Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
2002-07-31
2004-07-27
Jackson, Monique R. (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S325000, C359S270000, C359S273000
Reexamination Certificate
active
06767624
ABSTRACT:
The present invention relates to composite elements which are particularly suitable for use in electrochromic windows, to electrochromic windows and glazing comprising a composite element of this type, and to a process for the production of these composite elements.
Optically transparent polymeric solid electrolytes are known in principle. They are used, in particular, in electrochromic systems, for example in electrochromic glazing. In electrochromic glazing, the light transparency can be regulated reversibly and steplessly by application of electric potentials. The structure of systems of this type is described, for example, in EP-A 461 685, DE-A 36 43 690 and U.S. Pat. No. 5,244,557. Electrochromic glazing typically has the following layer sequence: glass pane—transparent electrically conductive layer—electrochromic electrode—electrolyte—counterelectrode—transparent electrically conductive layer—glass pane.
Electrochromic functional layers are described, for example, in Material Research, Vol. 2, No. 1 (1999), pp. 1 to 9.
Solid electrolytes in these systems take on the job of transporting cations to the electrochromic electrode or away from the electrode, depending on the polarity of the applied electric field. The electrochromic electrode changes its color due to this process. Solid electrolytes which are suitable for use in electrochromic systems have to satisfy a multiplicity of different requirements. They must have high electrical conductivity and preferably also optical transparency in the visible spectral region, and in addition it must be possible for them to be employed in a broad temperature range without adverse effects on their optical, electrical and mechanical properties.
EP-A 461 685 and EP-A 499 115 disclose solid electrolytes comprising polar polymers based on polyethylene oxide, polyethylene oxide copolymers or graft copolymers and comprising conductive salts which are soluble in these polar polymers, in particular Li salts. The solid electrolytes are prepared by dissolving the starting materials in suitable organic solvents, coating the substrates therewith and evaporating the solvent again.
U.S. Pat. No. 5,244,557 discloses electrochromic glazing comprising an electrolyte made from polyethylene oxide and P
2
O
5
. The individual layers of the electrochromic glazing here are bonded to one another, for example, at high temperatures and high pressure.
EP-A 1 056 097 discloses optically transparent solid electrolytes which are built up from a polymeric binder, a filler, a conductive salt and an ion-solvating plasticizer. EP-A 1 056 097 likewise mentions the use of solid electrolytes of this type in electrochromic systems and displays. Here, the solid electrolyte, in particular the polymeric binder present in the solid electrolyte, must be matched to the electrochromic functional layer in order to guarantee the function of the electrochromic window.
Based on this prior art, it is an object of the present invention to provide composite elements which can be used as electrochromic windows and in which, at the same time, a broad range of polymeric binders can be employed for the solid electrolyte layer.
We have found that this object is achieved by a composite element comprising
A) at least one layer A at least comprising a solid electrolyte Al which comprises at least the following components:
i) at least one filler I having a primary particle size of from 1 nm to 20 &mgr;m,
ii) at least one polymeric binder II,
B) at least one adhesion-promoting layer B having a thickness of <100 &mgr;m;
C) at least one component C which provides the composite element with electrochromic properties.
For the purposes of the present invention, the term “electrochromic properties” is taken to mean that a composite element according to the invention exhibits a change in light absorption, in particular in the visible region, on application of a voltage.
It is preferred in accordance with the invention that the at least one component C in the composite element is present in a layer CI.
The layer CI according to the invention can be applied, for example, by vapor deposition. If the layer CI is applied by wet-chemical methods, for example by dipping methods or sol-gel methods, it may, in addition to the at least one component C, comprise further additives and auxiliaries known to the person skilled in the art. Additives and auxiliaries of this type are, for example, binders, precipitants or also flow assistants.
However, it is likewise possible for the purposes of the present invention for component C to be present, for example, in layer A.
If component C is present in layer A, component C is particularly preferably a compound which has different light absorption, in particular in the visible region, in different oxidation states and can be converted reversibly from one oxidation state into another. For example, suitable compounds are those which are colorless in one oxidation state and colored in a second. Compounds of this type are, for example, dihydrophenazines or similar compounds, as described in U.S. Pat. No. 6,249,369 or U.S. Pat. No. 5,278,693.
The adhesion-promoting layer B according to the invention enables the adhesion to be set independently of the polymeric binder II, enabling a larger number of polymeric binders to be employed for the solid electrolyte Al according to the invention. In addition, the adhesion-promoting layer B prevents direct contact of the polymeric binder II with layer CI, also enabling use of polymeric binders which would be unstable in a layer structure with direct contact with layer CI or when subjected to cyclic current.
Particularly suitable for use in electrochromic systems are solid electrolytes Al which are optically transparent.
In a preferred embodiment, the present invention therefore relates to a composite element comprising a solid electrolyte Al which has at least one of properties (1) to (3):
(1) light absorption <20%,
(2) conductivity at 20° C. greater than 10
−7
S/cm,
(3) glass transition temperature T
g
<−30° C.
For the purposes of the present invention, the solid electrolyte Al preferably satisfies all of properties (1) to (3).
The conductivity of the solid electrolyte Al at 20° C. is, in accordance with the invention, preferably greater than 10
−7
S/cm, in particular greater than 10
−5
S/cm.
The solid electrolyte Al according to the invention comprises, in accordance with the invention, a filler I having a primary particle size of from 1 nm to 20 &mgr;m, for example from 1 nm to 1000 nm, in particular from 1 nm to 500 nm, preferably from 1 nm to 300 nm, particularly preferably from 1 nm to 100 nm or also from 5 to 10 nm.
In the case of spherical or approximately spherical particles, these data relate to the diameter, while in the case of particles of irregular shape, for example needle-shaped particles, they relate to the longest axis. In accordance with the invention, preference is given to a very finely divided solid in which the primary particle size is in the region of the wavelength of visible light in order that an optically transparent solid electrolyte is obtained.
Examples of suitable fillers are polymer particles, which may also be crosslinked, such as those comprising polystyrene, polycarbonate or polymethyl methacrylate (for example Agfaperl®). Also suitable are, in particular, inorganic fillers having a primary particle size of from 1 to 300 nm. Examples of suitable inorganic fillers are glass powder, glass nanoparticles, for example Monospher® (Merck), and glass microparticles, for example Spheriglas® (Potters-Ballotini). Also suitable are inorganic oxides and mixed oxides, in particular of the elements silicon, aluminum, magnesium, titanium or calcium. Examples of fillers of this type are silicon dioxide, in particular pyrogenic oxides, for example Aerosil® (Degussa), silicates, for example talc, pyrophyllite, wollastonite, aluminosilicates, for example feldspar, or zeolites. The fillers may also be coated with suitable dispersion aids, adhesion promoters or hydrophobicizing agents
BASF - Aktiengesellschaft
Jackson Monique R.
Keil & Weinkauf
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