RU2793088C1 - Engobe for applying to the surface of glazed porcelain stoneware - Google Patents

Abstract

FIELD: applying coatings to ceramic products.

SUBSTANCE: invention relates to an engobe intended for coating the surface of glazed porcelain stoneware. Engobe for application to the surface of glazed porcelain stoneware contains, in % by weight: feldspar S.GQ.500.EX - 53-55, refractory clay Vesko-Granitik - 14-16, zirconium silicate Zeta Zircon Superfine - 8-12, alumina - 3-5, kaolin enriched with KZhF-2 - 14-16.

EFFECT: improvement of resistance of the surface of products made of porcelain stoneware to heat, increase of their wear resistance and slip resistance.

1 cl, 7 tbl

Description

The invention relates to the field of applying coatings to ceramic products, namely to an engobe intended for coating the surface of glazed porcelain stoneware.

Glazed porcelain stoneware usually consists of three parts: the ceramic base, the engobe applied to the ceramic base, and the glaze applied to the engobe.

At the same time, engobe is a very important part of glazed porcelain stoneware. It acts as a mask for unwanted coloration of the ceramic base before glaze application and at the same time protects from sunlight, and also ensures the water resistance of the surface of the ceramic base. Engobe also prevents possible chemical interaction between the ceramic base material and the glaze material.

In addition, engobe acts as a primer layer, contributing to an increase in the sintering strength of the glaze and ceramic base, which largely determines the properties of the resulting porcelain stoneware product as a whole.

In turn, the glazing design plays a decisive role. The glaze on the surface of the tile is not only a decorative finish, but also especially helps to resist stains, wear and mechanical damage.

Currently, zirconium silicate ZrSiO ₄ (zircon) is most widely used in ceramic products as a sun-protection material. The high refractive index of zircon (1.92) makes it a preferred sunscreen agent. The ceramic base of porcelain stoneware based on clay, feldspar and quartz components often contains zircon itself. For example, a "super white (ultra white)" tile contains 5-8 wt. % zircon, "very white (super white)" tile, contains
3-5 wt. % zircon, tile "white", contains 1-3 wt. % zircon. The composition of engobes and glazes usually contains from 8 to 15 wt. % zircon.

The use of zirconium sun protection agents in ceramic glazes for sanitary ware and ceramic utensils is also mandatory.

From the document (WO 2014016423 A1, 2014-01-30), taken as a prototype, an engobe composition is known, suitable for application to the surface of porcelain stoneware and containing 5-50% wt. ball clay, up to 50% wt. kaolin, 20-50% wt. feldspar, 1-20% wt. aluminum oxide (alumina) and not more than 10% wt. zirconium silicate.

However, the engobe composition of the document (WO 2014016423 A1, 2014-01-30) has some disadvantages. Thus, the known composition does not have sufficient stability when used in products whose surfaces are subject to heating, especially uneven heating. On such a surface, microcracks may appear and, as a result, chipping and rapid wear of the surface of such a product.

Thus, there is a need to improve the resistance of the surface of porcelain stoneware products to heat and increase their wear resistance.

Another problem with the use of ceramic products that needs to be addressed is their low slip resistance.

The task is solved by the proposed engobe for applying glazed porcelain stoneware to the surface, which contains:

feldspar S.GQ.500.EX 53-55 wt. % refractory clay Vesko-granitik 14-16 wt. % zirconium silicate Zeta Zircon Superfine 8-12 wt. % alumina 3-5 wt. % kaolin enriched with KZhF-2 14-16 wt. %.

The technical result of the invention is to improve the resistance of the surface of products made of porcelain stoneware to heat, increase their wear resistance and slip resistance.

Feldspar S.GQ.500.EX is mined in Turkey by Kaltun (http://www.metachim.com/products/glasstun/Sodium%20Feldspar/, publication date verified via Internet archive Waybackmashine, 05/28/2016) and has a chemical composition (wt.%), indicated in Table 1:

Table 1

The chemical composition of feldspar S.GQ.500.EX:

_{SiO2 Al2O3 _ Fe2O3 _} CaO MgO _{Na2O K2O} L.O.I Norm. 69.52 18.55 0.040 0.75 0.07 10.60 0.22 0.25 Min. - 18.00 - - - 10.00 - - Max. 70.50 - 0.060 - - - - -

Refractory clay Vesko-granitik is mined in the Andreevsky deposit by the Donetsk company "Vesko" and has the mineralogical and chemical compositions disclosed in Table 2 and Table 3:

table 2

Mineralogical composition of refractory clay Vesko-granitik:

free silica Muscovite Nasrit Rutile Siderite 32-39 38-44 20-25 0.6-0.7 0.2

Table 3

Chemical composition of refractory clay Vesko-granitik:

Al ₂ O _3, not less than, % Fe ₂ O ₃ + TiO ₂ no more, % MgO no more, % CaO no more, % K ₂ O not less than, % Na ₂ O no more than, % SiO ₂ not normal, % P.P.P., % 28 2.35 0.60 0.50 2.10 0.40 63 8.5

The information indicated in Tables 2, 3 is given in the article by Moshnyakov M.G. "Russian clay deposits and the possibility of their use for import substitution of raw materials in the production of ceramic granite", published in the Bulletin of the BSTU. V.G. Shukhova, 2016, number 4, pp. 60-65.

For the purposes of the present invention, a zirconium silicate with the following characteristics is required, as shown in Table 4:

Table 4

Chemical composition of zirconium silicate

ZrO ₂ +HfO _{2 SiO2} total SiO ₂ free Fe2O _{3 TiO2 Al2O3 _} CaO _{P2O5 _} Th+U 65.5-66.5 31.8-32.8 0.05-0.10 0.04-0.12 0.12-0.5 0.75-1.0 0.02-0.5 0.1-0.13 <470ppm

The composition shown in Table 4 is possessed by finely ground zirconium silicate Zeta Zircon Superfine, the country of origin of which is Germany (Internet page https://ceramgzhel.ru/katalog/syiryo/silikat-czirkoniya/2014.html, publication date, confirmed using the Internet service archive Waybackmashine, 09/27/2020).

Enriched kaolin grade KZhF-2, the chemical composition of which is given in Table 5 00284530-00kaolinobogashhennyjdljakeramicheskikhizdelij.pdf, date of publication, confirmed using the Internet archive Waybackmashine service, 06/05/2016), is implemented by Plast-Rifey LLC, which develops the Zhuravliny Log deposit.

Table 5

The chemical composition of kaolin enriched with KZhF-2:

Al ₂ O ₃ , not less, wt.% SiO ₂ , no more, wt.% Fe ₂ O ₃ , no more, wt.% TiO ₂ , no more, wt.% K ₂ O, wt.% Na ₂ O, wt.% CaO, no more, wt.% P.P.P. 36 46-48 0.8 0.4 0.7-1.5 0.06 0.11 13-13.7

Engobe is prepared by joint grinding 53-55 wt. % feldspar S.GQ.500.EX, 14-16 wt. % refractory clay Vesko-granitik, 8-12 wt. % zirconium silicate Zeta Zircon Superfine, 3-5 wt. % alumina and 14-16 wt. % enriched kaolin KZhF-2 in a batch mill MTD 050 for 6-7 hours.

When grinding, water and electrolyte are added to the mixture of raw materials to obtain a finished engobe in the form of a suspension with the specified parameters of the residue on a sieve of 45 μm, the density and fluidity of the suspension.

Moreover, the residue on a sieve of 45 microns should be 1-1.2%, the density of the engobe suspension is 1.7-1.75 g / ml, and the fluidity is 35-40 sec.

After the specified parameters have reached the set values, the finished engobe is poured into a storage tank with a volume of 5 m ³ .

For transportation of the finished engobe, containers with a volume of 1 m ³ are used. After pouring the engobe into transport containers, it is transported to the glazing line.

On the glazing line, the engobe is brought to the working density with water, set by the launch map for a particular article of porcelain stoneware products. This ensures the uniformity of application and the necessary parameters of the finished product.

Engobe is applied to the porcelain stoneware base using an Airless unit at a pressure of 8-10 bar.

As examples of the use of the proposed engobe, methods for manufacturing porcelain tiles are given.

Example 1

According to the above method, a suspension of the proposed engobe containing 55 wt. % feldspar S.GQ.500.EX, 14 wt. % refractory clay Vesko-granitik, 12 wt. % zirconium silicate Zeta Zircon Superfine, 4 wt. % alumina and 15 wt. % enriched kaolin KZhF-2. At the same time, additionally, the composition of the suspension includes water and electrolyte, which are introduced in the required amount to achieve a suspension density of 1.75 g/ml.

On the glazing line, engobe is brought to a working density of 1.5 g/ml with water.

The finished engobe suspension is applied to the ceramic base of the tile. In this case, the consumption of angobas suspension is 35 g per tile 300x300 mm.

After drying the engobe, a glaze composition (made in Italy) with a density of 1.4 g/ml is applied to the tile. The consumption of the glaze composition is 30 g per 300x300 mm tile.

The raw tiles are then sent to the kiln. Roasting is carried out at a temperature of 1205 °C.

The finished tile was tested according to the methods, according to GOST 27180-2019 p.14.

According to the inclined plane method, the slip resistance of ceramic tiles was determined (GOST 27180-2019 p. 14.3). An inclination angle of 7.5 degrees was obtained, which corresponds to the slip resistance class R9.

The scope of such tiles are dry rooms, for example, medical offices, entrance areas of shopping malls, etc.

The wear resistance of glazed tiles was also measured (GOST 27180-2019 p. 9). The number of revolutions was obtained, after which visible changes were found, equal to an average of 2100, which corresponds to wear resistance class 4. The characteristic of the class is high wear resistance.

The scope of tiles with such characteristics according to GOST 13996-2019 are floor coverings of premises with a certain amount of abrasive pollution, regular walking, and with loads greater than for class 3 (for example, industrial kitchens, hotels, exhibition and retail premises).

Comparative parameters of the proposed composition of engobe, and engobe, which was used earlier, applied under the conditions according to example 1, are shown in Table 6.

Table 6

Name of indicator Previously used engobe Engobe according to the invention Slip resistance of ceramic tiles (GOST 27180-2019 p. 14) according to the inclined plane method tilt angle 3.2 deg.
slip resistance class - NC tilt angle 7.5 degrees.
slip resistance class - R9 Wear resistance of glazed tiles 1500 rpm
wear resistance class - 3 2100 rpm
wear resistance class - 4

Example 2

According to the above method, a suspension of the proposed engobe containing 53 wt. % feldspar S.GQ.500.EX, 16 wt. % refractory clay Vesko-granitik, 12 wt. % zirconium silicate Zeta Zircon Superfine, 4 wt. % alumina and 15 wt. % enriched kaolin KZhF-2. At the same time, additionally, the composition of the suspension includes water and electrolyte, which are introduced in the required amount to achieve a suspension density of 1.7 g/ml.

On the glazing line, engobe is brought to a working density of 1.35 g/ml with water.

The finished engobe suspension is applied to the ceramic base of the tile. In this case, the consumption of engobe suspension is 40 g per tile 300x300 mm.

After the engobe has dried, a glaze composition (made in Italy) with a density of 1.4 g/ml is applied to the tile. The consumption of the glaze composition is 25 g per 300x300 mm tile.

The raw tiles are then sent to the kiln. Roasting is carried out at a temperature of 1210 °C.

The finished tile was tested according to the methods, according to GOST 27180-2019 paragraphs. 9 and 14.

According to the inclined plane method, the slip resistance of ceramic tiles was determined (GOST 27180-2019 p. 14.3). An inclination angle of 14 degrees was obtained, which corresponds to the slip resistance class R10.

The scope of such tiles are public areas with the likelihood of water ingress and short-term stay of people. This applies to locker rooms in swimming pools, halls of cafes, restaurants, etc., where wet cleaning is done several times a day, as well as to public buildings.

The wear resistance of glazed tiles was also measured (GOST 27180-2019 p. 9). The number of revolutions was obtained, after which visible changes were found, equal to an average of 2100, which corresponds to wear resistance class 4. The characteristic of the class is high wear resistance.

The scope of tiles with such characteristics according to GOST 13996-2019 are floor coverings of premises with a certain amount of abrasive pollution, regular walking, and with loads greater than for class 3 (for example, industrial kitchens, hotels, exhibition and retail premises).

Comparative parameters of the proposed composition of engobe, and engobe, which was used earlier, applied under the conditions according to example 2 are shown in Table 7.

Table 7

Name of indicator Previously used engobe Engobe according to the invention Slip resistance of ceramic tiles (GOST 27180-2019 p. 14) according to the inclined plane method tilt angle 6.5 deg.
slip resistance class - R9 tilt angle 14 degrees.
slip resistance class - R10 Wear resistance of glazed tiles 1500 rpm
wear resistance class - 3 2100 rpm
wear resistance class - 4

Thus, thanks to the use of the proposed engobe composition, it became possible to obtain glazed porcelain stoneware tiles with increased wear resistance and increased slip resistance.

Claims (2)

Engobe for applying to the surface of glazed porcelain stoneware, characterized in that it contains, wt.%: feldspar S.GQ.500.EX 53-55 refractory clay Vesko-granitik 14-16 zirconium silicate Zeta Zircon Superfine 8-12 alumina 3-5 kaolin enriched with KZhF-2 14-16