MXPA99003739A - Compositions of lead-free glass and enamel and high content of bismuto, with low point of fus - Google Patents

Abstract

The present invention features low melting point lead-free glass compositions, having a bismuth content of 40 to 70% by weight, an SiO2 content of 24 to 40% by weight and a low or no boron content. , in fact from 0 to 8% by weight. The as-maintained enamel compositions show good preservation properties. The compositions are advantageous for the formation of colored edges on automotive glass

Description

LEAD FREE AND GLASS COMPOSITIONS AND HIGH CONTENT OF BISMUTO, WITH LOW FUSION POINT - DESCRIPTION OF THE INVENTION The invention relates to lead-free glass and enamel compositions with low melting point containing a high content of bismuth and a low or no boron content and showing good preservation properties. Lead-free glass compositions are known in the art. As an example of this, the following may be mentioned: US Patent no. 4 892 847 of Rein erz US Patent no. 4 554 258 of Francel US Patent no. 5 252 521 to Roberts US Patent no. 4 970 178 of Klimas US Patent no. 5 308 803 from Clifford US Patent no. 5 093 285 from Murkens US Patent no. 5 559 059 from Ryan US Patent no. 2 301 100 of Newman US Patent no. 5 629 247 of Prunchak. Other publications on lead-free glass compositions were presented by Francel et al. in the US patent no. 4 446 241, Francel et al. in the US patent no. 4 537 862, Reade in US Patent no. 4 224 047, Eppler in US Patent no. 4 312 951, Eppler in the US patent no. 4 376 169, Emlemdi, in US Patent No. 5 504 045, Mabave et al, in a REF. : 29934 US Patent No. 5578 533 and Evans et al., International Application No. PCT / EP94 / 00403. In addition, attention must be paid to my application for EP 0 895 969 Al. These glass compositions are generally used to form glass frits which would be used for the formulation of glass enamel compositions. These glass enamel (or ceramic) compositions are known to serve for the formation of decorative coatings for glass articles, porcelain and glass for construction and the like. They are especially suitable for the formation of colored edges for glass plates that are used as windshields in cars, parking and reversing lights. These colored edges improve the appearance and avoid the destruction caused by the UV rays of the adhesives that they are below. In general, these enamel compositions consist of the essentials of a glass frit, a dye and an organic carrier. They are applied on the desired substrate and then heated, to burn the organic carrier and melt the frit, whereupon the enamel coating is attached to the substrate. The glass plates for cars are generally coated with ceramic enamel compositions and then subjected to a high temperature forming process. While that treatment melts the enamel and ignites the glass substrate, the glass deforms to its final state. Many coatings according to the state of the art, however, show a tendency to adhere to the materials that cover the mold, such as molds coated with glass or metal fibers, because these common glazes have a lower viscosity after melting and Other materials adhere to higher temperatures. Correspondingly these materials are not suitable for use in glass forming processes, which hot glass enamel coatings come into contact with molds coated with material. Different methods have been proposed to facilitate the formation of glass plates with a ceramic coating, which resist the high bending or formed temperatures and which allow the repeated contact of the glass plate and the molds without adhesion to the molds. For example, the patent documents of US 4596 590 and 4 770 685 (filed by Boaz) and EP 20124 the addition of a low-valent metal oxide powder, for example copper oxide, to dye compositions, to provide an anti-aging layer. adherent between the coating the molding tools coated with glass fibers. The US patent no. 4 684 389, 4 857 096 and 5 037 783 (presented by Boaz) propose the addition of very fine zinc metal powder, to achieve the same effect. The use of a metal iron powder is proposed in US Pat. No. 4,983,196 (filed by Stotka), The use of other metal oxide powders, including bismuth oxide containing formulations, is proposed in US Pat. 4029605 (filed by Kosiorek), 4098949 (filed by Kosiorek), 4892 847 (filed by Reinherz), 4 959 090 (filed by Reinherz), 4 970 178 (filed by Klimas et al.), 5 093 285 (filed by Murkens ), 5 203 902 (filed by Murkens) and EP 370 693 Certain systems containing bismuth however produce a brittle glass, when present eg lithium, and have poor silver diffusion properties as well as unsatisfactory anti-adhesion properties . The patent of US 4 828 596 proposes the addition of copper sulphide or copper sulfate to the ceramic enamel compositions as an anti-adherent material. Sulfides or sulfates of other metals were proposed as anti-adherent agents in the US patent no. 4 822 396 (filed by Reinherz). US patents nos. 5 153 150 and 5 208 191 (filed by Ruderer et al) propose supposedly improved anti-adherent ceramic glaze compositions, in which an inoculated glass powder containing Zn ^ SiO ^ is added in an oxide composition with or without oxide of bismuth. Many of the above ceramic enamel systems use a glass frit containing lead, which is an additional problem. For reasons of environmental protection it is desirable, to avoid the use of any system containing lead. Also when any of the aforementioned enamel systems in the common glass forming process exhibit relatively good productivity, this is not satisfactory enough to be used in the newly developed "deep bend" process to form automotive glass. It is essential that the enamel compositions have an adequate resistance to certain chemical substances, with which they can come into contact, and many of the existing compositions fail in this respect. Each of the previously known enamel compositions suffers from one or more of the aforementioned disadvantages, in such a way that it would seem desirable to present a composition that avoids these inconveniences. The present invention features such ceramic enamel compositions, a process for the use of those compositions and the substrates coated therewith. The present invention presents a composition of glass and glass frits prepared with that composition, which are suitable for the preparation of enamels, which exhibit improved chemical preservation properties of the baked enamel coating. Currently the only lead-free glass frit suitable for automotive enamel, which passes the resistance test to sulfuric acid, which is needed in Japan, for example, uses lithium ions. If the use of lithium is not carefully controlled, it can, however, cause undesirable tensions and ruptures of the substrate. The new glass compositions of this invention avoid that problem. These compositions also exhibit excellent anti-adhesion properties. The present invention presents new glass compositions, which can be obtained glass frits containing bismuth borosilicate, which contain a high content of bismuth but a low boron content or which are free of boron. For these systems it is not necessary to use zirconium dioxide, titanium oxide or lithium oxide in the composition.

The composition according to the invention consists essentially of Bis03 40-70% by weight Si02 24-40% by weight B203 0-8% by weight A1203 0-5% by weight Ti02 0-4% by weight Na20 0- 8% by weight K20 0 - 5% by weight Li20 0 - 4% by weight F'1 0 - 4% by weight It was found that in the course of this report two types of glass compositions have a special significance. The glass compositions according to type I are as follows: The glass compositions according to type 2 are the following: Compositions and v ers are formed in known manner for example by mixing the known starting materials and melting at temperatures of about 1000-1300 ° C for about 40 (forty) minutes, to form a molten glass with the desired composition. The molten glass formed can then be quenched, for example by suddenly cooling with water, to form a frit in a known manner. The frit can then be milled using known milling techniques to a fine grain size, preferably between 2 and 6 microns. The invention features glass enamel (ceramic) compositions, in which the glass frit compositions described above are used. These compositions consist of about 30 to 95% by weight solids of the glass frit component. This component has the components of glass chips presented. That component of glass frits can be used as the only composition of the invention or alternatively as a mixture of those frits. At least one frit of the present invention may be combined with an additional frit of low melting point with a composition different from that of the invention, wherein the proportion of the other frit is limited by the condition that it does not impair the quality of the frit. the resulting enamel composition. An example of that other frit that can be used is one with the following composition: gone Interval in% by weight Si02 20-35 Bi203 10-50 ZnO 5-45 B203 5-15 Na203 1-7 CaO 0-10 Ti02 0- 2 A1203 0-5 Zr02 0-2 F2 0-1 A process for the preparation of such a frit is presented in US Pat. No. 5,346,651. These frits have a firing temperature to ensure adequate adhesion to the substrate. and also show the properties of a low thickness. The glass frit can be combined with a mixed metal oxide pigment, any other type of metal powder, metal precursor or other material of choice. Typically, mixed metal oxide pigments are used to obtain black colors in the automotive industry, such as copper oxide, chromium, iron, cobalt, nickel, manganese and the like. Although these black spinel pigments are preferred for use in the automotive industry, other metal oxide pigments produce different colors, which may be combined with the glass frit compositions according to the present invention. Other end uses may include, but are not limited to, application in the architecture and in the beverage industry. The pigment component generally represents 5 a 40% by weight of the glass frit depending on the desired shade of color, brightness and opacity. Usable pigments are known in the art and can be obtained commercially. Examples of these are among others CuCr204, (Co, Fe) (Fe, Cr) 204 and the like.

For example, the pigments of Cerdee Corporation can be obtained as pigment * 2991, which is a black pigment of copper chromium (III), pigment * 2980 which is a black pigment of iron and cobalt chromate, and pigment * 29- &7 which is a black chromate pigment of iron, manganese and nickel. The enamel composition according to the invention can also contain up to 15% solids, which are generally used as fillers, such as for example silicon dioxide and aluminum oxide, and other common additives., such as for example iron, silicon, zinc and the like, to reinforce the desired properties such as, for example, the diffusion of silver. The fillers can also be a temperature-resistant oxide filler, such as, for example, olastonite and materials such as, for example, aluminum silicate materials, calcium silicate compounds, boroaluminum silicate compounds, sodium-calcium-aluminum silicate compounds, compounds of feldspar, titania and combinations of those oxides. The enamel compositions may contain up to 20% by weight solids of an inoculation crystal material, such as for example bismuth silicate according to EP 0782974 A1, which is covered herein by reference. The inoculated bismuth silicate glass materials include Bi12SiO20, Bi «(Si04) 3, Bi2SiOs, without being limited thereto. The enamel compositions are combined with an organic carrier, to form an easy-to-apply enamel paste. The enamel paste generally contains from about 85 to about 60% by weight solids, as described above and about 15 to 40% by weight of a suitable organic carrier. The viscosity of the paste is adjusted in such a way that it can be applied to the desired substrate by means of screen printing, roller application or spraying. The carrier used in the paste is selected according to its end use. It is essential that the carrier is properly suspended in the solids and that it burns completely when applying heat to the paste. The carriers are typically of an organic nature and include compositions that are based on pine resins, vegetable oils, mineral oils, low molecular weight petroleum fractions, tridecyl alcohols, synthetic and natural resins, and the like. They may also contain surfactants and / or other film-forming modifiers. Correspondingly, UV-based carriers can be used in the present invention. These UV-based carriers are widely known in the art and are generally composed of polymerizable monomers and / or oligomers, which for example contain acrylate or methacrylate functional groups, as well as photoinitiators and polymerization inhibitors. Exemplary systems are presented in US patents no. 4306 012 and 4649062. It is known that these systems harden after their application on the substrate by means of ultraviolet radiation. The specific carrier and the amount used of it are selected according to the specific components of the paste and the desired viscosity. In general, the amount of the carrier is from about 15 to 40% by weight in relation to the total weight of the enamel paste. In general, the enamel pastes have a viscous nature, the viscosity depending on the application method used and the end use. For the purposes of application by means of screen printing, the viscosities of 10 to 80 and preferably 35 to 65 Pa.s at 20 ° Cm are suitable, determined in a Brookfield viscometer, with the rod 7 at 20 rpm. The invention also presents a substrate with an enamel paste according to the invention applied with heat in it. Such a substrate is for example glass, ceramic or other non-porous substrates, and above all automotive glass substrates. Other substrates include facades, devices and containers for beverages. To prepare the enamel compositions according to the invention, the necessary frit (s) are milled to a fine powder using a usual process. The frit component below is combined with gold solid component. The solids are subsequently mixed with the carrier necessary to form the enamel paste. The viscosity is adjusted as desired.

As long as the enamel paste has been prepared, it can be applied to the substrate in a customary manner, such as, for example, by screen printing, application as a decal, spray, broadening or roller and similar procedures. Screen printing is preferred when the paste is to be applied on a glass substrate. After applying the paste to a substrate of any desired type, the coating is fired, so that the enamel adheres to the substrate. The temperature of application of fire is generally determined by means of the preparation temperature of the frit and is preferably in a wide range of temperatures. Typically the fire application temperature for a composition according to the invention is in the range of about 500 to 750 ° C, preferably in the range of about 520 to 650 ° C and most preferably about 530 to 620 ° C. Examples Compositions of low melting point glass frits are prepared by mixing the raw materials which are known in the art, using a method known in the art. The mixtures of well-mixed raw materials are then melted at temperatures between 1000 and 1300 °, then further annealed using a known process for the use of the compound. the glass compositions are subsequently ground into small particles, preferably between 2 and 6 microns using a ball mill. The fine ground powder frits were then used to form glass enamel compositions. The fine ground glass frit is combined with a mixed metallic oxide pigment. After this the solids of the enamel composition are dispersed and suspended in a carrier selected according to the end use, to form an enamel paste. The analysis was carried out in which the glass frits or enamel compositions were combined with a carrier based on pine oil, applying a frit paste or enamel on a carrier object or automotive glass substrate by means of screen printing. The carrier object or automotive glass substrate is subsequently subjected to burning at different temperatures, to determine the "firing temperature" (FT) or "minimum burning temperature" (minimum burning temperature, MF). The FT is the temperature at which the glass has had a sufficient time to flow and melt in the course of a burn for 15 minutes and leads to a bright flat surface. The MF is the temperature at which the enamel has had a sufficient time to flow and melt during a 4 minute burn and leads to an enamel without porosity. The preheating time is 10 or 6 minutes at 427 ° C for FT or MF.

The acid resistance is determined in accordance with ASTM C-724-91, for which a 10% by weight citric acid solution is used. Burned samples are placed during minutes in the solution and evaluated according to the following: Grade 1 No discernible corrosion Grade 2 Color changes or visible coloration of the surface when observed at a 45 ° angle, but not observed when observed with a angle < 30 °. Grade 3 A clear coloration that does not allow the reflected images to be erased and is also observed at angles < 30 ° Grade 4 Clear coloration with a deep color modification or strongly iridescent surface, which is observable at angles < 30 ° and disappear with the reflected images. Grade 5 Surface without gloss or matte with a possible limestone coating. Grade 6 Clear removal of enamel with clear pore formation. Grade 7 Complete removal of the enamel on the treated surface.

Table 1: Formulation of glass frits (% by weight) of type 1 The following automotive enamel formulations were prepared with frits according to examples 2 to 5.

Table 2: Black enamel formulation (% by weight) * 2980 is a cobalt chromate pigment and RD-2077 is a bismuth silicate material. Both materials - can be obtained commercially from Cerdee Corporation; Drakenfeld Products, Westr Wylie Avenue, Washington, Pennsylvani. The anti-adhesion properties were evaluated by means of the enamel on a piece of an automotive glass substrate of 10 x 10 era, heating in a burning cycle of the automotive type of 3 to 5 minutes and pressed with the die of a material commercially used, remaining the hot enamel and the substrate in the oven.

Table 3: Formulation of glass frits (% by weight) of type 2 The following automotive enamel formulations were prepared with frits according to examples 11 to 15.

Table 4: Black enamel formulation (% by weight) * 9 1 - see footnote of table 2 It is noted that in relation to this date, the best known method for the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which the it refers. Having described the invention as above, the content of the following is claimed as property.

Claims (15)

1. CLAIMS 1.- A glass composition, characterized -because it consists essentially of: Bi203 40 - 70% by weight Si02 24 - 40% by weight B203 0 - 8% by weight A1203 0 - 5% by weight Ti02 0 - 4 % by weight Na20 0 - 8% by weight? 20 0 - 5% by weight Li20 0 - 4% by weight F'1 0 - 4% by weight.
2. 2. Composition of glass according to claim 1, characterized in that it consists essentially of: Bi203 40-70% by weight Si02 25-40% by weight B203 0-3% by weight A1203 0-5% by weight Ti02 0 - 4% by weight Na20 0 - 8% by weight K20 0 - 5% by weight Li20 0 - 4% by weight pi 0 - 4% by weight 3. - Glass composition according to claim io 2, characterized because it consists of the essentials of: Bi203 50 - 65% by weight Si02 28 - 38% by weight B203 0 - 2.8% by weight A1203 0 - 3% by weight Ti02 0 - 3% by weight Na20 1 - 6% by weight K20 0 - 1.5% by weight Li20 0 - 1% by weight F "1 0 - 2% by weight 4. - Glass composition according to the claim 2, characterized in that it consists of the following: Bi203 54 - 63% by weight Si02 29 - 37% by weight B203 1 - 2.7% by weight A1203 0.3 -1.0% by weight ti? 2 i - 2% by weight Na20 3 - 4.5% by weight K20 0-1% by weight Li20 0 F'1 0 5. - Glass composition according to claim 1, characterized in that it consists essentially of: Bi203 57-67% by weight Si02 24-37% by weight B203 > 3 - 8 by weight Al2O3 O - 4% by weight Ti02 0 - 3% by weight Na20 0 - 7% by weight K20 0 - 5% by weight Li20 0 - 2% by weight F "1 0 - 4% by weight. 6. - Glass composition according to the claim 5, characterized in that it consists essentially of: Bi203 58-65% by weight Si02 26-35% by weight B203 3.5-7.5 by weight Al203 0-3% by weight Ti02 0-3% by weight Na20 1-6% by weight weight K20 0 - 1.5% by weight Li20 0 - 1% by weight F "1 0 - 2% by weight 7. - Glass composition according to the claim 6, characterized in that it consists essentially of: Bi203 59 - 63% by weight Si02 27 - 34% by weight B203 4 - 7% by weight A1203 0.3 -1.0% by weight Ti02 l - 2% by weight Na20 3 - 4.5% by weight K20 0 - 1% by weight Li20 0 F "1 0 8.- Glass frit characterized in that it is prepared from a glass composition according to one of the claims 7. 9. - Glass enamel paste characterized in that consists of a glass frit component according to claim 8, an oxide pigment component and an organic carrier 10. Glass glaze paste according to claim 9, characterized in that it has a solids content of approximately 85 to 60% by weight 11. Glass glaze paste according to claim 9 or 10, characterized in that the glass frit component also contains one or several different glass frits that melt at lower temperatures. - Glass enamel paste according to one or more of claims 9 to 11, characterized in that it contains up to 20% by weight of solids of an inoculated glass material. 13. - Glass enamel paste according to claim 12, characterized in that the inoculated glass material is bismuth silicate. 14. A non-porous substrate characterized in that a glass enamel paste has been burned on it, according to one or several of claims 9 to 13. 15. A substrate according to claim 14, characterized in that it is a automotive glass.