EP2132048A2

EP2132048A2 - Iridescent assembly

Info

Publication number: EP2132048A2
Application number: EP08751513A
Authority: EP
Inventors: Fulvio Jacocagni
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-03-19
Filing date: 2008-03-17
Publication date: 2009-12-16
Also published as: WO2008114302A3; WO2008114302A2; ITMI20070538A1

Abstract

An iridescent/dichroic assembly (5) is proposed, comprising a support body or substrate (20; 40) and an iridescent external finish (50), on at least one part of the surface of said support body or substrate (20; 40), formed by a plurality (50) of dichroic layers of metallic oxides applied with the ionic vaporisation technique, which support body or substrate (20; 40) of the dichroic multi-layer (5) is constituted by a non-transparent material, e.g. for the production of tiles (10), or by metal for the production, for example, of watch cases, watch straps, cutlery, jewellery and bijouterie items, and the like, or by synthetic materials, with or without metal core, for the production, for example, of eyeglass frames, or of fabrics, and the like. In the apparatus for ionic vaporisation under vacuum, a rotary support plate for the bodies or substrates to be treated is provided.

Description

"Iridescent Assembly'

Description of the invention

Technical Field

The present invention relates to an iridescent assembly according to the preamble of claim 1.

Background of the invention

The term iridescent or colour-changing assemblies means bodies provided with a thin external layer or coating, whose chromatic appearance is variable according to the angle of incidence of the light and to the angle of observation.

Iridescent assemblies are known in different embodiments and obtainable with different methods. The document US 5,032,429 describes a method of producing luminous, wear-resistant decoration on a body of porcelain, ceramics, earthenware, sandstone, enamel and the like.

The method comprises several steps, i.e. coating the ceramic or similar base with a precious metal coating, coating the said precious metal coated base with a decorative colour preparation comprising a glass flux and mica platelets, which are coated with a thin light-impermeable coating or a thin light permeable coating or a metallic oxide, and steps of stoving the base having the precious metal coating and the decorative colour coating at a temperature in the range of about 500 to 1,100° C. Said patent then specifies, column 5, lines 4 - 10, that the so-called noble metal preparations contain noble metal in the form of organic compounds, such as the resinate or sulforesinate, which are known in the art and are provided as solutions in organic solvents such as aromatic and terpene hydrocarbons and polymeric binders can also be present. In example 1 the glass flux comprises 50% by weight of PbO and stoving takes place at 800⁰C for 50 minutes.

The method disclosed in said US 5,032,429 therefore requires heat treatments with high energy consumption, the use of solvents, the _ p _

execution of a plurality of different steps and the use of toxic lead compounds. Therefore, it is costly and environmentally unfriendly.

The document US 5,304,516 discloses transparent or opaque glassy coatings fired onto a ceramic body, which coatings can be of the "raw" type or of the "fritted" type, where raw coatings are used at high firing temperatures (> 1,15O⁰C) on substrates such as porcelain (1,300⁰C) whereas in "fritted" coatings all or part of the ingredients have been prefused and quenched to form one or more frits. The frits are ground and mixed with other constitutes (natural materials such as china clay) to formulate the final glaze composition.

Glaze compositions are proposed which are free of lead and cadmium and are formed by a high quantity of components and can be applied to a wide range of ceramic substrates, including opal glass, vitreous products and earthenware. Numerous compositions providing the use of numerous components are provided, where any method can be used that is suitable for applying the coating on the substrate body, such as ceramic. The firing temperature of the coated ceramic substrate is between 950° and 1,250⁰C. This document also provides costly steps of firing at high temperature.

The document US 5,618,585 discloses a method for producing a coated system which has a surface coating that is very stable chemically and mechanically and high aesthetic attraction and that has an iridescent colour and/or a body colour on a metal, ceramic or quartz glass substrate provided with an enamel or glaze coating. The method comprises single or repeated application aqueous colloidal solutions of metal oxides, with a particle dimension between 5 and 200 nm, with subsequent drying and optionally igniting at temperatures higher than 700⁰C and below the softening point of the substrate, where the total thickness of the ignited metal oxide coatings is between 20 and less than 500 nm.

No relationship is indicated between the thickness of the coatings and wavelengths. The teachings of this patent, too, provide steps of heating at high temperature requiring high energy consumption.

All iridescent assemblies according to the patents discussed above share the fact that in the determination of the composition and thickness of the layers to be applied onto bodies or substrates the wavelengths of the individual colours are never taken into account and it is not possible to establish beforehand, by calculation, or in another manner, except empirically, the iridescent or varicoloured effect desired in each case.

Iridescent/dichroic assemblies are known, such as interferential filters, dichroic mirrors and theiike, which superficially present a chromatic or iridescent aspect that is variable according to the angle of incidence of the light and of the angle of observation. These dichroic complexes are constituted, in principle, by a "transparent" support body or substrate whereon they are applied in superposition by means of coating by thermal vaporisation and condensation of thin layers of metallic oxides presenting a low and high refraction index, such as respectively of quartz and titanium oxide, wherein moreover the thickness of the layers is λ/4, i.e. ¹A of the wavelength selected in each case. Moreover, with regard to the layer, it is necessary to diversify absorbing and non absorbing layers (according to the materials of the layers) and homogeneous and non homogeneous layers (according to the construction of the packet of layers), wherein in homogeneous layers the optical constants are generally equal at all points, whereas in non-homogeneous layers the constants vary therein.

In practice, when light hits such a layer or such a system of layers, in general a part of the light is reflected, another part is scattered, an additional part is absorbed and the remaining part traverses the dichroic complex; however, in the dichroic layers scattering is so small as to be negligible in practice.

Said dichroic complexes are substantially used in the optics field, in which the absorption of the layers is very small and can be ignored, where said complexes or dichroic filters have very small dimensions, e.g. in the range between 0.5 and 50 mm.

The fabrication of such small dichroic complexes requires the use of small sophisticated equipment operating under condition of extreme cleanliness, under high vacuum, which, together with the limited number of pieces required by said optical field, leads to a limited exploitation of said equipment and to a high cost of said dichroic complexes or filters. - A -

Summary of the invention

The object of the present invention is to indicate how to use the known art and technologies for coating known transparent bodies or substrates for iridescent/dichroic assemblies of the optical sector, by ionic vaporisation of thin layers of metallic oxides, to obtain new iridescent/dichroic assemblies, exploiting in a different and dedicated manner the physical phenomenon of the reflection/transmission of light in bodies.

This object is achieved, according to the invention, with iridescent assemblies having the features of claim 1.

Whilst with known complexes or dichroic filters on transparent body or substrate the dichroic layers are obtained in such a way as to let one colour pass through and reflect the others, with the iridescent/dichroic assemblies according to the invention on non-transparent bodies or substrates, e.g. with white surface, and for the blue colour/effect, not only, though mainly, yellow and red are reflected, but also cyan, which normally would traverse it in the transparent support, wherein this creates varicoloured or colour- changing effects ranging from dark blue to cyan with golden yellow hues, depending on the angle of incidence of the light and on the angle of observation. What applies for the white surface and for the blue colour/effect obviously also holds true in principle for the other non-transparent surfaces and other colours.

With the iridescent assemblies according to the invention, numerous and important advantages are achieved.

Advantages

In the first place, with the teaching of the invention the art and technology of thin layers of oxides applied by ionic vaporisation, known and used for over 40 years substantially in the optical field alone, i.e. on "transparent" bodies or substrates, can now be used on "non-transparent" bodies or substrates in general, so said iridescent/dichroic coating of multiple thin layers of oxides can now be applied on bodies or substrates substantially at will, e.g. on tiles for floors or coatings, glass frames, watch cases and straps, necklaces, bracelets, jewels and jewellery and bijouterie objects in general, fabrics and so on, which heretofore had been precluded from having permanent and resistant iridescent finishes.

To said iridescent assemblies with non-transparent body are therefore opened not only new and original embodiments, but also with the chromatic iridescence effects desired in each case, since said chromatic effects can be calculated beforehand.

Another advantage of the invention is that only two materials are used, which are layered with a number of layers and with layer thickness values that are established a prior, to obtain different colours.

According to the invention, it is also advantageously possible to provide the iridescent assemblies with a thin layer of very hard transparent outer coating, e.g. with the hardness of quartz, zirconium, sapphire, and so on.

Non-transparent supporting bodies or substrates can have the colour white, black, or any other colour at will.

The tiles treated according to the invention are usable both for indoor and outdoor construction work, as well as in particular constructions, e.g. for swimming pools.

In the case of tiles for coating swimming pools with iridescent or colour- changing effects in the hues of blue, green, sand-colour and the light, "near-real" alternating effects of shallow and gradually deeper marine bottoms can be obtained, for example.

In any case with the new iridescent/colour-changing tiles, design freedom for architects and interior decorators is considerably expanded, to obtain heretofore unobtainable aesthetic solutions.

Note that the hard external protection layer added to, or incorporated in the proposed multi-layer, provides high resistance against weather elements, humidity, temperature fluctuations and abrasions caused by mechanical factors and/or by aggressive substances, such as detergents or other solvents used for household cleaning, which is very important in particular in the case of tiles for floors and wall coverings of kitchens, bathrooms and living spaces in general.

An additional advantage is that in the treatment method according to the invention no toxic solvents or oxides are used, so the iridescent assemblies thus produced are environment-friendly, and there are no costly heat treatment steps, which, aside from being expensive in terms of energy consumption, would also prolong production times.

The step of pre-cleaning the body or substrate, performed for example by bombardment with ionised gas, assures an extremely resistant and durable physical-chemical anchoring of the dichroic multi-layer on said body or substrate.

An additional advantage is also that the proposed dichroic multi-layer or coating maintains both its optical and qualitative characteristics even after long exposures to high temperatures, i.e. up to over 450⁰C.

Relative to the method and to the system for plating the dichroic multilayer on the bodies to be coated, it is advantageously possible to use to a large extent the traditional technique and equipment, which can easily be adapted to the different requirements for the production of the different bodies, e.g. tiles, fabrics, eyeglass frames and so on.

As mentioned above, it is stressed that the desired iridescent/colour- changing effect of the iridescent assembly can at first be determined through calculations and then the calculated data are inserted, by programming, into the operating system controlling the ionic vaporisation equipment.

Further characteristics, details and advantages of the teaching of the invention shall become more readily apparent from the following description of an iridescent assembly according to the invention, formed, by way of example, by a tile, with reference to the accompanying schematic drawing, in which: figure 1 shows a section through a traditional tile for coating walls or floors,

figure 2 shows a similar section through a tile with a dichroic multi-layer according to the invention, and

figure 3 shows a section view of a swimming pool with its bottom coated with tiles according to the invention.

Detailed description of the preferred embodiments

Figures 1 to 3 are shown in a convenient scale, the better to highlight the teaching of the invention.

Reference is at first made to figure 1, which shows an exemplifying tile 1 of the prior art, having a body 2, e.g. made of clay, sandstone, or similar material, which can have, in the top view, any geometric shape, e.g. square, rectangular or otherwise polygonal, with a bottom side 3, to be fastened onto a wall, floor or the like (not shown) by means of a layer of mortar, glue or the like. The reference number 4 designates a coating/finishing layer at will, e.g. made of porcelain, to be executed at will according to the most disparate known techniques and fabrication material.

From figure 2 it can be noted that the tile 10, treated according to the invention, has, similarly to the prior art, a body 20 with a bottom side 30 and a coating of porcelain, or the like, 40, and on said coating 40, serving as non-transparent body or substrate to be coated according to the invention, is applied, by means of the known technique of ionic vaporisation, a dichroic multi-layer 50 pre-calculated in each case in the number of the individual layers and of the metal oxides to be vaporised according to the invention according to the desired colour, where the reference number 5 designates the iridescent/dichroic assembly according to the invention formed, in the illustrated example, by the multi-layer 50 and by the related support body or substrate 40, or 20, as shown hereafter.

Said multi-layer, in a simple indicative example, is formed by a first thin dichroic layer 51 and by a second thin dichroic layer 52, obtained for example with known metal oxides, simple or combined, applied by ionic vaporisation and having different refraction indices and different thickness (about ¹A of the wavelength, e.g. 162.5nm for the colour red) calculated and optimised by iterations in such a way that, plated onto a polished white non transparent support, the observer perceives viewing a colour-changing or iridescent effect from dark blue to light sky blue (cyan), according to the angle of incidence of the light and to the angle of observation.

With a higher number of dedicated dichroic layers, said varicoloured effect can also manifest itself in zones in different manners on the same surface, e.g. on the bottom 60 of a swimming pool 61 coated with tiles 10 according to the invention, where in the illustrated example the light tends to strike the tiles 10 from different angles, and more specifically according to the arrows F of the ambient light and the arrows Fl, F2, F3 and F4 of the light originating from spotlights 62, illustrated by way of example.

These combinations of thin layers made with ceramic materials are in themselves very resistant to external agents and to abrasion.

In addition to this characteristics, over the dichroic multi-layer 50, or to the outermost dichroic layer 52 of the series of layers provided in each case, may advantageously be applied or incorporated, also by ionic vaporisation, an additional hard protection layer 53, e.g. quartz, zirconium, sapphire and so on.

In practice the dichroic multi-layer 50 may have any number of superposed dichroic and hybrid layers, which may have different thin thickness, as recalled above, that will be pre-calculated in each specific case according to the desired varicoloured effect/colour on the substrate or tile having a known colour, which is taken into account in pre-calculating the dichroic multi-layer to be applied.

In practice to assure an optimal fastening of the first thin layer of oxide onto the surface to be treated of the tile, or the like, said tile or the like, as supplied by the manufacturer, is subjected to a step of thorough cleaning, e.g. by means of a bombardment with ionised gas, known in itself, which takes place in the same apparatus or process chamber under vacuum, which step is integrated in the process itself. A pilot plant, dimensioned for the treatment of about 20 square metres/hour on an industrial scale, is provided with a support of the tiles in the form of a rotary drum associated with the devices positioned laterally, such as cathodic magnetron and ionic source, in the apparatus or chamber for the treatment , i.e. ionic vaporisation under vacuum.

After the application of the dichroic multi-layer 50, the outer protection layer 53 is applied, which is transparent to preserve the iridescent aspect of the multi-layer 50 on the non-transparent body or substrate 20, respectively 40.

Examples

Example 1 : yellow tile with iridescent/colour-changing effect.

To obtain a yellow colour, with a determined lemon yellow hue, two metal oxides are used, e.g. SiO₂ and TiO₂.

The number and the thickness of the layers are established by calculation as follows:

starting from the alternated system of the two aforesaid elements (HL)^X (where H is titanium oxide and L is silica oxide) whereof H and L will have a thickness of one fourth the wavelength to be reflected, the mathematical optimisation is then performed through iteration of the design, to obtain an optimal transmission/reflection in the sector of visible light, the thickness data of the individual materials in the calculation sequence are inserted in the memory of the production plant which, by means of its own algorithm, controls the various components such as the high vacuum pumping systems, the valves for the inflow of the process gases, the magnetrons, the ionic guns, the layer growth control optical system, the internal temperatures, substantially the entire step of the process, including the output of the finished product from the process chamber.

Example 2: sandstone tiles with colour-changing blue/cyan effect. In this case the dichroic multi-layer will comprise no less than fifteen layers with thickness values of about one fourth the wavelength of the desired colour (164.25nm).

In this case, too, two metal oxides, or combinations of different metal oxides, will be used, also according, for example, to the desired hardness of the multi-layer.

From the above illustration it is readily apparent that the preliminary calculation of the multi-layer to be applied on the tile, or other non- transparent support, or of the related number of dichroic layers is fundamental to obtain the desired result.

In practice, it is also necessary to take into account the base colour of the tile (polished white provides the optimal situation to obtain the aforesaid effects), of the optical components (transmission: e.g., blue; reflection: e.g. yellow) and take into account that the part transmitted by the dichroic system is in turn partly reflected by the surface of the support in different fashion depending on the angle of incidence of the light.

The above description in relation to the example of the tiles applies in principle also for any other non-transparent body or substrate of the iridescent/dichroic assemblies according to the invention.

From the above description, it is readily apparent that with the teaching of the invention the indicated object is effectively achieved and the mentioned advantages are obtained.

Although in practice metal oxides provide the best characteristics of hardness, resistance to chemical aggressions and atmospheric agents and stability in time, the scope of the invention also includes vaporising on the bodies or substrates of the iridescent assemblies also metals, in their most disparate forms, as well as other suitable substances, such as inorganic or organic substances.

In practice, those skilled in the art may propose modifications and variants concerning, for example, the application of the teaching of the invention on substrates or artefacts of any materials and colours at will, e.g. on cutlery, and so on, without thereby departing from the scope of the present invention, as defined in the appended claims.

Claims

1. An iridescent assembly comprising a support body and an iridescent external finish, on at least one part of the surface of said body, formed by a plurality of dichroic layers applied with the technique of thin layer ionic vaporisation, characterised in that the support body of the iridescent assembly (5) is constituted by a non-transparent material.

2. Iridescent assembly as claimed in claim 1, characterised in that the support body or substrate is formed by a floor or wall tile (10), by a crockery item or the like.

3. Iridescent assembly as claimed in claim 1, characterised in that the support body or substrate is formed by a watch case or strap, by a jewellery and/or bijouterie item by an eyeglass frame or part thereof, and so on, with a non-transparent body constituted by a metal, by a natural material or by a synthetic material with or without metal core.

4. Iridescent assembly as claimed in claim 1, characterised in that the support body or substrate is formed by a fabric.

5. Iridescent assembly as claimed in one or more of the claims 1 to 4, characterised in that on the dichroic/iridescent multi-layer provided to obtain the chromatic degree or variation of iridescence is applied, or incorporated, a last thin transparent layer of high hardness, constituted for example by diamond, sapphire, quartz, zirconium and so on.

6. Iridescent assembly as claimed in one or more of the claims 1 to 5, characterised in that it has a number of thin layers of oxides, a type of metal oxides, and any number of possible hybrid layers, provided and pre-calculated to obtain the iridescent/colour-changing effect desired in each case. - 2 -

7. Iridescent assembly as claimed in one or more of the claims 1 to 6, characterised in that the support bodies or substrates have white, black or another colour.

8. Use of the method for applying thin layers of metal oxides by ionic vaporisation under vacuum on non-transparent bodies or substrates.

9. Use of an apparatus for applying thin layers of metal oxides by ionic vaporisation under vacuum on non-transparent bodies or substrates.

10. Use of an apparatus for applying thin layers of metal oxides by ionic vaporisation under vacuum on non-transparent bodies or substrates, characterised in that, for an industrial production, of e.g. 20 square metres/hour, of tiles according to claims 1 and 2, said apparatus has a rotary support for the tiles, or other support bodies or substrates to be treated, underneath the cathodic magnetron and the ionic source.