# US 7,745,668 B2 · Processes for reducing color in polytrimethylene ether glycol polymers

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- Number: US 7,745,668 B2
- Document ID: US7745668B2
- Status: Granted
- Kind: B2
- Application number: 11/833,453
- Filed: 2007-08-03
- Published: 2007-11-29
- Granted: 2010-06-29
- Earliest claimed: 2003-05-06
- Assignees: E. I. Du Pont de Nemours and Company
- Inventors: Hari Babu Sunkara; Hiep Quang Do
- Web page: https://patentgrep.com/patent/US7745668B2

## CPC

- C07C 41/36: by solid-liquid treatment; by chemisorption
- C08G 65/34: from hydroxy compounds or their metallic derivatives {(C08G65/26 takes precedence)}
- C08G 65/46: Post-polymerisation treatment, e.g. recovery, purification, drying
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS

## Abstract

Processes for reducing color in PO3G are provided. The processes include contacting PO3G with an activated carbon and then separating the PO3G from the activated carbon by, for example, filtration. The process provides PO3G having an APHA color less than that before contact with the absorbent. The processes are desirably used for polymers having a molecular weight of about 250 to about 5000.

## Claims

### Claim 1

A process consisting of contacting PO3G having an initial color with an adsorbent consisting of activated carbon and separating the PO3G and activated carbon, wherein the PO3G, after contact with the activated carbon, has an APHA color lower than the initial color wherein the PO3G is contacted with about 0.1 to about 5 weight % of the activated carbon based on the weight of the PO3G.

### Claim 2 (depends on 1)

The process of claim 1, wherein the PO3G has a molecular weight of about 250 to about 10,000.

### Claim 3 (depends on 1)

The process of claim 1, wherein the PO3G has a molecular weight of about 500 to about 5000.

### Claim 4 (depends on 1)

The process of claim 1, wherein the PO3G has a molecular weight of about 500 to about 4000.

### Claim 5 (depends on 1)

The process of claim 1, wherein the PO3G is contacted with about 0.25 to about 3 weight % of the activated carbon based on the weight of the PO3G.

### Claim 6 (depends on 1)

The process of claim 1, wherein the contacting is conducted at a temperature of about 100 to about 150° C.

### Claim 7 (depends on 1)

The process of claim 1, wherein the contacting is conducted at a temperature of about 25° to about 100° C.

### Claim 8 (depends on 1)

The process of claim 1, wherein the contacting is conducted for a period of about 5 to about 60 minutes.

### Claim 9 (depends on 1)

The process of claim 1, wherein the contacting is conducted for a period of about 10 to about 30 minutes.

### Claim 10 (depends on 1)

The process of claim 1, wherein the PO3G has an initial APHA color of at least 50.

### Claim 11 (depends on 1)

The process of claim 1, wherein the PO3G has an initial APHA color of about 70 to about 300.

### Claim 12 (depends on 1)

The process of claim 1, wherein the APHA color is reduced by at least about 10%.

### Claim 13 (depends on 1)

The process of claim 1, wherein the APHA color is reduced by at least about 30% as compared to the initial APHA color.

### Claim 14 (depends on 1)

The process of claim 1, wherein the APHA color is reduced by at least about 50% as compared to the initial color.

### Claim 15

A process consisting of:
a. providing reactant comprising 1,3-propanediol and polycondensation catalyst;
b. polycondensing the reactant to PO3G having an initial color;
c. contacting the PO3G with activated carbon; and
d. separating the PO3G and activated carbon,
such that the PO3G, after contact with the activated carbon, has a APHA color lower than the initial color herein the PO3G is contacted with about 0.1 to about 5 weight % of the activated carbon based on the weight of the PO3G, and then contacting is conducted at a temperature of about 100 to about 150° C.

### Claim 16

A process consisting of contacting PO3G with activated carbon and separating the PO3G and activated carbon, wherein the PO3G has an initial APHA color, before contact with activated carbon, of about 70 to about 300, wherein the PO3G, after contact with the activated carbon, has an APHA color that is reduced by at least 10% as compared with the initial APHA color wherein the PO3G is contacted with about 0.1 to about 5 weight % of the activated carbon based on the weight of the PO3G.