BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a process for providing a binder for mineral fibers, i.e. man made vitreous fibers, for example glass, slag or stone wool, a binder obtainable via such a process, and a mineral wool product comprising such a binder. 
     2. Description of the Related Art 
     Mineral wool products generally comprise mineral fibers bonded together by a cured thermoset polymeric material. One or more streams of molten glass, slag or stone are drawn into fibers and blown into a forming chamber where they are deposited as a web on to a travelling conveyer. The fibers, while airborne in the forming chamber and while still hot are sprayed with a binder. The coated fibrous web is then transported from the chamber to a curing oven where heated air is blown through the mat to cure the binder and rigidly bond the mineral wool fibers together. 
     Phenol-formaldehyde binders are widely used in the mineral wool industry since they have a low viscosity in the uncured state, yet still form a rigid thermoset polymeric matrix for the mineral fibers when cured. 
     However the use of phenol formaldehyde binders is becoming increasingly undesirable due to the use and release of environmentally unfavourable chemicals during the process. 
     The use of β-hydroxyalkylamides to cure polycarboxy polymers such as polyacrylic acid in order to provide a binder is known. 
     A problem with polyacrylics cured by β-hydroxyalkylamides is that mineral wool products bound with such a resin normally exhibit good mechanical properties before ageing, but after exposure to high humidities and increased temperatures, for example above 40 degrees centigrade, the mechanical properties are drastically reduced. 
     There is therefore a desire to develop a binder which improves on the known binders. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an alternative binder aimed at overcoming one or more of these problems. 
     According to a first aspect of the present invention, there is provided a process for providing a binder for mineral wool products said process comprising the steps of:
         mixing together under reactive conditions a carboxylic acid with an alkanolamine.   The resulting binder when utilized for a mineral wool product, provides the mineral wool product with desirable mechanical properties after ageing, subjection to tear strain and exposure to high humidities and increased temperatures.   The carboxylic acid and the alkanolamine are preferably firstly mixed together under reactive conditions to provide a resin, which resin optionally is subsequently mixed with a separate carboxylic acid group containing polymer to form a binder.   The carboxylic acid is preferably a di-, tri-, or tetra carboxylic acid having a molecular weight of about 1000 or less, preferably about 500 or less, and most preferably about 200 or less, most preferably a di-carboxylic acid having the general formula:
 
COOH—(CR 1 R 2 ) n —COOH
 
wherein n≧2 and preferably n≧4, and wherein R 1  and R 2  are independently selected from H or a lower alkyl group, preferably a methyl or ethyl group.
       

     The carboxylic acid is preferably selected from the group consisting essentially of: adipic acid, citric acid, trimellitic acid, sebacic acid, azelaic acid, and succinic acid and is most preferably adipic acid. 
     The alkanolamine is preferably selected from the group comprising di, and tri-alkanolamines, and can be a secondary beta-hydroxy alkylamine, preferably an N-substituted alkanolamine selected from the group consisting essentially of, di-ethanolamine, 1-(m)ethyldiethanolamine, n-butyldiethanolamine, 3-amino-1,2-propanediol, 2-amino-1,3,-propanediol, tris(hydroxymethyl)aminomethane, most preferably being diethanolamine. 
     The mole ratio of the carboxylic acid to the alkanolamine in the binder preferably lies in the range of 0.1-1:1-0.1 and the weight percentage of the carboxylic acid group containing polymer in the binder can lie in the range of 0.5-50, for example 10-40, preferably 15-30, most preferably about 20. 
     The alkanolamine is preferably firstly heated to around 60° C., whereafter the carboxylic acid is added and the temperature of this mixture is subsequently raised to about at least 90° C., preferably a temperature lying in the range of about 95-200, for example about 120-150° C. 
     The carboxylic acid group containing polymer preferably has a molecular weight lying in the ranges of 1000-300000, for example 1000-250000, preferably 1000-200000 most preferably having a molecular weights of around 60000, around 100000 and around 190000. 
     The carboxylic acid group containing polymer preferably comprises one or more of the following: polyacrylic acid, polymethacrylic acid, polymaleic acid and/or co-polymers thereof, preferably being selected from one or more of the following:
         HF-05A, Rohm &amp; Haas, an acrylic emulsion,   ACUSOLE 190™, Rohm &amp; Haas, a styrene/acrylic emulsion,   ACUMER 1510™, Rohm &amp; Haas, poly (acrylic acid) with an average MW ca. 60,000,   41.600-2, from the Aldrich Chemical Company Inc., poly(acrylic acid) with an average MW ca. 250,000.       

     One or more of the following additives can be added to the binder:
         a coupling agent, for example an aminosilane, preferably gamma-aminopropyltriethoxysilane,   a polymerisation accelerator, a curing accelerator and optionally further standard mineral wool binder additives.       

     In order to improve the water solubility of the resin a base might be added till a pH up to 7. The weight % of base in the resin reaction mixture, typically the weight % of the base calculated by weight of the solids in the reaction mixture, lies in the range of up to 20%, preferably up to 10%, more preferably 1-5% and most preferably 4%. The base is preferably mixed with a polyacrylic acid and added to the resin reaction mixture after the resin reaction is preferably stopped by water addition. The weight % of polyacrylic acid in the mixture lies in the range up to 50%, for example 40%, preferably 30% and most preferably up to 25%. Stopping the resin reaction is preferably accomplished by adding in an amount equal to the weight of the solids in the resin mixture, 25% more than the weight of solids in the resin mixture, or 50% more than the weight of solids in the resin mixture. Accordingly, the base can first be added after the resin is prepared. Suitable bases include NH 3 , DEA, TEA, optionally mixed with a polyacrylic acid such as Acumer 1510 produced by Rohm and Haas, MW about 60,000. 
     In order to improve the aging constancy properties a silane may be added. The silane usually but is not restricted to be added during the binder preparation or directly (separately) at the line. The amount would normally be in the range from 0.1% to 5% (0.2%-3%) and is preferably measured by the weight of the resin solids. Preferred amount is approximately 1%. The silane is most preferably prehydrolysed gamma-aminopropyltriethoxysilane (VS 142/Vitco). 
     According to further aspects of the present invention there is provided a binder obtainable according to this process, a process for providing a mineral wool product, a mineral wool product and the use of a reaction mixture of an alkanolamine and a carboxylic acid, optionally mixed with a carboxylic acid group containing polymer, as a binder for a mineral wool product. 
     The invention will now be further illustrated by way of the following examples and results. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     EXAMPLE 1 
     158 g diethanolamine was placed in a 1-liter glass reactor provided with a double jacket and an agitator. Temperature of the diethanolamine was raised to 60° C. whereafter 99 g adipic acid was added slowly. The temperature was raised to 95° C. After a reaction time of 1 hour at about 95° C. the reaction was stopped by the addition of 200 g water. The reaction product was a clear, colourless, low viscous liquid, dilutable with water. 
     EXAMPLE 2 
     158 g diethanolamine was placed in a 1-liter glass reactor provided with a double jacket and an agitator. Temperature of the diethanolamine was raised to 60° C. whereafter 175 g adipic acid was added slowly. The temperature was raised to 95° C. After a reaction time of 1 hour at about 95° C. the reaction was stopped by the addition of 200 g water. The reaction product was a clear, colourless, low viscous liquid, dilutable with water. 
     EXAMPLE 3 
     67,2 g triethanolamine was mixed with 33,0 g adipic acid at room temperature. After the solution had turned clear 60 ml temperate water was added. The mixture was a clear, colourless, low viscous liquid, dilutable in water. 
     EXAMPLE 4-6 
     Resins were made using the same procedure as in example 1. The following amounts of chemicals were used: 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Alkanolamine 
                 Polycarboxylic acid 
                 Water 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 4 
                 158 g Diethanolamine 
                 243 g Azelaic Acid 
                 200 ml 
               
               
                 Example 5 
                 158 g Diethanolamine 
                 141 g Sebacic Acid 
                 200 ml 
               
               
                 Example 6 
                 158 g Diethanolamine 
                  89 g Succinic Acid 
                 200 ml 
               
               
                   
               
             
          
         
       
     
     EXAMPLE 7 
     158 g diethanolamine was placed in a 1-liter glass reactor provided with a double jacket and an agitator. The temperature of the diethanolamine was raised to 60° C. whereafter 99 g adipic acid was slowly added. The temperature was subsequently raised to about 130° C., the temperature being maintained between 128 and 135° C. After a reaction time of 3 hours the reaction was stopped by the addition of water. 
     All the produced reaction products in examples 4-7 were clear colourless low viscous liquids, dilutable in water. 
     EXAMPLE 8 
     Preparation and testing of selected binder samples to evaluate the binding strength towards shots with mineral fibre composition (Grit bar test). As shots are considered unfiberized fiber material with identical composition as the fibers. 
     Shots with size between 0,25 and 0,5 mm diameter were used to make bars with dimensions 140 mm×25 mm×10 mm. 
     A binder solution was prepared comprising 80% of the resins from examples 1-7 mixed at room temperature with 20% of a commercial polyacrylic resin. 
     As polyacrylic acids were used the commercial types from Rohm &amp; Haas: HF-05A, Acusole 190 and Acumer 1510, and a polyacrylic acid with an average mole weight of 250.000 (Aldrich Chemical Company Inc. 41.600-2). 
     For making the bars 90 ml binder solution with 15% solids content and 0,2% silane coupling agent of binder solids were mixed with 450 g shots. 
     The coupling agent was gamma-aminopropyltriethoxysilane. 
     Out of the 450 g shots mixed with binder solution, 8 bars were made which were cured 2 hours at 200° C. in an incubator. 
     Four of the bars were broken directly (dry strength), the other 4 are placed 3 hours in 80° C. water before they are broken (wet strength). 
     The binding strength was determined by breaking the bars in a measuring device, where the clamping length is 100 mm and the velocity of the compressing beam was 10 mm/min. Using the clamping length, width and thickness of the bars, the bending strength was determined in N/mm 2 . 
     For comparison a commercial product Primid XL-552 from EMS Chemie AG was used. Primid XL-552 is the reaction product of a dimethylester of adipic acid and diethanolamine, whereby the inventors have shown that 100% Primid is not curable since only free OH-groups are present which do not cross-link. A mixture of 80% primid and 20% PAA yielded a very fast curing time (45s (HF-05) and 20s (Mw 250,000) at 200° C.) but the products have no remaining strength after ageing. The results are shown in table 2. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                   
                 Remaining 
               
               
                   
                   
                 Unaged 
                 Aged 
                 strength 
               
               
                   
                 Polyacryl- 
                 strength 
                 strength 
                 (aged/ 
               
               
                 Resin 
                 ic acid 
                 N/mm 2   
                 N/mm 2   
                 unaged) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 80% 
                 20% HF05 
                 9.6 
                 2.0 
                 21% 
               
               
                 Example 1 
               
               
                 80% 
                 20% PAA MW 
                 9.7 
                 4.6 
                 47% 
               
               
                 Example 1 
                 250000 
               
               
                 80% 
                 20% HF05 
                 10.0 
                 5.3 
                 53% 
               
               
                 Example 2 
               
               
                 80% 
                 20% PAA MW 
                 6.9 
                 4.5 
                 66% 
               
               
                 Example 2 
                 250000 
               
               
                 80% 
                 20% HF05 
                 7.7 
                 6.2 
                 81% 
               
               
                 Example 3 
               
               
                 comparison 
                 20% HF05 
                 3.6 
                 0 
                 0% 
               
               
                 example 
               
               
                 80% Primid 
               
               
                 XL-552 
               
               
                 60% 
                 40% HF05 
                 8.1 
                 4.0 
                 49% 
               
               
                 Example 2 
               
               
                 20% 
                 80% HF05 
                 8.5 
                 1.5 
                 18% 
               
               
                 Example 2 
               
               
                 20% 
                 80% PAA, 
                 4.5 
                 4.0 
                 89% 
               
               
                 Example 2 
                 Mw 250,000 
               
               
                 80% 
                 20% PAA 
                 6.6 
                 3.1 
                 47% 
               
               
                 Example 4 
                 MW 2,000 
               
               
                 80% 
                 20% PAA 
                 8.0 
                 4.7 
                 59% 
               
               
                 Example 5 
                 Mw 2,000 
               
               
                 80% 
                 20% PAA 
                 7.5 
                 0.4 
                 5% 
               
               
                 Example 6 
                 Mw 250,000 
               
               
                 80% 
                 20% 
                 8.0 
                 2.4 
                 30% 
               
               
                 Example 7 
                 Acusol 190 
               
               
                 80% 
                 20% Acumer 
                 9.2 
                 3.2 
                 35% 
               
               
                 Example 7 
                 1510 
               
               
                   
               
             
          
         
       
     
     Measurement of Curing Times for Selected Examples 
     A few droplets of the binder to be examined were placed on a microscope cover glass. The glass was dried in a heating cupboard at 90° C. for 45 min. 
     After drying the cover glass was placed on a heating stage at 250° C. and while stirred with a piece of metal wire (straightened paper-clips) the time was measured until the binder was cured. 
     The results are shown in table 3. 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Results 
               
             
          
           
               
                   
                 Polyacylic 
                 Curing time 
                 Curing time 
               
               
                 Resin 
                 acid 
                 200° C. 
                 250° C. 
               
               
                   
               
               
                 80% Example 1 
                 20% HF05 
                 — 
                 90 s 
               
               
                 80% Example 1 
                 20% PAA, Mw 
                 — 
                 25 s 
               
               
                   
                 250,000 
               
               
                 80% Example 2 
                 20% HF05 
                 140-160 s 
                 45 s 
               
               
                 80% Example 2 
                 20% PAA, Mw 
                 — 
                 25 s 
               
               
                   
                 250,000 
               
               
                 80% Example 4 
                 20% HF05 
                 173 s 
                 43 s 
               
               
                 80% Example 5 
                 20% HF05 
                 285 s 
                 50 s 
               
               
                 80% Example 7 
                 20% 
                  35 s 
                 — 
               
               
                   
                 Acusol 190 
               
               
                 80% Example 7 
                 20% Acumer 
                  30 s 
                 — 
               
               
                   
                 1510 
               
               
                   
               
             
          
         
       
     
     As polyacrylic acids were used the commercial types from Rohm &amp; Haas: HF-05A, Acusole190 and Acumer 1510, and two pure polyacrylic acids with average mole weights of 2000 and 250,000 respectively (Aldrich Chemical Company Inc. 32,366-7 and 41,600-2) 
     EXAMPLE 9 
     20.8 kg Diethanolamixe were transferred to a 80 liter steel reactor provided with an agitator and a heating/cooling jacket and heated to 60° C. 23.0 kg Adipic Acid were added to the reactor in 5 portions and the temperature raised to a reaction temperature of 95° C. After reaction for 1 hour 26.3 kg temperate water were added, whereafter the resin was cooled to room temperature. 
     The resulting resin was a clear colourless low viscous liquid dilutable with water. 
     At room temperature 80% of the above resin was mixed with 20% of a commercial Polyacrylic resin from Rohm &amp; Haas: HF-05. 
     The produced resin was after mixing with water and addition of 0.2% of a silane coupling agent used as a binder in a production trial on a standard stonewool line. The product produced was a standard slab with a density of 100 kg/m 3 , 100 mm thickness and with approximately 3% binder content. 
     As a comparison a trial was made with two commercial polyacrylic resins. HF-05 and QRXP 1513 both from Rohm &amp; Haas. Both resins were diluted with water and added 0.2% of a silane coupling agent. 
     The coupling agent was γ-aminopropyltriethoxysilane. 
     The mechanical strengths were measured according to EN1607 (delamination strength). The delamination strength was measured on both unaged and after exposure to high humidity and increased temperature in a climate chamber (70° C./95 RH; aged samples) 
     Results from the testing are shown in tables 4, 5 and 6 below. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Delamination 
                   
               
               
                   
                   
                   
                   
                 Delamination 
                 strength 
               
               
                   
                   
                   
                   
                 strength 
                 Aged 
               
               
                   
                 Binder 
                 Oil 
                 Density 
                 Unaged 
                 (70° C./95% 
                 Remaining 
               
               
                 Binder 
                 content 
                 content 
                 Kg/m 3   
                 kPa 
                 RH) kPa 
                 strength 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Binder 
                 3.1% 
                 0.2% 
                 98 
                 9.7 
                 4.0 
                 41% 
               
               
                 according 
               
               
                 Example 8 
               
               
                 Comparison 
                 3.3% 
                 0.2% 
                 101 
                 7.2 
                 1.3 
                 18% 
               
               
                 example 
               
               
                 HF-05 
               
               
                 Comparison 
                 3.1% 
                 0.2% 
                 98 
                 12.6 
                 1.6 
                 13% 
               
               
                 example 
               
               
                 QRXP 
               
               
                 Comparison 
                 3.3% 
                 0.2% 
                 99 
                 10.9 
                 4.6 
                 42% 
               
               
                 example 
               
               
                 Standard 
               
               
                 phenolic 
               
               
                 resin 
               
               
                   
               
             
          
         
       
     
     EXAMPLE 10 
     
       
         
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
               
                   
               
               
                   
                   
                   
                   
                   
                   
                   
                 Curing 
                 Curing 
                   
               
               
                   
                   
                 Poly- 
                   
                 Accele- 
                   
                 Reaction 
                 time 
                 time 
                 Silane 
               
               
                 Ex 
                 Amine 
                 acid 
                 Water 
                 rator 
                 Base 
                 conditions 
                 200° C. 
                 250° C. 
                 [%] 
               
               
                   
               
             
             
               
                 10 
                 25.5 kg 
                 17.6 kg 
                 32.5 l 
                 20% 
                 DEA 
                 60°/130° 
                 140 s 
                 35 s 
                 0.2 
               
               
                   
                 DEA 
                 ADP 
                   
                 PAA 
                   
                 for 3 
               
               
                   
                   
                   
                   
                   
                   
                 hours 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Delamina- 
                   
               
               
                   
                   
                   
                 Den- 
                 Delamination 
                 tion strength, 
                 Re- 
               
               
                   
                 Binder 
                 Oil 
                 sity 
                 strength, 
                 aged (70° C./ 
                 maining 
               
               
                   
                 content 
                 content 
                 [kg/ 
                 unaged 
                 95% RH) 
                 strength 
               
               
                 Ex 
                 [%] 
                 [%] 
                 m 3 ] 
                 [kPa] 
                 [kPa] 
                 [%] 
               
               
                   
               
             
             
               
                 10 
                 3.5 
                 0.2 
                 140 
                 10.1 
                 3.3 
                 36 
               
               
                   
               
             
          
         
       
     
     EXAMPLE 11 
     Resin: 
     116 kg DEA was transferred to a 400 l reactor and heated to 60° C. and stirred. 
     16.3 kg ADP was added and the mixture heated and reacted at 130° C. for 60 minutes. 
     Thereafter cooled to 85° C. and added (THPA) 33.8 kg. Thereafter 82.5 kg PTA was added and the temperature raised to 130° C. and kept there for 120 minutes. 
     Thereafter the reaction mixture was cooled to 110° C. and 100 kg water added. 
     The temperature stabilised at approx. 50° C. The mixture was stirred for further 15 minutes until homogenous. 
     The resin was cooled and transferred to a storage tank. 
     Resin solids content 62.2% determined at 200° C. Rest monomers 39% DEA of added, 12% THPA of added, 25% PTA of added. Average molweight about 600. 
     On a sample, a factory trial was carried out, whereby 4% DEA and 25% solids Acumer 1510 calculated on resin solids, 0.4% of sum solids silane and water to 25% solids content, was added and analysed. 
     Results of Factory Trial 
     
         
         Binder yield 60% 
         Delamination strength (EN 1607) 13.4 kPa (Terraenbatts Industri)—Aged 3.6 kPa (70° C./95% RH) 
         Tensile strength 5.5 kPa (Flexi A Batts) 
       
    
     EXAMPLE 12 
     Resin 
     24 kg DEA was transferred to a 80 l reactor and heated to 60° C. and stirred. 
     6.7 kg ADP was added and the mixture heated and reacted at 130° C. for 60 minutes. 
     Thereafter cooled to 85° C. and added 6.9 kg THPA. Thereafter 16.9 kg PTA was added and the temperature raised to 130° C. and kept there for 120 minutes. 
     Thereafter the reaction mixture was cooled to 110° C. and 20.5 kg water added. The temperature stabilises at approx. 50° C. 
     The mixture was stirred for further 15 minutes until homogenous. 
     The resin was cooled and transferred to a storage tank. 
     Resin solids content 63.4% determined at 200° C. Rest monomers 37% DEA of added, 14% THPA of added, 25% PTA of added. Average molweight about 600. 
     On a sample, a factory trial was carried out, whereby 4% DEA and 25% solids Acumer 1510 calculated on resin solids, 0.4% of sum solids silane and water to 25% solids content, was added and analysed. 
     Results of Factory Trial 
     
         
         Binder yield 70% 
         Delamination strength (EN 1607) 12.1 kPa (Terraenbatts Industri)—Aged 4.3 kPa (70° C./95% RH) 
       
    
     The invention is not limited to the above description, the requested rights are determined by the following claims.
Process for providing a binder for mineral wool products, said process comprising the steps of: mixing together under reactive conditions a carboxylic acid with an alkanolamine, whereby optionally these are firstly mixed to provide a resin, which resin is subsequently reacted with a separate carboxylic acid group containing polymer.