# US 7,608,207 B2 · Method for preparing a photochromic polyurethane latex and application to ophthalmic optics

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- Number: US 7,608,207 B2
- Document ID: US7608207B2
- Status: Granted
- Kind: B2
- Application number: 10/332,287
- Filed: 2001-07-06
- Published: 2004-01-22
- Granted: 2009-10-27
- Earliest claimed: 2000-07-07
- Assignees: Essilor International (Compagnie Generale d'Optique)
- Inventors: Nathaly Vassal; Jean-Pierre Vairon; Bernadette Charleux; Pascale Tardieu; Sylvette Maisonnier; Jean-Paul Cano
- Web page: https://patentgrep.com/patent/US7608207B2

## CPC

- C08K 5/3437: condensed with carbocyclic rings
- C08G 18/0823: {containing carboxylate salt groups or groups forming them}
- C08G 18/12: using two or more compounds having active hydrogen in the first polymerisation step
- C08G 18/4277: {Caprolactone and/or substituted caprolactone}
- C08G 18/6659: {with compounds of group C08G18/34}
- C08K 5/357: Six-membered rings
- G02B 5/23: Photochromic filters
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

The method of the invention comprises: a) forming a hydrophilic polyurethane prepolymer with isocyanate end groups, by the polyaddition reaction of at least one polyol and at least one diisocyanate in the presence of at least one internal emulsifying agent; b) mixing the polyurethane prepolymer with a photochromic agent; c) adding water or a mixture of water and solvent, under agitation, to the mixture of the polyurethane prepolymer and the photochromic agent, to form an emulsion; and d) adding at least one chain extension agent to the emulsion and performing a chain extension reaction to give the final photochromic polyurethane latex. Application to the production of ophthalmic articles having photochromic properties.

## Claims

### Claim 1

A method of preparing a photochromic polyurethane latex comprising:
forming a hydrophilic polyurethane prepolymer with isocyanate end groups, by polyaddition of at least one polyol and at least one polyisocyanate in the presence of at least one internal emulsifying agent, wherein the quantities of the polyol and polyisocyanate are such that the molar ratio of OH groups/NCO groups is about 1/2;
mixing the polyurethane prepolymer with a photochromic agent;
adding water or a mixture of water and solvent, under agitation, to the mixture of the polyurethane prepolymer and the photochromic agent, to form an emulsion; and
adding at least one chain extension agent to the emulsion and performing a chain extension reaction to give a final photochromic polyurethane latex.

### Claim 2 (depends on 1)

The method of claim 1, wherein the internal emulsifying agent is an ionic emulsifying agent.

### Claim 3 (depends on 2)

The method of claim 2, wherein the ionic internal emulsifying agent is an anionic internal emulsifying agent.

### Claim 4 (depends on 3)

The method of claim 3, wherein the internal emulsifying agent is a diamine sulfonate, a diol sulfonate, or a dihydroxycarboxylic acid.

### Claim 5 (depends on 4)

The method of claim 4, wherein the internal emulsifying agent is α,α-dimethylolpropionic acid.

### Claim 6 (depends on 2)

The method of claim 2, further comprising neutralizating the polyurethane prepolymer prior to mixing it with the photochromic agent.

### Claim 7 (depends on 6)

The method of claim 6, wherein neutralizing comprises the addition of a tertiary amine.

### Claim 8 (depends on 1)

The method of claim 1, wherein the polyisocyanate is a diisocyanate.

### Claim 9 (depends on 8)

The method of claim 8, wherein the diisocyanate is further defined as toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, diphenylmethane-4,4′-diisocyanate, diphenylmethane-2,4′-diisocyanate, paraphenylene diisocyanate, biphenyldiisocyanate, 3,3′-dimethyl-4,4′-diphenylene diisocyanate, tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, 2,2,4-trimethyl hexane-1,6-diisocyanate, lysine methyl ester diisocyanate, bis(isocyanatoethyl)fumarate, isophorone diisocyanate, ethylene diisocyanate, dodecane-1,12-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene-2,4-diisocyanate, hexahydrotoluene-2,6-diisocyanate, hexahydrophenylene-1,3-diisocyanate, hexahydrophenylene-1,4-diisocyanate, perhydrodiphenylmethane-2,4′-diisocyanate, perhydrophenylmethane-4,4′-diisocyanate, or a mixture of two or more such diisocyantates.

### Claim 10 (depends on 9)

The method of claim 9, wherein the diisocyanate is isophorone diisocyanate.

### Claim 11 (depends on 1)

The method of claim 1, wherein the polyol is further defined as a polyol of low molecular weight, a polyester polyol, a polyether polyol, a polyol containing an amide group, a polyacrylic polyol, an epoxy polyol, a polyvinyl polyol, a urethane polyol, or a mixture of two or more such polyols.

### Claim 12 (depends on 11)

The method of claim 11, wherein the polyol is a polycaprolactone diol.

### Claim 13 (depends on 1)

The method of claim 1, comprising adding a quantity of the photochromic agent representing from 0.1 to 15% by weight with respect to the total weight of polyol, polyisocyanate, internal emulsifying agent, and photochromic agent.

### Claim 14 (depends on 13)

The method of claim 13, further defined as comprising adding a quantity of the photochromic agent representing from 2 to 10% by weight with respect to the total weight of polyol, polyisocyanate, internal emulsifying agent, and photochromic agent.

### Claim 15 (depends on 1)

The method of claim 1, wherein the photochromic agent is added in the form of a solution in a solvent.

### Claim 16 (depends on 15)

The method of claim 15, wherein the solvent is N-methylpyrrolidone.

### Claim 17 (depends on 1)

The method of claim 1, further defined as comprising the addition of a solvent during the process of forming the hydrophilic polyurethane prepolymer.

### Claim 18 (depends on 17)

The method of claim 17, wherein the solvent is N-methylpyrrolidone.

### Claim 19 (depends on 1)

The method of claim 1, wherein the chain extension agent is an aliphatic diamine, a cycloaliphatic diamine, a triamine, a tetramine, or a mixture of two or more such extension agents.

### Claim 20 (depends on 19)

The method of claim 19, wherein the chain extension agent is ethylenediamine, diethylenetriamine, or tris(2-aminoethyl)amine.

### Claim 21 (depends on 1)

The method of claim 1, wherein the final polyurethane latex has a concentration of solids of at least 30% by weight.

### Claim 22 (depends on 21)

The method of claim 21, wherein the final polyurethane latex has a concentration of solids of 30 to 35% by weight.

### Claim 23 (depends on 1)

The method of claim 1, wherein the final polyurethane latex has a particle size of from 50 to 300 nm.

### Claim 24 (depends on 23)

The method of claim 23, wherein the final polyurethane latex has a particle size of from 150 to 250 nm.

### Claim 25 (depends on 1)

The method of claim 1, comprising using a quantity of internal emulsifying agent of from 3 to 5% by weight with respect to the total weight of polyol, polyisocyanate, and internal emulsifying agent.

### Claim 26 (depends on 1)

The method of claim 1, wherein the photochromic agent is chromene, a chromene compound, an oxazine compound, a fulgide, a fulgimide, or a metallic salt of dithizonate.

### Claim 27 (depends on 1)

The method of claim 1, further defined as comprising using a molar ratio prepolymer/chain extension agent of between 0.2 and 2.

### Claim 28

A method of preparing a photochromic polyurethane latex comprising:
forming a hydrophilic polyurethane prepolymer with isocyanate end groups, by polyaddition of at least one polyol and at least one polyisocyanate in the presence of at least one internal emulsifying agent, wherein the amount of the internal emulsifying agent is from 3 to 5% by weight with respect to the total weight of polyol, polyisocyanate, and internal emulsifying agent;
mixing the polyurethane prepolymer with a photochromic agent;
adding water or a mixture of water and solvent, under agitation, to the mixture of the polyurethane prepolymer and the photochromic agent, to form an emulsion; and
adding at least one chain extension agent to the emulsion and performing a chain extension reaction to give a final photochromic polyurethane latex.