EP0076372A1 - Process for heating aluminium baths - Google Patents
Process for heating aluminium baths Download PDFInfo
- Publication number
- EP0076372A1 EP0076372A1 EP82107246A EP82107246A EP0076372A1 EP 0076372 A1 EP0076372 A1 EP 0076372A1 EP 82107246 A EP82107246 A EP 82107246A EP 82107246 A EP82107246 A EP 82107246A EP 0076372 A1 EP0076372 A1 EP 0076372A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- heating
- aluminizing
- electrolyte
- electrodes
- systems
- 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
- 238000010438 heat treatment Methods 0.000 title claims abstract description 18
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 11
- 238000000034 method Methods 0.000 title claims description 9
- 239000004411 aluminium Substances 0.000 title 1
- 239000003792 electrolyte Substances 0.000 claims abstract description 20
- 238000005269 aluminizing Methods 0.000 claims abstract description 12
- 238000009833 condensation Methods 0.000 claims description 4
- 230000005494 condensation Effects 0.000 claims description 4
- 238000000151 deposition Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000013642 negative control Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000013641 positive control Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/02—Heating or cooling
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S204/00—Chemistry: electrical and wave energy
- Y10S204/09—Wave forms
Definitions
- the invention relates to a method for heating aluminum baths with aprotic electrolyte systems to a predetermined working temperature and keeping them constant during aluminizing.
- Galvanic aluminizing systems which are operated with aprotic, oxygen and water-free, organoaluminum electrolytes, require an operating temperature of over 80 ° C, so that usable aluminum deposits are created under economic conditions.
- the heating and heating of such aluminizing systems is made considerably more difficult because these aluminizing electrolytes are not only particularly sensitive to air and moisture, but are also highly flammable. Therefore, in the known galvanizing aluminizing systems, there is no direct heating, but indirect heating of the electrolyte baths.
- the invention has for its object to provide a simple method for heating aluminum baths with aprotic electrolyte systems that requires little effort and can be easily adjusted to practically any given working temperature.
- the method according to the invention consists in that Joule heat is generated in the aluminum trough by the arrangement of at least two electrodes and charging them with pulse currents of alternating polarity, the clock ratio, the amplitudes and / or the frequency of the alternating pulses preferably being continuously variable.
- So-called square-wave pulse generators can be used to generate the alternating pulses, as is also preferably used for the galvanic deposition of aluminum.
- the pulse generator fulfills two tasks here, namely the reduction of the Al cation to
- condensation surfaces are expediently included.
- the control of the individual current pulses is carried out in such a way that the average cathodic current density remains below the galvanically permissible limit current density of the electrolyte.
- the setting of the cycle ratio in the range of 1: 1 to 10: 1, which is particularly favorable for galvanotechnical reasons, is inversely proportional to the temperature deviation .DELTA.T and means, for example, that if the .DELTA.T increases during the heating phase, the cycle ratio must become smaller and, in extreme cases, the value 1 is approaching.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electroplating Methods And Accessories (AREA)
- Electroplating And Plating Baths Therefor (AREA)
Abstract
Galvanische Aluminieranlagen, welche mit aprotischen Elektrolytsystemen betrieben werden, erfordern eine Betriebstemperatur von über 80°C, um brauchbare Aluminiumabscheidungen zu erzielen. Das Auf- und Beheizen solcher Aluminieranlagen wird bisher mit indirekten Aufheizverfahren bewerkstelligt, z.B. mit einem Heizbad oder Auskreisen des Elektrolyten. Gemäß der Erfindung wird zur Erhöhung des Wirkungsgrades vorgeschlagen, daß die Auf- und Beheizung mit Hilfe von in den Elektrolyt eintauchenden Elektroden erfolgt, die von einem Rechteckimpulsgenerator mit Wechselimpulsen beschickt werden. Vorzugsweise werden als Elektroden die Anoden und Kathoden des Aluminierbades verwendet.Galvanic aluminizing systems that are operated with aprotic electrolyte systems require an operating temperature of over 80 ° C in order to achieve usable aluminum deposits. The heating and heating of such aluminizing systems has hitherto been accomplished using indirect heating processes, e.g. with a heating bath or circling the electrolyte. According to the invention it is proposed to increase the efficiency that the heating and heating is carried out with the aid of electrodes immersed in the electrolyte, which are supplied with alternating pulses by a rectangular pulse generator. The anodes and cathodes of the aluminizing bath are preferably used as electrodes.
Description
Die Erfindung bezieht sich auf ein Verfahren zum Aufheizen von Aluminiumbädern mit aprotischen Elektrolytsystemen auf eine vorgegebene Arbeitstemperatur und Konstanthaltung derselben während des Aluminierens.The invention relates to a method for heating aluminum baths with aprotic electrolyte systems to a predetermined working temperature and keeping them constant during aluminizing.
Galvanische Aluminieranlagen, welche mit aprotischen, sauerstoff- und wasserfreien, aluminiumorganischen Elektrolyten betrieben werden, erfordern eine Betriebstemperatur von über 80° C, damit brauchbare Aluminiumabscheidungen unter wirtschaftlichen Bedingungen entstehen. Das Auf- und Beheizen solcher Aluminieranlagen wird jedoch beträchtlich dadurch erschwert, weil diese Aluminier-Elektrolyte nicht nur besonders luft- und feuchtigkeitsempfindlich sind, sondern auch sehr leicht entflammbar sind. Daher wird bei den bekannten galvanischen Aluminieranlagen keine direkte Beheizung, sondern eine indirekte Beheizung der Elektrolytbäder vorgenommen.Galvanic aluminizing systems, which are operated with aprotic, oxygen and water-free, organoaluminum electrolytes, require an operating temperature of over 80 ° C, so that usable aluminum deposits are created under economic conditions. The heating and heating of such aluminizing systems, however, is made considerably more difficult because these aluminizing electrolytes are not only particularly sensitive to air and moisture, but are also highly flammable. Therefore, in the known galvanizing aluminizing systems, there is no direct heating, but indirect heating of the electrolyte baths.
Bei den in den deutschen Patentschriften 25 37 256, 25 37 285 und 27 16 805 beschriebenen Vorrichtungen zum galvanischen Abscheiden von Aluminium wird dieses Problem dadurch-gelöst, daß der Aluminiertrog mit einem Ölmantel umgeben ist, in welchem sich Heizstäbe befinden. Bei anderen bekannten Vorrichtungen wird dieses Problem dadurch gelöst, daß man mit Hilfe einer Förderpumpe den Elektrolyt auskreist und diesen über einen Wärmetauscher schickt.In the devices for the galvanic deposition of aluminum described in German patents 25 37 256, 25 37 285 and 27 16 805, this problem is solved in that the aluminum trough is surrounded by an oil jacket in which heating elements are located. In other known devices, this problem is solved by circulating the electrolyte with the aid of a feed pump and sending it through a heat exchanger.
Beide Verfahren haben folgende Nachteile:
- Relativ große Wärmeverluste, hohe Wärmeisolationskosten, hohe Aufwendungen, wenn Rohrleitungen und Pumpen erforderlich sind, und zum Teil kann auf eine relativ aufwendige Temperaturregelung nicht verzichtet werden.
- Relatively large heat losses, high heat insulation costs, high expenditure when pipelines and pumps are required, and in some cases a relatively complex temperature control cannot be dispensed with.
Der Erfindung liegt die Aufgabe zugrunde, ein einfaches Verfahren zum Aufheizen von Aluminiumbädern mit aprotischen Elektrolytsystemen anzugeben, das wenig Aufwand erfordert und praktisch auf jede vorgegebene Arbeitstemperatur leicht eingestellt werden kann. Das erfindungsgemäße Verfahren besteht darin, daß im Aluminiertrog durch die Anordnung mindestens zweier Elektroden und Beschickung dieser mit Impulsströmen wechselnder Polarität Joul'sche Wärme erzeugt wird, wobei das Taktverhältnis, die Amplituden und/oder die Frequenz der Wechselimpulse vorzugsweise stufenlos veränderbar sind.The invention has for its object to provide a simple method for heating aluminum baths with aprotic electrolyte systems that requires little effort and can be easily adjusted to practically any given working temperature. The method according to the invention consists in that Joule heat is generated in the aluminum trough by the arrangement of at least two electrodes and charging them with pulse currents of alternating polarity, the clock ratio, the amplitudes and / or the frequency of the alternating pulses preferably being continuously variable.
Dabei wird von der Tatsache Gebrauch gemacht, daß die bekannten aprotischen Elektrolytsysteme eine relativ geringe Leitfähigkeit und damit großen Widerstand aufweisen, welches die Aufheizung erleichtert. Vorzugsweise sind als Elektroden die Anoden und Kathoden des Aluminierbades selbst verwendet. Zwischen diesen Elektroden wird eine Wechselspannung mit bestimmter Frequenz und variierbaren unterschiedlichen kathodischen (t1) und anodischen (t2) Impulszeiten (Taktverhältnis = t1:t2) sowie mit entsprechender Amplitudenhöhe angelegt, so daß aufgrund des auftretenden Stromflusses im Elektrolyten ein ganz bestimmter Betrag an Joule'scher Wärme entsteht.Use is made of the fact that the known aprotic electrolyte systems have a relatively low conductivity and thus a high resistance, which facilitates heating. The anodes and cathodes of the aluminizing bath itself are preferably used as electrodes. Between these electrodes, an alternating voltage with a certain frequency and variable different cathodic (t 1 ) and anodic (t 2 ) pulse times (clock ratio = t 1 : t 2 ) and with a corresponding amplitude level is applied, so that due to the current flow occurring in the electrolyte a very specific one Amount of Joule heat arises.
Zur Erzeugung der Wechselimpulse können sog. Rechteck-impulsgeneratoren verwendet werden, wie man sie auch vorzugsweise für die galvanische Abscheidung von Aluminium bereits verwendet. Der Impulsgenerator erfüllt hierbei zwei Aufgaben, nämlich die Reduktion des Al-Kations zumSo-called square-wave pulse generators can be used to generate the alternating pulses, as is also preferably used for the galvanic deposition of aluminum. The pulse generator fulfills two tasks here, namely the reduction of the Al cation to
Metall und die Aufrechterhaltung der Elektrolyttemperatur in Zusammenwirkung mit einem Kondensationssystem für die Lösungsmitteldämpfe. Bei der Regelung der Temperatur des Bades werden zweckmäßigerweise die Kondensationsflächen mit einbezogen.Metal and maintaining electrolyte temperature in conjunction with a solvent vapor condensation system. When regulating the temperature of the bath, the condensation surfaces are expediently included.
Die Konstanthaltung der Elektrolyttemperatur, d.h. das Ausregeln der Regelabweichung auf Null, ist möglich, da letztlich die negative Regelabweichung als Funktion der Amplitudenhöhe und des Taktverhältnisses des Wechsel- ! stroms dargestellt werden kann. Die Stromwärme, die bei der Abscheidung von Aluminium auftritt (positive Regelabweichung) ist jedoch leicht in Form von Kondensationswärme abführbar, da bei aprotischen Elektrolytsystemen diese etwa zur Hälfte aus organischen Lösungsmitteln bestehen.Keeping the electrolyte temperature constant, i.e. It is possible to correct the control deviation to zero, because ultimately the negative control deviation as a function of the amplitude and the clock ratio of the alternating! current can be represented. The heat of electricity that occurs during the deposition of aluminum (positive control deviation) can, however, be easily dissipated in the form of condensation heat, since in aprotic electrolyte systems these consist approximately half of organic solvents.
Hierbei ist zu beachten, daß die Steuerung der einzelnen Stromimpulse so durchgeführt wird, daß die mittlere kathodische Stromdichte unterhalb der galvanisch zulässigen Grenzstromdichte des Elektrolyten bleibt. Die aus galvanotechnischen Gründen besonders günstige Einstellung des Taktverhältnisses im Bereich.von 1:1 bis 10:1 ist umgekehrt proportional zur Temperaturabweichung Δ T und bedeutet beispielsweise, daß bei größerwerdendem Δ T während der Aufheizphase das Taktverhältnis kleiner werden muß und im Extremfall sich dem Wert 1 nähert.It should be noted here that the control of the individual current pulses is carried out in such a way that the average cathodic current density remains below the galvanically permissible limit current density of the electrolyte. The setting of the cycle ratio in the range of 1: 1 to 10: 1, which is particularly favorable for galvanotechnical reasons, is inversely proportional to the temperature deviation .DELTA.T and means, for example, that if the .DELTA.T increases during the heating phase, the cycle ratio must become smaller and, in extreme cases, the value 1 is approaching.
Beispiel:
- 1. Aufheizen des Galvanisier-Elektrolyten Um den Elektrolyten in der Galvanisieranlage von Raumtemperator z.B. auf 100° C zu bringen, werden am Impulsgenerator folgende Werte eingestellt:
- Frequenz = 10000 Hz, Taktverhältnis = 1:1 (arithet. Mittelwert des Stromes = 0; keine Al-Abscheidung) kath. Stromdichte 3 A/dm2, Spannung 10 - 50 V.
- 2. Abscheiden von Al mit gleichzeitiger Regelung der Temperatur
Frequenz = 10 - 100 Hz, Taktverhältnis variierbar von 1:1 bis 10:1; kath. Stromdichte 0,5 bis 3 A/dm2. - Dieser Regelmechanismus funktioniert bei Zellen mit kleinerer Beschichtungsleistung. Hierbei ist das Verhältnis der erzeugten und abgestrahlten Wärme etwa vergleichbar. Bei Zellen hoher Beschichtungsleistung wird der Mehranteil erzeugter Stromwärme über verdampfendes Lösungsmittel abgeführt, welches an den kühleren Flächen der mit dem Elektrolyttrog dicht verbundenen Haube kondensiert und wieder in das Elektrolytsystem zurückläuft.
- 1. Heating the electroplating electrolyte To bring the electrolyte in the electroplating system from room temperature to, for example, 100 ° C, the following values are set on the pulse generator:
- Frequency = 10000 Hz, clock ratio = 1: 1 (arithmetic mean value of the current = 0; no Al separation) cath. Current density 3 A / dm 2 , voltage 1 0 - 50 V.
- 2. Separation of Al with simultaneous regulation of the temperature
Frequency = 10 - 100 Hz, clock ratio variable from 1: 1 to 10: 1; cath. Current density 0.5 to 3 A / dm 2 . - This control mechanism works for cells with lower coating performance. The ratio of the heat generated and radiated is roughly comparable. In the case of cells with a high coating capacity, the majority of the electricity heat generated is dissipated via evaporating solvent, which condenses on the cooler surfaces of the hood which is tightly connected to the electrolyte trough and runs back into the electrolyte system.
Claims (4)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3138072A DE3138072C1 (en) | 1981-09-24 | 1981-09-24 | Process for heating aluminizing baths with aprotic electrolit systems |
| DE3138072 | 1981-09-24 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0076372A1 true EP0076372A1 (en) | 1983-04-13 |
| EP0076372B1 EP0076372B1 (en) | 1986-01-15 |
Family
ID=6142528
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP82107246A Expired EP0076372B1 (en) | 1981-09-24 | 1982-08-10 | Process for heating aluminium baths |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4382844A (en) |
| EP (1) | EP0076372B1 (en) |
| DE (2) | DE3138072C1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4596636A (en) * | 1984-08-20 | 1986-06-24 | Alumatec, Inc. | Method for the electrodeposition of metal and method of workpiece pretreatment therefor |
| GB2257715B (en) * | 1991-07-19 | 1994-06-29 | Univ Hull | Coating metallic substrates |
| ATE151821T1 (en) * | 1992-02-08 | 1997-05-15 | Lpw Anlagen Gmbh | SYSTEM FOR OPERATING A POWERLESS ELECTROCHEMICAL BATH WITH BATH HEATING BY MICROWAVES |
| DE202006017090U1 (en) * | 2006-11-07 | 2008-03-20 | BEGO Bremer Goldschlägerei Wilh. Herbst GmbH & Co. KG | Heated electropolishing device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4181584A (en) * | 1978-12-06 | 1980-01-01 | Ppg Industries, Inc. | Method for heating electrolytic cell |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2537256C3 (en) * | 1975-08-21 | 1979-05-17 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Device for the galvanic deposition of aluminum |
| CH603832A5 (en) * | 1975-08-21 | 1978-08-31 | Siemens Ag | |
| DE2716805C3 (en) * | 1977-04-15 | 1979-10-31 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Device for the galvanic deposition of aluminum |
-
1981
- 1981-09-24 DE DE3138072A patent/DE3138072C1/en not_active Expired
-
1982
- 1982-08-10 EP EP82107246A patent/EP0076372B1/en not_active Expired
- 1982-08-10 DE DE8282107246T patent/DE3268547D1/en not_active Expired
- 1982-08-23 US US06/410,520 patent/US4382844A/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4181584A (en) * | 1978-12-06 | 1980-01-01 | Ppg Industries, Inc. | Method for heating electrolytic cell |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3138072C1 (en) | 1982-11-04 |
| EP0076372B1 (en) | 1986-01-15 |
| DE3268547D1 (en) | 1986-02-27 |
| US4382844A (en) | 1983-05-10 |
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