EP0277728A2 - Drainage and retention aids for newsprint furnishes - Google Patents
Drainage and retention aids for newsprint furnishes Download PDFInfo
- Publication number
- EP0277728A2 EP0277728A2 EP88300477A EP88300477A EP0277728A2 EP 0277728 A2 EP0277728 A2 EP 0277728A2 EP 88300477 A EP88300477 A EP 88300477A EP 88300477 A EP88300477 A EP 88300477A EP 0277728 A2 EP0277728 A2 EP 0277728A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- paper
- polymer
- weight
- acrylamide
- retention
- 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.)
- Withdrawn
Links
Classifications
-
- 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
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
-
- 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
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
- D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
- D21H17/45—Nitrogen-containing groups
- D21H17/455—Nitrogen-containing groups comprising tertiary amine or being at least partially quaternised
Abstract
Description
- This invention relates to the use of acrylamide/acryloyloxyethyl trimethyl ammonium chloride polymers as drainage/retention aids in the manufacture of paper and paper-like products.
- In papermaking, retention is generally defined as the retaining of inorganic fillers, such as clay and titanium dioxide, as well as cellulosic fines within the paper sheet during manufacture, as on a fourdrinier machine. The retention obtained on the wire screen is a function of different mechanisms such as filtration by mechanical entrainment, electrostatic attraction, and bridging between cellulosic fibers and fillers. Since both the cellulose and many common fillers are electronegative, they are mutually repellant and, in the absence of a retention aid, the only factor tending to enhance retention is mechanical entrainment.
- Generally, retention aids are used because of the high cost of pigments, such as titanium dioxide. The use of retention aids significantly increases the amount of pigments incorporated into a wet web. Additionally, retention aids can appreciably reduce the suspended material in a paper machine white water effluent stream, which reduces pollution and loss of pigment.
- Retention aids are commonly used in the manufacture of specialty papers, such as bond paper and "publication type" paper, including newsprint, where high loadings of pigment and/or filler are required. The function of retention aids is to bind a filler to cellulosic fibers without mechanically blocking the pores of the paper sheet being formed, thereby not adversely affecting the drainage properties of the wet paper web. Drainage, as used herein, refers to dewatering of paper or paper-like products being formed, as on a fourdrinier machine. The instant polymers improve both the retention and drainage properties of paper furnishes, and are therefore referred to as drainage/retention aids.
- The prior art discloses the use of polyacrylamides as retention aids wherein about 3 to 35% of the amide groups are hydrolyzed to carboxylic acid groups. It is essential for alum to be present for such retention aids to work effectively, and their use is generally restricted to narrow pH ranges.
- Amphoteric polymers have also been used as retention aids. For example, see U.S. Patent 3,639,208, which discloses the use of hydrolyzed acrylamide diallyl quaternary ammonium polymers as retention aids. U.S. Patent 3,926,718 discloses the use of N-vinylpyrrolidone/water soluble monomer block-type polymers as retention aids, wherein suitable water-soluble monomers include dimethyl diallyl ammonium chloride, 3-acrylamido-3-methylbutyl trimethyl ammonium chloride, methacryloyloxy 2-hydroxypropyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium methosulfate, 2-acrylamido-2-methylpropane sulfonic acid, acrylic acid and salts thereof, methacrylic acid, 3-acrylamido-3-methylbutyl dimethylamine, acrylamide, methacrylamide, diacetone acrylamide, hydroxymethylated diacetone acrylamide, dimethyl-1-(2-hydroxypropyl) amine methacrylamide, and sodium styrene sulfonate.
- U.S. Patent 4,147,681 discloses the use of acrylamide homopolymer and copolymer emulsions as drainage/retention aids.
- With respect to retention, newsprint furnishes present a difficult situation because of contaminants and carry-over from pulping operations. Because of these impurities, conventional drainage/retention aids become inactivated due to the demand of the contaminants for polymers. U.S. Patent 4,070,236 discloses the use of phenyl-naphtanol-sulfur resins in conjunction with polyalkylene oxides as newsprint retention aids.
- The instant invention provides an improvement in the art of papermaking in which the retention of cellulosic fines, fillers, pigments and other chemical additives is increased by the use of acrylamide (AM)/acrylolyoxyethyl trimethyl ammonium chloride (AETAC) polymers. These polymers, which contain from about 75% to about 99.9% acrylamide and from about 0.1% to about 25% AETAC, by weight, and which also improve drainage properties, are especially effective in newsprint furnishes.
- This invention relates to a method for improving drainage and the retention of inorganic fillers, cellulosic fines, chemical additives and/or pigments in the production of paper comprising adding to an aqueous paper furnish an effective amount of a polymer comprising:
- (a) acrylamide or methacrylamide, preferably acrylamide; and
- (b) a monomer of the following structure:
- The instant invention additionally relates to the above described polymers, and to compositions comprising (a) a paper or paper-like furnish, preferably a newsprint furnish, and (b) at least one of the above described polymers.
- As used herein, the term "effective amount" refers to that amount of polymer which provides a drainage and/or retention improving quality to the furnish being treated. Generally, the polymer dosage, on an active basis, ranges from about 0.1 to about 10 pounds of polymer per dry ton of pulp.
- While the instant polymers may be used as drainage/retention aids in any paper furnish, including furnish for fine paper, bond paper and publication-type paper, and in furnishes for the preparation of miscellaneous paper-like products such as liner board, they are especially effective in newsprint furnishes. As used herein, the term "newsprint furnishes" is defined as a furnish which is used to prepare newsprint paper, such as a furnish containing groundwood, mechanical pulp, Kraft pulp, Kraft sulfite pulp, semi-bleached Kraft pulp, thermal-mechanical pulp, deink stock and/or recycled paper.
- The instant polymers may be added to a paper furnish at any convenient point to improve drainage and/or the retention of fines, fibers and additives on the paper web being treated. Generally, however, the drainage/retention aid will be added at a point immediately prior to the forming surface.
- It is a particular feature of this invention that the introduction of the instant polymers into a papermaking furnish, particularly a newsprint furnish, will lead to improved drainage and/or improved retention of the cellulosic fines and various additives, including but not limited to pigment and fillers, over a wide range of pH and other chemical conditions. The desired drainage and retention improving characteristics of the instant polymers have been demonstrated in a wide variety of furnishes, as demonstrated by the examples included herein.
- The polymers of the instant invention may be described by the following structure:
- Generally, about 0.5 pounds of the instant polymer (active basis) per ton of dry pulp will be used. The instant drainage/retention aids will seldom be used in amounts of less than 0.1 pound per ton of dry pulp, and in normal practice, for economic reasons, they will not be used in amounts higher than about 2 pounds per ton of dry pulp, although in some cases more drainage/retention aid may be used without adverse effect, for instance, 5 or even 10 pounds per ton of dry pulp.
- The instant polymers may be applied in any convenient form, e.g., as aqueous solutions, or emulsions, and they may be prepared by emulsion and solution polymerization techniques which are well known to those skilled in the art.
- For example, an aqueous phase containing acrylamide and AETAC monomers may be prepared. These monomers are water-soluble. A water-in-oil emulsion of this aqueous phase may then be prepared by dispersing the aqueous phase into a hydrophobic liquid, using a suitable emulsifying surfactant. Inert hydrophobic liquids which can be used as the hydrophobic phase include, but are not limited to, mineral oils, kerosene, naphthas, petroleums and blends of aromatic and aliphatic hydrocarbons. Polymerization is then initiated using a free radical initiator, such as teritary butyl hydroperoxide. Polymerization may then proceed either adiabetically or isothermally. See, for example, USSN 757,966, which is incorporated by reference into this document, and which describes a method for manufacturing stable water-in-oil emulsions of water soluble polymers using an oil soluble alkanolamide-based surfactant system. Also, see U.S. Patent 1,147,681, which discloses a method for preparing acrylamide-type emulsion polymers.
- The following examples further demonstrate the instant invention. They are not intended to limit the scope of the instant invention in any way.
- Emulsion polymers of acrylamide and acryloyloxyethyl trimethyl ammonium chloride (AETAC) were prepared by the conventional emulsion polymerization technique described below:
- An aqueous phase comprising: a) acrylamide and AETAC in the desired weight ratio; b) water; and c) sodium ethylendiamine tetracetic acid was mixed. The pH of this phase was adjusted to 3.0.
- Separately, an oil-soluble alkanolanide-based surfactant system was added to the oil phase. Any conventional emulsifying surfactants can be used. The aqueous phase was then dispersed into the oil/surfactant phase, and polymerization was initiated using a tertiary butyl hydroperoxide/sodium metabisulfate catalyst system under nitrogen. Polymerization continued either adiabatically or isothermally to completion.
- Reduced viscosities of the resulting polymers were measured at 0.05 g/l using a 1.0 N sodium chloride solution at 30°C.
- For 90/10 acrylamide/AETAC polymers, the aqueous phase comprised:
748.99 g of 45.6% active acrylamide;
50.60 g of 75% active AETAC;
262.26 g of water; and
1.50 g of Na₄ EDTA chelant. - For 97/3 acrylamide/AETAC polymers, the aqueous phase comprised:
828.54 g of 45.6% active acrylamide;
15.17 g of 75% active AETAC;
238.14 g of water; and
1.5 g of Na₄ EDTA chelant. - The oil phase comprised 349.00 g of Kensol 61, a branch-chain hydrocarbon commercially available from Witco Chemical Company, in both the 90/10 and 97/3 cases.
- The alkanolamide-based emulsifying surfactant system was added to the oil phase in sufficient amount to uniformly disperse the aqueous phase into the oil phase. All polymers used in Examples 2-20 were prepared in accordance with these instructions.
-
- To measure retention efficacy, first pass fines retention values were determined using standard Britt Jar Tests. The Britt Jar Tests were run by establishing a mixing speed which gave approximately the same % retention as was obtained on the corresponding paper machine (using untreated headbox stock). The following procedures were followed:
- 1. The Britt Jar mixing speed was set at the established rate.
- 2. 500 mls of untreated headbox stock were poured into the jar and mixed for 30 seconds.
- 3. The pinch clamp was opened and 100 mls of filtrate was collected in a graduated cylinder.
- 4. The contents of Step 3 were filtered through pre-weighed filter paper, and then collected fines were completely dried. % fines retention was then calculated, which served as the untreated (comparison example) % retention value for each furnish.
- 5. Retention aids were evaluated by adding the desired amount of polymer to the furnish being tested and mixing. Step 4 was then repeated.
-
- The effectiveness of the instant polymers as drainage aids was evaluated using a standard Schopper-Riegler Freeness Tester. Standard laboratory procedures were employed.
- An unbleached Kraft/waste furnish corrugating media served as the test furnish. This furnish had a % consistency of 1.28, a pH of 7.5 and a stock temperature of 120°F. The polymer dosage was 4.0 lbs/ton of dry pulp.
-
Claims (10)
(i) 75 to 99.9%, by weight, acrylamide or methacrylamide, and
(ii) 25 to 0.1%, by weight, a monomer of the following structure:
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US898187A | 1987-01-30 | 1987-01-30 | |
US8981 | 1995-12-21 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0277728A2 true EP0277728A2 (en) | 1988-08-10 |
EP0277728A3 EP0277728A3 (en) | 1988-08-17 |
Family
ID=21734842
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP88300477A Withdrawn EP0277728A3 (en) | 1987-01-30 | 1988-01-21 | Drainage and retention aids for newsprint furnishes |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0277728A3 (en) |
AU (1) | AU1093388A (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4022651A1 (en) * | 1990-07-17 | 1992-01-23 | Muenzing Chemie Gmbh | Cationic water-soluble or water-dispersible homo- or copolymers - prepd. from quat. ammonium acrylate- or acrylamide-based monomer and used as dispersing or grinding aid for pigments or fillers |
WO1992020862A1 (en) * | 1991-05-17 | 1992-11-26 | Delta Chemicals, Inc. | Production of paper and paper products |
US5194120A (en) * | 1991-05-17 | 1993-03-16 | Delta Chemicals | Production of paper and paper products |
US6007679A (en) * | 1996-05-01 | 1999-12-28 | Nalco Chemical Company | Papermaking process |
US6238521B1 (en) | 1996-05-01 | 2001-05-29 | Nalco Chemical Company | Use of diallyldimethylammonium chloride acrylamide dispersion copolymer in a papermaking process |
WO2004052942A1 (en) * | 2002-12-06 | 2004-06-24 | Hercules Incorporated | Cationic or amphoteric copolymers prepared in an inverse emulsion matrix and their use in preparing cellulosic fiber compositions |
US7250448B2 (en) | 2001-12-07 | 2007-07-31 | Hercules Incorporated | Anionic copolymers prepared in an inverse emulsion matrix and their use in preparing cellulosic fiber compositions |
CN101215800B (en) * | 2008-01-04 | 2010-06-09 | 广州造纸股份有限公司 | Method for producing low-dosing newsprint paper by using unitary retention and filter aid |
WO2015123094A1 (en) * | 2014-02-11 | 2015-08-20 | 3M Innovative Properties Company | Filler compound comprising a positively charged polymer |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2838397A (en) * | 1956-04-10 | 1958-06-10 | Rohm & Haas | Process for the preparation of mineralfilled papers |
US3239496A (en) * | 1962-09-24 | 1966-03-08 | Nalco Chemical Co | Method for producing polymeric salts of aminoalkylacrylates |
GB1195737A (en) * | 1967-01-25 | 1970-06-24 | Nalco Chemical Co | Process for Increasing Drainage from an Aqueous Suspension of Cellulosic Fibers |
US3901857A (en) * | 1972-11-11 | 1975-08-26 | Bayer Ag | Process for the production of high molecular weight cationic acrylamide copolymers |
US4461866A (en) * | 1982-05-24 | 1984-07-24 | Sun Chemical Corporation | Preparation of water-in-oil emulsions |
US4581402A (en) * | 1981-06-12 | 1986-04-08 | Societe Francaise Hoechst | Novel stable water in oil dispersions of hydrosoluble cationic polymers based on salified or quaternized dimethylaminoethyl acrylate, process of preparation thereof and application thereof as flocculents |
-
1988
- 1988-01-21 EP EP88300477A patent/EP0277728A3/en not_active Withdrawn
- 1988-01-28 AU AU10933/88A patent/AU1093388A/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2838397A (en) * | 1956-04-10 | 1958-06-10 | Rohm & Haas | Process for the preparation of mineralfilled papers |
US3239496A (en) * | 1962-09-24 | 1966-03-08 | Nalco Chemical Co | Method for producing polymeric salts of aminoalkylacrylates |
GB1195737A (en) * | 1967-01-25 | 1970-06-24 | Nalco Chemical Co | Process for Increasing Drainage from an Aqueous Suspension of Cellulosic Fibers |
US3901857A (en) * | 1972-11-11 | 1975-08-26 | Bayer Ag | Process for the production of high molecular weight cationic acrylamide copolymers |
US4581402A (en) * | 1981-06-12 | 1986-04-08 | Societe Francaise Hoechst | Novel stable water in oil dispersions of hydrosoluble cationic polymers based on salified or quaternized dimethylaminoethyl acrylate, process of preparation thereof and application thereof as flocculents |
US4461866A (en) * | 1982-05-24 | 1984-07-24 | Sun Chemical Corporation | Preparation of water-in-oil emulsions |
Non-Patent Citations (3)
Title |
---|
ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, Vol. 48, No. 5, November 1977, Page 527, Abstract No. 4846; K. SUZUKI et al.: "Preparation of cationic polymers and their applications. (6). Effect of partially aminated polyacrylamides on paper strength improvement for various pulps (especially for newsprint paper pulp)"; & JAPAN TAPPI 31, No. 5: Pages 270-274 (May 1977) * |
ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, Vol. 51, No. 10, April 1981, Page 1111, Abstract No. 10392, Appleton, Wisconsin, US; T. MIWA et al.: "Improvement of filler efficiency in manufacturing paper". * |
TAPPI JOURNAL, Vol. 66, No. 6, June 1983, Pages 83-85, Atlanta, Georgia, US; T. LINDSTRÖM et al.: "Effects of pH and electrolyte concentration on the adsorption of cationic polyacrylamides on cellulose". * |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4022651A1 (en) * | 1990-07-17 | 1992-01-23 | Muenzing Chemie Gmbh | Cationic water-soluble or water-dispersible homo- or copolymers - prepd. from quat. ammonium acrylate- or acrylamide-based monomer and used as dispersing or grinding aid for pigments or fillers |
WO1992020862A1 (en) * | 1991-05-17 | 1992-11-26 | Delta Chemicals, Inc. | Production of paper and paper products |
US5194120A (en) * | 1991-05-17 | 1993-03-16 | Delta Chemicals | Production of paper and paper products |
AU650404B2 (en) * | 1991-05-17 | 1994-06-16 | Delta Chemicals, Inc. | Production of paper and paper products |
US6007679A (en) * | 1996-05-01 | 1999-12-28 | Nalco Chemical Company | Papermaking process |
US6238521B1 (en) | 1996-05-01 | 2001-05-29 | Nalco Chemical Company | Use of diallyldimethylammonium chloride acrylamide dispersion copolymer in a papermaking process |
US7250448B2 (en) | 2001-12-07 | 2007-07-31 | Hercules Incorporated | Anionic copolymers prepared in an inverse emulsion matrix and their use in preparing cellulosic fiber compositions |
WO2004052942A1 (en) * | 2002-12-06 | 2004-06-24 | Hercules Incorporated | Cationic or amphoteric copolymers prepared in an inverse emulsion matrix and their use in preparing cellulosic fiber compositions |
US7396874B2 (en) | 2002-12-06 | 2008-07-08 | Hercules Incorporated | Cationic or amphoteric copolymers prepared in an inverse emulsion matrix and their use in preparing cellulosic fiber compositions |
CN101215800B (en) * | 2008-01-04 | 2010-06-09 | 广州造纸股份有限公司 | Method for producing low-dosing newsprint paper by using unitary retention and filter aid |
WO2015123094A1 (en) * | 2014-02-11 | 2015-08-20 | 3M Innovative Properties Company | Filler compound comprising a positively charged polymer |
US9809696B2 (en) | 2014-02-11 | 2017-11-07 | 3M Innovative Properties Company | Filler compound comprising a positively charged polymer |
Also Published As
Publication number | Publication date |
---|---|
EP0277728A3 (en) | 1988-08-17 |
AU1093388A (en) | 1988-08-04 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0017353B1 (en) | Production of paper and paper board | |
US4894119A (en) | Retention and/or drainage and/or dewatering aid | |
EP1451234B1 (en) | Composition comprising cellulose fiber and a water-soluble anionic copolymer as well as method of making said composition | |
US4749444A (en) | Production of paper and cardboard | |
US6048438A (en) | Method to enhance the performance of polymers and copolymers of acrylamide as flocculants and retention aids | |
US5989392A (en) | Method of using polyammonium quaternary for controlling anionic trash and pitch deposition in pulp containing broke | |
US5798023A (en) | Combination of talc-bentonite for deposition control in papermaking processes | |
US5262008A (en) | Production of paper, board and cardboard in the presence of copolymers containing N-vinylformamide units | |
US5902455A (en) | Process for improving retention in a process for the manufacture of paper, board and the like, and retaining agent for the application of this process | |
US5567277A (en) | Cellulosic, modified lignin and cationic polymer composition and process for making improved paper or paperboard | |
AU2002352927A1 (en) | High molecular weight cationic and anionic polymers comprising zwitterionic monomers | |
EP0000922B1 (en) | A process for preparing a non-woven fibrous web from fibers and a latex, and the non-woven fibrous material so prepared | |
EP0277728A2 (en) | Drainage and retention aids for newsprint furnishes | |
EP0877120B1 (en) | Papermaking process | |
US5647956A (en) | Cellulosic, modified lignin and cationic polymer composition and process for making improved paper or paperboard | |
EP0058621A1 (en) | Reducing the deposition of pitch-like resins in the production of paper | |
US5532308A (en) | Method for improving retention and drainage characteristics in alkaline papermaking | |
US4515658A (en) | Retention aids | |
US5393380A (en) | Polydiallyl dimethyl ammonium chloride/3-acrylamido-3-methylbutanoic acid copolymers and their use for pitch control in paper mill systems | |
US5501773A (en) | Cellulosic, modified lignin and cationic polymer composition and process for making improved paper or paperboard | |
EP1082493B1 (en) | Papermaking process utilizing hydrophilic dispersion polymers of diallyldimethyl ammonium chloride and acrylamide as retention and drainage aids | |
JPH07506151A (en) | Paper and paperboard manufacturing | |
EP0628658A1 (en) | Cellulosic, modified lignin and cationic polymer composition and process for making improved paper or paperboard | |
WO2003050354A1 (en) | Use of hydrophillic polymer dispersion containing a colloidal silica or an inorganic flocculant as retention and drainage aids in paper making process | |
EP0119493A1 (en) | Use of copolymers of 2-acrylamido-2-methylpropane sulfonic acid for improving retention and dewatering in the manufacture of paper |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): BE CH DE FR GB LI SE |
|
AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): BE CH DE FR GB LI SE |
|
ITCL | It: translation for ep claims filed |
Representative=s name: SOCIETA' ITALIANA BREVETTI S.P.A. |
|
17P | Request for examination filed |
Effective date: 19890109 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
|
18W | Application withdrawn |
Withdrawal date: 19891228 |
|
R18W | Application withdrawn (corrected) |
Effective date: 19891228 |