Solar collector

Abstract

A solar collector which comprises a mineral wool insulation based on man-made vitreous fibers (MMVF) which are bonded by a formaldehyde-free polymeric binder system. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.

1 . A solar collector, wherein the collector comprises a mineral wool insulation based on man-made vitreous fibers (MMVF) which are bonded by a formaldehyde-free polymeric binder system.  
   
   
       2 . The solar collector of  claim 1 , wherein the MMVF comprise one or more fibers selected from glass wool, glass filaments, ceramic fibers, basalt fibers, slag wool, stone wool and rock wool.  
   
   
       3 . The solar collector of  claim 1 , wherein the insulation comprises black mineral wool.  
   
   
       4 . The solar collector of  claim 1 , wherein the formaldehyde-free polymeric binder system comprises a water-soluble reaction product of an alkanolamine with a carboxylic anhydride which is obtainable by reacting at least one alkanolamine with at least one carboxylic anhydride and, optionally, treating the reaction product with a base.  
   
   
       5 . The solar collector of  claim 1 , wherein the formaldehyde-free polymeric binder system comprises: 
 (a) a polyacid component having acid groups, or anhydride or salt derivatives thereof; and    (b) a polyhydroxy component having hydroxyl groups;    wherein a pH of the binder composition is greater than about 7.    
   
   
       6 . The solar collector of  claim 5 , wherein the pH of the binder composition is up to about 10.  
   
   
       7 . The solar collector of  claim 5 , wherein a ratio of the number of molar equivalents of acid groups, or anhydride or salt derivatives thereof, present on the polyacid component to the number of molar equivalents of hydroxyl groups present on the polyhydroxy component is from about 0.6:1 to about 1.2:1.  
   
   
       8 . The solar collector of  claim 1 , wherein the formaldehyde-free polymeric binder system comprises a heat-curable aqueous composition comprising 
 (a) at least one carboxyl-containing addition copolymer synthesized from 
 from about 50% to about 99.5% by weight of at least one ethylenically unsaturated mono- and/or dicarboxylic acid,  
   from about 0.5% to about 50% by weight of at least one ethylenically unsaturated compound selected from esters of ethylenically unsaturated monocarboxylic acids and monoesters and diesters of ethylenically unsaturated dicarboxylic acids with an amine having at least one hydroxyl group,    (b) up to about 20% by weight of at least one monomer,    (c) at least one β-hydroxyalkylamine of relatively high functionality, and    (d) optionally, at least one surfactant.    
   
   
       9 . The solar collector of  claim 1 , wherein the polymeric binder system is present in an amount of from about 0.1% to about 10% by weight of the bonded mineral wool insulation in a dry state.  
   
   
       10 . The solar collector of  claim 1 , wherein the collector comprises an absorber and a housing and wherein the polymeric binder system is present in a concentration gradient over a thickness of the mineral wool insulation such that a concentration of the binder system is lowest in an upper region next to the absorber and is higher in a lower region adjacent to the housing.  
   
   
       11 . The solar collector of  claim 1 , wherein the mineral wool insulation has a thermal conductivity of ≦about 0.040 W/mK.  
   
   
       12 . The solar collector of  claim 1 , wherein the mineral wool insulation has a bulk density of from about 10 to about 120 kg/m 3 .  
   
   
       13 . A solar collector, wherein the collector comprises a mineral wool insulation based on man-made vitreous fibers (MMVF) which comprise one or more fibers selected from glass wool, glass filaments, ceramic fibers, basalt fibers, slag wool, stone wool and rock wool and which are bonded by a formaldehyde-free polymeric binder system which is present in an amount of from about 0.2% to about 5% by weight of the bonded mineral wool insulation in a dry state.  
   
   
       14 . The solar collector of  claim 13 , wherein the insulation comprises black mineral wool.  
   
   
       15 . The solar collector of  claim 13 , wherein the mineral wool insulation has a thermal conductivity of ≦about 0.040 W/mK and a bulk density of from about 10 to about 120 kg/m 3 .  
   
   
       16 . The solar collector of  claim 13 , wherein the formaldehyde-free polymeric binder system comprises a water-soluble reaction product of an alkanolamine with a carboxylic anhydride which is obtainable by reacting at least one alkanolamine with at least one carboxylic anhydride and, optionally, treating the reaction product with a base.  
   
   
       17 . The solar collector of  claim 13 , wherein the formaldehyde-free polymeric binder system comprises: 
 (a) a polyacid component having acid groups, or anhydride or salt derivatives thereof; and    (b) a polyhydroxy component having hydroxyl groups;    wherein a pH of the binder composition is from greater than about 7 to about 10.    
   
   
       18 . The solar collector of  claim 17 , wherein a ratio of the number of molar equivalents of acid groups, or anhydride or salt derivatives thereof, present on the polyacid component to the number of molar equivalents of hydroxyl groups present on the polyhydroxy component is from about 0.6:1 to about 1.2:1.  
   
   
       19 . The solar collector of  claim 17 , wherein the formaldehyde-free polymeric binder system comprises a heat-curable aqueous composition comprising 
 (a) at least one carboxyl-containing addition copolymer synthesized from 
 from about 50% to about 99.5% by weight of at least one ethylenically unsaturated mono- and/or dicarboxylic acid,  
 from about 0.5% to about 50% by weight of at least one ethylenically unsaturated compound selected from esters of ethylenically unsaturated monocarboxylic acids and monoesters and diesters of ethylenically unsaturated dicarboxylic acids with an amine having at least one hydroxyl group,  
   (b) up to about 20% by weight of at least one monomer,    (c) at least one β-hydroxyalkylamine of relatively high functionality, and    (d) optionally, at least one surfactant.    
   
   
       20 . A solar heating system, wherein the system comprises the solar collector of  claim 1.