Patent Publication Number: US-2022220363-A1

Title: Co-surfactant, surfactant composition, and composition for oil recovery

Description:
TECHNICAL FIELD 
     The present invention relates to a co-surfactant, and a surfactant composition and a composition for oil recovery containing the co-surfactant. 
     BACKGROUND ART 
     For the purpose of, for example, improving detergency and foaming, a co-surfactant may be added to a detergent composition together with a surfactant. 
     For example, Patent Document 1 discloses a cleaning composition including an anionic surfactant and a co-surfactant, in which the co-surfactant is selected from the group consisting of an amine oxide surfactant, a zwitterionic surfactant, and a mixture thereof. 
     PRIOR ART DOCUMENTS 
     Patent Document 
     Patent Document 1: JP-A-2019-6998 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     The present invention provides a co-surfactant which can be used together with a surfactant to improve functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. The present invention also provides a surfactant composition and a composition for oil recovery containing a surfactant and the co-surfactant. 
     Means for Solving the Problems 
     As a result of intensive studies, the present inventor has found that the above problems can be solved by the following co-surfactant. 
     The present invention relates to a co-surfactant comprising at least one kind of a compound represented by a Chemical Formula (1): 
     
       
         
         
             
             
         
       
     
     wherein R 1  is a hydrogen atom or an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, R 2  is an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, a total number of carbon atoms of R 1  and R 2  is 6 or more and 34 or less, X is a single bond or an aliphatic hydrocarbon group having 1 or more and 5 or less carbon atoms, and one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH or —O—CH(—CH 2 —OH) 2 . 
     EFFECT OF THE INVENTION 
     When the co-surfactant is used together with a surfactant, the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability can be improved. Accordingly, when the co-surfactant of the present invention is used, a microemulsion having excellent detergency and micelle stability can be obtained. 
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, a detailed described is made of the present invention. 
     Co-Surfactant 
     In the present invention, a co-surfactant is an agent used together with a surfactant, and is preferably an auxiliary agent for improving the function (effect) of the surfactant. The co-surfactant of the present invention contains at least one kind of a compound represented by the following Chemical Formula (1). In addition, the co-surfactant of the present invention may be composed of a compound represented by the following Chemical Formula (1). In addition, the co-surfactant of the present invention may be composed of one or more kinds of a compound represented by the following Chemical Formula (1). 
     
       
         
         
             
             
         
       
     
     (In Chemical Formula (1), R 1  is a hydrogen atom or an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, R 2  is an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, a total number of carbon atoms of R 1  and R 2  is 6 or more and 34 or less, X is a single bond or an aliphatic hydrocarbon group having 1 or more and 5 or less carbon atoms, and one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH or —O—CH(—CH 2 —OH) 2 .) 
     R 1  is a hydrogen atom or an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, or from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, preferably an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms. R 2  is an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms. Each of the aliphatic hydrocarbon groups of R 1  and R 2  is preferably a linear alkyl group or a branched alkyl group (also referred to as a branched chain alkyl group), more preferably a linear alkyl group. Each of the aliphatic hydrocarbon groups of R 1  and R 2  may have a substituent such as a halogen group, a hydroxy group, a ketone group, a carboxyl group, an aryl group, or an alkoxy group as long as the effect of the present invention is not impaired. R 1  and R 2  may be the same aliphatic hydrocarbon groups as each other or different aliphatic hydrocarbon groups from each other. In addition, the total number of substituents of R 1  and R 2  is preferably 5 or less, more preferably 3 or less, further preferably 1 or less, still more preferably 0 (that is, having no substituent) from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. 
     The total number of carbon atoms of R 1  and R 2  is 6 or more and 34 or less, or from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, preferably 8 or more, more preferably 10 or more, further preferably 12 or more, still more preferably 14 or more, and preferably 26 or less, more preferably 22 or less, further preferably 18 or less, still more preferably 16 or less. 
     X is a single bond or an aliphatic hydrocarbon group having 1 or more and 5 or less carbon atoms, or from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, preferably a single bond or an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms, more preferably a single bond or an aliphatic hydrocarbon group having 1 or more and 2 or less carbon atoms, further preferably a single bond or an aliphatic hydrocarbon group having 1 carbon atom, still more preferably a single bond. 
     The total number of carbon atoms of R 1 , R 2  and X is 6 or more and 39 or less, or from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, preferably 8 or more, more preferably 10 or more, further preferably 12 or more, still more preferably 14 or more, and preferably 31 or less, more preferably 28 or less, further preferably 26 or less, still more preferably 25 or less, still more preferably 24 or less, still more preferably 22 or less, still more preferably 20 or less, still more preferably 18 or less, still more preferably 16 or less. 
     When X is the aliphatic hydrocarbon group, X is preferably a linear alkyl group or branched alkyl group, more preferably a linear alkyl group from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, X is preferably 
     *—(CH 2 ) n —* (n is 0 or more and 5 or less, and * represents a binding site), 
     wherein n is preferably 0 or more, preferably 3 or less, more preferably 2 or less, further preferably 1 or less, still more preferably 0, that is, a single bond. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant preferably contains two or more kinds of the compound, between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant preferably contains two or more kinds of the compound, between which the total numbers of carbon atoms of R 1 , R 2  and X are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant preferably contains two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant preferably contains two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms, and between which the total numbers of carbon atoms of R 1 , R 2  and X are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant preferably contains two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 2 or less carbon atoms, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant preferably contains two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 2 or less carbon atoms, and between which the total numbers of carbon atoms of R 1 , R 2  and X are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant more preferably contains two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 carbon atom, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant more preferably contains two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 carbon atom, and between which the total numbers of carbon atoms of R 1 , R 2  and X are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     From the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability, the co-surfactant still more preferably contains two or more kinds of the compound in which X is a single bond, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     When the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 12, a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is preferably 75 mass % or more, more preferably 85 mass % or more, further preferably 95 mass % or more, still more preferably 100 mass % from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. 
     When the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is preferably 75 mass % or more, more preferably 85 mass % or more, further preferably 95 mass % or more, still more preferably 99 mass % or more, still more preferably 100 mass % from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. 
     When the co-surfactant contains two or more kinds of the compound represented by the Chemical Formula (1) between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different, the content ratio of the compound in which the number of carbon atoms of R 1  is 5 or more and the number of carbon atoms of R 2  is 5 or more is preferably 10 mass % or more, more preferably 20 mass % or more, further preferably 30 mass % or more, and preferably 90 mass % or less, more preferably 80 mass % or less, further preferably 70 mass % or less from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. 
     The method for producing the compound represented by the Chemical Formula (1) is not particularly limited. For example, the compound can be produced by oxidizing the double bond in an internal or terminal olefin with a peroxide such as hydrogen peroxide, performic acid, or peracetic acid to synthesize an internal or terminal epoxide, and reacting the obtained internal or terminal epoxide with glycerin. In the case of a mixture in which the total numbers of carbon atoms of internal or terminal olefins are constant but the double bonds are present at different positions, the compound represented by the Chemical Formula (1) obtained by the above producing method is a mixture of a plurality of compounds in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. The compound represented by the Chemical Formula (1) obtained by the above producing method is usually a mixture of a compound 1 in which one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH (hereinafter, also referred to as ether alcohol 1) and a compound 2 in which one of A 1  and A 2  is —OH and the other is —O—CH(—CH 2 —OH) 2  (hereinafter, also referred to as ether alcohol 2). 
     The internal olefin used for the production of the compound represented by the Chemical Formula (1) may contain a terminal olefin. In this case, the content of terminal olefin contained in olefin is, for example, 0.1 mass % or more, 0.2 mass % or more, and 5 mass % or less, 3 mass % or less, 2 mass % or less, 1 mass % or less, 0.5 mass % or less. 
     When the co-surfactant contains the ether alcohol 1 and the ether alcohol 2, the content of the ether alcohol 1 is preferably 1 mass % or more, more preferably 30 mass % or more, further preferably 40 mass % or more, still more preferably 50 mass % or more, and preferably 99 mass % or less, more preferably 90 mass % or less, further preferably 80 mass % or less with respect to the total amount of the ether alcohol 1 and the ether alcohol 2, from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. From the same viewpoint, the content is preferably 1 to 99 mass %, more preferably 30 to 99 mass %, further preferably 40 to 90 mass %, still more preferably 50 to 80 mass %. 
     The co-surfactant can be obtained as one kind of the compound represented by the Chemical Formula (1), a mixture of two or more kinds of the compound represented by the Chemical Formula (1), or a mixture of the above compound and a trace component other than olefin contained in the raw material olefin and a derivative thereof. 
     Surfactant Composition 
     The surfactant composition of the present invention contains at least a surfactant (except the co-surfactant.) and the co-surfactant. 
     The surfactant is not particularly limited, and examples thereof include an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and a cationic surfactant. These may be used alone or in combination of two or more kinds thereof. 
     Examples of the anionic surfactant include sulfuric acid ester salts such as alkyl sulfate, alkenyl sulfate, polyoxyalkylene alkyl ether sulfate, polyoxyalkylene alkenyl ether sulfate, and polyoxyalkylene alkyl phenyl ether sulfate; sulfonates such as sulfosuccinic acid alkyl ester salt, polyoxyalkylene sulfosuccinic acid alkyl ester salt, alkanesulfonate, hydroxyalkanesulfonate, alkenesulfonate, acyl isethionate, and acyl methyl taurate; higher fatty acid salts having 8 to 24 carbon atoms; phosphate ester salts such as alkyl phosphate and polyoxyalkylene alkyl ether phosphate; and amino acid salts such as acyl glutamate, alanine derivatives, glycine derivatives, and arginine derivatives. Examples of these salts include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; and ammonium salts. These may be used alone or in combination of two or more kinds thereof. 
     Examples of the nonionic surfactant include polyethylene glycol kind surfactants such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylphenyl ether, and polyoxyalkylene (cured) castor oil; polyhydric alcohol kinds such as sucrose fatty acid ester, polyglycerol alkyl ether, polyglycerol fatty acid ester, alkyl glycoside, and acylated alkyl glucamide; and fatty acid alkanolamides. Specific examples thereof include fatty acid monoalkanolamides such as coconut oil fatty acid monoethanolamide and coconut oil fatty acid N-methyl monoethanolamide. These may be used alone or in combination of two or more kinds thereof. 
     Examples of the amphoteric surfactant include betaine-based surfactants such as imidazoline-based betaine, alkyldimethylaminoacetic acid betaine, fatty acid amidopropyl betaine, and sulfobetaine; amine oxide kind surfactants such as alkyldimethylamine oxide. Specific examples thereof include coconut oil fatty acid amidopropyl dimethylcarbobetaine, lauramidopropyl dimethylcarbobetaine, laurylcarboxymethyl hydroxyimidazolium betaine, lauryldimethylaminoacetic acid betaine, and laurylhydroxysulfobetaine. These may be used alone or in combination of two or more kinds thereof. 
     Examples of the cationic surfactant include quaternary ammonium salts having a hydrocarbon group having 12 or more and 28 or less carbon atoms which may be divided by an amide group, an ester group, or an ether group; pyridinium salts; and salts of mineral acid or organic acid of tertiary amine. Specific examples include mono-long chain alkyl trimethyl ammonium salts such as octyl trimethyl ammonium salt, decyl trimethyl ammonium salt, lauryl trimethyl ammonium salt, myristyl trimethyl ammonium salt, cetyl trimethyl ammonium salt, stearyl trimethyl ammonium salt, behenyl trimethyl ammonium salt, and octadecyloxypropyl trimethyl ammonium salt; di-long chain alkyldimethylammonium salts such as dioctyldimethylammonium salt, didecyldimethylammonium salt, dilauryldimethylammonium salt, dimyristyldimethylammonium salt, dicetyldimethylammonium salt, distearyldimethylammonium salt, and diisotetradecyldimethylammonium salt; and hydrochlorides, citrates, or lactates of mono-long chain alkyldimethylamine such as stearyldimethylamine, behenyldimethylamine, octadecyloxypropyldimethylamine, or dimethylaminopropylstearic acid amide. The ammonium salts may be halogen salts such as ammonium chloride, bromide, or iodide. These may be used alone or in combination of two or more kinds thereof. 
     The surfactants are preferably an ionic or nonionic surfactant from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability with the co-surfactant, more preferably a nonionic surfactant from the viewpoint of microemulsion forming ability, or more preferably an ionic surfactant from the viewpoint of an auxiliary effect described below. 
     The content of the surfactant in the surfactant composition is not particularly limited, but is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, further preferably 1 mass % or more, and preferably 80 mass % or less, more preferably 50 mass % or less, further preferably 30 mass % or less from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability with the co-surfactant. 
     The content of the co-surfactant in the surfactant composition is not particularly limited, but is preferably 10 mass % or more, more preferably 20 mass % or more, further preferably 30 mass % or more, and preferably 90 mass % or less, more preferably 70 mass % or less, further preferably 50 mass % or less with respect to the total content of the surfactant and the co-surfactant from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. 
     The surfactant composition of the present invention may optionally contain a component or the like for use in a detergent such as a solvent, a perfume, a dye, a preservative, a moisturizing agent, an antibacterial agent, an anti-dandruff agent, a pearling agent, a vitamin agent, a thickener, a pH adjuster, a bleaching agent, a chelating agent, a water-soluble salt or an oil agent as long as the effect of the present invention is not impaired. 
     The surfactant composition of the present invention can contain a solvent for the purpose of, for example, improving low-temperature stability and washing performance. Examples of the solvent include alcohols, glycol ethers, and alkylene glycol alkyl ethers. Examples of the alcohol include monohydric alcohols such as ethanol, isopropyl alcohol, and butanol, polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol (2-methyl-2, 4-pentanediol), 1,5-pentanediol, 1,6-hexanediol, and glycerin, and aromatic alcohols such as benzyl alcohol. Examples of the alkylene glycol ether include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Examples of the alkylene glycol alkyl ether include diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, 1-methoxy-2 propanol and 1-ethoxy-2-propanol, 2-phenoxyethanol, diethylene glycol monophenyl ether, and triethylene glycol monophenyl ether. These may be used alone or in combination of two or more kinds thereof. 
     In the present invention, the content of the solvent in the surfactant composition is preferably 30 mass % or less, more preferably 20 mass % or less, further preferably 10 mass % or less, still more preferably 5 mass % or less, still more preferably 1 mass % or less, still more preferably 0 mass %, that is, it is preferable that the surfactant composition does not contain a solvent, from the viewpoint of sustainability, environmental load, safety, and the like. 
     The surfactant composition may be an emulsifier composition, a wetting agent composition, a penetrant composition, a composition for oil recovery, or a detergent composition. That is, the surfactant composition of the present invention may be an emulsifier composition, a wetting agent composition, a penetrant composition, a composition for oil recovery, or a detergent composition containing the surfactant and one or more kinds of the compound represented by the Chemical Formula (1). The composition for oil recovery is preferably a composition for crude oil recovery, more preferably a composition for EOR (Enhanced Oil Recovery, the same hereinafter), further preferably a composition for chemical EOR. 
     The surfactant composition of the present invention is used as, for example, a detergent such as a liquid detergent for clothing, a detergent for dishware, a detergent for hair, a detergent for body, a detergent for precision parts, and a detergent for hard surfaces. The surfactant composition of the present invention can be used for the respective cleaning applications when added to water and dissolved. 
     Composition for Oil Recovery 
     The composition for oil recovery of the present invention contains at least the co-surfactant. 
     The composition for oil recovery of the present invention preferably contains a surfactant. The surfactant is not particularly limited, and examples thereof include the above-mentioned surfactants. 
     The content of the surfactant in the composition for oil recovery is not particularly limited, but is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, further preferably 1 mass % or more, and preferably 80 mass % or less, more preferably 50 mass % or less, further preferably 30 mass % or less from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability with the co-surfactant. 
     The content of the co-surfactant in the composition for oil recovery is not particularly limited, but is preferably 10 mass % or more, more preferably 20 mass % or more, further preferably 30 mass % or more, and preferably 90 mass % or less, more preferably 70 mass % or less, further preferably 50 mass % or less with respect to the total content of the surfactant and the co-surfactant from the viewpoint of improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability. 
     The composition for oil recovery of the present invention may optionally contain a solvent, an inactivating agent (for example, an alkali metal salt), or a polymer (for example, xanthan rubber, polyacrylamide (PAM), and partially hydrolyzed polyacrylamide (HPAM)) as long as the effect of the present invention is not impaired. 
     The composition for oil recovery of the present invention is preferably a composition for crude oil recovery, more preferably a composition for EOR, further preferably a composition for chemical EOR. 
     The composition for oil recovery of the present invention can be used for the various oil-recovering applications when added to water and dissolved. 
     The present invention and preferred embodiments of the present invention are described below. 
     1 
     A co-surfactant comprising at least one kind of a compound represented by a Chemical Formula (1): 
     
       
         
         
             
             
         
       
     
     wherein R 1  is a hydrogen atom or an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, R 2  is an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, a total number of carbon atoms of R 1  and R 2  is 6 or more and 34 or less, X is a single bond or an aliphatic hydrocarbon group having 1 or more and 5 or less carbon atoms, and one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH or —O—CH(—CH 2 —OH) 2 . 
     2 
     A co-surfactant comprising at least one kind of a compound represented by a Chemical Formula (1): 
     
       
         
         
             
             
         
       
     
     wherein R 1  is a hydrogen atom or an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, R 2  is an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms, X is a single bond or an aliphatic hydrocarbon group having 1 or more and 5 or less carbon atoms, a total number of carbon atoms of R 1 , R 2  and X is 6 or more and 39 or less, and one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH or —O—CH(—CH 2 —OH) 2 . 
     3 
     The co-surfactant according to &lt;1&gt;or &lt;2&gt;, being composed of a compound represented by the Chemical Formula (1). 
     4 
     The co-surfactant according to &lt;1&gt;or &lt;2&gt;, being composed of one or more kinds of a compound represented by the Chemical Formula (1). 
     5 
     The co-surfactant according to any one of &lt;1&gt;to &lt;4&gt;, wherein R 1  is an aliphatic hydrocarbon group having 1 or more and 33 or less carbon atoms. 
     
       6 
     
     The co-surfactant according to any one of &lt;1&gt;to &lt;5&gt;, wherein each of the aliphatic hydrocarbon groups of R 1  and R 2  is preferably a linear alkyl group or a branched alkyl group, more preferably a linear alkyl group. 
     7 
     The co-surfactant according to any one of &lt;1&gt;to &lt;6&gt;, wherein a total number of substituents of R 1  and R 2  is preferably 5 or less, more preferably 3 or less, further preferably 1 or less, still more preferably 0 (that is, having no substituent). 
     8 
     The co-surfactant according to any one of &lt;1&gt;to &lt;7&gt;, wherein a total number of carbon atoms of R 1  and R 2  is preferably 8 or more, more preferably 10 or more, further preferably 12 or more, still more preferably 14 or more, and preferably 26 or less, more preferably 22 or less, further preferably 18 or less, still more preferably 16 or less. 
     9 
     The co-surfactant according to any one of &lt;1&gt;to &lt;8&gt;, wherein X is preferably a single bond or an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms, more preferably a single bond or an aliphatic hydrocarbon group having 1 or more and 2 or less carbon atoms, further preferably a single bond or an aliphatic hydrocarbon group having 1 carbon atom, still more preferably a single bond. 
     10 
     The co-surfactant according to any one of &lt;1&gt;to &lt;7&gt;, wherein 
     preferably a total number of carbon atoms of R 1  and R 2  is 8 or more and 26 or less, and X is a single bond or an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms, 
     more preferably a total number of carbon atoms of R 1  and R 2  is 10 or more and 22 or less, and X is a single bond or an aliphatic hydrocarbon group having 1 or more and 2 or less carbon atoms, 
     further preferably a total number of carbon atoms of R 1  and R 2  is 12 or more and 18 or less, and X is a single bond or an aliphatic hydrocarbon group having 1 carbon atom, 
     still more preferably a total number of carbon atoms of R 1  and R 2  is 14 or more and 16 or less, and X is a single bond. 
     11 
     The co-surfactant according to any one of &lt;1&gt;to &lt;10&gt;, wherein a total number of carbon atoms of R 1 , R 2  and X is preferably 8 or more, more preferably 10 or more, further preferably 12 or more, still more preferably 14 or more, and preferably 31 or less, more preferably 28 or less, further preferably 26 or less, still more preferably 25 or less, still more preferably 24 or less, still more preferably 22 or less, still more preferably 20 or less, still more preferably 18 or less, still more preferably 16 or less. 
     12 
     The co-surfactant according to any one of &lt;1&gt;to &lt;11&gt;, wherein when X is the aliphatic hydrocarbon group, X is preferably a linear alkyl group or branched alkyl group, more preferably a linear alkyl group. 
     13 
     The co-surfactant according to any one of &lt;1&gt;to &lt;11&gt;, wherein X is preferably 
     *—(CH 2 ) n —* (n is 0 or more and 5 or less, and * represents a binding site), 
     wherein n is preferably 0 or more, preferably 3 or less, more preferably 2 or less, further preferably 1 or less, still more preferably 0, that is, a single bond. 
     14 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, comprising two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     15 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, comprising two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms, and between which the total numbers of carbon atoms of R 1 , R 2  and X are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     16 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, comprising two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 2 or less carbon atoms, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     17 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, comprising two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 or more and 2 or less carbon atoms, and between which the total numbers of carbon atoms of R 1 , R 2  and X are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     18 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, comprising two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 carbon atom, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     19 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, comprising two or more kinds of the compound in which X is a single bond or an aliphatic hydrocarbon group having 1 carbon atom, and between which the total numbers of carbon atoms of R 1 , R 2  and X are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     20 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, comprising two or more kinds of the compound in which X is a single bond, and between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different. 
     21 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 12, a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is 75 mass % or more. 
     22 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 12, a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is 85 mass % or more. 
     23 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 12, a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 2  and R 2  is 16 is 95 mass % or more. 
     24 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 12, a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 2  and R 2  is 16 is 100 mass %. 
     25 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is 75 mass % or more. 
     26 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is 85 mass % or more. 
     27 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is 95 mass % or more. 
     28 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound in which X is a single bond and between which the total numbers of carbon atoms of R 1  and R 2  are different, the total content of two or more kinds of the compound selected from a compound in which the total number of carbon atoms of R 1  and R 2  is 14, and a compound in which the total number of carbon atoms of R 1  and R 2  is 16 is 99 mass % or more, preferably 100 mass %. 
     29 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound represented by the Chemical Formula (1) between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different, the content ratio of the compound in which the number of carbon atoms of R 1  is 5 or more and the number of carbon atoms of R 2  is 5 or more is 10 mass % or more and 90 mass % or less. 
     30 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound represented by the Chemical Formula (1) between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different, the content ratio of the compound in which the number of carbon atoms of R 1  is 5 or more and the number of carbon atoms of R 2  is 5 or more is 20 mass % or more and 80 mass % or less. 
     31 
     The co-surfactant according to any one of &lt;1&gt;to &lt;13&gt;, wherein when the co-surfactant contains two or more kinds of the compound represented by the Chemical Formula (1) between which the total numbers of carbon atoms of R 1  and R 2  are the same, but the numbers of carbon atoms of R 1  and the numbers of carbon atoms of R 2  are each different, the content ratio of the compound in which the number of carbon atoms of R 1  is 5 or more and the number of carbon atoms of R 2  is 5 or more is 30 mass % or more and 70 mass % or less. 
     32 
     The co-surfactant according to any one of &lt;1&gt;to &lt;31&gt;, comprising a compound 1 in which in the Chemical Formula (1), one of A 1  and A 2  is —OH and another is —O—CH 2 —CH(OH)—CH 2 OH, and a compound 2 in which in the Chemical Formula (1), one of A 1  and A 2  is —OH and another is —O—CH(—CH 2 —OH) 2 . 
     
       33 
     
     The co-surfactant according to &lt;32&gt;, wherein a content of the compound 1 is preferably 1 mass % or more, more preferably 30 mass % or more, further preferably 40 mass % or more, still more preferably 50 mass % or more, and preferably 99 mass % or less, more preferably 90 mass % or less, further preferably 80 mass % or less with respect to a total amount of the compound 1 and the compound 2. 
     
       34 
     
     The co-surfactant according to &lt;32&gt;, wherein a content of the compound 1 is preferably 1 to 99 mass %, more preferably 30 to 99 mass %, further preferably 40 to 90 mass %, still more preferably 50 to 80 mass %. 
     35 
     A surfactant composition comprising a surfactant and the co-surfactant according to any one of &lt;1&gt;to &lt;34&gt;. 
     
       36 
     
     The surfactant composition according to &lt;35&gt;, wherein the surfactant is an ionic surfactant or a nonionic surfactant. 
     37 
     The surfactant composition according to &lt;35&gt;or &lt;36&gt;, wherein a content of the surfactant in the surfactant composition is 0.01 mass % or more and 80 mass % or less. 
     38 
     The surfactant composition according to &lt;35&gt;or &lt;36&gt;, wherein a content of the surfactant in the surfactant composition is 0.1 mass % or more and 50 mass % or less. 
     39 
     The surfactant composition according to &lt;35&gt;or &lt;36&gt;, wherein a content of the surfactant in the surfactant composition is 1 mass % or more and 30 mass % or less. 
     40 
     The surfactant composition according to any one of &lt;35&gt;to &lt;39&gt;, wherein a content of the co-surfactant in the surfactant composition is 10 mass % or more and 90 mass % or less with respect to a total content of the surfactant and the co-surfactant. 
     41 
     The surfactant composition according to any one of &lt;35&gt;to &lt;39&gt;, wherein a content of the co-surfactant in the surfactant composition is 20 mass % or more and 70 mass % or less with respect to a total content of the surfactant and the co-surfactant. 
     42 
     The surfactant composition according to any one of &lt;35&gt;to &lt;39&gt;, wherein a content of the co-surfactant in the surfactant composition is 30 mass % or more and 50 mass % or less with respect to a total content of the surfactant and the co-surfactant. 
     43 
     The surfactant composition according to any one of &lt;35&gt;to &lt;42&gt;, comprising a solvent. 
     44 
     The surfactant composition according to &lt;43&gt;, wherein a content of the solvent in the surfactant composition is preferably 30 mass % or less, more preferably 20 mass % or less, further preferably 10 mass % or less, still more preferably 5 mass % or less, still more preferably 1 mass % or less. 
     45 
     The surfactant composition according to any one of &lt;35&gt;to &lt;44&gt;, wherein the surfactant composition is an emulsifier composition, a wetting agent composition, a penetrant composition, a composition for oil recovery, or a detergent composition. 
     46 
     The surfactant composition according to &lt;45&gt;, wherein the composition for oil recovery is preferably a composition for crude oil recovery, more preferably a composition for EOR (Enhanced Oil Recovery), further preferably a composition for chemical EOR. 
     47 
     The surfactant composition according to any one of &lt;35&gt;to &lt;44&gt;, being used as a detergent. 
     48 
     The surfactant composition according to any one of &lt;35&gt;to &lt;44&gt;, being used as a liquid detergent for clothing, a detergent for dishware, a detergent for hair, a detergent for body, a detergent for precision parts, or a detergent for hard surfaces. 
     49 
     A composition for oil recovery comprising the co-surfactant according to any one of &lt;1&gt;to &lt;34&gt;. 
     
       50 
     
     The composition for oil recovery according to &lt;49&gt;, further comprising a surfactant. 
     51 
     The composition for oil recovery according to &lt;50&gt;, wherein the surfactant is an ionic surfactant or a nonionic surfactant. 
     52 
     The composition for oil recovery according to &lt;50&gt;or &lt;51&gt;, wherein a content of the surfactant in the composition for oil recovery is 0.01 mass % or more and 80 mass % or less. 
     53 
     The composition for oil recovery according to &lt;50&gt;or &lt;51&gt;, wherein a content of the surfactant in the composition for oil recovery is 0.1 mass % or more and 50 mass % or less. 
     54 
     The composition for oil recovery according to &lt;50&gt;or &lt;51&gt;, wherein a content of the surfactant in the composition for oil recovery is 1 mass % or more and 30 mass % or less. 
     55 
     The composition for oil recovery according to any one of &lt;50&gt;to &lt;54&gt;, wherein a content of the co-surfactant in the composition for oil recovery is 10 mass % or more and 90 mass % or less with respect to a total content of the surfactant and the co-surfactant. 
     56 
     The composition for oil recovery according to any one of &lt;50&gt;to &lt;54&gt;, wherein a content of the co-surfactant in the composition for oil recovery is 20 mass % or more and 70 mass % or less with respect to a total content of the surfactant and the co-surfactant. 
     57 
     The composition for oil recovery according to any one of &lt;50&gt;to &lt;54&gt;, wherein a content of the co-surfactant in the composition for oil recovery is 30 mass % or more and 50 mass % or less with respect to a total content of the surfactant and the co-surfactant. 
     58 
     The composition for oil recovery according to any one of &lt;49&gt;to &lt;57&gt;, wherein the composition for oil recovery is preferably a composition for crude oil recovery, more preferably a composition for EOR (Enhanced Oil Recovery), further preferably a composition for chemical EOR. 
     59 
     Use of the surfactant composition according to any one of &lt;35&gt;to &lt;44&gt;as a composition for oil recovery. 
     60 
     Use of the surfactant composition according to any one of &lt;35&gt;to &lt;44&gt;as a composition for EOR. 
     EXAMPLES 
     Hereinafter, a specific description is made of the present invention with reference to Examples. The content of each component is expressed in mass % unless otherwise indicated in Tables. Various measuring methods are as follows. 
     Method for Measuring Double Bond Distribution in Olefin 
     The double bond distribution in olefin was measured by gas chromatography (hereinafter, abbreviated as GC). Specifically, dimethyl disulfide was reacted with olefin to form a dithioated derivative, and then respective components were separated by GC. The double bond distribution in olefin was determined from respective peak areas. The apparatus used for measurement and analyzing conditions are as follows. 
     GC apparatus: Trade name HP6890 (manufactured by Hewlett-Packard Company) 
     Column: Trade name Ultra-Alloy-1 HT capillary column 30 m×250 μm×0.15 μm (manufactured by Frontier Laboratories, Ltd.) 
     Detector: Hydrogen flame ion detector (FID) 
     Injection temperature: 300° C. 
     Detector temperature: 350° C. 
     Oven: 60° C. (0 min.)→2° C./min.→225° C.→20° C./min.→350° C.—350° C. (5.2 min.) 
     Method for Measuring Content Ratio of Structural Isomer 
     Measurement was performed by  1 H-NMR for a mixture of 0.05 g of alkyl glyceryl ether, 0.2 g of trifluoroacetic anhydride, and 1 g of deuterated chloroform. Measuring conditions are as follows. 
     Nuclear magnetic resonance apparatus: Agilent 400-MR DD2, manufactured by Agilent Technologies, Inc. 
     Observation range: 6410.3 Hz 
     Data point: 65536 
     Measurement mode: Presat 
     Pulse width: 45° 
     Pulse delay time: 10 sec 
     Cumulative number: 128 times 
     Production of Internal Olefin 
     Production Example A1 
     (Production of Internal Olefin having 16 Carbon Atoms (Internal Olefin 1)) 
     A flask equipped with a stirrer was charged with 7000 g (28.9 mol) of 1-hexadecanol (Product name: KALCOL 6098, manufactured by Kao Corporation) and 700 g (10 wt % with respect to the raw material alcohol) of y-alumina (STREM Chemicals, Inc.) as a solid acid catalyst, followed by reaction at 280° C. for 32 hours under stirring with circulation of nitrogen (7000 mL/min) in the system. The alcohol conversion after completion of the reaction was 100%, and the purity of C16 olefin was 99.6%. The obtained crude C16 internal olefin was transferred to a distiller, followed by distillation at 136 to 160° C./4.0 mmHg to yield an internal olefin 1 having an olefin purity of 100%. The double bond distribution in the obtained internal olefin 1 was 0.2% at the Cl position, 15.8% at the C2 position, 14.5% at the C3 position, 15.7% at the C4 position, 17.3% at the C5 position, 16.5% at the C6 position, and 20.0% at the C7 position and the C8 position in total. 
     Production Example A2 
     (Production of Internal Olefin having 18 Carbon Atoms (Internal Olefin 2)) 
     A reactor equipped with a stirrer was charged with 800 kg (3.0 kmol) of 1-octadecanol (Product name: KALCOL 8098, manufactured by Kao Corporation) and 80 kg (10 wt % with respect to the raw material alcohol) of activated alumina GP-20 (Mizusawa Industrial Chemicals, Ltd.) as a solid acid catalyst, followed by reaction at 280° C. for 16 hours under stirring with circulation of nitrogen (15 L/min) in the system. The alcohol conversion after completion of the reaction was 100%, and the purity of C18 olefin was 98.7%. The obtained crude C18 internal olefin was transferred to a distiller, followed by distillation at 163 to 190° C./4.6 mmHg to yield an internal olefin 2 having an olefin purity of 100%. The double bond distribution in the obtained internal olefin 2 was 0.3% at the C1 position, 13.3% at the C2 position, 12.6% at the C3 position, 13.9% at the C4 position, 14.8% at the C5 position, 13.7% at the C6 position, 12.6% at the C7 position, and 18.8% at the C8 position and the C9 position in total. 
     Production Example A3 
     (Production of Internal Olefin having 14 Carbon Atoms (Internal Olefin 3)) 
     An internal olefin 3 was obtained in the same manner as in Production Example A1 except that 28.9 mol of 1-tetradecanol (Product name: KALCOL 4098, manufactured by Kao Corporation) was used in place of 28.9 mol of 1-hexadecanol (Product name: KALCOL 6098, manufactured by Kao Corporation) for Production Example A1. The double bond distribution in the obtained internal olefin 3 was 1.3% at the C1 position, 31.8% at the C2 position, 23.8% at the C3 position, 21.0% at the C4 position, 8.5% at the C5 position, and 13.6% at the C6 position and C7 position in total. 
     Production of Internal Epoxide 
     Production Example B1 
     (Production of Internal Epoxide having 16 carbon Atoms (Internal Epoxide 1)) 
     A flask equipped with a stirrer was charged with the internal olefin 1 (800 g, 3.56 mol) obtained in Production Example A1, 107 g (1.78 mol) of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 15.6 g (0.15 mol) of sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), 415.7 g (4.28 mol) of 35% hydrogen peroxide (manufactured by Wako Pure Chemical Industries, Ltd.), and 25.3 g (0.18 mol) of sodium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.), followed by reaction at 50° C. for 4 hours. Thereafter, the temperature was raised to 70° C. to allow the mixture to react further for 2 hours. After the reaction, the layers were separated to remove an aqueous layer, and an oil layer was washed with ion-exchanged water, a saturated aqueous sodium carbonate solution (manufactured by Wako Pure Chemical Industries, Ltd.), a saturated aqueous sodium sulfite solution (manufactured by Wako Pure Chemical Industries, Ltd.), and 1% saline (manufactured by Wako Pure Chemical Industries, Ltd.), followed by concentration in an evaporator to yield 820 g of an internal epoxide 1. 
     Production Example B2 
     (Production of Internal Epoxide having 18 Carbon Atoms (Internal Epoxide 2)) 
     A flask equipped with a stirrer was charged with the internal olefin 2 (595 g, 2.38 mol) obtained in Production Example A2, 71.7 g (1.20 mol) of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 9.8 g (0.10 mol) of sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), and 324 g (4.00 mol) of 35% hydrogen peroxide (manufactured by Wako Pure Chemical Industries, Ltd.), followed by reaction at 50° C. for 4 hours. Thereafter, the temperature was raised to 80° C. to allow the mixture to react further for 5 hours. After the reaction, the layers were separated to remove an aqueous layer, and an oil layer was washed with ion-exchanged water, a saturated aqueous sodium carbonate solution (manufactured by Wako Pure Chemical Industries, Ltd.), a saturated aqueous sodium sulfite solution (manufactured by Wako Pure Chemical Industries, Ltd.), and ion-exchanged water, followed by concentration in an evaporator to yield 629 g of an internal epoxide 2. 
     Production Example B3 
     (Production of Internal Epoxide having 14 Carbon Atoms (Internal Epoxide 3)) 
     An internal epoxide 3 was obtained in the same manner as in Production Example B1 except that the internal olefin 3 (3.56 mol) obtained in Production Example A3 was used in place of the internal olefin 1 (3.56 mol) obtained in Production Example A1. 
     Production of Reactant of Epoxide and Glycerin (Alkyl Glyceryl Ether, AGE) 
     Hereinafter, the alkyl glyceryl ether is referred to as AGE. In addition, AGE1, AGE2, AGES, and the like represent alkyl glyceryl ether 1, alkyl glyceryl ether 2, alkyl glyceryl ether 3, and the like, respectively. 
     Production Example C1 
     (Production of Reactant of Internal Epoxide 1 and Glycerin (AGE1)) 
     A flask equipped with a stirrer was charged with 2298 g (25.0 mol) of glycerin (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.122 g (1.25 mmol) of 98% sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), and the temperature was raised to 130° C. Thereafter, the internal epoxide 1 (300 g, 1.25 mol) obtained in Production Example B1 was added dropwise over 1 hour, followed by reaction at 130° C./8 hours. Hexane was added to the liquid obtained by this reaction, followed by washing with ion-exchanged water. Subsequently, concentration was performed under reduced pressure in an evaporator to yield 400 g of AGE1. The obtained AGE1 wherein in the Chemical Formula (1), R 1  and R 2  each contain an alkyl group having 1 to 13 carbon atoms, the total number of carbon atoms of R 1  and R 2  is 14, X is a single bond, one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH or —O—CH(—CH 2 —OH) 2 , contained 73% ether alcohol 1 (AGE obtained by reacting the hydroxyl group at the 1-position of glycerin with the epoxy group) in which A 1  or A 2  was —O—CH 2 —CH(OH)—CH 2 OH, and 27% ether alcohol 2 (AGE obtained by reacting the hydroxyl group at the 2-position of glycerin with the epoxy group) in which A 1  or A 2  was —O—CH(—CH 2 —OH) 2 . 
     Production Example C2 
     (Production of Reactant of Internal Epoxide 2 and Glycerin (AGE2)) 
     An AGE2 was obtained in the same manner as in Production Example C1 except that the internal epoxide 2 (1.25 mol) obtained in Production Example B2 was used in place of the internal epoxide 1 (1.25 mol) obtained in Production Example B1. The obtained AGE2 wherein in the Chemical Formula (1), R 1  and R 2  each contain an alkyl group having 1 to 15 carbon atoms, the total number of carbon atoms of R 1  and R 2  is 16, X is a single bond, one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH or —O—CH(—CH 2 —OH) 2 , contained 72% AGE obtained by reacting the hydroxyl group at the 1-position of glycerin with the epoxy group, and 28% AGE obtained by reacting the hydroxyl group at the 2-position of glycerin with the epoxy group. 
     Production Example C3 
     (Production of Reactant of Internal Epoxide 3 and Glycerin (AGE3)) 
     An AGE3 was obtained in the same manner as in Production Example C1 except that the internal epoxide 3 (1.25 mol) obtained in Production Example B3 was used in place of the internal epoxide 1 (1.25 mol) obtained in Production Example B1. The obtained AGES wherein in the Chemical Formula (1), R 1  and R 2  each contain an alkyl group having 1 to 11 carbon atoms, the total number of carbon atoms of R 1  and R 2  is 12, X is a single bond, one of A 1  and A 2  is —OH and the other is —O—CH 2 —CH(OH)—CH 2 OH or —O—CH(—CH 2 —OH) 2 , contained 74% AGE obtained by reacting the hydroxyl group at the 1-position of glycerin with the epoxy group, and 26% AGE obtained by reacting the hydroxyl group at the 2-position of glycerin with the epoxy group. 
     The chemicals used in Examples 1 and 2 are as follows. 
     Surfactant 1: sodium lauryl sulfate (EMAL 10 G, manufactured by Kao Corporation) 
     Surfactant 2: polyoxyethylene alkyl ether sulfate (LATEMUL E-118B, manufactured by Kao Corporation) 
     Surfactant 3: potassium oleate soap (OS Soap, manufactured by Kao Corporation) 
     Surfactant 4: decyl glucoside (MYDOL 10, manufactured by Kao Corporation) 
     Surfactant 5: lauryl glucoside (MYDOL 12, manufactured by Kao Corporation) 
     Surfactant 6: lauryltrimethylammonium chloride (QUARTAMIN 24P, manufactured by Kao Corporation) 
     Co-surfactant 1: AGE2 obtained in Production Example C2 
     Co-surfactant 2: AGE1 obtained in Production Example C1 
     Co-surfactant 3: AGE3 obtained in Production Example C3 
     Co-surfactant 4: isostearyl glyceryl ether (PENETOL GE-IS, manufactured by Kao Corporation) 
     Comparative Product 1: polyoxyethylene (3) lauryl ether (EMULGEN 103, manufactured by Kao Corporation) 
     Comparative Product 2: polyoxyethylene (9) lauryl ether (EMULGEN 109P, manufactured by Kao Corporation) 
     Comparative Product 3: 2-ethylhexylglyceryl ether (2-ethylhexyl glyceryl ether can be produced, for example, by the method described in paragraphs [0002] and [0003] of JP-A-2008-156289.) 
     Evaluation of Auxiliary Effect 
     Example 1 (Examples 1-1 to 1-14, Comparative Examples 1-1 to 1-18) 
     In a 50 mL screw tube, 40 mL of an oil agent described in Table 1 or Table 2 and ion-exchanged water were put at a volume ratio of 1:1, and each surfactant and each co-surfactant described in Table 1 or Table 2 were added at a ratio described in Table 1 or Table 2 with respect to 40 mL. Immediately after shaking for 30 seconds, one droplet was placed on a slide glass, covered with a cover glass, and observed at a magnification of 500 times using a digital microscope VHX-6000 (manufactured by KEYENCE CORPORATION). The particle diameters of micelles in the droplet were measured to determine an average particle diameter (μm) as the arithmetic average of the particle diameters of 100 micelles. The auxiliary effect was calculated by the following formula. The average particle diameter is preferably as small as possible, and the auxiliary effect is higher as the value is larger. 
       Auxiliary effect =[Average particle diameter (in the absence of co-surfactant)/Average particle diameter (in the presence of co-surfactant)]/(Total mass of co-surfactant/Total mass of surfactant and co-surfactant) 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                   
                   
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                   
                 1-1 
                 1-2 
                 1-3 
                 1-4 
                 1-5 
                 1-6 
                 1-7 
               
               
                   
               
               
                 Surfactant 
                 Surfactant 1 
                 4 
                 3 
                 2.5 
                 4 
                 3 
                 3 
                 4 
               
               
                 [vol %] 
                 Surfactant 2 
               
               
                   
                 Surfactant 3 
               
               
                   
                 Surfactant 4 
               
               
                   
                 Surfactant 6 
               
               
                 Co-surfactant 
                 Co-surfactant 1 
                 1 
                 2 
                 2.5 
               
               
                 [vol %] 
                 Co-surfactant 2 
                   
                   
                   
                 1 
                 2 
               
               
                   
                 Co-surfactant 3 
                   
                   
                   
                   
                   
                 2 
               
               
                   
                 Co-surfactant 4 
                   
                   
                   
                   
                   
                   
                 1 
               
               
                   
                 Comparative 
               
               
                   
                 Product 1 
               
               
                   
                 Comparative 
               
               
                   
                 Product 2 
               
               
                   
                 Comparative 
               
               
                   
                 Product 3 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Oil agent 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
               
               
                 Average particle diameter 
                 13 
                 2 
                 1 
                 13 
                 2 
                 3 
                 10 
               
               
                 [μm] 
               
               
                 Auxiliary effect 
                 21 
                 68  
                 108 
                 21 
                 68  
                 45  
                 27 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                   
                 1-8 
                 1-9 
                 1-10 
                 1-11 
                 1-12 
                 1-13 
                 1-14 
               
               
                   
               
               
                 Surfactant 
                 Surfactant 1 
                 3 
                   
                   
                   
                   
                 3 
               
               
                 [vol %] 
                 Surfactant 2 
                   
                 3 
               
               
                   
                 Surfactant 3 
                   
                   
                 3 
               
               
                   
                 Surfactant 4 
                   
                   
                   
                 3 
                   
                   
                 4 
               
               
                   
                 Surfactant 6 
                   
                   
                   
                   
                 3 
               
               
                 Co-surfactant 
                 Co-surfactant 1 
                   
                 2 
                 2 
                 2 
                 2 
                 2 
                 1 
               
               
                 [vol %] 
                 Co-surfactant 2 
               
               
                   
                 Co-surfactant 3 
               
               
                   
                 Co-surfactant 4 
                 2 
               
               
                   
                 Comparative 
               
               
                   
                 Product 1 
               
               
                   
                 Comparative 
               
               
                   
                 Product 2 
               
               
                   
                 Comparative 
               
               
                   
                 Product 3 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Oil agent 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 C12 α- 
                 Octane 
               
               
                   
                   
                   
                   
                   
                   
                 olefin 
               
               
                 Average particle diameter 
                 6 
                 1 
                 1 
                 1 
                 1 
                 10 
                 12 
               
               
                 [μm] 
               
               
                 Auxiliary effect 
                 23  
                 100  
                 70  
                 35  
                 60  
                 22 
                 21 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                   
                   
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
               
               
                   
                   
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
               
               
                   
                   
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                   
                 1-1 
                 1-2 
                 1-3 
                 1-4 
                 1-5 
                 1-6 
                 1-7 
                 1-8 
                 1-9 
               
               
                   
               
               
                 Surfactant 
                 Surfactant 1 
                 5 
                   
                   
                   
                   
                   
                   
                   
                 4 
               
               
                 [vol %] 
                 Surfactant 2 
                   
                 5 
               
               
                   
                 Surfactant 3 
                   
                   
                 5 
               
               
                   
                 Surfactant 4 
                   
                   
                   
                 5 
               
               
                   
                 Surfactant 6 
                   
                   
                   
                   
                 5 
               
               
                 Co-surfactant 
                 Co-surfactant 1 
               
               
                 [vol %] 
                 Co-surfactant 2 
               
               
                   
                 Co-surfactant 3 
               
               
                   
                 Co-surfactant 4 
               
               
                   
                 Comparative 
                   
                   
                   
                   
                   
                 5 
                   
                   
                 1 
               
               
                   
                 Product 1 
               
               
                   
                 Comparative 
                   
                   
                   
                   
                   
                   
                 5 
               
               
                   
                 Product 2 
               
               
                   
                 Comparative 
                   
                   
                   
                   
                   
                   
                   
                 5 
               
               
                   
                 Product 3 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 Oil agent 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
               
               
                 Average particle diameter 
                 54  
                 40  
                 28  
                 14  
                 24  
                 101  
                 5 
                 Separated 
                 117  
               
               
                 [μm] 
               
               
                 Auxiliary effect 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 2 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
                 Compara- 
               
               
                   
                   
                   
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
                 tive 
               
               
                   
                   
                   
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                   
                   
                 1-10 
                 1-11 
                 1-12 
                 1-13 
                 1-14 
                 1-15 
                 1-16 
                 1-17 
                 1-18 
               
               
                   
                   
               
               
                   
                 Surfactant 
                 Surfactant 1 
                 3 
                 2.5 
                 4 
                 3 
                 2.5 
                 4 
                 3 
                 5 
               
               
                   
                 [vol %] 
                 Surfactant 2 
               
               
                   
                   
                 Surfactant 3 
               
               
                   
                   
                 Surfactant 4 
                   
                   
                   
                   
                   
                   
                   
                   
                 5 
               
               
                   
                   
                 Surfactant 6 
               
               
                   
                 Co-surfactant 
                 Co-surfactant 1 
               
               
                   
                 [vol %] 
                 Co-surfactant 2 
               
               
                   
                   
                 Co-surfactant 3 
               
               
                   
                   
                 Co-surfactant 4 
               
               
                   
                   
                 Comparative 
                 2 
                 2.5 
               
               
                   
                   
                 Product 1 
               
               
                   
                   
                 Comparative 
                   
                   
                 1 
                 2 
                 2.5 
               
               
                   
                   
                 Product 2 
               
               
                   
                   
                 Comparative 
                   
                   
                   
                   
                   
                 1 
                 2 
               
               
                   
                   
                 Product 3 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Oil agent 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
                 C12 α- 
                 Octane 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 olefin 
               
               
                   
                 Average particle diameter 
                 134  
                 134 
                 41  
                 28  
                 21 
                 30  
                 11 
                 87  
                 50  
               
               
                   
                 [μm] 
               
               
                   
                 Auxiliary effect 
                 1 
                 1 
                 7 
                 5 
                 5 
                 9 
                 12 
                 — 
                 — 
               
               
                   
                   
               
            
           
         
       
     
     Evaluation of Microemulsion Forming Ability 
     Example 2 (Examples 2-1 to 2-12, Comparative Examples 2-1 to 2-8) 
     A salt aqueous solution was prepared so as to have each salt concentration described in Table 3 or Table 4 by adjustment with ion-exchanged water at a mass ratio of NaCl: CaCl 2 =20:6. In a 50 mL screw tube, 40 mL of each oil agent and the prepared salt aqueous solution were put at a volume ratio of 1:1, and each surfactant and each co-surfactant described in Table 3 or Table 4 were added in a ratio described in Table 3 or Table 4 with respect to 40 mL. Then, the tube was sealed and shaken for 30 seconds. After standing at 80° C. for 3 days, the appearance was observed. In the case of separation into three layers, “there is considered to be microemulsion formation”, and in other cases, “there is considered to be no microemulsion formation”. The results are shown in Table 3 or Table 4. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
             
            
               
                   
                   
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                   
                 2-1 
                 2-2 
                 2-3 
                 2-4 
                 2-5 
                 2-6 
               
               
                   
               
               
                 Co-surfactant 
                 Co-surfactant 1 
                 0.25 
                 0.25 
               
               
                 [vol %] 
                 Co-surfactant 2 
                   
                   
                 0.25 
                 0.25 
               
               
                   
                 Co-surfactant 3 
                   
                   
                   
                   
                 0.25 
               
               
                   
                 Co-surfactant 4 
                   
                   
                   
                   
                   
                 0.25 
               
               
                 Surfactant 
                 Surfactant 5 
                 0.75 
                 0.75 
                 0.75 
                 0.75 
                 0.75 
                 0.75 
               
               
                 [vol %] 
                 Surfactant 4 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Salt concentration [mass %] 
                 3 
                 26 
                 3 
                 26 
                 26 
                 3 
               
               
                 Oil agent 
                 Octane 
                 Octane 
                 Octane 
                 Octane 
                 Octane 
                 Octane 
               
               
                 Formation of microemulsion 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                   
                 2-7 
                 2-8 
                 2-9 
                 2-10 
                 2-11 
                 2-12 
               
               
                   
               
               
                 Co-surfactant 
                 Co-surfactant 1 
                   
                   
                 0.25 
                 0.25 
                 0.25 
                 0.25 
               
               
                 [vol %] 
                 Co-surfactant 2 
               
               
                   
                 Co-surfactant 3 
               
               
                   
                 Co-surfactant 4 
                 0.25 
                 0.5 
               
               
                 Surfactant 
                 Surfactant 5 
                 0.75 
                 0.5 
                   
                   
                 0.75 
                 0.75 
               
               
                 [vol %] 
                 Surfactant 4 
                   
                   
                 0.75 
                 0.75 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Salt concentration [mass %] 
                 26 
                 3 
                 3 
                 26 
                 3 
                 26 
               
               
                 Oil agent 
                 Octane 
                 Octane 
                 Octane 
                 Octane 
                 Toluene 
                 Toluene 
               
               
                 Formation of microemulsion 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
               
               
                   
                 Example 2-1 
                 Example 2-2 
                 Example 2-3 
                 Example 2-4 
                 Example 2-5 
                 Example 2-6 
                 Example 2-7 
                 Example 2-8 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Co-surfactant 
                 Co-surfactant 1 
                   
                   
                   
                   
                   
                   
               
               
                 [vol %] 
                 Co-surfactant 2 
               
               
                   
                 Co-surfactant 3 
               
               
                   
                 Co-surfactant 4 
               
               
                 Surfactant 
                 Surfactant 5 
                 1 
                 1 
                   
                   
                 1 
                 1 
               
               
                 [vol %] 
                 Surfactant 4 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Salt concentration [mass %] 
                 3 
                 26 
                 3 
                 26 
                 3 
                 26 
                 3 
                 26 
               
               
                 Oil agent 
                 Octane 
                 Octane 
                 Octane 
                 Octane 
                 Toluene 
                 Toluene 
                 Toluene 
                 Toluene 
               
               
                 Formation of microemulsion 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
               
            
           
         
       
     
     INDUSTRIAL APPLICABILITY 
     The co-surfactant of the present invention is useful as an auxiliary agent for improving the functions of the surfactant such as reduction in particle diameter of surfactant micelles and development of microemulsion forming ability.