US2703772A - Transfer method for manufacturing infrared reflecting fabric - Google Patents

Description

d 1955 R R. KEITHLY 2,703,772

TRANSFER METHOD FOR MANUFACTURING INFRARED REFLECTING FABRIC Filed Sept-'12, 1952 United States PatentO TRANSFER METHOD FOR MANUFACTURING INFRARED REFLECTING FABRIC Richard Roland Keithly, St. Paul, Minn., assignor to Minnesota Mining & Manufacturing Company, St. Paul, Minn, a corporation of Delaware Application September 12, 1952, Serial No. 309,265

13 Claims. (Cl. 154-96) This invention relates to reflective fabrics of the nature of flexible cloth having an extremely thin and highly reflective visibly continuous metallic surface coating permanently adherently bonded thereto. The extreme thinness and uniformity of the metallic coating is attained by vapor deposition of the metal under high vacuum.

The highly reflective surface effect is obtained by transferring the metallic film to the fabric base from a smooth, polished carrier web on which the metal is initially deposited, thus exposing to-view the mirror-like inner surface of the film of the metallic coating. The reflective cloth product is substantially fully as flexible as the original uncoated cloth.

The novel product of this invention finds particular application as infra-red-radiation-reflecting fabric, for use in the form of protective garments and clothing as well as in draperies and protective curtains. It is also valuable for decorative purposes.

This new product is to be distinguished from prior art laminations of cloth and pre-formed self-supporting metal foil, which are much less flexible, and have entirely different draping qualities, than the original cloth. When such laminated products are repeatedly folded, the metal layer cracks and becomes loosened from the cloth. Stretching, crushing, sewing, or folding of these prior art laminated products, as in making, wearing, and dry-cleaning protective garments, severely reduces their attractiveness and effectiveness. On the other hand, the novel product of this invention has substantially the same draping qualities as the fabric on which it is based, and may be cut, sewed, stretched, repeatedly folded and crumpled, etc. without any substantial loss of metal or diminution of reflectivity.

The new product is also to be distinguished from prior art metallized cloth as produced by direct. application of metal to the cloth, e. g. by sputtering of molten metal.

Such metallized products invariably are low in reflectance, commonly having a dull, semi-metallic appearance. They are quite porous. The sputtered metallic coating is not continuously reflective; it covers only the fibers and does not extend over the intervening interstices. The metallized cloth of this prior art process is also much heavier in weight, and much poorer in draping qualities, than the untreated cloth base.

It has also been found that the direct application of metal to cloth by vapor deposition in a vacuum does not provide a high degree of reflectance, but instead produces a dull and semi-metallic appearance and only a moderate reflectance to infra-red radiation.

Another way by which prior workers have attempted to produce metallized cloth is by applying metallic lacquers or bronzes in liquid form to the cloth. In such cases the liquid binder penetrates the cloth and the fibers, and stiifens the fabric. The binder surrounds the metal particles, and is at least partially exposed to direct radiation and weathering. It has been found that thin' films of transparent binder materials, when placed over a reflective metallic surface, greatly reduce the infra-red reflectivity of the surface; and the metallic-lacquer-coated sheets are similarly deficient in degree of reflection.

Eookbinders and others have long used gold foil transfer sheets for applying gold letters to leather or the like. Such sheets, representing still another example of prior art metal coating, may be prepared by'anchoring gold leaf on a waxed carrier web, and coating the outer surface of the gold layer with a resinous heat-activatible adhesive.

The sheet is then-hot-pressedagainst; the

2,103,772 Patented Mar. 8, 1955 leather with a heated die, to aflix a portion of the metal coating to the leather, and the carrier web is stripped away. The presence of the waxy parting layer helps to maintain the gold leaf in position on the carrier prior to application and to permit stripping away of the carrier after the gold has been adhered to the leather. The heat-activatible adhesive is necessarily resinous and brittle in character so that excess portions of the metal, such as rough edges and interior areas of letters, may be readily removed by brushing. Metal films deposited on wax-treated carrier films by other processes, including vapor deposition and sputtering, and coated with permanently heat-activatible resinous adhesives, have also been used for lettering leather articles or the like. However no such materials, and no other prior art materials or processes of which I am aware, have ever provided highly reflective and flexible full-coated permanently metallized cloth or other fabric such as is now made possible by the present invention.

Thus it is an object of the present invention to provide highly reflective, flexible, full-coated metallized fabric, which may be formed into decorative or utilitarian articles such as radiation-reflective draperies, or protective garments. Another object is to provide metallized fabric which is suitable as a reflective barrier under conditions where previous types of metallized fabrics would be entirely ineffective. A further object is to provide a highly reflective, full-coated metallized fabric of good draping qualities which is also resistant to high temperatures and to organic solvents. A still further object is the provision of means and methods for making these novel and useful products.

I have now found that these and other objects and advantages may be attained by a method which comprises the vapor coating of metal on a smooth-surfaced temporary carrier film, the application to the metal surface of a coating of a suitable highly flexible curable adhesive and the permanent adherent bonding therewith of the metal to the surface of a flexible fabric base, and the subsequent removal of the carrier film to leave a bright and highly reflective exposed metallic surface, all as more fully described and illustrated hereinafter.

In the accompanying drawing, Figure 1 indicates a preferred procedure to be followed, and apparatus to be employed, in preparing the metallized fabric of the invention, and Figure 2 illustrates the various stages in such procedure in terms of the finished product. For convenience, the procedure is described as being continuous; it will be apparent that the unit processes involved may equally well be accomplished separately.

In Figure l, the carrier film 10 passes from supply roll 11 into a vacuum chamber 12 where a metallic coating 14 is applied, the metal vapor being evolved at electrically heated trough or cup 15. This web enters and leaves the vacuum chamber 12 through appropriate seals 13 and 16. The coated film then passes to an adhesive coater where a regulated amount of an adhesive composition is applied to the metallized surface from trough 20 through dip roll 19 and transfer roll 18 to provide, after removal of solvent, a dry, temporarily heat-activatible, heat-curing adhesive layer 22. Proper coating pressure is provided by squeeze roll 17, and volatile solvent is removed in the oven 21. The composite strip is then passed over a heated drum 23 to activate the adhesive. Fabric web 24 from supply roll 25 is forced into contact with the heated adhesive layer 22 by roll 26 pressing against the drum 23. The combined strip then passes through a heating chamber 28 where heat is applied to cure the adhesive. Idler rolls 27 are provided to change the direction of the web and to maintain it in position against the heated drum 23.

The composite web next passes to a pull drum 29 where the carrier film It) is removed and wound up on roll 30, the reflective metallized fabric product 31 being simultaneously wound up on roll 32.

Figure 2 illustrates the several stages in the manufacture in terms of the novel product, the layers being shown in cross-section and on an exaggerated scale, and thecomponents being numbered as in Figure 1. Removal'of solvent in oven 21, and curing of the adhesive in heating chamber 28, is indicated by the cross-hatching in adhesive layer 22 of Figure 2.

The several steps of the process may be carried out separately if desired. The carrier web may be unwound from roll form, metallized, and rewound while supported within the vacuum chamber. The adhesivecoated and dried carrier may be wound into roll form for temporary storage prior to combining with the fabric; in such event it is found desirable either to insert a slipsheet or liner between the convolutions of the roll, or to apply a coating of a low-adhesion backsize to the untreated surface of the carrier web, either before or after applying the coating of adhesive, so as to avoid blocking or adhering together of the adjacent layers in the roll. Polyvinyl N-alkyl carbamate or other equivalent low-adhesion backsize coatings are useful in this connection.

Curing of the adhesive, since it requires rather prolonged heating, is also conveniently carried out separately rather than as a step in a continuous process. The uncured web may be wound up in roll form and placed in an oven for curing of the adhesive, and then removed and cooled to room temperature before stripping the carrier web from the completed product.

Variations of these process steps may be employed with equal effectiveness in many instances. ather than heat-activating the dried adhesive coating as at drum 23 in Figure l, the adhesive may be solvent-activated by the application of a light coating of an appropriate volatile organic solvent. Methyl isobutyl ketone is effective where the adhesive of Example 1 is involved. The coated web is then combined with the fabric under pressure and is preliminarily dried at room or elevated temperature, after which the adhesive is cured by further heating. Another variation involves combining the two webs after only a partial drying of the adhesive coating as first applied; or a light second coating of the adhesive may be applied as an activating medium over a dried initial coating.

Water-dispersed adhesive coatings are applicable, and avoid the difliculties associated with the use of inflammable or toxic organic solvents. Suitable curing agents are incorporated in the poly-butadiene-acrylonitrile, polychloroprenc, or other oil-resistant polymer latex, together with additional plasticizers, tackifiers, thick eners, or other compounding agents as required, and the compounded latex is coated on the metallic surface of the metallized carrier web. The coating is then dried and reactivited, or it may be only partially dried; and while in a tacky state is pressed into contact with the fabric. The structure is then further heated or otherwise treated to cure the adhesive, after which the carrier web is stripped from the finished reflective fabric product. However I much prefer to employ a solution in a volatile organic solvent of an oil-resistant rubbery polymer and a compatible heat-reactive phenolic resin as the adhesive, to form and dry a coating of the adhesive on the metallic surface, to adhere the dried coating to the fabric at an elevated temperature, and then to heat-cure the adhesive to a non-thermoplastic state. This combination of materials and process steps provides for improved control during the processand for maximum performance of the product as a flexible, permanently highly reflective fabric. Hence the following examples, while not limiting the invention thereto, are nevertheless concerned specifically with the type of preferred process and product just identified.

EXAMPLE 1 A coating of aluminum is first formed by vapor deposition under high vacuum on a cellulose acetate surfaced carrier web. The aluminum coating is just thick enough to be visibly opaque. Over this metal coating is next applied a thin layer of adhesive in solution in a volatile solvent mixture, the solvent then being removed by drying in an oven at moderately elevated temperature. The weight of the coating after drying is 3 grains per 24 sq. in. This coated film is then brought to 240250 F. by contact of the carrier web with a steam-heated drum, and a thin closely-Woven rayon cloth is firmly pressed into contact with the tacky exposed adhesive coating. The composite is then heated, for example at 260 F. for 2 hours, to cure the adhesive. After cooling, the cellulose acetate carrier film is easily stripped away, leaving a highly reflective,

visibly continuous and opaque metallic coating on the cloth. The product cannot be distinguished from an uncoated sample of the same cloth with respect to flexibility and draping qualities. Even after severe handling, such as repeated folding or rolling the cloth into a ball and then smoothing it out again, the metallic coating appears to be fully continuous and retains its high reflectivity and decorative appearance.

The carrier web consists of offset paper, a smooth, high gloss, heavily loaded paper, coated with a thin layer of cellulose acetate. The cellulose acetate solution as applied consists of 15 parts by weight of cellulose acetate and 3 parts of dibu'tyl phthalate dissolved in a mixture of 73.8 parts of acetone and 8.2 parts of ethyl alcohol. The cellulose acetate is Hercules Powder Co. grade LH-l having a combined acetic acid content of 54-55% and a viscosity range, measured in solution, of 60-80 seconds. The coating is applied through an S-mil orifice to produce a film which when dried is one mil in thickness and has a smooth, glossy surface. Aluminum foil, 5 mils in thickness, is an example of another sheet material which may be similarly coa'tated, e. g. with cellulose acetate, and used as a carrier we Aluminum is vaporized from the electrically heated trough or cup 15 in the vacuum chamber 12 of Figure l, and deposits on the smooth coated surface of the carrier web in an extremely thin, visibly continuous and opaque film. Heavier coatings may be applied but for reasons of economy it is desirable to use only the minimum weight of metal which produces the desircd opacity and reflectivity.

The adhesive solution consists of 50 parts by weight of rubbery butadiene-acrylonitrile polymer, 50 parts of heat-reactive phenol-aldehyde resin compatible therewith, and 10 parts of dioctyl phthalate, dissolved in 400 parts of methyl isobutyl ketonc. Hycar OR-lS, a copolymer of 55 parts butadiene and 45 parts acrylonitrile, and Varcum 5476 or Durez 175, ketonesoluble heat-reactive (heat-advancing, heat-hardenable) phenol-aldehyde resins, are examples of specific polymers and resins which have proven suitable. The dried residue of such adhesive composition is essentially tack-free at normal room temperatures, but is temporarily softened and rendered tacky on heating. Continued heating causes it to react or set up to a tough but flexible state in which it is no longer rendered soft and tacky by heating and in which it is highly resistant to the softening or solvent action of organic solvents of the types commonly used in dry-cleaning.

The reflectorized product made as above described is highly reflective to intense infra-red radiation and hence finds application in fire-resistance protective clothing as well as for decorative purposes. The high reflectivity of the metallic coating, together with the heat-resistant nature of the underlying layer of cured adhesive, rnakes the product capable of withstanding direct exposure to intense infra-red radiation. The cured adhesive bond is not dissolved nor destructively softened by drycleaning solvents.

Samples of reflective fabric made as just described were compared for infra-red radiation with metallized fabrics produced by conventional methods. The sam ples were suitably suspended under identical controlled constant conditions, and were irradiated by means of an infra-red lamp directed at the reflective surface, while measuring the resulting rise in temperature at the reverse surface. The temperature at the back surface of the sample prepared as described in Example 1 reached a maximum of about 200 F. at 67 minutes. Fabric covered with aluminum foil reacted similarly. On the contrary, fabric coated with aluminum by direct metal vapor deposition, as well as fabric coated with aluminum flake in a lacquer type binder, reached a temperature at the back surface of about 500 F. within two to three minutes under identical test conditions.

Additional samples were given a more severe test by exposing them to the concentrated direct radiation from a radiant heater element. Fabric coated with aluminum by direct vapor deposition charred badly within lO-lS seconds. Fabric coated with aluminum flake in a lacquer binder likewise charred badly within l0l5 seconds. Fabric carrying a layer of metal foil scorched slightly at seconds and was found to be badly scorched but still usable at 300 seconds exposure. Under identical test conditions, the reflectorized fabric of Example 1 exhibited only slight scorching at the end of 300 seconds, and the flexibility and strength of the sheet were not perceptibly altered.

EXAMPLE 2 A pro-formed film of cellulose acetate (150 gage) is employed as the carrier web. It is metallizedand coated with adhesive as in Example 1, and hot-pressed to a coarse asbestos cloth having a thread count of about 9 x 19 threads per inch and a thickness of about 0.06-0.07 inch, the composite being first pressed firmly together at an elevated temperature and then heated for 2 hours at 260270 F. to cure the adhesive,-as in Example 1. The thin flexible acetate film carrier web conforms to the rough surface of the asbestos cloth to provide complete and uniform coverage, and then is easily removed, leaving a highly reflective surface coating on the asbestos cloth. The metallic film remains visibly continuous, fully adherently bonded, and highly reflective even after repeated folding and crumpling of the cloth.

Fire-fighters proximity" suits, incorporating an outer layer of such metallized asbestos cloth have been tested in service; it is found that the wearer experiences no discomfort under such severe conditions as are met in walking along the edge of a test area covered with 500 gallons of freely burning gasoline producing a temperature of 1800-2200 F., the test continuing for more than five minutes. No preliminary soaking of the suit in Water, as is necessary with suits of asbestos fabric normally used for such proximity exposure, is required. The suits are not damaged by the exposure. The high reflectivity of the fabric affords complete protection to the wearer.

EXAMPLE 3 A film of plasticized regenerated cellulose (cellophane) is coated with aluminum by vapor deposition. To the metal surface is then applied an adhesive coating cons1st-' ing of equal weights of a rubbery copolymer of 50 parts butadiene, 40 parts styrene and parts acrylonitrile, and a compatible oil-soluble heat-advancing resinous condensation product of orthophenyl phenol and formaldehyde. The adhesive is applied as a solution in butyl acetate. The dried coating is pressed against a cotton cloth supported on a platen heated at 240-250 F. and the assembly is then further heated for 2 hours at 240-260" F. or for a somewhat shorter time at somewhat higher temperature. The composite is cooled and the cellophane stripped away, leavingthe cloth highly reflectorized and fully flexible.

Coarse-Weave drapery fabrics refiectorized by the ustdescribed procedure were tested both before and after the final heat-curing step to determine the effect of drycleaning. Prior to the dry-cleaning operation it was observed that the heat-cured product was significantly brighter in appearance than the uncured. After cleaning, the heat-cured product was still fully as bright in appearance as it whereas the uncured sample had lost an appreciable portion of the metallic coating and was dull and non-uniform in appearance.

Cotton cloth reflectorized as in Example 3 is h ighly eifective as a liner for decorative draperies, providing a high degree of protection againstsunlight.

Temporarily heat-softening, adherent, highly flexible, heat-curing combinations of rubbery polymers and cornpatible heat-advancing adhesive resins in general provide excellent bonding between fabric and metal when employed as here described. Rubbery butadiene-acrylonitrile copolymers or polychloroprene, and buna-S (rubbery butadiene-styrene copolymer) or natural rubber, are illustrative of suitable rubbery polymers, the normally oil-resistant variety being preferred. Phenol-aldehyde resins such as Bakelite 3360 (an oil-soluble heat-reactive resinous condensation product of an alkyl substituted phenol and formaldehyde), or Varcum 5476 or Durez 175, are particularly suitable. Epoxy resins, derived from polyhydric phenols and aliphatic polyhalides, are also useful. Compositions containing epoxy resins, for example, may be cured at room or slightly elevated temperatures by adding known catalysts to the mixture just prior to coating and combining. The adhesives may be further modified by the incorporation of plasticizers, pigments, tackifiers, other curing agent's, catalysts, etc. as

was before the cleaning operation,

desired. Other curing agents may be substituted in place of the phenolic resin where other means, e. g. thermoplastic tackifier resins, are employed to obtain the required adhesive bonding action.

Additional combinations of oil-resistant rubbery polymer and compatible heat-advancing phenol-aldehyde resin have been tested and are set forth in the accompanying table, together with the results obtained, in order to illustrate the methods employed in arriving at optimum properties and proportions with a specific group of ingredients. These compositions were each applied to the vapor-deposited aluminum coating on cellulose acetate film, as described in Example 2, to a dry coating weight of about 4 /2-5 grains per 24 sq. in.; the coated and dried film was hot-pressed onto cotton sheeting; and

the composite was heat-cured for two hours at 260-270 F. The cellulose acetate carrier film was then stripped away at room temperature, and the reflectorized fabric tested and inspected.

In the table, the adhesive formulation is given as parts by weight of (a) Hycar OR-lS rubbery butadiene-acrylonitrile copolymer, (b) Varcum 5476 compatible heat-advancing phenol-aldehyde resin, and (c) dioctyl phthalate plasticizer. In each case the adhesive achieved a firm bond to the aluminum coating, which subsequently transferred completely from the cellulose acetate film to the fabric. Some of the adhesive formulations did not bond well to the fabric, some were brittle and either flaked away or imparted stiffness to the sheet,

and some were too soft and caused loss of reflectivity on subsequent heating. In general, the formulas of fully acceptable adhesives prepared from these specific components will be seen to lie within the approximate range of 30-70 parts of polymer, 70-30 parts of resin, and not more than about 20 parts of plasticizer.

Table 1 [Effect of variations in adhesive foriinlaltions on properties of retlectorized a no.

Formula ifigg z Flexibility Remarks (1 b c 10 too soft. 70 30 suitable in most cases. 50 50 optimum results. 30 70 suitable in most cases. 30 70 better than 30:70:0. 1O 90 cracks, flakes. 20 80 stiff, but does not crack. 20 80 no better than 20:80:20.

In the preceding examples, the combination of rubbery polymer and heat-advancing phenolic resin provides a high degree of resistance to both solvents and heat when the adhesive mass is cured. Adhesives which are slightly less resistant to heat and to certain classes of solvents, but which are adequately eflfective for many purposes, may be made from non-reactive resins in conjunction with curable rubbery polymers, as will now be demonstrated.

EXAMPLE 4 The adhesive mass consists of parts of rubbery butadiene-acrylonitrile copolymer (Hycar OR-lS), 25 parts of vinyl chloride-vinyl acetate copolymer (Vinylite VYNS), 30 parts of acidic vinyl chloride-vinyl acetate copolymer (Vinylite VMCH), 1 part stearic acid, 2 parts zinc oxide, 1.5 parts sulfur, 1.5 parts benzothiazyl disulfide, 0.15 parts tetramethyl thiuram disulfide, 1.3 parts stabilizer, and 710 parts of methyl isobutyl ketone. The rubbery polymer is first softened on the rubber mill and the remaining non-volatile components, other than the vinyl resins, milled in. The solid components are then dissolved together in the solvent. The solution is coated on the metallized cellulose acetate film of Example 2, and air-dried. The web is adhered to fabric by heat and pressure, as previously described, and the composite heated for 7 hours at 260270 F. to vulcanize or cure the rubbery component. The cellulose acetate film is then stripped away, leaving a highly reflective, visibly continuous aluminum film firmly and permanently adhered to the fabric. The product is highly reflective to infra-red radiation, and remains so after severe handling and after soaking in gasoline andyheat ng n an oven.

The flexibility of the fabric is substantially unchanged.

Gold leaf and similar materials of prior art are ordinarily supported on waxed or oiled carrier webs as hereinbefore noted, the wax or oil serving either as a temporary holding agent or as a parting-layer. Some such parting layer has generally been found essential also where vapordeposited metal films are concerned, in order that the metal layer may be readily separated from the carrier surface. These waxy or oily materials are comparatively easily volatilized, and are troublesome where high-vacuum technique is concerned. Nevertheless their use has been generally thought to be essential wherever subsequent removal of the metal film was desired, as in the transfer sheets used by book-binders and the like.

I have found that prolonged heating of the composite structure, as hereinbefore described, accomplishes a number of unique and advantageous results. Surprisingly, the adhesion or bond between the carrier surface and the metal coating is substantially lowered, so that the carrier, even in the absence of a parting layer of wax or the like, can be completely and easily removed. The adhesive is curved to a solvent-resistant and heat-resistant state, so that the fabric may be subjected to dry-cleaning and to intense irradiation without substantial loss in reflectivity. At the same time, the initial reflectivity of the metal layer is maintained during such curing step, by maintaining the metal layer in full contact with the smooth, polished surface of the carrier. Even though the adhesive layer is unavoidably softened during the early part of the heatcuring operation, and in view of its pressure contact with the fabric might be expected under such conditions to cause disarrangement of the metallic layer, maintaining the carrier web in position on the fabric during the entire curing step nevertheless results in a visibly continuous metal coating of great brilliancy and reflectivity.

In contrast, heating a sheet of fabric carrying an exposed metal coating adhered thereto with a temporarily or permanently thermoplastic adhesive results in immediate loss of a substantial percentage of the original reflectivity of the metal coating.

The fine rayon fabric of Example 1, the coarse asbestos fabric of Example 2, and the cotton fabric of Example 3, are each fully covered and protected by the thin opaque reflective metal layer applied in accordance with the procedures hereinabove described. The thin layer of adhesive, particularly after it is cured, e. g. by heating, is strong and elastic as well as highly flexible, and serves to support and strengthen the extremely thin metal coating. Application of the thin film of highly flexible adhesive,

particularly as a dry, heat-activated coating, permits excellent bonding without any substantial penetration of adhesive into the interstices between fibers or threads, and hence the fabric is not stiffened but instead retains its original flexibility. Curing the adhesive while the carrier remains in contact with the metallic film prevents disruption of the reflective metal surface and maintains full reflective brilliance of the sheet.

An interesting and important property of the reflective fabrics of the present invention is demonstrated by the results of a blocking test performed in accordance with the following described procedure. In this test, a piece of the metallized fabric 8 inches by 8 inches in size is folded at the center with the metallized surface inward, and again folded to produce a 4 x 4 inch square compress, which is placed between two 4 x 4 inch glass plates in an oven, a 4 lb. weight being then placed on the upper plate. The test specimen is allowed to remain under the pressure of the weight in the oven for one-half hour, after which it is tested for ease of unfolding and inspected for appearance. temperature of 180 O, my coated fabric unfolds easily with the slightest possible effort, and the metallic surface is found to be visibly continuous and of undiminished reflectivity. At the same or considerably lower temperatures, metallized fabrics having a vapor-coated metallic surface coat bonded to a fabric base with a temporarily or permanently thermoplastic adhesive layer are found to block or bond together completely, the metal transferring or offsetting from one or the other of the contacting surfaces when the compress is forcibly opened.

Metals such as silver, tin, lead, copper and others are equally applicable for a great many purposes and may be used together with or in place of aluminum, although the latter is generally preferred because of its lower cost, ease of vaporization, and high reflectivity.

Under these conditions, and with the oven at a Likewise,

fabrics of the most diverse structure, either woven or unwoven, fine or coarse, regular or irregular, and of a wide variety of materials including cellulose, silk, wool, glass, rayon, nylon and other synthetics, and mixtures thereof may be metallized by means of the practices of this invention. Paper, fibrous wadding, and other flexible fibrous sheet material likewise may be provided with adherently bonded reflective coatings by the methods herein described. The fabric may be pre-treated, or may form a part of another article; for example, rubberized fabric, or fabric-faced rubber articles, may be provided with a firmly bonded reflective metallic surface coating in accordance with the principles of my invention.

Both self-supporting smooth films and fibrous or other base sheets coated with continuous smooth surface films are suitable as carrier members for the adhesive-coated metal film, as indicated by Examples 1-3. Films of materials such as terephthalic acid alkyd resin (Mylar film) and cellulose acetobutyrate are applicable for this purpose. it is necessary to select a carrier web surface which is not too greatly affected by the particular solvent or other volatile liquid vehicle employed in the adhesive composition and does not soften or deteriorate unduly on exposure to the prolonged heating ordinarily required for curing or vulcanizing the adhesive. Cellulose acetate film, or cellulose acetate coated paper as described in connection with Example 1, is useful under a wide range of conditions and is preferred. Parting layers, such as waxes, may be included, and are of value where the metal adheres excessively to the unprotected carrier surface, but are ordinarily not required and are omitted in my preferred practice as exemplified in Example 1.

What is claimed is as follows:

1. In the manufacture of a reflective fabric, the method comprising depositing a visibly continuous thin metal film on a smooth-surfaced flexible carrier, forming on the metallized surface a thin coating of a curable, highly flexible adhesive bonding composition, adhering the adhesive layer to the surface of a fabric base under pressure, curing the adhesive bonding composition to a solvent-resistant and heat-resistant state, and then stripping the carrier from the metal film.

2. In the manufacture of a reflective fabric, the method comprising depositing a visibly continuous thin metal fun on a smooth-surfaced flexible carrier, forming on the metallized surface a thin, dry, non-tacky coating of a curable, temporarily heat-activatible, highly flexible adhesive bonding composition, activating said adhesive coating to a temporarily tacky state and pressing the thus activated adhesive layer firmly against a fabric base, curing the adhesive bonding composition to a solventresistant and heat-resistant state, and then stripping the carrier from the metal film.

3. In the manufacture of a reflective fabric, the method comprising depositing a visibly continuous thin metal film from vapor state on a smooth-surfaced flexible carrier, forming on the metallized surface a thin, dry, non-tacky coating of a heat-curing, temporarily thermoplastic, highly flexible adhesive bondin composition comprising a rubbery polymer and a tackifier resin, activating said adhesive coating to a temporarily tacky state and pressing the thus activated adhesive layer firmly against a fabric base, heating the resultant composite web for a time and at a temperature sufficient to cure the adhesive bonding composition to a solvent-resistant and heat-resistant state, and then stripping the carrier from the metal film.

4. In the manufacture of a reflective fabric, the method comprising depositing a visibly continuous thin aluminum film from vapor state on a smooth-surfaced flexible cellulose acetate carrier, forming on the metallized surface a thin, dry, non-tacky coating of a heat-curing, temporarily heat-activatible, highly flexible adhesive bonding composition comprising about 30-70 parts by weight of rubbery butadiene-acrylonitrile copolymer and correspondmgly about 7030 parts of heat-advancing phenolaldehyde resin compatible therewith, hot-pressing the adhesive-coated web against a fabric base, heating the rcsultan t con".posite web to cure the adhesive bonding composition to a solvent-resistant and heat-resistant state, and then stripping the carrier from the metal film.

5. As a new article of manufacture, a flexible solventresistant reflective fabric capable of being dry-cleaned 1n organic solvents and of exposure to intense infra-red radiation without substantial diminution of reflectivity, and comprising a fabric base, an extremely thin, opaque,

visibly continuous, highly reflective metal surface layer, and an intervening adhesive bonding layer comprising a thin, highly flexible, solvent-resistant and heat-resistant, cured film of an adhesive bonding composition.

6. As a new article of manufacture, a flexible solventresistant reflective fabric capable of being dry-cleaned in organic solvents and of exposure to intense infra-red radiation without substantial diminution of reflectivity, and comprising a fabric base, an extremely thin, opaque, visibly continuous, highly reflective metal surface layer, and an intervening adhesive bonding layer comprising a thin, highly flexible, solvent-resistant and heat-resistant, heat-cured film of a heat-curing, temporarily thermoplastic, adhesive bonding composition comprising an oilresistant rubbery polymer and a tackifier resin.

7. As a new article of manufacture, a flexible solventresistant reflective fabric capable of being dry-cleaned in organic solvents and of exposure to intense infra-red radiation without substantial diminution of reflectivity, and comprising a fabric base, an extremely thin, opaque, visibly continuous, highly reflective aluminum surface layer, and an intervening adhesive bonding layer comprising a thin, highly flexible, solvent-resistant and heatresistant, heat-cured film of a heat-curing temporarily thermoplastic, adhesive bonding composition comprising about 30-70 parts by weight of rubbery butadieneacrylonitrile copolymer and correspondingly about 70-30 parts of heat-advancing phenol-aldehyde resin compatible therewith.

8. As a new article of manufacture, a flexible solventresistant reflective fabric capable of being dry-cleaned in organic solvents and of exposure to intense infra-red radiation without substantial diminution of reflectivity, and comprising a fabric base, an extremely thin, opaque, visibly continuous, highly reflective aluminum surface layer, and an intervening adhesive bonding layer comprising a thin, highly flexible, solvent-resistant and heatresistant, heat-cured film of a heat-curing, temporarily thermoplastic, adhesive bonding composition consisting essentially of about 50 parts by weight of rubbery butadiene-acrylonitrile copolymer, about 50 parts of heatadvancing phenol-aldehyde resin compatible therewith, and about parts of a liquid plasticizer.

9. As a new article of manufacture, a flexible sheet material comprising a smooth-surfaced flexible carrier, a thin, opaque, visibly continuous metal film temporarily adhered to the smooth surface of said carrier, and a firmly adherent, thin, non-tacky coating, on the exposed metal surface, of a temporarily heat-activatible and heat-curing hlghly flexible adhesive bonding composition comprising an oil-resistant rubbery polymer and a tackifier resin.

10. As a new article of manufacture, a flexible sheet material comprising a smooth-surfaced flexible carrier, a thin, opaque, visibly continuous aluminum film temporarily adhered to the smooth surface of said carrier, and a firmly adherent, thin non-tacky coating, on the exposed metal surface, of a temporarily lieat-activatible and heat-curing highly flexible adhesive bonding compos1t1on comprising about 30-70 parts by weight of rubbery butadiene-acr'ylonitrile copolymer and correspondingly about 7030 parts of heat-advancing phenol aldehyde resin compatible therewith.

11. As a new article of manufacture, a flexible sheet material comprising a smooth-surfaced flexible carrier, a thin, opaque, visibly continuous aluminum film temporarily adhered to the smooth surface of said carrier, and a firmly adherent, thin, non-tacky coating, on the exposed metal surface, of a temporarily heat-activatible and heat-curing highly flexible adhesive bonding composition consisting essentially of about parts by weight of rubbery butadiene-acrylonitrile copolymer, about 50 parts of heat-advancing phenol-aldehyde resin compatible therewith, and about 10 parts of a liquid plasticizer.

12. An article of protective clothing having as an exposed component thereof a reflective fabric as defined in claim 5.

13. Decorative sun-proof draperies having a decorative fabric facing and a reflective lining, said lining being the reflective fabric of claim 5.

References Cited in the file of this patent UNITED STATES PATENTS 345,442 Millot et al July 13, 1886 1,802,066 Rado Apr. 21, 1931 2,400,390 Clunan May 14, 1946 2,447,541 Sabee et al. Aug. 24, 1948 2,625,496 Swift et al. Ian. 13, 1953 2,638,428 Gordon et al. May 12, 1953 FOREIGN PATENTS 23,688 Great Britain Oct. 12, 1911 485,965 Great Britain May 27, 1938

Claims (1)

1. IN THE MANUFACTURE OF A REFLECTIVE FABRIC, THE METHOD COMPRISING DEPOSITING A VISIBLY CONTINUOUS THIN METAL FILM ON A SMOOTH-SURFACED FLEXIBLE CARRIER, FORMING ON THE METALLIZED SURFACE A THIN COATING OF A CURABLE, HIGHLY FLEXIBLE ADHESIVE BONDING COMPOSITION, ADHERING THE ADHESIVE LAYER TO THE SURFACE OF A FABRIC BASE UNDER PRESSURE, CURING THE ADHESIVE BONDING COMPOSITION TO A SOLVENT-RESISTANT AND HEAT-RESISTANT STATE, AND THEN STRIPPING THE CARRIER FROM THE METAL FILM.

Images