US2003176548A1PendingUtilityA1

Stiff and impact resistant compositions containing poly(propylene) or poly(ethylene/propylene) and calcium carbonate for closures

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Priority: Jul 12, 2000Filed: Feb 10, 2003Published: Sep 18, 2003
Est. expiryJul 12, 2020(expired)· nominal 20-yr term from priority
Inventors:Anatoliy Goldman
B65D 41/34B29C 48/00Y10T428/1352B65D 41/0428B29C 48/12B29C 48/40C08K 9/04
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Claims

Abstract

Stiff and impact resistant closures derived from the stiff and impact resistant blends including poly(propylene) or poly(ethylene/propylene) and calcium carbonate; stiff and impact resistant compositions including poly(propylene) or poly(ethylene/propylene) and calcium carbonate; methods for increasing stiffness and impact resistance of a poly(propylene) or poly(ethylene/propylene) resin, or a closure; and a method for measuring the impact strength of a closure or a resin at a reduced temperature are disclosed. A presently preferred blend contains from about 40 to about 60 weight percent of poly(propylene) or poly(ethylene/propylene) and from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, the treated particles having a particle size of from about 2.5 to about 3.5 microns.

Claims

exact text as granted — not AI-modified
I claim:  
     
         1 . A closure for a container comprising a top and a depending shell, said closure is formed of a stiff and impact resistant polymeric blend having from about 40 to about 60 weight percent of a polymer selected from the group consisting of poly(propylene) and poly(ethylene/propylene); and from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns, 
 wherein said closure has a falling weight impact resistance at −20° C. of from about 0.4 to about 2.5 joules and a stiffness at room temperature of from about 1800 to about 2200 megapascals.    
     
     
         2 . A closure for a container comprising a top and a depending shell, said closure is formed of a stiff and impact resistant polymeric blend having from about 40 to about 60 weight percent of a polymer selected from the group consisting of poly(propylene) and poly(ethylene/propylene) and from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns, 
 wherein said closure has a falling weight impact resistance at room temperature of from about 0.8 to about 4.0 joules and a stiffness at room temperature of from about 1800 to about 2200 megapascals.    
     
     
         3 . A closure for a container comprising a top and a depending shell, said closure is formed of a stiff and impact resistant polymeric blend having from about 40 to about 60 weight percent of a polymer selected from the group consisting of poly(propylene) and poly(ethylene/propylene) and from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns, 
 wherein said closure has a falling weight impact resistance at −20° C. of from about 0.4 to about 2.5 joules, a falling weight impact resistance at room temperature of from about 0.8 to about 4.0 joules and a stiffness at room temperature of from about 1800 to about 2200 megapascals.    
     
     
         4 . A method of increasing stiffness and impact resistance in a closure comprising the steps of: 
 a) making a stiff and impact resistant polymeric blend by 
 compounding from about 40 to about 60 weight percent of a polymer selected from the group consisting of poly(propylene) and poly(ethylene/propylene) with  
 from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns; and then,  
   b) molding said blend into a closure.    
     
     
         5 . The method of  claim 4  wherein said compounding is carried out in an extruder at a die temperature of 350-425° F., a rate of 20-40 lbs/hr and a screw speed of 200-500 rpm to obtain good dispersion of said calcium carbonate particles.  
     
     
         6 . The method of  claim 5  wherein said extruder is a twin screw extruder 
 having at least a first temperature zone, a second temperature zone, a third temperature zone and a fourth temperature zone.  
 
     
     
         7 . The method of  claim 6  wherein said first, second, third and fourth temperature zones are each 400° F.  
     
     
         8 . A stiff and impact resistant polymeric composition comprising: 
 from about 40 to about 60 weight percent of a polymer selected from the group consisting of poly(propylene) and poly(ethylene/propylene); and,    from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns,    wherein said composition has a falling weight impact resistance at −20° C. of from about 0.4 to about 2.5 joules and a stiffness at room temperature of from about 1800 to about 2200 megapascals.    
     
     
         9 . The composition of  claim 8  wherein said fatty acid is stearic acid.  
     
     
         10 . The composition of  claim 8  further comprising at least one additive selected from the group consisting of pigments, lubricants, anti-oxidants, emulsifiers and a combination thereof.  
     
     
         11 . A stiff and impact resistant polymeric composition comprising: 
 from about 40 to about 60 weight percent of a polymer selected from the group consisting of poly(propylene) and poly(ethylene/propylene); and,    from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns,    wherein said composition has a falling weight impact resistance at room temperature of from about 0.8 to about 4.0 joules and a stiffness at room temperature of from about 1800 to about 2200 megapascals.    
     
     
         12 . The composition of  claim 11  wherein said fatty acid is stearic acid.  
     
     
         13 . The composition of  claim 11  further comprising at least one additive selected from the group consisting of pigments, lubricants, anti-oxidants, emulsifiers and a combination thereof.  
     
     
         14 . A stiff and impact resistant polymeric composition comprising: 
 from about 40 to about 60 weight percent of a polymer selected from the group consisting of poly(propylene) and poly(ethylene/propylene); and,    from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns,    wherein said composition has an impact resistance at −20° C. of from about 0.4 to about 2.5 joules, a falling weight impact resistance at room temperature of from about 0.8 to about 4.0 joules and a stiffness at room temperature of from about 1800 to about 2200 megapascals.    
     
     
         15 . The composition of  claim 14  wherein said fatty acid is stearic acid.  
     
     
         16 . The composition of  claim 14  further comprising at least one additive selected from the group consisting of pigments, lubricants, anti-oxidants, emulsifiers and a combination thereof.  
     
     
         17 . A method for increasing the impact strength and stiffness of a polypropylene or poly(ethylene/propylene) resin comprising the step of 
 compounding from about 40 to about 60 weight percent of said resin with from about 25 to about 35 weight percent of calcium carbonate particles treated with fatty acid, wherein said calcium carbonate particles have a particle size of from about 2.5 to about 3.5 microns.    
     
     
         18 . The method of  claim 17  wherein said impact strength to be improved is room temperature impact strength, cold temperature impact strength, or both room temperature impact strength and cold temperature impact strength.  
     
     
         19 . The method of  claim 17  wherein said compounding is carried out in an extruder at a die temperature of 350-425° F., a rate of 20-40 lbs/hr and a screw speed of 200-500 rpm to obtain good dispersion of said calcium carbonate particles.  
     
     
         20 . The method of  claim 19  wherein said extruder is a twin screw extruder 
 having at least a first temperature zone, a second temperature zone, a third temperature zone and a fourth temperature zone.  
 
     
     
         21 . The method of  claim 20  wherein said first, second, third and fourth temperature zones are each 400° F.  
     
     
         22 . A method for measuring impact resistance of a closure at a reduced temperature comprising the steps of: 
 a) conditioning a closure for forty hours at 23° C. and 50% relative humidity according to ASTM D-4101 to produce a conditioned closure;    b) acclimating said conditioned closure for two hours at a reduced temperature to produce an acclimated closure; and then,    c) measuring impact resistance of said acclimated closure by the falling weight impact test according to ASTM D-5628-94.    
     
     
         23 . The method of  claim 22  wherein said reduced temperature is selected from the group consisting of 0° C., −20° C. and −40° C.

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