Substance for converting waste cooking oil into liquid soap
This application is a division of Ser. No. 056,772, filed June 2, 1987, now U.S. Pat. No. 4,792,416. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a substance for processing waste cooking oil (which may include oil and fat from either vegetable or animal sources) and in particular to a substance which allows waste cooking oil to be converted into liquid soap or detergent (including substances which may be considered to be soap in terms of chemical structure but which would not be considered to be soap in terms of such physical properties as appearance, consistency, etc.) so that the waste cooking oil can thereby be recycled for reuse safely and easily. 
     BACKGROUND OF THE INVENTION 
     In the methods of processing waste cooking oil proposed in Japanese patent laid open publications Nos. 60-44597 and 59-81398, waste cooking oil is absorbed into inorganic non water soluble substances such as activated clay, montmorillonite, sepiolite, bentonite, calcite, attapulgite, clay and so on and is then filtered for reuse. According to other known methods of processing waste cooking oil, enzyme may be applied to the waste cooking oil, or the waste cooking oil may be chemically reduced or absorbed into fibril media such as paper, non-woven fabric, rayon fibers and so on. 
     Japanese patent laid open publication No. 55-106298 discloses a method in which waste cooking oil is solidified by means of a certain higher fatty acid to form a gel which can be readily disposed of. 
     In the above mentioned prior art methods of processing waste cooking oil, since the waste cooking oil is either recycled in a form which may not be suitable for human consumption or is simply discarded, it cannot be fully utilized. There is therefore a demand for a method or a substance which will allow waste cooking oil to be recycled in the form of a reuseable substance. 
     It has been known previously that soap can be produced as a result of a (saponification) reaction between alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. or sodium orthosilicate (as proposed in Japanese patent laid open publication No. 61-116000), which is also highly alkaline, and animal fat or vegetable oil. However, such strong alkaline chemical compounds are not suitable for use at home. Alkali metal hydroxide is highly reactive with carbon dioxide and humidity in the air and could be dangerous because the reactions are often extremely violent. 
     BRIEF SUMMARY OF THE PRESENT INVENTION 
     In view of such problems of the prior art, a primary object of the present invention is to provide a substance which is capable of producing mild liquid soap from waste cooking oil which can be conveniently used for various washing purposes. In this way, not only can the waste cooking oil be reused as soap and an economic advantage obtained but also contamination of sewage with waste cooking oil can be prevented. In addition, allowing the user to produce soap from waste cooking oil will serve a beneficial educational purpose. 
     A second object of the present invention is to provide a substance for producing mild liquid soap from waste cooking oil which can eliminate peroxides from waste cooking oil in order to prevent the formation of unpleasant odorous substances. 
     A third object of the present invention is to provide a substance for producing mild liquid soap which is free from highly alkaline substances and is therefore safe to handle. 
     These and other objects of the present invention can be accomplished by providing a substance for converting waste cooking oil into liquid soap, comprising: an amine derivative and a surface-active agent; the PH value of the resulting substance being adjusted to 10 or higher. Typically, the amine derivative is a combination selected from a group including alkanol amine, alkyl (C 2  to C 18 ) amine and alkylene (C 2  to C 8 ) amine. 
     Alkanol amine soap has previously been known but it is necessary to saponify fatty acid at high temperature over a long period for formation of alkanol amine soap. On the other hand, with the substance of the present invention which is prepared by controlling the PH level and the composition, waste cooking oil which is a glycerin ester of fatty acids can be converted into mild liquid soap easily and quickly (within several tens of minutes). The obtained liquid soap, after being diluted with water, can be conveniently employed for laundry use, house cleaning, polishing furniture, dish washing and bath use. 
     According to a certain aspect of the present invention, the substance of the present invention further comprises alkali metal salt and/or alkali hydroxide, and the content of the amine derivative is greater than 50% while the content of the surface-active agent is from 0.5% to 30%. 
     According to another aspect of the present invention, the surface-active agent is a combination selected from a group including anonic agents such as LAS (linear alkylbenzenesulfonate), AOS (alphaolefinsulfonate), SAS (alkylsulfonate), AES (alkylethersulfateester), AS (alkylsulfateester), FS (alkali metal--higher fatty acid salt, or soap, in particular potassium or ammonium--alkanol amine salt), ZAS (salcosine salt) and SUS (alkylsulfosuccinate); nonionic surface-active agents such as polyoxyethylene compounds (such as polyoxyethylenealkylether, polyoxyethylenealkylphenolether, polyoxyethylene-alkylate, polyoxyethylene-fatty acid-alkanol amide, etc.), fatty acid esters (solbitanalkylate, fatty acid alkanol amide, glycerolalkylate, ethyleneglycolalkylate, etc.), alkyl phosphate esters, alkyl amine oxides, etc.; and neutral surface-active agents such as alkyl betaine, imidazoline and glycin-alkyl amine betaine. 
     When liquid soap is to be produced from, for instance, 100 grams of waste cooking oil, 20 to 50 grams of the substance of the present invention is added to the waste cooking oil and water of the same quantity (20 to 50 grams) is added thereto as required. The mixture is stirred and heated in a container made of stainless steel, steel, ceramic material, glass or alloy. The mixture then rapidly undergoes chemical reactions and turns into a yellow or orange substance in several tens of minutes. The final substance is the liquid soap. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Examples of the liquid soap produced with the substance of the present invention are described in the following. 
     
                                           TABLE 1                                 
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Various compositions of the substance of the                              
present invention                                                         
       1  2  3  4   5  6  7  8   9  10                                    
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TEA    40 80 50 70  50 20 60 10  30 --                                    
PG     20 5  20 10  10 10 5  20  20 --                                    
KOH(50%)                                                                  
       5  5  5  --  -- 5  5  5    8 5                                     
IB     5  -- 5  5   10 5  5  5   -- 5                                     
FCS    -- 5  5  2   -- 2  5  --  10 5                                     
KSi    -- -- -- --  -- 5  -- --  -- 5                                     
KSu    -- 1  1  1    5 1  -- --   2 3                                     
EDTA-k 1  -- -- --   5 -- -- 1   -- 1                                     
MEA    -- -- 10 2   10 -- -- --  -- --                                    
MIPA   -- -- -- --  -- 10 -- --  -- 10                                    
DEA    -- -- -- --  -- 5  -- 40  10 40                                    
water  balance                                                            
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 (note for Table 1)                                                       
 TEA: Triethanol amine                                                    
 PG: Propylene glycol                                                     
 IB: surfaceactive agent of coconut oil  imidazolylbetaine                
 FCS: coconut fatty acid potassium salt                                   
 KSi: potassium silicate                                                  
 Ksu: potassium succinate                                                 
 EDTA-k: Ethylene diamine tetrapotassiumeacetate                          
 MEA: Monoethanol amine                                                   
 MIPA: Monoisopropanol amine                                              
 DEA: Diethanol amine                                                     
 
    
     
                       TABLE 2                                                     
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Test results using the substance of the                                   
present invention                                                         
          I      II     III      IV   V                                   
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Composition 1 to 5                                                        
            30       20     25     25   40                                
waste cooking oil                                                         
            60       70     55     60   55                                
water       10       10     20     15    5                                
time required (min)                                                       
            15       21     18     19   11                                
Ross-Miles test                                                           
            105      95     120    110  120                               
fa %        .12      .13    .13    .12  .05                               
appearance  LY       YL     YL     YL   OR                                
smell       No       Yes    Yes    Yes  Yes                               
______________________________________                                    
 (note for Table 2)                                                       
 Compositions 1 to 5 were used in mixture ratios I to V and each mixture  
 was stirred and heated over a direct gas flame in a stainless steel      
 container. The produced soaps were light yellow to orange in color; LY   
 light yellow, YL  yellow and OR  orange. Suds formation was tested in    
 accordance with RossMiles test (JIS K3362; suds formation) by comparing  
 the heights of suds formation with that produced by 5% water solution of 
 commercially sold potassium soap (31% soap for kitchen use), the latter  
 being assinged a value of 100. fa % indicates the degree of alkalinity in
 termins of equivalent quantity of sodium hydroxide according to JIS K3304
 The smell of the product soaps ranged from none (No) to a slight oily    
 smell (Yes).                                                             
 
    
     
                       TABLE 3                                                     
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Test results using the substance of the                                   
present invention                                                         
           VI    VII     VIII    IX    X                                  
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Composition 6 to 10                                                       
             20      30      20    20    50                               
waste cooking oil                                                         
             60      55      50    75    40                               
water        20      15      30    5     10                               
time required (min)                                                       
             17      18      22    16    10                               
appearance   LY      OR      LY    YL    OR                               
oil residue (%)                                                           
             .8      1.2     0.4   1.1   .2                               
fa %         .12     .13     .13   .12   .05                              
-5° C. one week                                                    
             A       B       B     A     B                                
suds formation                                                            
             A       A       B     A     B                                
PH value     10.8    9.8     10.0  10.5  10.2                             
smell        A       B       B     A     A                                
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                       TABLE 4                                                     
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Test results using conventional substances for                            
making soap                                                               
             XI    XII     XIII     XIV                                   
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substances*    20      30      40     30                                  
waste cooking oil                                                         
               60      60      50     50                                  
water          20      10      10     20                                  
time required (min)                                                       
               X       30      15     30                                  
appearance     --      WH      YL     WH                                  
oil residue (%)                                                           
               --      0.5     0.4    2.2                                 
-5° C. one week                                                    
               --      D       C      D                                   
suds formation --      C       B      D                                   
PH value       --      12.6    11.8   11.2                                
smell          --      C       D      C                                   
______________________________________                                    
 (note for Tables 3 and 4)                                                
 *Compositions of the substances are given as follows:                    
 XI: TEA90% and PG10%                                                     
 XII: KOH10%, NaOH2%, PG15% and water73%                                  
 XIII: KOH4%, NH.sub.4 OH2%, TEA10%, PG20% and water54%                   
 XIV: MEA50%, TEA20% and water 30%                                        
 
    
     &#34;Oil residue&#34; was extracted with n-hexane for evaluation. &#34;-5° C. one week&#34; indicates the state of the soap after being left at -5° C. for one week according to the following criteria; A--very good, B--fair, C--poor and D--very poor. &#34;Suds formation&#34; is based on the impression of three monitors who tested the samples with bare hands according to the following criteria; A--very good, B--fair, C--poor and D--very poor. &#34;PH value&#34; was measured with a PH meter according to JIS Z-8802. &#34;Smell&#34; was evaluated by monitors according to the following criteria; A--almost no smell, B--slight smell, C--appreciable smell and D--unpleasant smell. The colors of the produced soaps were abbreviated as follows; LY--light yellow, YL--yellow, OR--orange and WH--white. 
     The substance of the present invention includes an amine derivative in an amount of at least 50% and a surface active-agent in an amount of 0.5% to 30% and its PH value is adjusted to 10 or higher by addition of alkali metal salt and/or alkali metal hydroxide. The substance of the present invention can be employed for laundry use, dish washing, house cleaning and bath use after being diluted with water three to five times in terms of volume. 
     The substances which can be used as the amine derivative of the present invention include alkanol amine (such as monoethanol amine, diethanol amine, triethanol amine, monoisopropanol amine and triisopropanol amine), alkyl amine (such as ethyl amine, stearyl amine, oleyl amine, polyoxyethylene palmitolein amine and lauryl amine), alkylene amine (such as ethylene diamine, diethylene triamine, propylene diamine, triethylene tetramine, aminoethyl piperazine, pentaethylene hexamine and piperazine), morpholin, hydrazine, hydroxy hydrazine, etc. In particular, alkanol (such as triethyl and diethyl) amine is preferred because of its safety, stability, smell and economy. The content of the amine derivative is preferably in the range of from 20 wt % to 98 wt % and is usually approximately 50 wt %. The content of the amine derivative should be adjusted according to the content of the surface-active agent. 
     The substances which can be used as the surface-active agent of the present invention include anonic agents such as LAS (linear alkyl benzenesulfonate), AOS (alpha-olefinsulfonate), SAS (alkylsulfonate), AES (alkylethersulfateester), AS (alkylsulfateester), FS (alkali metal--higher fatty acid salt, or soap, in particular potassium or ammonium--alkanol amine salt), ZAS (salcosine salt), SUS (alkylsulfosuccinate), etc. The nonionic surface-active agents which can be used as the surface-active agent for the substance of the present invention include polyoxyethylene compounds (such as polyoxyethylenealkylether, polyoxyethylenealkylphenolether, polyoxyethylenealkylate, polyoxyethylene-fatty acid-alkanol amide, etc.), fatty acid esters (sorbitanalkylate, fatty acid alkanol amide, glycerolalkylate, ethyleneglycolalkylate, etc.), alkylphosphate esters, alkyl amine oxides, etc Neutral surface-active agents such as alkyl betaine, imidazoline and glycin-alkyl amine betaine compounds can also be used. 
     In particular, anionic surface-active agents such as potassium or ammonium--alkanol amine salt are most preferred because of their stability in water solution and their commercial availability. Nonionic surface-active agents such as polyoxyethyleneether compounds and amine oxide compounds are also preferred because of their stability in alkaline environment and the freedom with which they can be mixed. 
     The content of the surface-active agent can be freely selected but should be preferably in the range from 0.5% to 50%. The content of the surface-active agent should be adjusted depending on the nature of the waste cooking oil that is to be processed so that the saponification, suds formation and alkalinity control will be satisfactory. When the surface-active agent content exceeds 50%, this can be compensated for either by increasing the alkalinity of the substance of the present invention or by using a greater amount of the substance of the present invention with a given amount of waste cooking oil, but the stability of the substance may be impaired and the economic benefits may suffer. 
     In addition to the amine derivative and the surface-active agent, the substance of the present invention may include alkali metal salt and/or alkali hydroxide which serves as an agent for raising the PH value of the substance to 10 or higher, stabilizing the alkaline contents and improving the washing performance of the produced soap. 
     The alkali metal salt may be any of the following substances; potassium bicarbonate, potassium carbonate, sodium carbonate, potassium silicate, potassium orthosilicate, potassium metasilicate, potassium pyrophosphate, potassium tertiary phosphate, potassium hexametaphosphate, potassium citrate, ammonium citrate, potassium malate, ammonium malate, ammonium oxalate, potassium oxalate, potassium maleate, ammonium maleate, potassium tartrate, ammonium tartrate, Rochelle salt, ammonium phytate, potassium phytate, ammonium glycolate, tetrasodium ethylenediamine tetraacetate, tetrapotassium ethylenediamine tetraacetate, potassium nitrile triacetate, etc. 
     The alkali metal hydroxide may be potassium hydroxide, ammonium hdyroxide, sodium hydroxide, lithium hydroxide, or a combination thereof, and potassium hydroxide is most preferred. 
     The following is a typical composition of the substance of the present invention: 
     amine derivative 20 to 90 wt % 
     surface-active agent 0.5 to 30 wt % 
     other balancing agents balance 
     It is necessary for the PH value of the substance to be 10 or higher (preferably in the range from 10 to 13.5) for the purpose of achieving satisfactory saponification and formation of a safe salt by causing thorough reaction between glyceride and peroxide of the waste cooking oil and water. If the PH value is lower than 10, saponification will be insufficient and the object of the present invention will not be satisfactorily achieved. The content of sodium hydroxide and ammonium hydroxide in the above mentioned balancing agents is desired to be less than 5% for safety in handling. 
     Optional components which may be added to the substance of the present invention include dispersing agents (such as urea, sodium xylenesulfonate, potassium cumenesulfonate, ethyleneglycol, lower alcohols, glycolether, ethyleneurea, etc.), anti-oxidization agents (such as BHT, tocopherol, lipoid, etc.), perfume bases and vegetable essences for masking oil odor (such as limonene, terpenoid, alpha-pinene, etc.), water-soluble colloid (colloidal silica, colloidal alumina, colloidal sulfur, etc.), deodorizing and sterilizing agents (such as sodium hypochlorite, chlorine dioxide, sodium bromite, etc.), and coloring agents (dyes, pigments, fluorescent agents, etc.), etc. 
     The substance of the present invention may have different levels of consistency and may be in the form of a liquid, a paste or semi-solid. However, the liquid state is preferred because of its convenience in handling. 
     Thus, according to the present invention, liquid soap can be made from waste cooking oil safely and easily as a result of a mild alkaline chemical reaction. Therefore, not only can the contamination of sewage with waste cooking oil be prevented but also economic advantages can be obtained through conversion of waste material into useable soap. Furthermore, since the obtained soap is more or less liquidous, it is easier to handle than solid soap and its level of concentration can be adjusted by adding water thereto in-a desired amount for different soap applications.