Low-temperature fluidity improver for fatty acid alkyl ester fuels, fatty acid alkyl ester fuel composition, and diesel fuel composition

Abstract

This low-temperature fluidity improver for fatty acid alkyl ester fuels comprises a copolymer (A) containing, as essential constituent monomers, a (meth)acrylic acid alkyl ester monomer (a) having an alkyl group having 1 to 5 carbon atoms, a monomer (c) represented by general formula (1), and a (meth)acrylic acid alkyl ester monomer (b) that is other than the monomer (c) and has an alkyl group having 6 to 32 carbon atoms. The weight ratio (a / c) of the monomer (a) to the monomer (c) among the monomers constituting the copolymer (A) is 0.015 to 12.5. [In general formula (1), R1 represents a hydrogen atom or a methyl group, and R2 and R3 each independently represent a linear or branched alkyl group having 8 to 24 carbon atoms.]

Description

Cold flow improver for fatty acid alkyl ester fuel, fatty acid alkyl ester fuel composition, and diesel fuel composition

[0001] The present invention relates to a cold flow improver for fatty acid alkyl ester fuels, a fatty acid alkyl ester fuel composition, and a diesel fuel composition.

[0002] Fatty acid alkyl esters, such as fatty acid methyl esters, obtained by transesterification of fats and oils, particularly fats and oils derived from vegetable oils, with lower aliphatic alcohols (e.g., methanol, etc.), have physical properties such as viscosity and specific gravity, and combustion properties similar to those of diesel oil, and their potential as diesel fuels that can be used without engine modification has long been recognized. Recently, fatty acid alkyl esters derived from vegetable oils have begun to be widely used in the United States and Europe as recyclable biofuels (e.g., biodiesel fuels) in the United States and Europe. However, in Europe and the United States, those derived from new vegetable oils are mainly used, and due to their higher cost compared to diesel, which is a common diesel fuel, they are mainly used in blends with diesel oil. Furthermore, quality standards have been established in Japan, Europe, and the United States to ensure the safe use of biodiesel fuels composed of fatty acid alkyl esters as automotive fuels, and they must meet the quality requirements specified in JIS K 2390:2016 in Japan and EN 14214 in Europe.

[0003] Meanwhile, cooking oil (waste cooking oil) used and discarded in restaurants, food factories, ordinary households, etc. has generally been treated with a coagulant and then buried in the ground, or simply disposed of as household waste and incinerated, etc. However, in recent years, with the growing interest in purifying the global environment, efforts to effectively reuse such waste cooking oil have begun to gain momentum, and one such effort is the production of oil suitable for biodiesel fuel by obtaining fatty acid alkyl esters through a transesterification reaction with lower aliphatic alcohols.

[0004] In order to satisfy the above-mentioned quality standards, high-purity fatty acid alkyl esters with extremely low impurities can be obtained by a purification process, such as washing the fatty acid alkyl esters after reaction. In particular, by using vacuum distillation as the purification process, it is possible to obtain fatty acid alkyl esters with a higher content of saturated fatty acid alkyl esters than when washed with water. The higher the purity of the fatty acid alkyl ester, the more its inherent physical properties become apparent and it tends to solidify at low temperatures. Therefore, biodiesel fuels containing high-purity fatty acid alkyl esters have high pour points and cold filter plugging points (CFPP). When fatty acid alkyl esters are blended at high concentrations or when used in cold regions even at low concentrations, the fluidity of the fuel deteriorates, which can cause clogging of filters and pumps. Therefore, in order to popularize biodiesel fuels, it is necessary to improve their low-temperature fluidity.

[0005] Meanwhile, various cold flow improvers are known for existing biodiesel fuels. For example, Patent Document 1 describes the use of an alkyl methacrylate polymer having a specific carbon chain length and molecular weight distribution. Patent Document 2 also describes the use of a copolymer obtained by polymerizing specific monomers in a specific ratio. However, regardless of the polymer used, there is a problem that the cold flow improvement effect (particularly the effect of reducing CFPP) is insufficient. Furthermore, from the perspective of ease of addition to fuel, cold flow improvers are generally distributed on the market as a solution containing a high concentration of polymer in diluent oil. However, such a solution containing a high concentration of polymer is prone to solidification at low temperatures, making it difficult to handle.

[0006] JP 2005-350629 A JP 2011-157555 A

[0007] An object of the present invention is to provide a low-temperature flow improver for fatty acid alkyl ester fuels that has a high low-temperature flow improving effect and is resistant to solidification at low temperatures. Another object of the present invention is to provide a fatty acid alkyl ester fuel composition and a diesel fuel composition that have excellent low-temperature flow properties.

[0008] As a result of extensive research, the present inventors have arrived at the present invention. Specifically, the present invention relates to a cold flow improver for fatty acid alkyl ester fuels, which comprises a copolymer (A) containing, as essential constituent monomers, a (meth)acrylic acid alkyl ester monomer (a) having an alkyl group containing 1 to 5 carbon atoms, a monomer (c) represented by the following general formula (1), and a (meth)acrylic acid alkyl ester monomer (b) other than the monomer (c) having an alkyl group containing 6 to 32 carbon atoms, wherein the weight ratio (a / c) of the monomers (a) to (c) among the monomers constituting the copolymer (A) is 0.015 to 12.5; a fatty acid alkyl ester fuel composition containing the cold flow improver for fatty acid alkyl ester fuels and the fatty acid alkyl ester (C); and a diesel fuel composition containing the fatty acid alkyl ester fuel composition and diesel.

[0009] [In general formula (1), R １ represents a hydrogen atom or a methyl group, R ２ and R ３ each independently represents a linear or branched alkyl group having 8 to 24 carbon atoms.

[0010] The present invention provides a low-temperature flow improver for fatty acid alkyl ester fuels that has a high low-temperature flow improving effect and is resistant to solidification at low temperatures.The present invention also provides a fatty acid alkyl ester fuel composition and a diesel fuel composition that have excellent low-temperature flow properties.

[0011] The cold flow improver for fatty acid alkyl ester fuels of the present invention comprises a copolymer (A) containing, as essential constituent monomers, a (meth)acrylic acid alkyl ester monomer (a) having an alkyl group containing 1 to 5 carbon atoms, a monomer (c) represented by the following general formula (1), and a (meth)acrylic acid alkyl ester monomer (b) other than the monomer (c) having an alkyl group containing 6 to 32 carbon atoms, wherein the weight ratio (a / c) of the monomer (a) to the monomer (c) among the monomers constituting the copolymer (A) is 0.015 to 12.5:

[0012] [In general formula (1), R１ represents a hydrogen atom or a methyl group, R ２ and R ３ each independently represents a linear or branched alkyl group having 8 to 24 carbon atoms.

[0013] <Copolymer (A)> Copolymer (A) contains, as essential constituent monomers, a (meth)acrylic acid alkyl ester monomer (a) having an alkyl group with a carbon number of 1 to 5, a monomer (c) represented by the following general formula (1), and a (meth)acrylic acid alkyl ester monomer (b) other than the monomer (c) having an alkyl group with a carbon number of 6 to 32. The weight ratio (a / c) of the monomer (a) to the monomer (c) among the monomers constituting copolymer (A) is 0.015 to 12.5:

[0014] [In general formula (1), R １ represents a hydrogen atom or a methyl group, R ２ and R ３ each independently represents a linear or branched alkyl group having 8 to 24 carbon atoms.] In the present invention, "(meth)acrylic" means "acrylic and / or methacrylic." Each of the monomers (a), (b), and (c) may be used alone or in combination of two or more.

[0015] In the present invention, the copolymer (A) contains, as a constituent monomer, a (meth)acrylic acid alkyl ester monomer (a) having an alkyl group containing 1 to 5 carbon atoms. A homopolymer of the monomer (a) has a low crystallization onset temperature. It is presumed that the inclusion of the monomer (a) as a constituent monomer in the copolymer (A) can inhibit the copolymer (A) from crystallizing in the fatty acid alkyl ester (C), thereby enabling the crystals of the fatty acid alkyl ester (C) to be dispersed into small particles even at lower temperatures, thereby further reducing the CFPP. Examples of the (meth)acrylic acid alkyl ester monomer (a) having an alkyl group containing 1 to 5 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, and neopentyl (meth)acrylate. As the monomer (a), from the viewpoint of low-temperature fluidity, alkyl methacrylates are preferred, and more preferred are methyl methacrylate, ethyl methacrylate, n-propyl methacrylate and n-butyl methacrylate.

[0016] The monomer (c) represented by the general formula (1) is a (meth)acrylic acid alkyl ester monomer having a branched alkyl group at the 2-position. It is presumed that the copolymer (A) containing the monomer (c) as a constituent monomer makes the copolymer (A) less likely to crystallize, and that even when a solution containing the copolymer (A) at a high concentration in a diluent oil is prepared, the solution is less likely to solidify. In the general formula (1), R １ represents a hydrogen atom or a methyl group, and from the viewpoint of low temperature fluidity (CFPP), a methyl group is preferred. ２ and R ３each independently represents a linear or branched alkyl group having 8 to 24 carbon atoms, and examples thereof include linear alkyl groups (e.g., n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, and n-tetracosyl group), branched alkyl groups [e.g., isooctyl group, 2-ethylhexyl group, isononyl group, 3,5,5-trimethylhexyl group, and the like], xyl group, 2,4,6-trimethylheptyl group, 2-methylnonyl group, isodecyl group, 2-ethylnonyl group, isoundecyl group, isododecyl group, 2-ethyldodecyl group, 2-ethyltridecyl group, 2-methyltetradecyl group, isohexadecyl group, 2-octylnonyl group, 2-hexylundecyl group, 2-ethylpentadecyl group, 2-(3-methylhexyl)-7-methyl-nonyl group, isooctadecyl group, 1-hexyltridecyl group, 2-ethylheptadecyl group, isoicosyl group, 1-octylpentadecyl group, and 2-decyltetradecyl group. ２ and R ３ The total number of carbon atoms is preferably 16 to 34, and more preferably 20 to 30, from the viewpoint of making the cold flow improver less likely to solidify at low temperatures.

[0017] Examples of the monomer (c) include 2-octyldecyl (meth)acrylate, 2-octyldodecyl (meth)acrylate, 2-octyltetradecyl (meth)acrylate, 2-octylhexadecyl (meth)acrylate, 2-octyloctadecyl (meth)acrylate, 2-octylicosyl (meth)acrylate, 2-octyldocosyl (meth)acrylate, 2-octyltetracosyl (meth)acrylate, 2-decyltetradecyl (meth)acrylate, 2-decylhexadecyl (meth)acrylate, 2-decyloctadecyl (meth)acrylate, 2-decylicosyl (meth)acrylate, 2-decyldocosyl (meth)acrylate, and (meth)acrylate. Examples of the acrylate include 2-decyltetracosyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, 2-dodecyloctadecyl (meth)acrylate, 2-dodecylicosyl (meth)acrylate, 2-dodecyldocosyl (meth)acrylate, 2-dodecyltetracosyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, 2-tetradecylicosyl (meth)acrylate, 2-tetradecyldocosyl (meth)acrylate, 2-tetradecyltetracosyl (meth)acrylate, 2-hexadecylicosyl (meth)acrylate, 2-hexadecyldocosyl (meth)acrylate, and 2-hexadecyltetracosyl (meth)acrylate. As the monomer (c), from the viewpoint of making the low-temperature fluidity improver less likely to solidify at low temperatures, alkyl methacrylates are preferred, and 2-octyldodecyl methacrylate, 2-decyltetradecyl methacrylate, 2-dodecylhexadecyl methacrylate, and 2-tetradecyloctadecyl methacrylate are more preferred.

[0018] In the present invention, the copolymer (A) contains, as a constituent monomer, a (meth)acrylic acid alkyl ester monomer (b) other than the monomer (c), in which the alkyl group has a carbon number of 6 to 32. It is presumed that the copolymer (A) having the monomer (b) as a constituent monomer enhances the interaction between the copolymer (A) and the alkyl group in the fatty acid alkyl ester (C) used in the fuel (preferably a biodiesel fuel, which will be described later), thereby effectively suppressing the crystallization of the fatty acid alkyl ester (C), and enabling the production of a fuel with excellent low-temperature fluidity (low CFPP). Examples of the monomer (b) include (meth)acrylic acid alkyl esters having a linear alkyl group (having 6 to 32 carbon atoms) [for example, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-pentadecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, n-octadecyl (meth)acrylate, n-nonadecyl (meth)acrylate, n-eicosyl (meth)acrylate, n-dodecyl (meth)acrylate, cosyl, n-tetracosyl (meth)acrylate, n-hexacosyl (meth)acrylate, n-octacosyl (meth)acrylate, etc.], alkyl (meth)acrylate esters having a branched alkyl group (having 6 to 32 carbon atoms) other than monomer (c) [for example, isohexyl (meth)acrylate, 2-methylpentyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, isoundecyl (meth)acrylate, isododecyl (meth)acrylate, isotridecyl (meth)acrylate, isotetradecyl (meth)acrylate, isopentadecyl (meth)acrylate, etc.], and the like.As the monomer (b), from the viewpoint of interaction with the fatty acid alkyl ester (C), a (meth)acrylic acid alkyl ester having an alkyl group with 8 to 24 carbon atoms is preferred, and a (meth)acrylic acid alkyl ester having an alkyl group with 10 to 16 carbon atoms is more preferred.

[0019] As the monomer (b), a (meth)acrylic acid ester of a mixture of alkyl alcohols such as Neodol (registered trademark) 23 (a mixture of linear and branched alkyl alcohols having 12 to 13 carbon atoms, manufactured by SHELL) or Neodol (registered trademark) 45 (a mixture of linear and branched alkyl alcohols having 14 to 15 carbon atoms, manufactured by SHELL) may be used.

[0020] The copolymer (A) may contain a monomer other than the above-mentioned monomers (a), (b), and (c) as a constituent monomer. Examples of the monomer other than the monomers (a), (b), and (c) include the following monomers (d) to (n).

[0021] (d) Nitrogen Atom-Containing Vinyl Monomers (d1) Amide Group-Containing Vinyl Monomers Examples of vinyl monomers containing a nitrogen atom only in the amide group include (meth)acrylamide, dialkyl (having 1 to 4 carbon atoms)-substituted (meth)acrylamides [N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-di-n-butyl(meth)acrylamide, etc.], and N-vinylcarboxylic acid amides [N-vinylformamide, N-vinylacetamide, N-vinyl-n- or isopropionylamide, N-vinylhydroxyacetamide, etc.].

[0022] (d2) Nitro group-containing monomers Examples include 4-nitrostyrene, etc. (d3) Primary to Tertiary amino group-containing vinyl monomers Examples include primary amino group-containing vinyl monomers {C3-C6 alkenylamines [(meth)allylamine, crotylamine, etc.], aminoalkyl (C2-C6) (meth)acrylates [aminoethyl (meth)acrylate, etc.]}, secondary amino group-containing vinyl monomers {C1-C6 alkyl aminoalkyl (C2-C6) (meth)acrylates [t-butylaminoethyl methacrylate, methylaminoethyl (meth)acrylate, etc.], diphenylamine (meth)acrylamides [4-diphenylamine (meth)acrylamide, 2-diphenylamine (meth)acrylamide, etc.], C6-C12 dialkenylamines [di(meth)allylamine, etc.]}, and tertiary amino group-containing vinyl monomers {C1-C4 dialkyl aminoalkyl (C2-C6) (meth)acrylates [N , N-dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc.], dialkyl (C1-4) aminoalkyl (C2-6) (meth)acrylamides [dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, etc.]}; tertiary amino group-containing aromatic vinyl monomers (N,N-dimethylaminostyrene, etc.); nitrogen-containing heterocycle-containing vinyl monomers [morpholinoethyl (meth)acrylate, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone, N-vinylthiopyrrolidone, etc.], and their hydrochlorides, sulfates, phosphates, or lower alkyl (C1-8) monocarboxylic acid (acetic acid, propionic acid, etc.) salts.

[0023] (d4) Quaternary Ammonium Base-Containing Vinyl Monomers Examples of the tertiary amino group-containing vinyl monomers include those obtained by quaternizing the tertiary amino group-containing vinyl monomers using a quaternizing agent (such as an alkyl chloride having 1 to 12 carbon atoms, a dialkyl sulfate, a dialkyl carbonate, or benzyl chloride). Specific examples include alkyl (meth)acrylate-based quaternary ammonium salts [(meth)acryloyloxyethyl trimethyl ammonium chloride, (meth)acryloyloxyethyl triethyl ammonium chloride, (meth)acryloyloxyethyl dimethyl benzyl ammonium chloride, or (meth)acryloyloxyethyl methyl morpholino ammonium chloride]; alkyl (meth)acrylamide-based quaternary ammonium salts [(meth)acryloylaminoethyl trimethyl ammonium chloride, (meth)acryloylaminoethyl triethyl ammonium chloride, or (meth)acryloylaminoethyl dimethyl benzyl ammonium chloride]; and other quaternary ammonium base-containing vinyl monomers (such as dimethyl diallyl ammonium methyl sulfate and trimethyl vinyl phenyl ammonium chloride).

[0024] (d5) Amphoteric vinyl monomers: N-(meth)acryloyloxy (or amino) alkyl (C1-10)-N,N-dialkyl (C1-5) ammonium-N-alkyl (C1-5) carboxylate (or sulfate) [N-(meth)acryloyloxyethyl-N,N-dimethylammonium-N-methylcarboxylate, N-(meth)acryloylaminopropyl-N,N-dimethylammonium-N-methylcarboxylate, and N-(meth)acryloyloxyethyl-N,N-dimethylammonium propyl sulfate, etc.]. (d6) Nitrile group-containing monomers: (meth)acrylonitrile, etc.

[0025] (e) Aliphatic Hydrocarbon Vinyl Monomers Examples of such monomers include alkenes having 2 to 20 carbon atoms (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, and octadecene) and alkadienes having 4 to 12 carbon atoms (butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene, and 1,7-octadiene).

[0026] (f) Alicyclic hydrocarbon vinyl monomers Examples of such monomers include cyclohexene, (di)cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, and ethylidenebicycloheptene.

[0027] (g) Aromatic hydrocarbon vinyl monomers Examples of aromatic hydrocarbon vinyl monomers include styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4-crotylbenzene, and 2-vinylnaphthalene.

[0028] (h) Vinyl esters, vinyl ethers, and vinyl ketones Examples of vinyl esters of saturated fatty acids having 2 to 12 carbon atoms (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, etc.), alkyl, aryl, or alkoxyalkyl vinyl ethers having 1 to 12 carbon atoms (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, vinyl-2-methoxyethyl ether, vinyl-2-butoxyethyl ether, etc.), and alkyl or aryl vinyl ketones having 1 to 8 carbon atoms (methyl vinyl ketone, ethyl vinyl ketone, phenyl vinyl ketone, etc.).

[0029] (i) Epoxy Group-Containing Vinyl Monomers Examples include glycidyl (meth)acrylate and glycidyl (meth)allyl ether.

[0030] (j) Halogen-containing vinyl monomers Examples of halogen-containing vinyl monomers include vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride, and halogenated styrenes (such as dichlorostyrene).

[0031] (k) Esters of Unsaturated Polycarboxylic Acids Examples of such esters include alkyl, cycloalkyl, or aralkyl esters of unsaturated polycarboxylic acids [such as C1-C8 alkyl diesters of unsaturated dicarboxylic acids (such as maleic acid, fumaric acid, and itaconic acid) (dimethyl maleate, dimethyl fumarate, diethyl maleate, and dioctyl maleate)].

[0032] (l) Hydroxyl group-containing vinyl monomers Hydroxyl group-containing aromatic vinyl monomers (e.g., p-hydroxystyrene), hydroxyalkyl (C2-6) (meth)acrylates [2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, etc.], mono- or di-hydroxyalkyl (C1-4) substituted (meth)acrylamides [N,N-dihydroxymethyl (meth)acrylamide, N,N-dihydroxypropyl (meth)acrylamide, N,N-di-2-hydroxybutyl (meth)acrylamide, etc.], vinyl alcohol, alkenyl alcohols having 3 to 12 carbon atoms [(meth)allyl alcohol, chloromethyl ... alcohol, isocrotyl alcohol, 1-octenol, 1-undecenol, etc.], alkenediols having 4 to 12 carbon atoms [1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol, etc.], hydroxyalkyl (having 1 to 6 carbon atoms) alkenyl (having 3 to 10 carbon atoms) ethers (2-hydroxyethylpropenyl ether, etc.), alkenyl (having 3 to 10 carbon atoms) ethers or (meth)allyl ethers (sucrose (meth)allyl ether, etc.) of polyhydric (tri- to octahydric) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sugars, sucrose, etc.).

[0033] (m) Polyoxyalkylene Chain-Containing Vinyl Monomers Mono(meth)acrylates of polyoxyalkylene glycols (alkylene group having 2 to 4 carbon atoms, degree of polymerization 2 to 50) {mono(meth)acrylates of polyethylene glycols (number average molecular weight (hereinafter abbreviated as Mn): 100 to 300), mono(meth)acrylates of polypropylene glycols (Mn: 130 to 500), etc.}, polyoxyalkylene polyols [polyoxyalkylene ethers of the above tri- to octahydric polyalcohols (alkylene group having 2 to 4 carbon atoms, degree of polymerization 2 mono(meth)acrylates of alkyl (carbon number 1 to 4) ethers of polyoxyalkylene glycols or polyoxyalkylene polyols [(meth)acrylates of methoxypolyethylene glycols (Mn: 110 to 310), (meth)acrylates of lauryl alcohol ethylene oxide adducts (2 to 30 mol)], and polyoxyethylene sorbitan mono(meth)acrylate (Mn: 150 to 230).

[0034] (n) Ionic Group-Containing Vinyl Monomer (n1) Anionic Group-Containing Vinyl Monomer Examples of anionic group-containing vinyl monomers include monocarboxylic acid group-containing vinyl monomers {unsaturated monocarboxylic acids [(meth)acrylic acid, α-methyl(meth)acrylic acid, crotonic acid, cinnamic acid, etc.], monoalkyl (having 1 to 8 carbon atoms) esters of unsaturated dicarboxylic acids (monoalkyl maleates, monoalkyl fumarate, monoalkyl itaconic acid, etc.)}; dicarboxylic acid group-containing vinyl monomers (maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.);

[0035] (n2) Sulfonic Acid Group-Containing Vinyl Monomers Examples of sulfonic acid group-containing vinyl monomers include alkene sulfonic acids having 2 to 6 carbon atoms [such as vinyl sulfonic acid and (meth)allyl sulfonic acid], aromatic vinyl group-containing sulfonic acids having 6 to 12 carbon atoms [such as α-methylstyrene sulfonic acid], sulfonic acid group-containing (meth)acrylic ester monomers [such as sulfopropyl (meth)acrylate and 2-(meth)acryloyloxyethanesulfonic acid], sulfonic acid group-containing (meth)acrylamide monomers [such as 2-(meth)acrylamido-2-methylpropanesulfonic acid], vinyl monomers containing a sulfonic acid group and a hydroxyl group [such as 3-(meth)acrylamido-2-hydroxypropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and 3-(meth)acryloyloxy-2-hydroxypropanesulfonic acid], and alkyl (having 3 to 18 carbon atoms) allyl sulfosuccinates [such as dodecyl allyl sulfosuccinate].

[0036] (n3) Sulfate Ester Group-Containing Vinyl Monomers Examples of such monomers include sulfate esters of poly(n=2 to 30)oxyalkylene (oxyethylene, oxypropylene, oxybutylene, etc.; addition form may be any of single, random addition, or block addition) mono(meth)acrylates, and sulfate esters of poly(degree of polymerization 2 to 30)oxyalkylene (oxyethylene, oxypropylene, oxybutylene, etc.; addition form may be any of single, random addition, or block addition) bisphenol A mono(meth)acrylates.

[0037] (n4) Phosphate group-containing vinyl monomers Examples of such monomers include (meth)acryloyloxyalkyl (having 2 to 6 carbon atoms) phosphate monoesters [e.g., (meth)acryloyloxyethyl phosphate] and (meth)acryloyloxyphosphonic acids [e.g., 2-acryloyloxyethyl phosphonic acid].

[0038] The weight proportion of monomer (a) among the constituent monomers of copolymer (A) is preferably 5 to 30 wt%, more preferably 5 to 20 wt%, based on the total weight of the constituent monomers, from the viewpoint of crystallization onset temperature. The weight proportion of monomer (b) among the constituent monomers of copolymer (A) is preferably 25 to 90 wt%, more preferably 40 to 85 wt%, based on the total weight of the constituent monomers, from the viewpoint of interaction with fatty acid alkyl ester (C). The weight proportion of monomer (c) among the constituent monomers of copolymer (A) is preferably 5 to 55 wt%, more preferably 5 to 45 wt%, based on the total weight of the constituent monomers, from the viewpoint of handleability. The weight proportion of monomer (d) among the constituent monomers of copolymer (A) is preferably 10 wt% or less, more preferably 3 wt% or less, based on the total weight of the constituent monomers, from the viewpoint of oxidation stability. The weight proportion of monomer (l) among the constituent monomers of copolymer (A) is preferably 10% by weight or less, more preferably 3% by weight or less, based on the total weight of the constituent monomers, from the viewpoint of storage stability. The total weight proportion of monomers (d) to (n) among the constituent monomers of copolymer (A) is preferably 10% by weight or less, more preferably 3% by weight or less, based on the total weight of the constituent monomers, from the viewpoint of the low temperature flow properties (CFPP) of the fatty acid alkyl ester fuel and compatibility with fatty acid alkyl ester (C).

[0039] In the present invention, the weight ratio (a / c) of monomer (a) to monomer (c) among the monomers constituting copolymer (A) is 0.015 to 12.5, preferably 0.090 to 6.0, and more preferably 0.11 to 4.0. If the weight ratio (a / c) is less than 0.015, the low-temperature fluidity of the fatty acid alkyl ester fuel deteriorates (CFPP increases), while if it exceeds 12.5, the handleability of the low-temperature fluidity improver for fatty acid alkyl ester fuel (resistance to solidification at low temperatures) deteriorates.

[0040] In the present invention, the weight ratio (a / b) of the monomer (a) to the monomer (b) among the monomers constituting the copolymer (A) is preferably 0.010 to 10.0, more preferably 0.060 to 1.2, from the viewpoint of the interaction with the fatty acid alkyl ester (C).

[0041] In the present invention, the weight ratio (b / c) of monomer (b) to monomer (c) among the monomers constituting copolymer (A) is preferably 0.075 to 23.8, more preferably 0.45 to 18.0, from the viewpoint of handleability of the cold flow improver for fatty acid alkyl ester fuels (resistance to solidification at low temperatures).

[0042] From the viewpoint of low-temperature fluidity, the crystallization onset temperature (Tcs) of the copolymer (A) is preferably -15 to 10°C, more preferably -13 to 5°C, and particularly preferably -11 to 2°C. In the present invention, the crystallization onset temperature (Tcs) is the crystallization onset temperature observed when a 5 mg sample is cooled from 50°C to -80°C at an isothermal rate of 10°C / min using a differential scanning calorimeter "UNIX (registered trademark) DSC7" (manufactured by PERKIN-ELMER). The crystallization onset temperature (Tcs) is defined as the temperature at the intersection of the descending tangent, which is a tangent passing through the point with the most negative slope in the rising portion from the baseline of the DSC curve to the exothermic peak on the highest temperature side, with the baseline. The crystallization onset temperature of the copolymer (A) can be adjusted by changing the type and amount of monomer. The crystallization onset temperature (Tcs) can be increased by increasing the constituent ratio of a monomer having an alkyl group with a large number of carbon atoms (for example, monomer (b) or monomer (c)). The crystallization onset temperature (Tcs) can be decreased by increasing the constituent ratio of a monomer having an alkyl group with a small number of carbon atoms (for example, monomer (a)), or by copolymerizing other monomers (d) to (n) with low crystallinity.

[0043] The SP value (solubility parameter) of the copolymer (A) is set to 8.5 to 9.3 (cal / cm) from the viewpoint of low-temperature fluidity and compatibility with the fatty acid alkyl ester (C). ３ ) １／２ is preferable, and more preferably 8.7 to 9.2 (cal / cm ３ ) １／２The SP value in the present invention refers to a value calculated by the Fedors method, that is, a value calculated by the formula (28) described on page 153 of Polymer Engineering and Science, February 1974, Vol. 14, No. 2, pp. 147-154, using the values ​​(heat of vaporization and molar volume at 25°C of atoms or functional groups) described on page 152 (Table 5) of the same. Specifically, the SP value can be calculated from the values ​​of Δei and Δvi described in Tables 1-1 and 1-2 below, which are parameters of the Fedors method, by applying the values ​​corresponding to the types of atoms and atomic groups in the molecular structure to the following formula. SP value = (ΣΔe ｉ / ΣΔv ｉ ) １／２ [In the formula, ΣΔe ｉ (unit: cal / mol) is the cohesive energy density (unit: cal / mol), and ΣΔv ｉ is the molecular volume (unit: cm ３ / mol).

[0044]

[0045]

[0046] The SP value of the copolymer (A) means a weighted average value calculated by calculating the SP value of the structural units (structures in which vinyl groups have become single bonds through a polymerization reaction) derived from each monomer constituting the copolymer (A) using the above-mentioned SP value calculation method, based on the weight fraction of each structural monomer at the time of charging. For example, when the monomer is methyl methacrylate, the structural unit derived from methyl methacrylate has, as an atomic group, CH ３ 2 pieces, CH ２ 1, 1 C, CO ２ Since there is one unit, the SP value of the structural unit derived from methyl methacrylate is 9.933 (cal / cm ３ ) １／２ It can be seen that ΣΔe ｉ =1125×2+1180+350+4300=8080 ΣΔv ｉ =33.5×2+16.1-19.2+18.0=81.9 δ=(8080 / 81.9) １／２ =9.933(cal / cm３ ) １／２ Similarly, the SP value of the structural unit derived from ethyl methacrylate is 9.721 (cal / cm ３ ) １／２ It can be seen that. When the copolymer is a polymer of 50% by weight of methyl methacrylate and 50% by weight of ethyl methacrylate, the SP value of the copolymer is calculated by taking a weighted average based on the weight fraction of the SP values ​​of the constituent units derived from each monomer, as follows: SP value of copolymer = (9.933 x 50 + 9.721 x 50) / 100 = 9.827 Furthermore, the SP value calculated based on the weight fraction of (A) can be adjusted to the desired range by appropriately adjusting the monomers used and their weight fractions. Specifically, the SP value can be reduced by using a large amount of monomers with alkyl groups having a long carbon number, and the SP value can be increased by using a large amount of monomers with alkyl groups having a short carbon number.

[0047] The weight average molecular weight (hereinafter abbreviated as Mw) of the copolymer (A) is preferably 10,000 to 100,000, more preferably 15,000 to 50,000, from the viewpoints of low-temperature fluidity and compatibility with the fatty acid alkyl ester (C). In the present invention, Mw and number average molecular weight (Mn) can be measured by gel permeation chromatography (hereinafter abbreviated as GPC) under the following conditions. <Conditions for measuring Mw and Mn> Apparatus: "HLC-8320GPC" [manufactured by Tosoh Corporation] Column: Two "TSKgel GMHXL" [manufactured by Tosoh Corporation], and one "TSKgel Multipore H" column. ＸＬ 1 tube of "-M" [manufactured by Tosoh Corporation] Measurement temperature: 40°C Sample solution: 0.25 wt% tetrahydrofuran solution Solution injection amount: 10.0 μl Detector: refractive index detector Reference material: standard polystyrene [TS reference material: standard polystyrene (TSK gel standard POLYSTYRENE)] 12 points (molecular weight: 589, 1,050, 2,630, 9,100, 19,500, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,110,000, 4,480,000) [manufactured by Tosoh Corporation]

[0048] Copolymer (A) can be obtained by known production methods, specifically, a method in which the above-mentioned constituent monomers are solution polymerized in a solvent in the presence of a polymerization catalyst. Examples of solvents include toluene, xylene, alkyl (C3-C10) benzene, methyl ethyl ketone, mineral oil, hydrocarbon oil, ester oil, diesel, and biodiesel fuel. Examples of polymerization catalysts include azo catalysts (such as azobisisobutyronitrile and azobisvaleronitrile) and peroxide catalysts (such as benzoyl peroxide, cumyl peroxide, and lauryl peroxide). If necessary, a chain transfer agent (such as an alkyl mercaptan having 2 to 20 carbon atoms) can also be used. The polymerization temperature is preferably 50 to 140°C, more preferably 70 to 120°C. In addition to the solution polymerization described above, copolymer (A) can also be obtained by bulk polymerization, emulsion polymerization, or suspension polymerization. The polymerization form of copolymer (A) may be either a random addition copolymer or an alternating copolymer, and may also be either a graft copolymer or a block copolymer. The Mw of the copolymer (A) can be adjusted by adjusting the polymerization conditions such as the temperature during polymerization, the monomer concentration (solvent concentration), the amount of catalyst or the amount of chain transfer agent.

[0049] <Cold Flow Improver for Fatty Acid Alkyl Ester Fuels> The cold flow improver for fatty acid alkyl ester fuels of the present invention contains the copolymer (A), and from the viewpoint of handleability, it may be a solution containing the copolymer (A) at a high concentration. When the cold flow improver for fatty acid alkyl ester fuels is a solution containing the copolymer (A) at a high concentration, examples of the base material used include diluent oil (B) {e.g., mineral oil (solvent refined oil, paraffin oil, high viscosity index oil containing isoparaffin, high viscosity index oil obtained by hydrocracking isoparaffin, naphthenic oil, etc.), synthetic lubricating oil [hydrocarbon-based synthetic lubricating oil (poly-α-olefin-based synthetic lubricating oil, etc.), ester-based synthetic lubricating oil, etc.]}, fatty acid alkyl ester (C), etc. From the viewpoint of cost, diluent oil (B) is preferred as the base material, and mineral oil is more preferred. From the viewpoint of handleability, the content of copolymer (A) in the cold flow improver for fatty acid alkyl ester fuels is preferably 30 to 70 wt % based on the weight of the cold flow improver for fatty acid alkyl ester fuels. From the viewpoint of ease of handling, the content of the base in the cold flow improver for fatty acid alkyl ester fuels is preferably 30 to 70% by weight, based on the weight of the cold flow improver for fatty acid alkyl ester fuels.

[0050] The fatty acid alkyl ester fuel composition of the present invention contains the above-mentioned low-temperature fluidity improver for fatty acid alkyl ester fuels and a fatty acid alkyl ester (C). <Fatty acid alkyl ester (C)> Examples of the fatty acid alkyl ester (C) include those used in fuels, such as esters of long-chain fatty acids derived from fats and oils (e.g., mixtures of fatty acids having 8 to 24 carbon atoms, preferably mixtures of fatty acids having 8 to 22 carbon atoms) with fatty alcohols having 1 to 5 carbon atoms (preferably 1 to 3 carbon atoms, more preferably 1 carbon atom). From the viewpoint of ease of production of the fatty acid alkyl ester (C) (reactivity between fatty acids and fatty alcohols), fatty acid methyl esters are preferred as the fatty acid alkyl ester (C).

[0051] Examples of fats and oils include natural oils (e.g., vegetable fats and oils such as rapeseed oil, sesame oil, soybean oil, corn oil, sunflower oil, palm oil, palm kernel oil, coconut oil, safflower oil, rice oil, coconut oil, tung oil, castor oil, safflower oil, peanut oil, cottonseed oil, linseed oil, and mustard oil; animal fats and oils such as beef tallow, pork oil, whale oil, and fish oil; waste cooking oils thereof; dark oils obtained in the production process of these fats and oils; fatty acid derivatives such as monoglycerides, diglycerides, and free fatty acids).

[0052] In the present invention, biodiesel fuel may be used as the fatty acid alkyl ester (C). In the present invention, "biodiesel fuel" refers to a fatty acid alkyl ester produced by esterification or transesterification of natural oils and used to power diesel engines. In some forms, biodiesel fuel is produced by esterifying natural oils with alcohols (e.g., ethanol or methanol) in the presence of a catalyst to form alkyl esters.

[0053] Examples of the fatty acid alkyl ester (C) include one or a mixture of two or more selected from the group consisting of ester compounds formed from a fatty acid having 8 to 24 carbon atoms (preferably 8 to 22 carbon atoms) and an alcohol having 1 to 5 carbon atoms (preferably an alcohol having 1 to 3 carbon atoms).

[0054] In the present invention, the fatty acid alkyl ester (C) is preferably a biodiesel fuel derived from discarded cooking oil (waste cooking oil). Waste cooking oil tends to have a high content of saturated fatty acid components in its fatty acids due to the application of heat, particularly saturated fatty acids with a long carbon number (18 to 22 carbon atoms) that have a higher crystallization temperature. Biodiesel fuel derived from waste cooking oil tends to have a high CFPP. In the present invention, the use of (A) described above can result in a biodiesel fuel with excellent low-temperature fluidity (low CFPP). From the viewpoint of low-temperature fluidity, the proportion of saturated fatty acid alkyl ester components with 8 to 22 carbon atoms (C8 to C22) contained in the fatty acid alkyl ester (C) is preferably 3.0 to 92.0 wt %, more preferably 3.0 to 64.0 wt %, based on the weight of the fatty acid alkyl ester (C). From the viewpoint of low-temperature fluidity, the proportion of the saturated fatty acid alkyl ester component having 18 to 22 carbon atoms (C18 to C22) contained in the fatty acid alkyl ester (C) is preferably 3.0 to 15.0 wt %, more preferably 3.0 to 12.0 wt %, based on the weight of the fatty acid alkyl ester (C).

[0055] In the present invention, when biodiesel fuel is used as the fatty acid alkyl ester (C), there is a high possibility that glycerin fatty acid esters derived from fats and oils are contained as impurities. From the viewpoint of quality stability, the content of glycerin fatty acid esters in the fatty acid alkyl ester (C) is preferably 0.001 to 1.2 wt %, more preferably 0.001 to 1.0 wt %, based on the weight of the fatty acid alkyl ester (C). The content of glycerin fatty acid esters in the fatty acid alkyl ester (C) can be determined by measuring the amounts of fatty acid monoglyceride, fatty acid diglyceride, and fatty acid triglyceride, respectively, in accordance with the descriptions of "5.17 Monoglyceride," "5.18 Diglyceride," and "5.19 Triglyceride" in JIS K 2390:2016, and then totaling them.

[0056] The CFPP of the fatty acid alkyl ester (C) is preferably −7° C. or higher, more preferably −6° C. or higher. When the CFPP of the fatty acid alkyl ester (C) is −7° C. or higher, the low-temperature fluidity improving effect (CFPP reducing effect) tends to be higher when the low-temperature fluidity improver of the present invention is used, which is preferable. The CFPP can be measured in accordance with the description of JIS K 2288:2011, "Light Oil - Filter Plugging Point Test Method."

[0057] <Fatty Acid Alkyl Ester Fuel Composition> From the viewpoint of low-temperature fluidity, the content of the cold flow improver for fatty acid alkyl ester fuel in the fatty acid alkyl ester fuel composition is preferably 0.01 to 5.0 wt %, more preferably 0.05 to 3.0 wt %, and particularly preferably 0.1 to 2.0 wt %, based on the weight of the fatty acid alkyl ester fuel composition. From the viewpoint of low-temperature fluidity and compatibility with the fatty acid alkyl ester (C), the content of the copolymer (A) in the fatty acid alkyl ester fuel composition is preferably 0.05 to 5.0 wt %, more preferably 0.1 to 1.0 wt %, based on the weight of the fatty acid alkyl ester fuel composition. From the viewpoint of low-temperature fluidity, the content of the fatty acid alkyl ester (C) in the fatty acid alkyl ester fuel composition is preferably 49.50 to 99.0 wt %, more preferably 95.0 to 99.9 wt %, based on the weight of the fatty acid alkyl ester fuel composition.

[0058] In the present invention, from the viewpoint of fuel quality, the content of glycerin fatty acid ester in the fatty acid alkyl ester fuel composition is preferably 0.001 to 1.2 wt %, and more preferably 0.001 to 1.0 wt %, based on the weight of the fatty acid alkyl ester fuel composition.

[0059] From the viewpoint of low-temperature fluidity, the absolute value of the difference between the crystallization onset temperature (Tcs) of the copolymer (A) and the CFPP of the fatty acid alkyl ester (C) in the fatty acid alkyl ester fuel composition is preferably 0 to 16°C, more preferably 0 to 5°C.

[0060] From the viewpoint of low-temperature fluidity, the CFPP of the fatty acid alkyl ester fuel composition of the present invention is preferably −10° C. or less, more preferably −15° C. or less. The CFPP of the fatty acid alkyl ester fuel composition is preferably 4° C. or more lower, more preferably 9° C. or more lower, than the CFPP of the fatty acid alkyl ester (C).

[0061] The fatty acid alkyl ester fuel composition of the present invention may contain at least one additive selected from the group consisting of cetane number improvers, detergents, antioxidants, lubricity improvers, metal deactivators, anti-icing agents, corrosion inhibitors, antistatic agents, colorants, water-removing agents, and antifoaming agents.

[0062] Examples of cetane number improvers include aliphatic nitrates such as ethyl nitrate, methoxyethyl nitrate, isopropyl nitrate, amyl nitrate, hexyl nitrate, heptyl nitrate, octyl nitrate, 2-ethylhexyl nitrate, and cyclohexyl nitrate; and peroxides such as di-tert-butyl peroxide, and one or more of these may be used. The content of the cetane number improver is not particularly limited, but is preferably 0.001 to 10% by weight, for example, based on the total amount of the fatty acid alkyl ester fuel composition.

[0063] Examples of detergents include imide compounds; alkenyl succinimides such as polybutenyl succinimide synthesized from polybutenyl succinic anhydride and ethylene polyamines; succinate esters such as polybutenyl succinate ester synthesized from polyhydric alcohols such as pentaerythritol and polybutenyl succinic anhydride; copolymers such as copolymers of alkyl methacrylates with dialkylaminoethyl methacrylate, polyethylene glycol methacrylate, vinylpyrrolidone, etc.; and ashless detergents such as reaction products of carboxylic acids and amines. One or more of these may be used. The content of the detergent is not particularly limited, but is preferably 0.001 to 0.5 wt. % based on the total amount of the fatty acid alkyl ester fuel composition.

[0064] Examples of the antioxidant include amine-based antioxidants such as N,N'-diisopropyl-p-phenylenediamine, N,N'-dibutyl-p-phenylenediamine, N,N'-dioctyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-ditolyl-p-phenylenediamine, and N-tolyl-N'-xylenyl-p-phenylenediamine; 2-t-butylphenol, 2,6-di-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol; and sulfur-based antioxidants such as dilauryl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, laurylstearyl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl β,β'-thiodibutyrate, and dilauryl sulfide, and these antioxidants may be used alone or in combination. The content of the antioxidant is not particularly limited, but is preferably 0.001 to 10 wt. % based on the total weight of the fatty acid alkyl ester fuel composition.

[0065] Examples of lubricity improvers include carboxylic acids such as linoleic acid, oleic acid, and stearic acid, and one or more of these can be used. There are no particular restrictions on the amount of lubricity improver contained, but it is preferably 0.001 to 10% by weight, for example, of the total amount of the fatty acid alkyl ester fuel composition.

[0066] Examples of the metal deactivator include amino compounds such as ethylenediamine; salicylidene compounds such as N,N'-disalicylidene-1,2-diaminopropane, N,N'-disalicylidene-2-cyclohexanediamine, N,N'-disalicylideneethylenediamine, N,N'-bis(dimethylsalicylidene)ethylenediamine, N,N'-bis(dimethylsalicylidene)ethylenetetramine, and salicylaldoxime; 1-[bis(2-ethylhexyl)aminomethyl]-1,2,4-triazole, 1-(1-butoxyethyl)-1,2,4-triazole, 4,4'-methylenebiazole, and the like. and triazole compounds such as bis(2-undecyl-5-methylimidazole) and bis[(N-methyl)imidazol-2-yl]carbinol octyl ether; and benzotriazole compounds such as 4-alkylbenzotriazole, 4,5,6,7-tetrahydrobenzotriazole, 5,5'-methylenebisbenzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, 1-(nonyloxymethyl)benzotriazole, and 1-(1-butoxyethyl)benzotriazole. One or more of these may be used. The content of the metal deactivator is not particularly limited, but is preferably 0.001 to 10% by weight, for example, based on the total amount of the fatty acid alkyl ester fuel composition.

[0067] Examples of anti-icing agents include polyglycol ethers. There are no particular restrictions on the amount of anti-icing agent contained, but it is preferable that the amount be 0.001 to 0.5% by weight based on the total amount of the fatty acid alkyl ester fuel composition.

[0068] Examples of corrosion inhibitors include aliphatic amines and their salts, organic phosphates, organic sulfonates, etc., and one or more of these can be used. The content of the corrosion inhibitor is not particularly limited, but is preferably 0.001 to 10% by weight, for example, based on the total amount of the fatty acid alkyl ester fuel composition.

[0069] Examples of antistatic agents include anionic, cationic, and amphoteric surfactants, and one or more of these may be used. There are no particular restrictions on the amount of antistatic agent contained, but it is preferably 0.001 to 0.5% by weight, based on the total amount of the fatty acid alkyl ester fuel composition.

[0070] Examples of colorants include azo dyes, and one or more of these may be used. There are no particular restrictions on the amount of colorant contained, but it is preferably 0.001 to 0.5% by weight, based on the total amount of the fatty acid alkyl ester fuel composition.

[0071] Examples of water-removing agents include methanol and 2-propanol, and one or more of these may be used. There are no particular restrictions on the content of the water-removing agent, but it is preferably 0.001 to 0.5% by weight, based on the total amount of the fatty acid alkyl ester fuel composition.

[0072] The antifoaming agent may be, for example, a silicon-based compound, and one or more of these may be used. There are no particular restrictions on the amount of antifoaming agent contained, but it is preferably 0.001 to 0.5% by weight, based on the total amount of the fatty acid alkyl ester fuel composition.

[0073] The fatty acid alkyl ester fuel composition of the present invention has excellent flow properties at low temperatures compared to conventional compositions, and is therefore useful as a diesel fuel. The fatty acid alkyl ester fuel composition may be used as a diesel fuel as is, or may be made into a diesel fuel composition containing the fatty acid alkyl ester fuel composition and diesel oil, as described below.

[0074] <Diesel Fuel Composition> The diesel fuel composition of the present invention contains the fatty acid alkyl ester fuel composition and diesel fuel. The diesel fuel composition of the present invention contains diesel fuel commonly used as diesel fuel (such as No. 1 diesel fuel, No. 2 diesel fuel, or No. 3 diesel fuel as standardized in JIS K 2204:2007). The content of the fatty acid alkyl ester fuel composition in the diesel fuel composition is preferably 4.95 to 99.0 wt%, more preferably 29.7 to 99.0 wt%, and particularly preferably 50.5 to 99.0 wt%. From the viewpoint of low-temperature fluidity, the content of the diesel fuel composition is preferably 1.0 to 95.05 wt%, more preferably 1.0 to 70.3 wt%, and particularly preferably 1.0 to 49.5 wt%.

[0075] The diesel fuel composition of the present invention can be suitably used as a biodiesel fuel composition.

[0076] This specification describes the following invention: [1] A cold flow improver for fatty acid alkyl ester fuels, comprising a copolymer (A) containing, as essential constituent monomers, a (meth)acrylic acid alkyl ester monomer (a) having an alkyl group containing 1 to 5 carbon atoms, a monomer (c) represented by the following general formula (1), and a (meth)acrylic acid alkyl ester monomer (b) other than the monomer (c) having an alkyl group containing 6 to 32 carbon atoms, wherein the weight ratio (a / c) of the monomer (a) to the monomer (c) among the monomers constituting the copolymer (A) is 0.015 to 12.5: [In general formula (1), R １ represents a hydrogen atom or a methyl group, R ２ and R ３and each independently represent a linear or branched alkyl group having 8 to 24 carbon atoms.] [2] The cold flow improver for fatty acid alkyl ester fuels according to [1], wherein the weight ratio (a / b) of the monomer (a) to the monomer (b) among the monomers constituting the copolymer (A) is 0.010 to 10.0. [3] The cold flow improver for fatty acid alkyl ester fuels according to [1] or [2], wherein the weight ratio (b / c) of the monomer (b) to the monomer (c) among the monomers constituting the copolymer (A) is 0.075 to 23.8. [4] The cold flow improver for fatty acid alkyl ester fuels according to any of [1] to [3], wherein the weight average molecular weight of the copolymer (A) is 10,000 to 100,000. [5] The cold flow improver for fatty acid alkyl ester fuels according to any one of [1] to [4], wherein the content of the copolymer (A) in the cold flow improver for fatty acid alkyl ester fuels is 30 to 70 wt % based on the weight of the cold flow improver for fatty acid alkyl ester fuels. [6] The cold flow improver for fatty acid alkyl ester fuels according to any one of [1] to [5], further comprising a diluent oil (B). [7] The cold flow improver for fatty acid alkyl ester fuels according to [6], wherein the content of the diluent oil (B) in the cold flow improver for fatty acid alkyl ester fuels is 30 to 70 wt % based on the weight of the cold flow improver for fatty acid alkyl ester fuels. [8] A fatty acid alkyl ester fuel composition comprising the cold flow improver for fatty acid alkyl ester fuels according to any one of [1] to [7] and a fatty acid alkyl ester (C). [9] The fatty acid alkyl ester fuel composition according to [8], wherein the content of the fatty acid alkyl ester (C) in the fatty acid alkyl ester fuel composition is 95.0 to 99.9 wt % based on the weight of the fatty acid alkyl ester fuel composition.

[10] The fatty acid alkyl ester fuel composition according to [8] or [9], wherein the fatty acid alkyl ester (C) is a fatty acid methyl ester.

[11] A diesel fuel composition comprising the fatty acid alkyl ester fuel composition according to any one of [8] to

[10] and diesel.

[0077] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0078] Examples 1 to 30, Comparative Examples 1 to 5 A reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, a dropping funnel, a nitrogen inlet tube, and a pressure reducing device was charged with the bases shown in Tables 2-1 to 2-5 in the amounts shown in Tables 2-1 to 2-5. A separate glass beaker was charged with 100 parts by weight of a monomer blend shown in Tables 2-1 to 2-5, the weight parts by weight of dodecyl mercaptan as a chain transfer agent shown in Tables 2-1 to 2-5, 0.1 parts by weight of 2,2-azobis(2,4-dimethylvaleronitrile), and 0.2 parts by weight of 2,2-azobis(2-methylbutyronitrile), and the mixture was stirred and mixed at 20°C to prepare a monomer solution, which was then charged into the dropping funnel. After nitrogen substitution of the gas phase of the reaction vessel (gas phase oxygen concentration: 100 ppm or less), the entire monomer solution in the dropping funnel was added dropwise over 2 hours while maintaining the temperature of the system at 80 ° C. under sealed conditions. After aging at 85 ° C. for 2 hours from the end of the addition, the temperature was raised to 120-130 ° C., and then the residual monomer was removed under reduced pressure (0.027-0.040 MPa) at the same temperature to obtain cold flow improvers (D-1) to (D-30) and (D'-1) to (D'-5) containing diluent oil and copolymer. The SP values ​​of the obtained copolymers (A-1) to (A-30) and (H-1) to (H-5) were calculated using the method described above, and the Mw and crystallization onset temperature (Tcs) were measured using the method described above. Furthermore, the pour point of the cold flow improver was measured using the method described below. The results are shown in Tables 2-1 to 2-5.

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] The components listed in Tables 2-1 to 2-5 are as follows: (a-1): methyl methacrylate (a-2): n-butyl methacrylate (b-1): n-decyl methacrylate (b-2): n-dodecyl acrylate (b-3): ester of methacrylic acid and Neodol (registered trademark) 23 [dodecyl methacrylate / tridecyl methacrylate = 50 / 50 (wt %), weight ratio = linear C12: branched C12: linear C13: branched C13 = 40:10:40:10, methacrylic acid ester obtained by esterifying Neodol (registered trademark) 23 with methacrylic acid] (b-4): Ester of acrylic acid and Neodol (registered trademark) 45 [tetradecyl acrylate / pentadecyl acrylate = 50 / 50 (wt%), weight ratio = linear C14: branched C14: linear C15: branched C15 = 40:10:40:10, acrylic acid ester obtained by esterifying Neodol (registered trademark) 45 with acrylic acid] (b-5): Ester of methacrylic acid and Neodol (registered trademark) 45 [tetradecyl methacrylate / pentadecyl methacrylate = 50 / 50 (wt%), weight ratio = linear C14: branched C14: linear C15: branched C15 = 40:10:40:10, methacrylic acid ester obtained by esterifying Neodol (registered trademark) 45 with methacrylic acid] (b-6): n-hexadecyl acrylate (b-7): n-hexadecyl methacrylate (b-8): n-octadecyl acrylate (b-9): n-octadecyl methacrylate (b-10): n-eicosyl methacrylate (b-11): n-docosyl acrylate (b-12): n-docosyl methacrylate (c-1): 2-decyltetradecyl methacrylate (c-2): 2-dodecylhexadecyl methacrylate (c-3): 2-tetradecyloctadecyl methacrylate (c-4): 2-octyldodecyl methacrylate (d-1): N,N-dimethylaminoethyl methacrylate (l-1): 2-hydroxyethyl methacrylate (B-1) Mineral oil-1: YUBASE2 (SK Lubricants Co., Ltd., 100 ° C. kinematic viscosity: 2.41 mm ２ / s, 40℃ kinematic viscosity: 8.65mm ２ / s, viscosity index: 96) (B-2) Mineral oil-2: YUBASE3 (SK Lubricants Co., Ltd., kinematic viscosity at 100°C: 3.10 mm ２ / s, 40℃ kinematic viscosity: 12.40mm ２ / s, viscosity index: 112) (B-3) Mineral oil-3: YUBASE4 (SK Lubricants Co., Ltd., kinematic viscosity at 100°C: 4.21 mm ２ / s, 40℃ kinematic viscosity: 19.12mm ２ / s, viscosity index: 126) (B-4) Hydrocarbon oil: Poly-α-olefin base oil (SpectraSyn2 manufactured by Exxon Mobil, kinematic viscosity at 100°C: 1.70 mm ２ / s, 40℃ kinematic viscosity: 5.0mm ２ / s, viscosity index: N / A) (B-5) Ester oil-1: Diester of 2-ethylhexyl alcohol and adipic acid (100°C kinematic viscosity: 2.40 mm ２ / s, 40℃ kinematic viscosity: 7.80mm ２ / s, viscosity index: 135) (B-6) Ester oil-2: diester of 2-ethylhexyl alcohol and dodecanedioic acid (100 kinematic viscosity: 3.70 mm ２ / s, 40℃ kinematic viscosity: 13.70mm ２ / s, viscosity index: 169)

[0085] <Pour point of cold flow improver> Measurement was carried out in accordance with the method described in JIS K 2269: 1987, "Test method for pour point and cloud point of crude oil and petroleum products." A lower temperature means that the cold flow improver for fatty acid alkyl ester fuels is less likely to solidify and is easier to handle, and a pour point of 0°C or less is preferred.

[0086] Examples 31 to 69, Comparative Examples 6 to 11: The low-temperature fluidity improvers (D-1) to (D-30) or (D'-1) to (D'-5) containing the copolymers (A-1) to (A-30) obtained in Examples 1 to 28 or the comparative copolymers (H-1) to (H-5) obtained in Comparative Examples 1 to 3 were blended with the following fuels [fatty acid alkyl esters (C-1) to (C-6) or diesel fuel (C'-1)] as shown in Tables 3-1 to 3-3 and 4-1 to 4-4 to obtain fatty acid alkyl ester fuel compositions (V1) to (V39), (V'1) to (V'6). CFPP tests were performed on the fatty acid alkyl ester fuel compositions (V1) to (V39), (V'1) to (V'6) using the following method. The results are shown in Tables 3-1 to 3-3 and 4-1 to 4-4.

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] The fuels listed in the table [fatty acid alkyl esters (C-1) to (C-6) and diesel fuel (C'-1)] are as follows: Fatty acid alkyl ester (C-1): Biodiesel fuel oil (manufactured by Keinan Clean Co., Ltd., fatty acid methyl ester derived from waste cooking oil, content of saturated fatty acid methyl ester having 18 to 22 carbon atoms: 3.7% by weight Fatty acid alkyl ester (C-2): Biodiesel fuel oil (manufactured by Keinan Clean Co., Ltd., fatty acid methyl ester derived from waste cooking oil, content of saturated fatty acid methyl ester having 18 to 22 carbon atoms: 3.0% by weight Fatty acid alkyl ester (C-3): Biodiesel fuel oil (fatty acid methyl ester derived from waste cooking oil, content of saturated fatty acid methyl ester having 8 to 22 carbon atoms adjusted relative to fatty acid alkyl ester (C-2) by the following method) Fatty acid alkyl ester (C-4): Biodiesel fuel oil (fatty acid methyl ester derived from waste cooking oil, content of saturated fatty acid methyl ester having 8 to 22 carbon atoms adjusted relative to (C-2)) Fatty acid alkyl ester (C-5): Biodiesel fuel oil (fatty acid methyl ester derived from waste cooking oil, content of saturated fatty acid methyl ester having 8 to 22 carbon atoms adjusted relative to (C-2)) Fatty acid alkyl ester (C-6): Biodiesel fuel oil (fatty acid methyl ester derived from waste cooking oil, with the content of saturated fatty acid methyl ester with 8 to 22 carbon atoms adjusted compared to (C-2)) Diesel oil (C'-1): No. 2 diesel oil standardized in JIS K 2204:2007

[0095] <Fatty Acid Alkyl Ester (C-3)> A mixture of methyl caprylate, methyl caprate, methyl laurate, methyl myristate, and methyl palmitate purchased from FUJIFILM Wako Pure Chemical Industries, Ltd. in a ratio of 8.2 wt %:7.1 wt %:55.2 wt %:22.4 wt %:7.1 wt % was used as the saturated fatty acid (C8 to C16) methyl ester, and methyl stearate purchased from FUJIFILM Wako Pure Chemical Industries, Ltd. was used as the saturated fatty acid (C18 to C22) methyl ester. Methyl stearate was added to the fatty acid alkyl ester (C-2) so that the contents of the C18 to C22 and C8 to C22 saturated fatty acid alkyl esters were in the proportions shown in Table 4-2 above, and the mixture was mixed at room temperature to obtain a fatty acid alkyl ester (C-3).

[0096] <Fatty Acid Alkyl Esters (C-4) to (C-6)> Methyl palmitate and methyl stearate, purchased from FUJIFILM Wako Pure Chemical Industries, Ltd., were used as saturated fatty acid (carbon number: 8 to 16) methyl esters and saturated fatty acid (carbon number: 18 to 22) methyl esters, respectively. These were added to the fatty acid alkyl ester (C-2) so that the contents of the C18 to C22 and C8 to C22 saturated fatty acid alkyl esters were in the proportions shown in Tables 4-2 and 4-3 above, and the mixture was mixed at room temperature to obtain fatty acid alkyl esters (C-4) to (C-6).

[0097] <Saturated Fatty Acid Alkyl Ester Content> The C18 to C22 and C8 to C22 saturated fatty acid alkyl ester contents of the fatty acid alkyl ester (C) were measured by an analytical method in accordance with EN14103.

[0098] <CFPP Test> Measurements were carried out for each fuel (fatty acid alkyl ester (C) and diesel (C'-1)) and the fatty acid alkyl ester fuel compositions obtained in the Examples and Comparative Examples in accordance with the method described in JIS K 2288:2011 "Diesel Oil - Clogging Point Test Method." That is, 45 ml of sample was placed in a test tube, cooled, and for each 1°C decrease in sample temperature, the sample was sucked up through a wire mesh filter with a mesh opening of 45 μm under a reduced pressure of 2 kPa (200 mm water column), and the time required for 20 ml of sample to pass through the wire mesh filter was measured. In this way, the temperature was read when the sample's filtration time exceeded 60 seconds, and this was reported as CFPP in Tables 3-1 to 3-3 and 4-1 to 4-4. Furthermore, the difference between the CFPP of the fatty acid alkyl ester (C) alone and the CFPP of the fatty acid alkyl ester fuel composition ("CFPP of fatty acid alkyl ester fuel composition" - "CFPP of fatty acid alkyl ester (C) alone") is shown in Tables 3-1 to 3-3 and Tables 4-1 to 4-4 as the degree of reduction in CFPP of the fatty acid alkyl ester fuel composition. The greater the degree of reduction in CFPP, the better the cold flow improver for fatty acid alkyl ester fuels. The degree of reduction is preferably -5°C or less.

[0099] The low-temperature flow improver for fatty acid alkyl ester fuels of the present invention is resistant to solidification at low temperatures, and the fatty acid alkyl ester fuel composition of the present invention has excellent low-temperature flowability, making it suitable for use in cold regions, etc. Furthermore, the fatty acid alkyl ester fuel composition of the present invention can contain biodiesel fuel, making it suitable for use as a biodiesel fuel composition. Furthermore, the fatty acid alkyl ester fuel composition of the present invention can also be used as a lubricating oil for various machines.

Claims

1. A low-temperature fluidity improver for fatty acid alkyl ester fuels, comprising a copolymer (A) containing as essential constituent monomers (a) a (meth)acrylic acid alkyl ester monomer having an alkyl group of 1 to 5 carbon atoms, a monomer (c) represented by the following general formula (1), and a (meth)acrylic acid alkyl ester monomer (b) other than said monomer (c) having an alkyl group of 6 to 32 carbon atoms, wherein the weight ratio (a / c) of said monomer (a) to said monomer (c) among the monomers constituting said copolymer (A) is 0.015 to 12.

5. [In general formula (1), R １ represents a hydrogen atom or a methyl group, R ２ and R ３ each independently represents a linear or branched alkyl group having 8 to 24 carbon atoms.

2. A low-temperature fluidity improver for fatty acid alkyl ester fuels as described in claim 1, wherein the weight ratio (a / b) of said monomer (a) to said monomer (b) among the monomers constituting said copolymer (A) is 0.010 to 10.

0.

3. A low-temperature fluidity improver for fatty acid alkyl ester fuels as described in claim 1, wherein the weight ratio (b / c) of said monomer (b) to said monomer (c) among the monomers constituting said copolymer (A) is 0.075 to 23.

8.

4. The low-temperature fluidity improver for fatty acid alkyl ester fuels according to claim 1, wherein the weight-average molecular weight of said copolymer (A) is 10,000 to 100,000.

5. The low-temperature fluidity improver for fatty acid alkyl ester fuels according to claim 1, wherein the content of said copolymer (A) in the low-temperature fluidity improver for fatty acid alkyl ester fuels is 30 to 70 weight % based on the weight of the low-temperature fluidity improver for fatty acid alkyl ester fuels.

6. The low-temperature fluidity improver for fatty acid alkyl ester fuels according to claim 1, further comprising a diluent oil (B).

7. The low-temperature fluidity improver for fatty acid alkyl ester fuels according to claim 6, wherein the content of said diluent oil (B) in the low-temperature fluidity improver for fatty acid alkyl ester fuels is 30 to 70 weight % based on the weight of the low-temperature fluidity improver for fatty acid alkyl ester fuels.

8. A fatty acid alkyl ester fuel composition comprising the low-temperature fluidity improver for fatty acid alkyl ester fuels according to any one of claims 1 to 7 and a fatty acid alkyl ester (C).

9. A fatty acid alkyl ester fuel composition according to claim 8, wherein the content of the fatty acid alkyl ester (C) in the fatty acid alkyl ester fuel composition is 95.0 to 99.9% by weight, based on the weight of the fatty acid alkyl ester fuel composition.

10. The fatty acid alkyl ester fuel composition according to claim 8, wherein the fatty acid alkyl ester (C) is a fatty acid methyl ester.

11. A diesel fuel composition comprising the fatty acid alkyl ester fuel composition according to claim 8 and diesel.

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