DE4403409A1 - Moisture sensor - Google Patents

Moisture sensor

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Publication number
DE4403409A1
DE4403409A1 DE19944403409 DE4403409A DE4403409A1 DE 4403409 A1 DE4403409 A1 DE 4403409A1 DE 19944403409 DE19944403409 DE 19944403409 DE 4403409 A DE4403409 A DE 4403409A DE 4403409 A1 DE4403409 A1 DE 4403409A1
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DE
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Patent type
Prior art keywords
pref
poly
moisture
polymer
consists
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Withdrawn
Application number
DE19944403409
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German (de)
Inventor
Ludwig Prof Dr Brehmer
Mathias Dr Hahn
Michael Seifert
Roland Dr Ing Wernecke
Werner Dr Jaeger
Reiner Dipl Ing Wonneberger
Christian Dipl Ing Dr Zehner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZEHNER CHRISTIAN DIPL ING DR H
Original Assignee
ZEHNER CHRISTIAN DIPL ING DR H
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means
    • G01N27/02Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating the impedance of the material
    • G01N27/04Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating the impedance of the material by investigating resistance
    • G01N27/12Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating the impedance of the material by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/125Composition of the body, e.g. the composition of its sensitive layer
    • G01N27/126Composition of the body, e.g. the composition of its sensitive layer comprising organic polymers
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means
    • G01N27/02Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating the impedance of the material
    • G01N27/04Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating the impedance of the material by investigating resistance
    • G01N27/12Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating the impedance of the material by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/121Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating the impedance of the material by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid for determining moisture content, e.g. humidity, of the fluid

Abstract

A moisture sensor consists of a substrate coated with a layer of poly-dimethyl-diallyl-ammonium salt (I) as moisture-sensitive polymer. Pref. a suitable substrate consists of Al2O3 ceramic, and pref. initiator is 4,4'-bisazido-stilbene- 2,2'-disulphonic acid. Pref. suitable counter-ions for (I) are chloride, nitrate, sulphate, tosylate, acetate, citrate or tartrate; pref. (I) is poly-dimethyl-diallyl-ammonium chloride (poly-DADMAC) or a copolymer of DADMAC with N-vinylpyrrolidone. The polymer also contains a UV-active crosslinking initiator. The polymer coating is applied by dipping, and a structured crosslinking effect can be obtd. by directed UV irradiation.

Description

Die Erfindung betrifft einen Polymer-Feuchtesensor, der auf einem Substrat eine dünne Schicht eines Polymers aufweist. The invention relates to a polymer humidity sensor having on a substrate a thin layer of a polymer.

Solche Feuchtesensoren sind bekannt: DE-PS 37 34 614. Such humidity sensors are known: DE-PS 37 34 614th

Aus SAKAI: J. o. the Electrochem. From SAKAI: J. o the Electrochem.. Soc., Vol. 136, No. Soc., Vol. 136, No. 1, 1989 sind Untersuchungen zum Widerstandsverhalten solcher Feuchtesensoren bekannt, aus denen sich ergibt, daß Polymer-Feuchtesensoren nach dem Stand der Technik ein relativ schlechtes zeitliches Verhalten bei Feuchtigkeits änderungen, dh eine relativ lange Reaktionszeit, und darüber hinaus ein unbefriedigendes Widerstandsver halten aufweisen. 1, 1989 Studies on the resistance behavior of such moisture sensors are known, from which it follows that polymer humidity sensors according to the prior art, a relatively poor temporal behavior when moisture changes, that have a relatively long reaction time and moreover keep an unsatisfactory Widerstandsver.

Es ist Aufgabe der Erfindung, bei Feuchtesensoren der beschriebenen Gattung Widerstandsverhalten und zeitliches Verhalten bei Feuchtigkeitsänderungen zu verbessern. It is an object of the invention to improve resistance behavior and temporal behavior when moisture changes in humidity sensors of the type described.

Diese Aufgabe wird durch einen Feuchtesensor mit den Merk malen des 1. Patentanspruches gelöst. This object is achieved by a humidity sensor with the characteristics set of the first patent claim resolved.

Die Unteransprüche beinhalten vorteilhafte Weiterbildungen der Erfindung. The subclaims contain advantageous developments of the invention.

Es hat sich überraschenderweise gezeigt, daß die Verwendung von Poly-dimethyl-diallyl-ammoniumsalzen als spezielle kationische Polyelektrolyten als feuchtesensible Polymere zu Feuchtesensoren mit außerordentlich günstigen Eigen schaften führt. It has surprisingly been found that the use of poly-dimethyl-diallyl-ammonium salts as cationic polyelectrolyte as a special moisture sensitive polymers to humidity sensors having extremely favorable dead leads properties.

Zum einen besitzen die erfindungsgemäßen Feuchtesensoren ein besseres Widerstandsverhalten bei dc-Messungen als solche nach dem Stand der Technik. Firstly humidity sensors to the invention have a better resistance behavior in dc measurements as such by the prior art. Sie liegen für relative Luftfeuchten von 20 . They are for relative humidities of the 20th . , . , 95% bei Werten zwischen 2 kΩ und 1 MΩ. 95% at values ​​between 2 kΩ and 1 M.

Zum anderen weisen die erfindungsgemäßen Feuchtesensoren ein besseres zeitliches Verhalten bei Feuchteänderungen auf. Secondly, have humidity sensors to the invention have a better temporal behavior with changes in humidity. Dies gilt speziell für die Reaktionszeit; This is specific to the reaction time; so stellen sich innerhalb von wenigen Minuten bei veränderten Feuchtebedin gungen stabile Zustände ein. so imagine within minutes with changing conditions Feuchtebedin a stable states. Bei Feuchtigkeitszunahme wird innerhalb einer Minute etwa ein Wert von 95% des Endwertes erreicht. When moisture gain as a value of 95% of final value is achieved within one minute. Bei Feuchtigkeitsabnahme verlängert sich dieser Wert etwa um das 3fache. When moisture decrease this value extended by about 3-fold.

Die erfindungsgemäß verwendeten Poly-dimethyl-diallyl-ammonium salze können unterschiedliche Gegenionen haben: Chlorid, Nitrat, Sulfat, Tosylat, Acetat, Citrat, Tartat. The poly-dimethyl-diallyl-ammonium salts used in this invention may have different counter-ions: chloride, nitrate, sulfate, tosylate, acetate, citrate, tartrate.

Besonders vorteilhaft ist die Anwendung von Poly-dimethyl diallyl-ammoniumchlorid. Particularly advantageous is the use of poly diallyl-dimethyl-ammonium chloride is.

Sehr gute Ergebnisse werden auch bei der Verwendung von Copolymeren des Dimethyl-diallyl-ammoniumchlorides mit N-Vinylpyrrolidon erzielt. Very good results are the dimethyl diallyl ammonium chlorides achieved in the use of copolymers with N-vinylpyrrolidone. Dadurch ist die Ladungsdichte des Polymers gezielt variierbar. Thus, the charge density of the polymer is selectively variable.

Eine weitere Verbesserung der Eigenschaften, insbesondere auch der Verringerung der Wasserlöslichkeit, der erfindungs gemäßen Feuchtesensoren ist durch eine Vernetzung, insbesondere Photovernetzung, unter vorheriger Beimischung UV-aktiver Zusatzstoffe möglich. A further improvement in the properties, in particular the reduction of the water solubility of the humidity sensors fiction, modern by crosslinking, in particular photocrosslinking, it is possible with prior blending UV-active additives. Besonders geeignet als solcher Zusatzstoff ist 4,4′-Bisazidostilben-2,2′- disulfonsäure. Particularly suitable as such additive 4,4 Bisazidostilben-2,2'-disulfonic is.

Für die Herstellung der erfindungsgemäßen Feuchtesensoren hat sich das Dipping als Verfahren zum Bilden der Polymerschicht letztlich als besonders günstig erwiesen. For the production of humidity sensors according to the invention, the dipping has ultimately proven method of forming the polymer layer to be particularly favorable. Dabei wird die Filmbildung auf einem geeigneten Substrat, z. Here, the film formation on a suitable substrate, eg. B. Al₂O₃-Keramik, durch definiertes Tauchen in eine Lösung und Herausziehen realisiert. B. Al₂O₃ ceramics, realized by a defined immersion in a solution and pulling out. Die überschüssige Lösung wird durch die Ober flächenspannung der Lösung im Tauchgefäß bei entsprechend langsamem Bewegungsablauf vom senkrecht hängenden und gut benetzten Substrat abgezogen. The excess solution is through the top of the solution surface tension removed in diving vessel with a correspondingly slow movement of the vertically hanging and well wetted substrate.

Die verwendeten Polymere zeichnen sich durch eine hohe Sensibilität gegenüber Wasser aus. The polymers used are characterized by a high sensitivity to water. Das betrifft sowohl die Leitfähigkeit als auch die Löslichkeit. This applies to both the conductivity and solubility.

Aus diesem Grunde ist eine Vernetzung der erzeugten Schicht auf dem Substrat sinnvoll. For this reason, a crosslinking of the layer formed on the substrate is useful.

Vernetzungen nach der Schichtherstellung lassen sich auf verschiedene Arten durchführen: Networks after the film formation can be performed in several ways:

Bekannt ist die Bestrahlung von Polymeren, so daß bestimmte Stellen des Makromoleküls aktiviert werden und eine Vernetzung zwischen diesen Molekülen erfolgen kann. is known, the irradiation of polymers, so that certain points of the macromolecule to be activated and carried out a cross-linking between these molecules can.

Bekannt ist ferner das Zumischen von Monomeren und Bestrahlung der Mischung, um die Monomereinheiten als Kettenglieder zwischen den aktivierten Stellen der Makromoleküle einzusetzen. Also known is the mixing of monomers, and irradiating the mixture in order to use the monomer as chain members between the activated sites of the macromolecules.

In beiden Fällen erfolgt die Aktivierung durch Gamma strahlung. In both cases, the activation is carried out by gamma radiation.

Es ist auch vorgeschlagen, einen Vernetzer einzusetzen, der nach Energieeinstrahlung Verkettungen zwischen den Makromolekülen herstellt. It is also proposed to use a crosslinking agent that establishes linkages between the macromolecules by energy irradiation. Dabei erfolgt dann die Aktivierung durch UV-Strahlung. The activation by UV irradiation is then carried.

Durch gezielte UV-Bestrahlung läßt sich dabei weiterhin auch, fall erforderlich, eine strukturierte Vernetzung erreichen. Through selective UV irradiation continues also drops thereby required to achieve a structured networking. Beispielsweise ist ein flächenhaftes, strukturiertes Ausarbeiten von Sensorbeschichtungen durch Ablösen der unvernetzten Fläche möglich. For example, a planar, structured elaboration of sensor coatings by peeling the uncrosslinked surface is possible.

Claims (7)

  1. 1. Feuchtesensor, bestehend aus einer auf ein Substrat aufgezogenen Schicht eines feuchtesensiblen Polymers, dadurch gekennzeichnet, daß das Polymer ein Poly-dimethyl-diallyl-ammoniumsalz ist. 1. humidity sensor, consisting of a drawn onto a substrate layer of a moisture-sensitive polymer, characterized in that the polymer is a poly-dimethyl-diallyl-ammonium salt.
  2. 2. Feuchtesensor nach Anspruch 1, dadurch gekennzeichnet, daß das Polymer als Gegenionen Chlorid, Nitrat, Sulfat, Tosylat, Acetat, Citrat oder Tartrat aufweist. 2. Humidity sensor according to claim 1, characterized in that the polymer has as counterions chloride, nitrate, sulfate, tosylate, acetate, citrate or tartrate.
  3. 3. Feuchtesensor nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Polymer ein Poly-dimethyl-diallyl-ammoniumchlorid ist. 3. Humidity sensor according to claim 1 or 2, characterized in that the polymer is a poly-dimethyl-diallyl-ammonium chloride.
  4. 4. Feuchtesensor nach Anspruch 1 bis 3, dadurch gekennzeichnet, daß das Polymer ein Copolymer des Dimethyl-diallyl ammoniumchlorides mit N-Vinylpyrrolidon ist. 4. Humidity sensor according to claim 1 to 3, characterized in that the polymer is a copolymer of dimethyl diallyl ammonium chloride with N-vinylpyrrolidone.
  5. 5. Feuchtesensor nach Anspruch 1 bis 4, dadurch gekennzeichnet, daß dem Polymer ein UV-aktiver Zusatzstoff zur Vernetzung nach dem Aufziehen beigemischt ist. 5. Humidity sensor according to claim 1 to 4, characterized in that the polymer is a UV-active additive is added for cross-linking after coating.
  6. 6. Feuchtesensor nach Anspruch 1 bis 5, dadurch gekennzeichnet, daß das Polymer durch Dipping auf das Substrat aufziehbar ist. 6. Moisture sensor according to claim 1 to 5, characterized in that the polymer can be pulled by dipping onto the substrate.
  7. 7. Feuchtesensor nach Anspruch 1 bis 6, dadurch gekennzeichnet, daß durch gezielte UV-Bestrahlung eine strukturierte Vernetzung erreichbar ist. 7. Moisture sensor according to claim 1 to 6, characterized in that a structured crosslinking is achievable through specific UV-irradiation.
DE19944403409 1994-02-04 1994-02-04 Moisture sensor Withdrawn DE4403409A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19944403409 DE4403409A1 (en) 1994-02-04 1994-02-04 Moisture sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19944403409 DE4403409A1 (en) 1994-02-04 1994-02-04 Moisture sensor

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0676636A2 (en) * 1994-03-31 1995-10-11 TDK Corporation Humidity sensor and method for making
DE19963188A1 (en) * 1998-12-28 2000-09-14 Tdk Corp Moisture sensitive elements utilizing moisture absorbing polymer
EP1369683A1 (en) * 2001-03-13 2003-12-10 TDK Corporation Humidity sensor element and method for manufacture thereof
FR2923218A1 (en) * 2007-11-06 2009-05-08 Rhodia Operations Sas Composition, useful to treat and/or modify surface e.g. textile, comprises copolymer comprising cationic units A and other units B, where unit A comprises quaternary ammonium/inium group, and unit B comprises vinyl-lactam
WO2009059878A1 (en) * 2007-11-06 2009-05-14 Rhodia Operations Copolymer for processing or modifying surfaces
FR2928377A1 (en) * 2008-03-06 2009-09-11 Rhodia Operations Sas Composition, useful to treat and/or modify surface e.g. textile, comprises copolymer comprising cationic units and other units, where the cationic unit comprises quaternary ammonium/inium group and other unit comprises vinyl-lactam

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0676636A2 (en) * 1994-03-31 1995-10-11 TDK Corporation Humidity sensor and method for making
EP0676636A3 (en) * 1994-03-31 1996-11-13 Tdk Corp Humidity sensor and method for making.
DE19963188A1 (en) * 1998-12-28 2000-09-14 Tdk Corp Moisture sensitive elements utilizing moisture absorbing polymer
US6342295B1 (en) 1998-12-28 2002-01-29 Tdk Corporation Moisture sensor
EP1369683A1 (en) * 2001-03-13 2003-12-10 TDK Corporation Humidity sensor element and method for manufacture thereof
EP1369683A4 (en) * 2001-03-13 2008-06-18 Tdk Corp Humidity sensor element and method for manufacture thereof
FR2923218A1 (en) * 2007-11-06 2009-05-08 Rhodia Operations Sas Composition, useful to treat and/or modify surface e.g. textile, comprises copolymer comprising cationic units A and other units B, where unit A comprises quaternary ammonium/inium group, and unit B comprises vinyl-lactam
WO2009059878A1 (en) * 2007-11-06 2009-05-14 Rhodia Operations Copolymer for processing or modifying surfaces
US9096817B2 (en) 2007-11-06 2015-08-04 Rhodia Operations Copolymer for processing or modifying surfaces
FR2928377A1 (en) * 2008-03-06 2009-09-11 Rhodia Operations Sas Composition, useful to treat and/or modify surface e.g. textile, comprises copolymer comprising cationic units and other units, where the cationic unit comprises quaternary ammonium/inium group and other unit comprises vinyl-lactam

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