CA1224182A - Abrasion resistant ultraviolet light curable hard coating compositions - Google Patents
Abrasion resistant ultraviolet light curable hard coating compositionsInfo
- Publication number
- CA1224182A CA1224182A CA000389085A CA389085A CA1224182A CA 1224182 A CA1224182 A CA 1224182A CA 000389085 A CA000389085 A CA 000389085A CA 389085 A CA389085 A CA 389085A CA 1224182 A CA1224182 A CA 1224182A
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- Prior art keywords
- amine
- benzophenone
- coating
- hard coating
- weight
- Prior art date
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Abstract
ABRASION RESISTANT ULTRAVIOLET LIGHT
CURABLE HARD COATING COMPOSITIONS
ABSTRACT OF THE DISCLOSURE
An abrasion resistant hard coating composition which is curable upon exposure to ultraviolet radiation under a noninert atmosphere, such as air, is provided.
The coating composition is comprised of a combination of UV light crosslinkable polyfunctional acrylate monomers and a selected blend of ketone-type and hindered amine-type photoinitiators.
CURABLE HARD COATING COMPOSITIONS
ABSTRACT OF THE DISCLOSURE
An abrasion resistant hard coating composition which is curable upon exposure to ultraviolet radiation under a noninert atmosphere, such as air, is provided.
The coating composition is comprised of a combination of UV light crosslinkable polyfunctional acrylate monomers and a selected blend of ketone-type and hindered amine-type photoinitiators.
Description
60SI-3gl ABRASION RESISTANT ULTRi~VIOLET LIGHT
CUR:i~B:I,E HAR~ COATING CO~?OSITIONS
Field of the Invention This invention reIates to photocurable hard coating compositions,;and articles coated with such compositions. These coatings are comprised of the ; photoreaction products of certain multifunctional acrylate ester monomers or mixtures thereof which are ~' catalyzed with a blend of photoinitiators comprised of photosensitive ketones and certain hindered amines, which are effective for crosslinking the acrylate ester monomers upon exposure'to ultraviolet~radiation. The process of the present invention specifically does not ' require an inert atmosphere such as nitrogen and may in ' 15 fact be carried out in air.
More particularly, this invention relates to an ~' article having a photocured coating thereon which is mar, ``~ abrasion, and solvent resistant, has good adhesion to the substrate, and is compatible with'the substrate i.e., does not adversely affect thè substrate by stress cracking and crazing it, by causing crack propagation into the substrate as a result of brittleness of the coating itse~If,~ and/or - by adversely affecting the' properties of the substrate generally such as, for example, lmpact resistance, elongation, and tensile'strength.
:
' ~-:
~L224~32 Background of the Invention Recently, the substitution of glass glazing with transparent materials which'do not shatter or are more resistant to shattering than 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. ~enses, such as for eye glasses and other optical instruments, as well as glazing for large buildings, also employ shatter-resistant transparent plastics. The lighter weight ofthese plastics in comparison to glass is a further advantage,' especially in the transportation industry where the weight of the vehicle is a major factor in its fuel economy.
While txansparent plastics provide the major ~' advantage Qf being more resistant to shattering and lighter ' than glass, a serious drawback lies in the ease with which '~ these plastics mar and scratch, due to everyday'contact ~'~ with abrasives, such as dust, cleaning equipment and ~` 20 ordinary weathering. Continuous scratching and marring results in impaired~visibility and poor aesthetics, and often requires replacement of 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 Lexan , sold by Gene~al Electric Company.' It is a tough~ material, having high impact strength, high heat deflection temperature,~ good dimensional stability, as well as being se~lf-extinguishing, and is easily fabricated. Acrylics, such as polymethylmethacrylate, are also widel'y used transparent plastics for glazing.
Attempts have been made'to improve~the abrasion-resistance`of transparent pla~stics.~ For example, scratch-resistant coatings formea from mixtures of silica, ~such`as colloidal silica or silica gel, and hydrolyzable silanes `:~
.. , ~ .,.
:.. , :: . ... -: ,:
' ~ ' "`'. `,~
: .: : :: . . . :
.
- ~24J ~;~
in a hydrolysi5 medium, such as alcohol and water, are known. U.S. Patents 3,708,225, Robert D. Misch et al, issued January 2, 1973, 3,986,997, Clark, issued October 19, 1976 and 3,976,497, Clark, issued August 24, 1976.
In Canadian Application Serial No. 339,539 , November 9, 1979, coating compositions havin~ improved resistance to moisture`and humidity and ultraviolet light are disclosed. It was discovered therein that, in direct contrast to the teachings of U.S. Patent 3,986,997 compositions having a basic pH, i.e., 7.1-7.8, do not immediately gel but in fact provide excellent abrasion-resistant coatings on solid substrates.
The present~ invention offers a significant ~; advantaye over many of the heretofore known coating compositions in that it does not require heat in order to initiate the cure reaction. The radiation cure system of ~` the present invention expends considerably less thermal energy than conventional heat cure systems.
In copending Canadian Application Serial No.
376,679, May 1, 1981, the present applicant has disclosed a radiation curable hardcoating composition which requires the use of the acid hydrolysis product of an alkoxy functional silane. In another copending application, Serial No. 380,250, June 19, lg81, the present applicant has provided a different radiation curable hardcoating composition which requires the combination of colloidal silica, acryloxy or glycidoxy functional silanes and non-silyl acrylates. Applicant's present invention, however, provides highIy abrasion resistant coatings which require neither alkoxy functional silanes of Serial No. 376,679 nor the acryloxy or glycidoxy functional silanes of Serial No. 380,250.
In fact, the coating compositions of the present invention are specific improvements over the coatings and articles disclosed in U.S. Patent No. 4,13&,465, Moore et `:
`"' ~, ' .,' , , ' :;, ,. ~
: ~ :, , ,:
, ~zg~
al, April 15, 1~80. The Moore et al disclosure teaches that certain very useful coatings and coated articles can be provided through the photoreaction of certain poly-functional acrylate monomers and resorcinol monobenzoate.
The Moore et al coatings use any of several well known ;; W radiation photosensitizers including ketones such as benzophenone. The Moore et al disclosure, however, failed to recognize that the improved coatings of the present invention could be provided by combining the ketone-type photoinitiator with a hindered amine-type compound whereupon the photosensitized acrylate coating composition could be cured without the necessity of using resorcinol monobenzoate and without the necessity of an inert atmosphere (both of which are required by the Moore et al disclosure~, in order to provide suitable and ` sometimes improved hard coatings. The savings provided by the use of a non-inert atmosphere such as air can be substantial, and these savings can be provided by the -~ present invention without derogating from the quality of the hard coating composition or coated product.
Since ultraviolet light is one of the most widely ; used types of radiation because of its relatively low cost, ease of maintenance, and low potential harzard to industrial users, rapid photo-induced polymerizations utilizing UV light rather than thermal energy for the curing of hard coatings offer several other significant advantages. First, faster curing coatings offer substantial economic benefits. Furthermore, heat sensitive materials can be safely coated and cured with UV light without the use of thermal energy which could damage the substrate. Additionally, the essentially solvent free media reduce the necessity for expensive ; and time consuming pollution abatement procedures.
Thus, the advantages provided by the 35 materials of the present invention are particularly ~ c~~
for a number of purposes. For e~ample, ., ".. ...
., ' -'' :.''' -' .~ ": ' , ' ' ... .. .
~2Z4~2 polycarbonates are commercially important materials possessing exceIlent physical and chemical properties which are useful in a wide range of applications from non-opaque impact resistant sheets to shaped articles.
Generally, however, polycarbonates have rathex low scratch resistance and are somewhat susceptible to attac~ by many common solvents and chemicals.
; Previous efforts to overcome this low scratch resistance and susceptibility to attack by solvents have included lamination procedures and applications onto the polycarbonate of a surface coating. Many of these prior ; art remedial efforts have been unsuccessful due to the incompatibility of the laminae and coating materials with the polycarbonate substrate. This incompatibility has resulted in stress cracking and crazing of the polycarbonate, crack propagation into the polycarbonate as a result of the brittleness of the coating, and a reduction of the advantageous properties of the polycarbonate such as, for example, impact resistance, tensile strength, non-opacity and elongation.
The prior art coatings for polycarbonates have included organopolysiloxanes, U.S. Patent No. 3,707,397, Gagnon, issued ~ecember 26, 1972; polyester-melamines or acrylic-melamines, U.S. Patent No. 3,343,390, Hudson et al, issued October 22, 1974; and allyl resins, U.S.
Patent No. 2,332,461. These types of prior art coatings are generally applied from solutions of inert solvents and are cured to ~inal properties by baking at elevated - temperatures. The disadvantages of such systems are obvious. The heat curing requires a supply of thermal energy thereby adding to the cost of the system. Further, the thermal curing step is somewhat limited by the hea~
distortion temperature of the polycarbonate which is to be coated. Thus, in coating of polycarbonates, sheets of 30 mils and Iess generally cannot be coated and cured ~, : :: . :
~ZZ4~82 economically because of excessive warpage of the sheets during the thermal curing process.
U.S. Patent No. 3,968,305, Oshima et al, issued ~uly 6, 1976, describes a synthetic shaped article having a mar-resistant polymer surface layer inegrated with the polymer surface body, said polymer surface layer consisting essentially of, in polymerized form, (a) 20 to 100 weight percent of a compound having a total of at least three acryloxy and/or methacryloxy groups linked with a straight chain aliphatic hydrocarbon residue having not more than 20 caxbon atoms, and (b) 0 to 80 weight percent of at least one copolymerizable mono- or diethylenically unsaturated compound. This type of a surface layer suffers from the fact that it generally has poor durability of adhesion after prolonged exposure to weathering.
U.S. Patent`No. 3,968,309, Matsuo et al, issued July 6, 1976, describes a molded article of plastic having on its surface a cured film of a coating material comprising at least 30% by weight of at least one polyfunctional compound selected from the group consisting of polymeth-acryloxy compounds having a molecular weight of 250 to 800 and containing at least three methacryloyloxy groups in the molecule and polyacryloyloxy compounds having a molecular weight of 250 to 800 and containing at least three acryloyloxy groups in the molecule. This patent, however, also teaches that this coating must contain from 0.01 to 5% by weight of a fluorine-containing surfactant in order for the coated article to be acceptable. This patent teaches that when the coating material contains less than 0.01% by weight of the fluorine-containing surfactant, it is impossible to obtain a coated article having the requisite degree`of surface hardness, surface smoothness, abrasion resistance and optical clarity. If the coating material contains more than 5~ by weight of said fluorine-containing surfa~tant, the adhesion between : `
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.
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-` ~2;~:4~2 a cured film of the coating material and a molded substrate of plastic is unsatisfactory.
It has now been found that a coating composition containing certain specific polyfunctional aGrylic monomers in combination with a blend of ketone and hindered amine photoinitiators providés excellent and durable UV cured coatings, especially for high strength plastic substrates such as polycarbonate, polyester, polymethylmethacrylate, and other polyacrylates, as well as polyamides, nylon and metalized plastic surfaces. These materials may be in films or sheets as well as in the form of molded parts. Thus, the present invention provides certain acrylate ester monomer based UV-cured coatings which adhere tenaciously and durably to the substrate, are compatible with the substrate, are mar, abrasion and solvent resistant, and maintain properties after prolon~ed exposure to weathering.
It is therefore an object of the present invention to provide ultraviolet light curable coating compositions ` 20 providing improved mar and abrasion resistance which are curable under a non-inert atmosphere such as air.
It is another abject to provide a UV curable coating comprising the photoreaction products of certain polyfunctional acrylate monomers and a bIend of ketone-type and hindered amine-type photoinitiators.
~` It is anothe`r object to provide a process for providing abrasion resistant ultraviolet light curable coating compositions which are curable on rigid and flexible substrates, and which do not require an inert atmosphere for proper curing thereon.
It is still another object to provide articles of manufacture which are highIy mar and abrasion resistant by virtue of ha`ving been coated with the coatings of the present invention which have been cur~d thereon.
,: ;.
.
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~Z4~512 Summary of the Invention The present inven-tion provides an abrasion resistant, durably adhered, ultraviolet light curable hardcoating composition which is curable in a non-inert -~ 5 atmosphere, and which comprises:
(A) at least one ultraviolet light curable (i.e. cross-linkable) polyfunctional acrylate monomer represented by the general formula (H2C=CR' -COO) n~~R
lQ
wherein n is an integer having a value of from 1 to 4, and R is selected from the group consisting of n valent aliphatic hydrocarbon residue, n valent aliphatic hydrocarbon residue containing at least one ether linkage, and n valent substituted hydrocarbon residue of either type, and R' is hydrogen or a lower alkyl radical s`uch as methyl.
~ . ~ cor~Pos; tlor~, The coating aompoistion is completed by adding to ingredient (A) a blend of photoinitiators which have been discovered e'ffective for crosslinking (A) to form the hard coatings of the present invention, upon exposure to ultra-violet radiation and without the necessity of an inert (e.g. N2) blanketing atmosphere.
Description of the Invention In accordance with the present invention, there may be provided a non-opaque, more specifically, a transparent, article having deposited on thè surface thèreof an adherent, mar, abrasion and chemical resistant non-opaque coating, said coating containing the photoreaction 3Q products of at least one W curabIe polyfunctional acrylate monomer, and a blend of ketone and amine type ^' photoinitiators as will be described beIow. The coating is obtained through the UV cure of a UV curable'coating '~ composition comprised of (i) at least one'UV curable polyfunctional acrylate monomer, and (ii) the seIected ,~ .
.~;. :
!32 photoinitiator blend, under a non-inert atmosphere. An anti-weathering agent such as resorcinol monobenzoate, resorcinol dibenzoate, methyl rescorcinol monobenzoate, and methyl resorcinol dibenzoate, and may be included if optionally desired.
To exemplify the practice of this invention, any of the aromatic polycarbonates can be employed. These are homopolymers and copolymers and mixtures thereof that are prepared by reactin~ a dihydric phenol with a carbonate precursor. Typical of some of the dihydric phenols that may be employed in the practice of this invention are bisphenol-A (2r2-bis(4-hydroxyphenyl)propane), bis(4-hydroxy-phenyl)methane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 3,3-bis(4-hydroxyphenyl~pentane, 2,2-bis(3,5-dichloro-4-` 15 hydroxyphenyl~propane, 2,2-bis(4,3,5-dibromo-4-hydroxyphenyl)-propane, and bis(3-chloro-4-hydroxyphenyl) methane. Other dihydric phenols of the bisphenol type are also available and are disclosed in U.S. Patent Nos.2,999,835, issued September 12, 1961 to Goldberg; 3,02~,365, issued April 3, 20 1962 to Schnell et al; and 3,334,154, issued August 1, 1967 to Kim.
It is, of course, possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with a glycol or with hydroxy or acid terminated polyester, or with a dibasic acid in the event a carbonate copolymer or interpolymer rather than a homopolymer is desired fox use in the preparation of the aromatic carbonate polymers of this invention. Also employed in the practice of this invention may be blends of any of the above materials to provide the aromatic carbonate polymer.
To carbonate precursor may be either a carbonyl halide, a carbonate ester or a haloformate. The -~arbonyl halides which can be employed herein are carbonyl bromide, carbonyl chloride and mixtures thereof. Typical `~ 35 of the carbonate esters which may be employed herein are diphenyl carbonate, di-(halophenyl) carbonates such as di-(chlorophenyl) carbonate, di-(bromophenyl) carbonate, .
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di-(trichlorophenyl) carbonate, di-(tribromophenyl) carbonate, etc., di-~alkylphenyl) carbonate such as di(tolyl) carbonate, etc., di-(naphthyl) carbonate, di-(chIoronaphthyl) carbonate, phenyl tolyl carbonate, chIorophenyl chIoronaphthyl carbonate, etc., or mixtures thereof. The haloformates suitable for ~ use herein include bis-haloformates of dihydric phenols - ~bischloroformates of hydroquinone, etc.) or glycols (bishaloformates of ethylene glycol, neopentyl glycol, polyethylene glycol, etc.). While other carbonate precursors will occur to those skilled in the art, carbonyl chloride, also known as phosgene, is preferred.
Also included are the polymeric derivatives of a dihydric phenol, a dicarboxylic acid and carbonic acid.
These are disclosed in U.S. Patent No. 3,169,121, Goldberg, issued February 9, 1965.
The aromatic carbonate polymers of this invention may be prepared by employing a molecular weight regulator, an acid acceptor and a catalyst. The molecular weight regulators which`can be employed in carrying out the process of this invention include monohydric phenols such as phenol, chroman-I, para-tertiarybutyl-phenol, para-bromophenol, primary and secondary amines, etc.
Preferably phenol is employed as the molecular weight regulator.
A suitable acid acceptor may be either an organic or an inorganic acid acceptor. A suitable organic acid acceptor is a tertiary amine and includes such materials as pydridine, triethylamine, dimethylaniline, tributylamine, etc. The inorganic acid acceptor may be one which can be either a hydroxide, a carbonate, a bicarbonate, or a ; phosphate of an alkaki or alkaline earth metal.
The catalysts which are employed here can be any of the`suitable catalysts that aid the polymerization of bisphenol-A with`phosgene.` SuitabIe catalysts include tertiary amines such as, for example, triethylamine, :, .
.,.. :. . : :
":`: "'', : .
.. : .: . .
~:2~2 ÇOSI-391 tripropylamine, N,N-dimethylaniline, quaternary ammonium compounds such as, for example, tetraethylammonium bromide, cetyl triethyl ammonium bromide, tetra-n-heptyl-ammonium iodide, tetra-n-propyl ammonium bromide, tetramethyl ammonium chIoride, tetramethyl-ammonium hydroxide, tetra-n-butyl-ammonium iodide, benzyltrime-` thylammonium chloride and quaternary phosphonium compounds such as, for example, n-butyltriphenyl phosphonium bromide and methyltriphenyl phosphonium bromide.
Also included therein are branched polycarbonates wherein a polyfunctional aromatic compound is reacted with the dihydric phenol and carbonate precursor to provide a thermplastic randomly branched polycarbonate.
These polyfunctional aromatic compounds contain at least three functional groups which are carboxyl, carboxylic anhydride, or haloformyl groups or mixtures thereof. Examples of these polyfunctional aromatic compounds which may be employed in the practice of this invention include: trimellitic anhydride, trimellitic acid, trimellityl trichloride, ~-chloroformyl phthalic anhydride, pyromellitic acid, pyromellitic dianhydride, . mellitic acid, mellitic anhydride, trimesic acid, ~; ~ b,~ ,p/~ "~r~c~l, b~.Yy/~c '~,' -be ~ e ~ _ ~ acld, benzophenonetetracarboxyllc anhydride and the like. The preferred polyfunctional aromatic compounds are trimellitic anhydride or trimellitic acid, or their haloformyl deri~atives.
Also included herein are blends of a linear polycarbonate and a branched polycarbonate.
It is to be understood that the utility of the coating composition of the present inventio~ is not limited to the polycarbonates described abo~e. There are numerous other classes of substrates which may be suitably rendered mar and abrasion resistant by the coatings and processes disclosed herein. Among these other substrates are such sheet, film and molded substrates .. : .
~Z2~3Z
as polyester and polymethylmethacrylate and other high - strength films such as polyacrylates, polyamides, nylon and plastic surfaces which have been metalized by such techniques as sputtering, electroplating and vapor deposition. Metal surfaces such as aluminum may also be ~ coated.
:~ The polyfunctional acrylate ester monomers of the present invention are represented by the general formula O
( I ) 2 C ~C - C - - ~ --- R
R J n wherein n is an integer from l to 8, preferably from l to 6, and more preferably from l to 4; and R is a n functional hydrocarbon residue, a n functional substituted hydrocarbon residue, a n functional hydrocarbon residue containing at least one ether linkage, and a n functional substituted hydrocarbon residue containing at least one ether linkage, and R' is hydrogen or a lower alkyl radical such as methyl.
Preferred n functional hydrocarbon residues are the n functional aliphatic, preferably saturated aliphatic, hydrocarbon residues containing from l to about 20 carbon atoms and the n functional aromatic hydrocarbon residues containing from 6 to about lO carbon atoms.
Preferred n functional hydrocarbon residues : 25 containing at least one ether linkage are the n functional aliphatic hydrocarbon residues, preferably saturated : aliphatic hydrocarbon residues, containing from l to about 5 ether linkages and from 2 to about 20 carbon atoms.
~:~ 30 Preferred n functional substituted hydrocarbon :~ residues are the n functional aliphatic hydrocarbon residues, preferably the saturated aliphatic hydrocarbon .~
:.
:"
~' ~' `; ` `' ~ '.'.. ` : ' " ' ' " ' .~ . :
: ~ ,,:; " , Z
60SI-3gl residues, containin~ from 1 to about 20 carbon atoms, ; and the n functional aromatic hydrocarbon residues containing from 6 to about 10 carbon atoms which contain substituent groups such as the halogens, i.e., fluorine, chIorine, bromine and iodine, hydroxyl, --COOH, and --COOR' groups wherein R~ represents alkyl groups containing from 1 to about 6 carbon atoms.
Preferred n functional substituted hydrocarbon residues containing at least one ether linkage are the n functional aliphatic, preferably saturated aliphatic, hydrocarbon residues containing from 2 to about 20 carbon atoms and from 1 to about 5 ether linkages which contain substituent groups such as the halogen hydroxyl, --COOH, and --COOR' groups wherein R' is as defined above.
It is to be understood that where substituent groups are present, they should be such that they do not unduly hinder or interfere with the photocure of the polyfunctional acrylic monomers.
The more preferred polyfunctional acrylic monomers are those represented by formula I wherein R is selected from the group consisting of an n functional saturated aliphatic hydrocarbon residue containing from 1 to about 20 carbon atoms, a hydroxyl substituted n fuhctional saturated aliphatic hydrocarbon residue containing from 1 to about 20 carbon atoms, an n functional saturated aliphatic hydrocarbon residue containing from about 2 to about 20 carbon atoms and from about 1 to about 5 ether linkages, and a hydroxyl substituted n functional saturated aliphatic hydrocarbon residue containing from 2 to about 20 carbo~ atoms and from 1 to about 5 ethe`r linkages.
The preferred polyfunctional acrylate ester monomers are those wherein R is an n funct~ional saturated aliphatic hydrocarbon, ether, or polyether radical, with those monomers wherein ~ is an n valent saturated . . .
, ' . ,:, --: ::.
:,.. .. . .
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aliphatic hydrocarbon radical being more preferred.
More particularly, the difunctional acrylic monomers, or diacrylates, are represented by formula I
wherein n is 2; the trifunctional acrylic monomers, or triacrylates, are represented by formula I wherein n is 3; and the tetra-functional acrylic monomers, or : tetraacrylates, are represented by formula I wherein n is 4. Illustrative of suitable polyfunctional acrylate ester ~onomers of formula I are those listed below in TABLE I.
TABLE I
CUR:i~B:I,E HAR~ COATING CO~?OSITIONS
Field of the Invention This invention reIates to photocurable hard coating compositions,;and articles coated with such compositions. These coatings are comprised of the ; photoreaction products of certain multifunctional acrylate ester monomers or mixtures thereof which are ~' catalyzed with a blend of photoinitiators comprised of photosensitive ketones and certain hindered amines, which are effective for crosslinking the acrylate ester monomers upon exposure'to ultraviolet~radiation. The process of the present invention specifically does not ' require an inert atmosphere such as nitrogen and may in ' 15 fact be carried out in air.
More particularly, this invention relates to an ~' article having a photocured coating thereon which is mar, ``~ abrasion, and solvent resistant, has good adhesion to the substrate, and is compatible with'the substrate i.e., does not adversely affect thè substrate by stress cracking and crazing it, by causing crack propagation into the substrate as a result of brittleness of the coating itse~If,~ and/or - by adversely affecting the' properties of the substrate generally such as, for example, lmpact resistance, elongation, and tensile'strength.
:
' ~-:
~L224~32 Background of the Invention Recently, the substitution of glass glazing with transparent materials which'do not shatter or are more resistant to shattering than 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. ~enses, such as for eye glasses and other optical instruments, as well as glazing for large buildings, also employ shatter-resistant transparent plastics. The lighter weight ofthese plastics in comparison to glass is a further advantage,' especially in the transportation industry where the weight of the vehicle is a major factor in its fuel economy.
While txansparent plastics provide the major ~' advantage Qf being more resistant to shattering and lighter ' than glass, a serious drawback lies in the ease with which '~ these plastics mar and scratch, due to everyday'contact ~'~ with abrasives, such as dust, cleaning equipment and ~` 20 ordinary weathering. Continuous scratching and marring results in impaired~visibility and poor aesthetics, and often requires replacement of 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 Lexan , sold by Gene~al Electric Company.' It is a tough~ material, having high impact strength, high heat deflection temperature,~ good dimensional stability, as well as being se~lf-extinguishing, and is easily fabricated. Acrylics, such as polymethylmethacrylate, are also widel'y used transparent plastics for glazing.
Attempts have been made'to improve~the abrasion-resistance`of transparent pla~stics.~ For example, scratch-resistant coatings formea from mixtures of silica, ~such`as colloidal silica or silica gel, and hydrolyzable silanes `:~
.. , ~ .,.
:.. , :: . ... -: ,:
' ~ ' "`'. `,~
: .: : :: . . . :
.
- ~24J ~;~
in a hydrolysi5 medium, such as alcohol and water, are known. U.S. Patents 3,708,225, Robert D. Misch et al, issued January 2, 1973, 3,986,997, Clark, issued October 19, 1976 and 3,976,497, Clark, issued August 24, 1976.
In Canadian Application Serial No. 339,539 , November 9, 1979, coating compositions havin~ improved resistance to moisture`and humidity and ultraviolet light are disclosed. It was discovered therein that, in direct contrast to the teachings of U.S. Patent 3,986,997 compositions having a basic pH, i.e., 7.1-7.8, do not immediately gel but in fact provide excellent abrasion-resistant coatings on solid substrates.
The present~ invention offers a significant ~; advantaye over many of the heretofore known coating compositions in that it does not require heat in order to initiate the cure reaction. The radiation cure system of ~` the present invention expends considerably less thermal energy than conventional heat cure systems.
In copending Canadian Application Serial No.
376,679, May 1, 1981, the present applicant has disclosed a radiation curable hardcoating composition which requires the use of the acid hydrolysis product of an alkoxy functional silane. In another copending application, Serial No. 380,250, June 19, lg81, the present applicant has provided a different radiation curable hardcoating composition which requires the combination of colloidal silica, acryloxy or glycidoxy functional silanes and non-silyl acrylates. Applicant's present invention, however, provides highIy abrasion resistant coatings which require neither alkoxy functional silanes of Serial No. 376,679 nor the acryloxy or glycidoxy functional silanes of Serial No. 380,250.
In fact, the coating compositions of the present invention are specific improvements over the coatings and articles disclosed in U.S. Patent No. 4,13&,465, Moore et `:
`"' ~, ' .,' , , ' :;, ,. ~
: ~ :, , ,:
, ~zg~
al, April 15, 1~80. The Moore et al disclosure teaches that certain very useful coatings and coated articles can be provided through the photoreaction of certain poly-functional acrylate monomers and resorcinol monobenzoate.
The Moore et al coatings use any of several well known ;; W radiation photosensitizers including ketones such as benzophenone. The Moore et al disclosure, however, failed to recognize that the improved coatings of the present invention could be provided by combining the ketone-type photoinitiator with a hindered amine-type compound whereupon the photosensitized acrylate coating composition could be cured without the necessity of using resorcinol monobenzoate and without the necessity of an inert atmosphere (both of which are required by the Moore et al disclosure~, in order to provide suitable and ` sometimes improved hard coatings. The savings provided by the use of a non-inert atmosphere such as air can be substantial, and these savings can be provided by the -~ present invention without derogating from the quality of the hard coating composition or coated product.
Since ultraviolet light is one of the most widely ; used types of radiation because of its relatively low cost, ease of maintenance, and low potential harzard to industrial users, rapid photo-induced polymerizations utilizing UV light rather than thermal energy for the curing of hard coatings offer several other significant advantages. First, faster curing coatings offer substantial economic benefits. Furthermore, heat sensitive materials can be safely coated and cured with UV light without the use of thermal energy which could damage the substrate. Additionally, the essentially solvent free media reduce the necessity for expensive ; and time consuming pollution abatement procedures.
Thus, the advantages provided by the 35 materials of the present invention are particularly ~ c~~
for a number of purposes. For e~ample, ., ".. ...
., ' -'' :.''' -' .~ ": ' , ' ' ... .. .
~2Z4~2 polycarbonates are commercially important materials possessing exceIlent physical and chemical properties which are useful in a wide range of applications from non-opaque impact resistant sheets to shaped articles.
Generally, however, polycarbonates have rathex low scratch resistance and are somewhat susceptible to attac~ by many common solvents and chemicals.
; Previous efforts to overcome this low scratch resistance and susceptibility to attack by solvents have included lamination procedures and applications onto the polycarbonate of a surface coating. Many of these prior ; art remedial efforts have been unsuccessful due to the incompatibility of the laminae and coating materials with the polycarbonate substrate. This incompatibility has resulted in stress cracking and crazing of the polycarbonate, crack propagation into the polycarbonate as a result of the brittleness of the coating, and a reduction of the advantageous properties of the polycarbonate such as, for example, impact resistance, tensile strength, non-opacity and elongation.
The prior art coatings for polycarbonates have included organopolysiloxanes, U.S. Patent No. 3,707,397, Gagnon, issued ~ecember 26, 1972; polyester-melamines or acrylic-melamines, U.S. Patent No. 3,343,390, Hudson et al, issued October 22, 1974; and allyl resins, U.S.
Patent No. 2,332,461. These types of prior art coatings are generally applied from solutions of inert solvents and are cured to ~inal properties by baking at elevated - temperatures. The disadvantages of such systems are obvious. The heat curing requires a supply of thermal energy thereby adding to the cost of the system. Further, the thermal curing step is somewhat limited by the hea~
distortion temperature of the polycarbonate which is to be coated. Thus, in coating of polycarbonates, sheets of 30 mils and Iess generally cannot be coated and cured ~, : :: . :
~ZZ4~82 economically because of excessive warpage of the sheets during the thermal curing process.
U.S. Patent No. 3,968,305, Oshima et al, issued ~uly 6, 1976, describes a synthetic shaped article having a mar-resistant polymer surface layer inegrated with the polymer surface body, said polymer surface layer consisting essentially of, in polymerized form, (a) 20 to 100 weight percent of a compound having a total of at least three acryloxy and/or methacryloxy groups linked with a straight chain aliphatic hydrocarbon residue having not more than 20 caxbon atoms, and (b) 0 to 80 weight percent of at least one copolymerizable mono- or diethylenically unsaturated compound. This type of a surface layer suffers from the fact that it generally has poor durability of adhesion after prolonged exposure to weathering.
U.S. Patent`No. 3,968,309, Matsuo et al, issued July 6, 1976, describes a molded article of plastic having on its surface a cured film of a coating material comprising at least 30% by weight of at least one polyfunctional compound selected from the group consisting of polymeth-acryloxy compounds having a molecular weight of 250 to 800 and containing at least three methacryloyloxy groups in the molecule and polyacryloyloxy compounds having a molecular weight of 250 to 800 and containing at least three acryloyloxy groups in the molecule. This patent, however, also teaches that this coating must contain from 0.01 to 5% by weight of a fluorine-containing surfactant in order for the coated article to be acceptable. This patent teaches that when the coating material contains less than 0.01% by weight of the fluorine-containing surfactant, it is impossible to obtain a coated article having the requisite degree`of surface hardness, surface smoothness, abrasion resistance and optical clarity. If the coating material contains more than 5~ by weight of said fluorine-containing surfa~tant, the adhesion between : `
.. . ~:. . .
.
',:~
-` ~2;~:4~2 a cured film of the coating material and a molded substrate of plastic is unsatisfactory.
It has now been found that a coating composition containing certain specific polyfunctional aGrylic monomers in combination with a blend of ketone and hindered amine photoinitiators providés excellent and durable UV cured coatings, especially for high strength plastic substrates such as polycarbonate, polyester, polymethylmethacrylate, and other polyacrylates, as well as polyamides, nylon and metalized plastic surfaces. These materials may be in films or sheets as well as in the form of molded parts. Thus, the present invention provides certain acrylate ester monomer based UV-cured coatings which adhere tenaciously and durably to the substrate, are compatible with the substrate, are mar, abrasion and solvent resistant, and maintain properties after prolon~ed exposure to weathering.
It is therefore an object of the present invention to provide ultraviolet light curable coating compositions ` 20 providing improved mar and abrasion resistance which are curable under a non-inert atmosphere such as air.
It is another abject to provide a UV curable coating comprising the photoreaction products of certain polyfunctional acrylate monomers and a bIend of ketone-type and hindered amine-type photoinitiators.
~` It is anothe`r object to provide a process for providing abrasion resistant ultraviolet light curable coating compositions which are curable on rigid and flexible substrates, and which do not require an inert atmosphere for proper curing thereon.
It is still another object to provide articles of manufacture which are highIy mar and abrasion resistant by virtue of ha`ving been coated with the coatings of the present invention which have been cur~d thereon.
,: ;.
.
.. : , .
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~Z4~512 Summary of the Invention The present inven-tion provides an abrasion resistant, durably adhered, ultraviolet light curable hardcoating composition which is curable in a non-inert -~ 5 atmosphere, and which comprises:
(A) at least one ultraviolet light curable (i.e. cross-linkable) polyfunctional acrylate monomer represented by the general formula (H2C=CR' -COO) n~~R
lQ
wherein n is an integer having a value of from 1 to 4, and R is selected from the group consisting of n valent aliphatic hydrocarbon residue, n valent aliphatic hydrocarbon residue containing at least one ether linkage, and n valent substituted hydrocarbon residue of either type, and R' is hydrogen or a lower alkyl radical s`uch as methyl.
~ . ~ cor~Pos; tlor~, The coating aompoistion is completed by adding to ingredient (A) a blend of photoinitiators which have been discovered e'ffective for crosslinking (A) to form the hard coatings of the present invention, upon exposure to ultra-violet radiation and without the necessity of an inert (e.g. N2) blanketing atmosphere.
Description of the Invention In accordance with the present invention, there may be provided a non-opaque, more specifically, a transparent, article having deposited on thè surface thèreof an adherent, mar, abrasion and chemical resistant non-opaque coating, said coating containing the photoreaction 3Q products of at least one W curabIe polyfunctional acrylate monomer, and a blend of ketone and amine type ^' photoinitiators as will be described beIow. The coating is obtained through the UV cure of a UV curable'coating '~ composition comprised of (i) at least one'UV curable polyfunctional acrylate monomer, and (ii) the seIected ,~ .
.~;. :
!32 photoinitiator blend, under a non-inert atmosphere. An anti-weathering agent such as resorcinol monobenzoate, resorcinol dibenzoate, methyl rescorcinol monobenzoate, and methyl resorcinol dibenzoate, and may be included if optionally desired.
To exemplify the practice of this invention, any of the aromatic polycarbonates can be employed. These are homopolymers and copolymers and mixtures thereof that are prepared by reactin~ a dihydric phenol with a carbonate precursor. Typical of some of the dihydric phenols that may be employed in the practice of this invention are bisphenol-A (2r2-bis(4-hydroxyphenyl)propane), bis(4-hydroxy-phenyl)methane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 3,3-bis(4-hydroxyphenyl~pentane, 2,2-bis(3,5-dichloro-4-` 15 hydroxyphenyl~propane, 2,2-bis(4,3,5-dibromo-4-hydroxyphenyl)-propane, and bis(3-chloro-4-hydroxyphenyl) methane. Other dihydric phenols of the bisphenol type are also available and are disclosed in U.S. Patent Nos.2,999,835, issued September 12, 1961 to Goldberg; 3,02~,365, issued April 3, 20 1962 to Schnell et al; and 3,334,154, issued August 1, 1967 to Kim.
It is, of course, possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with a glycol or with hydroxy or acid terminated polyester, or with a dibasic acid in the event a carbonate copolymer or interpolymer rather than a homopolymer is desired fox use in the preparation of the aromatic carbonate polymers of this invention. Also employed in the practice of this invention may be blends of any of the above materials to provide the aromatic carbonate polymer.
To carbonate precursor may be either a carbonyl halide, a carbonate ester or a haloformate. The -~arbonyl halides which can be employed herein are carbonyl bromide, carbonyl chloride and mixtures thereof. Typical `~ 35 of the carbonate esters which may be employed herein are diphenyl carbonate, di-(halophenyl) carbonates such as di-(chlorophenyl) carbonate, di-(bromophenyl) carbonate, .
'~
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, . .
lZ24~8Z
di-(trichlorophenyl) carbonate, di-(tribromophenyl) carbonate, etc., di-~alkylphenyl) carbonate such as di(tolyl) carbonate, etc., di-(naphthyl) carbonate, di-(chIoronaphthyl) carbonate, phenyl tolyl carbonate, chIorophenyl chIoronaphthyl carbonate, etc., or mixtures thereof. The haloformates suitable for ~ use herein include bis-haloformates of dihydric phenols - ~bischloroformates of hydroquinone, etc.) or glycols (bishaloformates of ethylene glycol, neopentyl glycol, polyethylene glycol, etc.). While other carbonate precursors will occur to those skilled in the art, carbonyl chloride, also known as phosgene, is preferred.
Also included are the polymeric derivatives of a dihydric phenol, a dicarboxylic acid and carbonic acid.
These are disclosed in U.S. Patent No. 3,169,121, Goldberg, issued February 9, 1965.
The aromatic carbonate polymers of this invention may be prepared by employing a molecular weight regulator, an acid acceptor and a catalyst. The molecular weight regulators which`can be employed in carrying out the process of this invention include monohydric phenols such as phenol, chroman-I, para-tertiarybutyl-phenol, para-bromophenol, primary and secondary amines, etc.
Preferably phenol is employed as the molecular weight regulator.
A suitable acid acceptor may be either an organic or an inorganic acid acceptor. A suitable organic acid acceptor is a tertiary amine and includes such materials as pydridine, triethylamine, dimethylaniline, tributylamine, etc. The inorganic acid acceptor may be one which can be either a hydroxide, a carbonate, a bicarbonate, or a ; phosphate of an alkaki or alkaline earth metal.
The catalysts which are employed here can be any of the`suitable catalysts that aid the polymerization of bisphenol-A with`phosgene.` SuitabIe catalysts include tertiary amines such as, for example, triethylamine, :, .
.,.. :. . : :
":`: "'', : .
.. : .: . .
~:2~2 ÇOSI-391 tripropylamine, N,N-dimethylaniline, quaternary ammonium compounds such as, for example, tetraethylammonium bromide, cetyl triethyl ammonium bromide, tetra-n-heptyl-ammonium iodide, tetra-n-propyl ammonium bromide, tetramethyl ammonium chIoride, tetramethyl-ammonium hydroxide, tetra-n-butyl-ammonium iodide, benzyltrime-` thylammonium chloride and quaternary phosphonium compounds such as, for example, n-butyltriphenyl phosphonium bromide and methyltriphenyl phosphonium bromide.
Also included therein are branched polycarbonates wherein a polyfunctional aromatic compound is reacted with the dihydric phenol and carbonate precursor to provide a thermplastic randomly branched polycarbonate.
These polyfunctional aromatic compounds contain at least three functional groups which are carboxyl, carboxylic anhydride, or haloformyl groups or mixtures thereof. Examples of these polyfunctional aromatic compounds which may be employed in the practice of this invention include: trimellitic anhydride, trimellitic acid, trimellityl trichloride, ~-chloroformyl phthalic anhydride, pyromellitic acid, pyromellitic dianhydride, . mellitic acid, mellitic anhydride, trimesic acid, ~; ~ b,~ ,p/~ "~r~c~l, b~.Yy/~c '~,' -be ~ e ~ _ ~ acld, benzophenonetetracarboxyllc anhydride and the like. The preferred polyfunctional aromatic compounds are trimellitic anhydride or trimellitic acid, or their haloformyl deri~atives.
Also included herein are blends of a linear polycarbonate and a branched polycarbonate.
It is to be understood that the utility of the coating composition of the present inventio~ is not limited to the polycarbonates described abo~e. There are numerous other classes of substrates which may be suitably rendered mar and abrasion resistant by the coatings and processes disclosed herein. Among these other substrates are such sheet, film and molded substrates .. : .
~Z2~3Z
as polyester and polymethylmethacrylate and other high - strength films such as polyacrylates, polyamides, nylon and plastic surfaces which have been metalized by such techniques as sputtering, electroplating and vapor deposition. Metal surfaces such as aluminum may also be ~ coated.
:~ The polyfunctional acrylate ester monomers of the present invention are represented by the general formula O
( I ) 2 C ~C - C - - ~ --- R
R J n wherein n is an integer from l to 8, preferably from l to 6, and more preferably from l to 4; and R is a n functional hydrocarbon residue, a n functional substituted hydrocarbon residue, a n functional hydrocarbon residue containing at least one ether linkage, and a n functional substituted hydrocarbon residue containing at least one ether linkage, and R' is hydrogen or a lower alkyl radical such as methyl.
Preferred n functional hydrocarbon residues are the n functional aliphatic, preferably saturated aliphatic, hydrocarbon residues containing from l to about 20 carbon atoms and the n functional aromatic hydrocarbon residues containing from 6 to about lO carbon atoms.
Preferred n functional hydrocarbon residues : 25 containing at least one ether linkage are the n functional aliphatic hydrocarbon residues, preferably saturated : aliphatic hydrocarbon residues, containing from l to about 5 ether linkages and from 2 to about 20 carbon atoms.
~:~ 30 Preferred n functional substituted hydrocarbon :~ residues are the n functional aliphatic hydrocarbon residues, preferably the saturated aliphatic hydrocarbon .~
:.
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60SI-3gl residues, containin~ from 1 to about 20 carbon atoms, ; and the n functional aromatic hydrocarbon residues containing from 6 to about 10 carbon atoms which contain substituent groups such as the halogens, i.e., fluorine, chIorine, bromine and iodine, hydroxyl, --COOH, and --COOR' groups wherein R~ represents alkyl groups containing from 1 to about 6 carbon atoms.
Preferred n functional substituted hydrocarbon residues containing at least one ether linkage are the n functional aliphatic, preferably saturated aliphatic, hydrocarbon residues containing from 2 to about 20 carbon atoms and from 1 to about 5 ether linkages which contain substituent groups such as the halogen hydroxyl, --COOH, and --COOR' groups wherein R' is as defined above.
It is to be understood that where substituent groups are present, they should be such that they do not unduly hinder or interfere with the photocure of the polyfunctional acrylic monomers.
The more preferred polyfunctional acrylic monomers are those represented by formula I wherein R is selected from the group consisting of an n functional saturated aliphatic hydrocarbon residue containing from 1 to about 20 carbon atoms, a hydroxyl substituted n fuhctional saturated aliphatic hydrocarbon residue containing from 1 to about 20 carbon atoms, an n functional saturated aliphatic hydrocarbon residue containing from about 2 to about 20 carbon atoms and from about 1 to about 5 ether linkages, and a hydroxyl substituted n functional saturated aliphatic hydrocarbon residue containing from 2 to about 20 carbo~ atoms and from 1 to about 5 ethe`r linkages.
The preferred polyfunctional acrylate ester monomers are those wherein R is an n funct~ional saturated aliphatic hydrocarbon, ether, or polyether radical, with those monomers wherein ~ is an n valent saturated . . .
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~Z~241~
aliphatic hydrocarbon radical being more preferred.
More particularly, the difunctional acrylic monomers, or diacrylates, are represented by formula I
wherein n is 2; the trifunctional acrylic monomers, or triacrylates, are represented by formula I wherein n is 3; and the tetra-functional acrylic monomers, or : tetraacrylates, are represented by formula I wherein n is 4. Illustrative of suitable polyfunctional acrylate ester ~onomers of formula I are those listed below in TABLE I.
TABLE I
2 CHCO2 - CH2 - OCOCH = CEI
CH2 = CCH3CO2 - CH - OCOCCH3 = CH2 2 = CHC2 ~ CH2CH2 ~ OCOCH = CH2 CH2 = CCEI3C2 ~ CH2CH2 - OCOCCH3 = CH2 CH2 = CH - CO2 - CH2CHOHCH2 - OCOCH =CH2 CH2 = CCH3CO2 - CH2CHOHCH2 - OCOCCH3 = CH2 2 2 CH2CH2 o - CH2CH2 - OCOCH = CH
CH2 = CH2C2 ~ CH2CH2 ~ - CH2cH2 _ OCOCH = CH2 2 2 2 CH2CH~ -- O -- CH2CH -- Q ~' CFI CH
~-~
`. 2 3 2 2 2 2 2 2 2 2 2 3 2 ~, , , .,..,,,`
...`
~2;~
` CH2 = CHco2-cH2cH2cH2 - OCOCH = CH2 CH2 = CCH3CO2 - CH2CH2CH2 - OCOCCH3 = CH2 : 2 2 2 2 2 2 2 CH = CCH3C2 - CH2CH2CH2CH2 - OCOCCH3 = CH2 2 2 CH2CH2CH2CH2CH2 - OCOCH = CH
2 3C2 CH2CH2CH2CH2CH2 - OCOccH3 = CH2 CH2 CHCO2 CH2CH2CH2c 2C 2 2 2 `;; CH2 = CCH3C2 - CH2CH2CH2CH2CH2CH2 _ OCOCCH3 = CH2 CH - CCH CO - CH CH - CHCH - OCOCCH3 = CH2 ` CH2 = CHCO2 - CH2C(CH3)2 CH2 2 CH2 = CCH3C2 - CH2C(CH3)2CH2 - 0 - COCCH3 = CH2 CH2 = CHCO2 - CH2 - C - OCOCH = CH2 ~, C~I2Br : CH2 = CCH3CO2 - CH2 - C - OCOCCH3 = CH2 CH2Br CH
CH2 = CHC2 - CH2 - C - OCOCH = CH2 CH2O~
... . . .
.
:: ~
C 2 CC 3C2 C 2 ~ 3 2 :~ CH20H
CH2 = CHCO2 - CH2 - C - OCOCH = CH2 `;: CH2 = CCH3CO2 - CH2 - C~ - OCOCCH3 ' CH2 : CH20H
:: CH2 = CH - C2 - CH2 - C - OCO - CH = CH2 CH2Br ~ 5 CH2 = CCH3C02 - CH2 - ~C - OCOCCH3 = CH2 `'';`' CH2Br ;~ CEI2 = CHCO2 - CH2 - CH = CH - CH2 - CH2 - OCOCH = CH2 ~ CH2 = CCH3CO2 - CH2 - CH = CH - CH2CH2 - OCOCH = CH2 :~` CH2 = CH2CO2 - CH2 - CH = CH - CH ~ OCOCH = CH2 ," CH2 = CCH3C02 - CH2 - CH = CH - CH - OCOCH = CH2 .;, CH20H
` 10 CH2 = CHCO2 - CH2CHOCH3CH2 - OCOCH = CH2 ' `:
:~`.`.~
CH2 = CCH3CO2 - CH2CHOCH3CH2 - COCCH3 = CH2 : , ``' CH2 = CHCO2 - ~ ~ OCOCH = CH2 CE~2 = CCH3C02 - ~ - ococH3 -- ,CEI2 CH2 = CHC02 - ~ - OCOCH = CH2 CH2 = CCH3CO2 - ~ - OCOCCH3 = CEI2 CH = CHCO2 - ~ - 0 - COCH = CE12 B
CH2 = CCH3C02 6 ~ _ OCOCCH3 = CH2 Br CH2 = CHCO2 - ~ - OCOCH = CH2 CH2 = CCH3CO2 - ~ - OCOCCH3 = CEI2 CH2 = CHCO2 - ~ - CH2CH2 - oCOCH = CH2 .~ ~ .
`' 10 CH2 = CCH3C02 -~ ~ ~- CH2CH2 - 0COCCH3 CH2 ~' ~ .
. .
.
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~Z~82 OCOCH = CH2 CH = CHCO2 - CH CH - CH - CH - OCOCH = CH
OCOCCH3 = CH2 2 C 3 2 C 2C 2 ~C
;; CH2 - OCOCCH3 = CH2 CH2 - OCOCH = CH2 ` C 2 CHCO2 CH2 ~C CH2CH3 CH - OCOCH = CH2 : CH2 - OCOCCH3 = CH2 ~: CH2 - OCOCCH3 = CH2 .'' CH20COCH = CH2 ~ 5 CH2 = CHCO2 - CH2 - C - CH2OH
:~ CH20cOCH = CH2 ;~
OCOCH = CH2 CH2 = CHCo2~3--OCOCH = CH2 :,:
~ OCOCCH3 = CH2 ~., I
~` CH2 = CCH3CO2 ~ 3 2 .~
~ CH20COCH = CH2 `-. CH2 = CH - C2 - CH2 - ~C - CH2OCOCH = CH2 CH20COCH = CH2 .,. ~.,` . `, .:, `. . ` `:: . : . : . ` :
: ` .
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3L2~4~2 7H2OCOCCH3 = CH2 H2 CC~13C2 ~ CH2 - 7 - CH20COCCH3 = CH2 CH20COCCH3 = ,CH2 CH2 - OCOCH = CH2 CH2 = CHC02 - CH2 - CIH - CH - CH20COCH = CH2 CH2 = HCC02 CH2 CIH2 - OCOCCH3 = CH2 2 3 2 - CH2CIH - CH - CH2 - OCOCCH3 = CH2 CH2 = CHC02CIH2 Cl 120COCH = CH2 ~: CH~ = CHC02 - CH2 - CH - CIH - CH2CH - CH2 - OCOCH = CH
: OH
~: CH2 = CCH3C02CH2 OIH20COCCH3 H2 5CH2 = CCH3C02 - CH2 - CH - CIH - CH2CH - CH2 - OCOCCH3 = CH2 OH
CH2 = CHC02CH2CHCH3 - OCH2CHCH30CH2 - CHCH30CO - CH = CH2 CH2 = CH - C02 - CH2CH2 - O - phenyl CH = CCH - CO - CH CH O - phenyl CH2 = CHC02 - CH2 ~Q
CH2 = CCH3C02 CH2 .. :, ` ~
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These polyacry]ate esters and their production are well known to those skilled in the art. One method of producing the di-, tri-, and tetraacrylate esters ; involves reacting acrylic acid with a di-, tri-, or tetrahydroxyl compound to produce the diester, triester or tetraester. Thus, for example, acrylic acid can be reacted with ethylene glycol to produce ethylene glycol diacrylate.
Although the coating compositions may contain only one of said polyfunctional acrylate monomers, preferred coating compositions contain a mixture of two polyfunctional monomers, preferably a diacrylate and a triacrylate. When the coating compositions contain a mixture of acrylate monomers, it is preferred that the ratio, by weight, of the diacrylate to the triacrylate be from about 30/70 to about 70/30. Exemplary mixtures of diacrylates and triacrylates include mixtures of hexanediol diacrylate with pentaerythritol triacrylate, hexanediol diacarylate with trimethylolpropane triacrylate, `~ 20 diethyleneglycol diacrylate with pentaerythritol triacrylate, and diethyleneglycol diacrylate with ~ trlmethylolpropane triacrylate.
;~ While the corresponding coatings may likewise contain the ultra~iolet light reaction product of a single polyfunctional acrylate monomer, coatings containing the photoreaction product of two polyfunctional acrylate monomers, preferably a diacrylate and a triacrylate, are preferred.
Generally, the coating composition contains from about 70 to about 99 percent of the polyfunctional acrylate or acrylates. The UV cured coating contains from about 70 to about 99 weight percent of the photoreaction products of the polyfunctional acrylate monomer or mixture of acrylate monomers present in the coating composition.
qhe photocurable coating compositions also contain a photosensitizing amount of photosensitizer, i.e., an :`
5~ ;. , . .
. :: .. , ::. -;. : : , , , :
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, , :.. -.: '' .' ': ~, ~224~2 amount effective to effect the photocure of the coating composition. Generally, this amount is from about 0.1~
to about 10% by weight and preferably from about 0.1% to about 5~ by weight of the photocurable coating composition.
It has been discovered through the present invention that certain blends of ketone-type and hindered amine type materials are photoinitiators which are effective for crosslinking the above described polyfunctional acrylates to form suitable hard coatings upon exposure to UV radiation. It is preferred that the ratio, by weight, of the ketone compound to the hindered amine compound be from, approximately, 80/20 to 20/80.
Ordinarilly, 50/50 or 60/40 mixtures are quite satisfactory.
Among the particularly preferred ketone-type compounds are those selected from the group consisting of:
benzophenone, and other acetophenones, benzil, benzaldehyde and o-chlorobenzaldehyde, xanthone, thioxanthone, 2-chlorothioxanthone, 9,10-phenanthrenequinone, 9,10-anthraquinone, ethylbenzoin ether, isopropyl benzoin ether, a, a-diethoxyacetophenone, l-phenyl-l 2-propanediol-2-o-benzoyl oxime, and a,a - dimethoxy-a-phenylacetophenone, In the above formulas, lower case a represents configurations of radicals in the alpha position.
Among the particularly preferred hindered amine-type compounds are`those selected from the ~roup consisting of:
methyldiethanol amine, ethyldiethanol amine, dimethylethanol amine, .
~ZZ4182 diethyl ethanol amine, ; triethanol amine, dimethyl amino ethylbenzoate, ethyl-3-dimethyl amino benzoate, ~ 5 4~dimethyl amino benzophenone, ; 4-diethyl amino benzophenone, 4,4' -bis (diethylamino) benzophenone, 4,4' -bis (dimethylamino) benzophenone, N, N-diethyl aniline, phenyl methyl ethanol amine, phenyl ethyl ethanol amine, phenyl diethanol amine, and N,N,N',N' -tetramethyl - 1,3 -butanediamine.
The coating compositions of the instant invention may also optionally contain resorcinol monobenzoate. The resorcinol monobenzoate is present in an amount, based upon ` the weight of the coating composition, exclusive of any additional solvent which may optionally be present, of .:~, ` from about 1 to about 20 weight percent, preferably from about 3 to about 15 weight percent. The UV cured coating ~; contains from about 1 to about 20% by weight of the photoreaction products of resorcinol monobenzoate, which products are formed during the UV cure of the UV curable ` coating composition if the resorcinol monobenzoate is utilized.
The coating compositions of the instant invention may also optionally contain various flatting agents, surface active agents, thi~otropic agentsj UV light - absorbers and dyes. All of thèse additives and the use thereof are weIl known in the art and do not require e~tensive discussions. Therefore, only a limited number will be referred to, it being understood that any compounds possessing the ability to function in such a manner, i.e., as a flatting agent, sur~ace active agent, W light absorber, and the likèj can be used so long as :
- . : :' '' '.. ,, ,, .,. ''.
: ~ ' -. :
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~2;~41~2 ' they do not deleteriously affect the photocuring of the coating compositions and do not adversely affect the non-opaque character of the coating.
The various surface-active agents, including anionic, cationic and nonionic surface-active agents are described inKirk-Othmer Encyclopedia of Chémical Technology, Vol. 19, Interscience Publisher, New York, 1969, pp. 507-593, and Encyclopedia of Polymer Seience and Technology, Vol. 13, Interseience Publishers, New York, 1970, pp. 477-486.
In the practice of the present invention, the photocurable coating compositions are first compounded by adding together the polyfunctional acrylic monomer or mixtures thereof, the W photosensitizer blend, and, optionally, any of the other a-forementioned additives.
Additionally, if so desired to reduce the viscosity of the coating formulation, an organic solvent, such as an alcohol, may optionally be incorporated into the formulation. Generally, the amount of solvent, if any, present shouLd be sueh that evaporation of the solvent ~' occurs before any deleterious effect on the substrate.
The various components are thoroughIy mixed so as to form a generally homogeneous coating compositions. A
thin, uniform coating of the coating solution is then applied onto the substrate by any of the known means sueh ; as dipping, spraying, rolleoating and the like. The eoating is then cured in a non-inert, e.g., air, atmosphere, by W irradiàtion which ean have a wavelength of from 1849 A. to 4000A. The lamp systems used to generate such radiation can consist of ultraviolet lamps which can eonsist of diseharge lamps, as for example, xenon, metallic halide, metallic arc, such as low or high pressure mercury vapor diseharge lamp, ete., having operating pressures of from as low as a few milli-torr up to about 10 atmospheres. By curing is means bbth polymerization . . .
.- ...
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~L2~4~1~2 of the polyfunctional acrylic monomers and cross-linking of the polymers to form hard, non-tacky coatings.
PREFERRED EMBODIMENT OF THE' INVENTI'ON
In order to more fully and clearly describe the invention, it is-intended that the examples be considered as illustra~ive rather than limiting the invention disclosed and claimed herein. All parts are by weight.
An aromatic polycarbonate is prepared by reacting 2,2-bis(4-hydroxyphenyl) propane and phosgene in the presence of an acid acceptor and a molecular weight regulator. The product is then fedto an extruder, which ~; extruder is operated at about 265C and the extrudate is comminuted into pellets.
' 15The pellets are then injection molded at about ~"315C into test panels of about 4 in. by 4 in. by about 1/8fin. thick. The test panels are sub~ected to an abrasion test, Gardner Impact Test and an adhesion test.
The abrasion, test in one wherein test panels having a 17/64th inch diameter hole cut in the center are subjected to a Taber Abraser. The Taber Abraser is equipped with CS-lOF wheels which are resurfaced every 500 cycles by abrading for 25 cycles on a S-lll refacing disc. The weights used in combination with the CS-lOF
wheels are 500 gm weights. Initial measurements of % Haze are made at four places around the future wear track of the sample using a Gardner Hazemeter. The sample is abraded ;for 500 cycles, cleaned with warm soap and water and dried by blowing compressed air across the sample, and the %
Haze is remeasured at the same four places. The four differences in % Haze are'calculated are averaged to give the % Haze.' The ~ % Haze of this uncoated sample is generally between 45 to 50.
~he scribed adhesion tes~ consists of using a ~: , . ~ ,., :
.:
: - .; -, :: , ~ . . :.
::
~4~8~
multiple blade tool to cut parallel grooves through the ; coating and into the substrate. The test panel is then rotated 90 and the cutting process is repeated,,thereby leaving a grid pattern consisting of 1 mm squares cut into i ~ 5 the coating. An adhesive tape such as 3M's Scotch'71~ is applied over the cross hatched area and quickly pulled off.
A sample fails the adhesion test if any of the squares are pulled off by the tape. This test is repeated three times.
Examples 2,3, and 4 are comparative examples of unsuccessful hardcoating compositions utilizing poly-functional acrylate monomers as basic ingredients.
A coating composition was prepared by combining 150 parts of hexanedioldiacrylate (HDDA), 150 parts of trimethylolpropanetriacrylate (TMPTA), 2 parts of '', benzophenone, 2 parts of dimethylethanol amine, and one ' part of a surface active agent BYK-300 produced by Mallincrodt Chemical Co. of New Jersey. A film of about 0.15 mil of this mixture was coated on a polycarbonate panel produced in accordance with example 1. The coated panel was passed thorugh a PPG Model QC 1202 UV-processor under an air atmosphere, where the conveyer speed was 20 feet/minute. Two passes through the system resulted in a coating which'was tacky and undercured.
_ _ .
; A coating composition was formulated by combining 200 parts diethylene glycol diacrylate, 200 parts trimethylolpropanetriacrylate, 2 parts benzophenone, ~ 1.5 parts methyldiethanolamine, and one part B~K-300.
'~ 30 This mixture was-coated on a polycarbonate test paneI which was then twice passed through the PPG UV-processor under an air atmosphere. The resulting coating was-tacky and not fully cured.
~-- ::
~LZ;i:4~32 A coating mixture was formulated by combining 200 grams hexanedioldiacrylate, 200 grams ~rimethylol-propanetriacrylate, 4 grams diethoxyacetophenone, 20 grams resorcinol monobenzoate, and 2 grams BYK-300. A
~ film of about 0.2 mils was applied to a Lexan polycarbonate `~` panel and passed 5 times through the PPG 1202 UV-Processor under a nitrogen blanket of 15 psi and at a conveyor speed of 20 ft./min. The resulting coating was tacky, had cracks and was hazy.
The remaining examples demonstrate the successful hard coating compositions of the present invention.
,:~
A coating mixture was prepared by combining 100 ~' 15 parts of hexanedioldiacrylate, 100 parts of trimethylol-propanetriacrylate, 4 parts by weight of benzophenone, ', 4 parts by weight of methyldiethanolamine, and 1 part by weight of surface active agent BYK-300. This coating composition was applied to a polycarbonate panel and was ,~ 20 then passed through a PPG 1202 W-processor in an air atmosphere where the conveyer speed was 20,ft/min. One pass through this system resulted in a coating which was hard and tack-free.
A coating mixture was prepared by combining 100g of hexanedioldiacrylate, 100g of trimethylolpropanetriacrylate, 4g of benæophenone, 4g of methyldiethanolamine, lg of BYK-300 and 10g of resorcinol monobenzoate. This mixture was coated on LexanR and passed through a UV-Processor as in Example 2. The coated LexanR was subj~ected to the afore-described abrasion and scribed adhèsion tests and the results are set forth in Table II.
EXAMPL~ 7 A coating composition was made by combining 200 g of diethylene glycol diacrylate, 4g of benzophenone, 4g of methyldiethanol amine, and 1 g of BYK-300. This ::. .: .
lZ24~2 coating was applied to a LexanR panel and passed through a W-Processor as in Example 2. The coated Lexan panel ; was also subjected to the afore-described abrasion and scribed-adhesion tests and the results are set forth in Table II.
-~ A coating composition was formulated by combining 100 g of trimethylolpropanetriacylate, 2 g of benzophenone, 2 g of methyldiethanolamine, and 0.5 g o BYK-300. A film .~ 10 of about 0.2 mils thickness was applied to a LexanR sheet and passed through a W-Processor as in Example 2. The coated LexanR panel was subjected to the afore-described abrasion and scribed adhesion tests an'd the results are set forth in Table II.
A coating composition was formulated by combining 250 g of diethylene glycol diacrylate, 250 g : of trimethylolpropane triacylate, lOg of benzophenone, lOg of methyldiethanolamine, and 2.5 g of BYK-300. This :~ 20 material was coated on a LexanR panel and passed through a UV-Processor as in Example 2. The results are set forth in Table II.
: TABLE II
Example No. Adhesion Test~%H500 pass 24.6 6 pass 28.5 7 pass 23.3 8 pass 21.2 9 pass 19.2 Those skilled in the art will recognize that the ~' ~ % H500 haze'data given in Table II represents coated articles having excellent abrasion resistance.
The'foregoing example'demonstrate'that it is possible to pxovide~air curable coating composition through the part.icular combination of polyfunctional acrylates and ''' ., .~
: . . :
.' . " ~
~2Z9L~L~32 blended photoinitiators described above. These coatings and coated articles also possess such other desirable properties as optical clarity~ durability of adhesion, ~;~ non-degradation of the properties of the substrate, and protection of the substrate from the ~e~cr~5 effects of prolonged exposure to W.
Although specific embodiments of the invention ~: have been described, it should not be limited to the - particular compositions and articles described herein, but is intended to include all modifications that may be made which, pursuant to the patent statutes and laws, do not depart from the spirit and scope of the invention.
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CH2 = CCH3CO2 - CH - OCOCCH3 = CH2 2 = CHC2 ~ CH2CH2 ~ OCOCH = CH2 CH2 = CCEI3C2 ~ CH2CH2 - OCOCCH3 = CH2 CH2 = CH - CO2 - CH2CHOHCH2 - OCOCH =CH2 CH2 = CCH3CO2 - CH2CHOHCH2 - OCOCCH3 = CH2 2 2 CH2CH2 o - CH2CH2 - OCOCH = CH
CH2 = CH2C2 ~ CH2CH2 ~ - CH2cH2 _ OCOCH = CH2 2 2 2 CH2CH~ -- O -- CH2CH -- Q ~' CFI CH
~-~
`. 2 3 2 2 2 2 2 2 2 2 2 3 2 ~, , , .,..,,,`
...`
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` CH2 = CHco2-cH2cH2cH2 - OCOCH = CH2 CH2 = CCH3CO2 - CH2CH2CH2 - OCOCCH3 = CH2 : 2 2 2 2 2 2 2 CH = CCH3C2 - CH2CH2CH2CH2 - OCOCCH3 = CH2 2 2 CH2CH2CH2CH2CH2 - OCOCH = CH
2 3C2 CH2CH2CH2CH2CH2 - OCOccH3 = CH2 CH2 CHCO2 CH2CH2CH2c 2C 2 2 2 `;; CH2 = CCH3C2 - CH2CH2CH2CH2CH2CH2 _ OCOCCH3 = CH2 CH - CCH CO - CH CH - CHCH - OCOCCH3 = CH2 ` CH2 = CHCO2 - CH2C(CH3)2 CH2 2 CH2 = CCH3C2 - CH2C(CH3)2CH2 - 0 - COCCH3 = CH2 CH2 = CHCO2 - CH2 - C - OCOCH = CH2 ~, C~I2Br : CH2 = CCH3CO2 - CH2 - C - OCOCCH3 = CH2 CH2Br CH
CH2 = CHC2 - CH2 - C - OCOCH = CH2 CH2O~
... . . .
.
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C 2 CC 3C2 C 2 ~ 3 2 :~ CH20H
CH2 = CHCO2 - CH2 - C - OCOCH = CH2 `;: CH2 = CCH3CO2 - CH2 - C~ - OCOCCH3 ' CH2 : CH20H
:: CH2 = CH - C2 - CH2 - C - OCO - CH = CH2 CH2Br ~ 5 CH2 = CCH3C02 - CH2 - ~C - OCOCCH3 = CH2 `'';`' CH2Br ;~ CEI2 = CHCO2 - CH2 - CH = CH - CH2 - CH2 - OCOCH = CH2 ~ CH2 = CCH3CO2 - CH2 - CH = CH - CH2CH2 - OCOCH = CH2 :~` CH2 = CH2CO2 - CH2 - CH = CH - CH ~ OCOCH = CH2 ," CH2 = CCH3C02 - CH2 - CH = CH - CH - OCOCH = CH2 .;, CH20H
` 10 CH2 = CHCO2 - CH2CHOCH3CH2 - OCOCH = CH2 ' `:
:~`.`.~
CH2 = CCH3CO2 - CH2CHOCH3CH2 - COCCH3 = CH2 : , ``' CH2 = CHCO2 - ~ ~ OCOCH = CH2 CE~2 = CCH3C02 - ~ - ococH3 -- ,CEI2 CH2 = CHC02 - ~ - OCOCH = CH2 CH2 = CCH3CO2 - ~ - OCOCCH3 = CEI2 CH = CHCO2 - ~ - 0 - COCH = CE12 B
CH2 = CCH3C02 6 ~ _ OCOCCH3 = CH2 Br CH2 = CHCO2 - ~ - OCOCH = CH2 CH2 = CCH3CO2 - ~ - OCOCCH3 = CEI2 CH2 = CHCO2 - ~ - CH2CH2 - oCOCH = CH2 .~ ~ .
`' 10 CH2 = CCH3C02 -~ ~ ~- CH2CH2 - 0COCCH3 CH2 ~' ~ .
. .
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~Z~82 OCOCH = CH2 CH = CHCO2 - CH CH - CH - CH - OCOCH = CH
OCOCCH3 = CH2 2 C 3 2 C 2C 2 ~C
;; CH2 - OCOCCH3 = CH2 CH2 - OCOCH = CH2 ` C 2 CHCO2 CH2 ~C CH2CH3 CH - OCOCH = CH2 : CH2 - OCOCCH3 = CH2 ~: CH2 - OCOCCH3 = CH2 .'' CH20COCH = CH2 ~ 5 CH2 = CHCO2 - CH2 - C - CH2OH
:~ CH20cOCH = CH2 ;~
OCOCH = CH2 CH2 = CHCo2~3--OCOCH = CH2 :,:
~ OCOCCH3 = CH2 ~., I
~` CH2 = CCH3CO2 ~ 3 2 .~
~ CH20COCH = CH2 `-. CH2 = CH - C2 - CH2 - ~C - CH2OCOCH = CH2 CH20COCH = CH2 .,. ~.,` . `, .:, `. . ` `:: . : . : . ` :
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3L2~4~2 7H2OCOCCH3 = CH2 H2 CC~13C2 ~ CH2 - 7 - CH20COCCH3 = CH2 CH20COCCH3 = ,CH2 CH2 - OCOCH = CH2 CH2 = CHC02 - CH2 - CIH - CH - CH20COCH = CH2 CH2 = HCC02 CH2 CIH2 - OCOCCH3 = CH2 2 3 2 - CH2CIH - CH - CH2 - OCOCCH3 = CH2 CH2 = CHC02CIH2 Cl 120COCH = CH2 ~: CH~ = CHC02 - CH2 - CH - CIH - CH2CH - CH2 - OCOCH = CH
: OH
~: CH2 = CCH3C02CH2 OIH20COCCH3 H2 5CH2 = CCH3C02 - CH2 - CH - CIH - CH2CH - CH2 - OCOCCH3 = CH2 OH
CH2 = CHC02CH2CHCH3 - OCH2CHCH30CH2 - CHCH30CO - CH = CH2 CH2 = CH - C02 - CH2CH2 - O - phenyl CH = CCH - CO - CH CH O - phenyl CH2 = CHC02 - CH2 ~Q
CH2 = CCH3C02 CH2 .. :, ` ~
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These polyacry]ate esters and their production are well known to those skilled in the art. One method of producing the di-, tri-, and tetraacrylate esters ; involves reacting acrylic acid with a di-, tri-, or tetrahydroxyl compound to produce the diester, triester or tetraester. Thus, for example, acrylic acid can be reacted with ethylene glycol to produce ethylene glycol diacrylate.
Although the coating compositions may contain only one of said polyfunctional acrylate monomers, preferred coating compositions contain a mixture of two polyfunctional monomers, preferably a diacrylate and a triacrylate. When the coating compositions contain a mixture of acrylate monomers, it is preferred that the ratio, by weight, of the diacrylate to the triacrylate be from about 30/70 to about 70/30. Exemplary mixtures of diacrylates and triacrylates include mixtures of hexanediol diacrylate with pentaerythritol triacrylate, hexanediol diacarylate with trimethylolpropane triacrylate, `~ 20 diethyleneglycol diacrylate with pentaerythritol triacrylate, and diethyleneglycol diacrylate with ~ trlmethylolpropane triacrylate.
;~ While the corresponding coatings may likewise contain the ultra~iolet light reaction product of a single polyfunctional acrylate monomer, coatings containing the photoreaction product of two polyfunctional acrylate monomers, preferably a diacrylate and a triacrylate, are preferred.
Generally, the coating composition contains from about 70 to about 99 percent of the polyfunctional acrylate or acrylates. The UV cured coating contains from about 70 to about 99 weight percent of the photoreaction products of the polyfunctional acrylate monomer or mixture of acrylate monomers present in the coating composition.
qhe photocurable coating compositions also contain a photosensitizing amount of photosensitizer, i.e., an :`
5~ ;. , . .
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, , :.. -.: '' .' ': ~, ~224~2 amount effective to effect the photocure of the coating composition. Generally, this amount is from about 0.1~
to about 10% by weight and preferably from about 0.1% to about 5~ by weight of the photocurable coating composition.
It has been discovered through the present invention that certain blends of ketone-type and hindered amine type materials are photoinitiators which are effective for crosslinking the above described polyfunctional acrylates to form suitable hard coatings upon exposure to UV radiation. It is preferred that the ratio, by weight, of the ketone compound to the hindered amine compound be from, approximately, 80/20 to 20/80.
Ordinarilly, 50/50 or 60/40 mixtures are quite satisfactory.
Among the particularly preferred ketone-type compounds are those selected from the group consisting of:
benzophenone, and other acetophenones, benzil, benzaldehyde and o-chlorobenzaldehyde, xanthone, thioxanthone, 2-chlorothioxanthone, 9,10-phenanthrenequinone, 9,10-anthraquinone, ethylbenzoin ether, isopropyl benzoin ether, a, a-diethoxyacetophenone, l-phenyl-l 2-propanediol-2-o-benzoyl oxime, and a,a - dimethoxy-a-phenylacetophenone, In the above formulas, lower case a represents configurations of radicals in the alpha position.
Among the particularly preferred hindered amine-type compounds are`those selected from the ~roup consisting of:
methyldiethanol amine, ethyldiethanol amine, dimethylethanol amine, .
~ZZ4182 diethyl ethanol amine, ; triethanol amine, dimethyl amino ethylbenzoate, ethyl-3-dimethyl amino benzoate, ~ 5 4~dimethyl amino benzophenone, ; 4-diethyl amino benzophenone, 4,4' -bis (diethylamino) benzophenone, 4,4' -bis (dimethylamino) benzophenone, N, N-diethyl aniline, phenyl methyl ethanol amine, phenyl ethyl ethanol amine, phenyl diethanol amine, and N,N,N',N' -tetramethyl - 1,3 -butanediamine.
The coating compositions of the instant invention may also optionally contain resorcinol monobenzoate. The resorcinol monobenzoate is present in an amount, based upon ` the weight of the coating composition, exclusive of any additional solvent which may optionally be present, of .:~, ` from about 1 to about 20 weight percent, preferably from about 3 to about 15 weight percent. The UV cured coating ~; contains from about 1 to about 20% by weight of the photoreaction products of resorcinol monobenzoate, which products are formed during the UV cure of the UV curable ` coating composition if the resorcinol monobenzoate is utilized.
The coating compositions of the instant invention may also optionally contain various flatting agents, surface active agents, thi~otropic agentsj UV light - absorbers and dyes. All of thèse additives and the use thereof are weIl known in the art and do not require e~tensive discussions. Therefore, only a limited number will be referred to, it being understood that any compounds possessing the ability to function in such a manner, i.e., as a flatting agent, sur~ace active agent, W light absorber, and the likèj can be used so long as :
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~2;~41~2 ' they do not deleteriously affect the photocuring of the coating compositions and do not adversely affect the non-opaque character of the coating.
The various surface-active agents, including anionic, cationic and nonionic surface-active agents are described inKirk-Othmer Encyclopedia of Chémical Technology, Vol. 19, Interscience Publisher, New York, 1969, pp. 507-593, and Encyclopedia of Polymer Seience and Technology, Vol. 13, Interseience Publishers, New York, 1970, pp. 477-486.
In the practice of the present invention, the photocurable coating compositions are first compounded by adding together the polyfunctional acrylic monomer or mixtures thereof, the W photosensitizer blend, and, optionally, any of the other a-forementioned additives.
Additionally, if so desired to reduce the viscosity of the coating formulation, an organic solvent, such as an alcohol, may optionally be incorporated into the formulation. Generally, the amount of solvent, if any, present shouLd be sueh that evaporation of the solvent ~' occurs before any deleterious effect on the substrate.
The various components are thoroughIy mixed so as to form a generally homogeneous coating compositions. A
thin, uniform coating of the coating solution is then applied onto the substrate by any of the known means sueh ; as dipping, spraying, rolleoating and the like. The eoating is then cured in a non-inert, e.g., air, atmosphere, by W irradiàtion which ean have a wavelength of from 1849 A. to 4000A. The lamp systems used to generate such radiation can consist of ultraviolet lamps which can eonsist of diseharge lamps, as for example, xenon, metallic halide, metallic arc, such as low or high pressure mercury vapor diseharge lamp, ete., having operating pressures of from as low as a few milli-torr up to about 10 atmospheres. By curing is means bbth polymerization . . .
.- ...
: ,~ ' - :. :
;:
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~L2~4~1~2 of the polyfunctional acrylic monomers and cross-linking of the polymers to form hard, non-tacky coatings.
PREFERRED EMBODIMENT OF THE' INVENTI'ON
In order to more fully and clearly describe the invention, it is-intended that the examples be considered as illustra~ive rather than limiting the invention disclosed and claimed herein. All parts are by weight.
An aromatic polycarbonate is prepared by reacting 2,2-bis(4-hydroxyphenyl) propane and phosgene in the presence of an acid acceptor and a molecular weight regulator. The product is then fedto an extruder, which ~; extruder is operated at about 265C and the extrudate is comminuted into pellets.
' 15The pellets are then injection molded at about ~"315C into test panels of about 4 in. by 4 in. by about 1/8fin. thick. The test panels are sub~ected to an abrasion test, Gardner Impact Test and an adhesion test.
The abrasion, test in one wherein test panels having a 17/64th inch diameter hole cut in the center are subjected to a Taber Abraser. The Taber Abraser is equipped with CS-lOF wheels which are resurfaced every 500 cycles by abrading for 25 cycles on a S-lll refacing disc. The weights used in combination with the CS-lOF
wheels are 500 gm weights. Initial measurements of % Haze are made at four places around the future wear track of the sample using a Gardner Hazemeter. The sample is abraded ;for 500 cycles, cleaned with warm soap and water and dried by blowing compressed air across the sample, and the %
Haze is remeasured at the same four places. The four differences in % Haze are'calculated are averaged to give the % Haze.' The ~ % Haze of this uncoated sample is generally between 45 to 50.
~he scribed adhesion tes~ consists of using a ~: , . ~ ,., :
.:
: - .; -, :: , ~ . . :.
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multiple blade tool to cut parallel grooves through the ; coating and into the substrate. The test panel is then rotated 90 and the cutting process is repeated,,thereby leaving a grid pattern consisting of 1 mm squares cut into i ~ 5 the coating. An adhesive tape such as 3M's Scotch'71~ is applied over the cross hatched area and quickly pulled off.
A sample fails the adhesion test if any of the squares are pulled off by the tape. This test is repeated three times.
Examples 2,3, and 4 are comparative examples of unsuccessful hardcoating compositions utilizing poly-functional acrylate monomers as basic ingredients.
A coating composition was prepared by combining 150 parts of hexanedioldiacrylate (HDDA), 150 parts of trimethylolpropanetriacrylate (TMPTA), 2 parts of '', benzophenone, 2 parts of dimethylethanol amine, and one ' part of a surface active agent BYK-300 produced by Mallincrodt Chemical Co. of New Jersey. A film of about 0.15 mil of this mixture was coated on a polycarbonate panel produced in accordance with example 1. The coated panel was passed thorugh a PPG Model QC 1202 UV-processor under an air atmosphere, where the conveyer speed was 20 feet/minute. Two passes through the system resulted in a coating which'was tacky and undercured.
_ _ .
; A coating composition was formulated by combining 200 parts diethylene glycol diacrylate, 200 parts trimethylolpropanetriacrylate, 2 parts benzophenone, ~ 1.5 parts methyldiethanolamine, and one part B~K-300.
'~ 30 This mixture was-coated on a polycarbonate test paneI which was then twice passed through the PPG UV-processor under an air atmosphere. The resulting coating was-tacky and not fully cured.
~-- ::
~LZ;i:4~32 A coating mixture was formulated by combining 200 grams hexanedioldiacrylate, 200 grams ~rimethylol-propanetriacrylate, 4 grams diethoxyacetophenone, 20 grams resorcinol monobenzoate, and 2 grams BYK-300. A
~ film of about 0.2 mils was applied to a Lexan polycarbonate `~` panel and passed 5 times through the PPG 1202 UV-Processor under a nitrogen blanket of 15 psi and at a conveyor speed of 20 ft./min. The resulting coating was tacky, had cracks and was hazy.
The remaining examples demonstrate the successful hard coating compositions of the present invention.
,:~
A coating mixture was prepared by combining 100 ~' 15 parts of hexanedioldiacrylate, 100 parts of trimethylol-propanetriacrylate, 4 parts by weight of benzophenone, ', 4 parts by weight of methyldiethanolamine, and 1 part by weight of surface active agent BYK-300. This coating composition was applied to a polycarbonate panel and was ,~ 20 then passed through a PPG 1202 W-processor in an air atmosphere where the conveyer speed was 20,ft/min. One pass through this system resulted in a coating which was hard and tack-free.
A coating mixture was prepared by combining 100g of hexanedioldiacrylate, 100g of trimethylolpropanetriacrylate, 4g of benæophenone, 4g of methyldiethanolamine, lg of BYK-300 and 10g of resorcinol monobenzoate. This mixture was coated on LexanR and passed through a UV-Processor as in Example 2. The coated LexanR was subj~ected to the afore-described abrasion and scribed adhèsion tests and the results are set forth in Table II.
EXAMPL~ 7 A coating composition was made by combining 200 g of diethylene glycol diacrylate, 4g of benzophenone, 4g of methyldiethanol amine, and 1 g of BYK-300. This ::. .: .
lZ24~2 coating was applied to a LexanR panel and passed through a W-Processor as in Example 2. The coated Lexan panel ; was also subjected to the afore-described abrasion and scribed-adhesion tests and the results are set forth in Table II.
-~ A coating composition was formulated by combining 100 g of trimethylolpropanetriacylate, 2 g of benzophenone, 2 g of methyldiethanolamine, and 0.5 g o BYK-300. A film .~ 10 of about 0.2 mils thickness was applied to a LexanR sheet and passed through a W-Processor as in Example 2. The coated LexanR panel was subjected to the afore-described abrasion and scribed adhesion tests an'd the results are set forth in Table II.
A coating composition was formulated by combining 250 g of diethylene glycol diacrylate, 250 g : of trimethylolpropane triacylate, lOg of benzophenone, lOg of methyldiethanolamine, and 2.5 g of BYK-300. This :~ 20 material was coated on a LexanR panel and passed through a UV-Processor as in Example 2. The results are set forth in Table II.
: TABLE II
Example No. Adhesion Test~%H500 pass 24.6 6 pass 28.5 7 pass 23.3 8 pass 21.2 9 pass 19.2 Those skilled in the art will recognize that the ~' ~ % H500 haze'data given in Table II represents coated articles having excellent abrasion resistance.
The'foregoing example'demonstrate'that it is possible to pxovide~air curable coating composition through the part.icular combination of polyfunctional acrylates and ''' ., .~
: . . :
.' . " ~
~2Z9L~L~32 blended photoinitiators described above. These coatings and coated articles also possess such other desirable properties as optical clarity~ durability of adhesion, ~;~ non-degradation of the properties of the substrate, and protection of the substrate from the ~e~cr~5 effects of prolonged exposure to W.
Although specific embodiments of the invention ~: have been described, it should not be limited to the - particular compositions and articles described herein, but is intended to include all modifications that may be made which, pursuant to the patent statutes and laws, do not depart from the spirit and scope of the invention.
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.
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Claims (9)
1. A process for providing an abrasion resistant, durably adhered/ ultraviolet light curable hard coating composition which is curable in a non-inert atmosphere, consisting essentially of the steps of:
(1) mixing (A) at least one ultraviolet light cross-linkable polyfunctional acrylate monomer represented by the general formula wherein n is an integer having a value of from l to 4, R is selected from the group consisting of substituted or unsubstituted n valent aliphatic hydrocarbon residue, n valent aliphatic hydrocarbon residue containing at least one ether linkage, and substituted n valent aliphatic hydrocarbon residue containing at least one ether linkage, and R' is selected from hydrogen or lower alkyl radicals; and (B) at least approximately 4.0% by weight to about 10% by weight of a photoinitiator comprised of a blend of (i) at least 2.0% by weight of one or more ketones and (ii) at least 2.0% by weight of one or more hindered amines, wherein said photoinitiator blend is effective for cross-linking (A) upon exposure to ultraviolet radiation;
(2) applying said mixture from (1) to a substrate; and (3) curing said hard coating composition by exposure to an amount of ultraviolet radiation effective for cross-linking acrylate monomer (A).
(1) mixing (A) at least one ultraviolet light cross-linkable polyfunctional acrylate monomer represented by the general formula wherein n is an integer having a value of from l to 4, R is selected from the group consisting of substituted or unsubstituted n valent aliphatic hydrocarbon residue, n valent aliphatic hydrocarbon residue containing at least one ether linkage, and substituted n valent aliphatic hydrocarbon residue containing at least one ether linkage, and R' is selected from hydrogen or lower alkyl radicals; and (B) at least approximately 4.0% by weight to about 10% by weight of a photoinitiator comprised of a blend of (i) at least 2.0% by weight of one or more ketones and (ii) at least 2.0% by weight of one or more hindered amines, wherein said photoinitiator blend is effective for cross-linking (A) upon exposure to ultraviolet radiation;
(2) applying said mixture from (1) to a substrate; and (3) curing said hard coating composition by exposure to an amount of ultraviolet radiation effective for cross-linking acrylate monomer (A).
2. A process as in claim 1 wherein said ketone is selected from the group consisting of:
benzophenone, acetophenone, benzil, benzaldehyde, o-chlorobenzaldehyde, xanthone, thioxanthone, 2-chlorothioxanthone, 9,10-phenanthrenequinone, 9,10-anthraquinone, ethylbenzoin ether, isopropyl benzoin ether, ?,?-dimethoxy-?-phenylacetophenone, ?,?(-diethoxyacetophenone, and 1-phenyl-1,2-propanediol-2-o-benzoil oxime.
benzophenone, acetophenone, benzil, benzaldehyde, o-chlorobenzaldehyde, xanthone, thioxanthone, 2-chlorothioxanthone, 9,10-phenanthrenequinone, 9,10-anthraquinone, ethylbenzoin ether, isopropyl benzoin ether, ?,?-dimethoxy-?-phenylacetophenone, ?,?(-diethoxyacetophenone, and 1-phenyl-1,2-propanediol-2-o-benzoil oxime.
3. A process as in claim 2 wherein said hindered amine is selected from the group consisting of:
methyldiethanol amine, ethyldiethanol amine, dimethylethanol amine, diethylethanol amine, triethanol amine, dimethylamino ethylbenzoate, ethyl-3-dimethyl amino benzoate, 4-dimethyl amino benzophenone, 4-diethyl aminobenzophenone, 4,4'-bis(diethylamine) benzophenone, 4,4'-bis(dimethylamine) benzophenone, N,N-diethyl aniline, phenyl methyl ethanol amine, phenyl ethyl ethanol amine, phenyl diethanol amine, and N,N,N',N'-tetramethyl-1,3-butanediamine.
methyldiethanol amine, ethyldiethanol amine, dimethylethanol amine, diethylethanol amine, triethanol amine, dimethylamino ethylbenzoate, ethyl-3-dimethyl amino benzoate, 4-dimethyl amino benzophenone, 4-diethyl aminobenzophenone, 4,4'-bis(diethylamine) benzophenone, 4,4'-bis(dimethylamine) benzophenone, N,N-diethyl aniline, phenyl methyl ethanol amine, phenyl ethyl ethanol amine, phenyl diethanol amine, and N,N,N',N'-tetramethyl-1,3-butanediamine.
4. A process as in claim 1 further consisting essentially of the step of mixing an ultraviolet light screening agent into said hard coating composition.
5. A process as in claim 4 wherein an anti-weathering agent is used is selected from resorcinol mono-benzoate, resorcinol dibenzoate, methyl resorcinol mono-benzoate and methyl resorcinol dibenzoate.
6. A process as in claim 1 further consisting essentially of a surface active agent.
7. A process as in claim 6 wherein said photoinitiator blend consists essentially of benzophenone and methyldiethanol amine.
8. A process as in claim 1 wherein said composition contains a mixture of hexanediol diacrylate and trimethylolpropane triacrylate monomers.
9. A process as in claim 1 wherein said non-inert atmosphere is air.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US20414680A | 1980-11-05 | 1980-11-05 | |
| US204,146 | 1980-11-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1224182A true CA1224182A (en) | 1987-07-14 |
Family
ID=22756818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389085A Expired CA1224182A (en) | 1980-11-05 | 1981-10-30 | Abrasion resistant ultraviolet light curable hard coating compositions |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1224182A (en) |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6464484B1 (en) | 2002-03-30 | 2002-10-15 | Q2100, Inc. | Apparatus and system for the production of plastic lenses |
| US6612828B2 (en) | 2001-02-20 | 2003-09-02 | Q2100, Inc. | Fill system with controller for monitoring use |
| US6632535B1 (en) | 2000-06-08 | 2003-10-14 | Q2100, Inc. | Method of forming antireflective coatings |
| US6655946B2 (en) | 2001-02-20 | 2003-12-02 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a controller for conveyor and curing units |
| US6676399B1 (en) | 2001-02-20 | 2004-01-13 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having sensors for tracking mold assemblies |
| US6676398B2 (en) | 2001-02-20 | 2004-01-13 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a prescription reader |
| US6702564B2 (en) | 2001-02-20 | 2004-03-09 | Q2100, Inc. | System for preparing an eyeglass lens using colored mold holders |
| US6709257B2 (en) | 2001-02-20 | 2004-03-23 | Q2100, Inc. | Eyeglass lens forming apparatus with sensor |
| US6712596B1 (en) | 1997-07-31 | 2004-03-30 | Q2100, Inc. | System for producing ultraviolet blocking lenses |
| US6712331B2 (en) | 2001-02-20 | 2004-03-30 | Q2100, Inc. | Holder for mold assemblies with indicia |
| US6726463B2 (en) | 2001-02-20 | 2004-04-27 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a dual computer system controller |
| US6752613B2 (en) | 2001-02-20 | 2004-06-22 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a controller for initiation of lens curing |
| US6758663B2 (en) | 2001-02-20 | 2004-07-06 | Q2100, Inc. | System for preparing eyeglass lenses with a high volume curing unit |
| US6790024B2 (en) | 2001-02-20 | 2004-09-14 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having multiple conveyor systems |
| US6790022B1 (en) | 2001-02-20 | 2004-09-14 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a movable lamp mount |
| US6808381B2 (en) | 2001-02-20 | 2004-10-26 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a controller |
| US7129008B2 (en) | 1999-10-12 | 2006-10-31 | Laser Photonics Technology Inc. | Holographic recording material |
-
1981
- 1981-10-30 CA CA000389085A patent/CA1224182A/en not_active Expired
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6712596B1 (en) | 1997-07-31 | 2004-03-30 | Q2100, Inc. | System for producing ultraviolet blocking lenses |
| US7129008B2 (en) | 1999-10-12 | 2006-10-31 | Laser Photonics Technology Inc. | Holographic recording material |
| US6632535B1 (en) | 2000-06-08 | 2003-10-14 | Q2100, Inc. | Method of forming antireflective coatings |
| US6676399B1 (en) | 2001-02-20 | 2004-01-13 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having sensors for tracking mold assemblies |
| US6726463B2 (en) | 2001-02-20 | 2004-04-27 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a dual computer system controller |
| US6676398B2 (en) | 2001-02-20 | 2004-01-13 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a prescription reader |
| US6702564B2 (en) | 2001-02-20 | 2004-03-09 | Q2100, Inc. | System for preparing an eyeglass lens using colored mold holders |
| US6709257B2 (en) | 2001-02-20 | 2004-03-23 | Q2100, Inc. | Eyeglass lens forming apparatus with sensor |
| US6655946B2 (en) | 2001-02-20 | 2003-12-02 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a controller for conveyor and curing units |
| US6712331B2 (en) | 2001-02-20 | 2004-03-30 | Q2100, Inc. | Holder for mold assemblies with indicia |
| US6612828B2 (en) | 2001-02-20 | 2003-09-02 | Q2100, Inc. | Fill system with controller for monitoring use |
| US6752613B2 (en) | 2001-02-20 | 2004-06-22 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a controller for initiation of lens curing |
| US6758663B2 (en) | 2001-02-20 | 2004-07-06 | Q2100, Inc. | System for preparing eyeglass lenses with a high volume curing unit |
| US6790024B2 (en) | 2001-02-20 | 2004-09-14 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having multiple conveyor systems |
| US6790022B1 (en) | 2001-02-20 | 2004-09-14 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a movable lamp mount |
| US6808381B2 (en) | 2001-02-20 | 2004-10-26 | Q2100, Inc. | Apparatus for preparing an eyeglass lens having a controller |
| US6464484B1 (en) | 2002-03-30 | 2002-10-15 | Q2100, Inc. | Apparatus and system for the production of plastic lenses |
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