Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-06-04
2001-02-27
Yoon, Tae (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S205000, C524S401000, C524S403000, C524S406000, C524S408000, C524S413000, C524S418000, C524S439000, C524S440000, C524S441000, C524S496000
Reexamination Certificate
active
06194484
ABSTRACT:
It would be desirable to save energy in houses and buildings if the coating materials in the exterior and/or interior could absorb solar energy without emitting this again directly in the long-wave range of the thermal infrared.
Normally, white coating materials employed as wall paints have the following spectral properties:
The reflection in the wavelength range of visible light from 0.35 to 0.7 is over 80%. The absorption in the wavelength range of the near infrared from 0.7 to 2.5 &mgr;m increases by 10% at 0.7 &mgr;m to approximately 50% at 2.5 &mgr;m. The emission in the wavelength range of the thermal infrared from 8 to 14 &mgr;m typically lies on the average at 90%.
However, since solar irradiation has its maximal energy at approximately 1 &mgr;m, it would be desirable to achieve an absorption which is as high as possible with coating material starting from 0.7 &mgr;m, i.e. directly adjacent to the visible range. In this, the sun provides 7-fold more energy in the short-wave half of the near infrared as in the long-wave half. Furthermore, it is desirable to not re-emit absorbed energy in the long-wave range of the thermal infrared at 8 to 14 &mgr;m.
In DE-A 195 01 114, coating materials are disclosed which only partially re-emit absorbed solar energy in the long-wave range of thermal radiation. However, the particles introduced here for absorption of the solar energy lead to a more or less strong darkening of the coating material in the visible range.
Dark, absorbing coating materials which can take up the largest part of solar energy do not correspond to the aesthetic needs of house inhabitants. White or at least near white, very light coating materials are desired.
DE-A 195 01 114 discloses a coating material of this type which can have a relatively light appearance but has a very low degree of effectiveness with respect to solar absorption.
Furthermore, it is desirable that house walls in temperate to cold climatic zones have an angle-dependent degree of emission which permits less energy from being radiated off into the cold sky but receive the thermal radiation of the predominantly warm ground. In contrast, in hot climatic zones it is desirable to select a degree of emission directed to the sky which is as large as possible because heat can be led off into the predominantly clear sky in desert regions, whereas the thermal irradiation of the hot surroundings is reflected.
In DE-A 195 01 114 an angle-dependent degree of emission is not provided for a coating.
The object of the invention is to provide a white, preferably light, coating material having a high absorption capacity for solar radiation and having a low emission capacity in the range of the thermal infrared from 5 to 100 &mgr;m, but at least from 8 to 14 &mgr;m. A light tinting means that the reflection of the visible light in the wavelength range 0.35 to 0.7 &mgr;m takes on values of 50% and more.
With the coating material proposed according to the invention, it is possible to absorb 30 to 50% of the solar energy with a coating material which is preferably light for aesthetic reasons. This is clearly more than is possible with customary light coating materials. Additionally, the energy obtained in this manner is only re-emitted to approximately 50% in the wavelength range of the thermal infrared. The energy gain can be led into the house wall. With customary coating materials, the degree of emission in the wavelength range of the thermal infrared lies at 90 to 95%. Here, only small energy gains are possible because the absorbed solar energy is re-emitted at 90 to 95%.
The object is solved according to the invention by a coating material which comprises,
a) a binding agent with large transparency of at least 30%, preferably >50%, in the range of visible light from 0.35 to 0.7 &mgr;m and with at least 20%, preferably >40%, in the range of the thermal infrared from 5 to 100 &mgr;m, at least from 5 to 15 &mgr;m,
b) first, plate-shaped particles which reflect in the wavelength range of the thermal infrared from 5 to 100 &mgr;m, but at least from 5 to 25 &mgr;m, and whose dimensions are L×B×T, L=5-100 &mgr;m, B=5-100 &mgr;m and T=0.1-5 &mgr;m, preferably L=30-60 &mgr;m, B=30-60 &mgr;m and T=0.5-1,5 &mgr;m, whereby L=length, B=breadth, and T=thickness.
and/or first, spherical particles which backscatter (Mie backscattering) in the wavelength range of thermal infrared from 5 to 100 &mgr;m, but at least from 5 to 25 &mgr;m, and have a degree of transmission in this wavelength range of at least 20% and are present as monocrystals, wherein the average diameter of the first, spherical particles d is determined by the formula
d
=10 &mgr;m/2.1·(n
T10
−n
B10
),
wherein
n
T10
=refractive index of the first, spherical particle at the wavelength 10 &mgr;m and
n
B10
=refractive index of the binding agent at the wavelength 10 &mgr;m
and/or second, spherical particles which have and/or form a hollow space in the dry state that are comprised of a material that has a degree of transmission in the range of the thermal infrared from 5 to 100 &mgr;m, but at least from 5 to 25 &mgr;m, of >20%, preferably >30%, and backscatter and/or reflect in the wavelength range of the thermal infrared from 5 to 100 &mgr;m, but at least from 5 to 25 &mgr;m, and whose average diameter is 2 to 20 &mgr;m
c) second particles which reflect and/or backscatter in the wavelength range of visible light from 0.35 to 0.7 &mgr;m and have a degree of transmission in the wavelength range of the thermal infrared from 5 to 100 &mgr;m, but at least from 5 to 25 &mgr;m, of >20%, preferably >40%, and which are present at monocrystals, wherein the average diameter of the second particle d is determined by the formula
d
=0.55 &mgr;m/2.1·(n
T0.55
−n
B0.55
),
wherein
n
T0.55
=refractive index of the second particle at the wavelength 0.55 &mgr;m and
n
B0.55
=refractive index of the binding agent at the wavelength 0.55 &mgr;m
and/or polymer pigments which have a degree of transmission in the thermal infrared range of 5 to 100 &mgr;m, but at least from 8 to 14 &mgr;m, of >20%, preferably >30%, and which have and/or form a hollow space in the dry state, wherein the average diameter of the polymer pigment particles is 0.2 to 2 &mgr;m, preferably 0.3 to 1 &mgr;m
d) third, spherical particles which are electrically conducting and have a low absorption in the range of the thermal infrared from 5 to 25 &mgr;m of <80%, preferably <60%, and whose average diameter is 0.1 to 2 &mgr;m, preferably 0.2 to 1 &mgr;m
e) other known additives which are typically used in coatings, namely solvents such as water, aromatic solvents such as solvent naphtha, xylene, toluene, polar solvents such as alcohols and thickening agents, thixotroping agents, anti-foaming agents, dispersing agents for the given particles, additives for reducing the film-forming temperature such as glycols and benzene.
Average diameter or average particle size is to be understood in that the diameter for the particle size take on values in the respectively named ranges and are present in a normal distribution around this value.
Advantageous embodiments of the subject matter of the invention are provided for in the dependent claims.
An advantageous embodiment of the subject matter of the invention is characterized in that the binding agent is selected from
a) the group of aqueous dispersions and emulsions which comprise dispersions and emulsions based on acrylate, styrene acrylate, polyethylene, polyethylene oxidate, ethylene-acrylic acid copolymers, methacrylate, vinylpyrrolidone-vinyl acetate copolymers, polyvinylpyrrolidone, polyisopropyl acrylate, polyurethane and/or
b) from the group of solvent-containing binding agents which comprise acryl, cyclized rubber, butyl rubber, hydrocarbon resin, &agr;-methylstyrene-acrylonitrile copolymers, polyester imide, acryl acid butyl esters, polyacrylic acid esters, polyurethanes, aliphatic polyurethanes, chlorosul
Fitch Even Tabin & Flannery
Yoon Tae
LandOfFree
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