MXPA06000052A - Methods to produce gel sheets - Google Patents

Abstract

The present invention provides various methods for producing gel sheets (46) in a continuous fashion. The embodiments of the present invention help reduce the time of producing gel sheets (46) that is suitable for industrial manufacturing. Such gel sheets (46) are used in manufacturing aerogel blankets used in a variety of applications including thermal and acoustic insulation.

Description

METHODS TO PRODUCE GEL CANVAS CROSS REFERENCE WITH RELATED APPLICATIONS This application claims priority, and incorporates the entire pending US provisional patent application. Serial number 60 / 482,359, which is entitled "Methods for producing gel linens" (Methods for producing Gel Sheets), and which was submitted on June 24, 2003.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to the preparation of gel sheets impregnated with solvents in a continuous manner. These gel canvases are used in the manufacturing of airgel blankets, airgel composites, airgel monoliths and other products based on airgel.

DESCRIPTION OF THE BACKGROUND TECHNIQUE The term aerogels describes a class of material based on its structure, mainly of low density, open cell structures, large surface areas (often 900 m2 / g or higher) and pore sizes at sub-nanometer scale. . The technologies of P06 / 006AAI Extraction of supercritical and subcritical fluids is commonly used to extract fluid from fragile cells in the material. A variety of different airgel compositions are known and can be organic and inorganic. Inorganic aerogels are usually based on metal alkoxides and include materials such as silica, carbides and alumina. Organic aerogels include, among others, urethane aerogels, resorcinol formaldehyde aerogels and polyimide aerogels. It is widely considered that low density airgel materials (0.01-0.3 g / cc) are the best thermal insulators, better than the best rigid foams with thermal conductivities of 10-15 mW / mK and below 100 ° F a the atmospheric pressure. Aerogels function as thermal insulators mainly by minimizing conduction (low density, tortuous path for heat transfer through conductive nanostructures), convection (very small pore sizes minimize convection) and radiation (dopants of absorption or diffusion of IR are easily dispersed throughout the airgel matrix). Depending on the formulation, aerogels can function adequately at cryogenic temperatures at -550 ° C and above. Airgel materials also show many other P06 / 006AAI interesting acoustic, optical, mechanical and chemical properties that make them very useful. Low density insulating materials have been developed to solve various insulation problems in term of application where the core of the insulation experiences considerable compressive forces. For example, polymeric materials with hollow glass microspheres have been formed to create syntactic foams, which are usually materials that are resistant to compression and very rigid. Syntactic materials are well known as insulators for submarine pipelines and pipelines and for support equipment. The syntactic materials are relatively inflexible and have a high thermal conductivity compared to flexible airgel composites (fiber reinforced airgel matrices). Aerogels can be formed from flexible gel precursors. Several flexible layers, including flexible aerogels reinforced with fibers, can be easily combined and shaped to obtain preforms that when compressed mechanically along one or more axes, obtaining compressively strong bodies along any of these axes. Airgel bodies that are compressed in this way exhibit much better thermal insulation value than syntactic foams. Methods to produce these P06 / 006AAI materials quickly facilitate their use on a large scale in submarine pipelines and pipelines as external insulation. Conventional methods for the production of composite gel canvases reinforced with fibers and / or gel cloths formed via the sol-gel chemistry described in the patent and scientific literature invariably involve discontinuous molding. In this description the term discontinuous molding is defined as the action of catalyzing a full volume of sol to simultaneously induce gelation throughout that volume. The techniques of gel formation are well known by those who have training in the technique, examples include adjusting the pH and / or temperature of a dilute metal oxide sol to a point where gelation occurs (R. K. Iler, Colloid Chemistry of Silica and Silicates, 1954, Chapter 6; R. K. Iler, The Chemistry of Silica, 1979, chapter 5, C. J. Brinker and G. -. Scherer, Sol-Gel Science, 1990, chapters 2 and 3). U.S. Pat. Do not . 6, 068, 882 (Ryu) discloses an example of fiber reinforced airgel composite material that can be put into practice with the embodiments of the present invention. The airgel composite precursor materials which are considered to be preferred and which are employed in the present invention are P06 / 006AAI those similar to Cryogel®, Pyrogel® or Spaceloft ™ sold by Aspen Aerogels, Incorporated. The US incorporated patent Do not . 5,306,555 (Ramamurthi et al.) Discloses an airgel matrix composite of a crude airgel with dispersed fibers within the crude airgel and a method for preparing the airgel matrix composite.

SUMMARY OF THE INVENTION This invention discloses continuous and semi-continuous sol-gel molding methods which are considerably better than conventional batch sol-gel methods for the manufacture of gel canvases, flexible fiber-reinforced gel cloths and rolls of binder materials. gel compounds. More specifically, the invention describes methods for the continuous combination of a solution of low viscosity of a sol and an agent (thermal catalyst or chemical catalyst) which induces gel formation and which forms a gel canvas on a moving element. as, for example, a conveyor belt with edges defining the volume of the gel canvas formed by dispersing the catalyzed sol at a predetermined effective rate to allow gelation to occur on the moving element. The sun includes a material P06 / 006AAI inorganic, organic or a combination of inorganic / organic hybrid materials. Inorganic materials include zirconia, yttria, hafnium, alumina, titania, ceria and silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride and any combination of the above. Organic materials include polyacrylates, polyolefins, polystyrenes, polyacrylonitriles, polyurethanes, polyunsaturates, polyfurfural alcohols, phenol-furfuryl alcohol, formaldehydes of melanin, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, dialdehyde-polyvinyl alcohol, polyanurates, polyacrylamides, various epoxy, agar, agarose and any combinations of the above. Even more specifically, the methods describe the formation, in a continuous or semicontinuous manner, of monolithic gel liners or fiber reinforced gel composite materials having two parts, i.e., reinforcing fibers and a gel matrix, wherein the reinforcing fibers are in the form of a foamed fibrous structure (ie, batt), preferably based on silica or thermoplastic polyester fibers, and more preferably in combination with randomly distributed short individual fibers. (microfibers). The wadding or mat material is introduced over the moving element for its P06 / 006AAI combination with the sun catalyzed before gelation. Still further, when reinforcing a gel matrix with foamed wadding material, particularly a continuous nonwoven wadding composed of very few denier fibers, when the resulting composite material when dried in an airgel or xerogel product by solvent extraction , maintains thermal properties similar to those of a monolithic airgel or xerogel in a much stronger and more durable way. The diameter of the fibers used is in the range of 0.1-10,000 microns. In some cases, nanofibers in the range of 0.001 to 100 microns are employed in the gel-reinforcing action. In addition to the fiber batt, crimped fibers can be distributed throughout the gel structure. Even more specifically, the methods describe methods for continuously or semi-continuously forming gel composites by introducing a zone of energy dissipation into the moving conveyor. The gelation of the catalyzed sol can be intensified with a chemical or energy dissipation process. For example, a controlled flow of electromagnetic radiation (ultraviolet, visible, infrared, microwave), acoustic (ultrasound) or particle radiation across the width of a volume of sunlight can be introduced.

P06 / 006AAI movement contained by a conveyor belt to induce sufficient crosslinking of the polymers contained within the sol to achieve a gel point. The flow, the point and the radiation area can be controlled along the transport apparatus for when a certain section of the gel reaches the end of the conveyor. In this way, the properties of the gel can be controlled in a novel manner to an extent impossible with discontinuous molding methods. In addition, another moving element can be employed in the opposite direction with respect to the first moving element in order to obtain the shape of the upper portion of the gel canvases. Still more specifically, using the method of the present invention, a roll of gel composite that is co-blended or co-wound with a porous flow layer that facilitates the extraction of solvents using methods that process supercritical fluids can be formed. in a very small pressure area. This is done by implanting a predetermined amount of catalysed sol in a coiled coiled fiber preform with an impermeable separating layer, by gelling the implanted coil, followed by unwinding of the composite gel article, removal of the impermeable layer and rewinding. of the composite material P06 / 006AAI of flexible gel, of incompletely cured body, with a porous separating layer. The method described in this invention offers a greater advantage in the action of intensifying the production rate of gel composites in as small an area as possible. Still more specifically, a method is described for producing gel liners in a continuous manner in which gel linens are produced by any of the aforementioned methods and wound onto a plurality of layers. This is a novel and effective way to produce gel linens for effective drying operations. In another aspect, an optional spacer material is co-rolled with the gel liners. Such material may have a permeable or impermeable nature. Depending on the permeability of the separating material, a person can obtain a favorable flow pattern in a subsequent drying process. The separator material also provides flow paths for the subsequent flows of syllable (curing) to easily pass through. In the drying process they also help to confirm flow paths that effectively reduce the thickness of the gel canvas to be extracted in a radial direction. These and still other embodiments of the present invention are described in more detail below. They are P06 / 006AAI many the advantages of the methods described in this invention to process composite canvases reinforced with fibers and monolithic canvases in a continuous or semi-continuous manner over the methods previously described. For example, gel articles can be molded in a continuous or semi-continuous manner as long as all the components are fed to the apparatus in the proper proportion. As a result, large volumes of material can be molded into a smaller production area than that used with traditional batch molding that requires molds to be filled, and curing can be allowed prior to solvent extraction to make Airgel or xerogel materials. Easily long, continuous canvases of flexible fiber-reinforced gel material are molded employing the methods of this invention since the combined processing of molding and rolling allows a single molding surface to be continuously used again within a small area of production. When rolls of gel are cast discontinuously followed by roll-to-roll processing to place porous flow layers between the layers of the gel material, the printing area of the production is further reduced, which increases the production capacity and what potentially decreases production costs in P06 / 006AAI comparison with the discontinuous molding of flat canvases.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a method for producing fiber reinforced gel liners using a counterrotating conveyor belt. Figure 2 illustrates a method for producing fiber reinforced gel canvases using a simple rotating conveyor belt. Figure 3 illustrates a method for producing fiber reinforced gel liners employing a counter-rotating conveyor belt with an additional cutting process. Figure 4 illustrates a method for producing fiber reinforced gel canvases using simple rotation conveyor belt with an additional cutting process. Figure 5 illustrates the general flow diagram of the mixed catalyst sun before molding. Figure 6 illustrates a further embodiment with the soldering of the catalysed sol towards a preformed roll including separating layers. Figure 7 illustrates a further embodiment for producing gel linens by implanting a gelation zone. Figure 8 illustrates an additional modality for P06 / 006AAI produce gel canvases with one or more separating layers.

DETAILED DESCRIPTION OF THE INVENTION The invention or inventions described herein are directed to producing flexible blanket-like composite and nanostructured monolith gel materials impregnated with solvents. These materials provide nanoporous airgel bodies after all solvents in mobile phase are extracted using a hypercritical solvent extraction process (drying of supercritical fluids). For example, the processes described in this invention will offer considerably higher production capacities for shaping grit gel canvases or gel composite articles wound in a shape factor which will facilitate the removal of solvents in a subsequent process of supercritical fluids. The first method broadly describes a conveyor-based system that employs at one end a supply of a low viscosity catalyzed sol mixture and a system for cutting and transporting shaped monolithic liners (defined herein as only a solid ceramic or polymer, with no fibers added) of gel material impregnated with solvents in a system for additional chemical treatment. The second method describes P06 / 006AAI a system based on a conveyor that employs at one end a supply of a low viscosity catalyzed sol mixture and a system for cutting and transporting composite gel canvases reinforced with solvent impregnated fibers in a winding system (with and without a layer of porous separating flow) to produce a shape factor ready for further treatment before the extraction of supercritical fluids. The third method describes a direct transfer process from roll to roll between two cartridges in which the first houses a direct reaction of the "gel on a roll" followed by the unwinding and re-rolling of the gel with a layer of porous separating flow to prepare the Form factor for additional treatment before supercritical extraction. The three methods can be used in combination with controlled energy delivery methods to facilitate time control of the gelation and the strength of the shaped green bodies. Energy can be used in the form of ultrasound, heat and various forms of radiation or to induce gelation from a sun mixture prepared in addition to the classical methods of chemical catalysis (such as, for example, a change in pH in the pH of the stable sun towards a value that facilitates gelation). The matrix materials described in this invention are best derived from a sol-gel processing, from P06 / 006AAI preference are composed of polymers (inorganic, organic, or inorganic / organic hybrids) that define a structure with very small pores (in the order of billionths of a meter). Fibrous materials can be added before the reinforcement point by gelation with polymers of the matrix materials described in this invention. Reinforcement with preferably preferred fibers is a fluffy fibrous structure (wadding or weft), but may also include randomly oriented short individual microfibers and woven or nonwoven fibers. More particularly, reinforcements with preferred fibers are based on organic fibers (e.g., thermoplastic polyester, high strength carbon, aramid, high strength oriented polyethylene), inorganic at low temperatures (several metal oxide glasses, for example , glass E) or refractory (for example, silica, alumina, aluminum phosphate, aluminosilicate, etc.). The thickness or diameter of the fibers used in the embodiments of the present invention is in the range of 0.1 to 10,000 microns, and preferably in the range of 0.1 to 100 microns. In another preferred embodiment, nanostructure fibers as small as 0.001 microns are used to reinforce the gel. Typical examples include carbon nonofibers and carbon nanotubes with such small diameters P06 / 006AAI as 0.001 micras. Gel sheets impregnated with solvents can be formed by combining a ceramic solid (for example, silica) and a solvent in mobile phase (for example ethanol) on a conveyor by continuous injection of a catalyst phase into a sun phase and dispersing the catalyzed mixture. on a moving conveyor. This type of material will find use in insulating transparencies such as, for example, windows with double glazing in buildings. Since these gel materials are usually rigid and inflexible when they are composed of a cross-linked polymer matrix material with intercalated solvent (gel solvent) without fiber reinforcement, it is necessary to handle these materials as they are molded, in case of be molded continuously. If the conveyor has molded edges that retain the volume, then the gel can be molded directly on the surface of the conveyor. If the conveyor has molds on itself, then the volumes of the molds can be filled continuously with the sun continuously catalyzed. Suitable materials for the formation of inorganic aerogels are oxides of most metals that can form oxides such as, for example, silicon, aluminum, titanium, zirconia, hafnium, yttria, vanadium, etc. There is a particular preference for P06 / 006AAI the genes formed mainly by alcoholic solutions of hydrolyzed silicate esters for reasons of their easy availability and low cost (alcogel). Organic aerogels can be produced from polyacrylates, polystyrenes, polyacrylonitriles, polyurethanes, poly-imides, polyfurfural alcohol, phenol-furfuryl alcohol, formaldehydes of melanin, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, dialdehyde-polyvinyl alcohol, polyanurates, polyacrylamides, various epoxy, agar, agarose and the like (see for example, CS Ashley, CJ Brinker and DM Smith, Journal of Non-Crystalline Solids, volume 285,2001). In a preferred embodiment of the methods of this invention, energy dissipation is employed through a portion of the volume of sol at a specific site of a conveyor apparatus used for gel molding. By controlling the area of the catalyzed sun that is exposed to heat or specific radiation (for example, ultrasonic, X-ray, electron probe, ultraviolet, visible, infrared, microwave, gamma rays), a phenomenon of gelation can be induced in a specific point of a conveyor device. It is advantageous to control the time of the gelation point with respect to the speed of the conveyor so that the material has the time P06 / 006AAI suitable to be cured and strengthened before any mechanical manipulation at the end of the conveyor. Although the diffusion of the polymer chains and the subsequent growth of the solid network are considerably slow within the viscous gel structure after the gelation point, it is essential to maintain the original gel liquid (mother liquor) for a period of time after the gelation in order to obtain an airgel that has the best thermal and mechanical properties. This period of time in which the gel is "cured" without disturbance is called "syneresis". The conditions of syneresis (time, temperature, pH, solids concentration) are important for the quality of the airgel product. Gels are a class of materials formed by fixing a mobile phase of interstitial solvent within the pores of a solid structure. The solid structures may be composed of inorganic, organic polymeric materials or inorganic / organic hybrid polymeric materials that develop a pore morphology in direct in relation to the gelation method, solvent-polymer interactions, polymerization and crosslinking rate, solids content , catalyst content, temperature and other various factors. It is preferred that the gel materials are P06 / 006AAI conform from precursor materials, including various fiber reinforcing materials that confer flexibility to the shaped composite, in a continuous or semi-continuous manner in the form of canvases or rolls of canvases so that the interstitial solvent phase can be easily removed by a process of extracting supercritical fluids to produce an airgel material. By maintaining the solvent phase above the critical pressure and temperature during the entire solvent extraction process, or at least in the final part of said process, large capillary forces originating from the evaporation of liquids from very small pores are not created. that cause the shrinkage and collapse of the pores. Typically aerogels have gross densities (of about 0.15 g / cc or lower, preferably from 0.03 to 0.3 g / cc), very high surface areas (typically from about 300 to 1,000 m2 / g and above, preferably from about 700 to 1000 m2 / g), a high porosity (of about 90% and above, preferably greater than about 95%), and a relatively large pore volume (of about 3 iriL / g, preferably of about 3.5 mL / g and higher). The combination of these properties in an amorphous structure confers the lowest thermal conductivity values (from P06 / 006AAI 9 to 16 m / m-K at 37 ° C and at 1 atmosphere pressure) to any solid coherent material. The methods for molding monolithic gel material and compound described in the present invention comprise three distinct phases. The first is the mixing of all the constituent components (solid precursor, dopants, additives) in a low viscosity sol whose mixture can be dispersed in a continuous manner. The second involves dispersing the mixed sun on a moving conveyor mold which may have a synchronized counter-rotation upper band to form a molded upper surface. The second phase may also include the introduction of heat or radiation to the ungelled sol into a defined area of the moving conveyor to induce gelation or to modify gel properties such as, for example, the gel modulus, resistance to the tension or the density. The third phase of the process of the present invention involves cutting the gel and transporting the monolithic gel canvases to a post-processing area, or co-winding a flexible, fiber-reinforced gel composite material, with a flexible porous flow layer to generate a particularly preferred form factor of the material. The rolls formed of the gel composite and the flow layer are particularly feasible P06 / 006AAI to perform the interstitial solvent removal using supercritical processing methods. An example of the preferred gel molding method is shown in Figure 1, which employs a conventional chemically catalysed sol-gel process in combination with a moving conveyor with a counter-rotating molding capability. The nanoporous fiber reinforced gel composite material can be wound mechanically with or without a porous flow layer, as shown in Figure 1. Figure 2 shows the same process that employs a moving conveyor belt with only a single surface molding (a lower band that continuously rotates with molded sides). Figure 3 shows how monolithic gel canvases, formed from polymeric sol (without having added fiber reinforcing structures) can be formed continuously by depositing a catalyzed sol solution on a moving conveyor, and Figure 4 illustrates the same procedure with the exception that a strategy of molding the counterrotating conveyor is shown. The sun materials used in this invention are mixed and prepared, often by mixing them with a chemical catalyst, before being deposited on the moving conveyor, as shown in the block diagram of Figure 5. In Figure 6, P06 / 006AAI shows a related, but alternative embodiment of the present invention, in which a fiber and a separating layer preform roll are infiltrated with a sol, and then the initial gelation is performed, unrolled to separate the composite material from the layer waterproof and then re-rolled with a permeable layer to prepare additional chemical processing. The gel matrix of the preferred precursor materials for the present invention can be organic, inorganic or a mixture thereof. The sol materials can be catalyzed to induce gelation by methods known to those skilled in the art: examples include adjusting the pH and / or temperature of a dilute metal oxide sol to a point where gelation occurs (The following documents are incorporated herein) this description as reference: RK Iler, Colloid Chemistry of Silica and Silicates, 1954, chapter 6, RK Iler, The Chemistry of Silica, 1979, chapter 5, CJ Brinker and GW Scherer, Sol-Gel Science, 1990, chapters 2 and 3 ). Suitable materials for the formation of inorganic aerogels are oxides of most metals that can form oxides such as, for example, silicon, aluminum, titanium, zirconia, hafnium, yttrium, vanadium and the like. Particularly preferred gels are those formed primarily by alcoholic solutions of P06 / 006AAI hydrolyzed silicate esters due to its easy availability and low cost (alcogel). Those skilled in the art also know that organic aerogels can be made from organic polymer materials including polyacrylates, polystyrenes, polyacrylonitriles, polyurethanes, polyamides, EPDM and / or solutions of polybutadiene gum, polyimides, polyfurfural alcohol, phenol-alcohol Furfuryl, formaldehyde melanin, formaldehyde resorcinol, cresol formaldehyde, phenol formaldehyde, dialdehyde - polyvinyl alcohol, polyanurate, polyacrylamide, various epoxy, agar, agarose and the like (see for example, C. S. Ashley, C. J. Brinker and D. M.

Smith, Journal of Non-Crystalline Solids, volume 285, 2001). Various forms of electromagnetic, acoustic or particle radiation sources can be employed to induce gelation of the sun precursor materials on the moving conveyor. The literature contains several examples in which to induce gelation a sun material can be exposed to heat, ultrasonic energy, ultraviolet light, gamma radiation, electron beam radiation, and the like. It is advantageous to control the properties of the gel as well as those of the dry material of airgel or xerogel P06 / 00SAAI of energy dissipation (heat, acoustics, radiation) in a fixed area of the conveyor apparatus, so that an accumulation of moving sol material interacts with a controlled energy flow for a fixed period of time. This process is illustrated in Figure 7. In general terms, the main synthetic route for the formation of an inorganic airgel is the hydrolysis and condensation of an appropriate metallic alkoxide. Most suitable metal alkoxides are those having about 1 to 6 carbon atoms, preferably about 1 to 4 carbon atoms, in each alkyl group. Specific examples of such compounds include tetraethoxysilane (TEOS), tetraethoxysilane (TMOS), tetra-n-propoxysilane, aluminum isopropoxide, aluminum sec-butoxide, cerium isopropoxide, hafnium tert-butoxide, magnesium isopropoxide and aluminum, yttrium isopropoxide, titanium isopropoxide, zirconia isopropoxide, and the like. In the case of silica precursors, these materials can be hydrolyzed and partially stabilized at a low pH as polymers of polysilicic acid esters such as, for example, polydiethoxysiloxane. These materials are available in the market in alcoholic solution. The pre-polymerized silica precursors are considered especially preferred for P06 / 006AAI the processing of the gel materials described in this invention. In this description the action of inducing the gelation of sol materials of metal oxides in alcoholic solutions is called the alcogel process. Those skilled in the art understand that gel materials formed using the sol-gel process can be derived from a wide range of metal oxides or other polymer-forming species. It is also well known that sol materials can be doped with solids (IR opacifiers, sintering retardants, microfibers) that influence the physical and mechanical properties of the gel product. Suitable amounts of this type of dopants generally range from about 1 to 40% by weight of the finished composite, preferably from about 2 to 30% by employing the molding methods of this invention. The main variables in the formation process of inorganic airgel include the type of alkoxide, pH of solution and alkoxide / alcohol / water ratio. The control of the variables can allow the control of the growth and aggregation of the matrix species throughout the transition from the "sun" state to the "gel" state. Although the properties of the resulting aerogels are strongly affected by the pH of the precursor solution and the molar ratio of the reagents, in the present invention it can be P06 / 006AA? use any pH and any molar ratio that allow the formation of gels. In general terms, the solvent should be a lower alcohol, that is, an alcohol having 1 to 6 carbon atoms, preferably 2 to 4 carbon atoms, although, as is known in the art, it can be used other liquids Examples of other useful liquids include, but are not limited to: ethyl acetate, ethyl acetoacetate, acetone, dichloromethane, and the like. For convenience, the alcogel route for the formation of inorganic silica gels and composite materials is then used in order to illustrate how to create the precursors used by the invention, although this is not intended to limit the present invention to any type of gel. The present invention can be applied to other gel compositions. Alternatively, other methods of gel induction and sun preparation can be used in order to prepare a precursor gel article making use of the processing methods of this invention, but chemical methodologies that allow obtaining the density are preferred. lowest and / or the best thermally insulating articles. For example, a water-soluble precursor of basic metal oxide can be neutralized with an aqueous acid in a continuous manner, P06 / 006AA1 it can deposit on a moving conveyor belt, as shown in Figures 1 and 2, and can be induced to make a hydrogel on the conveyor belt. Sodium silicate has been widely used as a hydrogel precursor. The salt byproducts of the silicic acid precursor can be removed by ion exchange and / or by washing gels subsequently formed with water after the formation and mechanical manipulation of the gel of the gel. After identification of the gel material to be prepared using the methods of this invention, a suitable solution of metal-alcoholic alkoxide is prepared. The preparation of airgel forming solutions is well known in the art. See for example, S. J. Teichner et al, Inorganic Oxide Airgel, Advances in Colloid and Interface Science, Vol. 5.1976, p. 245-273, and L. D. LeMay, et al., Lo-Density Microcellular Materials, MRS Bulletin, Vol. 15, 1990, p. 19. For the production of silica gel monoliths and silica gel composite materials reinforced with fibers useful in the manufacture of silica airgel material, the usually preferred ingredients are tetraethoxysilane (TEOS), water and ethanol (EtOH). The preferred proportion of TEOS to water is approximately 0.2-0.5: 1, the preferred proportion of TEOS to EtOH is P06 / 006 I about 0.02-0.5: 1, and the preferred pH is about 2 to 9. The natural pH of a solution of ingredients is about 5. While any acid can be used to obtain a low pH solution, they are currently considered preferred. the preferred acids HCl, H2SO4 or ET. To generate a higher pH, NH40H is the preferred base. For the purposes of this patent, a sponge wadding is defined as a fibrous material that exhibits the properties of bulkiness and some resilience (with or without full recovery of bulkiness). The preferred form is a soft weft of this material. The use of a sponge wadding material minimizes the baseless airgel volume while avoiding considerable degradation of the thermal performance of the airgel. The term "batt" preferably refers to layers or canvases of a fibrous material, which is commonly used to serve as a quilt or fill or packaging liner or as a thermal insulation blanket. Wadding materials having some tensile strength are advantageous for their introduction into the conveyor and molding system, but are not necessary. Load transfer mechanisms can be used in the process of introducing delicate wadding materials into the conveyor region prior to P06 / 006AAI infiltration with a flow of prepared sun. The fibrous materials suitable for the formation of sponge batting as well as stress-strengthening layers oriented in the x-and-planes include any fiber-forming material. Particularly suitable materials include: glass fibers, quartz, polyester (PET), polyethylene, polypropylene, polybenzi-idazole (PB1), polyphenylenebenzo-bisoxasol (PBO), polyetheretherketone (PEEK), polyarylate, polyacrylate, polytetrafluoroethylene (PTFE), polyethylene metaphenylene diamine (Nomex), poly-paraphenylene terephthalamide (Keviar), ultra high molecular weight polyethylene (UHMWPE, ultra high molecular weight polyethylene), for example, SpectraTM, novoloid resins (Kynol), polyacrylonitrile (PAN), PAN / carbon, and carbon fibers. Figure 1 illustrates a method that produces fiber reinforced gel sheets in a continuous or semi-continuous manner using a catalyst and sun dispersant mixing system and a counterrotating conveyor molding apparatus. Composite gel linens can be produced in rolled form if they are mechanically wound at the end of the band. The internal numbers of figure correspond as follows: the number 11 is a stable sun precursor solution, the number 12 is a catalyst to induce the gelation of the P06 / 006AAI Sun when added in an appropriate amount under controlled conditions, number 13 indicates the flow control positions, number 14 is a static mixer, number 15 is the position in the fluid mixing system where the sun has completely mixed with the catalyst, number 16 is a scraper / lubrication device (optional), number 17 is a fibrous batting material (can be found on individual canvases or rolls that are fed into the unit), number 18 indicates two counter-rotating band units forming the molding surfaces along whose length the gelation occurs before the winding unit indicated with the numeral 19. Figure 2 illustrates a method that produces gel cloths reinforced with fibers of a continuous or semi-continuous manner using a catalyst and sun dispersant mixing system and a counterrotating conveyor molding apparatus. Composite gel linens can be produced in rolled form if they are mechanically wound at the end of the band. The internal figure numbers correspond as follows: the number 21 is a stable sun precursor solution, the number 22 is a catalyst to induce the gelation of the sun when it is added in an appropriate amount under controlled conditions, the number 23 indicates the positions P06 / 006AAI of flow control, the number 24 is a static mixer, the number 25 is the position in the fluid mixing system where the sun has completely mixed with the catalyst, the number 26 is a scraper / lubrication device ( optional), the number 27 is a fibrous batting material (can be found on individual canvases or rolls that are fed into the unit), the number 28 indicates two counter-rotating band units forming the molding surfaces along whose length happens the gelation before the winding unit indicated with the number 29. Figure 3 illustrates a method that produces gel canvases in a continuous or semi-continuous manner that employs a system of mixing catalyst and sun dispersant and a molding apparatus of counterrotating conveyor belt. The internal numbers of the figure correspond as follows: the number 30 is a stable sun precursor solution, the number 31 is a catalyst for inducing the gelation of the sun when it is added in an appropriate amount under controlled conditions, the number 32 indicates the flow control positions, the number 33 is a static mixer, the numbers 34 and 35 are two units of counter-rotation band which forms molding surfaces along whose length the gelation occurs before the P06 / 006AAI gel linen cutting unit indicated with the number 36. The individual gel liners (37) are then ready for further processing. Figure 4 illustrates a method that produces gel liners in a continuous or semi-continuous manner employing a catalyst and sun dispersant mixing system and a conveyor belt molding apparatus. The internal figure numbers correspond as follows: the number 40 is a stable sun precursor solution, the number '41 is a catalyst to induce the gelation of the sun when added in an appropriate amount under controlled conditions, the number 42 indicates the flow control positions, the number 43 is a static mixer, the number 44 is a conveyor belt mold along whose length the gelation proceeds before the gel linen cutting unit indicated with the number 45. individual gel canvases (46) then they are ready for further processing. Figure 5 illustrates the general flow diagram for the mixing process of a sol material and a catalyst in a mixing zone before molding (deposit) to a controlled ratio on a transoporter apparatus in a continuous manner. Figure 6 illustrates an alternative molding method involving a preformed roll (60) of layer P06 / 006AAI separator and fibers in a container (61) that is infiltrating with sol (62), and then the initial gelation (63) takes place, the roll is also shown unrolling (64) to separate the gel composite from the waterproof layer (65) and subsequently rerolled with a permeable layer (66) to form a gel composite / flow layer roll (67) in order to prepare it for further chemical processing. Or, the infiltrated preform of the sun can be dried directly with a separating layer present therein and unrolling it. Figure 7 illustrates a method that produces fiber-reinforced gel sheets in a continuous or semi-continuous manner employing a sun-dispersing system and a single conveyor-molding apparatus. The gelation is induced in a designated area of the conveyor by exposing the sun to heat or radiation. The internal figure numbers correspond as follows: the number 70 is a stable sun precursor solution, the number 71 is a catalyst to induce the gelation of the sun when it is added in an appropriate amount under controlled conditions, the number 72 indicates the Flow control positions, number 73 is a static mixer, number 74 is the position in the fluid mixing system where the sun has completely mixed with the catalyst, number 75 is P06 / 006AAI a fibrous batting material (can be found on individual canvases or rolls that feed into the unit), the number 76 is an energy device in the sun or gel to alter its properties (for example, inducing cross-linking), the number 77 indicates a conveyor belt unit forming a surface along whose length the gelation occurs before the winding unit indicated by the numeral 78. Figure 8 illustrates another embodiment of the present invention, where the sun material is dispersed over a conveyor belt and it is allowed to return gel as the conveyor belt travels a specific distance (corresponding to a specific residence time) and rolled on a mandrel. While the gel sheet is rolled, a permeable separating layer is co-rolled with the gel sheet, so that either of the two layers of gel sheets are separated with the separating layer. Optionally, this separating layer could be waterproof. The rolled gel linen unit is further dried in a supercritical dryer. The separating layer provides effective flow paths during supercritical extraction / drying. If the impermeable separating layer is used, it channels the flow of the extraction fluid in the axial direction. Depending on the requirements that arise from the composition of the canvas of P06 / 006AAI gel, an impermeable or permeable separating layer is employed to provide the necessary flow patterns in the supercritical extract / dryer. In the following specific examples, additional details or some other explanation of the present invention can be discovered, which describe the manufacture of mechanically densified airgel composites according to the present invention and evaluate the results generated therefrom. All parts and percentages are by weight, unless otherwise specified.

Example 1 Twenty gallons of silica sol produced by hydrolysis of a 20% TEOS solution in ethanol (at pH 2 at room temperature for 24 hours) are introduced into a stainless steel vessel equipped with a connected bottom drain. to a flow pump and a flowmeter. A separate vessel also equipped the bottom with a drain, pump and a flow meter is filled with an excess of ammoniated ethanol (1%). The two separate fluids are combined in a fixed ratio using the flow meters using the static mixer and are deposited through the dispensing head on a flat surface of the moving conveyor. The band P06 / 006AAI The conveyor has flexible edges welded to the surface (in this example a 38"spacing is used, but it can be almost any practical width), so that the delivered sun is contained in volume, a tensioner roller comes into contact with the The front surface of the moving conveyor belt avoids the backscattering of the low viscosity sol.The speed of the belt is adjusted so that the gelation front within the mixed sol (defined as the fixed position along the conveyor table in the which the sun no longer flows freely, taking a quality similar to rubber) appears halfway along the length of the table, a gelation time ratio with respect to the syneresis time of 1: 1 is preferred, but no problems can vary between 2: 1 and 1: 5. As the gelled sol reaches the end of the table, each silica gel plate is cut by its width and transferred onto a load-bearing plate in a bath of alcohol for further processing.

Example 2 Twenty gallons of silica sol produced by hydrolysis of a 20% TEOS solution in ethanol (at pH 2 at room temperature for 24 hours) are introduced into a stainless steel vessel equipped with P06 / 006AAI a bottom drain connected to a flow pump and a flow meter. A separate vessel also equipped the bottom with a drain, pump and a flow meter is filled with an excess of ammoniated ethanol (1%). The two separate fluids are combined in a fixed ratio using the flow meters using the static mixer and are deposited through the dispensing head on a flat surface of the moving conveyor (a width of 38"between the flexible edges). Polyester wadding (38 inches wide) with an approximate thickness of 0.5"is fed to the conveyor system at the same linear speed of the belt. A tensioner roller that comes in contact with the front surface of the moving conveyor belt prevents back-diffusion of the low viscosity sol, and another tensioner roller on the front of the deposit point of the sun is used to assist in the infiltration of the sun in the Wadding material. The speed of the band is adjusted so that the gelation front within the mixed sun (defined as the fixed position along the conveyor table in which the sun no longer flows freely, taking a rubbery quality) appears in half along the length of the table. For flexible gel materials, a gelation time ratio with respect to the syneresis time of 1: 1 is preferred, but without problems it can vary between 2: 1 and 1: 2.

P06 / 006AAI As the gelled sol reaches the end of the table, the flexible gel composite material is wound onto a cylindrical mandrel. A perforated polyethylene mesh is used to maintain the tension of the roll as it is formed. The roll is then readied for further processing and can be transferred using the mandrel as a load-bearing instrument.

EXAMPLE 3 Twenty gallons of silica sol produced by hydrolysis of a 20% solution of TEOS in ethanol (at pH 2 at room temperature for 24 hours) are introduced into a stainless steel vessel equipped with a bottom drain connected to the tank. a flow pump and a flowmeter. The silica sol material is pumped to a fixed ratio through the dispensing head on a flat surface of the moving conveyor (a width of 38"between the flexible edges). A roll of polyester wadding (38 inches wide) with an approximate thickness of 0.5", the conveyor system is fed at the same linear speed of the belt, before the point of deposit of the sun. A tension roller that comes in contact with the front surface of the moving conveyor belt prevents back diffusion of the low viscosity sol, and another tension roller in the front of the point of P06 / 006AAI Sun deposit is employed to assist in the infiltration of the sun into the wadding material. At the midpoint of the conveyor apparatus, configurations of ultrasound transducers coupled to the bottom of the belt are created through a lubricating gel. The speed of the band and the frequency and ultrasonic energy are adjusted so that the gelation front within the mixed sun appears approximately halfway along the length of the table. As the gelled sol reaches the end of the table, the flexible gel composite material is wound onto a cylindrical mandrel. A perforated polyethylene mesh is used to maintain the tension of the roll as it is formed. The roll is then readied for further processing and can be transferred using the mandrel as a load-bearing instrument.

EXAMPLE 4 Twenty gallons of silica sol produced by hydrolysis of a 20% solution of tetramethylorthosilicate (TM0S) in ethanol (at pH 2 at room temperature for 4 hours) are introduced into a stainless steel vessel equipped with a drain of bottom connected to a flow pump and a flow meter. A separate vessel also equipped the bottom with a drain, pump and a flowmeter is filled with an excess of P06 / 006AAI ammoniated methanol (1%). The two separate fluids are combined in a fixed ratio using the • flow meters using the static mixer and are deposited through the dispatch head on a flat surface of the moving conveyor. The silica sol material is pumped at a fixed rate through the dispensing head onto a flat surface of the moving conveyor (a width of 38"between the flexible edges.) A tension roller that comes into contact with the front surface of the Moving conveyor belt avoids backscattering of low viscosity sol.The speed of the conveyor belt and the deposit flow rate of sol material are synchronized so that the gelation front for the silica gel (monolithic) canvas occurs approximately At the midpoint along the length of the conveyor, the web speed is kept constant during the process to ensure that the ratio of syneresis time to gelation time is approximately 1: 1. Cured silica reaches a preferred length beyond the end of the conveyor belt (on a support surface to prevent cracking of the delicate a gel structure), a cutting apparatus is coupled to separate the individual piece from the gel continuously in motion. The new gel canvas moves on a P06 / 006AAI load support plate and it is withdrawn to another area for additional treatment. This action is repeated until all the sun material has been deposited on the table. Continuously you can run this process as long as you replace the sun material properly formulated in the deposit apparatus.

Example 5 Twenty gallons of silica sol produced by hydrolysis of a 20% TEOS solution in ethanol (at pH 2 at room temperature for 24 hours) are introduced into a stainless steel vessel equipped with a connected bottom drain. to a flow pump and a flowmeter. Ammoniated ethanol (1%) is added with stirring at a rate that maintains a nearly constant temperature until the pH of the sol material reaches a value between 4 and 7. The adjusted pH sol material ("catalyzed") is deposited in a container through a roll of polyester wadding (a width of 38 inches) with an approximate thickness of 0.5"that has been wound on a stainless steel mandrel with a polyethylene separating layer. the excessive formation of air bubbles within the volume of fibers, and in a way that can benefit from the use of techniques of molding by transfer resins or P06 / 006AAI vacuum infiltration techniques known to those skilled in the art. After the gelation has occurred, the gel roll is unwound before excessive hardening occurs (a gelation time rate at time of syneresis greater than 1: 1 is preferred), wherein the impermeable plastic layer is removed and the flexible gel is rewound with a permeable flow layer with an appropriate tension in a separate cartridge (Figure 6). The gelled roll is then readied for further curing and additional chemical processing before supercritical drying. In the descriptive embodiments of the present invention, specific terminology was employed for reasons of clarity. For the purposes of the description, each specific term is intended to at least include all technical and functional equivalents that operate similarly to achieve a similar purpose. In addition, in some examples where a particular embodiment of the present invention includes a plurality of system elements or method steps, these elements or steps may be replaced with a single element or step; similarly, a single element or step can be replaced with a plurality of elements or steps that serve the same purpose. Even more, although this invention has been shown and described with reference to P06 / 006AAI the particular modalities thereof, those skilled in the art will understand that various other changes in form and details may be made therein without departing from the spirit of the invention.

P06 / 006AAI

Claims (46)

1. CLAIMS; 1. A process for continuously molding solvent-impregnated gel cloth material, the process comprising: continuously combining a sol material and a gel-inducing agent to form a catalyzed sol material; and forming a gel sheet by dispensing the catalyzed sol material onto a moving element at a predetermined effective ratio to allow gelation to occur on the moving element. The process according to claim 1, wherein the sol material comprises a material selected from the group consisting of inorganic materials, organic materials and a combination of inorganic materials and organic materials. 3. The process according to claim 1, wherein the moving element includes edges. The process according to claim 2, wherein the inorganic materials are selected from the group consisting of zirconia, yttria, hafnium, alumina, titania, ceria and silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride, the combinations of these. 5. The process according to claim 2, wherein the organic materials are selected from the group consisting of polyacrylates, polyolefins, P06 / 006AAI polystyrenes, polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohols, phenol - furfuryl alcohol, formaldehydes of melanin, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, dialdehyde - polyvinyl alcohol, polyanurates, polyacrylamides, various epoxies, agar, agarose and combinations of previous The process according to claim 1, wherein it further comprises the step of: introducing mat material or fibrous batting onto the moving element for its combination with the catalyzed sol material before gelation. The process according to claim 6, wherein the moving element includes edges. The process according to claim 6, wherein the sol material comprises a material selected from the group consisting of inorganic materials, organic materials and a combination of inorganic materials and organic materials. . The process according to claim 6, wherein the inorganic materials are selected from the group consisting of zirconia, yttria, hafnium, alumina, titania, ceria and silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride of the combinations of these. P06 / 006AAI 10. The process according to claim 6, wherein the organic materials are selected from the group consisting of polyacrylates, polyolefins, polystyrenes, polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohol, phenol-furfuryl alcohol, formaldehydes of melanin, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, dialdehyde-polyvinyl alcohol, polyanurates, polyacrylamides, various epoxy, agar, agarose and combinations thereof. The process according to claim 6, wherein the fibrous batt material includes fibers selected from the group consisting of inorganic materials, organic materials and a combination of inorganic materials and organic materials. The process according to claim 6, wherein the fibrous batt material includes fibers having a diameter within a range of about 0.1 μm to 1,000 μm. The process according to claim 6, wherein the fibrous batt material includes fibers having a diameter within a range of about 0.001 μm to 10 μm. The process according to claim 1 or 6, wherein it further comprises the step of: distributing fibers P06 / 006AAI curled all over the gel canvas. 15. A process for continuous molding of gel cloth impregnated with solvents, the process comprising: continuously forming a gel canvas by dispensing the catalyzed sol material onto a moving element at a predetermined ratio; and inducing gelation in the moving element by a process selected from the group consisting of (a) a chemical process, and (b) dissipating a predetermined amount of energy from an energy source in a cross-sectional area of the sun material. 16. The process according to claim 15, further comprising the step of: introducing mat material or fibrous batting on the moving element for its combination with the sun material catalyzed before gelation. The process according to claim 15 or 16, wherein the energy source is selected from the group consisting of an infrared energy source, an X-ray energy source, a microwave energy source, a power source gamma ray, an acoustic energy source, an ultrasonic energy source, a particle probe energy source, an electron probe energy source, a beta particle energy source, an alpha particle energy source and P06 / 006AAI of the combinations of these. 18. The process according to claim 1, wherein the moving element is a conveyor belt. 19. A process for continuously molding solvent-impregnated gel cloth material, the process comprising: continuously combining a sol material and a gel-inducing agent to form a catalyzed sol material; and providing a first moving element and a second moving element, the second moving element moving in the same direction as the first moving element; forming a gel canvas having a first surface and a second surface when the catalyzed sol material is dispensed so that the first surface of the catalyzed sol material enters into communication with the first element and the second surface of the catalyzed sol material enters into communication with the second element in motion, wherein the first moving element and the second moving element move at a predetermined effective ratio to allow gelation to occur towards the sun material catalyzed on the first moving element and the second moving element. The process according to claim 19, wherein it further comprises the step of: introducing material from P06 / 006AAI mat or fibrous batting on the moving element for its combination with the sun material catalyzed before gelation. The process according to claim 19 or 20, wherein the sol material comprises a material selected from the group consisting of inorganic materials, organic materials and a combination of inorganic materials and organic materials. 22. The process according to claim 21, wherein the moving element includes edges for clamping the sun material. The process according to claim 21, wherein the inorganic materials are selected from the group consisting of zirconia, yttria, hafnium, alumina, titania, ceria and silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride, the combinations of these. The process according to claim 21, wherein the organic materials are selected from the group consisting of polyacrylates, polyolefins, polystyrenes, polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohol, phenol-furfuryl alcohol, formaldehydes of melanin, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, dialdehyde - polyvinyl alcohol, polyanurates, P06 / 006AA1 polyacrylamides, various epoxy, agar, agarose and combinations of the above. 25. A process for continuously molding gel cloth material impregnated with solvents, the process comprising: providing a first moving element and a second moving element, the second moving element moving in the same direction as the first element moving; dispatch the sun material on the first moving element; forming a canvas of sun material having a first surface and a second surface when the sun material is dispensed so that the first surface of the sun material enters into communication with the first element and the second surface of the sun material enters into communication with the second element moving; and inducing gelation by a process selected from the group consisting of (a) a chemical process, and (b) dissipating a predetermined amount of energy from an energy source in a cross-sectional area of the sol material. 26. The process according to claim 25, wherein further comprises the step of: introducing mat material or fibrous batt on the moving element for its combination with the sun material catalyzed before gelation. 27. A process for molding gel linens, the P06 / 00SAAI process comprises the steps of: providing a quantity of fibrous batting material; introducing a quantity of impermeable material to separate the amount of fibrous batt material in a fiber roll preform having a plurality of fibrous layers; infusing a quantity of catalyzed sol material into the fiber roll preform; gelling the catalyzed sol material in the fiber roll preform; remove the impermeable material to leave a remnant of a gel material; introducing a quantity of permeable material to separate the gel material into a plurality of layers. The process according to claim 27, wherein the catalyzed sol material comprises a material selected from the group consisting of inorganic materials, organic materials and a combination of inorganic materials and organic materials. 29. The process according to claim 28, wherein the inorganic materials are selected from the group consisting of zirconia, yttria, hafnium, alumina, titania, ceria and silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride, the combinations of these. 30. The process according to claim 28, wherein the organic materials are selected from the group consisting of polyacrylates, polyolefins, P06 / 006MI polystyrenes, polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohols, phenol - furfuryl alcohol, formaldehydes of melanin, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, dialdehyde - polyvinyl alcohol, polyanurates, polyacrylamides, various epoxies, agar, agarose and combinations of previous The process according to claim 27, wherein the fibrous batt material comprises a material selected from the group consisting of inorganic materials, organic materials and a combination of inorganic materials and organic materials. 32. The process according to claim 31, wherein the inorganic materials are selected from the group consisting of zirconia, yttria, hafnium, alumina, titania, ceria and silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride, the combinations of these. 33. The process according to claim 31, wherein the organic materials are selected from the group consisting of polyacrylates, polyolefins, polystyrenes, polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohol, phenol-furfuryl alcohol, formaldehydes of melanin, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, P06 / 006AAI dialdehyde - polyvinyl alcohol, polyanurates, polyacrylamides, various epoxy, agar, agarose and combinations of the above. 34. The process according to claim 27, wherein the fibrous batt material includes fibers having a diameter within a range of about 0.1 μm to 10,000 μm. 35. The process according to claim 27, wherein the fibrous batt material includes fibers having a diameter within a range of about 0.001 μm to 10 μm. 36. The process according to claim 27, wherein further comprises the step of: distributing crimped fibers throughout the gel sheet. 37. The process according to claim 27, wherein the gelation of the catalyzed sol material is intensified by a process selected from the group consisting of (a) a chemical process, and (b) dissipating a predetermined amount of energy from a source of energy in a cross-sectional area of the sun material. 38. The process according to claim 27, wherein the impermeable material is composed of a flexible canvas. 39. The process according to claim 27, wherein the gel material has a selected form of P06 / 006 I group formed by a mesh, a canvas, a perforated canvas, a sheet and a perforated sheet. 40. A process for manufacturing airgel blankets, the process comprising the steps of: providing a quantity of fibrous batting material; introducing a quantity of impermeable material to separate the amount of fibrous batt material in a fiber roll preform having a plurality of fibrous layers; infusing a quantity of catalyzed sol material into the fiber roll preform; gelling the catalyzed sol material in the fiber roll preform to form a roll of gel canvas; and dry the gel canvas roll. 41. A process for preparing gel canvases, the process comprises the steps of: dispatching a catalysed sun material on a moving element as a continuous canvas; winding the dispatched canvas in a plurality of layers. 42. The process according to claim 41, wherein further comprising the step of: providing a separating layer between any two predetermined layers of continuous canvas. 43. The process according to claim 42, wherein the separating layer is permeable. 44. The process according to claim 42, wherein the separating layer is impermeable. P06 / 006AAI 45. The process according to claim 43, wherein the permeable separating layer is effective to provide radial flow patterns in combination with a drying process. 46. The process according to claim 44, wherein the impermeable separating layer is effective to provide axial flow patterns in combination with a drying process. P06 / 006AAI