Hydrophilic contact lens material

Claim 2

As a material for the formation of hydrophilic articles, the composition consisting of: a. a major amount of hydroxy alkyl acrylate or methacrylate, b. between 0.01 and 0.25% by weight of said composition of a non-water-soluble alkyl diester of acrylic acid or methacrylic acid and having no free hydrophilic groups, and c. between 0.5% and about 10% by weight of said composition of a low molecular weight acid having an unsaturated double bond and selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid.

Claim 3

The composition of claim 1 wherein said diester is present in the preferred range of from 0.15 to 0.25% by weight of said composition, said diester functioning as a cross-linking agent.

Claim 4

The composition of claim 1 wherein said free acid is present in the range of from 0.5 to 1.5% by weight of said composition.

Claim 5

A non-aqueous composition useful for the formation of a hydrophilic terpolymer from which hydrophilic articles can be made, said non-aqueous composition consisting of: a. a major amount of hydroxy alkyl acrylate or methacrylate selected from the class consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol monomethacrylate, b. between 0.01 and 0.25% by weight of said composition of an alkyl diester of acrylic acid or methacrylic acid selected from the class consisting of ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, hexane glycol diacrylate, hexane diol dimethacrylate, polyethylene glycol diacrylate having a molecular weight less than about 500, and polyethylene glycol dimethacrylate having a molecular weight less than about 500, said diester being non-water-soluble, and c. between 0.5% and about 10% by weight of said composition of a low molecular weight acid having an unsaturated double bond and selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid.

Claim 6

A non-aqueous composition useful for the formation of a hydrophilic terpolymer from which hydrophilic articles can be made, said non-aqueous composition consisting of: a. a major amount of hydroxy alkyl acrylate or methacrylate selected from the class consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol monomethacrylate, b. between 0.01 and 0.25% by weight of said composition of an alkyl diester of acrylic acid or methacrylic acid selected from the class consisting of ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, hexane glycol diacrylate, hexane diol dimethacrylate, polyethylene glycol diacrylate having a molecular weight less than about 500, and polyethylene glycol dimethacrylate having a molecular weight less than about 500, said diester being non-water-soluble, and c. between 0.5% and about 10% by weight of said composition of a low molecular weight acid having an unsaturated double bond and selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid.

Claim 7

A soft contact lens composed of the polymerization product of the composition of claim 4.

Claim 8

A rigid hydrophilic terpolymer consisting of the composition of: a. a major amount of a hydroxy alkyl acrylate or methacrylate, b. between 0.01 and 0.25% by weight of said composition of a non-water-soluble alkyl diester of acrylic acid or methacrylic acid and having no free hydrophilic groups, and c. between 0.5% and about 10% by weight of said composition of a low molecular weight acid having an unsaturated double bond and selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid, said composition being polymerized with a free radical organic peroxide polymerization catalyst.

Claim 9

A rigid hydrophilic terpolymer consisting of the composition of: a. a major amount of a hydroxy alkyl acrylate or methacrylate, b. between 0.01 and 0.25% by weight of said composition of a non-water-soluble alkyl diester of acrylic acid or methacrylic acid and having no free hydrophilic groups, and c. between 0.5% and about 10% by weight of said composition of a low molecular weight acid having an unsaturated double bond and selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid, said composition being polymerized with a free radical organic peroxide polymerization catalyst.

Claim 10

A process for the formation of hydrophilic gel material from commercial grade hydroxy ethyl methacrylate (HEMA) containing as impurities an alkyl diester having acrylic or methacrylic groups and the free parent acid of said HEMA, said diester consisting of an alkyl glycol diacrylate or dimethacrylate having no free hydrophilic groups, comprising: distilling said commercial grade HEMA to obtain a distillate consisting of a major amount of hydroxy ethyl methacrylate, less than 0.25% by weight of said diester and less than 10% by weight of said free acid, said distillate being non-aqueous, adding to said distillate sufficient free acid to bring the free acid concentration to a selected value within the range of from 0.5% to about 10% by weight of the composition resultant from said addition of free acid, and polymerizing said resultant composition to provide a rigid hydrophilic gel terpolymer.

Claim 11

A process for the formation of hydrophilic gel material from commercial grade hydroxy ethyl methacrylate (HEMA) containing as impurities an alkyl diester having acrylic or methacrylic groups and the free parent acid of said HEMA, said diester consisting of an alkyl glycol diacrylate or dimethacrylate having no free hydrophilic groups, comprising: distilling said commercial grade HEMA to obtain a distillate consisting of a major amount of hydroxy ethyl methacrylate, less than 0.25% by weight of said diester and less than 10% by weight of said free acid, said distillate being non-aqueous, adding to said distillate sufficient free acid to bring the free acid concentration to a selected value within the range of from 0.5% to about 10% by weight of the composition resultant from said addition of free acid, and polymerizing said resultant composition to provide a rigid hydrophilic gel terpolymer.

Claim 12

The process according to claim 7 wherein said distillation comprises vacuum distillation carried out at a temperature of less than about 85° C. and wherein an initial forecut of the distillate is discarded.

Claim 13

The process according to claim 7, together with the additional steps of: mechanically forming a contact lens from said rigid hydrophilic gel terpolymer, and hydrating said lens.

Claim 14

A process for forming a soft contact lens, comprising: providing a non-aqueous mixture of a major amount of hydroxy alkyl acrylate or methacrylate, between 0.01 and 0.25% by weight of said mixture of an alkyl diester of acrylic acid or methacrylic acid, said diester having no free hydrophilic groups, and between 0.5% and about 10% by weight of said mixture of a low molecular weight acid having an unsaturated double bond, said acid being selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid, polymerizing said mixture with a catalyst to form a sparingly cross-linked, rigid, non-hydrated, hydrophilic terpolymer, mechanically forming an optical contact lens from said rigid hydrophilic terpolymer, and hydrating said lens subsequent to mechanical formation.

Claim 15

A process for forming a soft contact lens, comprising: providing a non-aqueous mixture of a major amount of hydroxy alkyl acrylate or methacrylate, between 0.01 and 0.25% by weight of said mixture of an alkyl diester of acrylic acid or methacrylic acid, said diester having no free hydrophilic groups, and between 0.5% and about 10% by weight of said mixture of a low molecular weight acid having an unsaturated double bond, said acid being selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid, polymerizing said mixture with a catalyst to form a sparingly cross-linked, rigid, non-hydrated, hydrophilic terpolymer, mechanically forming an optical contact lens from said rigid hydrophilic terpolymer, and hydrating said lens subsequent to mechanical formation.

Claim 16

A contact lens formed by the process of claim 10, and wherein greater than about 2% of said low molecular weight acid is included in said mixture so that the resultant terpolymer has a water concentration of greater than about 57% by weight upon hydration.

Claim 17

A process for forming a soft contact lens, comprising: providing a non-aqueous mixture of a major amount of hydroxy alkyl acrylate or methacrylate, between 0.01 and 0.25% by weight of said mixture of an alkyl diester of acrylic acid or methacrylic acid, and between 0.5% and about 10% by weight of said mixture of a low molecular weight acid having an unsaturated double bond, polymerizing said mixture with a catalyst to form a sparingly cross-linked, rigid, non-hydrated, hydrophilic terpolymer, mechanically forming an optical contact lens from said rigid hydrophilic terpolymer, and hydrating said lens subsequent to mechanical formation, and wherein; said acrylate or methacrylate is selected from the class consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol monomethacrylate, wherein; said non-water-soluble diester is selected from the class consisting of ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, hexane diol diacrylate, hexane diol dimethacrylate, polyethylene glycol diacrylate having a molecular weight below about 500 and polyethylene glycol dimethacrylate having a molecular weight below about 500, and wherein; said acid is selected from the class consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid.

Claim 18

A process for forming a soft contact lens, comprising: providing a non-aqueous mixture of a major amount of hydroxy alkyl acrylate or methacrylate, between 0.01 and 0.25% by weight of said mixture of an alkyl diester of acrylic acid or methacrylic acid, and between 0.5% and about 10% by weight of said mixture of a low molecular weight acid having an unsaturated double bond, polymerizing said mixture with a catalyst to form a sparingly cross-linked, rigid, non-hydrated, hydrophilic terpolymer, mechanically forming an optical contact lens from said rigid hydrophilic terpolymer, and hydrating said lens subsequent to mechanical formation, and wherein; said acrylate or methacrylate is selected from the class consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol monomethacrylate, wherein; said non-water-soluble diester is selected from the class consisting of ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, hexane diol diacrylate, hexane diol dimethacrylate, polyethylene glycol diacrylate having a molecular weight below about 500 and polyethylene glycol dimethacrylate having a molecular weight below about 500, and wherein; said acid is selected from the class consisting of acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid and isocrotonic acid.

Claim 19

A contact lens formed by the process of claim 12 and hydrated to a water concentration of at least 25% by weight.