Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/39—Organic or inorganic per-compounds
  • C11D3/3945—Organic per-compounds
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/39—Organic or inorganic per-compounds
  • C11D3/3902—Organic or inorganic per-compounds combined with specific additives
  • C11D3/3937—Stabilising agents
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/39—Organic or inorganic per-compounds
  • C11D3/3902—Organic or inorganic per-compounds combined with specific additives
  • C11D3/3937—Stabilising agents
  • C11D3/394—Organic compounds

Definitions

• the present invention is related to a peroxyacid bleach granule and a process for converting a water-wet mixture of materials comprising a peroxyacid bleach and exothermic control materials to a stabilized dry granule.
• the present invention relates to a dry, peroxyacid bleach granule composition and a novel process for making it comprising: spraying wet peroxyacid bleach onto dry granular components of the dry bleach composition in a suitable mixer under controlled conditions.
• the present invention provides a dry agglomerated bleach granule which comprises a complex mixture of peroxyacid bleach and a stabilizing amount of a solid peroxyacid bleach exotherm control agent.
• the present invention also provides a process for making the agglomerated bleach granule.
• agglomeration means forming a particulate by coating, sticking and mixing including forming a dough-like intermediate and combinations thereof.
• the granule of the present invention has a complex crystal­line containing structure as opposed to the spherical particles or flakes as disclosed in the prior art, e.g., U.S. Pat. Nos.: 4,091,544 and 4,497,757, both supra.
• the process is an energy saver over the prior art, ensures better bleach granule uniformity, removes water from a wet per­oxyacid bleach intermediate without exotherming and with less degradation.
• the process of the present invention comprises the following steps:
• the granule has a free moisture content of less than about 0.5% for stability and flowability.
• the density of the granules of this invention are at least about 0.5 gm/cc.
• the preferred density is from about 0.6 to about 0.7 gm/cc.
• Prior art granules prepared by prilling have densities of 0.35 gm/cc to 0.45 gm/cc, well below 0.5 gm/cc.
• the preferred free moisture content of the granule of this invention is from about 0.1% to about 0.3%.
• the preferred level of water in Step A is from about 30% to about 40%.
• the preferred moisture content in Step B is from about 12% to about 18%.
• the preferred final free moisture content of the granules in Step C is from about 0.1% to about 0.3%.
• the average mixing time of Step B is brief, preferably from about 0.2 seconds to about 5 seconds.
• the drying time of Step C in a fluid bed dryer is preferably from about 10 minutes to about 60 minutes.
• the preferred drying inlet air temperature of Step C is from about 35°C to about 100°C, keeping the temperature of the wet granules below about 60°C.
• controlled temperature in Step C means a tem­perature below a bleach destabilizing temperature.
• the preferred temperature of the slurry of Step A is from about 30°C to a maximum of about 40°C.
• the more preferred process temperatures for Step A are from about 34°C to about 38°C, and for Step C is from about 38°C to about 82°C.
• the drying is preferably conducted in a fluid bed dryer.
• pumpable means that the slurry can be introduced into a mechanical mixer containing dry particulate components as a stream or a spray.
• the level of peroxyacid bleach in the dry bleach granule is preferably from about 10% to about 35%, more preferably from about 20% to about 30%, by weight of the granule.
• the peroxyacid can be any suitable peroxyacid.
• suitable organic peroxyacids are disclosed in U.S. Pat. No. 4,374,035, F. P. Bossu, issued Feb. 15, 1983; and U.S. Pat. No. 4,770,666, A. D. Clauss, issued Sept. 13, 1988, both incorporated herein by reference.
• the peroxyacid bleach is used at a level which provides an amount of available oxygen (AvO) of from about 0.1% to about 10%, preferably from about 0.5% to about 5%, and most preferably from about 1% to about 4%.
• a preferred bleach granule comprises 1% to 50% of an exotherm control agent (e.g., boric acid); 3% to 25% of a peroxyacid compatible surfactant (e.g., C13LAS); 0.01% to 10% of one or more chelant stabilizers (e.g., sodium pyrophosphates); and 10% to 50% of a water-soluble processing salt (e.g., Na2SO4).
• an exotherm control agent e.g., boric acid
• a peroxyacid compatible surfactant e.g., C13LAS
• chelant stabilizers e.g., sodium pyrophosphates
• a water-soluble processing salt e.g., Na2SO4
• a preferred peroxyacid bleach is used at a level which provides an amount of available oxygen (AvO) of from about 1.2% to about 5%, preferably from about 2% to about 4%, and most preferively from about 2.5% to about 3.5%.
• AvO available oxygen
• a preferred peroxyacid material for use in the present process is a normally solid peroxyacid compound.
• a compound is "normally solid” if it is in dry or solid form at room tempera­ture.
• Such peroxyacid compounds are the organic peroxyacids and water-soluble salts thereof which in aqueous solution yield a species containing a -O-O- moiety.
• These materials have the general formula HO - O - - R - Y wherein R is an alkylene group containing from 1 to about 20 carbon atoms or a phenylene group and Y is hydrogen, halogen, alkyl, aryl or any group which provides an anionic moiety in aqueous solution.
• Such Y groups can include, for example, - C - M, - - O - OM or - - OM wherein M is H or a water-soluble, salt-forming cation.
• aromatic peroxyacids and salts thereof include monoperoxyphthalic acid, diperoxyterephthalic acid, 4-chlorodiperoxyphthalic acid, the monosodium salt of diperoxy­terephthalic acid, m-chloroperoxybenzoic acid, p-nitroperoxy­benzoic acid, and diperoxyisophthalic acid.
• the most preferred for use in the instant process are diperoxydodecanedioic acid, nonyl­amideperoxysuccinic acid (NAPSA), and diperazelaic acid.
• Step A Preparing the peroxyacid wet mix of Step A and reducing the water content of the peroxyacid wet mix in Step B and the drying of the wet bleach granules of Step C, all require care. It is desirable to remove virtually all of the water from the wet granule in the drying Step C so as to improve the available oxygen stability of the peroxyacid.
• the mixing temperatures and the mix compositions of Steps A and B and the air temperature of Step C must be controlled and must not be allowed to reach a point where exotherm or substantial degradation accords. Thus, it is neces­sary that steps be taken to ensure that the mixing and drying temperatures do not allow the peroxyacid to exothermally decom­pose.
• an agent is put into the mixture which releases water at about the exotherm point of the bleach and thereby controlling it. Agents of this type will be discussed subsequently.
• the time of exposure to the drying temperature is variable depending on the temperature chosen, the materials, the thickness of the individual particles and the drying technique, but will generally be from about several minutes to several hours at a temperature of from about 25°C to about 100°C, preferably from about 60°C to about 70°C, as long as the temperature of the bleach granule itself does not exceed about 60°C.
• the tem­perature of the drying bleach granules is kept below about 55°C.
• the actual unit used for this final drying can be any which does not involve the particles pressing together.
• peroxyacids are susceptible to a number of different stability problems, as well as being likely to cause some problems. Looking at the latter first, peroxyacids decompose exothermally and when the material is in dry granular form the heat generated must be controlled to make the product safe.
• the best exotherm control agents are those which are capable of liberating moisture at a temperature slightly below the decomposition temperature of the peroxyacid employed.
• U.S. Pat. No. 3,770,816, Nielsen, issued Nov. 6, 1973, incorporated herein by reference discloses a wide variety of hydrated materials which can serve as suitable exotherm control agents.
• magnesium sulfate .7H2O magnesium formate dihydrate, calcium sulfate (CaSO4.2H2O), calcium lactate hydrate, calcium sodium sulfate (CaSO4.2Na2SO4.2H2O), and hydrated forms of such things as sodium aluminum sulfate, potassium aluminum sulfate, ammonium aluminum sulfate, and aluminum sulfate.
• Preferred hydrates are the alkali metal aluminum sulfates, particularly preferred is potassium aluminum sulfate.
• Other exotherm control agents include "hydrates" of other suitable salts. The preferred exotherm control agents are those materials which lose water as the result of chemical decomposition such as boric acid, malic acid and maleic acid.
• the exotherm control agent is preferably used in a stabil­izing amount of from about 70% to about 400%, more preferably of from about 75% to about 200%, and most preferably from about 100% to about 150%, based on the type and weight of the peroxyacid compound and the type of control agent used.
• a preferred chelating system for the present invention is a mixture of dipicolinic acid, and an acid polyphosphate, preferably acid sodium pyrophosphate.
• the acid polyphosphate can be a mixture of phosphoric acid and sodium pyrophosphate wherein the ratio of the former to the latter is from about 0.5:1 to about 2:1 and the ratio of the mixture to dipicolinic acid is from about 0.2:1 to abut 5:1.
• Additional agents which may be used to aid in giving good bleaching performance include such things as pH adjustment agents, bleach activators and minors such as coloring agents, dyes and perfumes.
• Typical pH adjustment agents are used to alter or maintain aqueous solutions of the instant compositions within the 5 to 10 pH range in which peroxyacid bleaching agents are gen­erally most useful.
• pH adjustment agents can be either of the acid or base type.
• acidic pH adjustment agents designed to compensate for the presence of other highly alkaline materials include normally solid organic and inorganic acids, acid mixtures and acid salts.
• Such acidic pH adjustment agents include citric acid, glycolic acid, tartaric acid, gluconic acid, glutamic acid, sulfamic acid, sodium bisulfate, potassium bisulfate, ammonium bisulfate, and mixtures of citric acid and lauric acid.
• Citric acid is preferred by virtue of its low toxicity and hardness sequestering capability.
• Optional alkaline pH adjustment agents include the conven­tional alkaline buffering agents.
• buffering agents include such salts as carbonates, bicarbonates, silicates, pyrophosphates and mixtures thereof.
• Sodium bicarbonate and tetrasodium pyrophosphate are highly preferred.
• Optional ingredients if utilized in combination with the active peroxyacid/exothermic material system of the instant invention to form a complete bleaching product, comprise from about 50% to about 95% by weight of the total composition. Conversely, the amount of bleaching system is from about 5% to about 50% of the composition.
• Optional ingredients such as the metal chelating agent is preferably mixed with the peroxyacid and the exothermic control agent in Step A or Step B, thereby becoming a part of the dry units formed in the process.
• Others such as the pH adjustment agents are added as separate particles in Step B or admixed with the granules of this invention.
• Such other ingre­dients may be coated with, for example, an inert fatty material if the ingredients are likely to cause degradation of the peroxyacid.
• bleaching compositions as described above can be added to and made a part of conventional fabric laundering detergent compositions.
• optional materials for the instant bleaching compositions can include such standard detergent adju­vants as surfactants and builders.
• Optional surfactants are selected from the group consisting of organic anionic, nonionic, ampholytic and zwitterionic surfactants and mixtures thereof.
• Optional builder materials include any of the conventional organic builder salts including carbonates.
• Water-soluble salts of the higher fatty acids i.e., "soaps" are useful as the anionic surfactant herein.
• anionic surfactants includes water-soluble salts, particularly the alkali metal, ammonium and alkanolammonium salts, of organic sulfuric reaction products having in their molecular structure an alkyl group containing from about 8 to about 22 carbon atoms and a sulfonic acid or sulfuric acid ester group. (Included in the term “alkyl” is the alkyl portion of acyl groups.)
• Preferred water-soluble anionic organic surfactants herein include linear alkyl benzene sulfonates containing from about 11 to 14 carbon atoms in the alkyl group; the tallow range alkyl sulfates; the coconut range alkyl glyceryl sulfonates; and alkyl ether sulfates wherein the alkyl moiety contains from about 14 to 18 carbon atoms and wherein the average degree of ethoxylation varies between 1 to 6.
• Specific preferred anionic surfactants for use herein include: sodium linear C10-C12 alkyl benzene sulfonate; tri­ethanolamine C10-C12 alkyl benzene sulfonate; sodium tallow alkyl sulfate; sodium coconut alkyl glyceryl ether sulfonate; and the sodium salt of a sulfated condensation product of tallow alcohol with from about 3 to about 10 moles of ethylene oxide.
• anionic surfactants can be used separately herein or as mixtures.
• compositions can also comprise those detergency builders commonly taught for use in laundry com­positions.
• Useful builders herein include any of the conventional inorganic and organic water-soluble builder salts, as well as various water-insoluble and so-called "seeded" builders.
• Inorganic detergency builders useful herein include, for example, water-soluble salts of phosphates, pyrophosphates, orthophosphates, polyphosphates, phosphonates, carbonates, bi­ carbonates, borates and silicates. Examples of these and other phosphorus builder compounds are disclosed in U.S. Pat. Nos. 3,159,581; 3,213,030; 3,422,021; 3,422,137; 3,400,176 and 3,400,148, incorporated herein by reference. Sodium tripoly­phosphate is an especially preferred, water-soluble inorganic builder herein.
• Non-phosphorous containing sequestrants can also be selected for use herein as detergency builders.
• Specific examples of non-phosphorus, inorganic builder ingredients include water-­soluble inorganic carbonate, bicarbonate, borate and silicate salts.
• the alkali metal, e.g., sodium and potassium, carbonates, bicarbonates, borates (Borax) and silicates are particularly useful herein.
• Water-soluble organic builders are also useful herein.
• Highly preferred non-phosphorous builder materials include sodium carbonate, sodium bicarbonate, sodium silicate, sodium citrate, sodium oxydisuc­cinate, sodium mellitate, sodium nitrilotriacetate, and sodium ethylenediaminetetraacetate, and mixtures thereof.
• Another type of builder useful herein includes various substantially water-insoluble materials which are capable of reducing the hardness content of laundering liquors, e.g., by ion-exchange processes.
• the complex aluminosilicates i.e., zeolite-type materials
• zeolite-type materials are useful presoaking/washing adjuvants herein in that these materials soften water, i.e., remove Ca++ hardness.
• zeolite materials and a method of preparation appears in Milton, U.S. Pat. No. 2,882,243, issued April 14, 1959, incorporated herein by reference.
• the bleach granules of this invention can be used with soil release agents. Any suitable soil release agent can be used including those disclosed in U.S. Pat. No. 4,770,666, supra , incorporated herein by reference.
• Step B any dry materials used in Step B as part of the "dry feed," including excess exothermic control agent materials, builders, etc., are referred to herein as "fillers" unless otherwise specified.
• the peroxyacid bleach granules of the present invention can be admixed with other compatible granular bleach and/or detergent composition materials.
• the particle sizes of the bleach con­taining granules or optional granular material are not critical. However, commercially acceptable flow properties having certain granule size limitations are highly preferred.
• the granules of the instant compositions preferably range in size from about 100 microns to 3,000 microns, more preferably from about 100 microns to 1,300 microns, and most preferably from about 250 microns to about 1,000 microns.
• Bleaching compositions of the present invention are utilized by dissolving them in water in an amount sufficient to provide from about 1.0 ppm to 100 ppm available oxygen in solution. Generally, this amounts to from about 0.01% to 0.2% by weight of composition in solution. Fabrics to be bleached are then con­tacted with such aqueous bleaching solutions.
• a dry granular peroxyacid bleach composition is prepared using the following: Wet Peroxyacid Bleach Slurry Parts Diperoxydodecanedioic acid (DPDA) 22.9%; water 46%; boric acid 25.2%; surfactant paste + minors 5.9% 0.93 Dry Feed Solids Anhydrous sodium sulfate 0.35 Recycled dry DPDA fines 2.95 Total 4.23
• the equipment used is a Bepex 8" TC8 Turbulizer mixer and an Aeromatic batch type, fluid bed dryer Model STREA-1 made by Aeromatic AG, Muttenz.
• the wet peroxyacid bleach slurry is prepared by adding the boric acid and the surfactant paste + minors to the aqueous solution of diperoxydodecanedioic acid.
• the recycled dry feed DPDA fines and sodium sulfate are blended in the proportions shown and introduced into the Tur­bulizer mixer.
• the dry feed solids temperature is about 18°C.
• the size of the DPDA fines is under 250 microns and the size of the sulfate is between about 180 microns and 285 microns.
• the wet slurry (30°C) is metered from a tank and sprayed using an air atomized nozzle onto the dry feed solid components in the Turbulizer mixer.
• the exiting material, in the form of wet granules, is collected and transferred to the Aeromatic dryer.
• the temperature of the wet granules out of the Turbulizer mixer is about 30°C.
• the wet granules are therein dried and the dried bleach granules are cooled down in the dryer.
• the final bleach granules are then analyzed for density, particle size and chemical composition.
• the speed, blade angle, and clearance in the Turbulizer mixer are adjusted during the experiments to optimize granule size.
• the wet granules are dried with about 65°C air for about 30 minutes and then cooled to about 18°C in the dryer.
• a description of the dried peroxyacid bleach granules of Example 1 follows: moisture about 0.2%; density about 0.64 gm/cc; percent DPDA about 25%; percent boric acid about 27%; and sodium sulfate about 46%. About 90% of the granules have a particle size in the range of from about 250 microns to about 1,750 microns; and an average particle size of about 500, ⁇ 75 microns.
• the surfactant paste and minors composition for Example 1 is as follows: Ingredient Parts LAS (Linear alkylbenzene sulfonate 28%; sulfate 22%; water 50%) 34.26 Dipicolinic acid (DPA) 0.09 Phosphoric acid (H3PO4) 0.2 Trisodium phosphate (TSPP) 0.11 Total 34.46
• LAS Linear alkylbenzene sulfonate 28%; sulfate 22%; water 50%
• DPA Dipicolinic acid
• H3PO4 Phosphoric acid
• TSPP Trisodium phosphate
• the three minors (DPA, H3PO4 and TSPP) are premixed with the LAS paste in the proportions shown.
• the anhydrous sodium sulfate acts as a filler and also serves as a secondary exothermic control agent/heat sink.
• the equipment used is a Bepex 8" TC8 Turbulizer Mixer and a Bepex 1 sq. meter continuous fluid bed dryer.
• the process and equipment are similar to those of Example 1, except that a continuous fluid bed dryer is used.
• the wet peroxyacid bleach slurry (30°C) is prepared by adding the boric acid and the surfactant paste + minors to the aqueous solution of diperoxydodecanedioic acid.
• the wet slurry (30°C) is metered from a tank and sprayed using an air atomized nozzle onto the dry solid components (ambient temperature) in the Turbulizer mixer.
• Wet granules from the Turbulizer mixer are fed continuously to the Bepex fluid bed dryer.
• the drying air to the first two zones of the Bepex fluid bed is about 65°C.
• the temperature of the drying granules is controlled and kept to less than about 30°C during the drying.
• a third zone of the Bepex is supplied with ambient air to cool the dried bleach.
• Final dried bleach granules have a moisture of about 0.3%; a density of about 0.61 gm/cc; DPDA 24%; boric acid about 28%; and sodium sulfate about 42.5%.
• the sulfate and boric acid solids of Example 2 are fed separately using volumetric feeders.
• the recycled dry bleach fines, which are produced in the fluid bed dryer (Step C), are separated from the desired particle size granules and recycled to the mixer of Step B as dry feed solids.
• the bleach granules in the dryer which are below about 250 microns in size are continu­ously removed from the dryer.
• the dry bleach granular particles over about 1,750 microns in size are screened out and ground up to less than about 250 microns and then recycled as dry solid fines in Step B in the dry feed.
• Example 2 the bed is seeded with either recycled peroxyacid bleach fines or ground bleach granules from a previous run.
• the seeding fines, granules and other dry bleach solid components have particle sizes preferably below 250 microns.
• the process is preferably started up using formulated proportions of particulate boric acid and sulfate as dry feed and mixing the dry feed with the peroxyacid slurry.
• the first bleach granules are recycled from the dryer discharge until the target material balance is reached. Drying air temperature is from about 60°C to about 70°C.
• the equipment used is a Bepex 8" TC8 Turbulizer Mixer and a Bepex 3 sq. meter continuous fluid bed dryer.
• the wet peroxyacid bleach slurry is prepared by adding the boric acid and the surfactant paste + minors to the aqueous solution of diperoxydodecanedioic acid.
• the temperature of the wet slurry is about 30°C.
• the wet slurry is metered from a tank and sprayed using an air atomized nozzle onto the dry feed solids in the Turbulizer mixer.
• the anhydrous sodium sulfate and boric acid solids are fed separately using volumetric feeders.
• Recycled dry DPDA fines which are produced in the fluid bed dryer and separated from the desired particle size granules are added to the Tur­bulizer mixer as dry feed solids.
• Dryer residence time for the drying bleach granules is about 30 minutes.
• the temperature of the dry bleach granules leaving the dryer is about 22°C.
• Their free moisture content is about 0.3%.
• Their density is about 0.63 gm/cc.
• DPDA content is about 26%
• Their boric acid content is about 28.4%; and their sodium sulfate content is about 42.5%.
• Their average particle size is about 500.
• the product yield for Example 3 is about 34% on a dry basis.
• the target peroxyacid concentration in Example 3A is about 10% dry basis (using sulfate as a dry diluent).
• the yield is about 81.9% on a dry basis (See Table 1, Example 3A).
• Example 3B The target peroxyacid concentration of Example 3B is 24% on a dry basis.
• the peroxyacid slurry moisture content is 32%.
• the product yield is 78.95% on a dry basis (See Table 1, Example 3B).
• TABLE 1 Example 3 Example 3A Ingredient Parts Parts Parts Peroxyacid slurry 2.99 2.99 4.87 (Slurry % moisture) (52.2) (52.2) (32) Anhydrous sodium sulfate 1.52 6.51 3.52 Boric acid 0.61 0.61 1.41 Recycled fines/overs* 6.88 1.89 2.20 Totals 12.00 12.00 12.00 Dry yield parts 10.44 10.44 10.44 Yield (dry basis) 34.1% 81.9% 78.95% % Peroxyacid 24 10 24 * The drying process when in equilibrium typically produces 15% to 25% recycle as fines/oversize material.
• DPDA fines composition An appropriate recycled DPDA fines composition for Examples 1, 2 and 3 is: Diperoxydodecanedioic acid (DPDA) 24% Sodium sulfate 43% Boric acid 26% LAS paste 5.2% Minors (includes Na2SO4 in paste) 1.3% Free moisture 0.5%
• Surfactant paste and minors compositions for Examples 2 and 3 are as follows: Ingredient Parts LAS (Linear alkylbenzene sulfonate 50%; sulfate 1%; water 49%) 19.58 Dipicolinic acid (DPA) 0.09 Phosphoric acid (H3PO4) 0.2 Trisodium phosphate (TSPP) 0.11 Total 19.98
• the three minors (DPA, H3PO4 and TSPP) are premixed with the LAS paste in the proportions shown.
• the DPA, TSPP and H3PO4 are added to the formulation as chelating agents to tie up heavy metal ions.
• the LAS is used as a processing aid.
• the temperatures of the wet granules in Step C for all examples are estimated to be below about 30°C.
• the yield out of the dryer is from about 75% to about 85%.
• About 5% to about 10% are overs which are ground to DPDA fines and recycled.
• About 10% to about 15% of the wet granules are pulled out of the dryer as fines via an exhaust bag house collection system.

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• 1990
  • 1990-04-26 EP EP19900304584 patent/EP0396341A3/de not_active Withdrawn
  • 1990-04-26 CA CA 2015490 patent/CA2015490A1/en not_active Abandoned
  • 1990-04-30 MX MX2051290A patent/MX173060B/es unknown
  • 1990-04-30 AU AU54549/90A patent/AU643206B2/en not_active Ceased
  • 1990-05-01 JP JP11571690A patent/JPH03800A/ja active Pending
  • 1990-05-01 CN CN 90102598 patent/CN1046932A/zh active Pending
  • 1990-05-02 BR BR909002050A patent/BR9002050A/pt not_active Application Discontinuation
  • 1990-05-02 MA MA22093A patent/MA21830A1/fr unknown

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