JP2005220011A - Sheet-like glass-ceramic body having at least one matted portion, and method for manufacturing glass-ceramic body of the same kind - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet-like glass-ceramic body, having at least one matted portion which is formed on the glass-ceramic body without using an expensive or dangerous substance, and which can withstand thermal and mechanical loads even when the glass-ceramic body is used, for example, as a cooking plate. <P>SOLUTION: The matted portion is formed by forming on a ceramic material a coating of glass having softening points higher than 750°C, which is melted into a matting form on a glass-ceramic material, and having a different refractive index from that of the glass-ceramic material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a sheet-like glass-ceramic body having at least one matte portion, in particular a glass-ceramic plate used as a cooking plate. However, it is also possible to use the sheet-like glass-ceramic body according to the invention for the production of viewing windows and lamp covers, for example viewing windows of fireplaces or ovens.
The invention further relates to a method for producing a glass ceramic body of the above type.

Modern cooking hobbs are generally equipped with a glass ceramic cooking plate with individual cooking portions or cooking positions that are heated by a gas, induction or electrically operated radiator.
Known glass-ceramic cooking plates are generally darkened or blackened to ensure that the interior of the hob is not visible. Such coloring can be carried out by coloring the molten glass ceramic starting material or by applying an optically opaque colored coating on the underside of the corresponding glass ceramic plate.

  Glass ceramic plates that are inherently continuous and homogeneous in appearance are typically given a certain marking that also serves as a decoration, such as marking the cooking zone of a continuous cooking hub, in order to enhance their suitability. Is done. This type of marking can be made by various methods. One method which forms the basis of the present invention is to form a matte portion that is clearly different from the surrounding cooking plate. The reason for matting in this way is that the surrounding cooking plate is very smooth and glossy.

  Glass or glass-ceramics are usually sandblasted on the surface or etched into the surface using hydrofluoric acid according to the prior art (Rompp Chemie Lexikon, August 2003, “Glossy Glass”) Can be matted. In the case of sandblasting, as described in, for example, German Patent DE 3212133 A1, by selection of abrasive particles as described in Japanese Patent Abstract No. 2001062727A and European Patent 1236696A, or during etching treatment using hydrofluoric acid. The appearance of the surface can be changed by selecting a proper composition, or by selecting the duration of action of the etching ink, such as a mixed solution of barium sulfate, ammonium sulfate, and hydrofluoric acid.

  However, hydrofluoric acid vapor is highly toxic and should not be used during production as much as possible, so it is not a particularly suitable method for matting glass ceramic cooking. Furthermore, when only a certain portion of the cooking plate is to be matted, a complicated masking treatment is required for the etching and sandblasting processes.

  In European Patent EP 0 464 323 B1, a matting method for a glass ceramic cooking plate is presented in which the cooking zone is matted using a matting ring to distinguish it from the rest of the cooking plate. In this method, the matte portion is formed by removing the material using a laser that is extremely expensive when matting a considerably large area.

As another possible method of forming a matte part on a heat resistant material, Japanese Patent Abstract No. There is a method of curing a resin by adding a filler such as ZnO or SiO ₂ to the resin in a thermosetting resin treatment as described in 57107271A. However, this type of resin can only withstand temperatures up to 400 ° C, so the coating is suitable for coating glass ceramic cooking plate parts that remain low temperature (below 400 ° C) during operation. Only suitable.

  Other glass ceramic bodies, particularly the sheet-like glass ceramic bodies mentioned at the beginning, have similar problems.

  The present invention provides a matte part capable of forming a matte part capable of withstanding high heat and mechanical load on a sheet-like glass ceramic body in a technically simple and safe manner during use of the sheet-like glass ceramic body. It was made for the purpose of manufacturing.

  In the case of a sheet-like glass-ceramic body provided with at least one matte part according to the invention, the object is a glass that is melted into a matte shape on a glass-ceramic material and has a softening point higher than 750 ° C. And by forming a matte portion by coating the glass ceramic material with a glass having a refractive index different from that of the glass ceramic material.

With respect to the method for forming the matte portion, the object of the present invention is achieved by providing a method for producing the sheet-like glass ceramic body from a raw glass body comprising the following steps. This manufacturing method is
Preparing an adhesive glass powder comprising a glass melted in a matte shape on a glass ceramic material and having a softening point higher than 750 ° C. and having a refractive index different from that of the glass ceramic material; ,
Applying the adhesive glass powder to the matte portion of at least one side of the glass ceramic body that has been ceramicized from the raw glass body or the raw glass body;
It is comprised from the process of baking the prepared said adhesive glass powder in the heating process different from the processing process to the ceramicized glass-ceramic body during the ceramic processing of the said raw glass.

  The separate heating step can be configured, for example, as a baking operation, that is, an operation of melting and melting the glass powder at a temperature of 850 ° C. to 900 ° C. for 20 minutes.

  The method according to the invention can withstand high heat and mechanical loads due to the glass properties of the coating, especially when used as a cooking plate, with a technically simple and safe manufacturing process, and with a refractive index of It is possible to obtain a sheet-like glass-ceramic body in which a matte portion that can be visually clearly distinguished from the difference is formed.

  It is also possible to matte the entire surface of the sheet-like glass ceramic body. In this case, the overall appearance of the glass ceramic body appears to be changed by matting. Also, fingerprints and small damage (scratches, etc.) will not be noticeable.

It has been experimentally confirmed that borosilicate glass having a relatively high softening point (E _w ) (for example, glass such as Borofloat (registered trademark), Saprax (registered trademark), Duran (registered trademark)) is particularly suitable. (E _w = 750-850 ° C.). Such suitability is related to the feature that the softening point is a temperature at which the viscosity of the glass is 10 ^7.6 dPa · s.

  Furthermore, the borosilicate glass must have a different refractive index than the glass ceramic. The refractive index should preferably differ by 0.03 or more.

In selecting a glass, thermal expansibility is also an important factor. The thermal expansibility must be less than ^{7.10 -6} K ^-1 to ensure that the coating adheres to the glass ceramic. For example, very low thermal expansion glass such as Borofloat (registered trademark) 3.3 having a thermal expansion coefficient of only 3.3 · 10 ⁻⁶ K ⁻¹ described in German Patent 19643870C2 This is advantageous because the decrease in the strength of the coated glass ceramic is very small compared to when high glass is used. When a frosted glass ceramic is used as a cooking plate, it is advantageous for installation or transportation of the cooking plate, for example, if the upper surface of the cooking plate is as high as possible in terms of tensile strength.

Coating with glass can be accomplished by screen printing if the glass is present in a paste form as the final ground shape (d ₉₉ <10μ) in a standard screen printing medium. Known glass melting compositions commonly used as decorative colors, for example described in German patents DE 197 21 737 C1, DE 198 34 801 C 2 and DE 420 1286 C2, have a softening point of these glasses that is too low (Ew <750 ° C.) and a refractive index of standard glass ceramic The glass has a similar refractive index, i.e., these glasses are not suitable because they melt as a transparent glossy coating.

  Matting can be carried out by the above method not only for black glass ceramics but also for colored (for example, blue, white, cream) glass ceramics or colorless glass ceramics.

If the borosilicate glass used is Borofloat (registered trademark) 3.3 (d ₉₉ <4.5 μ), which is very finely pulverized, a particularly homogeneous, overall matt appearance can be obtained. The borosilicate glass thus pulverized into fine particles and substantially free of agglomerates can be obtained by adding isopropanol and pulverizing in water, or by pulverizing in pure isopropanol (in an explosion-proof device). it can.

Example A substrate which has the shape of a glass plate made of a black-colored glass ceramic as described in German patent DE 197 21 737 C1 and which is known under the name Seran High Trans® and which is described in European patent EP 020333 B1 In the non-ceramic state, ie its corresponding raw glass substrate is based on a mixture of aromatic hydrocarbons (eg produced by Zschimmer & Schwartz GmbH & KG Chemische Farken) and Boroflot® 3.3 which is a borosilicate glass. Coating was performed by screen printing using a paste consisting of the screen printing medium as the material. The preparation ratio of the paste was 10 parts by weight of glass powder with respect to 12 parts by weight of the screen printing medium. The mesh width of the screen was 36 μm.

The data regarding the glass powder is as follows.
Composition of Borofloat (R) 3.3 (according to German patent DE19643870C2)
Oxide weight% (± 0.3)
SiO ₂ 80.9
B ₂ O ₃ 12.8
Na ₂ O 3.3
K ₂ O 0.6
Al ₂ O ₃ 2.4
Purifier: NaCl

Glass powder particle size distribution particle size Slip (dispersion) Powder D10 [μm] 0.4 0.4
D50 [μm] 0.9 0.9
D99 [μm] 2.6 4.1
(Analysis method: CILAS 1064L)

Glass refractive index glass n _D
Seran High Trans (registered trademark) 1.549
Borofloat (registered trademark) 3.3 1.473
(Measurement method: V-block method)

The coating was fired during ceramization in a continuous production furnace at a temperature up to about 900 ° C. (according to German patent DE 197 21 737 C1). The layer thickness after ceramization was 2.5 to 3.5 μm, and since the glass ceramic was black, the coating had a matte black appearance as a whole. Color measurement using a CIELAB instrument showed that the coating was deeply black despite the fact that it did not contain any pigments (L ^* values are quite significant for coated glass ceramics). Low). The color values for the uncoated glass ceramic are L ^* = 24.8, a ^* = − 0.1, b ^* = − 0.6. The color values for the glass ceramic with a matte black coating are L ^* = 22.3, a ^* = 0.1, b ^* = − 0.8. Reflection, ie light reflected at an angle of 90 °, was also measured by visible light normal emission with a wavelength of 400-800 nm. The reflection with a glass ceramic without coating was 10-11%. In contrast, the reflection from the matte coated part was only 6-8%.

  The use properties of the coating are very good.

  The measurement of adhesive strength was performed using a transparent adhesive film (Tesa Film (registered trademark), model 104). A small piece of the film was pressed firmly against the coating and then peeled off rapidly. There was no adhesion of the coating particles to the pieces, indicating that the coating layer had very good adhesion strength.

  The coating was tested for acid resistance by treating 4% acetic acid at the boiling point for 4 hours. Even after this test, no visible change was observed in the coating.

  The bending strength of the glass ceramic coated on the entire surface was 70 to 75 MPa (measured value according to German Industrial Standard EN1288-5). The bending strength of the glass ceramic decorated with a standard spot pattern was in the range of 88-105 MPa, depending on the coating coverage. The covering degree was 4% or 19%, and the edge length of one decoration spot was 0.48 mm.

The strength of the glass-ceramic cooking plate decorated with glass flux (no pigment) known from European patent EP1119524B1 is also the above-mentioned pattern (100% coverage full surface coating, 4% coverage light spot pattern, 19% coverage density). Spot pattern). The bending strength measured according to German industry standard EN1288-5 was 88-100 MPa for the spot pattern and 70-75 MPa for the total coating on the entire surface (100% coverage).
Accordingly, the strength of the matte-coated glass ceramic is much higher than the level conventionally used (average overall coating value according to German industry standards: 33 to 35 MPa) and the decoration described in the claims of European patent EP1119524B1 The color was comparable.

  In addition, the cleaning properties of the coated surface are burned until carbonized with a mixture of various food products (boiled juice, custard powder, flour, milk, egg, oil) and then commercially available cleaning agents (eg Sydol®, manufactured by Henkel) ) Was used for the test after removing the carbide. In this test, there was no visible residue of burned foodstuff on the decorative glass ceramic. This indicated that the coating had excellent cleaning properties.

  Said coating is for example by a mixture of gravy, egg, milk, sugar, flour, cheese, sago and tomato puree burned for 10 minutes between a glass ceramic plate and a cooking pot as described in French patent FR 2732960 It can withstand extreme levels of fouling as compared to conventional glass ceramic decoration methods. In the case of the conventional decoration scheme, clear traces that cannot be removed again remain after only one or two test iterations, whereas the matte coating has an equivalent appearance after three iterations.

  Acid and alkali resistance and abrasion resistance are measured using standard known methods, so that matte according to the present invention meets the requirements for decorative layers of glass ceramic cooking plates It has been shown. In addition, it has been shown that matt glass ceramics are much less susceptible to fingerprint fouling at the matt coating.

  In addition, the roughness of the matte part according to the present invention was measured and compared with the known decorative color roughness. The results are shown in Table 1 below in relation to FIGS. 1 to 5 represented by topographic maps.

  For the measurement of the roughness, an optical method in accordance with German Industrial Standard EN ISO 4288 (FRT Micro Glider (registered trademark) equipment) was used to measure each of the five standards with a scanning interval of 5.6 mm. Using the product data, a roughness value with a standard deviation was calculated according to German Industrial Standard EN ISO 4287.

The roughness of the matte part (FIG. 1) was measured as R _a = 0.51 ± 0.05 μm. Therefore, the _Ra value is included in the standard range for the decoration color (R _a = 0.3 to 0.6 μ, Table 1), but particularly in the case of a smooth decoration color (R _a ≦ 0.35 μ, FIG. Compared to 5), it is a fairly high number.
Surprisingly, however, the matte feel is smooth and less susceptible to metal wear (which can easily occur as a result of placing a pan or pan on a rough decorative color). This can be explained by comparing the rough conventional ornamental topographic maps illustrated in FIGS. 1-5 with the new matte coating topographic maps. This comparison reveals a clear difference in surface properties. In the case of conventional decorative colors, the ridges are relatively wide (approximately 30-80 μ) and rough (FIGS. 2-5), whereas the ridges in the matte coating according to the invention are needle-like ( The width is approximately 10 to 20 μ) and close (see FIG. 1). Therefore, it is believed that the smooth properties of the matte coating according to the present invention are due to the fact that the surface consists of a very large number of closely spaced fine needle-like tips.

  The black-colored glass ceramic of Seran Supremeer (registered trademark) is described in International Publication WO 02 / 16279A1, the contents of which are included within the scope of the present disclosure.

FIG. 2 is a topographic map of a matte coating according to the present invention on Ceranium Supremeer®. It is a topographical map of “gray”, which is a conventional dark gray decorative color, on Serang Supremeer (registered trademark). FIG. 3 is a topographic map of “Brown”, which is a conventional dark brown decoration color, on Serang Supremeer (registered trademark). FIG. 3 is a topographic map of “black”, which is a conventional black decorative color, on Serang Supremeer (registered trademark). It is a topographic map of “Black 3” which is a particularly smooth black decorative color.

Claims (14)

By forming a glass coating on the ceramic material that is melted in a matte shape on the glass ceramic material, having a softening point higher than 750 ° C. and having a refractive index different from that of the glass ceramic material. A sheet-like glass-ceramic body having at least one matte part, characterized by forming a matte part. The glass ceramic body according to claim 1, wherein the glass is a borosilicate glass having a softening point in a range of 750 to 850 ° C. The glass ceramic body according to claim 2, wherein the glass is a borosilicate glass known as Borofloat (registered trademark), Duran (registered trademark), or Saprax (registered trademark). The glass ceramic body according to claim 1, wherein the glass has an extremely low coefficient of thermal expansion of <7 · 10 ⁻⁶ K ⁻¹ . 5. The glass ceramic body according to claim 4, wherein the glass is known as Borofloat (registered trademark) 3.3 and has a thermal expansion coefficient of 3.3 · 10 ⁻⁶ K ⁻¹ . The glass ceramic body according to claim 1, wherein the difference in refractive index is greater than 0.03. The glass ceramic body according to claim 1, wherein the glass coating is performed by a printing process. 8. A glass ceramic body according to claim 7, wherein the glass coating is applied by screen printing. The glass-ceramic body according to any one of claims 1 to 8, wherein the matte portion has _a roughness of R _a ≤0.6 µm. Preparing an adhesive glass powder comprising a glass melted in a matte shape on a glass ceramic material and having a softening point higher than 750 ° C. and having a refractive index different from that of the glass ceramic material; ,
Applying the adhesive glass powder to a matting target site on at least one side of either a raw glass body or a glass-ceramic body ceramicized from raw glass;
It is composed of a step of firing the adhesive glass powder that has been treated during the ceramization of the raw glass body or a heating step different from the treatment step to the ceramized glass ceramic body.
A method for producing a sheet-like glass ceramic body having at least one matte portion from a sheet-like raw glass body. 11. The silicate glass according to claim 10, characterized in that the glass used is a borosilicate glass, preferably known as Saprax (registered trademark), Duran (registered trademark) or Borofloat (registered trademark). Method. The glass exhibits a paste shape in a standard screen printing medium, and in the case of Borofloat® 3.3, a finely pulverized shape with a particle size of d ₉₉ <10 μm, preferably d ₉₉ <4.5 μm 12. The method according to claim 10 or 11, wherein the method is applied by screen printing. 13. The method according to claim 11 and 12, wherein the composition ratio of the paste is 10 parts by weight of Borofloat (registered trademark) 3.3 glass powder and 12 parts by weight of screen printing medium. 14. Process according to claim 12 or 13, characterized in that the fine grinding of Borofloat (R) 3.3 is carried out by grinding in water to which isopropanol has been added or by grinding in pure isopropanol. .

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