Alternative methods to control crosslinking in high impact polystyrene

Patent metadata

Field	Value
Publication number	US-9809699-B2
Application number	US-201514927528-A
Country	US
Kind code	B2
Filing date	Oct 30, 2015
Priority date	Oct 30, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

High impact polystyrene may be formed with increased swell index and reduced or eliminated discoloration. A process of forming high impact polystyrene may include providing a polymerization system including a polymerization reactor and a devolatilizer. High impact polystyrene may be formed in the polymerization reactor, and sent to the devolatilizer. A polar antioxidant having a hindered phenol structure and an aliphatic amine group, and with a phosphite antioxidant may be added to the polymerization system. In another process, a chemical retarder and a fluorescent whitening agent may be added to the polymerization system. In another process, a chemical retarder that inhibits free radical rubber crosslinking may be added to the polymerization system.

First claim

What is claimed:

1. A process comprising:
providing a polymerization system comprising a polymerization reactor upstream of a devolatilizer;
forming a high impact polystyrene within the polymerization reactor;
sending the high impact polystyrene to the devolatilizer, wherein the high impact polystyrene contains oxidizing agents;
adding a chemical retarder to the polymerization system at or upstream of the devolatilizer, wherein the chemical retarder comprises an antioxidant having a hindered phenol structure and an aliphatic amine group; and
adding a fluorescent whitening agent to the polymerization system at or upstream of the devolatilizer.

2. The process of claim 1 , wherein the polar antioxidant has the structure:

3. The process of claim 1 , wherein the chemical retarder is present in the high impact polystyrene in an amount ranging from greater than 0 ppm to 1000 ppm.

4. The process of claim 1 , wherein the oxidizing agents comprise peroxides, acids, aldehydes, or combinations thereof.

5. The process of claim 1 , wherein the fluorescent whitening agent is 2,2′-(1,2-ethenediyl)bis(4,1-phenylene)bisbenzoxazole.

6. The process of claim 1 , further comprising obtaining high impact polystyrene from the devolatilizer, wherein the fluorescent whitening agent reflects light having wavelengths ranging from greater than 445 to less than 510 nm.

7. The process of claim 1 , wherein the chemical retarder reacts with the oxidizing agents, and wherein a product of reaction between the chemical retarder and the oxidizing agents reflects light having wavelengths ranging from greater than 510 to less than 590 nm.

8. The process of claim 1 , further comprising obtaining high impact polystyrene from the devolatilizer, wherein a product of reaction between the chemical retarder and the oxidizing agents reflects light having wavelengths ranging from greater than 510 to less than 590 nm, wherein the fluorescent whitening agent reflects light having wavelengths ranging from greater than 445 to less than 510 nm, and wherein the obtained high impact polystyrene exhibits a whitening effect.

9. The process of claim 1 , wherein the fluorescent whitening agent is present in the high impact polystyrene in an amount ranging from greater than 0 ppm to 2000 ppm.

10. The process of claim 1 , further comprising obtaining high impact polystyrene from the devolatilizer exhibiting a yellowness index of less than 0 and a swell index of at least 5% greater than the swell index of a high impact polystyrene obtained in an otherwise identical process in which the fluorescent whitening agent is not added to the polymerization system.

11. The process of claim 1 , wherein the high impact polystyrene exhibits a yellowness index that is less than the yellowness index of high impact polystyrene obtained in an otherwise identical process in which the fluorescent whitening agent is not added to the polymerization system, and wherein the high impact polystyrene exhibits a swell index that is greater than the swell index of high impact polystyrene obtained in an otherwise identical process in which the fluorescent whitening agent is not added to the polymerization system.

12. The process of claim 1 , further comprising adding a phosphite antioxidant to the polymerization system at or upstream of the devolatilizer.

Assignees

• Fina Technology

Inventors

• Trimino Giovanni
• Deanda Carlos
• Knoeppel David W

Classifications

• C08K5/353

  Five-membered rings · CPC title

• C08F12/08 Primary

  Styrene · CPC title

• C08K5/17

  Amines; Quaternary ammonium compounds · CPC title

• C08K5/524 Primary

  Esters of phosphorous acids, e.g. of H3PO3 · CPC title

• C08K5/13

  Phenols; Phenolates · CPC title