Rigid PVC compounding compositions exhibiting weather resistance and PVC degradation resistance in hot sunny climates

Abstract

Rigid PVC resins are compounded with a chalk-like Caribbean micritic calcium carbonate to provide improved weathering resistance of rigid PVC articles subjected to external exposures of heat and sunlight. The effective resistance to heat and sunlight is substantially increased by rigid PVC resins compounded with European chalk and Caribbean micritic calcium carbonate, zinc dialkyl ester scavenger and organotin stabilizer to provide considerably increased PVC degradation resistance.

What is claimed is:  
     
         1 . A weather resistant polyvinyl chloride (PVC) resin compounding composition, comprising: 
 a rigid PVC resin; and    at least about 2 weight parts of non-precipitated, sedimentary Caribbean calcium carbonate per 100 weight parts of PVC resin, the calcium carbonate having a particle size less than about 10 microns and is about 98% or more by weight pure calcium carbonate essentially free of iron.    
     
     
         2 . The rigid PVC compounding composition of  claim 1 , wherein the Caribbean calcium carbonate particle size is less than about 6 microns.  
     
     
         3 . The rigid PVC compounding composition of  claim 1 , wherein the particle size of the Caribbean calcium carbonate is less than about 3 microns.  
     
     
         4 . The rigid PVC compounding composition of  claim 1  , wherein the particle size of the Caribbean calcium carbonate comprises from about 1 to about 3 microns or lower.  
     
     
         5 . The rigid PVC compounding composition of  claim 1 , wherein the Caribbean calcium carbonate contains impurities by weight are less than about 1% magnesium carbonate, less than about 0.3% acid insolubles, and less than about 0.1% silica.  
     
     
         6 . The rigid PVC compounding composition of  claim 1 , wherein the calcium carbonate is Jamaican calcium carbonate.  
     
     
         7 . The rigid PVC compounding composition of  claim 1 , containing from about 2 to about 50 weight parts of Caribbean calcium carbonate.  
     
     
         8 . The rigid PVC compounding composition of  claim 2 , containing from about 5 to about 15 weight parts of Jamaican calcium carbonate.  
     
     
         9 . The rigid PVC compounding composition of  claim 1 , wherein the Caribbean calcium carbonate is wet ground calcium carbonate.  
     
     
         10 . The rigid PVC compounding composition of  claim 1 , wherein the Caribbean calcium carbonate is dry ground calcium carbonate.  
     
     
         11 . The rigid PVC compounding composition of  claim 1 , wherein the micritic calcium carbonate particles are surface treated with a stearate.  
     
     
         12 . The rigid PVC compounding composition of  claim 1 , containing at least about 0.5 weight part s of organotin stabilizer based on 100 weight parts of PVC.  
     
     
         13 . The rigid PVC compounding composition of  claim 2 , containing from about 0.5 to about 3 weight parts of organotin stabilizer.  
     
     
         14 . The rigid PVC compounding composition of  claim 6 , containing from about 1 to about 2 weight parts of organotin stabilizer.  
     
     
         15 . The rigid PVC compounding composition of  claim 12 , wherein the organotin stabilizer comprises substituted mono-alkyl or dialkyl or trialkyl esters of tin with mono-, di-, or tri-substituted active mercapto groups or carboxylate groups.  
     
     
         16 . The rigid PVC compounding composition of  claim 15 , wherein the organotin stabilizer comprises mercapto groups.  
     
     
         17 . The rigid PVC compounding composition of  claim 12 , wherein the organotin stabilizer comprises a dialkyl mercapto compound.  
     
     
         18 . The PVC compounding composition of  claim 13 , wherein the organotin stabilizer comprises dialkyl ester mercaptide.  
     
     
         19 . The PVC compounding composition of  claim 13 , wherein the organotin stabilizer comprises dibutyl tin mercaptide.  
     
     
         20 . The rigid PVC compounding composition of  claim 8 , wherein the organotin stabilizer comprises dibutyl tin ethyl hexyl mercaptoacetate.  
     
     
         21 . The PVC compounding composition of  claim 15 , wherein the organotin stabilizer comprises active carboxylate groups.  
     
     
         22 . The PVC compounding composition of  claim 21 , wherein the carboxylate group comprises carboxylic acid.  
     
     
         23 . The rigid PVC compounding composition of  claim 21 , wherein the carboxylate group comprises an ester of carboxylic acid.  
     
     
         24 . The rigid PVC compounding composition of  claim 12 , containing at least about 0.1 weight parts of zinc dialkyl ester scavenger per 100 weight parts of PVC resin.  
     
     
         25 . The rigid PVC compounding composition of  claim 15 , containing at least about 0.1 weight parts of zinc dialkyl ester scavenger per 100 weight parts of PVC resin, provided the equivalents of active mercapto groups or carboxylate groups in the organotin are equal to or exceed the equivalents of dialkyl ester groups in the zinc dialkyl ester.  
     
     
         26 . The rigid PVC compounding composition of  claim 20 , containing from about 0.1 to about 2 weight parts of zinc dialkyl ester.  
     
     
         27 . The rigid PVC compounding composition of  claim 1 , wherein the PVC resin is essentially a homopolymer.  
     
     
         28 . The rigid PVC compounding composition of  claim 1 , wherein the PVC comprises a copolymer of copolymerized vinyl chloride monomer with less than 5% by weight copolymerized other unsaturated co-monomer.  
     
     
         29 . The rigid PVC compounding composition of  claim 28 , wherein the other unsaturated co-monomer is a vinyl monomer.  
     
     
         30 . The rigid PVC compounding composition of  claim 28 , wherein the other unsaturated co-monomer is a mono-ethylenically unsaturated monomer.  
     
     
         31 . A weather resistant polyvinyl chloride (PVC) compounding composition, comprising: 
 a rigid PVC resin;    at least about 2 weight parts of a non-precipitated, finely divided, chalk calcium carbonate having a particle size less than about 10 microns and at least about 98% pure calcium carbonate essentially free of iron;    at least about 0.5 weight parts of an alkyl substituted organotin having one, two, or three non-alkyl substituted active mercapto or carboxylate groups;    at least about 0.1 weight parts of zinc dialkyl ester scavenger, where the equivalents of zinc alkyl groups is less than the equivalents of non-alkyl active mercapto or carboxyl groups of the organotin; and    where all weight parts are based on 100 weight parts of PVC resin.    
     
     
         32 . The rigid PVC resin compounding composition of  claim 31 , containing from about 2 to about 50 weight parts of said calcium carbonate.  
     
     
         33 . The rigid PVC resin compounding composition of  claim 32 , containing from about 0.5 to about 3 weight parts of said organotin.  
     
     
         34 . The rigid PVC compounding composition of  claim 33 , wherein the organotin comprises a mercapto compound.  
     
     
         35 . The rigid compounding composition of  claim 33 , wherein the organotin comprises a carboxylate compound.  
     
     
         36 . The rigid PVC compounding composition of  claim 33 , containing from about 0.1 to about 2 weight parts of said zinc dialkyl ester.  
     
     
         37 . A process for producing a rigid polyvinyl chloride (PVC) resin compounding composition, the process comprising: 
 providing a non-precipitated, sedimentary Caribbean micritic calcium carbonate having a particle size less than about 10 microns, at least about 98% pure calcium carbonate, and essentially free of iron; and    mixing the calcium carbonate with PVC resin to form a PVC compounding composition containing at least about 2 weight parts calcium carbonate per 100 weight parts of PVC resin.    
     
     
         38 . The process of  claim 37 , wherein the compounded PVC resin and micritic calcium carbonate are mixed with at least about 0.5 weight parts of organotin stabilizer based on 100 weight parts of PVC resin.  
     
     
         39 . The process of  claim 38 , wherein the Caribbean calcium carbonate is wet or dry ground to provide a particle size less than about 6 microns.  
     
     
         40 . The process of  claim 39 , wherein the Caribbean calcium carbonate is wet ground to provide the particle size.  
     
     
         41 . The process of  claim 39 , wherein the Caribbean calcium carbonate is dry ground to provide the particle size.  
     
     
         42 . The process of  claim 37 , wherein the PVC compounding composition is formed into a rigid PVC article.  
     
     
         43 . The process of  claim 37 , wherein the PVC compounding composition is extruded into a rigid PVC article.  
     
     
         44 . The process of  claim 37 , wherein the PVC compounding composition is molded into a rigid PVC article.  
     
     
         45 . A rigid PVC article comprising the composition of  claim 1 .  
     
     
         46 . A rigid PVC article comprising the composition of  claim 8 .  
     
     
         47 . A rigid PVC article comprising the composition of  claim 12 .  
     
     
         48 . A rigid PVC article comprising the composition of  claim 20.