WO2016048259A1

WO2016048259A1 - Surface technology generated with a single firing in ceramic sanitaryware products

Info

Publication number: WO2016048259A1
Application number: PCT/TR2015/050113
Authority: WO
Inventors: Serkan YENER; Emrullah KUMCULAR
Original assignee: Matel Hammadde Sanayi Ve Ticaret AS
Current assignee: Matel Hammadde Sanayi Ve Ticaret AS
Priority date: 2014-09-23
Filing date: 2015-09-21
Publication date: 2016-03-31
Anticipated expiration: 2017-03-23
Also published as: GB2546443A; GB201706385D0

Abstract

The present invention relates to a unstainable and easy-to-clean, antibacterial surface technology / Hygiene glaze which is used in ceramic sanitaryware products obtained with a single sintering (firing) process by means of oxides that are prepared from transparent frit having a 40-45% albite, 25-30% quartz, 3 - 7% calcite, 5 - 10% dolomite, 1 - 3,5% ZnO and 2 - 5% B₂O₃ based composition by weight having a melting factor of 27,7 F.

Description

SURFACE TECHNOLOGY GENERATED WITH A SINGLE FIRING IN CERAMIC SANITARYWARE PRODUCTS

DESCRIPTION

TECHNICAL FIELD

The present invention relates to a surface technology which is used in ceramic sanitaryware products, unstainable and easy-to-clean, antibacterial and obtained with a single firing.

STATE OF THE ART

Ceramic sanitaryware products are a ceramic branch consisting of washbasin, closet, squatting pans, shower trays, reservoir and pedestals. Slip and glaze recipes prepared according to a certain composition are used in production. Shaping is performed by casting and the product is obtained with sintering (firing) step finally. The fired product is tested according to specified standards and supplied to end users.

The most important surface characteristic required in ceramic sanitaryware products is that it is easy-to-clean and hygienic. Different methods are used for this purpose. Applying chemicals with a certain mixture having hydrophobic characteristic to the product's surface is the most known application expressed as cold application (unsintered application). This application disappears off the surface after a certain period of time following use. Another application is to enable the glaze having a specific recipe to adsorb on the surface onto a qualified product by sintering. Errors occurring in the fired product as a result of repeated firing cost and repeated firing are disadvantage of this application having permanent characteristic. In previous applications carried out in order to provide easy-to-clean characteristic to the surfaces of ceramic sanitaryware products, aqueous chemicals having hydrophobic characteristic are used in the surface. However, due to the fact that there is no direct diffusion to the surface in these applications, it is known that this characteristic disappears off the surface after a certain period of time following use. Another application is applying a new glaze having a specific recipe onto the final product fired and sintering it. Errors arising from refiring and the costs causing from repeated firing occur here as well. Antibacterial ceramic surfaces are obtained again by including silver ions with nano-size into the glaze recipe. These characteristic can never be provided on a single surface.

The European patent application titled as "glaze compositions" and having a publication number of "EP0509792" is document in the state of the art. This application discloses the fact that it does not contain lead, cadmium and toxic heavy metals; an essential compound composition; and a glaze composition which is formed by firing these compounds at a temperature of between 950 to 1250°C. In this technique, it is not possible to obtain the said composition with a single firing. In addition, it is required to perform surface applications separately in this technique so as to provide characteristics of unstainable, easy-to-clean, antibacterial.

Another document in the state of the art is the International patent document having a publication number of WO2004/031087. In this technique, the surface coating consists of transparent frit in the ratio of 90-100%. Oxide content of this frit is also in the form of Si0₂ (in the ratio of%45-60), A10₃(in the ratio of%5-15), CaO (in the ratio of%4-10), N₂0 (in the ratio of% l-4) and B₂0₃ or Na₂C0₃ (in the ratio of% 10-22). This glaze (surface coating) is a glaze suitable for second firing. Because when melting factors of oxides are calculated, they have a melting factor higher than current opaque glaze. Due to the fact that melting factor is high, it is required to perform second firing at lower temperatures (1140-1170 C°). It is carried out as such in the study having application no. WO 2004/031087. The fact that the second firing (double firing) has a high cost and error rateoriginating from second firing increases total cost in manufacture of products and it is a significant drawback experienced. Consequently, because of the above-stated drawbacks and current solutions are insufficient about the said matter, there is a need for a new production technique and product concerning surface coating of products used in sanitaryware products in ceramic industry. DESCRIPTION OF THE INVENTION

The present invention relates to a novelty for surface coating of ceramic sanitaryware products in ceramic industry which meets the above-stated requirements, eliminates all disadvantages, and provides some additional advantages.

An objective of the present invention is to eliminate disadvantages of current applications. It is aimed to develop a glaze composition which gathers all characteristics in a single product and most importantly, can carry out these in a single firing.

Another objective of the present invention is to ensure making double glaze application. A further objective of the present invention is to obtain a new glaze which has a higher angle of contact on zirconia-based bright opaque glaze used in production.

A yet further objective of the present invention is to ensure that sintering (firing) process of this kind of applications, which can be obtained with double sintering (firing) in current applications, is provided with a single firing. Application of surface coating, which is used in current technique, in first firing makes this impossible due to the fact that melting factor is high. This causes some problems like pinholes or over fired surface image on the products. Therefore, it is impossible to use this surface coating. Sintering degree of the glaze required to be 5 developed so as to carry out sintering with first firing should be in the range of 1180°C - 1210°C, which is the first sintering temperature. For this purpose, a new glaze composition which can be sintered with first firing, and which is again for an unstainable, easy-to-clean, antibacterial and smooth designed. The Hygiene glaze developed for this purpose consists of 40-45% albite, 25-30% quartz, 3-7%

10 calcite, 5-10% dolomite, 1-3,5% ZnO and 2-5% B₂0₃ based transparent frit by weight. When melting factors of oxides inside this glaze are calculated, it is seen that they have a melting factor lower than surface coatings in the state of the art. Melting factor of hygiene glaze is 27, 7F. This glaze, developed according to this melting factor is suitable for first firing (single firing). Thus, sintering is provided

15 with a single firing.

% oxide values of the new Hygiene glaze developed and the current glaze used in the current technique obtained with XRF method are indicated in the following table.

20

CURRENT

58,34 10,88 0,12 0,07 8,10 1,72 4,23 0,93 0 6,19 1,5 7,97

GLAZE

TABLE - l:Compositions of New glaze and Current glaze in percentage by

weight

5 In addition, the table of weight values by percentage of the newly developed glaze

and the current glaze in mole are in the following.

TABLE - 2:Weight values in mole %

When both tables are examined, the most important noticeable difference is that the new glaze comprises B₂0₃ but no Zr0₂ in it. Glazes not comprising Zr0₂ have the characteristics of transparent and they ensure that the surface becomes smooth by covering particularly zirconium crystallizations arising out of the lower current glaze during sintering.

Figures facilitating to describe the invention

Figure-lit is SEM image of the fired reference glaze surface. Figure-2It is SEM image of the newly developed glaze surface taken after firing.

Figure-lit is image of the stated current reference surface under scanning electron microscope. Crystallizations on the surface lead to staining and prevent being easy-to-clean.

Figure-2It is scanning electron microscope image of the Hygiene glaze, developed which is developed on the current reference surface, obtained with a single firing after being fired together. As is also understood from the surface, the Hygiene glaze hides the crystallizations in the under glaze. Thus, it prevents the surface from keeping stain and ensures being easy-to-clean.

In addition, the fact that the newly developed glaze has a high ZnO content and comprises B₂0₃ensures contact angle value of the final recipe is higher than the current glaze. The fact that the contact angle value is higher than the current glaze ensures that stains cannot remain on the surface and provides being easy-to-clean. Measurements of contact angle are also stated in the following table.

TABLE 3: Measurement values of contact angle of the current glaze and the Serel

Hygiene glaze When measurements of either chemical analysis values or contact angle are examined it can be seen that a recipe necessary for an unstainable and easy-to- clean surface is obtained. In order to also give antibacterial characteristic to this new surface, a nano-size Ag+ ion was added. The nano-size silver powders added do not affect physical, chemical and sintering behaviors of the final recipe affect in a negative way and they also provided antibacterial (bacteria-free) characteristic to the new surface. Thus, the glaze developed became an unstainable, easy-to-clean, and antibacterial glaze. The step after developing the new glaze is to be able to obtain this new glaze in the form of a double-layered glaze (the current glaze below, the new glaze above) with a single firing differently than equivalent applications. As is known, these unstainable and easy-to-clean surfaces can be provided double firing in the world in the sector of ceramic sanitaryware products. Our aim is to reduce this to a single firing with the surface technology composed with a single firing in the inventive ceramic sanitaryware products. The biggest difficulty in firing double layered glazes together is that both glazes move like a mutual glaze as diffused into each other during sintering. In order to prevent this during sintering, it is ensured that the new glaze starts to be developed and covers the surface with a thin layer (thickness of the current lower glaze is 750 microns) in the thickness of 100 microns after the sintering of the current glaze is completed by keeping the melting temperature of the Hygiene glaze higher than the current glaze. There is no pre-firing in the production technique of the Hygiene glaze. Products of ceramic sanitaryware products are normally glazed with an opaque bright glaze at first and then the Hygiene glaze developed by us is applied on this glaze. Glaze thickness of the Hygiene lower is aimed to be at around 100 microns. Then, the product is sintered (fired) at a single step. The important point in this study is that the invention is realized with a single step. When melting factors of the current glaze and the new glaze developed are calculated according to the oxide values that they comprise, it is seen that the current glaze starts melting at an earlier temperature; accordingly, the new glaze provides development later. (Melting factor can be obtained from SEGER analysis calculation.)

TABLE 4:Comparing Melting Factors

One of the most important factors in order to obtain double glaze application is that physical characteristics of the new glaze applied as upper layer are different than the lower glaze. Physical characteristics of the glaze were changed in order to obtain a thin transparent layer at 100 micron levels on the surface; accordingly a glaze with a lower liter weight was obtained. Liter weight of the current glaze and the new glaze cam be seen in the following table.

TABLE 5 : Liter weights

The new glaze having low liter weight (intensity) is an important parameter for eliminating surface problems after sintering. Consequently, this type of surfaces which can be obtained with double firing in current applications is provided with a single firing by means of our study. An unstainable, easy-to-clean, and antibacterial (bacteria-free) surface is obtained with the new glaze developed. Thus, a surface technology comprising three characteristics together occurs. In addition, the new surface developed is permanent on the surface of ceramic sanitaryware products.

Claims

A production method for surface technology / Hygiene glaze composed with a single firing in ceramic sanitaryware products comprising % 65,07 Si0₂, % 0,11 Fe0₃, % 11,92 A1₂0₃, % 0,07 Ti0₂, % 5,99 CaO, %1,58 MgO, % 4,88 Na₂0, % 0,18 K₂0, % 0,81 B₂0₃, % 0,01 Zr0₂, % 2,5 ZnO, % 7,12 L.O.I by weight; characterized in that it is obtained with a single sintering (firing) process by means of oxides prepared from transparent frit that has a 40-45% albite, 25-30% quartz, 3-7% calcite, 5-10% dolomite, 1-3,5% ZnO and 2-5% B₂0₃basedcomposition by weight having a melting factor of 27,7 F.

A production method for surface technology / Hygiene glaze composed with a single firing in ceramic sanitaryware products according to Claim 1, characterized in that providing the characteristic of unstainable and easy-to- clean is ensured with sintering method.

A production method for surface technology / Hygiene glaze composed with a single firing in ceramic sanitaryware products according to Claim 1, characterized in that Ag⁺ion is added into the composition in order to ensure characteristics of unstainable and easy-to-clean, antibacterial with a single glaze composition.