Abstract:
Compositions with sodium carboxymethylcellulose and hydroxyethyl cellulose are provided for environmentally safe disposal of water-based latex and acrylic formulations. Improved methods for environmentally safe disposal of water-based latex and acrylic formulations are provided as well.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention provides waste paint solidifying compositions and methods for environmentally-friendly paint disposal. The waste paint solidifying compositions are fast-acting and comprise sodium carboxymethylcellulose as a chemical thickener to solidify latex or acrylic paint. The compositions can be used to treat water-based waste streams such as paints, textures, joint compounds, and coatings for disposal in accordance with applicable environmental and government regulations. Methods for non-toxic disposal of latex or acrylic paint are provided as well. 
       BACKGROUND 
       [0002]    Extrapolating data from several states, the U.S. Environmental Protection Agency (EPA) calculates that between 35 and 103 million gallons of paint are disposed of each year. While the EPA does not classify latex paint as hazardous waste, most waste disposal facilities will not accept paint of any kind unless the paint is completely solidified. Liquid latex paint can cause huge cleanup problems such as contamination of ground water or when cans with liquid paint are crushed during transportation to a landfield and the paint leaks out onto roadways. 
         [0003]    Construction industry utilizes liquid latex and acrylic paints and various water-based latex and acrylic products such as, for example, as water-based coatings, primers, textures and joint compounds. However, these products may not be disposed of as liquids. One solution for proper disposal is to solidify waste paints by adding an absorbent material. 
         [0004]    Many commercially available solidifiers use sodium polyacrylate crystals to dispose of water-based paints and colorants. For example, US patent publication 2002/0147378 discloses the use of a swellable polyacrylate to solidify liquid paints. Other known paint solidifiers use pelletized corn cobs, or absorbents like clay, sand, or vermiculite and include solidifiers disclosed in US patent publication 2012/0073470. However, many of these solidifiers take several hours to absorb a liquid paint and some solidifiers need to be used in large amounts, which increases dramatically the amount of waste generated. Thus, there remains the need for non-toxic paint solidifiers which can solidify expeditiously acrylic and latex liquid paints without increasing significantly the amount of solid waste generated in the process. 
       SUMMARY OF THE INVENTION 
       [0005]    At least some of these needs are addressed by compositions and methods of the present invention. One embodiment provides a waste paint solidifying composition formulated with sodium carboxymethylcellulose and hydroxyethyl cellulose. The waste paint solidifying composition may further comprise cellulosic fibers, an absorbent or a combination thereof. Various cellulosic fibers are suitable including, but not limited to, straw, rice hulks, wood chips, corn cobs or any combination thereof. 
         [0006]    In some embodiments, an absorbent may be sand, attapulgite clay and vermiculite clay. Suitable waste paint solidifying compositions include those with 30-50% sodium carboxymethylcellulose, 10-30% hydroxyethyl cellulose, 10-30% cellulosic fibers and 10-30% attapulgite clay. 
         [0007]    Further embodiments provide methods for environmentally safe disposal of waste water-based paint products in which the waste products are mixed with a waste paint solidifying composition comprising sodium carboxymethylcellulose and hydroxyethyl cellulose. These methods are useful for disposing of various waste water-based paint products including, but not limited to, water-based latex paints, polyacrylic paints, joint compounds and coatings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIGS. 1A ,  1 B and  1 C depict solidification of a latex paint as described in Table 1; 
           [0009]      FIGS. 2A ,  2 B,  2 C and  2 D depict solidification of SHEETROCK® MH Speed-Tex Ready™ mixed spray texture as described in Table 2; and 
           [0010]      FIGS. 3A ,  3 B,  3 C and  3 D depict solidification of SHEETROCK® wall &amp; ceiling spray texture, sand finish texture  12  as described in Table 3. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    The present invention provides waste paint solidifying compositions comprising at least one cellulosic thickener. These waste paint solidifying compositions are suitable for solidifying water-based waste latex paint, acrylic paint, stains, primers, coatings, texture, joint compounds and other non-hazardous water-based products to a non-flowable, gel-like consistency. The waste paint solidifying compositions provide an environmentally acceptable way for disposing of unwanted liquid paint products by curbside garbage disposal in accordance with municipal landfill regulations. 
         [0012]    One embodiment provides a waste paint solidifying composition which comprises a combination of sodium carboxymethylcellulose and hydroxyethyl cellulose. At least in some embodiments, a waste paint solidifying composition comprises 30-50% of sodium carboxymethylcellulose. At least in some embodiments, a waste paint solidifying composition comprises 10-30% of hydroxyethyl cellulose. At least in some embodiments, a waste paint solidifying composition comprises 30-50% of sodium carboxymethylcellulose and 10-30% of hydroxyethyl cellulose. Some waste paint solidifying compositions comprise about 40% of sodium carboxymethylcellulose and about 20% of hydroxyethyl cellulose. 
         [0013]    In addition to sodium carboxymethylcellulose and hydroxyethyl cellulose, some waste paint solidifying compositions may comprise cellulosic fibers. At least in some embodiments, waste paint solidifying compositions comprise 10-30% cellulosic fibers. In some embodiments, waste paint solidifying compositions comprise 20% cellulosic fibers. Various cellulosic fibers can be used, including, but not limited to, straw, rice hulks, wood chips and corn cobs. 
         [0014]    Waste paint solidifying compositions may further comprise an absorbent. Suitable absorbents include, but are not limited to, clay, sand, attapulgite clay and vermiculite clay. In some embodiments, a waste paint solidifying composition may comprise 10-30% of an absorbent. In further embodiments, a waste paint solidifying composition may comprise 20% of an absorbent. Some waste paint solidifying compositions comprise 20% attapulgite clay. 
         [0015]    Some waste paint solidifying compositions comprise sodium carboxymethylcellulose, hydroxyethyl cellulose, cellulosic fibers and attapulgite clay. Some waste paint solidifying compositions comprise 30-50% sodium carboxymethylcellulose, 10-30% hydroxyethyl cellulose, 10-30% cellulosic fibers and 10-30% attapulgite clay. Some waste paint solidifying compositions comprise 40% sodium carboxymethylcellulose, 20% hydroxyethyl cellulose, 20% cellulosic fibers and 20% attapulgite clay. 
         [0016]    Waste paint solidifying compositions can be prepared by using various methods known to a person of skill, including by dry blending sodium carboxymethylcellulose and hydroxyethyl cellulose thickeners with at least one absorbent filler such as cellulosic fibers and attapulgite clay. 
         [0017]    In order to gel-solidify acrylic or latex liquid waste substance, a waste paint solidifying composition is added to the substance, stirred or drill mixed with the substance and the mixture is allowed to hydrate to a solidified state. Typically, a waste paint solidifying composition can be added in the amount from 1% to 5% by weight of acrylic or latex liquid to be solidified. In some embodiments, a waste paint solidifying composition can be added in the amount from 1% to 10% by weight of acrylic or latex liquid to be solidified. 
         [0018]    In some embodiments, a waste paint solidifying composition comprising 30-50% of sodium carboxymethylcellulose and 10-30% hydroxyethyl cellulose is added in the amount from 1% to 5% by weight of acrylic or latex liquid to be solidified. In some embodiments, a waste paint solidifying composition comprising 30-50% of sodium carboxymethylcellulose, 10-30% hydroxyethyl cellulose, 10-30% cellulosic fibers and 10-30% attapulgite clay, is added in the amount from 1% to 5% by weight of acrylic or latex liquid to be solidified. In some embodiments, a waste paint solidifying composition comprising 30-50% of sodium carboxymethylcellulose and 10-30% hydroxyethyl cellulose is added in the amount from 1% to 5% by weight of acrylic or latex liquid to be solidified. In some embodiments, a waste paint solidifying composition comprising 30-50% of sodium carboxymethylcellulose, 10-30% hydroxyethyl cellulose, 10-30% cellulosic fibers and 10-30% attapulgite clay, is added in the amount from 1% to 10% by weight of acrylic or latex liquid to be solidified. 
         [0019]    The inventors have unexpectedly discovered that a waste paint solidifying composition comprising sodium carboxymethylcellulose and hydroxyethyl cellulose thickeners is highly efficient in gel solidifying acryl and latex aqueous products. The waste paint solidifying composition solidifies various latex and acrylic waste streams when used in the amount of as little as 1%-3% by weight of waste liquid to be solidified. Further and also unexpectedly, a waste paint solidifying composition is fast acting and changes consistency of acrylic or latex liquid from liquid to non-flowable gel in a short to period time ranging from several seconds to 10 minutes. A non-toxic formulation of the waste paint solidifying composition and its ability to solidify a waste paint product rapidly provide a significant improvement over commercially available waste solidifying products comprising a polyacrylate or corn cobs. 
         [0020]    A gel-solidifying reaction with the present waste paint solidifying composition is irreversible and gel-solidified waste paint does not convert back to a fluid state even after it comes in contact with water or other liquid at a landfill. 
         [0021]    Further embodiments provide methods in which water-based latex or acrylic products are gel solidified in a period of time less than one hour by using a waste paint solidifying composition comprising sodium carboxymethylcellulose and hydroxyethyl cellulose thickeners. 
         [0022]    As shown in Table 1 and corresponding  FIGS. 1A-1C , waste water-based latex paint is gel-solidified with a waste paint solidifying composition in a matter of 10 minutes when a waste paint solidifying composition comprising 40% sodium carboxymethylcellulose, 20% hydroxyethyl cellulose, 20% cellulosic fibers and 20% attapulgite clay, is added to the final concentration of 3% by weight of waste latex paint. 
         [0023]    In comparison, a commercially available polyacrylate-based solidifier gel-solidifies the same amount of latex paint only in about 25 minutes. Compare Table 1, column 1 with column 2 and also  FIG. 1A  with  FIG. 1B . A commercially available corncob-based solidifier gel-solidifies the same amount of latex paint in more than 4 hours and it has to be used in a much larger amount (13.51%). Compare column 1 with column 3 in Table 1 and also  FIG. 1A  with  FIG. 1C . 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Comparative Gel-Solidification of Waste Latex Paint 
               
             
          
           
               
                   
                 1 
                 2 
                 3 
               
               
                   
                   
               
             
          
           
               
                 Amount of 
                 500 
                 grams 
                 500 
                 grams 
                 500 
                 grams 
               
               
                 Latex Water- 
               
               
                 Based Paint 
               
               
                 with density 
               
               
                 10.65 lb/ 
               
               
                 gallon 
               
             
          
           
               
                 Waste Paint 
                 Sodium 
                 Commercial 
                 Commercial 
               
               
                 Solidifier 
                 Carboxymethylcellulose; 
                 polyacrylate- 
                 corncob- 
               
               
                   
                 Hydroxyethyl Cellulose 
                 based 
                 based 
               
               
                   
                 Cellulosic Fibers 
                 solidifier 
                 solidifier 
               
               
                   
                 Attapulgite Clay 
               
             
          
           
               
                 Amount of 
                 15 
                 grams 
                 15 
                 grams 
                 67.55 
                 grams 
               
               
                 Solidifier 
               
             
          
           
               
                 Percent by 
                 3% 
                 3% 
                 13.51% 
               
               
                 Weight 
               
             
          
           
               
                 Hand Mix 
                 2 
                 minutes 
                 2 
                 minutes 
                 2 
                 minutes 
               
               
                 Time 
               
               
                 Gel Time 
                 10 
                 minutes 
                 25 
                 minutes 
                 +4 
                 hours 
               
             
          
           
               
                 FIG. 
                 FIG. 1A 
                 FIG. 1B 
                 FIG. 1C 
               
               
                   
               
             
          
         
       
     
         [0024]    As shown in Table 2 and corresponding  FIGS. 2A-2D , a waste paint solidifying composition comprising sodium carboxymethylcellulose, hydroxyethyl cellulose, cellulosic fibers and attapulgite clay is also more efficient in solidifying aqueous acrylic formulation SHEETROCK® Brand MH SPEED-TEX™ Ready-Mixed Spray Texture (United States Gypsum Company, Illinois). 
         [0025]    Specifically, a waste paint solidifying composition comprising 40% sodium carboxymethylcellulose, 20% hydroxyethyl cellulose, 20% cellulosic fibers and 20% attapulgite clay gel-solidified the texture in 30 seconds when used at 2% by weight of the texture and in 1 minute when used at 1%. Compare columns 1 and 3 in Table 2 and  FIGS. 2A and 2C . A commercially available polyacrylate-based solidifier is less efficient and gel-solidifies the same amount of SPEED-TEX™ in 2 minutes when used at 2% and in 7 minutes when used at 1%. Compare column 1 with column 2 in Table 2 and column 3 with column 4 in Table 2; also compare  FIG. 2A  with  FIG. 2B  and  FIG. 2C  with  FIG. 2D . 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Comparative Gel-Solidification of SPEED-TEX ™ 
               
             
          
           
               
                   
                 1 
                 2 
                 3 
                 4 
               
               
                   
                   
               
             
          
           
               
                 Amount of 
                 500 
                 grams 
                 500 
                 grams 
                 500 
                 grams 
                 500 
                 grams 
               
               
                 Speed-Tex 
               
             
          
           
               
                 Waste Paint 
                 Sodium Carboxymethyl 
                 Commercial 
                 Sodium Carboxymethyl 
                 Commercial 
               
               
                 Solidifier 
                 cellulose; Hydroxyethyl 
                 polyacrylate- 
                 cellulose; Hydroxyethyl 
                 polyacrylate- 
               
               
                   
                 Cellulose; Cellulosic 
                 based 
                 Cellulose; Cellulosic 
                 based solidifier 
               
               
                   
                 Fibers; Attapulgite Clay 
                 solidifier 
                 Fibers; Attapulgite Clay 
               
             
          
           
               
                 Amount of 
                 10 
                 grams 
                 10 
                 grams 
                 5 
                 grams 
                 5 
                 grams 
               
               
                 Solidifier 
               
             
          
           
               
                 Percent by 
                 2% 
                 2% 
                 1% 
                 1% 
               
               
                 Weight 
               
             
          
           
               
                 Mix Time 
                 20 
                 seconds 
                 2 
                 minutes 
                 45 
                 seconds 
                 2 
                 minutes 
               
               
                 Gel Time 
                 30 
                 seconds 
                 5 
                 minutes 
                 1 
                 minute 
                 7 
                 minutes 
               
             
          
           
               
                 FIG. 
                 FIG. 2A 
                 FIG. 2B 
                 FIG. 2C 
                 FIG. 2D 
               
               
                   
               
             
          
         
       
     
         [0026]    As shown in Table 3 and corresponding  FIGS. 3A-3D , a waste paint solidifying composition comprising sodium carboxymethylcellulose, hydroxyethyl cellulose, cellulosic fibers and attapulgite clay is also efficient in solidifying aqueous acrylic formulation SHEETROCK® Wall &amp; Ceiling Spray Texture, sand finish texture  12  (United States Gypsum Company, Illinois). 
         [0027]    Specifically, a waste paint solidifying composition comprising 30% sodium carboxymethylcellulose, 40% hydroxyethyl cellulose, 20% cellulosic fibers and 20% attapulgite clay gel-solidifies the texture in 1 minute when used at 2% by weight of the texture and in 2 minutes when used at 1% by weight of the texture. Compare Table 3, columns 1 and 3 and  FIGS. 3A and 3C . In comparison, a commercially available polyacrylate-based solidifier gel-solidifies the same amount of Texture XII in 4 minutes when used at 2% by weight of the texture and in 11 minutes when used at 1% by weight of the texture. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Comparative Gel-Solidification of Texture XII 
               
             
          
           
               
                   
                 1 
                 2 
                 3 
                 4 
               
               
                   
                   
               
             
          
           
               
                 Amount of 
                 500 
                 grams 
                 500 
                 grams 
                 500 
                 grams 
                 500 
                 grams 
               
               
                 Texture XII 
               
             
          
           
               
                 Waste Paint 
                 Sodium Carboxymethyl 
                 Commercial 
                 Sodium Carboxymethyl 
                 Commercial 
               
               
                 Solidifier 
                 cellulose; Hydroxyethyl 
                 polyacrylate- 
                 cellulose; Hydroxyethyl 
                 polyacrylate- 
               
               
                   
                 Cellulose; Cellulosic 
                 based 
                 Cellulose; Cellulosic 
                 based solidifier 
               
               
                   
                 Fibers; Attapulgite Clay 
                 solidifier 
                 Fibers; Attapulgite Clay 
               
             
          
           
               
                 Amount of 
                 10 
                 grams 
                 10 
                 grams 
                 5 
                 grams 
                 5 
                 grams 
               
               
                 Solidifier 
               
             
          
           
               
                 Percent by 
                 2% 
                 2% 
                 1% 
                 1% 
               
               
                 Weight 
               
             
          
           
               
                 Mix Time 
                 45 
                 seconds 
                 2 
                 minutes 
                 45 
                 seconds 
                 2 
                 minutes 
               
               
                 Gel Time 
                 1 
                 minute 
                 4 
                 minutes 
                 2 
                 minutes 
                 11 
                 minutes 
               
             
          
           
               
                 FIG. 
                 FIG. 3A 
                 FIG. 3B 
                 FIG. 3C 
                 FIG. 3D 
               
               
                   
               
             
          
         
       
     
         [0028]    As shown in Tables 1, 2 and 3, a waste paint solidifying composition comprising sodium carboxymethylcellulose, hydroxyethyl cellulose, cellulosic fibers and attapulgite clay gel solidifies water-based latex and acrylic waste products in a matter of minutes. The reaction is irreversible and once solidified, the waste products can be safely disposed of. Only a small amount of the waste paint solidifying composition, typically less than 10%, is needed to gel solidify the waste product. Thus, this gel solidification method does not increase significantly the total volume of waste. 
       Example 1 
       [0029]    A waste paint solidifying composition was prepared by mixing together the following: 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Sodium Carboxymethylcellulose 
                 40% 
               
               
                   
                 Hydroxyethyl Cellulose 
                 20% 
               
               
                   
                 Cellulosic Fibers 
                 20% 
               
               
                   
                 Attapulgite Clay 
                 20% 
               
               
                   
                   
               
               
                   
                 All percentages are by weight. 
               
             
          
         
       
     
       Example 2 
       [0030]    The waste paint solidifying composition of Example 1 was used to solidify a water-based latex paint as shown in Table 1 and  FIGS. 1A ,  1 B and  1 C. The waste paint solidifying composition of Example 1 was also used to solidify an aqueous acrylic product as shown in Table 2 and  FIGS. 2A ,  2 B,  2 C and  2 D and in Table 3 and  FIGS. 3A ,  3 B,  3 C and  3 D. 
         [0031]    In all tests, the waste paint solidifying composition was stirred into the waste liquids by hand using a spatula. Gel time was measured as the amount of time required for developing a sufficient level of viscosity needed to prevent the waste material from falling out of the quart cup when completely inverted. Gel time was measured from the start of the test when the waste paint solidifying composition was introduced into the waste stream. 
         [0032]    While particular embodiments of the waste paint solidifying composition and methods of using the composition have been shown and described, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.