# US 5,710,189 A · Blowing agent composition and a method for making a blowing agent

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- Number: US 5,710,189 A
- Document ID: US5710189A
- Status: Granted
- Kind: A
- Application number: 08/769,458
- Filed: 1996-12-18
- Granted: 1998-01-20
- Earliest claimed: 1995-06-08
- Inventors: M. Karl Brandt
- Web page: https://patentgrep.com/patent/US5710189A

## CPC

- C08J 9/0023: {containing oxygen}
- C08J 9/0066: {Use of inorganic compounding ingredients}
- C08J 9/12: by a physical blowing agent
- C08J 9/14: organic
- C08J 2201/03: Extrusion of the foamable blend
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)

## Abstract

The present invention relates to a composition for use as a blowing agent in injection molding processes. More specifically, the present invention is a blowing agent composition comprising a molecular sieve and a foaming agent, wherein the foaming agent is carded by the molecular sieve and evolves to form foamed plastic products. In addition, the present invention is a method for preparing a blowing agent composition and a foamable blowing agent-resin mixture. Furthermore, the present invention is a foamed plastic resin containing a molecular sieve. Additionally, the present invention provides a composition and method for foaming moisture-sensitive polymers comprising the addition of molecular sieves and a poly-hydroxy ester. The present invention also advances a method of encapsulating a blowing agent on a polymer substrate and a corresponding encapsulated blowing agent composition.

## Claims

### Claim 1

A method for preparing a foamed resin composition, said method comprising the steps of:
mixing a blowing agent compound with a resin to form a first mixture, said blowing agent compound comprising a first molecular trap, a second molecular trap and a foaming material, said foaming material being carried by a preselected quantity of said second molecular trap, wherein said first molecular trap is a type 3A molecular trap and wherein said second molecular trap has a pore size greater than 3A, said first mixture having a temperature and a pressure; and
changing said temperature and said pressure of said first mixture until said temperature and said pressure are within a preselected range so that said foaming material evolves from said second molecular trap into said polymer to form said composition.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein said preselected quanity is between approximately 10% and 30% by weight of said second molecular trap.

### Claim 3 (depends on 1)

The method as recited in claim 1, wherein said first molecular trap is present in an amount between aproximately 0.6% and 1% by weight of said composition, and wherein said second molecular trap is present in an amount between approximately 2.0% and 4.0% by weight of said composition.

### Claim 4 (depends on 1)

The method as recited in claim 1, wherein said mixing step further comprises the step of adding a poly-hydroxy ester to said first mixture, said poly-hydroxy ester added in an amount between approximately 1% and 5% by weight of said composition.

### Claim 5 (depends on 1)

The method as recited in claim 1, wherein said mixing step further comprises the step of adding sorbitol ester, said sorbitol ester added in amount between approximately 1% and 5% by weight of said composition.

### Claim 6 (depends on 1)

The method as recited in claim 1, wherein mixing step further comprises the step of adding a micro crystalline wax, said wax added in an amount between approximately 1% and 2% by weight of said composition.

### Claim 7 (depends on 1)

The method as recited in claim 1, wherein said resin is selected from the group consisting of nylon, polycarbonates, acetals, poly-formaldehydes, and polyesters.

### Claim 8 (depends on 1)

The method as recited in claim 1, wherein said resin is polyethylene terephthalate.