Abstract:
The present invention relates to a method of producing a powder adhesive for attaching a veneer comprising the steps of: (a) providing expanded perlite; (b) providing cement; (c) providing a dispersible polymer powder; and (d) mixing said expanded perlite, said cement, and said dispersible polymer powder, for creating said adhesive for attaching stone veneer.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to the use of compositions containing expanded perlite. More particularly, the present invention relates to the use of compositions of expanded perlite for the construction industry. 
       BACKGROUND 
       [0002]    Volcanic glass, such as perlite, forms when molten rock, i.e. lava, pours out of a volcano and cools rapidly, therefore, there is no time for crystals to form or for water to escape. Instead, the lava hardens immediately, into a material which contains 2-5% water. 
         [0003]    Perlite is known in industry in two forms: crude and expanded. Crude perlite is prepared by the crushing and screening of perlite into various size fractions. Expanded perlite is perlite after it has been heated. When heated, it can expand to as much as twenty times its original volume. This expansion is the result of heated water: when the glassy lava rock is heated to 890° C., the water molecules trapped in the rock turn into vapor which causes the rock to expand, similarly as the water in popcorn cause the kernel to pop when it is heated. It is the presence of these trapped water molecules which accounts for the physical properties of expanded perlite. 
         [0004]    Expanded perlite can be manufactured to weigh between 32-240 kg/m 3 , making it adaptable for numerous applications in the construction, industrial, chemical, horticultural and petrochemical industries. 
         [0005]    U.S. Pat. No. 7,736,574 discloses a method for the production of perlite products such as sheets, panels or bricks. The disclosed method involves first providing a quantity of expanded perlite and treating the perlite by applying a cement binder thereto, so as to at least partially encapsulate the perlite with binder. Thereafter, an amount of cement is added to the binder-treated perlite and a mixture is created. The described mixture is then formed and allowed to harden to yield solid articles. Nevertheless, the disclosed method is used for yielding perlite based solid articles. 
         [0006]    It would therefore be desired to propose a system void of these deficiencies. 
       SUMMARY 
       [0007]    It is an object of the present invention to provide a light weight composition for use in the construction industry. 
         [0008]    It is another object of the present invention to provide a light weight adhesive, for attaching any natural or synthetic stone veneer. 
         [0009]    It is still another object of the present invention to provide an ecological adhesive for gluing stone tiles, which has a long open time. 
         [0010]    It is still another object of the present invention to provide an adhesive or plaster which has improved thermal and acoustic insulating properties. 
         [0011]    Other objects and advantages of the invention will become apparent as the description proceeds. 
         [0012]    The present invention relates to a powder adhesive composition, for attaching veneer, which comprises at least 10% of expanded perlite of its total volume. 
         [0013]    Preferably, the composition further comprises a cellulose ethers compound, a dispersible polymer powder; and a fiber compound. 
         [0014]    Preferably, the composition further comprises cement. 
         [0015]    Preferably, the cement is white cement. 
         [0016]    In one embodiment, the cement is Portland cement. 
         [0017]    In one embodiment, the composition further comprises an accelerator. 
         [0018]    Preferably, the expanded perlite comprises at least 1% of the total mass of the composition. 
         [0019]    Preferably, the cellulose ethers compound is a Methocel polymer. 
         [0020]    Preferably, the dispersible polymer powder is Wacker&#39;s Vinnapas 5025L. 
         [0021]    Preferably, the fiber compound is a polypropylene compound. 
         [0022]    Preferably, the adhesive composition is used for gluing a tile. 
         [0023]    Preferably, the adhesive composition is used for gluing a stone tile. 
         [0024]    The present invention also relates to a method of producing a powder adhesive for attaching a veneer comprising the steps of (a) providing expanded perlite; (b) providing cement; (c) providing a dispersible polymer powder; and (d) mixing said expanded perlite, said cement, and said dispersible polymer powder, for creating said adhesive for attaching stone veneer. 
         [0025]    Preferably, the method further comprises adding an accelerator. 
         [0026]    Preferably, the method further comprises adding a cellulose ethers compound. 
         [0027]    Preferably, the method further comprises adding a fiber compound. 
     
    
     DETAILED DESCRIPTION 
       [0028]    Prior art stone veneer powder adhesives, such as BG Bond BG40 or Sika Ceram-202, for gluing ceramic tiles, typically has a density of more than 1400 kg/m 3 . The heavy weight of these prior art adhesives is due, inter alia, to the weight of the sand in the adhesive. The heavy weight of these prior art adhesives is costly in terms of transportation and problematic in terms of handling, e.g. manual carrying. Furthermore, if the sand is not dried properly, before it is mixed into the adhesive, some of the adhesive&#39;s polymers can be ruined, effectively weakening the adhesive. 
         [0029]    In one embodiment a composition is proposed, for use in the construction industry, which uses expanded perlite. The expanded perlite may be used as a substitute for the sand, used in prior art compositions. The composition, which comprises expanded perlite, may be used for creating an adhesive, plaster, or any kind of material that hardens on drying and may be used for indoors and/or outdoors gluing on and/or coating walls, ceilings, floors, or for any other construction use. For example, the composition may be used as a powder adhesive, when mixed with water it can be used for gluing natural or synthetic stone tiles to a wall. Thus, for example, a powder adhesive composition for a stone veneer, which uses expanded perlite instead of sand, may have a density of approximately 500 kg/m 3 , which results in a lighter weight, for the same volume, compared to a typical prior art powder adhesive. The composition, which comprises expanded perlite, may have different consistencies such as powder, granular, cream, etc. The composition, which comprises expanded perlite, may be stored in sacks, bags, buckets, or any other known container. In one embodiment, the expanded perlite comprises at least 80% of the total volume of the composition. In one embodiment, the expanded perlite comprises at least 10% of the total volume of the composition. 
         [0030]    In one embodiment expanded vermiculite may be used instead of expanded perlite. Vermiculite is a hydrous, silicate mineral that is classified as a phyllosilicate and that expands greatly when heated. Vermiculite may be formed by weathering or hydrothermal alteration of biotite or phlogopite 
         [0031]    In one embodiment, the composition, comprising expanded perlite, may be used for creating a lightweight powder veneer adhesive. The term veneer is meant to include any protective or ornamental facing which can be glued to any horizontal or vertical surface. The adhesive may be used for gluing stone such as granite porcelain, ceramic, mosaic, porcelain, marble, brick, or any other synthetic or natural stone to a wall, ceiling, floor or any other surface. The powder adhesive may be mixed with water for creating a glue having cream like texture, which hardens on drying. The glue may be used for gluing any stone tiles as a protective and/or decorative covering for exterior or interior horizontal or vertical surfaces. In one embodiment, the powder adhesive composition, for attaching stone veneer, comprises at least 9% of expanded perlite of its total mass. In one embodiment, the powder adhesive composition, for attaching stone veneer, comprises at least 1% of expanded perlite of its total mass. 
         [0032]    In one embodiment the adhesive composition, for attaching veneer, may comprise, in addition to the expanded perlite, a cellulose ethers compound. The cellulose ethers compound may be Methocel, which is water-soluble methylcellulose and has hydroxypropyl methylcellulose polymers, or any other cellulose ether that is made for use with cement. In one embodiment the cellulose ethers compound may be added to the adhesive composition at a ratio of between 30-40% of the mass of the expanded perlite. The cellulose ethers compound may be used to enhance some of the qualities of the adhesive composition such as providing workable quality to the composition and/or extending the open time of the composition, and/or improving the water saturation of the composition, where open time is the time after the adhesive is applied during which a serviceable bond can be made. 
         [0033]    In one embodiment the adhesive composition for attaching veneer may also comprise a dispersible polymer. The dispersible polymer may be Wacker&#39;s Vinnapas 5025L, which is a leveling dispersible powder based on vinyl acetate and ethylene, or any other hydroscopic compound which is dispersible in water. In one embodiment the dispersible polymer may be added to the adhesive composition at a ratio of between 200-250% of the mass of the expanded perlite. 
         [0034]    In one embodiment the adhesive composition for attaching veneer may also comprise a fiber compound such as Adfil construction fibres or any other polypropylene compound having a fiber Length of 6 mm or any other chemical or synthetic fiber compound which may be used for cement based adhesives. In one embodiment the fiber compound may be added to the adhesive composition at a ratio of between 0.6-0.9% of the mass of the expanded perlite. 
         [0035]    In one embodiment the adhesive composition for attaching veneer may also comprise cement such as white cement, Portland cement, or any type of cement or aluminous cement. In one embodiment the cement may be added to the adhesive composition at a ratio of between 800-950% of the mass of the expanded perlite. 
         [0036]    In one embodiment the adhesive composition, comprising expanded perlite, may be free of cement. The resulting adhesive composition free of cement may be a light weight adhesive used for indoors gluing. This adhesive may be sold as a cream adhesive. 
         [0037]    In one embodiment the composition for creating an adhesive for attaching veneer may also comprise an additive for accelerating the bonding time of the adhesive, referred to hereinafter as accelerator. The accelerator may be Calcium Formate, Calcium Chloride, or any other additive that can be used for accelerating the bonding time of the adhesive. In one embodiment, the accelerator may be added to the adhesive composition at a ratio of between 5-15% of the mass of the expanded perlite. 
         [0038]    In one embodiment, the expanded perlite and all the other ingredients, mentioned above, of the proposed composition, may be mixed together in any order. 
         [0039]    In one embodiment, the powder adhesive composition may be mixed with water to create glue for gluing any synthetic or natural stone tile to any surface. In one embodiment, due to the expanded perlite&#39;s intrinsic characteristics, water may be added to the powder adhesive composition in the mass ratio of approximately 1.2:1, meaning that approximately 1.2 liter of water can be added for each 1 kg of powder. In another embodiment, water may be added to the powder adhesive composition in the mass ratio of approximately 1:1. In one embodiment, water may be added to the powder adhesive composition in the ratio of between 100-130% of the mass of the powder adhesive composition. 
         [0040]    Preferably, the expanded perlite, used in the proposed adhesive composition, has a granular size of between 0-2 mm, where the preferred density of the expanded perlite is thus between 50-115 kg/m 3 . In another embodiment, the proposed adhesive composition comprises expanded perlite having a granular size of between 2-6 mm and having thus a density of between 40-50 kg/m 3 . 
         [0041]    In one embodiment these may be the physical properties of the expanded perlite which may be used for creating a powder adhesive composition for attaching stone tiles: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 Spatial weight 
                 40-115  
                 kg/m 3   
               
             
          
           
               
                   
                 Color 
                 White 
               
               
                   
                 Refractive Index 
                 1.4-1.5 
               
               
                   
                 Granular Size 
                 From fine powder to 6 mm 
               
               
                   
                 pH 
                 7-8 
               
               
                   
                 Softening Point 
                  890-1100° C. 
               
               
                   
                 Fusion Point 
                 1280-1350° C. 
               
             
          
           
               
                   
                 Specific Heat 
                 387  
                 J/kg · K 
               
               
                   
                 Thermal Conductivity  
                 0.04  
                 W/m ·K 
               
               
                   
                   
               
             
          
         
       
     
         [0042]    In practice, the expanded perlite, used in the proposed composition, may be derived from different sources, and may have other physical properties. 
         [0043]    The use of expanded perlite instead of sand in construction compositions may also benefit the environment as the perlite is a natural and ecological substance. The use of expanded perlite instead of sand in powder adhesives or plaster may also improve the thermal and/or acoustic insulation properties of the adhesive and/or plaster due to the expanded perlite&#39;s improved thermal and/or acoustic insulation properties. 
       Examples 
       [0044]    For the sake of enablement an example is set forth with ingredients and their approximated amounts for creating a powder adhesive composition, which comprises expanded perlite, for attaching stone tiles: 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
             
               
                   
                 Perlite 
                 720  
                 g 
               
               
                   
                 White Cement 
                 6.3  
                 Kg 
               
               
                   
                 Methocel 
                 270  
                 g 
               
               
                   
                 Vinaps 5025L 
                 1.8  
                 Kg 
               
               
                   
                 poly propylene 
                 5  
                 g 
               
               
                   
                   
               
             
          
         
       
     
         [0045]    By mixing the exemplified ingredients and amounts, of table 2, it is possible to create a powder adhesive composition of about 9 kg. Water may be added to this powder adhesive composition before gluing the stone veneer. In this example at least 9 liters of water may be added to this composition for creating glue for gluing a stone veneer. In one embodiment, upon adding water to the adhesive composition the resulting glue may be used for gluing tiles to a surface after which the glue may be dried and the tiles may stay attached to the surface henceforth. 
         [0046]    Lab tests of the above disclosed example powder adhesive composition reveal the following characteristics of the composition: 
         [0000]    
       
         
               
               
               
             
               
               
             
               
               
               
             
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
             
             
               
                 Density 
                 500 
                 kg/m 3   
               
             
          
           
               
                 Preferred Water to powder relation 
                 1 liter water for 1 kg powder 
               
             
          
           
               
                 Effective work time 
                 90 
                 minutes 
               
               
                 Open time 
                 45 
                 minutes 
               
             
          
           
               
                 Cover capability 
                 2.6 Kg/m 2  for 5 mm thickness 
               
               
                 adhesion strength after 28 days 
                 1.5 megapascal MPa 
               
               
                 Working temperature 
                 5° C.-35° C. 
               
               
                   
               
             
          
         
       
     
         [0047]    Thus, as shown in Table 3, the powder adhesive composition may weigh less than the typical prior art powder adhesive, which can reduce costs of transportation and handling. In addition, the use of expanded perlite instead of sand in powder adhesives may also prolong the open time of the adhesive, after the water is added, effectively making the perlite based adhesive more comfortable for use. 
         [0048]    While the above description discloses many embodiments and specifications of the invention, these were described by way of illustration and should not be construed as limitations on the scope of the invention. The described invention may be carried into practice with many modifications which are within the scope of the appended claims.