Polymerization catalyst for polythiourethanes, polymerizable liquid composition and process for the production of organic polythiourethane glass with a high refractive index

Abstract

Polymerization catalysts for organic polythiourethane glass which do not contain organometallic compounds contain a mixture of a tertiary aliphatic amine and a disubstituted phosphoric acid in a molar ratio ranging from 1/1.3 to 1/20. Polymerizable liquid compositions containing three components (A), (B) and (C) are also provided, wherein component (A) contains at least one cycloaliphatic diisocyanate monomer wherein the weight percentage of free isocyanate groups in component (A) ranges from about 20% to about 50% by weight with respect to the total weight of component (A); component (B) contains at least one polythiol having a molecular weight ranging from 50 to 1,200 g/moles and a functionality ranging from 2 to 5, said components (A) and (B) being present in a weight ratio varying from 0.5:1 to 2:1; and component (C) being said polymerization catalyst. A process for the production of organic glass using the polymerizable liquid composition is further provided.

1 . A polymerization catalyst for organic polythiourethane glass, wherein the catalyst does not contain organometallic compounds and consists of a mixture of
 a tertiary amine represented by the following general formula (1):   
       
         
           
           
               
               
           
         
         wherein: 
         R1, R2 and R3, equal to or different from each other, represent a C 1 -C 20  linear or branched aliphatic group, or a C 3 -C 20  cycloaliphatic group, said groups possibly optionally containing heteroatoms selected from the group consisting of N, O, P, S, and halogens; and
 a disubstituted phosphoric acid having general formula (2): 
 
       
       
         
           
           
               
               
           
         
         wherein: 
         R2 and R4, equal to or different from each other, represent a linear or branched C 1 -C 20  aliphatic group, or a C 3 -C 20  cycloaliphatic group; 
         R3 and R5, the same or different, represent a C 1 -C 3  alkylidene group and m and p are equal to 0, 1 or 2; and 
         the tertiary aliphatic amine and the disubstituted phosphoric acid being present in a molar ratio ranging from 1/1.3 to 1/20. 
       
     
     
         2 . The catalyst according to  claim 1 , wherein the aliphatic amine is selected from triethylamine, tri-n-propylamine, tri-isopropylamine, and mixtures of methyl-1,2,2,6,6-pentamethyl-4 piperidinyl sebacate and bis(1,2,2,6,6-pentamethyl-4 piperidinyl)sebacate. 
     
     
         3 . The catalyst according to  claim 1 , wherein the disubstituted phosphoric acid is selected from bis(2-ethylhexyl)phosphate, C 8  diester of phosphoric acid, C 10  diester of phosphoric acid and/or mixtures thereof. 
     
     
         4 . The catalyst according to  claim 1 , consists of mixtures of triethylamine and bis(2-ethylhexyl)phosphate or mixtures of methyl-1,2,2,6,6-pentamethyl-4 piperidinyl sebacate and bis(1,2,2,6,6-pentamethyl-4 piperidinyl)sebacate with bis(2-ethylhexyl)phosphate. 
     
     
         5 . A polymerizable liquid composition of polythiourethane comprising three components (A), (B), and (C), wherein component (A) contains at least one cycloaliphatic diisocyanate monomer in which the weight percentage of free isocyanate groups in said component (A) ranges from about 20% to about 50% by weight with respect to the total weight of component (A); component (B) contains at least one polythiol, having a molecular weight varying from 50 to 1,200 g/mole and a functionality varying from 2 to 5, said components (A) and (B) being present in a weight ratio varying from 0.5:1 to 2:1; component (C) being a catalyst according to  claim 1 . 
     
     
         6 . The polymerizable composition according to  claim 5 , wherein component (A) is selected from 4,4′-methylene bis(cyclohexyl isocyanate) and bis(isocyanate methyl)cyclohexane. 
     
     
         7 . The polymerizable composition according to  claim 5 , wherein component (B) is selected from polythiols having general formula (3): 
       
         
           
           
               
               
           
         
         wherein: 
         R represents alkylidene groups having from 1 to 6 carbon atoms, the same or different; R1 represents alkyl groups having from 1 to 10 carbon atoms, the same or different; n ranges from 1 to 6; m varies from 1 to 6; p varies from 1 to 4; q is equal to 0 or 1 and p+q is equal to 4; and 
         polythiols having general formula (4): 
       
       
         
           
           
               
               
           
         
         wherein: 
         R represents an alkylidene group having from 1 to 6 carbon atoms; n ranges from 1 to 6; m ranges from 1 to 6; and/or polythiols having general formula (5): 
       
       
         
           
           
               
               
           
         
         wherein: 
         R1=—(CH 2 ) n —SH; R2=—S—(CH 2 ) n —SH; R3=—R—S—(CH 2 ) n —SH; R is an alkyl group having from 1 to 10 carbon atoms and n ranges from 1 to 3. 
       
     
     
         8 . The polymerizable composition according to  claim 5 , wherein component (B) is selected from 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol and a mixture of 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol and ethylene glycol-di(3-mercaptopropionate). 
     
     
         9 . The polymerizable composition according to  claim 5 , wherein component (A) is a mixture of 4,4′-methylene bis(cyclohexyl isocyanate) and ethylene glycol-di(3-mercaptopropionate), and component (B) is 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol. 
     
     
         10 . The polymerizable composition according to  claim 5 , wherein the quantity of component (C) ranges from 0.1 to 2% by weight with respect to the total weight of the polymerizable composition. 
     
     
         11 . A process for the production of organic glass which provides a casting and polymerization process of a polymerizable liquid composition of polyurethane, according to  claim 5 , comprising the following phases:
 a mixing phase a) of components (A) and (C);   a mixing phase b) of the solution obtained in the mixing phase a) and component (B), optionally in the presence of other additives;   a filtration phase c) to remove any pollutants dispersed in the mixture, said filtration phase also being effected alternatively or additionally, on the single components (A) and (B) before the mixing phase b);   a filling phase d) of a mould, wherein the mixture obtained at the end of phase c) is placed inside the mould; and   a polymerization phase e) wherein the liquid composition placed in the mould, is polymerized by thermal treatment.   
     
     
         12 . Organic glass obtained by the process according to  claim 11 . 
     
     
         13 . Manufactured products or optical articles obtained by the processing of the organic glass according to  claim 12 . 
     
     
         14 . Manufactured products or optical articles according to  claim 13 , selected from the group consisting of ophthalmic lenses, solar filters, Fresnel lenses, protective and safety shields, displays, substrates for optical disks, display panels, video display units, optical guides, components for mobile phones, and transparent tubes.