DD153360A1 - MATTRESS PASTE FOR GLASS - Google Patents

Abstract

The invention relates to a matting paste for glass, in particular suitable for application by means of the screen printing process for matting or marking glass. The aim of the invention is to provide a matting paste for glass with an adjustable matting effect and such properties, which make it suitable for an economic use in screen printing and also causes an increase in strength of the glass treated therewith. The paste according to the invention consists in mass% of NH deep 4 HF deep 2 10 ... 50; KHF and / or KF 5 ... 50; KBF deep 4 1 ... 15; SnCl deep 2 1 ... 5; HF and / or H deep 2 SO deep 4 5 ... 25 and alkali fluoro-silicates and / or Alkalifluoroaluminaten for pasting, fluorine-free aggregates, microcrystalline cellulose in solid and suspended form, glycerol and carboxymethyl cellulose. The invention can be applied to all hollow and Flachglaesern for applying patterns or markings.

Description

JS. A

Applications of the invention

The present invention relates to the matting or marking of glass, in particular by means of the screen printing method O.

Characteristic of the known technical solutions

The matting or marking of glass is carried out with different pastes or solutions, known matting substances usually containing HF (especially in the case of solutions) and ML.EEV (especially in the case of pastes) as active components. According to Bachtik and Pospichai (in: Oblagorazivanie stekla, Izd literatury po stroitel'stvu 1970, pp. 183-185) and Altmann (in: The new textbook of glass etching, Verlag A _e W ₈ Gentner 1963, Se 49 - 51) To adjust the viscosity, thickeners such as wheat flour, dextrin, starch, water glass, CaSO 4, BaSO 4 are added to the pastes to adjust the viscosity, and fluorochemical additives such as CaF ₂ , Na ₂ SiFg and Na ₂ AlIV are added to improve the etching properties.

Such matting substances have the following disadvantages:

- The exposure times to achieve a matting or marking effect at room temperature are often 5-10 minutes or even longer.

- If work is carried out at higher temperatures to reduce the exposure time, environmental pollution from fluorine-containing gases occurs.

- The shelf life is relatively low, especially with additions of wheat flour, dextrin and starch, and by segregation of the ingredients are sometimes unsatisfactory Standseiten.

- It is not possible to set a defined matting effect in the sense of, for example, matt, semi-matt or silk-tinted tints.

The strength of the matting effect is not sufficient enough, where the term strength is to be understood as meaning the impact resistance on delustrations of larger areas (eg of table glass) and the abrasion resistance on markings of smaller areas (eg, of container glass).

Matting or marking with modern methods, for example by means of screen printing, is only possible with increased effort; Bachtik and Pospichal recommend additional pressure with glycerine to achieve the required printing accuracy. The advantages of high-performance automatic screen printing machines can not be effective, because according to Bachtik and Pospichal, a contact time of 3 minutes is required for screen printing; Altmann even requires 5 minutes.

Object of the invention

It is a matting paste for glass with an adjustable matting effect and such properties are created, which allows matting or marking economically favorable screen printing and causes increased strength of the matting or marking.

Explanation of the essence of the invention

The invention has for its object to provide a matting paste for glass, which has an adjustable matting effect, the matting or marking undergoes increased strength and is particularly suitable for screen printing.

According to the invention the object is achieved in that the matting paste in mass -% off

NH ^ HP ₂ 10 ... 50

KHF ₂ and / or KP ₂ 5 ... 5O

KBF ^ 1 ... 15

SnCl ₂ 1 ... 5

BF and / or H ₂ SO ^ 5. » _e 25

consists, for pasting .Alkalifluorosilikate and / or Alkalifluoroaluminate and fluorine-free additives with low, adapted to the screen size grain size for adjusting the viscosity contains. The addition of microcrystalline cellulose in suspended Fora in an amount of 15 ··· 50 % by mass surprisingly forms thixotropic properties of the matting paste heEUs, a characteristic essential to a good screen printing paste. A high printing accuracy, the z. B. is required for labeling of container glass, and good adhesion of the matting paste is achieved by adding glycerol in an amount up to 10 % by mass and / or microcrystalline cellulose in a suspended form

An improvement of the homogeneity and service life of the mattie: Eungspaste is achieved, if it contains besides the microcrystalline cellulose still Carboxyaethylzellülose in an amount of O, 2..eO, 5 mass % .

The matting effect is due to the change in the ratio of the components NK ^ HF ₂ vxiä. KHE ₂ and / or KF adjustable. If, for example, the matting paste contains only NH ₂ HF ₂ as the etching substance, icy to matt matting effects are achieved, while with a relatively high content of KHF ₂ as the etching substance, silky tints are achieved.

The most favorable for the particular processing case viscosity can be by the addition of BaSO ^, and / or polyvinyl alcohol and / or microcrystalline cellulose in solid form, but also by adding fluorine-containing additives such as alkali metal fluorosilicates in an amount of 5 ·· <Λ0 mass -% and / or Alkalifluoroaluminate in an amount of 5 ·· »20 % by mass.

The content of 1 to 10 % by weight of KBF in the matting paste leads to a higher strength of the matting effect. The reason for this is the diffusion of Ealiumionen in the GIasoberfläche * Decisive for a good diffusion of the potassium ions is a high degree of dissociation of the potassium compounds,

Depending on the composition of the matting paste or the matting effect to be achieved, therefore, HpSO ₄ will give rise to a high degree of dissociation. Furthermore, in order to improve the potassium ion diffusion of the delustering paste according to the invention, SnCl _{2 is added} in an amount of from 1 to 5% by mass. The effect of SnCl ₀ is based on the polarizability of the

Sn ions through the glass surface and promotes the migration of potassium ions into the glass surface layers.

Exemplary example

The following four compositions (specification of the components in % by mass ) of the matting paste according to the invention were prepared and applied by screen printing to glass samples measuring 9 cm χ 11 "cm:

Matting 1 5 2 3 - Mr. 1.8 30 NH ₄ HF ₂ 30 5 10 25 0.3 KHF ₂ - 18 33 - KF - 2 7 20 KBF ₄ 20 3 5 SnCl ₂ 0.2 1.8 3 glycerin 5 - HF 10 9.7 H ₂ SO ₄ - microcrystalline cellulose in suspended form (commercial product Heweten 30) 20 Carboxymethylzeliülose 0.2 ' Na ^ AUV 10

K ₂ SiF ₆ 18 - ~

BaSO ^ - E-. - 10.6

microcrystalline

Cellulose in solid form

(Commercial product Heweten

201) - - 7

The four matting pastes have the following essential properties or lead to the following changes in the glass properties:

Matting paste no.

thixotropy sufficient sufficient Well very well Exposure time in s 60 60 40 60 Tint of matting effect frosted silky matt semi-dull frosted average impact strength in J 0.54 0.62 0.54 0.59

The viscosity of the mentioned matting pastes was adjusted according to empirical values of customary screen printing pastes and is therefore comparable, irrespective of the substance predominantly used for adjusting the viscosity. In particular, due to the thixotropic properties and the shorter egg times, the matting pastes are very well suited for the screen printing process from a technological and economic point of view.

To determine the increase in strength, impact tests were carried out on at least 25 frosted glass samples measuring 9 cm χ 11 cm with a 0.044 kg ball from increasing drop height until the disc broke, with the matted surface being subjected to tensile stress. The average impact strength is defined as the one at which 50% of the samples break.

Comparative measurements with matting pastes according to the literature led to the following results:

Matting paste after middle punch

strength in J

Bakhtik and Pospichal 0,39

(40 mass% NH _a HF _P , 40 mass% NAlFS 20 mass% HF)

Glass Reviews Send Keramo technology

(1966) 1, p. 37

(Saturated solution of NHJBFp

in HF with BaSO, and glycerine

thickened) 0.39

Glass-enamel ceramic technique 1_§

(1965) 12, p. ₈ 495

(69 mass% NH.HFp, 30 mass%

Glycerine, 1 mass% HF) 0.42

Untreated sheet glass (not matted) has an average impact strength of 0.38 J.

Claims (5)

J ** E r f ind tmgs an s ρ r u ch 1 ... 15 SnCl ₂ 1. ·. 5 HF and / or H ₂ SO ^ 5 ... 25 is the matting effect by changing the ratio of the components NH ^ HF ₂ and KHF ₂ and / or KF is adjustable, for pasting Alkalifluoroailikate and / or Alkalifluoroalutninate, preferably K ₂ SiF ₅ and / or Na ₃ AlF ₅ and Na ₂ SiF ₅ and / or contains K ₃ AlF ₅ , fluorine-free additives having low screen-sized particle size, preferably BaSO 4 and / or polyvinyl alcohol, and / or microcrystalline cellulose in solid form for adjusting the viscosity and microcrystalline cellulose in suspended form for forming thixotropic properties, the matting paste for improving the homogeneity, service life and adhesive strength of glycerine and / or microcrystalline cellulose in suspended form and carboxymethylcellulose and to achieve increased strength of the matting effect, a high degree of dissociation of the potassium compounds used and increased migration of the potassium ions into the glass surface layers available. 1. matting paste for glass, especially for screen printing, characterized in that the matting paste in mass ~% of the components 10 ... 5O T C KHF and / or KF 5 ... 5O 2, matting paste for glass according to item 1, characterized in that the Alkaiifluorosilikate and / or Alkalifluoroaluminate in an amount of 5, 2O mass -% are added. 3 * matting paste for glass according to item Λ _9, characterized in that the fluorine-free additives are added in an amount of 5 "× 40% by weight» 4 «Matting paste for glass according to item 1, characterized in that microcrystalline cellulose is added in an amount of 15 × 5 × mass% 5 "Matting paste for glass according to item 1, characterized in that glycerine is added in an amount of 0 to 10 % by mass and carboxymethylcellulose in an amount of 0.2" to 0.5 % by mass " 6 _e matting paste for glass according to item 1, characterized in that carboxymethyl cellulose is used in particular when using microcrystalline cellulose in suspended form. "Matting paste for glass according to item 1, characterized in that KBF ^ and SnCl _{2 are added} to increase the strength of the matting effect in the stated amounts *