US2748019A - Metallized fabric - Google Patents

Description

May 29, 1956 A. F. SCHRAMM, JR

METALLIZED FABRIC Filed Oct. 1. 1955 INVENTOR. flujasi 17' Jclzramm, /11

United States Patent METALLIZED FABRIC August F. Schramm, Jr., White Plains, N. Y.

Application October 1, 1953, Serial No. 383,593

2 Claims. (Cl. 117-31) This invention relates to metallized sheet material and the method of making it. The invention relates, more particularly to a sheet of textile fabric or the like having on one surface at least thin flakes of metal adhered to the sheet.

There have been numerous efforts to increase the heat insulating effect of fabric by applying a layer of minute particles of aluminum foil over the fabric. An article of this type is that described in U. S. Patents 2,630,573 and 2,630,620. In the process and product of these patents, permeability of air breathing properties is dependent upon inaccessibility of certain parts of the fabric structure to the applied metallizing composition and film rupture after application of the composition, or is introduced by baking and consequent shrinkage of the previously applied plastic and aluminum composition. Also the flakes are suspended in a solution of plastic in which they are sprayed upon the fabric, so that the flakes in the finished product are covered on faces and edges by plastic material.

In my improved metallized fabric spaces between the metal flakes are in free communication with the meshes in the fabric or other openings in the treated sheet material. Smoke may be blown freely through the treated product; easy permeability to air is thus demonstrated. My process makes unnecessary breaking, distortion, or baking to cause shrinkage of previously applied material. My process avoids the use of organic solvents which frequently involve fire hazard as well as expense.

Briefly stated, my invention comprises the process of and the product resulting from applying, to a surface of a permeable sheet, fine particles of normally solid binder material dispersed in a liquid non-solvent for the binder material, then applying to the same surface small flakes of metal in uncovered form, that is, not suspended in a plastic or like solution, volatilizing the liquid non-solvent from the dispersion, pressing the flakes of metal against the binder while the binder is in softened condition, and then hardening the binder.

This application is a continuation in part of my copending application for U. S. patent Serial No. 372,406 filed August 4, 1953. The invention utilizes parts of the technique of equipment described in my Patent 2,603,575 issued on July 15, 1952.

The invention will be illustrated by description in connection with the attached drawings to which reference is made.

Fig. 1 is a diagrammatic side view of suitable equipment for use in practising the process of the invention.

Fig. 2 is a plan view of the metal-coating roller.

Fig. 3 is a magnified perspective view of the finished, metallized fabric partly broken away for clearness of illustration with the binder particles, metal flakes, and

This is mounted on conventional support 4, drawn over guide roller 6, and then over reverse coating roller 8 operated by the directly driven roller 10 which, at its lower portion, dips into the tank 12 of aqueous emulsion 14 of binder material. The film of binder emulsion supplied to the fabric by the roller 8 is shown in exaggerated thickness at 16.

Driven roller 18, for supplying metal powder to the surface of the fabric carrying the previously applied dispersion of the binder, dips into metal powder 19 in container 20. Doctor blade 22, in a usual kind of mounting, supplies a straight edge adjacent to the surface of the roller 18 after issuance, in its rotation, from the tank of metal powder, so as to control the thickness of layer of the powder which passes under the doctor blade to the fabric. Control and positiveness of feed is also effected in part by the diagonal grooves or engravings 24 on the metal supply roller 18.

Roller 26 rests upon the sheet material 2 at a position just above the roller 18, so that there is slight but appreciable pressure of the metal particles at this point against the binder dispersion on the cloth.

A thin layer 28 of the metal flakes remains on the cloth issuing from the pass between the rollers 18 and 26.

The cloth with binder and metal flakes then passes against a tapping device such as the member 30 of hexagonal cross section driven in rapid rotation. The edges of the hexagonal member, striking back of the cloth at closely spaced intervals, causes falling away of flakes of the metal not adhered to the sheet material, that is, not in direct contact with particles of the binder material on the surface of the sheet.

Receiver 31 for the metal flakes so removed terminates close to the treated side of the sheet material and is suitably under slight vacuum, so that there is a gentle movement of air through the sheet material. While not necessary to permeability of my product, this slow movement of air causes additional removal of insecurely lodged metal. To avoid scraping action, small guide rollers 32 are provided at the positions of contact of the vacuum line with the treated surface of the fabric. The remaining layer of metal flakes extends over all parts of the face of the cloth, that is, over the positions of intercrossing of the strands thereof and also over the meshes therebetween.

The sheet with adhered binder and metal flakes is passed through a mist spray chamber 33 with spray nozzle 34. Here there is applied a light mist of binder material, suitably the same in composition as emulsion 14, in limited amount covering, after drying, less than all of the surface of thesheet, so as to leave pore spaces but uniting itself to the binder initially applied.

The sheet is then plied, in one embodiment of the invention, with permeable sheet 35 of the same kind as sheet 2 or different. The composite or laminate so made is pressed between rollers 36 which force the sheet 35' lightly against the freshly sprayed binder. Sheet 35 carries spaced particles 39 of previously applied binder material.

The treated sheet material is then drawn through the warming chamber 37 with heating elements 38 and vent to the hood 40, for exhausting vapor of the non-solvent which is evaporated from the binder dispersion in the warming chamber.

The dried composite then passes in warm condition between the smoothing rollers 42 and 44. These press the metal flakes flatwise with respect to the sheet material and firmly against the plastic binder material that has been softened in the warming chamber 37.

The product then passes through the cooling chamber 46 provided with inlet 48 for cold air and outlet 50. The cooled product then passes over guide roller 52 to usual winding up mechanism 54, care being taken at all times to avoid stretching the cloth to the point of rupture of the binder and aluminum structure thereon.

Driving mechanisms and other accessories to the machine that are not illustrated are conventional. Also materials used in construction of the various parts of the machine are those conventionally used for like parts in other machines except as noted herein. Suitably, the roller is steel with a cloth cover over its cylindrical surface, the roller 8 rubber faced, and the hexagonal roller 30 of steel.

The process will be largely evident from the description of the apparatus that has been given.

Plastic binder material is supplied to one surface at least of the sheet material, in limited proportion less than that required to saturate the sheet. In fact the amount is just enough to moisten the face of the sheet. Then a thin layer of the metal flakes is applied over the dispersion on the sheet. Those of the metal flakes so applied that are not in direct contact with the binder, as shown by non-adherence are removed as by a tapping operation on the back of the sheet while the particles are on the lower side of the sheet. Those not adhered in position are removed by the tapping operation, supplemented in one embodiment of the invention, by those removed also by a slow stream of air drawn through the sheet in the direction of back to face.

The sheet with the binder and adhered particles are subjected to the elevated temperature of volatilization of the non-solvent liquid medium, in which the binder particles are originally dispersed, and of softening of the normally solid binder material. Before the particles of binder have become solid, the flakes of metal are pressed against the binder, generally flatwise with respect to the sheet. The rollers 42 and 44, being cold, set the binder. Then the binder is hardened, as by being cooled from an elevated temperature of softening of it to room temperature.

As to materials, my process is intended for use on textile fabrics of cotton, wool, rayon, and synthetics or mixtures theerof. In such woven, knitted or braided sheet material, the spaces between the metal flakes communicate directly with the meshes between the strands of the fabric as well as at positions where the threads cross each other. Other sheet material may be used, however, including air permeable felted fibrous material, of which paper is an example, and fabrics pretreated for water repellency.

The metal particles are suitably in the formiof flakes of metal foil, that is, flakes of the thinness of metalfoil. Examples are aluminum and bronze powders of the fineness of such powders designed for use as pigment in lacquers. Stainless steel powder is another example. For best reflection of radiant energy, aluminum flakes are used. Because of the anchorage secured by my pressing operation, that orients the particles predominantly in direction generally parallel to the surface of the sheet material being metallized, excessive fineness of the particles is not required. Sizes of 100 mesh and finer are satisfactory.

The binder material must be non-volatile, water insoluble, water dispersible, and normally a solid, this term including a plastic solid. Examples of binder materials that meet these requirements and that are used to advantage are thermoplastic materials including polyvinyl chloride and copolymers with vinylidene chloride or vinyl acetate, polystyrene, the polymethacrylates such as polymethyl methacrylate, polyvinylbutyral, and cellulose acetate, all as used being in the form of any commercial emulsion of the plastic.

These particles as used in the emulsion are in part at least colloidal or microscopic in size and constitute the dispersed phase in a medium consisting largely or wholly of water or other liquid non-solvent for the hinder, the liquid containing any stabilizer or emulsifier that is commercially used to increase the stability or dispersibility of the binder material in the non-solvent. A suitable size is l0.05 micron for particles constituting at least half of the total weight of the binder material.

The particles of binder material contain the proportion, if any, of plasticizer required for non-brittleness of the binder material after drying. The plasticizer selected is one that is conventional for the plastic binder used. Examples of the plasticizers are dioctyl phthalate or adipate, dibutyl sebacate, tributoxyethyl phosphate, and butyl cresyl phosphate.

The temperature of softening of the binder material applied in the emulsion is chosen in accordance with the properties desired in the finished, plastic treated fabric. For treating goods that are to withstand boiling water temperature, I use plastic material that does not soften to the tacky condition at such temperature. For goods that will never be subjected to such an elevated temperature, the plastic chosen may have a lower softening point. For a given kind of plastic selected, I control the softening point by the proportion of plasticizer, as within the range 20%-50% of plasticizer on the weight of the unplasticized plastic. The greater the proportion of plasticizer, the lower the softening point.

All of the materials used in my process and article are chemically inert, that is, non-destructive of each other.

As to other proportions, I use a large proportion of water in the emulsion of the binder material, so that v evaporation of water from the applied material leaves than water.

spaces between adjacent particles of the binder. While this proportion of water may vary with the different natures of the selected binder material, I find a proportion of water within the range 30-70 parts of water to 100 of the total emulsion to be satisfactory. The proportion of water within the stated range is decreased as the total amount of applied plastic emulsion is made very low per square yard. The portion of water may be increased, on the other hand, as thicker layers or larger proportions of the emulsion are applied over the fabric.

The emulsion of binder material should be used in concentration and in amount applied to leave about 0.3-1 oz. of binder, dry weight, per square yard of fabric treated. This gives proper adherence of the metal flakes later applied and also leaves the desired spaces through the binder after the water is removed. The amount of the emulsion applied will in general be less, for a given permeability of the finished treated fabric, when the cloth treated is one that is closely woven, and the amount will be larger for relatively very open mesh fabrics. The amount of emulsion, being less than the saturation proportion, is less than that which, if applied, would make impossible, after drying, the blowing of cigarette smoke through the fabric with the mouth, the blowing through of smoke being evidence of preservation of permeability to air. The emulsion penetrates the surface only of the fabric. Subsequent drying leaves the originally emulsified plastic particles embedded or anchored in the surface of the fabric.

There is no need to use any non-solvent liquid other Besides its low cost, water is non-hazardous in use and entirely satisfactory in my process.

The invention will be further illustrated by description .in connection with the following specific examples of the practice of it.

Example 1 A woven cotton fabric (canvas) is given a light coating by roller 8 of a polyvinyl chloride emulsion known as Geon 576 latex. This contains 35 parts of dioctyl phthalate plasticizer for 100 of polyvinyl chloride, the

emulsion having been reduced in concentration before to the extent of at least through 200 mesh screen.

7 The mist spray shown in the drawing as applied by nozzle 36 and also the additional sheet material 35 are omitted in this example. This leaves the applied metal flakes uncovered over their surface away from the canvas.

The canvas, with the applied emulsion of the thermoplastic binding material and the subsequently applied aluminum flakes, is heated in the chamber 37 to a temperature of 8090 C. by radiant electric resistance heaters 38, cooled by passage through the chamber 46 supplied through 48 with a draft of cold air, and then wound at 54. Rollers 42 and 44 and the additional sheet 35 are omitted in this example. The product is finished otherwise as described above.

Example 2 The procedure of Example 1 is followed except that a light mist of the emulsion of binder material 14 is applied in the chamber 33. The amount of this mist is such that it does not give a continuous coating on the layer of aluminum particles after the subsequent drying operation, but leaves plastic with spaces therethrough for air breathing properties, these spaces communicating with the openings in the meshes of the canvas. This binder applied in the form of the mist leaves, on drying, spaced minute spots of plastic that adhere in part to the metal flakes and in part to the binder applied initially to the canvas.

Example 3 The procedure of Examples 1 or 2 above is followed with the substitution of any of the other binder materials disclosed herein, any of the other kinds of metal flakes, or paper for the polyvinyl chloride plastic, aluminum flakes, and canvas, respectively.

Example 4 The procedure of Example 2 is followed with the exception that an additional layer 35 of sheet material is applied against the freshly sprayed mist of binder material. This additional sheet material is provided in advance with spaced particles of thermoplastic material as described in my said copending application. These particles are inside in the laminate, soluble in the binder first applied, and, in the finished product, adhere the additional sheet over the metallized surface of the first sheet. The laminate is finished by passage between the compositing rollers 36, drier 37, between the pressing rollers 42, through the cooler 46, and to the winding 54. Fig. 4 shows a view of the thus made, laminated product.

Example 5 This example represents a modification of the invention illustrated in Examples 1-4.

In this example, the aluminum flakes 19, supplied by roller 18 to the fabric 2, are premixed with solid particles of a thermoplastic binder therefor. The thermoplastic binder is suitably of the same composition as that shown at 39. It is in the form of fine but macroscopic particles of the fineness, for instance, of coarse wheat flour or fine corn meal.

The proportion of the metal flakes to the binder material mixed therewith in the vessel 20 may vary considerably. Suitable proportions are 50-95 parts by weight of the binder for 100 parts of total weight of the mixed binder and metal flakes. In this particular example, I use 90 parts of the thermoplastic binder of the same kind as that shown at 39 for parts by Weight of flake aluminum.

The beater 30, tapping on the back of the cloth with the applied emulsion 16 and the subsequently applied mixture of aluminum flakes and macroscopic binder particles, dislodges and removes from the sheet those of the aluminum flakes and of the said macroscopic particles that are not in direct contact with the emulsion-wetted surface of the sheet.

In this example, the spray 39 of additional thermoplastic binder and also the plying with the additional sheet material 35 are omitted, the sheet 2 with the applied emulsion and premixed aluminum flakes and macroscopic particles of binder being passed directly between the drying and heating units 38 and the compression rollers 42 to the cooler 46 and to the winding mechanism.

Example 6 The procedure of Example 5 is followed except that the spray 39 of additional binder material and the laminating sheet 35 are applied and the product finished as previously described in connection with the laminating operation in Example 4.

Example 7 The procedure of Example 5 is followed with the following changes.

The premixed aluminum flakes and macroscopic solid particles of thermoplastic binder are applied from above as a layer over the sheet material previously treated with the dispersed binder 16. Then the direction of movement of the sheet is changed so that the said layer is on the underside of the moving sheet. Then the back of the sheet is tapped, so as to cause falling away of those of the said macroscopic particles and flakes not directly in contact with the dispersed, wet binder. The whole is then dried, warmed, rolled, and wound up, as described previously.

Such'equipment used in this example as is not illustrated in the drawing has already been described in my said Patent 2,603,575.

Products made as described reflect radiant energy, particularly when the metal used is aluminum. They permit passage of air and blowing of smoke through them. The layer of applied flake metal, although porous, is continuous over the crossovers of the strands of the fabric. The flake metal is especially adherent after application of the mist spray and subsequent processing and resistant to being brushed from the surface during use.

It will be understood that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.

What I claim is:

1. In making a metallized sheet, the process which comprises applying to a surface of a flexible, fibrous, air permeable sheet an aqueous dispersion of fine, undissolved particles of normally solid, non-volatile, thermoplastic resin binder material in limited proportion to avoid saturation of the sheet and to supply the said particles in spaced relationship to each other, then applying over the spaced particles of water-wet binder material a layer of heat reflecting metal flakes in uncovered condition, removing those of the applied flakes not adhered to the dispersed binder material, subjecting the sheet material so treated to an elevated temperature to volatilize the water present and soften the thermoplastic binder material, pressing the applied metal flakes upon the said sheet and the binder therein in softened condition, and then cooling the whole, the result being a sheet having the binder material adhered to the sheet and metal flakes adhered to the hinder, the flakes having uncovered reflecting faces, and the flakes defining between them spaces that are permeable to air.

2. The process of claim 1 in which the metal flakes as applied to the said sheet are interspersed with additional fine solid particles of thermoplastic binder material in dry form and in limited proportion not exceeding parts by weight for of total weight of the mixed binder and metal flakes so as to preserve air permeability of the finished product.

(References on following page) .Re mu es Ci d in h file of h s p en UNITED STATES PATENTS 8 Schramm Q July 15, 1952 Rand Mar. 10, 1953 Rand Mar. 10, 1953 FOREIGN PATENTS Great Britain Nov. 13, 19.24

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Claims (1)

1. IN MAKING A METALLIZED SHEET, THE PROCESS WHICH COMPRISES APPLYING TO A SURFACE OF A FLEXIBLE, FIBROUS, AIR PERMEABLE SHEET AN AQUEOUS DISPERSION OF FINE, UNDISSOLVED PARTICLES OF NORMALLY SOLID, NON-VOLATILE, THERMOPLASTIC RESIN BINDER MATERIAL IN LIMITED PROPORTION TO AVOID SATURATION OF THE SHEET AND TO SUPPLY THE SAID PARTICLES IN SPACED RELATIONSHIP TO EACH OTHER, THEN APPLYING OVER THE SPACED PARTICLES OF WATER-WET BINDER MATERIAL A LAYER OF HEAT REFLECTING METAL FLAKES IN UNCOVERED CONDITION, REMOVING THOSE OF THE APPLIED FLAKES NOT ADHERED TO THE DISPERSED BINDER MATERIAL, SUBJECTING THE SHEET MATERIAL SO TREATED TO AN ELEVATED TEMPERATURE TO VOLATILIZE THE WATER PRESENT AND SOFTEN THE THERMOPLASTIC BINDER MATTERIAL, PRESSING THE APPLIED METAL FLAKES UPON THE SAID SHEET AND THE BINDER THEREIN IN SOFTENED CONDITION, AND THEN COOLING THE WHOLE, THE RESULT BEING A SHEET HAVING THE BINDER MATERIAL ADHERED TO THE SHEET AND METAL FLAKES ADHERED TO THE BINDER, THE FLAKES HAVING UNCOVERED REFLECTING FACES, AND THE FLAKES DEFINING BETWEEN THEM SPACES THAT ARE PERMEABLE TO AIR.

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