Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/143—Organic compounds mixtures of organic macromolecular compounds with organic non-macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/16—Hydrocarbons
  • C10L1/1691—Hydrocarbons petroleum waxes, mineral waxes; paraffines; alkylation products; Friedel-Crafts condensation products; petroleum resins; modified waxes (oxidised)
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/192—Macromolecular compounds
  • C10L1/195—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C10L1/196—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and a carboxyl group or salts, anhydrides or esters thereof homo- or copolymers of compounds having one or more unsaturated aliphatic radicals each having one carbon bond to carbon double bond, and at least one being terminated by a carboxyl radical or of salts, anhydrides or esters thereof
  • C10L1/1966—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and a carboxyl group or salts, anhydrides or esters thereof homo- or copolymers of compounds having one or more unsaturated aliphatic radicals each having one carbon bond to carbon double bond, and at least one being terminated by a carboxyl radical or of salts, anhydrides or esters thereof poly-carboxylic
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/192—Macromolecular compounds
  • C10L1/195—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C10L1/197—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and an acyloxy group of a saturated carboxylic or carbonic acid
  • C10L1/1973—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and an acyloxy group of a saturated carboxylic or carbonic acid mono-carboxylic
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/192—Macromolecular compounds
  • C10L1/198—Macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds homo- or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon to carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid
  • C10L1/1985—Macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds homo- or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon to carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid polyethers, e.g. di- polygylcols and derivatives; ethers - esters
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/22—Organic compounds containing nitrogen
  • C10L1/222—Organic compounds containing nitrogen containing at least one carbon-to-nitrogen single bond
  • C10L1/224—Amides; Imides carboxylic acid amides, imides

Definitions

• This invention relates to fuel oil additives and to fuel oils containing such additives.
• Heating oils and other distillate petroleum fuels e.g. diesel fuels
• the lowest temperature at which the fuel will still flow is generally known as the pour point.
• the pour point When the fuel temperature reaches or goes below the pour point and the fuel is no longer freely flowable, difficulty arises in transporting the fuel through flow lines and pumps, as for example when attempting to transfer the fuel from one storage vessel to another by gravity or under pump pressure or when attempting to feed the fuel to a burner. Additionally, the wax crystals that have come out of solution tend to plug fuel lines, screens and filters.
• Effective wax crystal modification (as measured by CFPP (Cold Filter Plugging Point) and other operability tests, as well as by cold climate chassis dynanometer and obviously field performance) can be achieved by flow improvers, mostly ethylene-vinyl acetate copolymer (EVA) based, in distillates containing up to 5% -n-paraffin at 10°C below cloud point, as determined by gravimetric or DSC methods. Additive response in these distillates is normally stimulated by adjusting ASTM D-86 distillation characteristics of these distillates (increase of [FBP - 90%] above 20°C and distillation range [90 - 20]% distillation to values above 100°C, FBP above 355°C).
• EVA ethylene-vinyl acetate copolymer
• an additive suitable for adding to a fuel oil comprises a fused mixture of (A) a paraffin wax containing 20 to 45 carbon atoms per molecule and (B) a flow improver.
• Component (A) of the fused mixture is a paraffin wax containing 20 to 45 carbon atoms per molecule. In practice this will almost inevitably comprise a mixture of paraffins of different chain lengths.
• the paraffin mix is preferably an n-alkane or a mixture of n-alkanes, but branched chain alkanes can be used.
• Suitable paraffin waxes are those having 25 to 35 carbon atoms per molecule.
• a typical paraffin wax for use as component (A) has the following composition: % by weight Paraffin 0.028 C20 0.245 C21 1.309 C22 3.750 C23 7.118 C24 8.730 C25 9.996 C26 8.847 C27 8.083 C28 6.769 C29 5.703 C30 4.343 C31 3.533 C32 2.520 C33 1.788 C34 1.093 C35 0.655 C36 0.361 C37 0.190 C38 0.078 C39 0.044 C40
• the hydrocarbon contents were determined by Gas Liquid Chromatography (GLC).
• Component (B) is a flow improver.
• the flow improver is an additive which when added to diesel or heating oil at concentrations of between 0.01 and 0.3 wt% interacts with the crystallising waxes and allows fuel to flow, or pass filters, at a temperature which would not be possible in its absence.
• Suitable tests for measuring flow improvement are CFPP, slow cool filterability tests (eg PCT), Pour Point, vehicle operability, crystal size measurements etc.
• a flow improver produces a ⁇ CFPPT(°C) of at least 1°C, normally several degress when subjecting a fuel containing between 0.01 and 0.3 wt% of the flow improver to the cold filter plugging point test (CFPPT).
• a flow improver very often produces smaller crystals than observed in the base fuel which results in the treated fuel passing finer meshes eg PCT range of filters, (at least one mesh better) than untreated fuel.
• flow improver treated fuel between 0.01 and 0.3 wt%) will pass at least a 60 mesh filter.
• CMPPT Cold Filter Plugging Point Test
• the periodic tests are each initiated by applying a vacuum to the upper end of the pipette whereby oil is drawn through the screen up into the pipette to a mark indicating 20 ml. of oil.
• the test is repeated with each one degree drop in temperature until the oil fails to fill the pipette to a mark indicating 20 ml of oil.
• the test is repeated with each one degree drop in temperature until the oil fails to fill the pipette within 60 seconds.
• the Filterability Test is as follows:-
• the 120 mesh (Mesh No 7) is indicative of good operability.
• the pour point test is similar to CFPP in that the fuel samples undergo rapid cooling.
• the fuel samples (approx 45 ml) are cooled using a series of baths of different temperature.
• the fluidity of the sample is monitored every 3°C until no flow is observed when the fuel sample is titled through 90°C for 5 seconds.
• the temperature 3°C below which no flow occurs is reported as the pour point of the sample.
• flow improver (B) can be one of the following:
• the unsaturated comonomers from which the linear copolymer (i) are derived and which may be copolymerized with ethylene include unsaturated mono and diesters of the general formula: wherein R2 is hydrogen or methyl; R1 is a -OOCR4 group or hydrocarbyl wherein R4 is hydrogen or a C1 to C28, more usually C1 to C17, and preferably a C1 to C8 straight or branched chain alkyl groups or R1 is a -COOR4 group wherein R4 is as previously described but is not hydrogen and R3 is hydrogen or -COOR4 as previous defined.
• the monomer when R1 and R3 are hydrogen and R2 is -OOCR4 includes vinyl alcohol esters of C1 to C29, more usually C1 to C18 monocarboxylic acid, and preferably C2 to C5 monocarboxylic acid.
• vinyl esters which may be copolymerized with ethylene include vinyl acetate, vinyl propionate and vinyl butyrate or isobutyrate, vinyl acetate being preferred.
• the copolymers contain from 20 to 40 wt % of the vinyl ester more preferably from 25 to 35 wt% vinyl ester. They may also be mixtures of two copolymers such as those described in United States patent No 3961916.
• the group R7 is preferably C1 to C28, more usually C1 to C17 and more preferably a C1 to C8 straight or branched chain alkyl group.
• R5 and R6 are preferably hydrogen and R8 a C1 to C20 alkyl group.
• suitable olefins are propylene, hexene-1, octene-1, dodecene-1 and tetradecene-1.
• the ethylene content is 50 to 65 weight per cent although higher amount can be used eg 80 weight % for ethylene - propylene copolymers.
• these copolymers have a number average molecular weight as measured by vapour phase osmometry of 1000 to 6000, preferably 1000 to 3000.
• Particularly suitable linear copolymeric flow improvers (i) are copolymers of ethylene and a vinyl ester.
• the vinyl ester can be a vinyl ester of a monocarboxylic acid, for example one containing 1 to 20 carbon atoms per molecule.
• Examples are vinyl acetate, vinyl propionate and vinyl butyrate. Most preferred however is vinyl acetate.
• the copolymer of ethylene and a vinyl ester will consist of 3 to 40, preferably 3 to 20, molar proportions of ethylene per molar proportion of the vinyl ester.
• the copolymer usually has a number average molecular weight of between 1000 and 50,000, preferably between 1,500 and 5,000. The molecular weights can be measured by cryoscopic methods or by vapour phase osmometry, for example by using a Mechrolab Vapour Phase Osmometer Model 310A.
• linear copolymeric flow improvers are (i) copolymers of an ester of fumaric acid and a vinyl ester.
• the ester of fumaric acid can be either a mono- or a di-ester and alkyl esters are preferred.
• the or each alkyl group can contain 6 to 30, preferably 10 to 20 carbon atoms, and mono- or di- (C14 to C18) alkyl esters are especially suitable, either as single esters or as mixed esters. Generally di-alkyl esters are preferred to mono- esters.
• Suitable vinyl esters with which the fumarate ester is copolymerised are those described above in connection with ethylene/vinyl ester copolymers. Vinyl acetate is particularly preferred.
• the fumarate esters are preferably copolymerised with the vinyl ester in a molar proportion of between 1.5:1 and 1:1.5, for example about 1:1.
• These copolymers usually have a number average molecular weight of from 1000 to 100,000, as measured for example by Vapour Phase Osmometry such as by a Mechrolab Vapour Pressure Osmometer.
• such polymers include a dialkyl fumarate/vinyl acetate copolymer eg ditetradecyl fumarate/vinyl copolymer; a styrene dialkyl maleate ester copolymer eg styrene/dihexadecyl maleate copolymer; a poly dialkyl fumarate, eg poly (di octadecyl fumarate); an ⁇ -olefin dialkyl maleate copolymer eg copolymer of tetradecene and di hexadecyl maleate, a dialkyl itaconate/vinyl acetate copolymer eg dihexadecyl itaconate/vinyl acetate; poly-(n-alkyl methacrylates) eg poly(tetradecyl methacrylate); poly (n-alkyl acrylates) eg poly (
• Linear polymer derived from ethylene oxide (ii) include the poly oxyalkylene esters, ethers, esters/ethers, amide/esters and mixtures thereof, particularly those containing at least one, preferably at least two C10 to C30 linear saturated alkyl groups of a polyoxyalkylene glycol group of molecular weight 100 to 5,000, preferably 200 to 5,000, the alkylene group in said polyoxyalkylene glycol containing from 1 to 4 carbon atoms.
• European patent publication No 0,061,985 A2 describe some of these additives.
• esters, ethers or ester/ethers may be structurally depicted by the formula: R-O-(A)-O-R1 where R and R1 are the same or different and may be
• Suitable glycols generally are the substantially linear polyethylene glycol (PEG) and polypropylene glycols (PPG) having a molecular weight of about 100 to 5,000, preferably about 200 to 2,000.
• Esters are preferred and fatty acids containing from 10-30 carbon atoms are useful for reacting with the glycols to form the ester additives and it is preferred to use a C18-C24 fatty acid, especially behenic acids.
• the esters may also be prepared by esterifying polyethoxylated fatty acids or polyethoxylated alcohols.
• Examples of the monomeric compounds (iv) as flow improver include an amine salt of, a mono amide or a diamide of, or a half amine salt, half amide of a dicarboxylic acid, tricarboxylic acid or anhydride thereof.
• the preferred acid is an aromatic acid, such as the dicarboxylic acids, phthalic acid and 2:3 naphthalene dicarboxylic acid.
• Aliphatic acids such as maleic acid or alkyl or alkenyl succinic acid may be used.
• An example of a tricarboxylic acid is citric acid.
• the amine salt or half amine salt can be derived from a primary, secondary or tertiary amine but the amide can only be derived from a primary or secondary amine.
• the amines are preferably aliphatic amines and the amine is preferably a secondary amine in particular an aliphatic secondary amine of the formula R1R2NH.
• R1 and R2 which can be the same or different contain at least 10 carbon atoms, especially 12 to 22 carbon atoms, e.g. dodecyl, tetradecyl, octadecyl, eicosyl and docosyl (behenyl).
• a particularly preferred compound is the half amine salt, half amide of the dicarboxylic acid in which the amine is a secondary amine.
• the half amine salt, half amide of phthalic acid and dihydrogenated tallow amine - Armeen 2HT (approx 4 wt% n-C14 alkyl, 30 wt% n-C16 alkyl, 60 wt% n-C18 alkyl, the remainder being unsaturated.
• the mixture of (A) and (B) is fused so that the mixture becomes a substantially homogeneous mixture.
• This can be conveniently achieved by heating the mixture of (A) and (B) slowly with stirring until the highest melting component has melted. Thereafter the mixture is allowed to cool and a solid mass of a substantially homogeneous mixture of (A) and (B) will be obtained.
• the exact temperatures will depend on the melting point of the components but usually heating to between 65°C and 75°C is sufficient and the mixture usually becomes solid at a temperature of between 45°C and 55°C.
• any of compounds (1), (2) and (3) can be mixed with (A) as a solution in a solvent.
• the weight ratio of (A) to (B) can vary but weight ratios of 1:1 to 20:1 are suitable, e.g. 8:1 to 12:1, for example about 10:1.
• the fused mixture can be allowed to cool in moulds providing the desired shape of additive mixture or it can be allowed to cool in a large area mould and cut up into smaller pieces later.
• Various shapes include for example slabs, blocks, pastilles, cubes and cuboids.
• the additive of this invention is suitable for adding to a fuel oil and the fuel oil is preferably one in which there is less than 0.5 weight % of fuel oil containing paraffins having a carbon chain length of more than 25 carbon atoms.
• the fuel oil can be for example a distillate fuel.
• the distillate fuel can be the middle distillate fuel oils, e.g. a diesel fuel, aviation fuel, kerosene, fuel oil, jet fuel, heating oil etc.
• suitable distillate fuels are those boiling in the range of 120° to 500°C (ASTM D1160), preferably those boiling in the range 150°C to 400°C.
• Heating oils are preferably made of a blend of virgin distillate, e.g. gas oil, naphtha, etc and cracked distillates, e.g. catalytic cycle stock.
• a representative specification for a diesel fuel includes a minimum flash point of 38°C and a 90 percent distillation point between 282°C and 338°C. (See ASTM Designations D-396 and D-975).
• the fuel oil for which the additive of this invention is particularly suited is a distillate fuel containing between 5 and 10 wt% of wax at 10°C below cloud point.
• Such distillate fuels usually have a narrow carbon distribution, i.e. fuels in which less than 0.2 weight % of the fuel contains paraffins longer than C27.
• a typical distillate fuel containing 5 to 10 wt% wax at 10°C below cloud point has the following ASTM D-86 characteristics: Initial Boiling Point 213°C 5.0% 235°C 10.0% 244°C 20.0% 256°C 30.0% 263°C 40.0% 279°C 50.0% 289°C 60.0% 299°C 70.0% 303°C 80.0% 321°C 90.0% 335°C 95.0% 344°C Final Boiling Point 361°C
• the amount of wax is usually about 8 weight percent at 10°C below cloud point.
• a suitable fuel oil composition comprises a major proportion by weight of a fuel oil and 0.05 to 5.0% by weight of a mixture of (A) a paraffin wax containing 20 to 45 carbon atoms per molecule and (B) a flow improver.
• Also in accordance with this invention is the use as a cold flow improver in a fuel oil of a fused mixture of (A) a paraffin wax containing 20 to 45 carbon atoms per molecule and a flow improver.
• the fused mixture is usually added in a proportion of between 0.05 and 5.0 wt%, e.g. between 0.1 and 2.0 wt% based on the weight of fuel.
• the wax (A) was a mixture of n-alkanes and had the following composition: % by weight Paraffin 0.028 C20 0.245 C21 1.309 C22 3.750 C23 7.118 C24 8.730 C25 9.996 C26 8.847 C27 8.083 C28 6.769 C29 5.703 C30 4.343 C31 3.533 C32 2.520 C33 1.788 C34 1.093 C35 0.655 C36 0.361 C37 0.190 C38 0.078 C39 0.044 C40
• the hydrocarbon contents were determined by Gas Liquid Chromatography (GLC).
• the first flow improver (B1) was a mixture of ethylene/vinyl acetate copolymers and fumarate ester/vinyl acetate copolymers. It consisted of 63.2 weight % of an ethylene/vinyl acetate copolymer containing 36 weight % of vinyl acetate units, 20.8 weight % of an ethylene/vinyl acetate copolymer containing 13 weight % of vinyl acetate units, 9.4 weight % of ditetradecyl fumarate/vinyl acetate copolymer and 6.5 weight % of the diester of fumaric acid/vinyl acetate copolymer in which the ester is derived from a mixture of tetradecyl and hexadecyl alcohols.
• the second flow improver (B2) was a mixture of 93 weight %of an ethylene/vinyl acetate copolymer containing 36 weight % of vinyl acetate units and 7 weight % of an ethylene/vinyl acetate copolymer containing 13 weight % of vinyl acetate units.

Landscapes

• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Liquid Carbonaceous Fuels (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10624023

Family Applications (1)

Country Status (7)

Cited By (19)

Families Citing this family (4)

Citations (11)

• 1987
  • 1987-09-18 GB GB878722016A patent/GB8722016D0/en active Pending
• 1988
  • 1988-09-12 NZ NZ226138A patent/NZ226138A/xx unknown
  • 1988-09-13 EP EP88308455A patent/EP0308176A1/en not_active Withdrawn
  • 1988-09-16 KR KR1019880012026A patent/KR890005250A/ko not_active Application Discontinuation
  • 1988-09-16 AU AU22365/88A patent/AU2236588A/en not_active Abandoned
  • 1988-09-17 CN CN88106736A patent/CN1032184A/zh active Pending
  • 1988-09-19 JP JP63234665A patent/JPH01158096A/ja active Pending

Patent Citations (11)

Also Published As

Similar Documents

Legal Events