# US 11,028,319 B2 · Passive thermally driven variable opacity materials

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- Number: US 11,028,319 B2
- Document ID: US11028319B2
- Status: Granted
- Kind: B2
- Application number: 16/222,424
- Filed: 2018-12-17
- Published: 2019-06-20
- Granted: 2021-06-08
- Earliest claimed: 2017-12-20
- Assignees: E Ink Corporation
- Applicants: E Ink Corporation
- Inventors: Peter Carsten Bailey Widger; Jay William Anseth; Richard J. Paolini, Jr.; Craig Alan Breen; Wesley Viola
- Web page: https://patentgrep.com/patent/US11028319B2

## CPC

- C09K 9/02: Organic tenebrescent materials
- G02F 1/0147: {based on thermo-optic effects (G02F1/132 takes precedence)}
- B32B 17/10: of synthetic resin
- B32B 2307/41: Opaque
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM

## Abstract

A variable opacity material is provided that may be in the form of a mixture, such as an emulsion that contains a discontinuous aqueous polymeric solution having an LCST of 0 to 100° C. and a continuous phase containing a hydrophobic polymer, such as a polysiloxane. One or more salts, such as lithium bromide and sodium chloride, may be added to the aqueous solution to lower the LCST of the aqueous solution and to raise the refractive index of the aqueous polymeric solution to substantially match the refractive index of the hydrophobic polymer. The variable opacity materials may be applied in the form of a film to various substrates, such as glass.

## Claims

### Claim 1

A variable opacity material comprising an emulsion of an aqueous polymeric solution and a hydrophobic polymer, wherein:
the aqueous polymeric solution comprises hydroxypropyl cellulose or poly(N-isopropylacrylamide) and from 10 to 60 wt. % of an alkaline earth metal salt, wherein the hydroxypropyl cellulose or poly(N-isopropylacrylamide) phase separates at temperatures above the lower critical solution temperature (LCST),
the aqueous polymeric solution has an LCST from 0 to 100° C.,
the aqueous polymeric solution is emulsified in the hydrophobic polymer,
the aqueous polymeric solution is a discontinuous phase of the emulsion and the hydrophobic polymer is a continuous phase of the emulsion, and
below the LCST, the difference between refractive indices of the aqueous polymeric solution and the hydrophobic polymer is less than or equal to 0.05.

### Claim 2 (depends on 1)

The variable opacity material of claim 1, wherein the hydrophobic polymer comprises a polysiloxane.

### Claim 3 (depends on 2)

The variable opacity material of claim 2, wherein the polysiloxane comprises polydimethyl siloxane.

### Claim 4 (depends on 1)

The variable opacity material of claim 1, wherein the aqueous polymeric solution comprises a second salt.

### Claim 5 (depends on 4)

The variable opacity material of claim 4, wherein the aqueous polymeric solution comprises less than or equal to 5 wt. % of the second salt.

### Claim 6 (depends on 4)

The variable opacity material of claim 4, wherein the second salt is sodium chloride.

### Claim 7 (depends on 1)

The variable opacity material of claim 1, wherein the at least one salt is magnesium bromide.

### Claim 8 (depends on 1)

The variable opacity material of claim 1, wherein the aqueous polymeric solution comprises hydroxypropyl cellulose.

### Claim 9 (depends on 1)

The variable opacity material of claim 1, wherein the aqueous polymeric solution has an LCST greater than or equal to 25° C. and less than or equal to 35° C.

### Claim 10 (depends on 1)

The variable opacity material of claim 1, wherein the aqueous polymeric solution has a refractive index greater than or equal to 1.4.

### Claim 11 (depends on 1)

The variable opacity material of claim 1, wherein the aqueous polymeric solution comprises from 1 to 40 wt. % of a polymer.

### Claim 12 (depends on 1)

The variable opacity material of claim 1, wherein the hydrophobic polymer is curable.

### Claim 13 (depends on 12)

The variable opacity material of claim 12, wherein the hydrophobic polymer is thermally curable.

### Claim 14 (depends on 1)

The variable opacity material of claim 1, wherein the hydrophobic polymer is crosslinked.

### Claim 15 (depends on 1)

The variable opacity material of claim 1, wherein the continuous phase is crosslinked.

### Claim 16 (depends on 1)

A variable opacity film comprising the variable opacity material of claim 1 coated between two substrates.

### Claim 17 (depends on 16)

The variable opacity film of claim 16, wherein at least one of the substrates is transparent.