AU7448496A - Acid resistant calcium carbonate filler - Google Patents
Acid resistant calcium carbonate fillerInfo
- Publication number
- AU7448496A AU7448496A AU74484/96A AU7448496A AU7448496A AU 7448496 A AU7448496 A AU 7448496A AU 74484/96 A AU74484/96 A AU 74484/96A AU 7448496 A AU7448496 A AU 7448496A AU 7448496 A AU7448496 A AU 7448496A
- Authority
- AU
- Australia
- Prior art keywords
- acid
- calcium carbonate
- mixture
- weak acids
- dry weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/10—Treatment with macromolecular organic compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/02—Compounds of alkaline earth metals or magnesium
- C09C1/021—Calcium carbonates
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/69—Water-insoluble compounds, e.g. fillers, pigments modified, e.g. by association with other compositions prior to incorporation in the pulp or paper
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
- C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
- C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/675—Oxides, hydroxides or carbonates
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Paper (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Dental Preparations (AREA)
Description
ACID RESISTANT CALCIUM CARBONATE FILLER
RΆΠ Γ.ROTTND OF THE INVENTION
This invention relates generally to calcium carbonate for use in papermaking, and related industries, and more particularly to a calcium carbonate having acid resistant properties- Titanium dioxide and calcined clay have traditionally been utilized as filler materials in the preparation of neutral to weakly acidic paper in order to improve the optical properties, especially the brightness, of the resultant product. These materials, however, especially titanium dioxide, have the disadvantage of being very expensive, resulting in higher manufacturing costs and an uncompetitively priced paper product .
Calcium carbonate, particularly precipitated calcium carbonate, has been used as a filler material in the making of alkaline paper. Such usage results in a paper with enhanced optical properties, without the expense incurred in using titanium oxide fillers, resulting in a much less expensive product. Calcium carbonate, however, cannot generally be used as a filler in acidic paper because it decomposes in an acidic environment. Consequently, there has long been a need to develop a calcium carbonate composition which is acid stabilized and resistant to decomposition at low pH, so that it can be utilized as a filler material in the manufacture of acidic paper, such as groundwood paper, where the use of an alkaline filler would have a negative impact on the final paper properties.
Paper made from mechanical pulps has been traditionally produced under acidic papermaking conditions because of "fiber alkaline darkening" that occurs as pH rises. This means that there is a reduction in brightness of the paper (brightness reversion) when
the pH is raised from acid to alkaline in wood-containing systems. Alkaline darkening will occur to some degree in any wood pulps with significant lignin content. The degree of darkening depends on the particular pulps, Ph, and water quality. In general, ground calcium carbonate and precipitated calcium carbonate fillers buffer wet end in the 7.5-8.2 pH range. Acid-resistant calcium carbonate compositions thus provide a means for reducing the degree of fiber alkaline darkening and brightness reversion due to their ability to maintain a stabilized pH.
U. S. Patent 5,043,017 discloses and claims an acid- stable calcium carbonate resistant to degradation in a mildly acidic environment which comprises a mixture of a calcium-chelating agent or a conjugate base, and a weak acid, such that calcium carbonate is coated by, and is in equilibrium with, the calcium-chelating agent or conjugate base and the weak acid. Preferred calcium carbonate compositions contain sodium hexametaphosphate and phosphoric acid.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide stabilized and acid resistant calcium carbonate compositions especially suitable for use in papermaking applications.
It is a further object of the present invention to provide a process for the preparation of the aforesaid calcium carbonate compositions.
A still further object of the present invention is to provide a paper having enhanced optical qualities prepared using the calcium carbonate compositions of the present invention.
SUMMARY OF THE INVENTION
The present invention relates to an improved form of calcium carbonate which is stabilized and thus, acid resistant, to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid resistant calcium carbonate. More particularly, this invention concerns an acid resistant calcium carbonate consisting essentially of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of two or more weak acids, in admixture with the calcium carbonate. It has surprisingly been found that the inclusion of the mixture of two or more weak acids confers a higher degree of stability and acid resistance for calcium carbonate in the presence of fiber slurry, and a longer term of pH stability than the prior art acid-stabilized calcium carbonate compositions. BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a graph comparing the 24 hours ageing of scalenohedral precipitated calcium carbonate compositions of the present invention containing 1, 2 or 6% polyacrylate acid, and various concentrations of phosphoric acid.
FIGURE 2 is a graph comparing the 24 hours ageing of rhombic precipitated calcium carbonate compositions of the present invention containing 1% or 2% polyacrylate acid, and various concentrations of phosphoric acid.
FIGURE 3 is a graph comparing the 24 hours ageing of ground precipitated calcium carbonate compositions of the present invention containing 1% or 2% polyacrylate acid, and various concentrations of phosphoric acid.
FIGURE 4 is a graph showing the pH of a scalenohedral precipitated calcium carbonate composition of the present invention containing 3% polyacrylate acid, and 5% phosphoric acid.
FIGURE 5 is a graph showing the pH of a scalenohedral precipitated calcium carbonate composition of the present invention containing 1% polymaleic acid, and 4% phosphoric acid. FIGURE 6 is a graph showing the pH of a scalenohedral precipitated calcium carbonate composition of the present invention containing 6% polymaleic acid and 1% phosphoric acid. DF.TATT.F.D DESCRIPTION OF THE INVENTION The improved form of calcium carbonate prepared by the instant invention is stabilized, and thus, acid resistant, to enable its use as a filler material in the making of neutral to weakly acid paper. While not wishing to be bound by any particular theory as to the operability of the present invention, it is believed that the acid resistance conferred upon the calcium carbonate compositions of the present invention is a result of the inactivation of the surface of the calcium carbonate by the addition of the mixture of the two weak acids. In the practice of the present invention, the calcium carbonate compositions are rendered acid resistant by the inclusion of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of two or more weak acids. Especially preferred as one component of the mixture of weak acids is an organic, polymeric weak acid, such as polyacrylate or polymaleic acid.
While not wishing to be bound by any theory, it is believed that the capability of the acid-stabilized calcium carbonate of the present invention to resist dissociation in an acidic environment is due to the polymer adsorption on the surface of the calcium carbonate, absorption of polymer functional groups on the calcium carbonate surface, and the formation of a buffering system between anionic functional groups of the
polymer and a weak acid. This mechanism of polymer adsorption is distinct from absorption or reaction of the prior art sodium hexametaphosphate on the surface of calcium carbonate. Polymer adsorption can provide a barrier coating on the surface of calcium carbonate which reduces the dissolution reaction of calcium carbonate. On the other hand, the absorption or reaction of sodium hexametaphosphate is limited to the surface of the calcium carbonate. The weak acids utilized in the compositions of the present invention are preferably weak acids selected from the group consisting of phosphoric acid, metaphosphoric acid, hexa etaphosphoric acid, ethylenediaminetetraacetic acid (EDTA) , citric acid, sulfurous acid, boric acid, acetic acid, weak acids derived from organic polymeric acids, such as polyacrylate acid, polymaleic acid and polycarboxylic acid, and mixtures thereof. As noted hereinbefore, the mixture of weak acids preferably contains at least one weak acid which is derived from an organic, polymeric acid. These organic polymeric acids are typically an organic polymer having a weight average molecular weight, M„, in the range of 750-1,000,000, consisting of regularly repeating units or chemically similar units, connected by primary covalent bonds. The total amount of the weak acids utilized is at least 0.1 percent, based on the dry weight of the calcium carbonate, and is preferably about 1 to about 8 percent, based on the dry weight of the calcium carbonate.
A preferred combination of weak acids for use in the present invention is polyacrylate acid with phosphoric acid.
The calcium carbonate utilized is preferably finely divided and it can be either a precipitated calcium carbonate or a natural ground limestone.
The process for producing this acid resistant calcium carbonate involves forming a mixture of calcium carbonate with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of the mixture of weak acids. The resultant mixture is blended for a sufficiently long period of time to ensure uniform mixing of the ingredients.
The calcium carbonate can be utilized in the above- described process either as a dry powder or an aqueous slurry with up to about 60 percent by weight solids content.
The weak acids can be utilized in the process of preparation in either pure concentrated forms or as aqueous solutions. In a preferred embodiment of the instant process, either the polymeric acid or the phosphoric acid can be first added, followed by the addition of the second acid. Alternately, the polymeric acid and phosphoric acid can be added at the same time, or the polymeric acid and phosphoric acid can be mixed together and then added to the calcium carbonate.
The composition of the present invention can be utilized to.improve the optical properties of neutral to weakly acidic paper by its addition to the paper during standard manufacturing processes. Typically, the calcium carbonate composition of the present invention is added to a first paper furnish containing components necessary for making acidic paper to thereby form a second paper furnish. The invention will be further illustrated by the following Examples, which are to be considered illustrative of the invention, and not limited to the precise embodiments shown.
EXAMPLE 1
Scalenohedral Precipitated Calcium Carbonate
Stabilized with Polvacrvlate Acid and Phosphoric Acid
Acid stabilized scalenohedral precipitated calcium carbonate slurry can be obtained by the addition of a polymeric acid such as polyacrylate acid, and a weak acid such as phosphoric acid. Initially, 1%, 3%, and 6% polyacrylate acid, based on the dry weight of calcium carbonate, was added into a 19.7% solids slurry of scalenohedral precipitated calcium carbonate. The pH of the untreated scalenohedral precipitated calcium carbonate slurry was 9.05. After mixing, 1-6% phosphoric acid, based on the dry weight of calcium carbonate, was added. A plot of the pH was measured for each sample after 24-hours ageing as shown in Figure 1. A composition containing 1% polyacrylate acid, based on the dry weight of calcium carbonate, and 3% phosphoric acid, based on the dry weight of calcium carbonate was found to have an initial pH of 5.28, which rose to 5.44 after 24 hours ageing. EXAMPLE 2
Rhombic Precipitated Calcium Carbonate
Stabilized with Polvacrvlate Acid and Phosphoric Acid The initial pH of rhombic precipitated calcium carbonate was 8.29. First, 1% or 2% polyacrylate acid, based on the dry weight of calcium carbonate, was added into a 17.3% solids slurry of rhombic precipitated calcium carbonate. After blending, 1-6% phosphoric acid, based on the dry weight of calcium carbonate, was added as shown in Figure 2. The samples containing 2% polyacrylate acid have lower pHs than the 1-6% phosphoric acid and 1% polyacrylate acid, after 24 hours ageing.
EXAMPLE 3
Ground Calcium Carbonate
Stabilized with Polvacrvlate Acid and Phosphoric Acid
The initial pH of ground calcium carbonate was 8.01. Initially, 1% and 2% polyacrylate acid, based on the dry weight of calcium carbonate, was added into 20% solids slurry of ground calcium carbonate. After blending, 1-6% phosphoric acid, based on the dry weight of calcium carbonate, was added as shown graphically in Figure 3. The samples with the addition of 2% polyacrylate acid had a lower pH at the addition of 3-6% phosphoric acid compared to 1% polyacrylate acid after 24 hours ageing. EXAMPLE 4 Long Term pH Stability of Scalenohedral Precipitated Calcium Carbonate Slurry
A long-term low pH stabilized scalenohedral precipitated calcium carbonate slurry can be obtained by the combination of polyacrylate acid and phosphoric acid. The initial pH of scalenohedral precipitated calcium carbonate slurry was 9.05. At the beginning, 3% polyacrylate acid, based on the dry weight of calcium carbonate, was added to 19.8% solids scalenohedral precipitated calcium carbonate slurry, followed by the addition of 5% phosphoric acid, based on the dry weight of calcium carbonates, as shown in Figure 4. The pH of scalenohedral precipitated calcium carbonate slurry were measured and found to be 6.32 after two weeks ageing. EXAMPLE 5 Scalenohedral Precipitated Calcium Carbonate Stabilized with Polymaleic Acid and Phosphoric Acid
Acid stabilized scalenohedral precipitated calcium carbonate slurry can be obtained by the addition of a polymeric acid such as polymaleic acid, and a weak acid such as phosphoric acid. Initially, 1% polymaleic acid, based on the dry weight of calcium carbonate, was added
into 19.7% solids slurry of scalenohedral precipitated calcium carbonate. The pH of untreated scalenohedral precipitated calcium carbonate slurry was 9.05. After mixing, 4% phosphoric acid, based on the dry weight of calcium carbonate, was added. A plot of the pH was measured after 47 hours ageing as shown in Figure 5. The initial pH of the slurry was measured and found to be 5.38, which rose to 6.80 after 47 hours ageing. EXAMPLE 6 Scalenohedral Precipitated Calcium Carbonate
Stabilized with Polymaleic Acid and Phosphoric Acid
Acid stabilized scalenohedral precipitated calcium carbonate slurry can be obtained by the addition of a polymeric acid such as polymeric acid, and a weak acid such as phosphoric acid. Initially, 6% polymaleic acid, based on the dry weight of calcium carbonate, was added into 19.7% solids slurry of scalenohedral precipitated calcium carbonate. The pH of untreated scalenohedral precipitated calcium carbonate slurry was 9.05. After mixing, 1% phosphoric acid, based on the dry weight of calcium carbonate, was added. A plot of the pH was measured after 118 hours ageing as shown in Figure 6. The initial .pH of the slurry was measured and found to be 5.70. After 118 hours ageing, the pH was again measured and found to be 6.46.
Claims (13)
1. An acid resistant calcium carbonate consisting essentially of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of two or more weak acids, in admixture with the calcium carbonate.
2. The acid resistant calcium carbonate of claim 1 wherein the weak acids are selected from the group consisting of polyacrylate acid, polymaleic acid and phosphoric acid.
3. The acid resistant calcium carbonate of claim 1 wherein the mixture of weak acids includes at least one weak acid which is an organic, polymeric acid.
4. The acid resistant calcium carbonate of claim 3 wherein the mixture of weak acids is comprised of polyacrylate acid and phosphoric acid.
5. The acid resistant calcium carbonate of claim 3 wherein the mixture of weak acids is comprised of polymaleic acid and phosphoric acid.
6. The acid resistant calcium carbonate of claim 1 wherein the mixture of weak acids is present in an amount of about 1 to about 8 percent, based on the dry weight of the calcium.carbonate.
7. A process for the preparation of an acid resistant calcium carbonate which consists essentially of: a) forming a mixture of calcium carbonate with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of two or more weak acids to the mixture ; and b) blending the resultant mixture to ensure uniform mixing.
8. The process according to claim 7 wherein the weak acids of the mixture are selected from the group consisting of polyacrylate acid, polymaleic acid and phosphoric acid.
9. The process according to claim 7 wherein the mixture of weak acids includes at least one weak acid which is an organic, polymeric acid.
10. The process according to claim 7 wherein the mixture of weak acids is comprised of polyacrylate acid and phosphoric acid.
11. The process according to claim 7 wherein the mixture of weak acids is comprised of polymaleic acid and phosphoric acid.
12. The process according to claim 7 wherein the mixture of weak acids is present in an amount of about 1 to about 8 per cent, based on the dry weight of the calcium carbonate.
13. A method of improving the optical properties of neutral to weakly acidic paper by the addition of a calcium carbonate composition which consists essentially of a mixture of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of two or more weak acids, in admixture with the calcium carbonate.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54614595A | 1995-10-20 | 1995-10-20 | |
| US08/546145 | 1995-10-20 | ||
| PCT/US1996/016606 WO1997014847A1 (en) | 1995-10-20 | 1996-10-18 | Acid resistant calcium carbonate filler |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU7448496A true AU7448496A (en) | 1997-05-07 |
| AU712682B2 AU712682B2 (en) | 1999-11-11 |
Family
ID=24179073
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU74484/96A Ceased AU712682B2 (en) | 1995-10-20 | 1996-10-18 | Acid resistant calcium carbonate filler |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0859885A4 (en) |
| JP (1) | JPH11514325A (en) |
| AR (1) | AR008038A1 (en) |
| AU (1) | AU712682B2 (en) |
| BR (1) | BR9610864A (en) |
| WO (1) | WO1997014847A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2787802B1 (en) | 1998-12-24 | 2001-02-02 | Pluss Stauffer Ag | NOVEL FILLER OR PIGMENT OR MINERAL TREATED FOR PAPER, ESPECIALLY PIGMENT CONTAINING NATURAL CACO3, METHOD FOR MANUFACTURING SAME, COMPOSITIONS CONTAINING THEM, AND APPLICATIONS THEREOF |
| JPWO2004087574A1 (en) * | 2003-03-31 | 2006-06-29 | サンノプコ株式会社 | Dispersant for heavy calcium carbonate wet grinding process |
| FR2871474B1 (en) * | 2004-06-11 | 2006-09-15 | Omya Development Ag | NEW DRY MINERAL PIGMENT CONTAINING CALCIUM CARBONATE, AQUEOUS SUSPENSION CONTAINING IT AND USES THEREOF |
| FR2921568B1 (en) * | 2007-09-28 | 2014-07-25 | Coatex Sas | USE OF PHOSPHORIC ACID FOR REDUCING THE QUANTITY OF FREE DISPERSANT IN A PROCESS FOR CONCENTRATING CALCIUM CARBONATE IN WATER |
| DK2679638T3 (en) | 2012-06-28 | 2015-12-14 | Omya Int Ag | High solids aqueous mineral and / or filler and / or pigment suspension in an acidic pH environment |
| EP3045503A1 (en) | 2015-01-15 | 2016-07-20 | Omya International AG | Surface-treated calcium carbonate with improved stability in environments with a pH of 4.5 to 7 |
| JP7155127B2 (en) * | 2016-09-08 | 2022-10-18 | シェーファー・カーク・ゲーエムベーハー・ウント・コンパニー・カーゲー | Inhibitory calcium carbonate additive |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4244933A (en) * | 1978-04-05 | 1981-01-13 | Shiraishi Kogyo Kaisha, Ltd. | Calcium carbonate particles and processes for preparing same |
| JPS5540849A (en) * | 1978-09-13 | 1980-03-22 | Shiraishi Kogyo Kaisha Ltd | Internally filled paper |
| FR2642415B1 (en) * | 1989-01-27 | 1991-04-05 | Coatex Sa | PROCESS FOR GRINDING CALCIUM CARBONATE IN AQUEOUS MEDIA |
| US5156719A (en) * | 1990-03-09 | 1992-10-20 | Pfizer Inc. | Acid-stabilized calcium carbonate, process for its production and method for its use in the manufacture of acidic paper |
| JP3254021B2 (en) * | 1992-12-14 | 2002-02-04 | 三菱化学株式会社 | Polyolefin resin composition with improved hue |
-
1996
- 1996-10-18 WO PCT/US1996/016606 patent/WO1997014847A1/en not_active Application Discontinuation
- 1996-10-18 JP JP9515975A patent/JPH11514325A/en active Pending
- 1996-10-18 BR BR9610864A patent/BR9610864A/en not_active Application Discontinuation
- 1996-10-18 AU AU74484/96A patent/AU712682B2/en not_active Ceased
- 1996-10-18 EP EP96936596A patent/EP0859885A4/en not_active Ceased
- 1996-10-21 AR ARP960104836A patent/AR008038A1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| EP0859885A1 (en) | 1998-08-26 |
| AR008038A1 (en) | 1999-12-09 |
| EP0859885A4 (en) | 1999-06-09 |
| JPH11514325A (en) | 1999-12-07 |
| BR9610864A (en) | 1999-04-06 |
| AU712682B2 (en) | 1999-11-11 |
| WO1997014847A1 (en) | 1997-04-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |