Cationically curable silicone compositions based on colloidal silica and anti-mist/anti-fouling hard coatings formed therefrom

Abstract

Silicone compositions that are cationically crosslinkable into hard, anti-mist/anti-fouling coatings, e.g., onto thermoplastic substrates, contain colloidal particles of non-functionalized silica and also: at least one crosslinkable and/or polymerizable silicone monomer, oligomer and/or polymer comprising: at least one structural unit of formula (I): Z 1 (R 0 ) a SiO (3−a)/2   (I) in which: a=0, 1 or 2; the radicals R 0 , which may be identical or different when a >1, are each an alkyl, cycloalkyl, aryl, vinyl, or alkoxy radical, or a hydrogen atom; the radicals Z 1 , which may be identical or different when the number of units of formula (I) is greater than 1, are each an organic substituent comprising at least one epoxy and/or alkenyl ether and/or oxetane and/or dioxolane and/or carbonate reactive functional group; and a total number of silicon atoms per molecule at least equal to 2; and an effective amount of at least one cationic initiator; and optionally, at least one organic solvent.

1 . A silicone composition cationically crosslinkable into a hard coating, comprising colloidal particles of non-functionalized silica and which additionally comprises: 
 at least one crosslinkable and/or polymerizable silicone monomer, oligomer and/or polymer comprising:    at least one structural unit of formula (I):      Z 1 (R 0 ) a SiO (3−a)/2   (I)    in which:    a=0, 1 or 2;    the radicals R 0 , which may be identical or different when a>1, are each an alkyl, cycloalkyl, aryl, vinyl, or alkoxy radical, or a hydrogen atom;    the radicals Z 1 , which may be identical or different when the number of units of formula (I) is greater than 1, are each an organic substituent comprising at least one epoxy and/or alkenyl ether and/or oxetane and/or dioxolane and/or carbonate reactive functional group; 
 and a total number of silicon atoms per molecule at least equal to 2; and  
 an effective amount of at least one cationic initiator; and  
 optionally, at least one organic solvent.  
   
   
   
       2 . The silicone composition as defined by  claim 1 , further comprising, as anti-mist compound, at least one crosslinkable and/or polymerizable silicone monomer, oligomer and/or polymer comprising at least one structural unit of formula (II):  
       Z 2 (R 0 ) a SiO (3−a)/2   (II)  
     in which: 
 a=0, 1 or 2;  
 R 0  is as defined above;  
 the radicals Z 2 , which may be identical or different when the number of units of formula (II) is greater than 1, is an organic substituent comprising at least one oxyalkyl or polyoxyalkyl functional group ((CH 2 ) m O) x  or (CH 2 —CH(CH 3 )—O) y  or copolymers, said monomer, oligomer and/or polymer exhibiting a viscosity of less than 500 mPa·s.  
 
   
   
       3 . The silicone composition as defined by  claim 1 , further comprising, as anti-fouling compound, at least one crosslinkable and/or polymerizable silicone monomer, oligomer and/or polymer comprising at least one structural unit of formula (III):  
       Z 3 (R 0 ) a SiO (3−a)/2   (III)  
     in which: 
 a=0, 1 or 2;  
 the radicals R 0 , which may identical or different, are each an alkyl, cycloalkyl, aryl, vinyl, or alkoxy radical, or a hydrogen atom;  
 the radicals Z 3 , which may be identical or different when the number of units of formula (III) is greater than 1, are each an organic substituent comprising at least one (C n F 2n+1 )—(R 0 ) a  group with n<20, and/or one perfluoropolyether compound of formula (IV):  
   Y—(C a F 2a O) b —C a F 2a —Y  (IV)  
 in which:  
 Y is a polymerizable group;  
 a ranges from 1 to 7;  
 b ranges from 1 to 300, such that said perfluoropolyether compound has an average molecular mass of from 500 to 20,000.  
 
   
   
       4 . The silicone composition as defined by  claim 2 , further comprising, as anti-fouling compound, at least one crosslinkable and/or polymerizable silicone monomer, oligomer and/or polymer comprising at least one structural unit of formula (III):  
       Z 3 (R 0 ) a SiO (3−a)/2   (III)  
     in which: 
 a=0, 1 or 2;  
 the radicals R 0 , which may identical or different, are each an alkyl, cycloalkyl, aryl, vinyl, or alkoxy radical, or a hydrogen atom;  
 the radicals Z 3 , which may be identical or different when the number of units of formula (III) is greater than 1, are each an organic substituent comprising at least one (C n F 2n+1 )—(R 0 ) a  group with n<20, and/or one perfluoropolyether compound of formula (IV):  
   Y—(C a F 2a O) b —C a F 2a —Y  (IV)  
 in which:  
 Y is a polymerizable group;  
 a ranges from 1 to 7;  
 b ranges from 1 to 300, such that said perfluoropolyether compound has an average molecular mass of from 500 to 20,000.  
 
   
   
       5 . The silicone composition as defined by  claim 1 , said at least one cationic initiator comprising a cationic moiety selected from among onium ions of formula (V):  
       [(R 1 ) n -A-(R 2 ) m ] +   (V)  
     in which: 
 A is an element from Groups 15 to 17 of the Periodic Table;  
 R 1  is a C 6 -C 20  carbocyclic or heterocyclic aryl radical, said heterocyclic radical optionally comprising nitrogen or sulfur as heteroelements' 
 R 2  is R 1  or a linear or branched C 1 -C 30  alkyl or alkenyl radical, said R 1  and R 2  radicals optionally being substituted by a C 1 -C 25  alkoxy, C 1 -C 25  alkyl, nitro, chloro, bromo, cyano, carboxyl, ester or mercapto group;  
 n is an integer ranging from 1 to v+1, v being the valency of the element A;  
 m is an integer ranging from o to v−1, with n+m=v+1.  
 
   
   
       6 . The silicone composition as defined by  claim 5 , the anionic moiety of the initiator comprising a borate of formula (VI):  
       [BX a R b ] −   (VI)  
     in which: 
 a and b are integers ranging, for a, from 0 to 3 and, for b, from 1 to 4, with a+b=4;  
 the X symbols are each:  
 a halogen atom, with a=0 to 3,  
 an OH functional group with a=0 to 2;  
 the R symbols, which are identical or different, are each: 
 a phenyl radical substituted by at least one electron-withdrawing group, and/or by at least 2 halogen atoms when the cationic moiety is an onium of an element from Groups 15 to 17 of the Periodic Table,  
 a phenyl radical substituted by at least one electron-withdrawing element or group, when the cationic moiety is an organometallic complex of an element from Groups 4 to 10 of the Periodic Table, or  
 an aryl radical comprising at least two aromatic rings, optionally substituted by at least one electron-withdrawing element or group whatever the cationic moiety.  
 
 
   
   
       7 . The silicone composition as defined by  claim 1 , said at least one initiator being selected from the group consisting of: 
 [(C 8 H 17 )—O-Φ-I-Φ] +  [B(C 6 F 5 ) 4 ] − , [(CH 3 ) 2 —-Φ-I-Φ-CH 3 ] +  [B(C 6 F 5 ) 4 ] −     [C 12 H 25 -Φ-I-Φ] +  [B(C 6 F 5 ) 4 ] − , [(C 8 H 17 —O-Φ) 2 I] +  [B(C 6 F 5 ) 4 ] −     [(C 8 H 17 )—O-Φ-I-Φ] +  [B(C 6 F 5 ) 4 ] − , [(Φ) 3 S] +  [B(C 6 F 5 ) 4 ] −     [(Φ) 2 S-Φ-O—C 8 H 17 ] +  [B(C 6 H 4 CF 3 ) 4 ] − , [(C 12 H 25 -Φ) 2 I] +  [B(C 6 F 5 ) 4 ] −     [(CH 3 ) 2 —CH-Φ-I-Φ-CH 3   +  [B(C 6 H 3 (CF 3 ) 2 ) 4 ] −     (η 5 -cyclopentadienyl)(η 6 -toluene)Fe +  [B(C 6 F 5 ) 4 ] −     (η 5 -cyclopentadienyl)(η 6 -1-methylnaphthalene)Fe +  [B(C 6 F 5 ) 4 ] − 
 (η 5 -cyclopentadienyl)(η 6 -cumene)Fe +  [B(C 6 F 5 ) 4 ] −   
   
   
   
       8 . The silicone composition as defined by  claim 1 , said at least one cationic initiator comprising a nontoxic onium salt having a cationic structure of formula (VII):  
       [(CH(CH 3 ) 2 -Φ-)-I—(—R 1 )] +   (VII)  
     in which R 1  is the -Φ-R 2  radical, R 2  being a linear or branched alkyl radical having from 1 to 20 carbon atoms.  
   
   
       9 . The silicone composition as defined by  claim 8 , the anionic structure of the onium salt being selected from the group consisting of: Cl − , Br − , BF 4   − , PF 6   − , CF 3 SO 3   − , N(SO 2 CF 3 ) 2   − , CH(SO 2 CF 3 ) 2   − , B(C 6 F 5 ) 4   − , B(PhOCF 3 ) 4   − , SbF 6   − and/or AsF 6   − .  
   
   
       10 . The silicone composition as defined by  claim 1 , comprising a silicone oligomer having the following formula (VIII):  
       Z 4 Si(R 0 ) a O (3−a)/2   (VIII)  
     in which: 
 a=0, 1 or 2;  
 the radicals R 0 , which may be identical or different, are each an alkyl, cycloakyl, aryl, vinyl, or alkoxy radical, or a hydrogen atom;  
 Z 4  is selected from among the following radicals:  
                                       
 
   
   
       11 . The silicone composition as defined by  claim 3 , wherein Z 3  is a perfluoropolyether compound selected from the group consisting of: 
 (C 2 H 5 O) 2 CH 3 SiC 3 H 6 NHCO(CF 2 O) 15 (C 2 F 4 O) 13 CF 2 CONHC 3 H 6 SiCH 3 (OC 2 H 5 ) 2 ,    (C 2 H 5 O) 3 SiC 3 H 6 NHCO(CF 2 O) 15 (C 2 F 4 O) 13 CF 2 CONHC 3 H 6 Si(OC 2 H 5 ) 3 ,    F(CF(CF 3 )CF 2 O) 25 CF 2 CF 3 , C 4 H 9 NHCO(CF 2 O) 15 (C 2 F 4 O) 13 CF 2 CONHC 4 H 9 ,    CH 2 ═CHCOO 2 H 4 NHCO(CF 2 O) 15 (C 2 F 4 O) 13 CF 2 CONHC 2 H 4 OOCCH═CH 2 ,    (HOCH 2 ) 2 CH 2 NHCO(CF 2 O) 15 (C 2 F 4 O) 13 CF 2 CONHCH 2 (CH 2 OH) 2 ,    (C 2 H 5 O) 3 Si(CH 2 ) 3 NHCO(CF 2 CF 2 O) 8 CF 2 CONH(CH 2 ) 3 Si(OC 2 H 5 ) 3 ,    (C 2 H 5 O) 2 CH 3 Si(CH 2 ) 3 NHCO(CF 2 CF 2 O)CF 2 CONH(CH 2 ) 3 SiCH 3 (OC 2 H 5 ) 2 ,    (C 2 H 5 O) 2 CH 3 Si(CH 2 ) 3 NHCO(CF 2 CF 2 O) 14 CF 2 CONH(CH 2 ) 3 SiCH 3 (OC 2 H 5 ) 2 ,    (C 2 H 5 O) 3 Si(CH 2 ) 3 NHCO(CF 2 C(CF 3 )FO) 12 CF 2 CONH(CH 2 ) 3 Si(OC 2 H 5 ) 3 ,    (C 2 H 5 O) 2 CH 3 Si(CH 2 ) 3 NHCO(CF 2 C(CF 3 )FO) 12 CF 2 CONH(CH 2 ) 3 SiCH 3 (OC 2 H 5 ) 2  or    OOCCH═CF 2  OOCCH 2      H 2 ═HCCOO—CH 2 CHCH 2 NHCO(CF 2 O) 15 (CF 2 CF 2 O) 13 CF 2 CONHCH 2 CHCH 2 —OOCCH═CH 2      
   
   
       12 . The silicone composition as defined by  claim 1 , said silica particles having a mean diameter of less than 1 μm  
   
   
       13 . The silicone composition as defined by  claim 1 , comprising an alcoholic solvent.  
   
   
       14 . The silicone composition as defined by  claim 13 , the proportion of organic solvent being at least equal to 10 parts by weight.  
   
   
       15 . The silicone composition as defined by  claim 1 , in crosslinked state.  
   
   
       16 . A substrate having a hard, anti-mist/anti-fouling coating of the silicone composition as defined by  claim 15 .  
   
   
       17 . A thermoplastic substrate having a hard, anti-mist/anti-fouling coating of the silicone composition as defined by  claim 15.