Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,...
Reexamination Certificate
2002-10-10
2004-07-27
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
C428S403000, C428S699000, C428S701000, C428S702000, C106S415000, C106S436000, C106S439000, C106S453000, C106S454000, C106S456000, C106S480000
Reexamination Certificate
active
06767633
ABSTRACT:
The invention relates to the use of multilayer pigments in transparent media which are distinguished by the fact that they have angle-selective transmission or reflection properties and/or absorption properties.
The sun is an inexhaustible, environmentally friendly energy source which provides us with potential energy for heating buildings. Overall, four times as much energy is radiated onto a building as is consumed in heating energy inside.
Transparent thermal insulation (TTI) is a technology for solar room heating. The materials involved here combine low thermal conductivity with a high degree of transmission for solar radiation. In the case of an outside wall with transparent thermal insulation, a TTI element is located in front of a solid wall to which a black or coloured absorber layer has been applied. The incident solar energy is guided by this system from the outside of a building wall through a glass tube system, hits the wall formers and is converted into heat. Although the TTI systems employed at present give good thermal insulation and also energy recovery in winter, the way they function means that they result in overheating of the wall in summer and in unpleasant inside wall temperatures if mechanical shading systems, such as, for example, roller blinds, venetian blinds, slats, extractors, etc., are not available. In addition, the black absorber layers necessary for absorption of the energy represent a decorative restriction in the design of building walls.
Through application of transparent thermal-insulation modules to south-facing walls, solar energy can be introduced into a building to an increased extent and utilized for heating. This effect is very welcome in winter, but in summer additionally introduced heat results in overheating of the building.
The solar radiation hitting a building wall changes its angle of incidence depending on the time of day and on the season (winter/summer). In winter, the angle of incidence onto a south-facing wall with the sun at its highest point (12.00 hours) is about 12°, while in summer it is about 68° in Germany (depending on the latitude).
DE-A-195 01 114 discloses a process which includes the direct and diffuse solar radiation present in winter into the heat balance of a house in a positive manner by simple measures. The prior art describes a paint which reflects in the visible region of the electromagnetic spectrum and can be rendred absorbent in the near infrared region with the aid of a pigment mixture. In contrast to the present invention, only the solar radiation present in winter has a positive effect on the heat balance of a house in DE-A-195 01 114. However, it is disadvantageous here that the much more intense solar radiation in spring, summer and autumn can result in over-heating of the house, which can only be countered by ventilation.
The pigmented transparent medium disclosed in DE 197 56 037 A1 has solved this problem by not only utilizing the solar radiation in winter, but also protecting buildings against overheating in summer. To this end, overheating of buildings and rooms is prevented using pigments with angle-selective transmission, such as, for example, pearlescent pigments. The solar radiation in the wavelength range 0.25-2.5 &mgr;m is transmitted by a pigmented area to a lesser extent in summer with the sun high in the sky than in the winter months with the sun low. The transmission properties of the pearlescent pigments are determined by the refractive index and absorption properties of the coating materials, the layer thicknesses and the layer-sequence.
The object of the present invention is to significantly increase the efficiency of angle-selective shading of the TTI.
Multilayer pigments are not only of interest due to their colouring properties, but also are increasingly being used in functional areas. Multilayer pigments exhibit selective reflection or transmission in the visible wavelength range, properties which are responsible for the colour impression. This wavelength-dependent reflection or transmission can be extended to the near infrared region and is partially utilized in agricultural sheeting. On the other hand, multilayer pigments exhibit different reflection or transmission and absorption depending on the angle of incidence of the incident radiation. A completely new functional area of application for multilayer pigments should thus be found in the construction sector in the design of building walls.
The angle dependence of the optical properties can be increased through a suitable choice and combination of coating materials of different refractive index. The wavelengths of maximum transmission of the pigments and maximum solar energy ideally coincide in the case of perpendicular solar radiation, while the maxima are shifted significantly with respect to one another in the case of flat incidence, i.e. for angles greater than 60° from the perpendicular. The ratio between the degrees of transmission at angles of incidence of 0° and 60° can thus be reduced from 0.6 for conventional pearlescent pigments to 0.1 for ideal multilayer pigments.
Surprisingly, it has been found that on use of multilayer pigments, a considerably greater shading effect can be achieved than in the case of conventional pearlescent pigments. Through a suitable combination of a plurality of layers, the angle-dependent transmission behaviour of the pigments can be reinforced and matched to the requirements of the particular building wall. The use of multilayer pigments enables the ratio between solar transmission in winter and summer to be reduced from 0.5-0.85 for conventional pearlescent pigments to 0.1-0.6 for multilayer pigments.
On corresponding application of these multilayer pigments to a building wall, transmission of solar radiation, i.e. warming of the building wall, can be achieved in winter, while reflection/absorption of the solar radiation, i.e. shading of the building wall, can be achieved in summer.
The invention thus relates to transparent media comprising multilayer pigments based on platelet-form substrates having angle-selective reflection or transmission properties and/or absorption properties, characterised in that the ratio between the degree of solar transmission in summer (angle of incidence of the solar radiation from 55 to 70°) and the degree of solar transmission in winter (angle of incidence of the solar radiation from 5 to 20°) is in the range 0.1-0.6.
The angle-selective properties of the multilayer pigments in the transparent media are concentrated on the spectral region of solar radiation, i.e. from 0.25 to 2.5 &mgr;m. In this wavelength range, the directed hemispherical degree of transmission and reflection can be measured, for example on glass substrates to which the functional pigments have been applied. From these measured directed hemispherical degrees of transmission and reflection, solar or visual degrees of transmission and reflection can be calculated in accordance with DIN 67507 by weighting with the solar spectrum or the brightness sensitivity of the human eye.
All multilayer pigments known to the person skilled in the art which have angle-selective reflection or transmission properties and absorption properties and whose ratio between the degree of solar transmission in summer (angle of incidence of the solar radiation from 55 to 70°) and the degree of solar transmission in winter (angle of incidence of the solar radiation from 5 to 20°) is in the range from 0.1 to 0.6, preferably less than 0.5, in particular from 0.3 to 0.5, are suitable in the present invention.
In order to support the angle-selective transmission or reflection properties and/or absorption properties of the functional multilayer pigments, it is advisable to apply the platelet-form pigments to a structured substrate or to incorporate them into a structure-forming medium, which in turn specify the orientation of the platelets. Given appropriate alignment of the pigment platelets, the angle-selective effect is reinforced effectively. The structuring can be achieved, for example, by applying the pigmented
Brabänder Carsten
Brückner Hans-Dieter
Hechler Wolfgang
Pfaff Gerhard
Reynders Peter
Blackwell-Rudasill G.
Jones Deborah
Merck Patent GmbH
Millen White Zelano & Branigan P.C.
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