Metallized Article

Abstract

Fibrous article with heat-and-light reflecting quality provided by a metal coating. The metal coating is overcoated with a mixed resin system. The article thus produced has enhanced stability of the fibrous substrate due to the heat and light protection provided by the coatings and also has enhanced strength due to the coatings consistent with substantially retaining hand and softness of the fibrous article. The metal coating is uniquely abrasion and mar resistant, water repellent and launderable and dry cleanable consistent with high moisture vapor transmission of the article (breathability).

Description

This invention relates to fibrous articles -- e.g. fabric (woven or bonded), paper and fiber (filament or yarn) to be formed into fabric or paper and particularly to fibrous articles coated with metal to provide heat and light reflectance for decorative and functional (insulation) purposes.

The principal known fabric or fiber metallizing methods are (1) application of metal flakes in a plastic matrix, e.g. U.S. Pat. Nos. 2,630,620; 2,767,104 and 3,220,871 embodied in Milium (registered trademark of Deering - Milliken Company) and (2) vacuum metallizing of a fabric or fiber, e.g. British Pat. Nos. 663,251; 721,879; 800,093; 816,906; and U.S. Pat. Nos. 2,912,345; 2,921,864; 2,907,678 and German Pat. No. 1,182,631 embodied in Metalon and Insalune (registered trademarks) fabrics (see Man Made Textiles Magazine (Jan. 1965) 43 and Textile World (May 1965) 113).

Both of these processes have significant limitations in regard to abrasion and mar resistance and launderability of the metal coating.

It is the object of the invention to provide improved metallized fibrous articles characterized by improved abrasion and mar resistance, corrosion resistance, launderability, dry cleanability and water repellence consistent with high moisture vapor transmission (breathability) of the articles.

It is a further object of the invention to provide enhanced strength and stability of the articles consistent with the foregoing object.

It is a further object of the invention to provide substantially unimpaired hand and softness of the treated fibrous article consistent with the foregoing objects.

It is a further object of the invention to provide very high heat and light reflectance consistent with the foregoing objects.

It is a further object of the invention to provide an economical method of manufacturing such an article with a single step post coating following metallizing.

In general the improved fibrous article is made by metallizing a fibrous article in a vacuum chamber, removing the article from the vacuum chamber and dipping it into a mixed resin solution to form an overcoat resin layer over the metal layer.

The metallizing may be practiced on a filament or yarn later formed into a fabric or directly on a woven or bonded fabric or paper. The fiber involved may be natural or synthetic or a mixture as in cotton-polyester woven fabrics. Metal may be applied directly to the fiber or the fiber may be pre-coated prior to the application of metal to reduce outgassing from the fiber in the metallizing vacuum chamber and to enhance adhesion of metal to fiber substrate.

Preferably the metal is applied to a thickness of about 10.sup.-.sup.6 inches but may be as thin as 10.sup.-.sup.7 or as thick as 10.sup.-.sup.4 inches. The metal forms a continuous layer along at least one side of the fibrous article but without bridging gaps or openings in the article, to leave the breathability of the article unhindered. The continuity of the film provides a better reflectance than a flake coating or a similar metallized film which simulates a flake coating due to crocking or crazing or removal of intermittent portions thereof due to abrasion or laundering or the like.

The overcoat is a mixed resin system of high adhesion to the metal and low cohesion within itself. The overcoat is applied with a carrier of organic solvent or water which is driven off by heating to effect cure of the mixed resin system. The resultant product is found to have a higher moisture vapor transmission with the overcoat than without it (where fibers are metallized, the moisture vapor transmission can only be evaluated after subsequently forming into a fabric). The overcoat is selected to provide a high transparency to infrared radiation in the range of visible to near infrared wavelength (including 8-9 microns) so that reflectance of the article to such radiation with the overcoat is at least 90 percent of reflectance without it.

In a first and preferred embodiment of the invention, the overcoat is made of a mixed polyurethane-silicone resin system with organic solvent carrier. In other embodiments, mixed polyacrylic-silicone resin systems with water carrier are used. The urethane-silicone coating is designed primarily for outdoor application with the constituents selected for ultraviolet stability, fungus and mold resistance, resistance to weather and humidity extremes as well as water repellency and the other objects stated above. The water based acrylic-silicone coatings are the most readily adaptable to the padder-tenter applicator arrangements common in the textile industry and more adaptable to aerosol spraying for consumer use (and less flammable than the organic system), but afford water repellency to a lesser degree.

The mixed resin system perform overlapping functions. The first resin in the coating -- a film forming polymer, e.g. acrylic (including methacrylic etc.) or the urethane -- provides an adherent protective layer for the metal. Among acrylics, melamine cross linked acrylic acid polymers are preferred (e.g. Union Carbide LKSB 0200). The film is very thin to afford high reflectance of radiation by the article as a whole. The second resin is a mixture of silicones including typically, the conventional water repellent polydimethyl siloxane marketed as Dow Corning's DC-200 or General Electric's SF-96 solutions or Dow Corning DC-36 emulsion. Also included are a mar resistant silicone (e.g. Dow Corning DC-11) and a coupling agent (e.g. Dow Corning DC-600). The film forming polymer alone would bridge over and block moisture vapor in the absence of the silicones. The silicones alone would not adhere well to metal.

The practice of the invention will be best understood from the following nonlimiting examples:

EXAMPLE 1 (05158-3B)

a. 74 parts (by volume) of solvent (70 toluene; 14 Cellosolve) mixed with 8 parts of polyurethane solution (25 percent solids in xylene solvent) and mixed rapidly with pneumatic agitation.

b. a 10 percent solution of polyvinyl butyral in alcohol was mixed with solvent (3 parts PVB, 1 solvent). The solvent was 1 percent glyoxal in Cellosolve. The glyoxal per se was 40 percent solids in water.

c. Modified silicones were similarly mixed (1 part SF-96, 1 part DC-600, 1.5 part DC-11) Before mixing the SF-96 was reduced to 1 percent intoluol, the DC-600 to 1 percent in Cellosolve, the DC-11 to 0.5 percent in Cellosolve.

d. The three components (a) (b) (c) were mixed. Then 0.1 parts of Dow Corning F-1-1522 (glycol modified polydimethylsiloxane) was added to 100 parts of the mixture and this was mixed.

e. Swatches of Dacron (trademark) polyester fabric and ripstop nylon fabric were placed in a vacuum metallizing chamber and aluminum was evaporated in the chamber under vacuum and condensed on the fabric substrates to a decorative grade thickness (about 10.sup.-.sup.6 inches). The fabrics were removed from the chamber and dipped in the mixture with some fabrics set aside for control. After dipping the fabrics were squeezed through rollers and then exposed to a radiant heater to raise their temperature over 250.degree. F for 5-30 minutes or over 300.degree. F for 1-3 minutes.

The fabrics were laundered in a washing machine (warm water settings -- 100.degree.-120.degree. F) with household detergent (alkaline). Those nylon fabrics which had only metal coating lost their metal on one washing. Polyester fabrics with metal only lost metal in some cases, retained it in others. Both nylon and polyester fabrics with metal and resin overcoat retained their metal coating with repeated washings.

Radiation reflectance of the fabrics was measured with a spectrophotometer in the wavelength range from visible light to 2.5 microns (near infrared). Averages of measured values were ##SPC1##

EXAMPLE 2 (4048-4 SERIES)

A variation of the Example 1 coating was prepared as follows:

urethane (TG-100*) 12 parts toluene 73 parts modified SF-96** 5 parts modified DC-600*** 5 parts modified DC-11**** 5 parts

Ripstop nylon was vacuum metallized to decorative grade thickness and overcoated with the above resin mixture by immersion, pressing between rollers and suspending in an oven to heat to about 250.degree. F for 5 minutes and in some cases for 30 minutes.

The fabrics were home laundered as in Example 1. Uncoated (no resin) fabrics lost their metal completely in one washing. Fabrics having the overcoat retained substantially all their metal. Best retention of metal and metal luster was in a fabric which had a 30 minute cure.

Swatches of the fabrics were submitted to Lowell Technological Institute Research Foundation for laundering and dry cleaning per tests:

Laundering:

AATCC Method 96-1960T, Test II

Dry Cleaning:

AATCC Method 108-1963T using both perchloroethylene and stoddard solvent.

The sample swatches after testing showed the same results as the home laundering. The nonresin coated swatches had lost all metal. But the overcoated samples retained it (entirely for laundering and stoddard solvent, but with some blushing for perchloroethylene solvent).

EXAMPLE 3

Nylon and polyester fabrics metallized and overcoated as in Example 1 were made into bags and filled with water with 1 to 2 inches head and suspended in air. These bags held the water several weeks without dripping. The bags were also exposed to spilled coffee and no stain resulting. Similar bags made of metallized fabric without overcoating would not hold water. Measurements were made of moisture vapor transmission and it was found that the metallized and overcoated fabrics had higher transmission than the fabrics, as uncoated, or coated with metal alone.

EXAMPLE 4 (12028)

A cotton fabric was vacuum aluminized and topcoated with a resin system of Example 1. The metal was lost in washing due to poor adhesion of the metal per se to the cotton.

A further attempt was made to overcome this by pre-washing a cotton fabric and pre-coating it with a base coat prepared as follows:

a. Mix 34 parts (by volume) of water with 1 part of a solution of 4 percent hydroxymethyl cellulose in water

b. Mix (a) with 20 parts acrylic emulsion HA-8 or Rohm & Haas K-87 (conventionally used in fabric finishing)

c. Mix (b) with 1 part diluted acetic acid (10 percent in H.sub.2 O)

d. Mix (c) with 1 part sodium silicate - 3H.sub.2 O

e. Filter (d) through sheer Dacron and let stand. Cure at 350.degree. F for 3 minutes.

The pre-coated cotton was aluminized to decorative grade thickness and topcoated as in Example 1. It exhibited excellent resistance to laundering at 104.degree. F water and cold water detergent with no apparent metal loss.

EXAMPLE 5

In variations of the Example 4 experiment it was observed that standing for a week enhanced the adhesion of metal coating and topcoat. It was also observed that the base coat as applied to cotton and other natural and synthetic fabrics gave the metal coat a substantial resistance to laundering even without topcoat.

However the above topcoat improved the resistance to laundering and is also necessary for abrasion resistance and corrosion resistance in outdoor use.

EXAMPLE 6

A top coat was prepared as follows:

a. Mix 10 parts acrylic (0200) solution (55 percent solids) with 73 parts water

b. Mix (a) with 10 parts DC-600 silicone (reduced to 20 percent in Cellosolve)

c. Mix 5 parts DC-11 silicone (1 percent in Cellosolve) with (b)

d. Mix 2 parts DC-36 silicone with (c).

A metallized ripstop nylon was immersed in it, squeezed and dried at 300.degree. F for 3 minutes. Upon laundering it held most of its metal, but with some dulling, while a similar metallized fabric without topcoat lost its metal in laundering. The fabric hand was similar with and without top coat.

EXAMPLE 7

50 parts of the Example 6 topcoat buffered with a small addition of NH.sub.4 Cl to 8 ph, were mixed with 50 parts distilled water and 90 parts of the mixture was mixed with 2 parts DC-37 silicone. Metallized triacetate fabric was topcoated with this mixture and dried at 300.degree. F for 15 minutes. The resultant fabric laundered with only slight metal loss, exhibited a bright luster and good hand was breathable.

EXAMPLE 8

The Example 7 coating, without the additional DC-37 silicone, was applied to metallized Tyvek (DuPont registered trademark) bonded polyethylene fabric with similar results (good resistance to laundering compared to essentially no resistance for metallized Tyvek without topcoat) and was breathable (through pinholes punched through prior to metallizing). Curing of the top coat was limited to 150.degree. F, to avoid damaging the Tyvek.

EXAMPLE 9

The following modified acrylic-water base formulation was found to give the best protection to Tyvek and Reemay fabrics consistent with good hand:

85 parts distilled water

3 parts Rhoplex K-87 self-cross-linking acrylic

1 part DC-36 silicone

2.5 parts Acetic acid (4 percent in water)

5 parts NH.sub.4 Cl (10 percent in water)

2 parts xylene

0.5 parts DC-100 (1 percent in Cellosolve)

0.5 parts DC-11 (1 percent in Cellosolve)

0.5 parts Dow Corning F-1-522 glycol modified dimethylpolysiloxane.

Three compositions of the invention are now stated with total solvent and/or water stated separately and on a weight of liquid component basis (expressed as approximate percent of total weight of the composition). The second column gives the percent of solids in each component (dissolved or emulsified). Exact proportions are not critical.

COMPOSITION A

Component Quantity (1%) % Solids __________________________________________________________________________ Amine cross linked acrylic 11% 55 DC-36 hydrophobic silicone 2 35 SF-96 hydrophobic silicone (50 Centistokes) 2 100 DC-600 coupling silicone .2 63 DC-11 mar resist silicone .04 10 Cellosolve 23 0 Distilled Water 62 0 __________________________________________________________________________

COMPOSITION B

Component Quantity (%) % Solids __________________________________________________________________________ Self cross link acrylic emulsion 3.2% 46 DC-36 1 35 DC-600 .000045 63 DC-11 .000045 10 Dow Corning F-1-1522 .4 100 Cellosolve .85 0 Xylene 875 0 Ammonium Chloride .025 100 Glacial Acetic Acid 1.15 0 Distilled Water 92.5 0 __________________________________________________________________________

COMPOSITION C

Component Quantity (%) % Solids __________________________________________________________________________ Polyurethane 9.7% 25 DC-600 .01 63 DC-11 .01 10 F-1-1522 .1 100 SF-96 .01 100 Polyvinyl butyral .3 100 glyoxol 1.8 40 Cellosolve 18 0 isopropyl alcohol 2.3 0 toluol 68 0 __________________________________________________________________________

The scope of the invention includes various other metals -- copper, zinc, tin, gold, silver, bright platinum, bronze, Wood's metal and equivalent metals of which can be applied to fibrous article substrates as thin films to afford bright reflectance. The coating may also be deliberately absorbent such as a platinum black coating. The coating may also be in sub-layers for providing iridescent effects, but such sub-layers would add up to a single thin deposited layer, in contrast to the three dimensional structure of Milium coatings which have overlapping and nonparallel metal flakes in a plastic matrix. The metal layers of the present invention are essentially continuous in local zones, but are, of course, discontinuous to the extent the fabric is discontinuous in the openness of its weave for moisture vapor transmission and may be made further discontinuous by application of the metal in a screen pattern or the like for decorative effects.

The method of application of the metal(s) may be vacuum evaporation, sputtering, pyrolytic or chemical vapor deposition, or electroless or any method which provides a sufficiently thin metal coat which is continuous to the extent indicated and also not bridge over an open fabric weave.

The film forming resin has as a basic criterion that it must be capable of reacting and cross-linking with the hydrophobic component (silicone) when cured. The film forming polymer resin used in the topcoat may be acrylic, acetal, ester, phenolic, ethers and epoxies, vinyls and urethane base polymers including copolymers thereof. The key criteria is a film forming capability without excessive use of plasticizers and avoidance of stiffening the fabric substrate. Cohesiveness of the resin is limited by the combination with the hydrophobic silicone of the topcoat and enhanced adhesion is obtained to the metal in metal coated fabric areas and to the fabric in fabric areas uncoated with metal. Coupling of several of the water repellent topcoats of the present invention to fiber surface is not a surprising result. Coupling to substantially continuous metal surface to the degree indicated herein and consistent with the objects of the invention is unique.

The finished fibrous article (whether treated as a fabric or treated as a fiber and then formed to a fabric or paper) may be used for clothing, draperies, clothing linings, tentage, outdoor boat and car covers, umbrellas, sleeping bags and the like. In connection with use near engines, the article has enhanced resistance to gasoline or oil attack.

The combination of metal and topcoat protects the substrate (e.g. nylon fiber) from actinic decay due to ultraviolet and infrared radiation. The principal protection in this regard is provided by the metal while the topcoat protects the metal from attack by dust, bacteria, chemicals and water exposure of outdoor use as well as in laundering and dry cleaning.

The metal coat also affords static resistance to the article.

The finished article also has enhanced strength which is particularly noticeable for sheer fabrics and paper. The strength of Kleenex tissues was doubled when metallized and topcoated as set forth herein.

The metal is normally applied to one side of a fabric or fiber but may be applied to both sides. The topcoat is applied to both sides.

The essential features of the topcoat system are (a) a film forming polymer resin adherent to the metal which may be in polymer form as mixed or after curing, and (b) a hydrophobic (including mar resistant) silicone of known composition R.sub.n SiO(4-n)/2 where R is selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, cycloaliphatic, or alkenyl radicals and n is from 1.0 to 2.9. Water in amounts which may be small are necessary to enhance silicone polymerization in accordance with known practice for use of these compositions and (c) carrier.

The "solids" coating of the initial mixture composition (including liquid form components of 100 percent "solids" composition) is from 1 to 10 percent of the total topcoat composition, the balance being carrier water and/or solvents essentially all removed during curing.

The component (a) is 50-98 percent of the solids content and the component (b) is 2-50 percent of the solids content. The component (b) includes a major portion of a hydrophobic silicone (including mar resistant) or mixture of such compositions and a minor portion (1 to 50 percent) of a coupling agent effective to couple to the hydrophobic silicone and the component (a). It is optional whether the coupling agent or agents are also capable of coupling effectively to the metal and/or fabric. The coupling agent is not necessarily hydrophobic, per se. The Dow Corning handbook entitled "Silane Coupling Agents" (published 1967) gives a particularly good analysis of coupling agents for various film forming polymers. While the handbook analysis is not in terms of coupling the polymer to another silicone component, it has been determined by my experiments that the selections stated in the book are adequate for this purpose to the extent necessary in protecting metallized fabrics.

The silicones now widely used or useful as conventional water repellent fabric finishes all serve to varying degrees the purpose of reducing the web forming tendency of the components (a). Preferred choices have been indicated above.

Claims

What is claimed is:

1. A fibrous article comprising a fiber substrate having at least two sides and coated with a metallic layer on at least one side, the metallic layer being overcoated with a layer of mixed resins adhering to the metal, the metal coating having a thickness between 10.sup.-.sup.7 and 10.sup.-.sup.4 inches and being essentially in a single layer along the coated side of the fiber and the resin coating including a resin which forms a film and a component which is hydrophobic and cross-linked with the film forming resin, the mixed resin layer being sufficiently thin and transparent to radiation in the region of visible to near infra red wavelengths to preserve a reflectance of the article to said radiation which is at least 90 percent of the reflectance with no resin overcoating, the article having a moisture vapor transmission with the mixed resin higher than that without the resin and wherein the hydrophobic component comprises a silicone water repellent and a silicone coupling agent.

2. The article of claim 1 wherein the mixed resins as a coating mixture comprises 1-10 percent by weight of included solids in liquid dispersed form, the solids comprising 50-90 percent by weight of an adherent film forming resin and 2-50 percent by weight of a resin modifying component comprising at least one polysiloxane substituted with substituents selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, cycloaliphatic or alkenyl radicals.