PHOTOINITIATOR COMPOSITION INCLUDING HINDERED AMINE STABILIZER

Abstract: The present invention relates to a photoinitiator composition that can be used to initiate polymerization upon exposure to radiation. The said composition includes both a composition which yields cations upon exposure to actinic radiation, such as an iodonium borate initiator and a stabilizing amino agent. The amino agent is a secondary or tertiary amine having general formula (VIII), a sterically arranged cyclic amine having general formula (IX), or an amine consisting of groups that have general formulas (VIII) and (IX) and that are interconnected. The compositions are particularly useful when used in conjunction with polyorganosiloxane monomers and when exposed to ultraviolet radiation.

Description: PHOTOINITIATOR COMPOSITION INCLUDING HINDERED AMINE STABILIZER Background of the Invention 1 Field of the Invention The present invention relates to stable photoinitiator compositions used to polymeπze or crosslink another composition containing polymenzable or crosslinkable groups. More specifically, the compositions include both a compound which liberates cations upon exposure to actinic radiation, preferably an lodonium borate, and a hindered amine. The hindered amine acts to stabilize the composition to provide it with an extended shelf-life, particularly when the cationic liberating compound is present in a diluent liquid. 2. Technology Descπption It is known that anti-adhesive coatings can be obtained through the use of compositions having a base of a polyorganosiloxane with functional groups (of the epoxy or vinyl ether type, etc.), to which a cationic onium salt is added in order to function as a polymerization initiator (see U.S. patents No. US-A-4 450 360, No. US-A-4 576 999, and No. US-A-4 640 967). It has been observed that the best results are obtained with onium salts whose anion is SbFg " . However, the initiators that contain this type of anion are difficult to handle and can pose significant toxicity πsks. The compound used as the photoinitiator is typically a solid, but for practical applications and to provide enhanced performance is often maintained in a liquid form by dissolving or dispersing it in a diluent. An example of this type of technology is described in U.S. Patent No. 5,703,137 wherein ester diluents, such as n-butyl lactate are used as reactive diluents for onium salt p otoinitiators. When the photoinitiator is stored in liquid form, it can have a tendency to degrade and to display a reduced level of performance if it is used after having been stored for a long time. While not wishing to be bound by any specific theory, the inventors hypothesize that some cations must be liberated from the photoinitiator dunng the storing period. In addition, when selecting certain diluents for the photoinitiator, it is believed that a minute amount of a premature reaction between the diluent with the cations generated from the photoinitiator compound may yield potentially harmful by-products. O 99/35188 Accordingly, there exists a need in the art for a photoinitiator composition having excellent stability and which does not release potentially harmful by-products when used. Summary of the Invention In accordance with the present invention there is provided a cationic photoinitiator composition having excellent stability and which does not release potentially harmful by-products when used. More specifically, the inventors have surprisingly discovered that the stability and toxiαty properties of cationic photoinitiators can be significantly improved by assooating with the cationic compound a hindered amine More specifically, a first embodiment of the present invention provides a composition compπsing (a) a compound which liberates cations upon exposure to actinic radiation; and (b) an amine stabilizer In particularly preferred embodiments, the compound which liberates cations upon exposure to actinic radiation is an onium borate, even more preferably an lodonium borate, and the hindered amine includes one or more secondary or tertiary ammo groups. In still other preferred embodiments, the composition further includes a reactive or non-reactive diluent, with dtacetone alcohol being particularly preferred The photoinitiator composition is used to polymerize or crosslink one or more mateπals containing polymeπzable or crossiinkable groups. It is particularly preferred that the novel initiators be used to initiate crosslinking of polyorganosiloxane mateπals including one or more crossiinkable groups such as vinyl or epoxy groups. The photoinitiator can also be used to polymerize or crosslink non-silicone containing mateπals which contain epoxy groups. Another embodiment of the present invention is directed to a method for pd ymeπzing or crosslinking a composition compπsing the steps of (1) providing a compound having poiymeπzable or crossiinkable groups; (2) adding to the compound a crosslinking or polymerizing effective amount of an initiator composition compπsing- O 99/35188 3 (a) a compound which liberates cations upon exposure to actinic radiation, and (b) a hindered amine stabilizer (3) exposing the resulting composition to actinic radiation so that the initiator composition yields one or more cations and (4) cationically polymeπzing or crosslinking the polymeπzable or crossiinkable groups It is an object of the present invention to provide a photoinitiator composition which has excellent stability properties It is a further object of the present invention to provide a photoinitiator composition which does not yield a significant amount of toxic by-products when stored and/or used. A still further object of the present invention is to provide a process for using the novel photoinitiator These and other objects will be readily apparent to those skilled in the art as reference is made to the detailed descπption of the preferred embodiment Detailed Descnption of the Preferred Embodiment In descπbing the preferred embodiment certain terminology will be utilized for the sake of claπty Such terminology is intended to encompass the recited embodiment, as well as ail technical equivalents which operate in a similar manner for a similar purpose to achieve a similar result The inventors have discovered and refined new cationic photoinitiator compositions useful for initiating polymerization or crosslinking of compounds having polymeπzable or crossiinkable functional groups that display virtually none of the disadvantages of the compositions descπbed in the pπσr art In particular, the said new compositions include a stabilizing ammo agent and display greatly improved stability dunng storage and duπng use Moreover uncontrolled polymeπzation reactions within the compositions are virtually eliminated, without inhibiting the ability of the said compositions to crosslink under controlled conditions The new compositions in accordance with the invention consist basically of the following components - a compound that yields cations upon exposure to actinic radiation, and particularly exposure to ultraviolet (UV) radiation (i e , "the photoinitiator") , and - an amiho agent which has properties that noticeably improves the stability duπng storage and use of the photoinitiator The compound which liberates cations upon exposure to actinic radiation in accordance with the invention compπses any compound or mixture of compounds which can liberate one or more cations upon exposure to actinic radiation (e g., infrared, electron beam, visible light or ultraviolet radiation), and preferably is deπved from onium salts. In particular, the onium salts are selected from among at least one element that is selected from groups 15 to 17 in the peπodic table (Chβm 4 Eng News, Vol. 63, N* 5 (February 4, 1985), p. 26) and whose cationic entity and anionic entity are defined herembeiow. Mixtures of photoinitiators are specifically contemplated as failing within the scope of the present invention. The cationic entity of the onium salt is selected from among- (1) The onium salts that have the formula [(Rι) n - A -(R2)m- + 0 in which: - "A" represents an element in a group from 15 to 17, such as I, S, Se, P, and N; - The Rf symbol represents a carbocyciic or heterocyciic aryl radical that has from 6 to 20 carbon atoms, which is preferably phenyl, tolyl or toiuyl, with the said heterocyciic radical optionally containing at least one heteroatom, which is preferably nitrogen and/or sulfur - The P * 2 symbol represents R-j, an alkyl radical, or a linear or branched alkenyl radical containing from 1 to 30 carbon atoms; - The said Ri and R2 radicals may optionally be substituted by one or more of the following: an alkoxy group that contains from 1 to 25 carbon atoms, an alkyl group containing from 1 to 25 carbon atoms; a nitro group, a chloro group, a bromo group, a cyano group, a carboxyl group, and/or a mercapto group, - n is an integer ranging from 1 to v+1 , where v is the valence of element A, and - m is an integer ranging from 0 to v-1 , where n+m = v+1 O 99/35188 (2) The salts of oxoisothiochromanium having the following general formula: in which the R3 symbol represents a linear or branched alkyl radical containing from 1 to 20 carbon atoms; a linear or branched cycloalkyl radical containing from 1 to 20 carbon atoms, or an aryl radical. For example, the salts of oxoisothiochromanium that can be used are, in particular, the ones descπbed in patent application No. WO A90/11303 (published on October 4, 1990). The salts of oxoisothiochromanium that are particularly well suited include, in particular, the sulfonium salt of 2-ethyl-4-oxoιsothiochromanιum or of 2-dodecyl-4-oxoisothiochromanium. The anionic entity of the said onium salt is selected from among the group consisting of SbFs * . PF 6 .AsF 6 ", CF3SO3-, BF4-.BCI4-. B(0 3 SCF 3 ) 4 -, B(0 3 SC 2 F5)4-, and B(0 3 SC Fg)4-. However, other anionic entities may also be used, such as the ones descπbed in patent application No. EP-A 697449 (page 4, lines 28 to 37). Furthermore, in the case of a anionic entity consisting of borate, the said entity may be selected from among the group consisting of entities having the general formula [B X a ( 4)fc>]" (II), which also includes BF4 * and BCI4', and in which: a is an integer between 0 and 4, b is an integer between 0 and 4, with a + b = 4, - T e X symbols represent: • a halogen atom, preferably a chlorine or fluorine atom; or - an -OH function, with a = 0 to 2, The R4 symbols are either the same or different, and represent: - a phenyl radical substituted by at least one electron-attractor group, preferably CF 3 OCF3, NO2, or CN, or by at least 2 halogen atoms, preferably fluoπne atoms; - an aryl radical containing at least two aromatic nngs, such as diphenyl or naphthyf, optionally substituted by at least one element or one electron-attractor group, preferably CF3, NO2, or CN, or a halogen atom, particularly a fluoπne atom. The anionic entity that consists of a borate is advantageously selected from among the following anions- [B (C 6 F 5 ) 4 ]- [B (C 6 H 4 CF 3 ) 4 ]- [B( C 6 H 3 (CF 3 ) 2 ) 4 _- [(C 6 F 5 ) 2 B F 2 ]- [B (C 6 H 4 OCF 3 ) 4 ]" [B (C 6 H 3 F 2 ) 4 ]-. The onium salts having the general formula (I) are descπbed in many documents, particularly in the following patents: No. US-A-4 026 705, No. US-A-4 069 056, No. US-A-4 136 102, and No. US-A-4 173 476 In particular, the following cations are employed within the context of the invention: KΦ) 2 If [C 8 H 17 -0-φ- l -φf [C 12 H 2 5-Φ- I -Φ] + [(C 8 H 17 -0-φ) 2 l]+ KΦ) 3 S] + [(φ) 2 -S-φ-0-C 8 H 17 ] + [-φS-φ-S-(φ) 2 ] + [(Cι 2 H25-Φ)2 lI + [CH 3 -φ-l-φ-CH(CH 3 ) 2 ] + [CH 3 -φ-l-φ-CH 3 ] + and [(φ) 2 S-φ-S-φ-S(φ) 2 ] +2 The initiators that are employed in accordance with the invention advantageously consist of the following onium borates: [(Φ-CH 3 ) 2 l] + [B (C 6 F 5 )4]-. KΦ) 2 '] + [B (C 6 F 5 ) 4 ]-, [Ci2H25-Φ- l φ-] + [B (C 6 F 5 ) 4 ]-, [(C 8 H 17 -0-φ-l-φ] + [B (C 6 F 5 ) 4 ]- [(C 8 H 17 -0-φ)2 ll + [B (C 6 F 5 ) 4 ]-. KΦ)2 '] + tB (C 6 H 3 (CF 3 ) 2 ) 4 ]-, [(φ) 2 S-φ-0-C 8 H 17 ] + [B (C 6 H 4 CF 3 ) 4 ]-, [(C 12 H25-φ)2l] + tB (C 6 F 5 )4]-, [CH3- -I-Φ- CH(CH 3 ) 2 ] + (B (C 6 F 5 ) 4 ]-, [(φ)3 S] + [B (C 6 F 5 ) 4 ]-. [CH 3 -φ-l-φ-CH(CH 3 ) 2 r [B (C 6 H 4 OCF 3 ) 4 ]- and 2[B(C 6 F 5 ) 4 ]-[(φ) 2 S-φ-S-φ-S(φ)2] +2 wherein φ in the above formulas represents a phenyl radical. The onium borates used in the compositions in accordance with the present invention may be prepared by means of an exchange reaction between a salt of the cationic entity with a salt of an alkaline metal (for example, sodium, lithium, or potassium) of the anionic entity. The salt of the cationic entity may, for example, be a halide, such as a chloπde or an iodide, while the alkaline metal of the salt of the anionic entity may be sodium, lithium, or potassium The operating conditions (i.e., the respective quantities of the reagents, the selection of the solvents, the duration, the temperature, and the presence or absence of stirπng) are known and within the capabilities of those skilled in the art. The said conditions should allow the desired initiator salt to be recovered in solid form, through filtration of the precipitate that is formed, or else in the form of an oil, through extraction with an appropπate solvent. The alkaline metal salts of the anionic entity may be prepared in accordance with known procedures, through an exchange reaction between a halogen-boratβ compound and an organometallic compound (such as a magnesium, lithium, or tin compound) that contains the desired hydrocarbon groups in stoichiometπc quantities. The said reaction may optionally be followed by hydrolysis, with the aid of an aqueous solution of the halide of the alkaline metal. This type of synthesis is descπbed, for example, in J. of Organometallic Chemistry, Vol. 178 (1979), pp. 1-4; J.A.C.S., Vol. 82 (1960), p. 5298; Anal. Chβm. Ada, Vol. 44 (1969), pp. 175- 183; patents No. US-A-4 139 681 and No. DE-A-2 901 367; and Zh. Org. Khim., Vol. 25, No. 5 (May 1989), pp.1099-1102. The photoinitiator compound is usually in the form of a solid (i.e., a powder), and when used is usually in the form of a solution in a solvent or diluent. The proportions, by weight, between the photoinitiator or -initiators, on the one hand, and the solvent, on the other hand, are between 0 1 and 99 parts for every 100 parts of solvent, and preferably from 10 to 50 parts. The solvents that can be utilized for the photoinitiator are extremely numerous and vaned, and are selected in accordance with the photoinitiator that is used and in accordance with the other constituents of the composition in accordance with the invention. Generally speaking, the solvents may be alcohols, esters, ethers, ketones, chlonnated compounds, or nitriles. Alcohols that may be selected include isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, methyl isobutyl carbinol, diacetone alcohol, 2-ethylhexanol, para-tolyl-ethanol, isopropyl benzyl alcohol, benzyl alcohol, methanol and ethanol The commonly used ethers are 2-methoxy ethanol, 2- ethoxy ethanol, diethylene glycol and polyethylene glycol 200 The customary esters are dibutyl maleate, dimethyi-ethylmalonate, methyl saltcylate, dioctyl adipate, butyl tartrate, ethyl lactate. n-butyl lactate, and isopropyl lactate Other solvents that can be used for the photoinitiator bathr and that fall into the other categoπes of solvents mentioned heremabove include acetonitπle, benzonitπle, acetone, cyclohexanone, tetrahydrofuran, dichloromethane, and chlorobenzene Of the above mentioned solvents/diluents, the use of diacetone alcohol is particularly preferred. Furthermore, among the solvents that can be used to solubiiize the photoιnιtιator(s), certain types of organic solvents that donate protons and that have an aromatic structure, as well as certain types of hydroxylated carboxylic acid esters, are capable not only of solubiliziπg the photoinitiators but also of significantly improving their performance, in terms of reactivity and kinetics These types of solvents, which are known as "reactive diluents", are descπbed hereinbelow, and are advantageously utilized as a solvent for the photoιnιtιator(s) The type of solvent in which the photoinitiator is preferably solubiiized is selected from among the hydroxylated carboxylic acid esters that are liquid at room temperature (23 * C) and that have the following general formula (IV) OH R 5 -CH-CO-0-R 6 (| ) in which - The R5 and R5 symbols are either identical or different, and represent - a linear or branched alkyl radical that has from 1 to 10 carbon atoms and may optionally be substituted by a linear or branched alkoxy group that has from 1 to 4 carbon atoms; - a cycloalkyl radical that has from 4 to 10 carbon atoms and may optionally be substituted by one or more linear or branched alkyl or alkoxy groups that have from 1 to 4 carbon atoms; - an aryl radical that has from 5 to 12 carbon atoms and may optiona'iy be substituted by one or more linear or branched alkyl or alkoxy groups that have from 1 to 4 carbon atoms; and/or - an aralkyl or aroxyalkyl radical in which the aryl portion is a group that has from 5 to 12 carbon atoms and that may optionally be substituted by one or more linear or branched alkyl or alkoxy groups that have from 1 to 4 carbon atoms, and the alkyl portion is a linear or branched group that has from 1 to 4 carbon atoms - The R5 symbol may also represent- - a linear or branched alkoxy radical that has from 1 to 15 carbon atoms, and/or - a cycloalkyloxy radical that has from 4 to 10 carbon atoms and that may optionally be substituted by one or more linear or branched alkyl or alkoxy groups that have from 1 to 4 carbon atoms When used as solvents, these hydroxylated carboxylic acid esters possess properties that enable a significant improvement in the reactive and kinetic performance of the photoinitiators, and also in the final properties of the crosslinked coatings obtained. Specifically, the most worthwhile results are obtained with this type of solvent, which is formed by at least one hydroxylated carboxylic acid ester that has the general formula (IV), in which: - R5 represents a linear alkyl radical that has from 1 to 3 carbon atoms, and - Rg represents a linear or branched alkyl radical that has from 2 to 6 carbon atoms. More preferentially, the solvent utilized is formed by at least one ester of the lactic acid that has the general formula (IV) in which R, represents a methyl radical and R« represents a linear alkyl radical that has from 1 to 10 carbon atoms, for example any of the following radicals: methyl, ethyl, isopropyl, n-butyl, isobutyl, amyl, and octyl. In this case, the proportions, by weight, of the photoinitiators are from 10 to 50 parts for every 100 parts of solvent. This preferred family of solvents also has the advantages of being very economical, not particularly toxic, easy to handle, and compatible with the known initiator salts. The other component of the inventive composition compπses at least one amine which functions as a stabilizing agent The amine preferably has a boiling point is greater than 150'C and preferably greater than 200"C. The said amine may be a secondary or tertiary amine Amines that can be used in the compositions in accordance with the invention include: (1 ) A secondary or tertiary amine that has the following general formula (VIII)- y R n (VIII) in which Rg, R-J Q- and R11 are identical and/or different, and are selected from among the group consisting of: a linear or branched monovaleπt alkyl, alkoxy, or alkylene radical that contains from 1 to 12 carbon atoms, and that may contain and/or be substituted by at least one heteroatom, preferably an oxygen, sulfur, or nitrogen atom (for example, in order to form a reactive function such as an epoxy, ketone, or hydroxyl group); a monovalent cycloaikyl radical that contains between 3 and 9 carbon atoms, and that may contain and/or be substituted by at least one heteroatom, preferably an oxygen, sulfur, or nitrogen atom (for example, in order to form a reactive function such as an epoxy, ketone, or hydroxyl group); and a hydrogen radical. (2) Steπcally arranged cyclic amines that have the following general formula (IX): in which: - R12 corresponds to Rg, R' and R" are identical or different, and correspond to linear or branched alkyl radicals that contains from 1 to 12 carbon atoms, and that may contain and/or be substituted by at least one heteroatom, preferably an oxygen, sulfur, or nitrogen atom (for example, in order to form a reactive function such as an epoxy, ketone, or hydroxyl group); U is a free valence or a methylene radical, and u is between 1 and 9, in order to form a ππg that can: - contain at least one heteroatom, preferably an oxygen, sulfur, or nitrogen atom, and/or - be substituted by at least one heteroatom or by a linear or branched alkyl radical that contains from 1 to 4 atoms, with the heteroatom preferably being an oxygen, sulfur, or nitrogen atom (for example, in order to form a reactive function such as an epoxy, ketone, or hydroxyl group). (3) Amines consisting of groups having the general formulas (VIII) and (IX), interconnected by at least one saturated or unsaturated organic radical, and at least a divalent R13 radical, which may contain and/or be substituted by a heteroatom. 9/35188 1 1 As non-limiting examples, the R-| 3 radical may be selected from among the following radicals: - linear or branched alkylene radicals that have from 2 to 18 carbon atoms; - alkylene-carboπyl radicals whose alkylene portion, which may be linear or branched, contains from 2 to 20 carbon atoms; - alkylene-cyclohexylene radicals whose alkylene portion, which may be linear or . branched, contains from 2 to 12 carbon atoms, and whose cyclohexyiene portion includes an -OH group and optionally 1 or 2 alkyl radicals that contain 1 to 4 carbon atoms; - radicals having the formula -R14 - O - R14, in which the R14 radicals, which may be identical or different, represent alkylene radicals having from 1 to 12 carbon atoms; - radicals having the formula -R14 - O - R14, in which the R14 radicals have the meanings indicated heremabove, and one or both of them are substituted by one or two -OH groups; - radicals having the formula - O -CO- R14, in which the R14 radical has the meaning indicated heremabove, - radicals having the formula -R14 - COO - R14, in which the R14 radicals have the meanings indicated heremabove, - radicals having the formula -R15 -O -R-ig - O-CO-Ris, in which the R15 and Rfg radicals, which may be identical or different, represent alkylene radicals having from 2 to 12 carbon atoms, and the Rfg radical is optionally substituted by an hydroxyl radical; - trivalent groups having the following formula: — (CH,) CH \co — where m represents a number from 2 to 20, or - trivalent groups having the following formula: where p represents a numbe from 2 to 20. The steπcally arranged amines in accordance with the compositions in accordance with the invention include, at α in the nitrogen atom, alkyl groups that contain from 1 to 4 carbon atoms, and preferably methyl groups. In accordance with another preferred embodiment of the invention, the steπcally arranged amines contain pipeπdino groups. It should be noted that the majoπty of the steπcally arranged amines used as light-stability agents, particularly those having hindered amines (i.e., those of the "HALS" type) have been shown to be excellent candidates for meeting the requirements for the stabilizers used within the context of the invention, even though their intπnsic property of stability in the presence of light has no direct relationship with the action mechanism of the stabilizing ammo agents for the compositions in accordance with the invention. In this regard, vanous types of spatially arranged amines may be used, such as the ones described in EP 162 524 and No. EP 263 561. To the extent necessary for completion, the disclosures of these references are expressly incorporated by reference. Many types of spatially arranged amines that are commercially available in the mdustπal field have provided good results. These amines include: - The TINUVIN products sold commercially by the CIBA GEIGY company, and particularly the products known as TINUVIN 144 and TINUVIN 292, which have the general formulas (X) and (XI) respectively; - The CYAGARD products sold commercially by CYTEC, and particularly the product known as CYAGARD UV 1164L; and - The SANDUVAR products, and particularly the product known as SANDUVAR 3055, which has the general formula (XII) and which is sold commercially by the SANDOZ company. O 99/35188 13 Of the above commercially available mateπals, the TINUVIN 292 compound is particularly preferred. Other types of amines that have the general formulas (VIII) and (IX) are also good candidates for use in the compositions in accordance with the invention. As an example, the structure of some of these amines is given below: CH 3 -N -] H, — ' — Si(C€t), (XIII) (XIV) (XV) (EtO Si — ' \— W NUH NH, (XVI) The percentage of the amino agent generally used, by weight in relation to the total weight of the photoinitiator compound (exclusive of any diluent), is between 0.2 and 0.8 percent by weight of photoinitiator solids and preferably between 0.3 and 0.7 weight percent. In the case of the HALS-type ammo agent, the quantity is on the order of 0.4 to 0.6 weight percent. The photoinitiator composition is used to initiate polymeπzation of one or more compounds or compositions which contains one or more functional groups which are crossiinkable or polymeπzable through cationic crosslinking or polymeπzation . In practice, initiation occurs by exposing the photoinitiator to actinic radiation, which in turn, causes the release of one or more cations from the photoinitiator. The term "actinic radiation" is defined to mean any type of radiation which enables the liberation of cations from the photoinitiator. In practice, ultraviolet, visible light, infrared, electron beam or microwave radiation are particulariy preferred sources of radiation, which an ultraviolet source operating at a wavelength of between about 200 and about 400 nanometers being most preferred. In practice the compound or composition which contains one or more crossiinkable or polymenzable groups is either a polyorganosiioxane(s) having functional groups that can be crossiinked by cationic means or an ethylenically unsaturated compound or composition which is not a poiyorganosiloxane and which contains one or more epoxy groups. In practice the concentration of the photoinitiator or -initiators that is present is between 0.05 and 2% by weight in the said bath, and preferably between 0.2 and 0.6% of the entire composition (initiator composition, polymeπzable or crossiinkable compound/composition, and optional additives). in particulariy preferred embodiments, the compound/composition which contains one or more crossiinkable or polymeπzable groups is a poiyorganosiloxane, or mixture of polyorganosiloxanes. The polyorganosiioxanes that can be crossiinked by cationic means and that enter into the composition in accordance with the invention contain functional groups of the epoxy and/or vinyl ether type. The said polyorganosiloxanes are linear or essentially linear, consist of groups that have the general formula (V), and are terminated by groups that have the general formula (VI) or else are cyclic and consist of groups that have the general formula, as indicated below: R 7 R 7 -(-Si - O-)- (V) Y-Si-O- (VI) Y R 7 in which- - The R symbols are similar or different, and represent: - a linear or branched alkyl radical that contains from 1 to 8 carbon atoms and that may optionally be substituted by at least one halogen, preferably fluoπne, with the alkyl radicals preferably consisting of the methyl, ethyl, propyl, octyl, and 3,3,3- trifluoropropyl radicals; - a cycloalkyl radical containing between 5 and 8 cyclic carbon atoms, which may optionally be substituted as set forth above; - an aryl radical containing between 5 and 12 carbon atoms, which may be substituted as set forth above, and which preferably consists of phenyl or dichlorophenyl; or - an aralkyl radical that has an alkyl portion that contains between 5 and 4 carbon atoms and an aryl portion that contains between 5 and 12 carbon atoms, which may optionally be substituted, on the aryl portion, by halogens, alkyl radicals, and/or alkoxy radicals containing from 1 to 3 carbon atoms; - The Y symbols are similar or different, and represent: - the R 7 group, a hydrogen radical, and/or - an organofunctional group that can be crossiinked by cationic means, and preferably an epoxyfunctionai and/or vmyloxyfunctional group, linked to the silicon in the poiyorganosiloxane by means of a divalent radical that contains from 2 to 20 carbon atoms, and that can contain at least one hetero-atom, preferably an oxygen atom; and at least one of the Y symbols represents an organic functional group that can be crossiinked by cationic means. Preferably, at least one of the R symbols in the polyorganosiloxanes used in the compositions in accordance with the invention represents a phenyl, xylyl, tolyl, or dichlorophenyl radical. It is also advantageous for at least 60% (molar) of the R 7 radicals in the polyorganosiloxanes used in the compositions in accordance with the invention to be methyl radicals. In accordance with a preferred vaπant of the invention, from 1 to 50%, and preferably from 5 to 25% of the silicon atoms in the poiyorganosiloxane include one crossiinkable functional group. The epoxy functional Y groups are usually selected from among: c) -(CH 2 ),-0 CH 2 -CH— ^CH 2 ° and/or d) -(CH 2 ) 3 -0-CH -p CH O The functional groups preferably correspond to those of formula a). Furthermore, the vinyloxyfunctional Y groups are usually selected from among: - (CH 2 )3-0-CH=CH 2 - -0-(CH 2 )4-0-CH=CH2 and/or - CH 2 )3-0-R 8 -0-CH=CH 2 in which R 8 is: - a linear or branched alkylene radical that contains from 1 to 12 carbon atoms and that may be substituted as defined above: or - an aryleπe radical that contains from 5 to 12 carbon atoms and that is preferably phenylene and that may be substituted, preferably by from 1 to 3 alkyl groups that have from 1 to 6 carbon atoms More specifically, the polyorganosiloxanes used in the compositions in accordance with the invention have the following general formula (VII). in which - The R' symbols have the same meaning as the R 7 symbols mentioned heremabove for formulas (V) and (VI), and preferably, when R' is a linear or branched alkyl radical, it contains from 1 to 4 carbon atoms; - The X symbols are identical or different, and represent a monovalent radical selected from among the Y, H, and/or -OH radicals; - x is an integer or a fraction ranging from 20 to150, and preferably from 30 to 100; - t is an integer or a fraction ranging from 3 to 9, and preferably from 6 to 9; and - z is an integer or a fraction ranging from 0 to 5; and preferably from 0 .o 2. The epoxyfunctional polyorganosiloxanes can be prepared through an hydrosilylation reaction between oils with Si-H groups and epoxyfunctional compounds such as 1 ,2-epoxy-4-vιnyl- cyclohexane and allyl glycidyl ether The vmylfunctionai polyorganosiloxanes can be prepared through an hydrosilylation reaction between oils with Si-H groups and epoxyfunctional compounds such as allyl vinyl ether and allyl-v yloxy ethoxy benzene. The epoxyfunctional or vinyloxyfunctional polyorganosiloxanes used within the context of the invention are usually packaged in the form of fluids that have a dynamic viscosity of 10 to 10,000 mm 2 per second at a temperature of 25*C, and preferably a dynamic viscosity of 100 to 600 mm 2 per second at the said temperature The dynamic viscosity, at 25*C, of all of the siiicones considered in the present descπption can be measured with the aid of a BROOKFIELD viscometer, in accordance with AFNOR standard No 76-102 (February 1972) The compositions in accordance with the invention may also include other ingredients, such as adhesion modulators that make it possible to increase or reduce the adhesion forces obtained from the poiyorganosiloxane alone (e g., linear silicone resins or polymers that contain vinyl, epoxy, vinyl ether, or alcohol functions), pigments; photo-sensitizers; antrfungal, antibacteπal, and antimicrobial agents; corrosion inhibitors, etc. Preferred compounds or compositions which contain crossiinkable or polymenzable groups which are not based on silicone chemistry include the following: aliphatic and aromatic epoxy resins monomers and polymers The compositions in accordance with the invention which include the compound or composition containing crossiinkable or polymenzable groups are useful in the field of anti-adhesion coatings on cellulose mateπals, films, paint, the encapsulation or embedding of electπcal and electronic components, coatings for textile fabπcs, and for sheathing for optical fibers. They are particularly worthwhile when they are utilized in liquid form in order to render a mateπal (such as metal sheets or foils, glass, plastic mateπais, or paper) non-adhesive with regard to other mateπals to which it would otherwise normally adhere. The compositions in accordance with the invention advantageously display a degree of viscosity that does not exceed 5000 mPa/s, and that preferably does not exceed 4000 mPa/s at 25°C As a vanant, compositions may be preferred whose bath viscosity is between 200 and 1000 mPa/s at 25 β C. The invention also relates to a procedure that makes it possible to render the surface of a first article (for example, sheets) non-adhesive when in contact with the surface of a second article, in instances in which the surface of the said first article would normally adhere to the surface of the second article. The process for doing this involves the following steps: (1) providing a compound having polymenzable or crossiinkable groups; (2) adding to the compound a crosslinking or polymenzing effective amount of an initiator composition compnsmg: (a) a compound which liberates cations upon exposure to actinic radiation, and (b) a hindered amine stabilizer, (3) exposing the resulting composition to actinic radiation so that the initiator composition yields one or more cations, and (4) cationically polymeπzing or crosslinking the polymeπzable or crossiinkable groups. In preferred embodiments this procedure for the preparation of an article with a non-adhesive surface includes the following steps a) Applying a quantity of the composition in accordance with the invention, usually between 0 1 and 5 grams per square meter of the surface area of the said article; and b) then crosslinking the composition by applying energy, which is provided at least in part, and preferably entirely, by UV radiation The UV radiation that is utilized has a wavelength between 200 and 400 nanometers (nm) The duration of the irradiation stage may be bπef - generally less than 1 second - and may be on the order of a few hundredths of a second for very thin layers of compositions deposited onto the surfaces in question The crosslinking advantageously takes place without the application of any heat However, the invention does not exclude a step consisting of heating to a temperature between 25 and 100"C Furthermore, the hardening time can be regulated, particularly through the number of UV lamps utilized, through the duration of the exposure to UV radiation, and through the distance between the composition and the UV lamp The compositions that do not include a solvent (i e., the non-diluted cσmposιtι-ms) are applied with the aid of devices that are suitable for depositing, in a uniform manner, small quantities of the fluids onto a surface. For this purpose, one may for example use a "Heiio-glissant" device, which specifically consists of two supeπmposed cylinders The function of the lower cylinder, which is immersed in the coating receptacle that contains the composition, is to impregnate, in the form of a very thin layer, the upper cylinder, whose function is then to deposit onto the paper the desired quantities of the composition with which the said upper cylinder has been impregnated Such a quantification is obtained through the adjustment of the respective speed of the two cylinders, which rotate in opposite directions in relation to one another The quantities of the compositions deposited onto the substrates are vaπabie, in most cases ranging from 0 1 to 5 grams per square meter of the surface area treated These quantities depend on the nature of the substrates and on the desired anti-adhesion properties In most instances, the said quantities are between 0 5 and 3 grams per square meter for non-porous substrates The coated articles, mateπals, or substrates may subsequently be placed in contact with other adhesive mateπals, such as for example certain rubber or acrylic mateπals. After contact has been made through the application of pressure, the adhesive mateπals can easily be detached from the article that has been coated with the photo-crosslinked article. While not wishing to be bound to any particular scientific theory, the inventors have surpπsmgty discovered that the presence of the amine in combination with the photoinitiator provides a significant increase in the shelf-life of the initiator This is particularly pronounced when a diluent is associated with the initiator It is speculated that when a diluent is present, there may be a premature release of cations from the initiator, thereby reducing its efficacy and long-term stability as a result of increased acidity of the composition It is further believed that the amine functions to sequester any cations that are inadvertently released, thereby preventing degradation of the mateπal. In addition, when a diluent is present, by-products of the diluent could be formed which can potentially pose environmental and disposal problems. Again, while not wishing to be bound to any particular scientific theory, it is believed that such by-products do not form as a result of the amine/initiator/diluent interactions The invention is further descπbed in the following non-limiting examples Comparative Example 1 20 parts of tetrakis (pentafluorophenyl) borate tolylcumyliodonium having the following general formula: [CH3-Φ-I-Φ- CH(CH 3 ) 2 ] + [B (C 6 F 5 ) 4 )- are added to 80 parts of diacetone alcohol. The lodonium borate is prepared in accordance with the general procedure descπbed in European patent applications No. 562 922 and No 562 897 To the extent necessary for completion, the disclosures contained therein are expressly incorporated by reference. Example 2 To the composition of Comparative Example 1 is added 1000 parts per miilioπ of the compound commercially available as TINUVIN 292 from Ciba Geigy. Its chemical structure is believed to be shown in the following formula. Testing of Example Compositions (1) Aging Stability The respective compositions are tested for age stability by pH measurement over a period of time. Two storage conditions are utilized; one at 70°F, the other at 120°F. Maintaining as high of a pH as possible over the storage time period is a desired result. The results are shown in the attached tables. Values in the tables are pH units. (2) Presence of By-Products The diacetone alcohol diluent can generate and release mesityl oxide, an undesirable byproduct, into the photoinitiator solution over time. The percent of mesityl oxide present in the initiator after storage at both 70°F (storage for about 8 months) and 120°F (storage for about 5 7 months) is measured. The amount of mesityl oxide present in the initiator (percent by weight) after storage is shown in the following table. The above data suggests that the TINUVIN 292 hindered amine light stabilizer [HALS] effectively retards the gradual "acidification" of the cationic photoinitiator which results from the spontaneous degradation of the iσdonium-borate salt. It is believed that the TINUVIN 292 accomplishes this feat by helping maintain the pH neutrality of the lodonium-borate/di-acetone alcohol solution as well as acting as an efficient acidic hydrogen proton [H+] scavenger In addition, by retarding the "acidification" of the lodonium-borate/di-acetone alcohol solution, the TINUVIN 292 indirectly helps to prevent the "acid promoting" degradation of the di-acetone alcohol diluent which generates undesirable mesityl oxide. The composition of Example 2 is used to initiate polymenzation and/or crosslinking of a cationic reactive poiyorganosiloxane containing epoxy reactive groups which is ultimately used to form an anti-adherent coating The efficiency of the photinitiator of Example 2, even one which has been stored for over six months, exceeds that of comparative photoinitiators which do not contain the amine stabilizing agent This is presumably because of the stabilizer preventing in situ degradation of the photoinitiator composition over a penod of time. Having descπbed the invention in detail and by reference to the preferred embodiments thereof, it will be apparent that modifications and vaπations are possible without departing from the scope of the appended claims

Claims: WHAT IS CLAIMED IS. 1 A composition εompπs g (a) a compound which liberates cations upon exposure to actinic radiation, and (b) an amine stabilizer 2. The composition according to claim 1 wherein component (a) compπses: (1) at least one onium salt having a cationic portion of formula: [(Rl) n - A -(R2) m ] + (I) in which: - A represents an element selected from the group consisting of I, S, Se, P, and N; - R 1 represents a carbocyclic or heterocyciic aryl radical that has from 6 to 20 carbon atoms; - R 2 represents R 1 , an alkyl radical, or a linear or branched alkenyi radical containing from 1 to 30 carbon atoms; - n is an integer ranging from 1 to v+1 , where v is the valence of element A, and - m is an integer ranging from 0 to v-1 , where n+m = v+1 , or (2) one or more salts of oxoisothiochromanium of formula- wherein R 3 represents a linear or branched alkyl radical containing from 1 to 20 carbon atoms; a linear or branched cycloalkyi radical containing from 1 to 20 carbon atoms, or an aryl radical. The composition according to claim 2 wherein R 1 further contains nitrogen or sulfur heteroatoms 4 The composition according to claim 2 wherein R 1 or R 2 are substituted by an alkoxy group that contains from 1 to 25 carbon atoms, an alkyl group containing from 1 to 25 carbon atoms, a nitro group, a chloro group, a bromo group, a cyano group, a carboxyl group or a mercapto group. 5. The composition according to claim 1 wherein component (a) compnses at least one onium salt having an anionic portion wherein the anionic entity of the said onium salt is selected from the group consisting of SbFg-, BF4-, PFg-, CF3S0 3 -, B(0 3 SCF 3 )4-, B(0 3 SC 2 F 5 ) 4 -, and B(0 3 SC 4 F 9 ) . 6. The composition according to claim 1 wherein component (a) compπses at least one onium salt having an anionic portion of formula [B X a ( )bJ- (») in which: a is an integer between 0 and 3, b is an integer between 0 and 4, with a + b = 4, X represents: - a halogen atom, a = 0 to 3; or - an -OH function, with a = 0 to 2; R4 may be the same or different, and represents: - a phenyl radical substituted by at least one electron-attractor group; or - an aryl radical containing at least two aromatic rings. 7. The composition according to claim 1 wherein component (a) is selected from the group consisting of [(φ-CH 3 ) 2 l] + [B (C 6 F 5 ) 4 ]-, [(φ) 2 l] + [B ^5)4]-. [C 12 H 25 -Φ- I Φ-] + [B (C 6 F 5 )4l-, [(C 8 H 17 -0-φ-l-φ] + [B (C 6 F 5 ) 4 ]-, [(C 8 H 17 -0-φ)2 l] + [B (C 6 F 5 ) 4 1-. [(φ) 2 l] + [B (C 6 H 3 (CF 3 ) 2 ) 4 ]-. [(φ) 2 S-φ-0-C 8 H 17 ] + [B (C 6 H 4 CF 3 )4]-, [(C 12 H 2 5-Φ)2l] + [B (CgF 5 ) 4 ]-, (CH3-Φ-I-Φ- CH(CH 3 ) 2 ]+ [B (C 6 F 5 ) 4 ]-. [(φ)3 S] + [B (C F 5 ) 4 r. [CH 3 -φ-l-φ-CH(CH 3 ) 2 ] + [B (C 6 H 4 OCF 3 ) 4 ]-, and 2[B(C 6 F 5 )4]-[(φ) 2 S-φ-S-φ-S(φ)2] +2 wherein φ in the above formulas represents a phenyl radical 8 The composition according to claim 1 wherein component (b) is selected from the group consisting of- (1 ) A secondary or tertiary amine of formula (VIII) R " (VIII) in which Rg, Rι 0 , and R-j -j are identical and/or different, and are selected from the group consisting of: an unsubstituted or substituted linear or branched monovaient alkyl, alkoxy, or alkylene radical that contains from 1 to 12 carbon atoms; an unsubstituted or substituted monovaient cycloalkyi radical that contains between 3 and 9 carbon atoms; and a hydrogen radical; (2) a steπcally arranged cyclic amine of formula (IX): in which: Rl2 is selected from the group consisting of an unsubstituted or substituted linear or branched monovaient alkyl, alkoxy, or alkylene radical that contains from 1 to 12 carbon atoms; an unsubstituted or substituted monovaient cycloalkyi radical that contains between 3 and 9 carbon atoms; and a hydrogen radical; R' and R" are identical or different, and represent an unsubstituted or substituted linear or branched monovaient alkyl, alkoxy, or alkylene radical that contains from 1 to 12 carbon atoms; U is a free valence or a methylene radical, and u is between 1 and 9. in order to form a - contain at least one oxygen, sulfur, or nitrogen heteroatom, or - be substituted by at least one heteroatom or by a linear or branched alkyl radical that contains from 1 to 4 atoms; and an amine compπsed of groups having the general formulas (VIII) and (IX), interconnected by at least one saturated or unsaturated organic radical, and at least a divalent R13 radical selected from the group consisting of: - linear or branched alkylene radicals that have from 2 to 18 carbon atoms; • aikyiene-carbonyl radicals whose alkylene portion, which may be linear or branched, contains from 2 to 20 carbon atoms; - alkylene-cyciohexylene radicals whose alkylene portion, which may be linear or branched, contains from 2 to 12 carbon atoms, and whose cyclohexylene portion includes an -OH group; - radicals having the formula -R14 - 0 - R14, - O -CO- R-^ or -R14 - COO - R14 in which the R-1 radicals, which may be identical or different, represent alkylene radicals having from 1 to 12 carbon atoms; - radicals having the formula -R15 -O -R-jg - O-CO-Ris, in which the R15 and Ri radicals, which may be identical or different, represent alkylene radicals having from 2 to 12 carbon atoms; - trivalent groups of formula: CO — where m represents a number from 2 to 20, and - tπvalent groups of formula: where p represents a number 2 to 20. 9. The composition according to claim 8 wherein said amine is a stencally arranged amine that includes, at the α position to the nitrogen atom, alkyl groups that contain from 1 to 4 carbon atoms. 10. The composition according to claim 9 wherein said steπcally arranged amine is an amine that contains at least one pipendino group. 11. The composition according to claim 8 wherein said amine is selected from the group consisting of: 12 The composition according to claim 1 further compπsing a diluent. 13 The composition according to claim 12 wherein said diluent is selected from the group consisting of alcohols, esters, ethers, ketones, chlonnated compounds and nitπies 14 The composition according to claim 13 wherein said diluent is selected from the group consisting of isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, methyl isobutyl carbmol, diacetone alcohol, 2-ethyihexanol, para-tolyl-ethanol, isopropyl benzyl alcohol, benzyl alcohol, methanol, 'ethanol, 2-methoxy ethanol, 2-ethoxy ethanol, diethylene glycol, polyethylene glycol 200, dibutyl maleate, dimethyl-ethylmalonate, methyl salicylate, dioctyl adipate, butyl tartrate, ethyl lactate, n-butyl lactate, isopropyl lactate, acetonrtπle, benzonrtπle, acetone, cyclohexanone, tetrahydrofuran, dichloromethane, and chlorobβnzene 15 The composition according to claim 14 wherein said diluent compπses diacetone alcohol. 16 The composition according to claim 12 wherein said diluent is selected from the group consisting of (i) hydroxylated carboxylic acid esters of formula: OH 3 -CH-CO O-R 6 in which- - R5 represents: - a substituted or unsubstituted linear or branched alkyl radical that has from 1 to 10 carbon atoms; - a substituted or unsubstituted cycloalkyi radical that has from 4 to 10 carbon atoms; - a substituted or unsubstituted aryl radical that has from 5 to 12 carbon atoms; - an aralkyl or aroxyalkyl radical in which the aryl portion is a substituted or unsubstituted aryl group that has from 5 to 12 carbon atoms, and the alkyl portion is a linear or branched group that has from 1 to 4 carbon atoms; or - a linear or branched alkoxy radical that has from 1 to 15 carbon atoms, and Rg represents: - a substituted or unsubstituted linear or branched alkyl radical that has from 1 to 10 carbon atoms; - a substituted or unsubstituted cycloalkyi radical that has from 4 to 10 carbon atoms; - a substituted or unsubstituted aryl radical that has from 5 to 12 carbon atoms; or an aralkyl or aroxyalkyl radical in which the aryl portion is a substituted or unsubstituted aryl group that has from 5 to 12 carbon atoms, and the alkyl portion is a linear or branched group that has from 1 to 4 carbon atoms. 17 A composition of matter consisting essentially of a mixture of: [CH3-Φ-I-Φ- CH(CH 3 ) 2 ] + [B (C 6 F 5 ) r; diacetone alcohol. 18. A process for polymerizing or crosslinking a composition comprising the steps of: (1) providing a compound or composition having polymenzable or crossiinkable groups; (2) adding to the compound or composition a crosslinking or polymerizing effective amount of an initiator composition compπsing: (a) a compound which liberates cations upon exposure to actinic radiation; and (b) an amine stabilizer (3) exposing the resulting composition to actinic radiation so that the initiator composition yields one or more cations; and (4) catioπically polymerizing or crosslinking the polymeπzable or crossiinkable groups. 19. The process according to claim 18 wherein said compound having polymenzable or crossiinkable groups is selected from the group consisting of polyorganosiloxanes having functional groups that can be crossiinked by cationic means; and ethylenically unsaturated compounds or compositions which are not polyorganosiloxanes and contain one or more epoxy groups. 20 The process accord i ng to cla i m 19 wherein said actinic radiation compπses ultraviolet radiation.

Inventors: BEATY REESHEMAH L, KERR STUART R III, BEATY, REESHEMAH, L., KERR, STUART, R., III
Applicants: RHODIA, RHODIA INC.
Application year: 1998
Main classification: C08K5
IPC codes: C08F2, C08G59, C08K5, C09D183