to the -teachings of Us Patent 3,986,997, composi-tiorls having a basic phi i.e.
7.1-7.8, do not immediately gel but in fact provide excellent abrasion-resistant coatings on solid substrates.
Recent discoveries offer a significant advantage over many of the heretofore known silicone coating compositions in that they do not require heat in order to initiate ho cure reaction. Instead, ultraviolet radiation is employed, expending considerably less thermal energy than conventional heat cure systems.

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See, e.g., US. Patent No. 4,310,~00, issued January 12, 1982.
Ultraviolet light is one of the oust widely used types ox radiation because of it relatively low cost, ease of maintenance, and low potential hazard to industrial users. Besides avoiding high temperature cure environments, rapid photv-induced polymerizations Jo utilizing Us light for curing hard coat go offer "`~ several other significant advantages. , the cure time is much shorter, leading to substantial economic benefits. Second, heat sensitive materials can be safely coated and cured with US light without the use of thermal energy which could damage the substrate.
Additionally, the lower levels of solvents reduces the necessity for expensive and time-consuming pollution abatement procedures.
Although it is known that colloidal silica can be incorporated into heat cured coating systems, applicant has discovered that such colloidal silicas can be utilized to improve the abrasion resistance of ultraviolet light-curable coatings. Cop ending Canadian Patent Application Serial No. 376,679, filed Jay 1, 1981, discloses a radiation-curable hard-coating composition which requires the use of the acid hydrolysis product of an alkoxy functional Solon. US. Patent Number 4,348,462, issued September 7, 19~2, provides W-curable coatings which possess even greater abrasion resistance and yet do not require the use of alkoxy sullenness; these results are accomplished -through the specific combination of colloidal silica with acrylics functional sullenness or water miscible hydroxy acrylates, or preferably both, with catalytic amounts of US sensitive photo-initiators.
The Uncurable coating compositions of the present invention improve upon the adhesion, abrasion resistance and resistance to yellowing on exposure to W-radiation offered by the aforementioned compositions.

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In addition, the instant compositions are essentially solvent-free, and the use of highly toxic hydroxy-functional acrylates is eliminated. Also eliminated from the instant compositions is free water, itch increases shipping weight and necessitates added drying time before curing.
SUMMERY Of' THE INVENTION
Accordingly, it is one object of the present invention to provide a novel protective coating for solid substrates, Another object of -this invention is to provide a radiation-curable coating for solid substrates which, when applied to the substrate, provides an improved abrasion-resistant surface thereto.
Another object of the present invention is to provide a W-curable coating composition which is essentially solvent-free and avoids the use of toxic hydroxy acrylates.
Still another object of the present invention zoo is to provide a silicone coating composition especially well-suited for providing an improved abrasion-resistant surface to transparent substrate without impairing the optical clarity of the substrate, A further object ox the present invention is to provide a coating composition which results in an improved abrasion-resistant surface when applied to metals and metallized surfaces, These and other objects are accomplished herein by a solvent less ultraviolet radiation-curable coating composition comprising:
(A) 100 parts ho weight silica in the form of a colloidal dispersion;
(B) 5 to 500 parts by weight of the acid hydrolysis product of (i) an acryloxy-fun~tional Solon or the formula:

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o R6 (R Obeyer - So (R -O-C-C=CH2)d wherein R3 and R4 are the same or different monovalent hydrocarbon radicals, R5 is a diva lent hydrocarbon radical having from 2 to 8 carbon atoms, I is hydrogen or a monovalent hydrocarbon radical b is an integer from 1 to 3, c is an integer from 0 Jo 2, and d is an integer equal to 4-b-c; or (ii) a glyeidoxy-funetional Solon of the formula:

(R eye Of - So (R -O-CH2-HC\ / Shag wherein R7 and R8 are the same or different monovalent : hydrocarbon radicals, R is a diva lent hydrocarbon radical having from 2 to 8 carbon atoms, e is an integer from 1 to 3, f is an integer from 0 to 2, and g is an integer equal to 4-e-f; or (iii) mixtures of (i) and (ii); and (C) a catalytic amount of an ultraviolet light sensitive photo initiator In other features, the coating compositions of : 20 the present invention will additionally contain 10-S00 parts by weight of a non-silyl aerylate. These compounds have been wound to dramatically increase adhesion and abrasion resistance of the cured product when used in conjunction with colloidal silica.
In other features, the compositions will also contain photo-modifiable compounds which, while allowing the coating composition to cure on exposure to ultraviolet radiation, are structurally modified by the radiation to form ultraviolet screening compounds. This structural I

~0~I-3~2 change known as "Fries rearrangement", gives the cured coating and substrate added protection against trio cracking, yellowing or delamination effects associated with prolonged ultraviolet light exposure.
DETAINED DESCRIPTION OF THE INVENTION
The coating compositions of this invention are prepared by thoroughly admixing the silica and Solon components and then removing solvents under reduced pressure. Optional acrylate components and curing catalysts are then added to form coating compositions which may be applied directly to a substrate, such as polyester film, and then cured in one pass of W radiation in a matter of seconds to yield adherent, abrasion-resistant coatings.
The silica components should be in the form of a silicon dioxide (Sue) dispersed in solvents. For example, Nalco 1034 is a dispersion of 34~ Sue and 66% water by weight. Colloidal silica is available in basic or acidic form. Either may be utilized; however, the acidic form (low sodium content) is preferred.
; To the colloidal silica is added S to 500 parts and preferably 50 to 200 parts of an acrylics functional Solon or glycidoxy functional Solon, or a mixture of both types of sullenness. The sullenness help impart high abrasion resistance to the coating compounds. It has been found, however, that with sullenness and colloidal silica alone, adhesion may be poor. To improve adhesion, there may be added, to the acrylics and glycidoxy functional sullenness, from 10 to 500 parts, preferably 50 to 200 parts, of a non-silyl acrylate material. Especially preferred acrylates fur the purposes herein are non-hydroxy acrylates. Non-hydroxy acrylates are utilized because they are less toxic and as miscible in water as the hydroxy acrylates. In the solvent less systems of this invention, any water or other solvent remaining after mixing the ingredients is removed.

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The above-described ingredients are catalyzed with catalytic amounts of ultraviolet light sensitive photo initiators or blends of such initiators. Radical-type initiators can be utilized alone, but employing a combination of radical and cat ionic photo initiators results in improved abrasion resistance. In fact, when acidic colloidal silica is used, it is essential that such a combination of photo initiators be used. The radical-type catalysts are used to cure the acrylics functional portions of the compositions whereas the cationic-type catalysts cure the selection portions.
The catalytic amounts of these pnotoinitiators may vary but ordinarily the cationic-type catalyst, such as the hereinafter-described opium salts, will be present in an amount of, approximately, 0.05 to 5.0~ by weigh-t based upon the amounts of ingredients A, B, and non-silyl acrylate (if present), and preferably will be present in an amount of from 0.1 to 1.5~ by weight. The radical-type photo initiators will ordinarily be present in an amount of, approximately, 0.5 to 5.0~ by weight of ingredients, A, B, and non-silyl acrylate (if present).
and preferably will be present in an amount of, approximately, 1.0 to 3.0% by weight.
The second major component of the present compositions is the acid hydrolysis product ox an acryloxy-functional Solon or the acid hydrolysis product of a glycidoxy-functional Solon or mixtures thereof The acryloxy-functional Solon has a general formula (I) (Rob R4 - Syria - o - f I = I

wherein R3 and R4 are the same or different monovalent hydrocarbon radicals, including halo~enated species of such radicals. Preferably, R3 an R4 will be lower alkyd f radicals such as methyl, ethyl, propel, etc., but they may also be other saturate and unsaturated species including vinyl, aureole, etc. I is a diva lent hydra-carbon radical having from 2 to 8 carbon atoms. R6 is a hydrogen or a monovalent hydrocarbon radical. The letter b is an integer from 1 to 3, c is an integer from 0 to 2 and d is an integer equaling 4-b-c. In many of the embodiments of the present invention, b ordinarily be 3, c will be 0 and d will equal 1.
Specific examples of acryloxy-functional sullenness contemplated herein include:
3-methacryloxypropyltrimethoxysilane 3-acryloxypropyltrimethoxysilane

2-methacryloxyethyltrimethoxysilane 2-acryloxyethyltrimethoxysilane

3-methacryloxypropyltriethoxysilane 3-acryloxypropyltriethoxysilane 2-methacryloxyethyltriethoxysilane 2-acryloxyethyltriethoxysilane Such acryloxy-functional sullenness are commercially available.
3-methacryloxypropyltrimethoxysilane, for example, may be obtained from Union Carbide.
The second, or Solon, component of the coating composition may also be a glycidoxy-functional Solon instead of an acryloxy-functional Solon, or it may be a combination or mixture of both types of sullenness. A
glycido~y-functional Solon has the general formula tip) (R eye Of - Six R - O - SHEA -HO Hug wherein R7 and I are the same or different monovalent hydrocarbon radicals as described above for R and R , R9 is a diva lent hydrocarbon radical having from 2 to 3 carbon atoms, the letter e it an integer from 1 to 3, f is an integer from to 2 and g is an integer equaling , I 3~2 go

4-e-f Specific examples of useful glycid~xy-functional sullenness include the following:
3-glycidoxypropyltrimethoxysilane 2-glycidoxyethyltrimethoxysilane 3-glycidoxypropyltriethoxysilane 2-glycidoxyethyltriethoxysilane These glycidoxy-functional sullenness are also commercially available, for example, from Tetrarch Systems, Inc.
The optional third-component (c) of these hard coating compositions is a non-silyl acrylate compound.
Such compounds have been found to dramatically increase the abrasion resistance of the cured product when used with the colloidal silica described above. These acrylate compositions are considered to be non-silyl functional to distinguish them from the acrylics functional sullenness described above. They are esters of acrylic acid, and the most preferred are non-hydroxy acrylates.
Among the acrylates which may be utilized in the present invention are:
diethylene glycol diacrylate triethylene glycol diacrylate tetraethylene glycol diacrylate trimethylol propane triacrylate tetrahydro furfuryl methacrylate 1-6-hexanediol ~iacrylate Any solvent remaining or venerated after thorough admixture of the components must be removed, preferably before the addition of the catalyst described hereinafter.
This is preferably done in vacua or at reduced pressure with gentle heating, e.g., to about 40 C.
To the mixture of the first two or three components must be added a catalytic amount Of I a photo initiator. Effective photo initiators are radiation sensitive aromatic halonium, sulfonium or phosphonium salts all of which are described in the literature.

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Cat ionic photo initiators are described in numerous US. Patents, such as the following, US.
Patent No. 4,136,102, issued January 23, 1979 to Crivello and 3,981,897, issued September 21, 1976 to Crivello. Such cat ionic photo initiators can have the general formula (III) (R - Cohn X McKee In this formula, X is a radical selected from I, P or S.
M is a metal or metalloid and Q is a halogen radical selected from Of, F, Bra or I. R is hydrogen or a monovalent hydrocarbon radical having from 1 to 12 carbon atoms. h is an integer having the value of 4 to 6 inclusive, and n is an integer having the value of 2 or 3.
The expression McKee applies to any number of ionic species but preferably will be selected from SbF6 , AsF6 , BF4 and Pi Particular cat ionic catalysts include diphenyl iodonium salts of tetrafluoro borate, hexfluoro phosphate, hexafluoro arsenate, and hexafluoro antimonate; and ~riphenyl; sulfonium salts of tetrafluoro borate, hexafluoro phosphate, hexafluoro phosphate, hexafluoro arsenate, and hexafluoro antimonate.
It is ordinarily preferable to utilize approximately 0.1 to 1.5 parts by weight of the cat ionic photo initiator for every 100 parts by weight of the mixture of ingredients A, B and a non-silyl acrylate as described above. However, depending upon individual desired process parameters such as rate of cure and ultimate abrasion resistance, the amount of the photo initiator can range from approximately .05 to 5 parts by weight per 100 parts of the mixture of ingredient A, I, and optionalnon-silyl acrylate.
These cat ionic photo initiators are particularly effective for initiating a cross-linking reaction upon exposure to ultraviolet radiation. Good hard coatings SUE

having excellent adhesion can thus be obtained -ennui a coating composition of this invention is applied to a substrate and exposed to radiation such as that provided by US lamps.
Improved abrasion resistance can be obtained with the same hard coating compositions when, in addition to the cat ionic photo initiators described above, there is also utilized a radical-type initiator which is effective for cross-linking of sel~-condensing the acryloxy-functional portions of the sullenness contained in the composition.
Such radical photo initiators include among others, Bunsen ethers, alpha-acyloxime esters, acetophenone derivatives, -ensoul petals and kitten amine derivatives. specific examples of these photo initiators include ethyl Bunsen ether, isopropyl Bunsen ether, dimethoxyphenyl acetophenone, and diethoxy acetophenone.
The mixed components A, B, and C can be effectively catalyzed to form satisfactory radiation-curable hard coatings by combining 100 parts by weight of such products and mixtures with from, approximately Owe to 5.0 parts by weight of a combination of photo-initiators. The photoinitiatorcombination will be comprised, of approximately, 10 to 90~ by weight of a cationic-type initiator, such as diphenyl-iodonium-hexafluoroarsenate, and the remaining portion is aradical-type initiator such as ethylbenzoin ether.
Other additives and modifying agents, such as thickeners, pigments, dyes and the like, may also be added to the coating compositions of the present invention, preferably before the addition of the catalyst. A
particularly desirable additive has been found to be a small amount of a polysiloxane polyether copolvmer flow control additive. It has been found that these compounds have a beneficial effect in preventing the occurrence of undesirable flow marks and dirt marks which sometimes occur with the application of the coating composition to a substrate. particularly useful polysiloxane US

polyether copolymer for the purposes herein is Newton as SF-1066, available from the General Electric Company; another is BUICK, sold by Mallinkrodt. The preparation, further description and structural formulae for these polysiloxane polyether copolymers are described in US. Patent No. 3,629,165. Generally, the polysiloxane polyether copolymers are employed in amounts of from about 2.5% to about 15% by weight of the total solids content of the composition.
Also useful as adults to the present coating compositions are photo-modifiable compounds which undergo a reaction known as "Fries rearrangement" to form W -screening compounds. Such compounds are structurally modified by US radiation energy, and the modified compounds themselves screen W radiation. For example, compound IV (below) having the structure (IV) OKAY

O - C - - OH N - C - O

will convert via photo-induced "Fries rearrangement" to Compound V having the structure (V) O OH Me Me ye O , SHEA, c Our which is a Us greener rj Such photo-modifiable compounds are an important discovery in the art of W -curable coatings, because they provide a means of introducing TV screening -materials into w-curable coating compositions and thereby enhancing the weather ability, or resistance to cracking, yellowing and delamination, in the final cured coating. Obviously, incorporating conventional W screens into Uncurable compositions will hinder the cure. Incorporating photo-modifiable compounds into the instant compositions, however, will permit the curing process while at the same time converting to diminish the harmful effects of W radiation on the cured coating.
Photo-modifiable compounds contemplated for use as disclosed herein include compound (IV) above, and also o - !
If . I
okay ' O

O - Ill - NH - OH - C
O Me No - C - O

O

ye My OOZE

O C ', Me Me Me If 2 C - O - I C~2 0 - 8C - C~=C~
O ye If O I
O - C -No - SHEA I - OH
Me N~-C-O-CH2 C~2 O-i if i okay ~0--C--N8--C112~8~0-C~.2 C82 I
o A W -curable coating composition of the present invention is ordinarily coated on at least one surface ox some solid substrate. The solid substrate may be comprised OX
a synthetic organic polymer or metal or even glass, or a synthetic organic polymer substrate which has a metallized surface.
Prior to the composition being coated on a substrate there my optionally be included a priming step wherein a primer such as a thermosetting acrylic emulsion is first applied to the substrate. After the coating composition is applied to the substrate or the primed substrate, the coating may be cured thereon by an I
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effective amount of W-radiation, such as that emitted, for example from a Hanovia 550-watt lamp or a PUG
Processor Model ~C1202.
The coating compositions of the present invention can be applied to a variety of solid substrates by conventional methods, such as flowing, spraying or dipping, to form a continuous surface film. Optimum coating thicknesses are obtained by slow dip coating procedures. Substrates which are especially contemplated herein are transparent and non-transparent plastics and metals. More particularly, these plastics are synthetic organic polymeric substrates such as acrylic polymers like poly(methylmethacrylate); polyesters, such as poly(ethyleneterephthalate), poly(butylene turf-thalate), etc.; polyamides, polyamides; acrylonitrile-styrenes copolymers; styrene-acrylonitrile-butadiene copolymers polyvinyl chloride; butyrates; polyethylene and the like. The coating compositions of this invention are especially useful as coatings for polyester films, polycarbonates, such as poly(bisphenol-A
carbonate) and those polycarbonates known as Lean (sold by General Electric Company); and as coating for injection molded or extruded acrylics, such as polymethylmethacrylates. Metal substrates on which the present protective coatings are also effective include bright and dull metals like aluminum and bright Matilda surfaces live sputtered chromium alloy.
Other solid substrates contemplated herein include wood, painted surfaces, leather, glass, ceramics and textiles.
By choice of the proper formulation, application conditions and pretreatment of the substrate, including the use of primers, the coatings can be adhered to substantially all solid substrates. A hard coating having all of the aforementioned characteristics and advantages is obtained by exposure of the coated substrate to ultraviolet radiation for a period sufficient to induce :

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the cross-linking and condensation (and Fries rearrangement it photo-modifiable compound are employed associated with full cure.
Coating thicknesses may vary, but for improved abrasion resistance coating thicknesses of 3-1~ microns, preferably about 5 microns, are utilized. In the following examples %H500 is a quantitative measure of haze on coated products according to the Tuber Abrasion Resistance Test.
In order that those skilled in the art may better understand how to practice the present invention, the following examples are given by way of illustration and not by way of limitation.

A mixture of 100 parts by weight colloidal silica (Nalco aye ) and 300 parts by weight 3-methacryloxypropyltrimethoxysilane (MPTMS) and 150 parts by weight isopropyl alcohol was reflexed for 30 minutes. After cooling to room temperature, solvents were removed under reduced pressure. The solvent-free hydroly~ate was combined with 5 parts by weight of ¢, ~-diethoxyacetophenone and 3 parts by weight triphenyl sulfonium hexafluoroarsenate. This composition was coated to a thickness of 0.5 miss on a Lean panel, which was then passed through a PUG yodel QC1202 TV
processor under a nitrogen atmosphere at 50 psi with a conveyor speed of 20 ft./min. One pass through the system resulted in a coating which was hard and hazy.

A mixture of 100 parts by weight colloidal silica, 223 parts by weight MPTMS and 150 parts by weight isopropyl alcohol was stirred at room temperature for 3 hours. 71 parts by weight of 3-glycidoxypropyl-trimethoxy Solon (GPTMS) were then added. After stirring at room temperature for 3 hours, solvents were removed in awoke. To the thick resin were added 69 parts by weight diethyleneglycoldiacrylate (DAGWOOD) and 69 parts by weight of trimethylol propane triacrylate (T~lPTA).

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Next were added 4 parts by weight of triphenyl sulfonium hexafluoroarsenate and 8 parts by ,7eight diethoxyacetophenone (DEEP), followed by 2 parts by weight BUICK flow control agent. A film of about 0.11 miss was applied to a Lean panel which was passed through a W processor as in Example l.
The coated Lean panel alas tested for abrasion resistance on a Tuber Abrader, which involves measuring the increase in haze (OH) after being subjected to 500 cycles of abrasive CFlO wheels.
Coating adhesion was also tested, using the crosshatch adhesion test, involving scribing a crisscross pattern (grid) on the coated surface, applying the 710 Tape and pulling it away. 3 tape pulls with no adhesion loss is considered passing. The following results were observed:

No Silicone %Acrylates~ OH_ Adhesion O O
l lo - Hazy Fail 2 66 34 8.5 Pass 3 50 50 8.2 Pass 4 33 67 7.7 Pass 7.6 Pass 6 20 80 7.3 Pass A mixture of lo parts by weight MPTMS and 250 parts by weight GPTMS was added drop-wise to lo parts by weight colloidal silica at room temperature.
The mixture was then stirred at room temperature for 14 hours. The resultant mixture was concentrated under reduced pressure at 40C, at which time 3 parts by weight of triphenyl sulfonium hexafluoroarsenate and 3 parts by weight DEEP were added. This composition was coated on polyester film a-t 7 miss thickness and cured in a PUG 1202 US processor by l pass at 20 fpm/200W to yield a clear hard coating.

~S~-3~2 E~AM2LES 4-9 A mixture of 40 parts by weight of colloidal silica and 40 parts by weight of MPTMS and 80 parts by weight of GPTMS was stirred at room temperature for 2 hours. The organic volatile were then removed under reduced pressure at 40C. 0.4 parts by weight of bus (p-isopropylphenyl)iodoniumhexafluoroarsenate, 0.4 parts by weight of diethoxyacetophenone and 0.5 parts by weight of a polymer were added to the clear silicone residue. The mixture was then coated on polyester film at 7 miss thickness and cured on a PUG QC 1202 US
processor with 1 pass at 20 fpm/300W in an air atmosphere.
Excellent falling sand an steel wool abrasion resistance were obtained.

Another composition was prepared following the procedure of Example 4 using the following ingredients and proportions:
Ingredients Proportion colloidal silica 20 parts by weight MPTMS 20 parts by weight GPTMS 50 parts by weight bis(p-isopropylphenyl)hexa- 0.3 parts by weight fluoroarsenate DEEP 0.5 parts by weight acutely acetone 2.0 parts by weight A clear abrasion resistant coating was obtained.

Another composition was prepared following the procedure of Example 4 using the following ingredients and proportions:

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Ingredients Proportion colloidal silica 100 parts by weight MPTMS 200 parts by weight GPTMS 500 parts by weight Di-toluyl iodonium 3.6 parts by "eight hexafluoroarsenate DEEP 5.0 parts by weight polysiloxane 0.5 parts by weight A clear abrasion-resistant coating was obtained.

Another composition was prepared following the procedure of Example 4 using the following ingredients and proportions:
Ingredients Proportion .

colloidal silica 150 parts by weight MPTMS 200 parts by weight GPTMS 500 parts by weight Di-toluyl iodonium 4.0 parts by weight hexafluoroarsenate DEEP 5.0 parts by weight polysiloxane 0.8 parts by weight A clear abrasion-resistant coating was obtained.

Another composition was prepared following the procedure of Example 4 using the following ingredients and proportions:

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Ingredients Proportion colloidal silica 100 parts by weight MPTMS 100 parts by weight GPTMS 400 parts by weight

5 Triphenyl sulfonium 3.0 parts by weight hexafluoroarsenate polysiloxane 0.8 parts by weight acutely acetone 5.0 parts by weight A clear abrasion-resistant coating was obtained.

Another composition was prepared following the procedure of Example 4 using the following ingredients and proportions:
Ingredients Proportion 15 colloidal silica 100 parts by weight MPTMS 150 parts by weight ~-~3.4-epoxycyclohexyl)- 400 parts by weight ethyltrimethoxysilane Diphenyliodoniumhexafluoro- 3.5 parts by weight arsenate DEEP 4.5 parts by weight polysiloxane 0.9 parts by weight A clear abrasion-resistant coating was obtained.

A composition was prepared following the procedure of Examples 1 and 2 using the following ingredients and proportions Ingredients Proportion colloidal silica 200 parts by weight 30 MPTMS 600 parts by weight isopropyl alcohol 300 parts by weight I
65~I-382 The following results were observed:

No. Silicone % Acrylates% Ph3S ASF6 DEEP owe ( % ) (_ I 100 0 0.5 assay II 66 34 0.4 0.611.0 III50 50 0.3 0.89.Q
IV 33 67 0.2 1.06 9 V 25 75 0.1 1.26.4 A composition was prepared following the preparation of Example 2 using the following ingredients and proportions:
Ingredients Proportion colloidal silica 100 parts by weight 15 MPTMS 149 parts by weight GPTMS 142 parts by weight DEEP 70 parts by weight TMPTA 70 parts by weight The following results were observed:
2Q No. Silicone % Acrylates Ph3S ~sF6 DEEP 500 (%) (I
_ I 100 0 0.2 pyre adhesion) II 66 34 Al 0.2 5.2 III 50 50 0.1 0.2 5.3 IV 33 67 0~1 I 7.3 25 V US 76 0.1 0.2 7.7 VI 20 80 0.1 0.2 8.0 To test the effect of photo-modifiable UV-screener precursor compounds in coatings of this type, Compound IV, I
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shown above, was synthesized as follows:
To a mixture of 1/2 mol. of isophoronediiso-Senate and 1 mol. of resorcinol monobenzoate and 500 ml.
of dry tetrahydrofuran was added, drop-wise, 1 mol. of triethylamine. The temperature was maintained below 40 C. After stirring overnight, the resulting mixtllre was concentrated under reduced pressure to rummage the tetrahydrofuran and triethylamine. The crude product was passed through a short silicone column and eluded with ethyl acetate, to yield a thick, clear Compound IT
An experimental coating composition was also prepared, as follows:
To 175 parts by weight colloidal silica was added, drop-wise 165 parts by weight MPTMS over a period of 40 minutes at room temperature. The mixture was stirred for 16 hours at room temperature. Excess water and solvents were removed under reduced pressures with the aid of pure isopropyl alcohol. The clear hydrolyzate was then treated with basic ion exchange resin ~Amberlite ROY . The organic solvents were again removed, and 72 parts by weight DAGWOOD and 72 parts by weight of TMPrrA were added. Thereafter, 6.4 parts by weight benzophenone and 5.4 parts by weight me-thyldiethanolamine (radical catalysts) were added.
Compound IV was added to the experimental composition in varying amounts, then coated on Lean and cured on a PUG 1202 W processor with 1 pass at 20 fpm/300W in an air atmosphere to yield the following results:
30 No. % Coup. IV H500 QUA
1 0 3.0 20 his. cracks 2 3 3.2 1~3 3 6 4.9 153 4 9 5.4 189 12 5.5 300

6 15 5.7 300 I., to - 23 - 6~S~-38 To a mixture of 29.0 parts by weight o, methyl-resorcinolmonobenzoate and 100 ml. of an hydrous tetrahydro-Furman was added 0.2 parts by weight of dibutyltindilaurate and 14 parts by weight of isophoronediisocyanate at room temperature. After stirring for 17 hours the solvent was removed to yield Compound VI shown below:
(VI) I ox O - C - N SHEA Nil C -H Me The Compound VI was then tested in a coating composition obtained from 45% silicone resin and 55%
acrylates. The results are shown below:

1000 QUA (his.) Compound VI Air-Cure N2-Cure Air-0 4.3 11.1 336 336 3 2.5 11.0 361 404 6 5.7 8.5 473 473 g 3.5 8.7 527 573 12 4.0 9.7 7~5 640 A composition was prepared following the procedure of Example 13 using the following ingredients and proportions:

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Ingredients Proportion colloidal silica 520 parts Dye weight MPTMS 100 parts by weight phenyltrimethoxysilane 10 parts by weight 5 diethyleneglycoldiacrylate 33 parts by weight TMPTA 32 parts by weight benzophenone 8 parts by weight methyldiethanolamine 8 parts by weight - Compound VI was added to the coating in varying amounts, and the following data after US cure on polycarbonate plaques (20 fpm in an air atmosphere) were obtained:
% Compound VI Lowe US (his.) 0 4.7 58 15 3.0 4.5 58 I 4.9 167 9.0 5.2 222 12.0 5.5 336 15.0 5.7 534 Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious modifications are within the full intended scope of the appended claims.

,....

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Claims (28)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A solventless ultraviolet radiation-curable coating composition free of hydroxy acrylates comprising:
(A) 100 parts by weight silica in the form of a colloidal dispersion;
(B) 5 to 500 parts by weight of an acid hydrolysis product of (i) an acryloxy-functional silane having a general formula:
wherein R3 and R4 are the same or different monovalent hydrocarbon radicals, R5 is a divalent hydrocarbon radicals having from 2 to 8 carbon atoms, R6 is hydrogen or mono-valent hydrocarbon radical, b is an integer from 1 to 3, c is an integer from 0 to 2, and d is an integer equaling 4-b-c; or (ii) a glycidoxy-functional silane having a general formula:
wherein R7 and R8 are the same or different monovalent hydrocarbon radicals, R9 is a divalent hydrocarbon radical having from 2 to 8 carbon atoms, e is an integer from 1 to 3, f is an integer from 0 to 2, and g is an integer equaling 4-e-f; or (iii) a mixture of (i) and (ii); and (C) a catalytic amount of an ultraviolet light sensitive photoinitiator or mixture of photoinitiators;
wherein residual solvent has been removed from said coating composition at reduced pressure.

2. A composition as defined in claim 1 wherein said acryloxy-functional silane is selected from the group consisting of:
3-methacryloxypropyltrimethoxysilane 3-acryloxypropyltrimethoxysilane 2-methacryloxyethyltrimethoxysilane 2-acryloxyethyltrimethoxysilane 3-methacryloxypropyltriethoxysilane 3-acryloxypropyltriethoxysilane 2-acryloxyethyltriethoxysilane.

3. A composition as defined in claim 1 wherein said glycidoxy-functional silane is selected from the group consisting of:
3-glycidoxypropyltrimethoxysilane 2-glycidoxyethyltrimethoxysilane 3-glycidoxypropyltriethoxysilane 2-glycidoxyethyltriethoxysilane.

4. A composition as defined in claim 1 wherein said photoinitiator is a radiation sensitive aromatic onium salt having the formula:
(R10 - C6H4)nX+MQ?
wherein X is a radical selected from I, P or S, and M is a metal or metalloid and Q is a halogen radical selected from Cl, F, Br, or I; R10 is hydrogen or a monovalent hydrocarbon radical having 1 to 12 carbon atoms, h is an integer having a value of 4 to 6 inclusive, and n is an integer having a value of 2 or 3.

5. A composition as defined in claim 4 wherein MQ? is selected from SbF6?, AsF6?, BF4?, and PF6?.

6. A composition as defined in claim 4 wherein said photoinitiator is further combined with 0.5 to 5.0 parts of a radical-type photoinitiator.

7. A composition as in claim 6 wherein said radical-type photoinitiator is selected from ethyl benzoin ether, isopropyl benzoin ether, dimethoxyphenylacetophenone and diethoxyacetophenone.

8. A composition as defined in claim 1 which also contains a small amount of polysiloxane polyether copolymer flow control additive.

9. A composition as defined in claim 1 which additionally contains a photo-modifiable compound which is capable of converting to an ultraviolet radiation screening agent upon curing of the coating composition.

10. A composition as defined in claim 9 wherein the photo-modifiable compound has the formula:

where R is hydrogen (H) or methyl (Me).

11. A process for preparing a solventless ultraviolet radiation curable coating composition free of hydroxy acrylates comprising:
(1) combining (A) 100 parts by weight silica in the form of a colloidal dispersion;
(B) 5 to 500 parts by weight of the acid hydrolysis product of (i) an acryloxy-functional silane of the formula:

wherein R3 and R4 are the same or different monovalent hydrocarbon radicals, R5 is a divalent hydrocarbon radical having from 2 to 8 carbon atoms, R6 is hydrogen or a monovalent hydrocarbon radical, b is an integer from 1 to 3, c is an integer from 0 to 2, and d is an integer equal to 4-b-c; or (ii) a glycydoxy-functional silane of the formula:
wherein R7 and R8 are the same or different monovalent hydrocarbon radicals, R9 is a divalent hydrocarbon radical having from 2 to 8 carbon atoms, e is an integer from 1 to 3, f is an integer from O to 2, and g is an integer equal to 4-e-f; or (iii) mixtures of (i) and (ii);
(2) adding a catalytic amount of an ultra-violet light sensitive photoinitiator; and thereafter (3) removing residual solvent at reduced pressure.

12. The process of claim 11 which also contains a small amount of polysiloxane polyether copolymer flow control additive.

13. The process of claim 11 which additionally contains a photo-modifiable compound which is capable of converting to an ultraviolet radiation screening agent upon curing of the coating composition.

14. The process of claim 13 wherein the photo-modifiable compound has the formula:
where R is hydrogen (H) or methyl (Me).

15. The cured product of claim 1.

16. A solid substrate having at least one surface coated with the coating composition of claim 1.

17. An article as defined in claim 16 wherein the solid substrate is comprised of a synthetic organic polymer.

18. An article as defined in claim 16 wherein said solid substrate is a metal.

19. An article as defined in claim 16 wherein said solid substrate is a synthetic organic polymer having a metallized surface.

20. An article as defined in claim 17 wherein said polymer is a transparent polymer.

21. An article as defined in claim 17 wherein said polymer is a polycarbonate.

22. An article as defined in claim 21 wherein said polycarbonate is transparent.

23. An article as defined in claim 21 wherein said polycarbonate is a poly(bisphenol-A carbonate).

24. An article as defined in claim 16 wherein the coating composition has been cured on said surface of said solid substrate by an effective amount of ultra-violet radiation.

25. An article as defined in claim 16 wherein said surface of said solid substrate has been primed with a primer composition prior to being coated.

26. An article as defined in claim 16 wherein said surface of said solid substrate has been primed with a primer composition prior to being coated.

27. An article as defined in claim 25 or 26 wherein said primer composition is comprised of a thermosetting acrylic emulsion.

28. An article as defined in claim 17 wherein said polymer is polymethylmethacrylate.