Bright metalized fabric and method of producing such a fabric

A bright-finish metal-coated fabric having a metal layer directly deposited on the fabric. A fabric, selected to be capable of flattening or polishing under heat and pressure, is pressed against a heated surface and is then vacuum metalized. In a preferred embodiment, a thermoplastic fabric is flattened against a hot roll in a calender press under high pressure, and aluminum is then vapor-deposited.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to fabrics having a bright-finish metallic 
appearance, and more particularly to thermoplastic fabrics which are 
desired to have a brilliant metallic reflectance either for aesthetic 
reasons or for heat reflecting. 
For thousands of years highly reflecting fabrics have been prized for 
special applications, even to the point where precious metals such as gold 
were incorporated in the weave. Those who could not afford such 
extravagance would get satin or, in modern times, synthetic fabrics which 
were specially treated to provide a glossy appearance. Where heat 
reflectance is a major consideration, aluminized fabrics have been made at 
great expense for protective clothing such as used for firemen or workers 
around furnaces, but these were not suitable for ordinary use. 
In addition to fabrics used for clothing, the great interest in energy 
conservation over the last few years has sparked development of methods 
for reducing winter heat loss and summer heat gain through windows. 
Commercial buildings often have heat-reflecting films applied to windows, 
but these have not found wide application in private homes because of the 
nuisance in having them applied, the loss in visible light transmission 
which makes a slightly cloudy day seem gloomy, and the fact that the 
windows can have a mirror-like appearance which is always there. One 
solution to this dilemma is the reflecting window shade, which has a 
metalized film on an outside layer, and a fabric inside surface for 
appearance and perhaps also for insulation. However, these multi-layer 
shades are bulky, and tend not to hang flat because of the different 
characteristics of the film and the fabric. 
2. Description of the Prior Art 
Vapor deposition of metal onto a transparent film to produce an article 
suitable for gluing onto a window has been known at least since U.S. Pat. 
No. 3,290,203. Although the products taught therein successfully reduced 
heat loss, and could be tinted to provide a pleasing appearance, they 
could only be permanently installed (the film could be removed but not 
re-applied). Thus these products could not be used as a window shade, 
which could be rolled up as desired. More recently, metalized polyester 
film shades have become commercially available. 
Although metalizing of film has been practiced successfully for many years, 
the problems involved in metalizing other materials have been solved only 
more slowly, and often less successfully, as pointed out in the article, 
"Metalizing--What it is, What it does--It's Dramatic, Efficient", 
published in "Paper, Film and Foil Converter", February, 1958, pp 26-29. 
Up to now, the most successful commercial process for making glossy 
metalized fabrics has been the transfer process, by which a metal film is 
actually glued to fabric. This process involves preparing a transfer film 
by applying a "release agent" to a base or carrier film such as a 
polyester film. A thin film of the desired metal is then vapor-deposited 
on the release agent. A thin layer of adhesive is then applied over the 
metal layer. Another adhesive layer is applied to the fabric, and the 
metal layer is then transferred to the fabric by placing the 
adhesive-coated metal side of the film in contact with the adhesive-coated 
fabric, and passing them around a heated drum while holding the film 
against the fabric, for example by an endless blanket pulled taut around 
the outside of the sandwich. Although successful, this process is quite 
expensive, because of the cost of the carrier film, application of its 
multiple layers in successively different machines, and then finally the 
transfer process; in 1981 this procedure added more than $3.00 peryard to 
the cost of a fabric. 
Attempts to apply metal layers to fabric directly did not produce the 
desired glossy appearance. Experiments with many different fabrics, 
including "long float" fabrics which had a glossier than average 
appearance before coating because of the special weave, as well as "bright 
yarn" fabrics of different chemical compositions, have so far been 
unsuccessful in producing a really high shine. 
SUMMARY OF THE INVENTION 
To overcome the disadvantages of the prior art, it is an object of the 
invention to provide a method of producing a glossy metalized fabric which 
does not require special weaving or knitting of the fabric. 
Another object of the invention is to provide a bright-finish metalized 
fabric in which the metal is applied directly to the cloth. 
Yet another object of the invention is to provide a method by which a 
sculptured metalized appearance may be obtained without any additional 
processing. 
According to a first aspect of the invention, I have discovered that a 
bright-metallic-finish fabric is produced by selecting a thermoplastic 
fabric, flattening a surface of the fabric by pressing it against a smooth 
heated surface, and then depositing a reflective metal material on the 
flattened surface. More particularly, as used herein, flattening means a 
process step in which a fabric is compressed against a surface under such 
pressure and temperature conditions that the apparent thickness and 
porosity (permeability to air) of the fabric is reduced. 
In a preferred embodiment of this aspect of the invention, flattening is 
performed by passing the thermoplastic fabric between two rolls, one of 
which has a polished surface and is heated to a temperature sufficient at 
least slightly to soften the surface of the fabric; in particular, the 
flattening step involves passing the fabric through the nip of a 
calendering press under high pressure. After flattening, the fabric is 
placed in a vacuum chamber, and a thin coating of a desired metal is 
vapor-deposited on at least the surface which contacted the heated 
polished roll. To produce a high reflectance silvery surface 
inexpensively, deposition of an aluminum layer having a resistance of less 
than one ohm per square is preferred. 
In order to improve the resistance of the bright finish to laundry or 
dry-cleaning effects, after flattening and metalizing, a clear polymer top 
coating may be applied. Polyurethane materials have been found 
particularly suitable for this purpose. While applicant is familiar with 
the use of such coatings on foil materials, to the best of his knowledge 
transparent colored coatings have not been previously applied to fabrics. 
Because the bright finish of this invention is useful in items such as 
sleeping bags where the surface is subject to considerable friction 
against a user or user's clothing, the abrasion resistance gained is also 
quite valuable. 
Further, a gold or other color desirable for high fashion may be obtained, 
with no significant loss of brightness, by incorporating a transparent 
dyestuff in a urethane material which is applied using a solvent system 
and is then cured. By selecting a "neutral" dyestuff, and selected solids 
contents for the system, the resultant product is not attacked 
significantly by chlorinated solvents such as perchlorethylene used in 
drycleaning. 
According to a further preferred method embodying the invention, the heated 
roll has a mirror-like chromed surface, and may also be engraved with fine 
lines arranged at an acute angle, prefereably approximately 
20.degree.,from the direction of the filling or horizontal of the fabric; 
and if the fabric is composed of twisted yarns, the engraved lines are in 
the direction of yarn twist. 
According to a second aspect of the invention, a high-metallic glossy 
patterned fabric is produced by selecting a thermoplastic fabric; 
pattern-flattening a surface of the fabric by passing the fabric between 
two rolls of a calendering press under high pressure, one of these rolls 
being heated and having a mirror-like surface in which a decorative 
pattern is engraved or recesed, such that the engraved or recessed areas 
flatten the fabric less than the non-recessed areas, or not at all; and 
then depositing a reflective metal material on the surface which contacted 
the heated and patterned roll, so as to produce a fabric having a high 
gloss pattern against a background of lesser or little or no gloss, 
without any additional processing steps. 
According to yet a third aspect of the invention, a bright-metallic-finish 
fabric may be produced by selecting a fabric comprising thermoplastic 
yarns, polishing a surface of the fabric by pressing it against a heated 
surface with relative motion between the fabric surface and the heated 
surface, and then depositing a reflective metal material on the polished 
surface. In a preferred embodiment of this aspect of the invention, the 
fabric is polished by passing it around at least one roll such as a heated 
roll or drying can, the roll being rotated with a surface speed faster or 
slower than the fabric speed or in the reverse direction. 
By use of the inventive method, a fabric is produced which has an 
exceptionally high metallic gloss, is far denser (less porous) than the 
untreated fabric, and yet has a good "hand" and retains its appearance 
after ordinary laundering or dry cleaning. The flattening and depositing 
steps (with aluminum) would typically add only $0.15 to $1.40 per yard to 
the cost of the fabric, at 1981 prices, depending on the fabric type and 
length processed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
According to a first preferred embodiment of the invention according to its 
first aspect, a fabric is selected consisting of thermoplastic twisted 
yarns such as a polyester, having a moderately dense weave. The fabric is 
then flattened by calendering it in a press having a chromed, polished 
roll heated to a temperature of at least approximately 385.degree. F. 
(197.degree. C.), and preferably to a temperature of approximattely 
425.degree. F. (218.degree. C.). Opposite the heated roll is an unheated 
second roll, such as a paper roll; that is, one formed of compressed discs 
of heat-resistant paper and having a very smooth surface. The rolls are 
pressed together with a force of at least approximately 21/2 tons per foot 
of roll length (150,000 newtons per meter), and preferably with a force of 
approximately 10 tons per foot (300,000 newtons per meter). The fabric is 
passed through the nip of the press at a speed of approximately 15 yards 
per minute (14 meters per minute). 
After calendering, the fabric is wound on a roll. The roll is then placed 
into a vacuum chamber, and a high vacuum is pulled to out-gas the fabric. 
The fabric is then passed through a space in the chamber to a take-up 
roll, as it does so a layer of aluminum being vapor-deposited on at least 
the surface of the fabric which had contacted the chromed, heated roll. 
For maximum reflectance if aluminum is deposited, a thickness of at least 
500 to 800 .ANG. is applied. Upon removal from the chamber, the fabric 
will be observed to have a high silver gloss on that surface. 
According to a second preferred embodiment of the invention, a fabric 
selected as above is flattened by calendering at the same temperature and 
pressure; however, instead of a smooth polished chromed roll, the steel 
roll is engraved with a series of fine lines, between 150 and 500 lines 
per inch (6 to 20 lines per mm), generally at a 20.degree. angle to the 
filling or horizontal of the fabric in the direction of the twist of the 
yarn. 
In a further embodiment of the second aspect of the invention, the steel 
roll of a calendering press is engraved or otherwise provided with a 
decorative or other relief pattern, such that the recessed areas of the 
roll will provide less flattening. This roll is then heated, for example 
as described above, and a thermoplastic fabric is calendered under a high 
pressure determined to give the desired effect. After calendering, the 
fabric is coated with a vapor-deposited layer of metal, which will exhibit 
a high shine in the more heavily flattened areas but lesser gloss in the 
portions corresponding to the recessed areas of the roll. One should then 
expect a visual effect, after metalizing, somewhat like a damask. 
In yet another embodiment, of the third aspect of the invention, a fabric 
which includes thermoplastic yarns may have a surface polished by pressing 
it against a heated surface which undergoes relative motion with respect 
to the fabric. One or two or more passes around drying cans, appropriately 
heated, may so polish and flatten the surface contacting the can that 
metalizing as described under the other embodiments will provide a high 
gloss. The cans may be stationary, or rotated in either direction, so long 
as there is relative motion. 
EXAMPLE 
A 100% polyester fabric, woven with 70 denier warp and 150 denier filling, 
was selected for processing according to the first preferred method. The 
fabric was calendered using a polished, chromed steel roll heated to 
approximately 425.degree. F. (218.degree. C.). The polished steel first, 
or top, roll was approximately 14"(351/2) in diameter, while the bottom or 
second paper roll was 36" (81/2) inches in nominal diameter. The pressure 
on the calender was set at approximately 40 tons (1.2.times.10.sup.6 
newtons), which resulted in a force per unit length of about 10 tons per 
foot (300,000 newtons per meter). The calender was operated at about 15 
yards (13.6 meters) per minute. After calendering, a portion of the fabric 
was saved for testing, while the balance was vapor-deposited with 
aluminum, the coatig being thick enough to achieve a resistance of less 
than one ohm per square. The resulting fabric had a high, attractive 
silvery gloss on the surface which had contacted the steel roll, and a 
dull silver appearance on the reverse side. 
A sample of the fabric, which was neither calendered nor metalized, was 
measured and a thickness reading of 0.004 to 0.0044 inches, by micrometer, 
was obtained. The calendered, un-metalized portion was similarly measured, 
and read 0.0028 to 0.0033 inches, while the metalized portion read 0.003 
to 0.0035 inches. These readings should be considered only exemplary, of 
course, and may reflect significant measurement imperfection; nonetheless, 
they are believed to show significant flattening related to the high shine 
obtained. The differences between the calendered portion, and that fully 
metalized, is believed to be due to experimental error and random 
variation between different fabric areas, rather than to the metalizing. 
When viewed under a fluorescent light at an angle, through a 7-power loupe, 
the uncalendered, unmetalized sample showed reflection from highlights on 
the fill yarns, but almost none from the warp, when the fabric was turned 
so that the filling ran from the observer toward the light. Turned the 
same way, the calendered, unmetalized portion showed highlight reflections 
from both the filling and the warp. The metalized surface, on the side 
contacted by the heated roll, had a brilliant silver reflection from both 
filling and warp when viewed in the same light at the same angle. 
The difference in fabric permeability to airflow was also tested, following 
the method of ASTM D-737. The control sample (neither calendered nor 
metalized) showed an air flow of 221.7 cfm/ft.sup.2, with a range of 207.0 
to 232.0; while the calendered and metalized fabric showed an air flow of 
only 43.0 cfm/ft.sup.2, with a range of 41.0 to 51.0. These results 
demonstrate a great reduction of porosity, by use of the invention. 
To determine the effectiveness of the inventive fabric as a thermal shade 
or curtain, the reduction in thermal transmittance when compared with a 
bare window was measured by the Guarded Test Window Method, using a single 
light window, with the fabric sealed to the test window frame on all edges 
and the metalized surface facing the apparatus, in a manner to give the 
highest possible reading in terms of R value. With outside glass 
temperatures approximately the same, and inside ambient temperatures also 
about the same but approximately 45.degree. F. (25.degree. C.) lower, the 
fabric-covered window showed a 64.6% reduction in heat loss compared with 
a bare window. 
Additionally, some of the same metalized fabric was tested for shrinkage 
and appearance after machine laundering according to AATCC 135 B 
@105.degree. F. (about 40.degree. C.). The tested samples fell well within 
recommended shrinkage tolerances and had a retention of high metallic 
shine rated "good to excellent" per procedure AATCC 124 and visual 
examination; this retention of metallic was stated to be the best ever 
observed by the testing company. 
TOP COATING 
In an attempt to provide a gold color to a fabric, while metalizing with 
inexpensive aluminum, a length of polyester single-knit fabric was 
calendered under heat and pressure, and then metalized with aluminum to 
produce a high brilliance metalized surface. A small amount of Neoza Pon 
yellow 141 dye, from BASF Wyandotte Corp., was dissolved in isopropanol, 
and this dye was added to Solucote 385, a polymerizable urethane coating 
material obtainable from Soluol Chemical Co., Inc. of West Warwick, R.I. 
This was diluted to a solids content of approximately 36%, with 
isopropanol. The system had a viscosity of about 500 centipoise. The 
fabric was then rotogravure printed with this solution, and then heat 
cured for approximately 2 minutes at 135.degree. C. (275.degree. F.). A 
brilliant gold color was achieved. 
A first portion of the gold fabric was cold-water washed, and showed no 
loss of brilliance or gold color. A second portion was dry cleaned by a 
commercial dry cleaner using a perchlorethylene solution. The dry cleaning 
process removed the gold color, although at least some of the polyurethane 
coating remained on the fabric. 
I have finally obtained a successful gold color by selecting Lavaderm 
yellow, a true solution of an anionic metal complex dye obtainable from 
Mobay Chemical Corp. This was diluted in alcohol, and added to Soluol No. 
10214A, a urethane similar to Solucote 385, having approximately 43% 
solids. The resulting system had a viscosity of approximately 6000 
centipoise. This was applied as a top coating onto another length of high 
brilliance fabric used for the unsuccessful attempts described above, 
using a Meyer bar coating rod and curing in a laboratory oven at 
135.degree. C. (275.degree. F.) for approximately 2 minutes. Again a 
brilliant gold color was achieved. A portion of the length was coldwater 
washed without effect on appearance. A second portion was dry cleaned as 
before, but in this case the brilliant gold was not affected. This coating 
thus provides a desired color change, as well as protecting the metal 
coating from abrasion and reducing any edge ravel which might affect the 
fabric. 
This system, or one like it, could effectively be applied to single-knit 
polyester fabrics on a production basis by knife-over-roller coating. If a 
woven polyester is to be similarly coated, because of its lower stretch 
either knife-over-roller or common coating techniques such as floating 
knife should be equally effective. 
ALTERNATIVE EMBODIMENTS 
It will be clear to those of ordinary skill in the fabric converting art, 
upon reading the above descriptions, that many other fabrics and process 
variations may be used to provide a bright metallic appearing fabric by 
the inventive method. Many different fabrics are believed suitable for 
use, including "long float" fabrics, which have a greater sheen as woven; 
and knitted or any other yarn-base fabric. Other thermoplastic yarns, such 
as nylon, acrylic copolymer, polyacrylonitrile, modacrylic, vinyl, 
tri-acetate and the like can be used, although the optimum temperature and 
pressure may differ from that used for the polyester sample described 
above. Composite yarns having a mixture of thermoplastic and cellulosic or 
other fibers or filaments may also be treated by this method, so long as a 
significant flattening or polishing can be achieved; if technologies not 
known to applicant can produce fabrics from randomly oriented fibers, it 
is believed that the inventive method would be efficacious. Relatively 
open or sheer fabrics would, of course, have a slightly more dense 
appearance, but could also be flattened and metalized. 
Other fabrics which may be or become known, such as cotton or linen, 
perhaps having resin coatings, which are especially desirable for 
clothing, may also be given a glossy metallic look by the inventive 
method, by pressing or compressing still harder, with greater or less 
heat. 
Depending upon the construction and weight of the fabric, temperatures at 
least as low as 385.degree. (197.degree. C.) and as high as 450.degree. F. 
(232.degree. C.) may be preferred for polyesters, and the pressure of the 
calender may be altered at least over the range of 21/2 tons to 13 tons 
per foot (75,000 to 420,000 newtons per meter). Other materials, which 
are less heat resistant than polyesters, may be flattened sufficiently at 
temperatures as low as approximately 250.degree. F. (120.degree. C.). 
Experimentation, as is well known, may be required to determine the 
temperature and pressure and processing speed which will give a desirably 
high metallic shine after metalization. Processing speed or quality may be 
improved by use of a calender whose second, unheated roll is not a paper 
roll. An elastomer-covered steel roll, having a layer of elastomer up to, 
for example, approximately 5/8" (16 mm) thick, and internally water cooled 
to prevent overheating of the elastomer during prolonged operation, has 
been suggested as permitting speeds up to 40 yards (36 meters) per minute. 
Another calender arrangement may use a nylon-covered second roll, cooled 
by contact with a chilled third roll. 
Rather than a calender, flattening may be possible by pressing the fabric 
against a heated roller by a taut blanket, such as is used in transfer 
printing; alternatively, such a roller may be rotated at a different speed 
than the fabric speed to provide a polishing effect. Similarly, one or 
more cans in a series of drying cans can be rotated at varying speeds or 
directions for polishing. Yet another alternative falling within the 
spirit of the invention is a combination of flattening and polishing prior 
to deposition with metal; for this, a friction calender may have fabric 
passed through a first nip between two rolls, around the second of these 
rolls and through a second nip between the second roll and a heated roll 
made of polished steel and rotating with a surface speed typically 11/2 to 
2 times the fabric speed. 
Aluminum will usually be the choice of metal to be vapor-deposited, because 
of its low cost and the wide experience in applying it. However, where 
special appearance or corrosion resistance are paramount, any of many 
other metals or alloys may be applied, such as gold, silver, nickel, 
copper, chromium, or other metals or alloys such as those described in the 
article "Vacuum Coating" in Metals Handbook, 8th ed., vol. 2, pp. 516-528, 
American Society for Metals, 1964 (hereby incorporated by reference). 
Different deposition procedures, such as sputtering, may enable coating 
with materials which prove difficult for use with vapor desposition. After 
metalizing, a top coating of types other than the organic solvent, 
polyurethane family described above, may be helpful to reduce edge 
ravelling of the fabric, prevent abrasion of the metal coating, or allow 
coloration. For example, a clear polyurethane coating has been applied 
using an aqueous carrier. High solids content has been found preferable so 
far, but solids content of at least 35% appear to be effective. Other 
coating systems, such as acrylics, are also within the spirit and scope of 
the invention. Alternatively, although there will be less brightness, if a 
brightly colored fabric is selected, a very thin metallic coating, having 
a substantial transmission of visible light, maybe applied by the 
inventive method, to provide a colored metallic appearance. 
As described above, it will be clear that the inventive method may be used 
to produce a variety of novel fabrics having improved aesthetic 
appearance, at little more than the cost of unmetalized fabric. As 
measured by the appended claims, according to the invention fabrics 
suitable for heat transfer reduction can now be readily mass-produced, so 
as to enable economic reduction of heating or air-conditioning bills for 
residences. A low cost cloth for reflective clothing useful in tropical or 
desert areas, or to reduce radiative loss of body heat in frigid ambients, 
is now provided.