Method of making a product with a functional relief surface with high resolution

Abstract

A method of making products with a functional relief surface (2) with high resolution up to 10 nm, which is copied from a template (1) or carrier of the negative relief of the surface, the so-called master. The template (1) of the relief surface (2) is provided with at least one layer of geopolymer composite, applied in a precursor state (3), in form of a liquid dispersion or grout in plastic or thixotropic condition, whose thickness is the same or greater than the depth of the template relief (1), at temperatures in the interval from the temperature corresponding to properties of the precursor (3) to the temperature corresponding to thermal decomposition of the precursor (3), and after hardening of geopolymer composite the layer or layers is/are separated from the template (1).

Claims

1. A method of making a product with a functional relief surface with high resolution up to 10 nm, which is copied from a master comprising a template or carrier of a negative relief of the relief surface, wherein the template of the relief surface is provided with at least one layer of geopolymer composite, applied in a precursor state in the form of a liquid dispersion or grout in plastic or thixotropic condition, whose thickness is the same or greater than the depth of the template relief, at temperatures in a range from a temperature corresponding to the cryoscopic properties of the precursor to a temperature corresponding to thermal decomposition of the precursor, and after hardening of the geopolymer composite the layer or layers is/are separated from the template.

2. The method according to claim 1, wherein the application of layers of geopolymer composite in a precursor state is performed by casting, dip coating, spin coating and spraying or rolling of layers of a non-sagging grout, while minimizing formation of air bubbles.

3. The method according to claim 2, wherein the layer of geopolymer composite is during its formation exposed to vibrations, pressure or vacuum to achieve its proper contact with the template surface.

4. The method according to claim 1, wherein the formation of a layer or layers from geopolymer composite is performed at working temperatures from 5 to 50 C.

5. The method according to claim 4, wherein the formation of a layer or layers from geopolymer composite is performed at working temperatures from 20 to 25 C.

6. The method according to claim 1, wherein the dynamic viscosity of the initial dispersion for the formation of a layer or layers from geopolymer composite is in the interval from 1000 to 50000 mPas or is a non-sagging grout.

7. The method according to claim 1, wherein in order to increase the strength of the product while its fine structure on the surface is maintained, the product is structured in layers in a cross section perpendicular to the relief surface, by means of anisotropic fillers with grains of various shapes and sizes and by isotropic fillers and macromolecular substances, or by reinforcement with fibers and textiles made of mineral and glass melts, carbon, plastics and metal wires, while the functional part of the geopolymer composite layer, adjoining on the relief surface, has grains of smaller or the same size as the minimum dimension of the relief, while other layers of the product contain bigger particles of solid substances.

8. The method according to claim 1, wherein the binding geopolymer material in the geopolymer composite contains on average SiO.sub.2 from 20 to 95% wt., Al.sub.2O.sub.3 from 5 to 80% wt. and other substances recalculated to oxides, such as Fe.sub.2O.sub.3 from 0 to 79% wt., CaO from 0 to 79% wt., Na.sub.2O from 0 to 35% wt. and K.sub.2O from 0 to 35% wt., Li.sub.2O from 0 to 35% wt., TiO.sub.2 from 0 to 79% wt.

9. The method according to claim 8, wherein the binding geopolymer material in the geopolymer composite contains on average SiO.sub.2 from 46 to 80% wt., Al.sub.2O.sub.3 from 5 to 40% wt., Fe.sub.2O.sub.3 from 2 to 70% wt., CaO from 0 to 50% wt., Na.sub.2O from 0 to 35% wt. and K.sub.2O from 0 to 35% wt.

10. The method according to claim 1, wherein after the entire composite is removed or separated from the template the product is maintained at a constant humidity for a period from several hours to days.

11. The method according to claim 1, wherein the functional relief surface is a surface selected form a group including optically active surfaces, mechanical, hydromechanical, aerodynamic, adsorption or selective functional surfaces or data relief surfaces, while the functional optically active relief surface is selected from a group including optical diffractive relief surfaces, reflexive relief surfaces, refractive relief surfaces, electronic relief surface and data carrying surfaces.

12. The method according to claim 8, wherein the specific surfaces of the filler and other added solid substances are greater than 610.sup.2 m.sup.2/g, the geopolymer binder is the sole binder used, and the minimum content of the geopolymer binder is 10% wt.

13. The method according to claim 9, wherein the specific surfaces of the filler and other added solid substances are greater than 610.sup.2 m.sup.2/g, the geopolymer binder is the sole binder used, and the minimum content of the geopolymer binder is 10% wt.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The attached drawings show examples of execution of the invention hereunder. FIG. 1 schematically shows copying of a template of functional relief surface and formation of a master from geopolymer composite. FIG. 2 shows the principle of relief copying in presses for injection molding, extrusion and vacuum forming, or simple coating with plastic made of polymer suspension, by evaporating the solvent in which the polymer is dissolved or block polymerization on a master, where the geopolymer master with a functional relief is in place as a part of the mold. FIG. 3 shows a cylinder-shape geopolymer master with a functional relief on the surface. The relief is copied by pressure at the temperature of plastic softening into the surface of plastic foils by means of rotation against the press cylinder.

DESCRIPTION OF PREFERRED EMBODIMENTS

(2) Geopolymer composite (i.e. a material from the glass and ceramics group or materials, whose properties and look are similar to microporous ceramics) with a functional surface may serve as a final product shaped in space and plane. In other cases the geopolymer product provided with functional relief may be the template 1 and the master for further copying. A geopolymer master may be both planar (for copying in the plane) and cylindrical (for rotating copying) or otherwise spatially shaped. Copying can be performed with several methods:

(3) Planar Copying or Copying from Plane

(4) The first possibility to copy the relief from the geopolymer master is a copy into a dissolved, melted or polymerizing plastic or other material. A layer of moldable plastic is applied on a geopolymer master (separated and non-separated) and then left to solidify (by cooling, evaporation of solvent, change of solubility, polymerization etc.)see FIG. 2. After the solidification the resulting copy is separated from the geopolymer master. An example of coating with a layer from a plastic solution can be application of polycarbonate dissolved in methyl chloride. Another example of coating is formation of a layer on a geopolymer master by evaporation of polymer suspension, followed by application of polymerizing liquid methyl metacrylate which gradually hardens to form polymethyl metacrylate. Yet another possibility is copying by pressing in injection molding presses for plastics or vacuum forming where geopolymer master with a functional relief is a part of the mold.

(5) Rotagravure

(6) In this case the geopolymer master is a cylinder with a functional relief on the surface. The relief is copied at the temperature of the plastic softening into a surface of plastic foils (e.g. polyethylene terephtalatePET, polyvinyl chloridePVC, polypropylenePP, polycarbonatePC), or e.g. aluminum foils, by rotation against the press cylindersee FIG. 3.

(7) Manufacture of Other Templates and Masters for Copying of Surface Reliefs

(8) Reliefs Representing Information

(9) One example may be a geopolymer microdot made of geopolymer composite, provided with a relief carrying information. Another product with relief information may be e.g. a geopolymer plate with a copied relief which is used for data storage. The data may be read either with the naked eye or, if very small, with a magnifying glass, optical microscope or electron microscope. The data may be also legible with fingers (e.g. Braille) or with mechanical or laser sensors. The information may be a graphic reliefboth bitmap or vector, or entries consisting of a set of letters, figures or other alphanumeric characters; the relief may consist of signs or Braille characters etc. Geopolymer with a relief may be both the product and the template 1 for copying into other materials, plastics and metals, as well as geopolymer.

(10) Relief with Special Mechanical Properties

(11) A microrelief consisting of a very fine structure, whose individual elements alone in the macroscale are not functional, may have practically usable properties as a whole made up of a big number of such structures. One example is a relief which provides the surface with adhesive properties, although it is not covered with any glue. One such demonstration can be found in nature (the relief on gecko fingertips makes it possible for the animal to adhere even on a vertical surface). The basis of adhesion may be also microrelief with a function similar to a zipper. An opposite example may be a microrelief which generally reduced rolling and translation friction. The example is a microrelief with such a shape of relief structures that ensure sliding in only one selected direction. It may be used e.g. on running surfaces of skis etc. Another example are rough (anti-slip) geopolymer surfaces used on floor tiles, slant surfaces of structures, machines etc. Geopolymer with a relief can be both the product and the template 1 for copying into other materials, particularly plastics.

(12) Geopolymer with a Microrelief Increasing the Size of its Surface

(13) An example may be a product made of geopolymer composite with the surface enlarged with a microrelief and covered with catalytic material to operates e.g. as a catalyst for treatment of gaseous mixtures (e.g. in car exhaust fumesanother advantage here is the chemical and particularly thermal resistance of geopolymer materials). Another use of such catalysts may be in chemical industry, such as crude oil cracking, reaction columns etc., where the microrelief increases the size of the contact area for the reagents.

(14) Geopolymer with an Increased Surface Covered with Chemicals which is a Part of a Galvanic Cell

(15) The advantage in this case consists in the high specific surface in combination with chemical and thermal resistance.

(16) Geopolymer with a Surface Increased by a Relief

(17) The geopolymer surface is provided with a functional adsorption group. For adsorption or chemisorption the sorption capacity per unit of sorbent weight increases with the growing specific surface. Sorbents with rastered surface may be used in air filters, ion exchanger carriers e.g. for water softening, for sorption of radioactive and other substances, such as dust particles, in chemical industry, wastewater treatment etc.

(18) Geopolymers with Special Hydrodynamic and Aerodynamic Properties

(19) Microreliefs consisting of a very fine structure, whose individual elements alone in the macroscale are not functional, may have convenient and practically usable properties as a whole made up of a big number of such structures, in respect to the streamline motion of liquids and gases. They may be used for products whose microsurface relief enables better flow in one direction in comparison with other directions (e.g. reliefs that are in terms of shape and arrangement similar to fish scale or bird feathers). Such surfaces may be used on bodyworks of ships, aircrafts, trains, rockets or cars. Geopolymer with a relief may be both the product and the template 1 for copying into other materials, particularly plastics and metals. Geopolymer composite may form large-area masters in the shape of the individual parts of the jacket or the entire hull, fuselage or bodywork.

(20) Microrelief Surfaces with Topographically different Properties

(21) If a material bears a microrelief on its surface it may have different properties depending on its shape, e.g. in macroscale it may be hydrophobic or hydrophilic. The same situation occurs when a part of the surface is provided with a microrelief and another part is not. Such a surface may serve as e.g. printing cylinder that receives ink only on a part of its surface. Another example of topologically arranged microrelief elements are transport microchannels for micromanipulation with samples of liquids, tissue cells, for selective adsorption etc. The product in this case is a carrying substrate for scientific research, a functional layer for plastic cards provided with Lab on chip technology e.g. for detection of user's health condition etc. Geopolymer with a functional relief may be both the product and the template 1 for copying into other materials, particularly plastics and metals, as well as geopolymer.

(22) Microrelief Surfaces Electrically Conductive

(23) Electric conductivity associated with the relief structure may be used e.g. for adsorption or polarization of light, microwave or radio signals etc. An example of the use of such a surface may be the bodywork of military transport vehicles that prevent radar detection. A microrelief surface prevents reflection of radiation or disperses the radiation to significantly aggravate the detection.

(24) Geopolymer Composite may be also Used as a Printing Cylinder or Printing plate

(25) Examples of Products

(26) 1) An example of the product may be microdot, a product made of geopolymer composite with a microscopic relief on the surface with the smallest detail size 100 nm and the product size 20020050 m.

(27) Average composition: SiO.sub.2 45% wt., Al.sub.2O.sub.3 15% wt., Fe.sub.2O.sub.3 25% wt., Na.sub.2O 7% wt., K.sub.2O 8% wt.

(28) 2) Registration carda fireproof product made of geopolymer composite with an microscopic relief on the surface with the smallest detail size 100 nm and the product size 40300.8 mm.

(29) Composition of the binder matrix: SiO.sub.2 57% wt., Al.sub.2O.sub.3 23% wt., K.sub.2O 5% wt., Na.sub.2O 3% wt., Fe.sub.2O.sub.3 4% wt., MgO 2% wt., C 3% wt., armed with carbon fibers.

(30) 3) Master with a negative microrelief template, the product made of geopolymer composite resistant to cracking, with the smallest detail size 100 nm and the product size 40060025 mm.

(31) Composition of the binder matrix: SiO.sub.2 30% wt., Al.sub.2O.sub.3 14% wt., Na.sub.2O 22% wt., Fe.sub.2O.sub.3 20% wt., CaO 8% wt., P.sub.2O.sub.5 6% wt., filler of subsurface layers SiO.sub.2 60% wt., PMMA 10% wt.

(32) 4) Reaction column packinga product made of geopolymer composite in the shape of rings with an active relief surface, sized 153 mm, inside diameter d=5 mm.

(33) Average composition of the binder: SiO.sub.2 25% wt., Al.sub.2O.sub.3 10% wt., Na.sub.2O 5% wt., K.sub.2O 15% wt., TiO.sub.2 26% wt., ZnO 9% wt. B.sub.2O.sub.3 8% wt., Au.sub.2O.sub.3 1% wt., SO.sub.2 1 wt., filler of subsurface layers Al.sub.2O.sub.3 30% wt.

(34) 5) Substrate for sensors with active surfacesa product made of geopolymer composite in the shape of a plate 10101 mm.

INDUSTRIAL APPLICABILITY

(35) Geopolymer products with optically active relief surfaces with high resolution up to 10 nm may be e.g. in the form of security microelements protecting against forgery, e.g. microdots etc., provided with additional information on the surface. The geopolymer composite material may be complemented with additives, e.g. substances active in ultraviolet and infrared light; geopolymer may be also colored with a visible color. This enables a combination of the security feature of optically active admixtures with additional information on the surface.

(36) The range of products made of geopolymers with functional surfaces is potentially very broad.

(37) Generally, they may be divided into products and templates, i.e. molds for further copying (geopolymer masters). Examples of products are surface boards with reliefs and optical properties (the absorption of light and other electromagnetic radiation, light reflection, polarization, color effects etc.) or mechanical or hydromechanical properties (hydrophobization of the surface, streamline motion, selective adsorption of organic, inorganic and live organisms etc). The relief structure may significantly increase both the specific surface of the product and the size of product surface, reactivity of adsorbed or otherwise deposited substances, it may serve as a filtration element etc. In practice they may be used in parts of solar collectors, faade lining and functional interiors (e.g. disinfecting in connection with TiO2) and designed surface finish of products. Further, they may be used in linings that improve streamline motion around the product (air, water), for improvement of surface properties of reservoirs, piping, turbines, ship hulls, car bodywork, aircraft fuselage, parts of sorption equipment, filters (chemical and mechanical), sanitary technology, chemical reactors, refrigerating equipment (by increasing the surface area), carriers for catalysts and chemical agents, chemical batteries, hydrogen sorbents in fuel elements. They may also serve as anti-slip and abrasive materials or parts of machines or, in the case of geopolymer composites with conductive fillers, also as parts of radars or anti-radar surfaces etc.

(38) Geopolymer masters may be used for planographic printing or for or rotogravure. It is also possible to consider geopolymer cylinders or printing plates for high resolution printing. Classical printing methods focus on the smallest printing point sizes at the limit (or below the limit) of discrimination with naked eye. In general, the best quality printing techniques are capable of printing a point from ca. 30 micrometers. For the classical polygraphy market those technologies are sufficient. One obvious application for higher resolution can be in printing of valuables (protection of governmental interests and protection of owners of established brands), not only in quality printing for inspection purposes but also for a combination of printing with optical filters (moir, polarization filters etc.), as well as for a combination with optics on a foil (refractive, e.g. lenticular films with high resolution or diffractive, e.g. for 3D personalization of ID cards, driving licenses, passport pages, etc.) The last mentioned combination can be interesting for development of new visual effects. Another big field of application is in printed electronics. For quality printed diodes, transistors and circuits the common requirement is the sub-10 micron resolution. Planographic printing is more convenient for laboratory tests while rotogravure is suitable for mass production.