WO2002050344A1 - Decapage et decalaminage par voie electrolytique continue de l'acier au carbone et de l'acier inoxydable - Google Patents

Decapage et decalaminage par voie electrolytique continue de l'acier au carbone et de l'acier inoxydable Download PDF

Info

Publication number
WO2002050344A1
WO2002050344A1 PCT/IT2001/000637 IT0100637W WO0250344A1 WO 2002050344 A1 WO2002050344 A1 WO 2002050344A1 IT 0100637 W IT0100637 W IT 0100637W WO 0250344 A1 WO0250344 A1 WO 0250344A1
Authority
WO
WIPO (PCT)
Prior art keywords
current
anodic
descaling
electrolytic
pickling
Prior art date
Application number
PCT/IT2001/000637
Other languages
English (en)
Inventor
Susanna Ramundo
Alessandro Dulcetti
Original Assignee
Centro Sviluppo Materiali S.P.A.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from IT2000RM000674 external-priority patent/IT1316027B1/it
Priority claimed from IT2000RM000675 external-priority patent/IT1316028B1/it
Application filed by Centro Sviluppo Materiali S.P.A. filed Critical Centro Sviluppo Materiali S.P.A.
Priority to KR10-2003-7008160A priority Critical patent/KR20030076589A/ko
Priority to AT01271468T priority patent/ATE276386T1/de
Priority to EP01271468A priority patent/EP1358367B1/fr
Priority to AU2002217449A priority patent/AU2002217449A1/en
Priority to DE60105653T priority patent/DE60105653T2/de
Publication of WO2002050344A1 publication Critical patent/WO2002050344A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
    • C25F1/02—Pickling; Descaling
    • C25F1/04—Pickling; Descaling in solution
    • C25F1/06—Iron or steel

Definitions

  • the present invention refers to the continuous pickling of hot-rolled carbon steels strips by an electrolytic process in a neutral solution (pH ranging from 6.0 to 8.0).
  • the present invention further refers to the field of the continuous descaling of stainless steels strip for the removal of surface oxides formed by effect of thermal
  • the advantages of the neutral electrolytic pickling and descaling processes with respect to the conventional processes in acid baths are substantially the following: adoption of non-dangerous, non-harmful and non-polluting pickling baths; easy treating and reclaiming of the residues; and elevated surface quality of the pickled
  • the first reaction (0) is merely viable at a low electrode potential and it is marginal as a pickling reaction; it becomes virtually negligible for current density (I) values exceeding a predetermined threshold value (I 0 ).
  • reaction (1) acidifies the metal-scale interface
  • reaction (2) changes the scale into a soluble compound, by virtue of the presence of the acidified interface.
  • the anodic oxidation of the underlying metal begins to rise until reaching its equilibrium rate at the passive state, when all the scale has been removed from the surface (end of the pickling treatment). Therefore, under the electrolytic pickling mechanism defined by the second (1) and by the third (2) reaction the fourth reaction
  • auxiliary electrodes also called counterelectrodes
  • the abovereported anodic reactions take place under diffusion control.
  • the reaction ratios depend on the diffusion of the reactants and of the reaction products through the boundary layer (flow), which in turn is determined by the fluid dynamics onto the steel surface.
  • the increase in the burble of the solution at the interface can cause contrasting effects onto the attack rate of the scale, as it also increases the flow of Hydrogen ions (H + ) which leaves the interface acidified [reaction (1)].
  • the function of the descaling is that of modifying the scale in order to facilitate the subsequent removal thereof.
  • the scale conditioning methods for hot-rolled stainless steel strips mainly use molten salt baths (thermochemical descaling) or electrolytic treatments.
  • thermochemical process currently used for descaling provides the immersion in an oxidising molten salt bath which is capable of converting the Chromium oxides (or the mixed Chromium/Iron oxides) into soluble hexavalent Chromium compounds.
  • Electrolytic descaling is a common industrial process which can be carried out in acid electrolytes as well as in neutral electrolytes, the anion usually being the sulfate ion. Particularly attractive is the process of electrolytic descaling in a neutral solution. In fact, this type of descaling is effective in dissolving the scale and the removed scale is directly separated from the solution by precipitation, with no need of a residue treatment (e.g., by neutralizing). Moreover, for the construction of the plant no material particularly resistant to corrosion is required.
  • the main anodic reactions of oxide scale change leading to the electrolytic descaling in a neutral solution can be schematized as follows: H 2 O ⁇ 2H + + > / 2 0 2 + 2e " (4)
  • auxiliary electrodes or counterelectrodes
  • the cathodic reactions enabling the electrical neutrality of the solution to be preserved develop.
  • reaction (4) merely applies to austenitic stainless steels, as ferritic stainless steels do not contain appreciable quantities of Nickel as an alloy metal. As a side effect of the dissolving of the Iron and Nickel oxides, a larger quantity of Cr 2 0 becomes available for the anodic change.
  • the resulting electrolytic descaling mechanism in a neutral solution involves the anodic oxidation of the Chromium and the interface acidification, which determines the dissolving of the Iron oxide, and, when present, of the Nickel oxide.
  • the quantity of a substance obtained (changed) at the electrodes is proportional to the quantity of electric charge passed through the electrolytic circuit. More particularly, the quantity of electric charge required to obtain (change) a given quantity of substance is constant (e.g., for one equivalent of any substance one Faraday, i.e. 96.500 Coulomb, is required). Hence, for the electrolytic change of a given quantity of substance, the associated current density is constant.
  • - I is the current density crossing the cell
  • - k is a time constant for the calculation of the fraction of electric charge density, proportional to the current density I (kl), outputted for the indirect anodic reactions linked to Oxygen development and to the consequent acidification at the steel/electrolytic solution interface, for the Carbon steels, and at the scale/solution interface, for the stainless steels.
  • the neutral saline solution preferably consists of sodium sulfate, in a concentration from 0,5 to 2,5 M, at a temperature ranging from 30 to 100°C.
  • the minimum quantity of electric charge c ranges from 200 to 1250 C/dm 2 (Carbon steels) and from 40 to 200 C/dm 2 (stainless steels) and the time constant k ranges from 2 s to 25 s, preferably from 2 to 11 s for Carbon steels and from 2 to 25 s for stainless steels.
  • Treatment times range from 7 to 50 s for Carbon steels and from 2 to 45 s for stainless steels.
  • Current density ranges from 10 to 80 A/dm 2 (Carbon steels) and from 5 to 150 A/dm 2 (stainless steels).
  • the conditions governing the neutral electrolytic process should also be observed in the design of the related pickling lines, which should ensure the functionality of the process at various flow rates of the strip to be processed.
  • the anodic treatment time depends on the line speed (v) and on the total length of the electrodes (L) which give the anodic polarization to the strip to be processed. Therefore, the preceding equation describing the quantity of electric charge outputted during the electrolytic process in a neutral solution may be rewritten as follows
  • Another object of the present invention is the use of the abovedescribed electrolytic method, characterised in that, setting the width and the flow rate of the strip, the total anodic electrode length, and therefore the length of the related continuous neutral electrolytic treatment line, the current to be outputted, selected according to the abovedescribed method, is defined.
  • the electrolytic treatment of steel strips is usually carried out in cells consisting of a set of electrodes connected to opposite poles of the power supplies, which determine alternatively anodic and cathodic polarization sequences onto the strip to be descaled.
  • the descaling process merely requires the anodic polarization
  • the addition of the cathodic stage entails the advantage of having the electrochemical reactions take place directly onto the strip, with no direct connection of the latter to the power supplies; thus, the employ of costly cunent carrier rolls can be avoided. Therefore, the total length (L) of the electrodes imposing the anodic polarization onto the strip is given by the sum of the unitary lengths (L a ) of the individual electrode units.
  • the cell may have a vertical or a horizontal development, according to plant convenience criteria.
  • the neutral electrolytic treatment equation disclosed in the present invention shows that there is an electrolysis time (k) which is inactive for the treatment.
  • k an electrolysis time which is inactive for the treatment.
  • the frequency (f) of each anodic current pulse should be where the factor Vi is introduced in order to take into account the total treatment time
  • This frequency limit value for the electrolytic pickling in a neutral solution is compatible with the reaction mechanisms advanced for the treatment, implying the acidification of the electrified interface in order to foster the dissolving of the oxides.
  • Adopting e.g., hot-rolled Carbon steels strips under predetemined industrial conditions (with constant post-rolling cooling modes)
  • the scale obtained exhibits a near-constant composition and morphology, requiring in order to be electrolytically pickled a minimum charge quantity c, depending on the pre-pickling scale-breaking mechanical treatment.
  • the electrolytic method in a neutral solution according to the present invention may also be carried out by AC current having a frequency lower than 3 Hz, with total treatment times and applied currents selected, for suitable values of c' and k', according to the formula:
  • Fig. 1 shows patterns of the descaling, as scale fraction P(t)/P ⁇ changed as a function of time, for initial scales P ⁇ l and P ⁇ 2 > P ⁇ .
  • the patterns were obtained integrating a descaling equation obtained in light of the experimental observation of the loss of mass during the descaling process.
  • Example 1
  • a common low-Carbon steel having hot-rolling scale mechanically pre-conditioned by roll-induced squashing (about 2.5% lengthening) is subjected to the continuous electrolytic pickling method in a neutral solution according to the present invention.
  • c 490 C/dm 2 and k is equal to 3.7 s.
  • the total anodic electrode length (L), and therefore the length of the pickling plant are set with regard to the current applied in the cell according to the provisions of the equation of the neutral electrolytic pickling according to the present invention.
  • the current density (I) to be applied to the electrolytic pickling cell as a function of the anodic electrode length (L) and of the varying of the line speed (v) is reported in column 3 of Table 1 ; in column 4 the electric charge density (Q), and in column 5 the total current (I tot ) to be outputted, calculated multiplying the current density for the anodic electrode surface, are indicated.
  • the electric charge density (Q) to be outputted for the electrolytic pickling increases when the anodic electrode length decreases.
  • the total current (I tot ) applied increases.
  • the slow-speed (20 m/min) operation implies the employ of a total anodic length not exceeding 16 m, lest the condition that I>I 0 be not met. This is attained by sectioning the electrodes and power- supplying only a section thereof, regardless of the total length of the anodes installed in the cells.
  • Example 2
  • the total anodic electrode length (L), and therefore the length of the pickling plant are set with regard to the current applied in the cell, according to the provisions of the equation of continuous neutral electrolytic pickling according to the invention.
  • Table 3 the current densities (I) to be applied to the electrolytic pickling cell as a function of the anodic electrode length (L) and of the line speed (v) are shown. In Table 3 also all the other related quantities are reported.
  • the descaling plant consists of 12 cells, each one having an unitary anode length L a
  • the former should be capable of operating at a speed ranging from 40 to 120 m min, according to two different process control logics: in the one case (see Table 4a) with the logic of maximising the use of the power from the individual power supplies (i.e., use of a number of cells proportional to the line speed) and, in the other case (see Table 4b), with the constant employ of all the cells (i.e., use of a current density proportional to the line speed).
  • Table 4a with the logic of maximising the use of the power from the individual power supplies (i.e., use of a number of cells proportional to the line speed) and, in the other case (see Table 4b), with the constant employ of all the cells (i.e., use of a current density proportional to the line speed).
  • the direct current density (I) to be applied to the electrolytic pickling cell at the variation of the line speed (v) is reported in column 2 of Table 5; in column 3 the electric charge density (Q), and in column 4 the total current (I tot ) to be outputted, calculated multiplying the current density for the anodic electrode surface, are indicated.
  • the operative parameters of this plant, calculated with the descaling equation according to the invention, are reported in Table 6.
  • the operative parameters of this plant, calculated by the descaling equation according to the invention are reported in Table 7.
  • the two process control logics are not equivalent, as overall lesser total descaling currents are required when operation is carried out maximising the number of cells employed. In this case as well, the underrating of the descaling current by the classical equation of electrolysis persists.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

La présente concerne un procédé d'électrolyse continue en solution neutre destiné au décapage et au décalaminage des aciers au carbone et des aciers inoxydables, en présence des effets indirects du passage du courant d'électrolyse, ledit courant étant un courant alternatif ou continu ayant une fréquence inférieure à 3 Hz, caractérisé en ce que les temps de traitement anodiques et les courants de cellules sont sélectionnés selon la formule It=c + kI, dans laquelle I représente la densité du courant traversant la cellule, t représente le temps de traitement anodique, c représente la fraction de constante de la densité de la charge électrique produite pour les réactions anodiques directes de transformation des oxydes et k représente une constante de temps destinée au calcul de la fraction de la densité de la charge électrique proportionnelle à la densité du courant I (kI), produite pour les réactions anodiques indirectes liées au développement de l'oxygène et à l'acidification conséquente au niveau de l'interface acier/solution électrolytique (aciers au carbone) ou au niveau de l'interface couche d'oxyde/solution électrolytique (aciers inoxydables).
PCT/IT2001/000637 2000-12-18 2001-12-18 Decapage et decalaminage par voie electrolytique continue de l'acier au carbone et de l'acier inoxydable WO2002050344A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
KR10-2003-7008160A KR20030076589A (ko) 2000-12-18 2001-12-18 탄소강 및 스테인레스강의 연속적인 전해 산세척 및디스케일링 방법
AT01271468T ATE276386T1 (de) 2000-12-18 2001-12-18 Kontinuierliches elektrolytisches beizen und entzundern von unlegiertem stahl und nichtrostendem stahl
EP01271468A EP1358367B1 (fr) 2000-12-18 2001-12-18 Decapage et decalaminage par voie electrolytique continue de l'acier au carbone et de l'acier inoxydable
AU2002217449A AU2002217449A1 (en) 2000-12-18 2001-12-18 Continuous electrolytic pickling and descaling of carbon steel and stainless
DE60105653T DE60105653T2 (de) 2000-12-18 2001-12-18 Kontinuierliches elektrolytisches beizen und entzundern von unlegiertem stahl und nichtrostendem stahl

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
ITRM2000A000674 2000-12-18
IT2000RM000674 IT1316027B1 (it) 2000-12-18 2000-12-18 Metodo per il decapaggio elettrolitico continuo in soluzione neutra di acciaio al carbonio in presenza di effetti indiretti del passaggio di
IT2000RM000675 IT1316028B1 (it) 2000-12-18 2000-12-18 Metodo per la descagliatura elettrolitica continua in soluzione neutra di acciai inossidabili in presenza di effetti indiretti del passaggio
ITRM2000A000675 2000-12-18

Publications (1)

Publication Number Publication Date
WO2002050344A1 true WO2002050344A1 (fr) 2002-06-27

Family

ID=26332841

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IT2001/000637 WO2002050344A1 (fr) 2000-12-18 2001-12-18 Decapage et decalaminage par voie electrolytique continue de l'acier au carbone et de l'acier inoxydable

Country Status (8)

Country Link
EP (1) EP1358367B1 (fr)
KR (1) KR20030076589A (fr)
CN (1) CN1231615C (fr)
AT (1) ATE276386T1 (fr)
AU (1) AU2002217449A1 (fr)
DE (1) DE60105653T2 (fr)
ES (1) ES2232564T3 (fr)
WO (1) WO2002050344A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002086199A2 (fr) * 2001-04-24 2002-10-31 Centro Sviluppo Materiali S.P.A. Procede electrolytique continu realise dans une solution acide pour decalaminer des aciers inoxydables, en presence d'effets indirects d'un flux de courant
WO2011039596A1 (fr) 2009-09-30 2011-04-07 Tenova S.P.A. Unité de préparation de surfaces pour lignes de transformation de bandes métalliques
CN104120438A (zh) * 2014-07-22 2014-10-29 中冶南方工程技术有限公司 一种热轧304奥氏体不锈钢带钢酸洗生产方法
WO2021105738A1 (fr) * 2019-11-25 2021-06-03 Arcelormittal Décapage électro-assisté de l'acier

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITMI20130493A1 (it) * 2013-03-29 2014-09-30 Tenova Spa Metodo per trattare in continuo la superficie di un laminato di acciaio inossidabile in una soluzione a base di acido solforico
CN106181586A (zh) * 2016-07-01 2016-12-07 陕西飞机工业（集团）有限公司 一种不锈钢焊缝或者弯折区域的防腐蚀方法
CN111020683A (zh) * 2019-11-22 2020-04-17 山西太钢不锈钢股份有限公司 一种不锈钢板带酸洗电解电流自动控制方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4363709A (en) * 1981-02-27 1982-12-14 Allegheny Ludlum Steel Corporation High current density, acid-free electrolytic descaling process
JPH06158400A (ja) * 1992-11-24 1994-06-07 Nakagawa Boshoku Kogyo Kk 鋼材表面のスケール除去方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4363709A (en) * 1981-02-27 1982-12-14 Allegheny Ludlum Steel Corporation High current density, acid-free electrolytic descaling process
JPH06158400A (ja) * 1992-11-24 1994-06-07 Nakagawa Boshoku Kogyo Kk 鋼材表面のスケール除去方法

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"CHEMICAL ABSTRACTS + INDEXES, AMERICAN CHEMICAL SOCIETY. COLUMBUS, US", CHEMICAL ABSTRACTS + INDEXES, AMERICAN CHEMICAL SOCIETY. COLUMBUS, US, ISSN: 0009-2258, XP000430754 *
DATABASE WPI Section Ch Week 199427, Derwent World Patents Index; Class M11, AN 1994-222606, XP002197898 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002086199A2 (fr) * 2001-04-24 2002-10-31 Centro Sviluppo Materiali S.P.A. Procede electrolytique continu realise dans une solution acide pour decalaminer des aciers inoxydables, en presence d'effets indirects d'un flux de courant
WO2002086199A3 (fr) * 2001-04-24 2004-03-04 Ct Sviluppo Materiali Spa Procede electrolytique continu realise dans une solution acide pour decalaminer des aciers inoxydables, en presence d'effets indirects d'un flux de courant
WO2011039596A1 (fr) 2009-09-30 2011-04-07 Tenova S.P.A. Unité de préparation de surfaces pour lignes de transformation de bandes métalliques
CN104120438A (zh) * 2014-07-22 2014-10-29 中冶南方工程技术有限公司 一种热轧304奥氏体不锈钢带钢酸洗生产方法
WO2021105738A1 (fr) * 2019-11-25 2021-06-03 Arcelormittal Décapage électro-assisté de l'acier
JP7454045B2 (ja) 2019-11-25 2024-03-21 アルセロールミタル 鋼の電気支援酸洗

Also Published As

Publication number Publication date
DE60105653T2 (de) 2005-09-29
ATE276386T1 (de) 2004-10-15
CN1486373A (zh) 2004-03-31
EP1358367A1 (fr) 2003-11-05
AU2002217449A1 (en) 2002-07-01
ES2232564T3 (es) 2005-06-01
CN1231615C (zh) 2005-12-14
KR20030076589A (ko) 2003-09-26
DE60105653D1 (de) 2004-10-21
EP1358367B1 (fr) 2004-09-15

Similar Documents

Publication Publication Date Title
KR100650961B1 (ko) 무질산 용액을 사용한 전해 산세척 방법
EP1307609B1 (fr) Procede de decapage electrolytique continu pour produits metalliques utilisant des cellules alimentees en courant alternatif
CA2849304C (fr) Decapage d'acier inoxydable dans un bain acide electrolytique, oxydant
EP1358367B1 (fr) Decapage et decalaminage par voie electrolytique continue de l'acier au carbone et de l'acier inoxydable
CN105431574A (zh) 酸洗高铬铁素体不锈钢的方法
JPH0827600A (ja) ステンレス鋼帯の脱スケール方法および装置
JP3792335B2 (ja) ステンレス鋼帯の脱スケールにおける仕上げ電解酸洗方法
WO2002086199A2 (fr) Procede electrolytique continu realise dans une solution acide pour decalaminer des aciers inoxydables, en presence d'effets indirects d'un flux de courant
US3694334A (en) Acid pickling of stainless steels
JP3282829B2 (ja) 合金製品を硝酸の不存在下に酸洗いする方法および酸洗い廃液を回収する方法並びにそのための装置
US2695872A (en) Electrolytic polishing method
US5840173A (en) Process for treating the surface of material of high-grade steel
JPH05295600A (ja) ステンレス鋼帯の連続脱スケール方法及び装置
JPS5959899A (ja) ステンレス鋼帯の電解脱スケ−ル方法
JPS6160920B2 (fr)
JPH0534439B2 (fr)
JPS6396300A (ja) ステンレス冷延、焼鈍鋼帯の電解酸洗方法
JPH0534438B2 (fr)
JPH0711080B2 (ja) 鋼質金属の高速電解溶解法
JPH02310398A (ja) ステンレス冷延鋼材の電解脱スケール法
JPH05247699A (ja) ステンレス鋼帯脱スケール用の中性塩電解処理方法及び装置
JPS63161194A (ja) ステンレス冷延鋼帯の電解脱スケ−ル方法
ITRM20000675A1 (it) Metodo per la descagliatura elettrolitica continua in soluzione neutra di acciai inossidabili in presenza di effetti indiretti del passaggio
JPH01172599A (ja) ステンレス焼鈍鋼帯の電解脱スケール方法
JPH08319600A (ja) ステンレス鋼帯の脱スケール方法及びその装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2001271468

Country of ref document: EP

Ref document number: 1020037008160

Country of ref document: KR

WWE Wipo information: entry into national phase

Ref document number: 018220649

Country of ref document: CN

WWP Wipo information: published in national office

Ref document number: 1020037008160

Country of ref document: KR

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWP Wipo information: published in national office

Ref document number: 2001271468

Country of ref document: EP

WWG Wipo information: grant in national office

Ref document number: 2001271468

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Ref document number: JP