Reflecting textile web and method for the production thereof

A reflecting flexible textile web is proposed comprising a textile support metal coated on at least one side and in the form of a woven fabric, knitted fabric, non-woven fabric or thread ply sewn fabric, the threads or fibres of which are coated with possibly flame-retarding modified transparent plastic, in which high reflectivity is achieved for infrared radiation but at the same time translucence or light in the visible region in that the metal coating takes place substantially only in the region of the intersections of the threads or fibres while the regions of the textile support disposed between the intersections are substantially free from metal coating and thus permeable to light. Furthermore, a method for making said textile web is proposed in which the textile support is firstly coated by immersion impregnation with a highly viscous plastic dispersion and metal is transferred in the transfer method from a metal-coated foil under elevated temperature and elevated temperature selectively to the raised regions of the plastic-coated textile support. The textile web can be used in particular for making sun roller blinds and insulating roller blinds.

FIELD OF THE INVENTION 
The invention relates to a reflecting flexible textile web of a textile 
support metal coated on at least one side and in the form of a woven 
fabric, knitted fabric, non-woven fabric or thread ply sewn fabric, whose 
threads or fibres are coated with possibly flame-retarding modified 
transparent plastic, and to a method for the production thereof. 
BACKGROUND OF THE INVENTION 
German Patent Application No. 3,135,271 discloses an 
infrared-radiation-reflecting flexible multilayer material web in which a 
support mesh is adhesively bonded on both sides to a textile support web 
and in which the two textile support webs are each provided on the outside 
with a metal coating and the metal coatings are provided with a further 
protective coating. This known material web is distinguished by high 
thermal reflection with simultaneous vapour permeability. The two metal 
coatings in the known material web, which is apparently to be used for 
making insulating blinds as employed in particular for roof windows, are 
formed as cohesive closed metal layers vapour deposited in vacuum and are 
therefore completely opaque to light in the visible range, i.e. in the 
wavelength range between 0.365 and 0.75 .mu.m. 
European Patent Publication No. 109,638 discloses a method of making 
metallized textile sheet structures in which the textile properties of the 
support are retained in that a metal layer applied to the textile material 
by either an electroless, wet chemical or vapour deposition method is 
subsequently thickened by electroplating. The metallized textile web made 
in this manner has because of its high electrical and thermal conductivity 
a good heat stability and high reflectivity for incident electromagnetic 
radiation; it is therefore suitable for example for making flexible screen 
antennas for radar waves but can also be used in all cases where the 
carrying away of electrostatic charges or the screening of high-frequency 
electromagnetic waves is important. These metal layers deposited in 
electroless manner or electrolytically and thickened by electroplating are 
also completely impermeable to light in the visible range. 
DE No. 3,016,191 discloses a non-inflammable sun protection blind 
comprising a textile support in the form of a woven fabric, knitted 
fabric, non-woven fabric or a thread ply sewn fabric whose threads or 
fibres are impregnated with two different layers of flexible halogen-free 
plastic, that is a duroplastic and a thermoplastic plastic layer, both 
plastic layers containing a halogen-free flame-retarding agent. This known 
sun protection blind is not metal coated; it is thus permeable both to 
light in the visible range and to radiation of longer wavelength in the 
near infrared range (0.75-3 .mu.m). 
Furthermore, various insulating blinds or insulating blind materials are on 
the market which in particular are used to keep off excessive solar 
radiation for roof windows and which are made by laminating a relatively 
thick aluminium foil to a textile material, the bonding being obtained by 
an adhesive layer between the metal foil and the textile material. These 
relatively stiff insulating blinds are also completely impermeable to 
light in the visible range. It is an object of this invention to provide a 
metal-coated flexible textile web which has a high reflectivity for 
infrared radiation in the near IR range between about 0.75 and 3 .mu.m but 
at the same time has good transmission and translucence properties for 
light in the visible range between 0.365 and 0.75 .mu.m and in spite of 
the metal coating on at least one side retains its textile appearance and 
its textile nature. A further object of the invention is to provide a 
method for producing such a textile web. 
Thus, this invention provides a textile web of the type mentioned at the 
beginning in that the metal coating is disposed substantially only in the 
region of the intersections of the threads or fibres of the textile 
support whilst the regions of the textile support disposed between the 
intersections are substantially free from the metal coating and thus 
permeable to light.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
It has surprisingly been found that the reflectivity for infrared radiation 
in the wavelength region between 0.75 and 3 .mu.m with the textile web 
according to the invention in which only the raised regions of the textile 
support are coated with the reflecting metal is only insignificantly less 
than the reflectivity for the same wavelength range of a textile web 
coated over its entire surface with metal. The term "raised regions" means 
in a fabric the intersection points between warp and weft threads which 
lie outside the plane of the warped threads and outside the plane of the 
weft threads; in a mesh fabric (knitted fabric, hosiery) the raised 
regions are those at which the stitch elements of adjacent stitch rows and 
stitch wales intersect, whereas in the case of tangled fibre non-woven 
fabrics and thread ply sewn fabrics they are the regions at which more 
threads or fibres intersect than intersect on an average at the thinner 
areas of these non-woven fabrics. Although the reflectivity of the textile 
web according to the invention is only slightly less in the wavelength of 
the near infrared range decisive for thermal protection purposes than with 
textile webs metal coated over the entire area, the reflecting textile web 
according to the invention has a high translucence for light in the 
visible range. A sun blind made from the textile web according to the 
invention thus does not lead to complete darkening of the room equipped 
therewith but like a textile curtain or curtain netting allows adequate 
light to pass in the visible range and this leads to a pleasant weakening 
of the sunlight but not to complete darkening. On the other hand, the 
incident thermal radiation is largely reflected and hardly absorbed. 
If the textile web according to the invention is provided with a metal 
coating only on one side the purely textile appearance of the 
non-metallized back of the textile support is completely retained. 
An advantageous embodiment of the textile web according to the invention 
resides in that a bonding plastic layer is disposed at least at the 
metal-coated areas of the web between the plastic-coated textile support 
and the metal coating. This improves the bonding of the metal particles to 
the textile support which is particularly important when the textile web 
is used for making roller blinds. For on unrolling and rolling up of the 
blind the coating is subjected to a high mechanical stress so that in the 
course of time the metal particles peel off if no additional bonding 
plastic layer is used. 
Preferably, as textile support a textured fabric is used, for example a 
fabric in which the weft yarn is more voluminous and heavier than the warp 
yarn, or a fabric which is made from crimped yarns or yarns textured in 
other known manner. These fabrics with relief-like surface have 
particularly pronounced raised and lower regions which facilitates the 
selective metal coating only in the raised regions of the intersections of 
the threads or fibres of the textile web. 
In a further advantageous embodiment of the textile web according to the 
invention the textile support is coated with a mixture of thermoplastic 
and thermosetting (duroplastic) plastic, preferably of acrylate copolymers 
which possibly additionally contain an ethylene-vinyl acetate copolymer. 
It has been found that the choice of such a specific plastic mixture 
particularly facilitates the selective more or less punctiform metal 
coating. 
In a further advantageous embodiment of the textile web according to the 
invention the metal coating is coated in a manner known per se with a thin 
layer of a transparent protective lacquer and thereby additionally 
protected from abrasion, damage and wear. 
The textile web according to the invention preferably has a diffused 
reflection of 60-90% of the light and thermal radiation, incident on the 
metal-coated side, of the near infrared range with wavelengths between 0.7 
and 2.5 .mu.m. 
The method of making the textile web according to the invention is 
characterized by the combination of the following features: 
(a) a possibly non-inflammatory finished textile support in the form of a 
woven fabric, knitted fabric, non-woven fabric or thread ply sewn fabric 
is thermofixed and thereafter 
(b) coated with a highly viscous dispersion of a mixture of thermoplastic 
and thermosetting (duroplastic) transparent plastic in a suitable solvent 
by immersion impregnation, whereupon 
(c) excess coating composition is doctored off on both sides, whereafter 
the support thus coated 
(d) is dried in a drying passage; 
(e) the plastic-coated and dried support and a metal-vapour-coated foil or 
sheet are preheated simultaneously but separately from each other and 
thereafter 
(f) brought together in such a manner that the metal-coated side of the 
foil contacts at least one side of the plastic-coated support, and 
(g) hot pressed with the aid of laminating rolls at elevated pressure, 
whereafter 
(h) the laminate is cooled to about room temperature and 
(i) the foil is peeled off again. 
Preferably, for the immersion impregnation a plastic dispersion having a 
viscosity of 1.5 to 3.0 Pa.multidot.s, preferably 1.8 to 2.5 Pa.multidot.s 
is used. The area weight of the coating composition applied by immersion 
impregnation is preferably 60 to 120 g/m.sup.2. 
It has been found particularly advantageous to use for the immersion 
impregnation an aqueous dispersion of 50 to 60 parts by weight of a 
thermoplastic acrylate copolymer, 40 to 50 parts by weight of one or more 
self-crosslinking duroplastic acrylate homo or copolymers and 0 to 20 
parts by weight ethylene-vinyl acetate copolymer. The choice of this 
specific plastic mixture leads to high selectivity of the bonding of the 
metal particles in the region of the raised areas, i.e. the thread 
intersections of the textile support. 
If desired, for the immersion impregnation a dispersion may be used which 
contains in a manner known per se additionally a flame-protection agent 
and/or biocides. When for example the textile web according to the 
invention is used in public buildings such as schools, hospitals, theatres 
or particularly fire-endangered premises such as hotels, restaurants, 
discotheques or also in motor vehicles and aircraft, not only is it 
convenient to use a textile support finished in non-inflammable or 
flame-retarding manner from the start but in addition to employ for the 
coating as well a plastic dispersion containing a flame-protection agent. 
If on the other hand the textile web according to the invention is to be 
used in wet rooms or for interior decorating of ships then it is 
convenient to add to the plastic dispersion a biocide. 
For cost reasons the textile support will generally be made from the usual 
combustible textile fibres of natural or synthetic origin but can be 
produced alternatively from non-inflammable fibres, for example glass 
fibres, ceramic fibres, metal fibres, carbon and aramide fibres. 
The doctoring off on both sides of the excess coating composition is 
preferably carried out by means of an air doctoring system having two 
offset blades but other conventional doctor blades can also be used; the 
important point is only that the doctoring off is carried out 
fundamentally from both sides of the coated textile support in order to 
prevent on one of the two sides the depressions lying between the raised 
regions of the textile material from being filled with plastic composition 
and thus evened. 
The foil coated with vapour deposited metal is preferably a polyester foil 
with aluminium, gold or copper vapour deposited thereon. The polyester 
foil serves only as auxiliary sheet or intermediate carrier for the metal 
layer. To achieve special esthetic effects the metal vapour deposited onto 
the foil may also be lacquered in a manner known per se. 
A decisive advantage of the method according to the invention resides 
fundamentally in that the metal is transferred from an auxiliary foil to 
the plastic-coated textile support using pressure and heat, i.e. it is not 
necessary to vapour deposit metal on the entire laminate in a high vacuum. 
Admittedly, the auxiliary foil obtainable as such commercially must also 
be vapour coated with the metal but with the far simpler structure of the 
polyester foil this can be done very much more easily and thus more 
cheaply. 
Preferably, a foil is used of the type comprising between the support foil 
of polyester and the vapour deposited metal layer a parting agent layer 
because then the support foil after transfer of the metal to the 
plastic-coated textile web can be more easily peeled off the laminate 
again without the transferred metal particles being pulled off the textile 
web. 
Further, preferably a metal transfer foil is used of the type in which the 
vapour deposited metal layer is additionally covered with a bonding 
plastic layer. For the bond between the metal particles and the 
plastic-coated textile web is improved by the bonding plastic layer. This 
bonding plastic layer consists preferably of ethylene-vinyl acetate 
copolymer. 
The metal transfer carried out with the aid of laminating rolls from the 
metal-coated foil to the plastic-coated textile web is preferably done 
under a pressure of 4.10.sup.5 -6.10.sup.5 Pa and at a temperature of 
about 110.degree.-140.degree. C. 
Particularly advantageous is the use of the textile web according to the 
invention for making sun blinds, camouflage nets or camouflage tarpaulins, 
insulating roller blinds, insulating wallpapers, working clothing and the 
inner linings of motor vehicles and aircraft. In addition, the textile web 
according to the invention may be used quite generally in the motor 
vehicle field, in medical technology, building, both for interior fittings 
and on the outside of high buildings, gardening, for example for sun 
blinds in greenhouses, and in all cases where it is important to keep 
long-wave electromagnetic radiation, in particular thermal radiation, away 
from people, machines, apparatus, structures or surfaces. 
Whereas the reflection of the radiation in the near infrared range can 
reach up to 90% of the incident radiation, the transmission in this 
wavelength range can be 10-50% with the textile web according to the 
invention. 
The appearance of the textile web according to the invention may be varied 
in almost any desirable manner by using coloured textile supports and 
pigmented coating compositions, the translucence of the textile web being 
retained in every case, although account must be taken of the fact that 
with dark colouring of the textile support and/or the coating composition 
a higher thermal absorption by the textile web itself is unavoidable. 
Consequently, the use of unpigmented coating compositions and undyed or at 
least brightly dyed textile supports is preferred.