Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-01-30
2002-12-03
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S028000, C522S113000, C522S114000, C522S119000, C522S120000, C522S121000, C522S090000, C522S096000, C522S104000, C522S107000, C522S150000, C430S020000, C252S600000, C428S001100, C428S001550, C428S001540, C428S001330
Reexamination Certificate
active
06489377
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing thermotropic resin systems that comprise at least one matrix polymer including at least one (thermotropic) monomer compound which cannot be mixed with the matrix polymer, and the structure of which cannot be affected by temperature changes, whereby the matrix polymer and the thermotropic monomer compound are selected in such a way that their refraction indices are almost the same in a temperature range that is below the temperature required for structural change and that reaches the temperature of structural change of the thermotropic monomer compound, the casting resin system being therefore translucent or transparent in this temperature range, as well as the utilization of such thermotropic cast resin systems.
There are already several known thermotropic systems, especially in connection with the shading of glass surfaces.
2. Description of the Related Art
From the generic DE 44 33 090 A1 a thermo-optical polymer material is known, which consists of at least one matrix polymer compound and one monomer compound, whereby the matrix polymer and the monomer compound are chosen in such a way that their refraction indices in the temperature range below the temperature required for structural change up to the temperature for structural change of the monomer compound are almost equal, and the polymer material is thus translucent and transparent in this temperature range. In this case, the polyesters are suggested as the matrix polymers, and as the monomer compounds, alkanes with C10 to C25 are preferably proposed.
From the German patent application DE 196 42 886.6 it is known that on the basis of completely dissociated polymers, thermotropic systems can be formulated which are utilized for the production of thermotropic coatings. In this case, at first a coating solution is produced (for example with xylol as a solvent). The application of the coating solution is carried out with known paint-technological coating processes, such as, for example, blade-coating, spraying or flow-coating. After the coating solution is applied the solvent is vaporized and subsequently the cross linkage is thermally induced. After cooling and intermediate storage the application of the cover coat is preferably made. The disadvantage of this process consists in that during the vaporization of the solvent poisonous vapors can be generated. This can lead to environmental contamination as well as require higher investment costs for work safety. Furthermore, because of the costly drying process the manufacturing process it is only usable for exposed surfaces or for coatings with a limited film thickness, so that the possibility of applying it for large industries is limited.
A further development is based on a thermotropic gel which consists primarily of colloidal parts of a polyether-water mixture, which is enclosed in a gel-like layer of a vinyl-carboxyl-water mixture. In this case a tenside surface serves as the solubilizer. When a critical temperature is exceeded, on the one hand the water linked to the macromolecule will be split off to the outer solvent. At the same time a temperature-dependent felting of the macromolecules takes place. In addition to this partial growth the relative refractive index of the particles is increased by the water separation (See also European patent 86 904 133). These thermotropic gels can, for example, be filled into the intermediate space between window panes in order to produce thermo-optical glazing. The disadvantage of this development, however, consists in that the generally highly viscous systems can only be used for filling at a high expenditure, and that the edge seals must be made in such a way that they seal against water vapor diffusion as well being resistant to chemicals, in order to prevent them from drying out. In addition to high production costs the long term stability of such a glazing is generally strongly limited.
On the basis of the DE 44 33 090 A1 the present invention is based on the objective of creating a process for the production of thermotropic resin casting systems, which makes it possible to produce thermotropic casting resin systems of long-term durability and of any desired shape and size, and to do so rapidly, cost-effectively, and in a way which is safe for the environment.
This task is achieved by a production process according to claim
1
, and as far as the utilization is concerned by the characteristics of claim
2
.
SUMMARY OF THE INVENTION
Due to the fact that the thermotropic casting resin systems (T-OPAL) are kept for hardening by dissolving the monomer compound in a matrix solution, which contains photo-hardening oligomers, reactive thinners as well as photo initiators, into a photo hardenable system and subsequent photo radiation under the exclusion of oxygen, a solvent to be evaporated can be completely dispensed with. Thus no (often toxic) solvent emissions are generated, and therefore the contamination of the work place is small without the costly use of additional safety measures. By means of the elimination of the drying process, which in the case of solvent-containing coating solution is very time-consuming or only makes coating of low thickness possible, the processing times can be greatly reduced. By a corresponding of the parameters (for example an increased addition of photo initiators) very short hardening times can be achieved. The process further distinguishes itself by the very simple processing methods as well as a low apparatus cost, and, furthermore, the hardened casting resin system has, in particular in contrast to thermotropic gels according to the state of the art, a clearly improved long-term stability.
During the hardening process, which takes place under the effect of photo radiation, in the present production process the reactive thinner becomes part of the hardening reaction (depending on the intensity of the radiation, the addition of corresponding photo initiators as well as the fill form of the casting resin system a duration of photo radiation of from 1 to 20 minutes is required). In this case the thermotropic compound or component turns out to be very finely distributed and is, therefore, added to the matrix in the crystalline state, as it generates itself. In order to make the desired precipitation possible, the matrix solution must display a corresponding solubility for the thermotropic component. In order to make possible the desired precipitation, the matrix solution must have a corresponding solubility for the thermotropic component. The solvent power of the matrix in combination with the cross-linking speed determines the grain size distribution as well as the number of separation zones, which in turn have a significant effect upon the radiation technological properties of the layers. Thus the temperature dependent as reduction of the degree of radiation transmission as well as the dependence of the wave length of the transmission can be varied purposefully by means of these parameters.
In any case, however, one has to see to it that the optical density of the matrix being generated is adjusted to the thermotropic component, i.e. that the index of refraction of the matrix corresponds to that of the thermotropic component below the temperature determining the structural change of the thermotropic component (for example, the index of refraction of the matrix is preferably 1.5<n
D
20
<1.58) when paraffins are used. In this context it is advantageous or required that the index of refraction of the matrix is across a wide temperature range (for example between 10 and 40 EC).
Because in order to harden the matrix solution no thermal treatment is necessary, the entire production process, which means the solution of the thermotropic monomer compound in the matrix solution as well as the subsequent photoradiation, can take place at room temperature. Because of reasons of processing technology an ambient temperature range of from 10 to 30 EC must be maintained, preferably 20 EC.
In this w
Bicer Taner
Goedeke Holger
Schwitalla Christoph
Fraunhoger-Gesellschaft zur Foerderung der Angewandten Forschung
Marshall & Melhorn LLC
McClendon Sanza L.
Seidleck James J.
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