Patent Grant
7323019
Additives for low-sulfur mineral oil distillates, comprising an ester of an alkoxylated polyol and a polar nitrogen-containing paraffin dispersant
The invention relates to additives for low-sulfur mineral oil distillates having improved cold flowability and paraffin dispersancy, comprising an ester of an alkoxylated polyol and a polar nitrogen-containing paraffin dispersant, to additized fuel oils and to the use of the additive.
In view of the decreasing crude oil reserves coupled with steadily rising energy demand, ever more problematic crude oils are being extracted and processed. In addition, the demands on the fuel oils, such as diesel and heating oil, produced therefrom are becoming ever more stringent, not least as a result of legislative requirements. Examples thereof are the reduction in the sulfur content, the limitation of the final boiling point and also of the aromatics content of middle distillates, which force the refineries into constant adaptation of the processing technology. In middle distillates, this leads in many cases to an increased proportion of paraffins, especially in the chain length range of from C18 to C24, which in turn has a negative influence on the cold flow properties of these fuel oils.
Crude oils and middle distillates, such as gas oil, diesel oil or heating oil, obtained by distillation of crude oils contain, depending on the origin of the crude oils, different amounts of n-paraffins which crystallize out as platelet-shaped crystals when the temperature is reduced and sometimes agglomerate with the inclusion of oil. This crystallization and agglomeration causes a deterioration in the flow properties of these oils or distillates, which may result in disruption, for example, in the course of extraction, transport, storage and/or use of the mineral oils and mineral oil distillates. When mineral oils are transported through pipelines, the crystallization phenomenon can, especially in winter, lead to deposits on the pipe walls, and in individual cases, for example in the event of stoppage of a pipeline, even to its complete blockage. When storing and further processing the mineral oils, it may be necessary in winter to store the mineral oils in heated tanks. In the case of mineral oil distillates, the consequence of crystallization may be blockage of the filters in diesel engines and boilers, which prevents reliable metering of the fuels and in some cases results in complete interruption of the fuel or heating medium feed.
In addition to the classical methods of eliminating the crystallized paraffins (thermal, mechanical or using solvents), which merely involve the removal of the precipitates which have already formed, chemical additives (known as flow improvers or paraffin inhibitors) have been developed in recent years. By interacting physically with the precipitating paraffin crystals, they bring about modification of their shape, size and adhesion properties. The additives function as additional crystal seeds and some of them crystallize out with the paraffins, resulting in a larger number of smaller paraffin crystals having modified crystal shape. The modified paraffin crystals have a lower tendency to agglomerate, so that the oils admixed with these additives can still be pumped and processed at temperatures which are often more than 20° C. lower than in the case of nonadditized oils.
Typical flow improvers for crude oils and middle distillates are co- and terpolymers of ethylene with carboxylic esters of vinyl alcohol.
A further task of flow improver additives is the dispersion of the paraffin crystals, i.e. the retardation or prevention of sedimentation of the paraffin crystals and therefore the formation of a paraffin-rich layer at the bottom of storage vessels.
The prior art also discloses certain poly(oxyalkylene) compounds and also alkylphenol resins which are added as additives to middle distillates.
EP-A-0 061 895 discloses cold flow improvers for mineral oil distillates which comprise esters, ethers or mixtures thereof. The esters/ethers contain two linear saturated C10- to C30-alkyl groups and a polyoxyalkylene group having from 200 to 5000 g/mol.
EP-0 973 848 and EP-0 973 850 disclose mixtures or esters of alkoxylated alcohols having more than 10 carbon atoms and fatty acids having 10-40 carbon atoms in combination with ethylene copolymers as flow improvers.
EP-A-0 935 645 discloses alkylphenol-aldehyde resins as a lubricity-improving additive in low-sulfur middle distillates.
EP-A-0857776 and EP-A-1 088 045 disclose processes for improving the flowability of paraffinic mineral oils and mineral oil distillates by adding ethylene copolymers and alkylphenol-aldehyde resins, and also optionally further, nitrogen-containing paraffin dispersants.
The above-described flow-improving and/or paraffin-dispersing action of the existing paraffin dispersants is not always adequate, so that sometimes large paraffin crystals form when the oils are cooled and lead to filter blockages and, as a consequence of their relatively high density, sediment in the course of time and thus lead to the formation of a paraffin-rich layer at the bottom of the storage vessels. Problems occur in particular in the additization of paraffin-rich and narrow-cut distillation cuts having boiling ranges from 20-90% by volume of less than 120° C., in particular less than 100° C. The situation is particularly problematic in the case of low-sulfur winter qualities having cloud points below −5° C.; the addition of existing additives here often does not lead to adequate paraffin dispersancy.
It is therefore an object of the invention to improve the flowability, and in particular the paraffin dispersancy, in the case of mineral oils and mineral oil distillates, by the addition of suitable additives.
It has been found that, surprisingly, an additive which comprises, in addition to polar nitrogen-containing paraffin dispersants, also certain esters of alkoxylated polyols constitutes a particularly good cold flow improver for low-sulfur fuel oils.
The invention therefore provides additives for middle distillates having a maximum sulfur content of 0.05% by weight, comprising at least one fatty ester of alkoxylated polyols having at least 3 OH groups (A) and at least one polar nitrogen-containing paraffin dispersant (D).
The invention further provides middle distillates having a maximum sulfur content of 0.05% by weight, which comprise an additive which comprises at least one fatty ester of alkoxylated polyols having at least 3 OH groups (A) and at least one polar nitrogen-containing paraffin dispersant (D).
The invention further provides the use of an additive comprising at least one fatty ester of alkoxylated polyols having at least 3 OH groups (A) and at least one polar nitrogen-containing paraffin dispersant (D), for improving the cold flow properties and paraffin dispersancy of middle distillates having a maximum sulfur content of 0.05% by weight.
The invention further provides a process for improving the cold flow properties of middle distillates having a maximum sulfur content of 0.05% by weight, by adding to the middle distillates an additive comprising at least one fatty ester of alkoxylated polyols having at least 3 OH groups (A) and at least one polar nitrogen-containing paraffin dispersant (D).
The esters (A) derive from polyols having 3 or more OH groups, in particular from glycerol, trimethylolpropane, pentaerythritol, and also the oligomers obtainable therefrom by condensation and having from 2 to 10 monomer units, for example polyglycerol. The polyols have generally been reacted with from 1 to 100 mol of alkylene oxide, preferably from 3 to 70 mol, in particular from 5 to 50 mol, of alkylene oxide, per mole of polyol. Preferred alkylene oxides are ethylene oxide, propylene oxide and butylene oxide. The alkoxylation is effected by known processes.
The fatty acids which are suitable for the esterification of the alkoxylated polyols preferably have from 8 to 50, in particular from 12 to 30, especially from 16 to 26, carbon atoms. Suitable fatty acids are, for example, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, magaric acid, stearic acid, isostearic acid, arachic acid and behenic acid, oleic acid and erucic acid, palmitoleic acid, myristoleic acid, ricinoleic acid, and also fatty acid mixtures obtained from natural fats and oils. Preferred fatty acid mixtures contain more than 50% of fatty acids having at least 20 carbon atoms. Preferably, less than 50% of the fatty acids used for esterification contain double bonds, in particular less than 10%; they are especially very substantially saturated. Very substantially saturated means here an iodine number of the fatty acids used of up to 5 g of I per 100 g of fatty acid. The esterification may also be effected starting from reactive derivatives of the acids such as esters with lower alcohols (for example methyl or ethyl esters) or anhydrides.
To esterify the alkoxylated polyols, mixtures of the above fatty acids with fat-soluble, polybasic carboxylic acids may also be used. Examples of suitable polybasic carboxylic acids are dimer fatty acids, alkenylsuccinic acids and aromatic polycarboxylic acids, and also their derivatives such as anhydrides and C1- to C5-esters. Preference is given to alkenylsuccinic acid and its derivatives with alkyl radicals having from 8 to 200, in particular from 10 to 50, carbon atoms. Examples are dodecenyl-, octadecenyl- and poly(isobutenyl)succinic anhydride. Preference is given to using the polybasic carboxylic acids in minor amounts of up to 30 mol %, preferably from 1 to 20 mol %, in particular from 2 to 10 mol %.
Esters and fatty acids are used for the esterification, based on the content of hydroxyl groups on the one hand and carboxyl groups on the other hand, in a ratio of from 1.5:1 to 1:1.5, preferably from 1.1:1 to 1:1.1, in particular equimolar. The paraffin-dispersing action is particularly marked when operation is effected with an acid excess of up to 20 mol %, especially up to 10 mol %, in particular up to 5 mol %.
The esterification is carried out by customary processes. It has been found to be particularly useful to react polyol alkoxylate with fatty acid, optionally in the presence of catalysts, for example para-toluenesulfonic acid, C2- to C50-alkylbenzenesulfonic acids, methanesulfonic acid or acidic ion exchangers. The water of reaction may be removed distillatively by direct condensation or preferably by means of azeotropic distillation in the presence of organic solvents, in particular aromatic solvents, such as toluene, xylene or else relatively high-boiling mixtures such as ®Shellsol A, Shellsol B, Shellsol AB or Solvent Naphtha. The esterification is preferably effected to completion, i.e. from 1.0 to 1.5 mol of fatty acid are used for the esterification per mole of hydroxyl groups. The acid number of the ester is generally below 15 mg KOH/g, preferably below 10 mg KOH/g, especially below 5 mg KOH/g.
The polar nitrogen-containing paraffin dispersants (D) present in the additive according to the invention are low molecular weight or polymeric, oil-soluble nitrogen compounds, for example amine salts, imides and/or amides, which are obtained by reacting aliphatic or aromatic amines, preferably long-chain aliphatic amines, with aliphatic or aromatic mono-, di-, tri- or tetracarboxylic acids or their anhydrides. Particularly preferred paraffin dispersants comprise reaction products of secondary fatty amines having from 8 to 36 carbon atoms, in particular dicoconut fatty amine, ditallow fatty amine and distearylamine. Other paraffin dispersants are copolymers of maleic anhydride and α,β-unsaturated compounds which may optionally be reacted with primary monoalkylamines and/or aliphatic alcohols, the reaction products of alkenyl-spiro-bislactones with amines and reaction products of terpolymers based on α,β-unsaturated dicarboxylic anhydrides, α,β-unsaturated compounds and polyoxyalkylene ethers of lower unsaturated alcohols. Some suitable paraffin dispersants (D) are listed hereinbelow.
Some of the paraffin dispersants (D) specified below are prepared by reacting compounds which contain an acyl group with an amine. This amine is a compound of the formula NR6R7R8 where R6, R7 and R8 may be the same or different, and at least one of these groups is C8- to C36-alkyl, C6-C36-cycloalkyl, C8-C36-alkenyl, in particular C12-C24-alkyl, C12- to C24-alkenyl or cyclohexyl, and the remaining groups are either hydrogen, C1- to C36-alkyl, C2-C36-alkenyl, cyclohexyl, or a group of the formulae -(A-O)x-E or —(CH2)n—NYZ, where A is an ethylene or propylene group, x is a number from 1 to 50, E=H, C1-C30-alkyl, C5-C12-cycloalkyl or C6-C30-aryl, and n is 2, 3 or 4, and Y and Z are each independently H, C1-C30-alkyl or -(A-O)x. An acyl group here is a functional group of the following formula:
>C═O
In a preferred embodiment of the invention, to the additives and fuel oils according to the invention which contains the constituents (A) and (C) may also be added ethylene copolymers (B), alkylphenol-aldehyde resins (C) and/or comb polymers. Preferred embodiments are consequently also fuel oils according to the invention which comprise ethylene copolymers (B), alkylphenol-aldehyde resins (C) and/or comb polymers, and also the use according to the invention of additives which comprise ethylene copolymers (B), alkylphenol-aldehyde resins (C) and/or comb polymers, and the corresponding process.
Copolymer B) is preferably an ethylene copolymer having an ethylene content of from 60 to 90 mol % and a comonomer content of from 10 to 40 mol %, preferably from 12 to 18 mol %. Suitable comonomers are vinyl esters of aliphatic carboxylic acids having from 2 to 15 carbon atoms.
Preferred vinyl esters for copolymer B) are vinyl acetate, vinyl propionate, vinyl hexanoate, vinyl octanoate, vinyl-2-ethylhexanoate, vinyl laurate and vinyl esters of neocarboxylic acids, here in particular of neononanoic, neodecanoic and neoundecanoic acid. Particular preference is given to an ethylene-vinyl acetate copolymer, an ethylene-vinyl propionate copolymer, an ethylene-vinyl acetate-vinyl octanoate terpolymer, an ethylene-vinyl acetate-vinyl 2-ethylhexanoate terpolymer, an ethylene-vinyl acetate-vinyl neononanoate terpolymer or an ethylene-vinyl acetate-vinyl neodecanoate terpolymer. Preferred acrylic esters are acylic esters with alcohol radicals having from 1 to 20, in particular from 2 to 12 and especially from 4 to 8, carbon atoms, for example methyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate. The copolymers may contain up to 5% by weight of further comonomers. Such comonomers may be, for example, vinyl esters, vinyl ethers, alkyl acrylates, alkyl methacrylates having C1- to C20-alkyl radicals, isobutylene and olefins. Preferred as higher olefins are hexene, isobutylene, octene and/or diisobutylene. Further suitable comonomers are olefins such as propene, hexene, butene, isobutene, diisobutylene, 4-methylpentene-1 and norbornene. Particular preference is given to ethylene-vinyl acetate-diisobutylene and ethylene-vinyl acetate-4-methylpentene-1 terpolymers.
The copolymers preferably have melt viscosities at 140° C. of from 20 to 10 000 mPas, in particular from 30 to 5000 mPas, especially from 50 to 2000 mPas.
The copolymers (B) can be prepared by the customary copolymerization processes, for example suspension polymerization, solution polymerization, gas phase polymerization or high pressure bulk polymerization. Preference is given to high pressure bulk polymerization at pressures of preferably from 50 to 400 MPa, in particular from 100 to 300 MPa, and temperatures of preferably from 50 to 350° C., in particular from 100 to 250° C. The reaction of the monomers is initiated by radical-forming initiators (radical chain starters). This substance class includes, for example, oxygen, hydroperoxides, peroxides and azo compounds, such as cumene hydroperoxide, t-butyl hydroperoxide, dilauroyl peroxide, dibenzoyl peroxide, bis(2-ethylhexyl) peroxide carbonate, t-butyl perpivalate, t-butyl permaleate, t-butyl perbenzoate, dicumyl peroxide, t-butyl cumyl peroxide, di-(t-butyl) peroxide, 2,2′-azobis(2-methylpropionitrile), 2,2′-azobis(2-methylbutyronitrile). The initiators are used individually or as a mixture of two or more substances in amounts of from 0.01 to 20% by weight, preferably from 0.05 to 10% by weight, based on the monomer mixture.
The high pressure bulk polymerization is carried out in known high pressure reactors, for example autoclaves or tubular reactors, batchwise or continuously, and tubular reactors have been found to be particularly useful. Solvents such as aliphatic and/or aromatic hydrocarbons or hydrocarbon mixtures, benzene or toluene may be present in the reaction mixture. Preference is given to working without solvent. In a preferred embodiment of the polymerization, the mixture of the monomers, the initiator and, where used, the moderator are fed to a tubular reactor via the reactor inlet and also via one or more side branches. The monomer streams may have different compositions (EP-A-0 271 738).
Suitable co- or terpolymers include, for example:
The ethylene copolymers may be used individually or as a mixture with different types of polymer.
The alkylphenol-aldehyde resins (C) are known in principle and are described, for example, in Römpp Chemie Lexikon, 9th edition, Thieme Verlag 1988-92, volume 4, p. 3351 ff. The alkyl radicals of the o- or p-alkyl-phenol have 1-50, preferably 4-20, in particular 6-12, carbon atoms; they are preferably n-, iso- and tert-butyl, n- and isopentyl, n- and isohexyl, n- and isooctyl, n- and isononyl, n- and isodecyl, n- and isododecyl, and also tetrapropenyl, pentapropenyl and polyisobutenyl. The alkylphenol-aldehyde resin may also contain up to 50 mol % of phenol units. For the alkylphenol-aldehyde resin, identical or different alkylphenols may be used. The aliphatic aldehyde in the alkylphenol-aldehyde resin has 1-10, preferably 1-4, carbon atoms, and may bear further functional groups such as aldehyde or carboxyl groups. It is preferably formaldehyde. The molecular weight of the alkylphenol-aldehyde resins is 400-10000 g/mol, preferably 400-5000 g/mol. A prerequisite is that the resins are oil-soluble.
The alkylphenol-aldehyde resins are prepared in a manner known per se by basic catalysis to form condensation products of the resol type or by acidic catalysis to form condensation products of the novolak type.
The condensates obtained in both ways are suitable for the compositions according to the invention. Preference is given to condensing in the presence of acidic catalysts.
To prepare the alkylphenol-aldehyde resins, a bifunctional o- or p-alkyl-phenol having from 1 to 50 carbon atoms, preferably from 4 to 20, in particular from 6 to 12, carbon atoms, per alkyl group, or mixtures thereof, and an aliphatic aldehyde having from 1 to 10 carbon atoms are reacted together, using 0.5-2 mol, preferably 0.7-1.3 mol and in particular equimolar amounts, of aldehyde per mole of alkylphenol compound.
Suitable alkylphenols are in particular C4- to C50-alkylphenols, for example o- or p-cresol, n-, sec- and tert-butylphenol, n- and i-pentylphenol, n- and isohexylphenol, n- and isooctylphenol, n- and isononylphenol, n- and isodecylphenol, n- and isododecylphenol, tetradecylphenol, hexadecylphenol, octadecylphenol, eicosylphenol, tripropenylphenol, tetrapropenylphenol and poly(isobutenyl)phenol.
The alkylphenols are preferably para-substituted. Preferably at most 7 mol %, in particular at most 3 mol %, of them are substituted by more than one alkyl group.
Particularly suitable aldehydes are formaldehyde, acetaldehylde, butyraldehyde and glutaraldehyde; preference is given to formaldehyde.
The formaldehyde may be used in the form of paraformaldehyde or in the form of a preferably 20-40% by weight aqueous formalin solution. Appropriate amounts of trioxane may also be used.
Alkylphenol and aldehyde are typically reacted in the presence of alkaline catalysts, for example alkali metal hydroxides or alkylamines, or of acidic catalysts, for example inorganic or organic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, sulfonic acid, sulfamido acids or haloacetic acids, and in the presence of an organic solvent which forms an azeotrope with water, for example toluene, xylene, higher aromatics or mixtures thereof. The reaction mixture is heated to a temperature of from 90 to 200° C., preferably 100-160° C., and the water of reaction formed during the reaction is removed by azeotropic distillation. Solvents which do not release any protons under the conditions of the condensation may remain in the products after the condensation reaction. The resins may be used directly or after neutralization of the catalyst, optionally after further dilution of the solution with aliphatic and/or aromatic hydrocarbons or hydrocarbon mixtures, for example benzine fractions, kerosene, decane, pentadecane, toluene, xylene, ethylbenzene or solvents such as ®Solvent Naphtha, ®Shellsol AB, ®Solvesso 150, ®Solvesso 200, ®Exxsol, ®ISOPAR and ®Shellsol D types.
The alkylphenol resins may subsequently optionally be alkoxylated by reacting with from 1 to 10 mol, especially from 1 to 5 mol, of alkylene oxide such as ethylene oxide, propylene oxide or butylene oxide, per phenolic OH group.
Finally, in a further embodiment of the invention, the additives and middle distillates according to the invention may contain comb polymers. This refers to polymers in which hydrocarbon radicals having at least 8, in particular at least 10, carbon atoms are bonded to a polymer backbone. These are preferably homopolymers whose alkyl side chains have at least 8 and in particular at least 10 carbon atoms. In copolymers, at least 20%, preferably at least 30%, of the monomers have side chains (cf. Comb-like Polymers-Structure and Properties; N. A. Platé and V. P. Shibaev, J. Polym. Sci. Macromolecular Revs. 1974, 8, 117 ff). Examples of suitable comb polymers are, for example, fumarate/vinyl acetate copolymers (cf. EP 0 153 176 A1), copolymers of a C6-C24-α-olefin and an N-C6-C22-alkylmaleimide (cf. EP 0 320 766), and also esterified olefin/maleic anhydride copolymers, polymers and copolymers of a-olefins and esterified copolymers of styrene and maleic anhydride.
Comb polymers can be described, for example, by the formula
In this structure,
The mixing ratio (in parts by weight) of the additives according to the invention with paraffin dispersants, resins and comb polymers is in each case from 1:10 to 20:1, preferably from 1:1 to 10:1.
The additive components according to the invention may be added to mineral oils or mineral oil distillates separately or in a mixture. In a preferred embodiment, the individual additive constituents or else the corresponding mixture are dissolved or dispersed in an organic solvent or dispersant before the addition to the middle distillates. The solution or suspension generally contains 5-90% by weight, preferably 5-75% by weight, of the additive or additive mixture.
Suitable solvents or dispersants in this context are aliphatic and/or aromatic hydrocarbons or hydrocarbon mixtures, for example benzine fractions, kerosene, decane, pentadecane, toluene, xylene, ethylbenzene or commercial solvent mixtures such as Solvent Naphtha, ®Shellsol AB, ®Solvesso 150, ®Solvesso 200, ®Exxsol, ®ISOPAR and ®Shellsol D types. Polar solubilizers such as 2-ethylhexanol, decanol, isodecanol or isotridecanol may optionally also be added.
Mineral oils or mineral oil distillates having cold properties improved by the additives according to the invention contain from 0.001 to 2% by weight, preferably from 0.005 to 0.5% by weight, of the additives, based on the mineral oil or mineral oil distillate.
The additives according to the invention are especially suitable for improving the cold flow properties of animal, vegetable or mineral oils. At the same time, they improve the dispersancy of the precipitated paraffins below the cloud point. They are particularly suitable for use in middle distillates. Middle distillates refer in particular to those mineral oils which are obtained by distilling crude oil and boil in the range from 120 to 450° C., for example kerosene, jet fuel, diesel and heating oil. Preference is given to using the additives according to the invention in low-sulfur middle distillates which contain 350 ppm of sulfur and less, more preferably less than 200 ppm of sulfur and in particular less than 50 ppm of sulfur. The additives according to the invention are also preferably used in those middle distillates which have 95% distillation points below 365° C., especially 350° C. and in special cases below 330° C., and contain high contents of paraffins having from 18 to 24 carbon atoms but only small fractions of paraffins having chain lengths of 24 and more carbon atoms. They may also be used as components in lubricant oils.
The mineral oils and mineral oil distillates may also comprise further customary additives, for example dewaxing auxiliaries, corrosion inhibitors, antioxidants, lubricity additives, sludge inhibitors, cetane number improvers, detergency additives, dehazers, conductivity improvers or dyes.
The following esters A) were used as a 50% solution in aromatic solvent (EO stands for ethylene oxide; PO stands for propylene oxide):
Characterization of the Ethylene Copolymers Used as Flow Improvers (Constituent B)
The viscosity was measured to ISO 3219/B using a rotational viscometer (Haake RV20) having a cone-and-plate measuring system at 140° C.
The additives are used as 50% solutions in Solvent Naphtha or kerosene to improve the ease of handling.
Characterization of the alkylphenol-aldehyde Resins Used (Constituent C))
The boiling parameters were determined to ASTM D-86, the CFPP value to EN 116 and the cloud points to ISO 3015.
Effectiveness of the Additives
In Table 4, the superior effectiveness compared to the prior art of the additives according to the invention together with ethylene copolymers for mineral oils and mineral oil distillates is described with reference to the CFPP test (Cold Filter Plugging Test to EN 116).
The paraffin dispersancy in middle distillates was determined in short sedimentation test as follows:
150 ml of the middle distillates specified in the table, admixed with additive components, in 200 ml measuring cylinders were cooled in a cold cabinet at −2° C./hour to −13° C. and stored at this temperature for 16 hours. Subsequently, volume and appearance, both of the sedimented paraffin phase and the supernatant oil phase, were determined and assessed. A small amount of sediment with a simultaneously homogeneous cloudy oil phase or a large volume of sediment with a clear oil phase show good paraffin dispersancy. In addition, the lower 20% by vol. was isolated and the cloud point determined to ISO 3015. Only a small deviation of the cloud point of the lower phase (CPCC) from the blank value of the oil shows good paraffin dispersancy.
| Number | Date | Country | Kind |
|---|---|---|---|
| 101 55 774 | Nov 2001 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP02/12232 | 11/2/2002 | WO | 00 | 5/12/2004 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO03/042336 | 5/22/2003 | WO | A |
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| 20050005507 A1 | Jan 2005 | US |
