US2003203142A1PendingUtilityA1

Process for injection molding crystal polystyrene to form compact disc trays

45
Priority: Apr 23, 1999Filed: Apr 18, 2003Published: Oct 30, 2003
Est. expiryApr 23, 2019(expired)· nominal 20-yr term from priority
Inventors:Michael Schäfer
B29K 2105/26Y10T428/1352B29L 2017/005G11B 23/0316B29K 2221/003B29C 45/0013B29C 45/0001G11B 33/0405
45
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Claims

Abstract

A process for mixing plastic resins to produce a material having properties similar to medium and high impact polystyrene after thermoforming. The process includes mixing crystal polystyrene and a styrenic thermoplastic elastomer to form a mixture for thermoforming. The process enables the substitution of crystal polystyrene for medium and high impact polystyrene in the production of items such as compact disc trays and the like.

Claims

exact text as granted — not AI-modified
What is claimed is:  
     
         1 . A method of providing a mixture of plastic resin for thermoforming, comprising the steps of: 
 a) providing a predetermined quantity of crystal polystyrene;    b) providing a predetermined quantity of thermoplastic elastomer;    c) combining the crystal polystyrene and thermoplastic elastomer to form a mixture for thermoforming; and    d) thermoforming the mixture to form an article.    
     
     
         2 . The method of  claim 1 , wherein the crystal polystyrene comprises approximately 75-95% of the mixture by weight.  
     
     
         3 . The method of  claim 1 , wherein the thermoplastic elastomer is a styrenic thermoplastic elastomer.  
     
     
         4 . The method of  claim 1 , wherein the thermoplastic elastomer comprises 2-15% of the mixture by weight.  
     
     
         5 . The method of  claim 1 , wherein the thermoforming comprises injection molding.  
     
     
         6 . The method of  claim 5 , wherein the article comprises a compact disc tray.  
     
     
         7 . A method of providing a mixture of plastic resin for injection molding comprising the steps of: 
 a) providing a predetermined quantity of crystal polystyrene;    b) providing a predetermined quantity of thermoplastic elastomer;    c) providing a predetermined quantity of color additive;    d) combining the crystal polystyrene, thermoplastic elastomer, and color additive to form a mixture for thermoforming; and    d) thermoforming the mixture to form an article.    
     
     
         8 . The method of  claim 7 , wherein the crystal polystyrene comprises approximately 75-95% of the mixture by weight.  
     
     
         9 . The method of  claim 7 , wherein the thermoplastic elastomer is a styrenic thermoplastic elastomer.  
     
     
         10 . The method of  claim 7 , wherein the thermoplastic elastomer comprises approximately 2-15% of the mixture by weight.  
     
     
         11 . The method of  claim 7 , wherein the color additive comprises approximately 2-6% of the mixture by weight.  
     
     
         12 . The method of  claim 7 , wherein the thermoforming comprises injection molding.  
     
     
         13 . The method of  claim 12 , wherein the article comprises a compact disc tray.  
     
     
         14 . A method of providing a mixture of plastic resin for injection molding comprising the steps of: 
 a) providing a predetermined quantity of crystal polystyrene;    b) providing a predetermined quantity of thermoplastic elastomer;    c) providing a predetermined quantity of color additive;    d) providing a predetermined quantity of regrind selected from the group consisting of crystal polystyrene, medium impact polystyrene and high impact polystyrene;    e) combining the crystal polystyrene, thermoplastic elastomer, color additive, and regrind to form a mixture for thermoforming; and    f) thermoforming the mixture to form an article.    
     
     
         15 . The method of  claim 14 , wherein the crystal polystyrene comprises approximately 75-95% of the mixture by weight.  
     
     
         16 . The method of  claim 14 , wherein the thermoplastic elastomer is a styrenic thermoplastic elastomer.  
     
     
         17 . The method of  claim 14 , wherein the thermoplastic elastomer comprises approximately 2-15% of the mixture by weight.  
     
     
         18 . The method of  claim 14 , wherein the color additive comprises approximately 2-6% of the mixture by weight.  
     
     
         19 . The method of  claim 14 , wherein the regrind comprises approximately 5-20% of the mixture by weight.  
     
     
         20 . The method of  claim 14 , wherein the thermoforming comprises injection molding.  
     
     
         21 . The method of  claim 20 , wherein the article comprises a compact disc tray.  
     
     
         22 . An article formed of molded thermoplastic material comprising crystal polystyrene in an amount of from about 75% to about 95% by weight and styrenic thermoplastic elastomer in an amount from about 5% to about 25% by weight.  
     
     
         23 . The article of  claim 22 , further comprising a color additive in the amount of approximately 2-6% of the mixture by weight.  
     
     
         24 . The article of  claim 22 , further comprising a regrind in the amount of approximately 5-20% of the mixture by weight.  
     
     
         25 . The article of  claim 22 , wherein the article is a compact disc tray.  
     
     
         26 . The article of  claim 23 , wherein the article is a compact disc tray.  
     
     
         27 . The article of  claim 24 , wherein the article is a compact disc tray.

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