DD150194A1 - METHOD FOR ADDRESSING GLASS PRODUCTS BY ION DIFFUSION - Google Patents

Abstract

In the visible spectral range, the staining should have significantly reduced selective absorption with good color homogeneity. According to the invention, glassy glasses are brought into contact with silver-containing salt melts at temperatures between 380 and 500 degrees C and subsequently treated with a temperature preferably above the glass transition point. The concentration of the silver ions and the treatment conditions of the glass must be matched to the subsequent temperature treatment. This temperature treatment is preferably carried out during the final shaping or hardening of the glass products. Satisfactory color homogeneity can only be achieved if the contact media are controlled during ion exchange to a maximum concentration of silver-complexing anions and for particularly high demands on the Farbhomogenitaet before the silver diffusion is a treatment with pure potassium nitrate. The colorants according to the invention are suitable for practically color-true reproduction, for example for façade glass, furniture glass, glass doors and hollow glassware as well as for safety glass in motor vehicles.

Description

Application of the Invention _t

The invention enables the targeted dyeing of hollow and flat glasses "With a method according to this invention, shades can be produced without or with significantly reduced selective absorption in the visible spectral range." These shades are suitable because of their aesthetic appearance and virtually color-faithful reproduction in the review B _e facade glass s must meet the physiological functions both for glass products mainly decorative character z _e without optical puncture, safety glass for shower cubicles or glass doors, furniture glass and hollow glass and glass products? / ie Ze gen B * safety glazing in automotive and facade glass _β with viewing function

Characteristic of the known technical solution

The formation mechanism for the formation of shades after silver diffusion into glass surfaces has already been described in general terms by Weyl ("Colored Glasses" Dawson ¹ S of Pall Mall London 1959 $ S * 410) and can be summarized as follows: 1e ion exchange silver against alkali (practical

mostly sodium). 2 Migration of the silver ions from the surface into the interior of the glass

3 β Reduction of the ions to neutral silver atoms 4e Formation of the coloring zones by agglomeration of silver atoms into colloids.

The hues described above for silver diffusion into the glass surface are characterized by a selective absorption in the visible spectral range

For example, DE-OS 2,415,671 proposes a vehicle windscreen whose color, after ion exchange in silver-containing potassium nitrate melts, is characterized by an absorption band between 405 μm and 435 μm.

However, it is known that precisely this increased absorption in the short-wave range does not permit a reliable differentiation of green and blue and can lead to considerable impairment of driving safety, especially in twilight and in foggy weather. Such absorbance curves typical for the absorption of the silver colloids in soda lime silicate glasses are shown in FIG.

The deficiencies in selective absorption has already been pointed out (DD AP 121 096). To remedy this disadvantage, a mass-colored silicate glass with small additions of Se and Co and also Ni and Cr is proposed in this patent. As a result, but at least separate melting units and thus increased effort inevitable.

The practical realization of the ion exchange of silver for sodium on the glass surface is carried out by silver-containing solutions or molten salts. For molten salts, silver nitrate is generally preferred, as well as sodium nitrate and potassium nitrate as carrier media.

For reasons of cost, there are efforts to achieve discoloration of the treated glasses already with low silver concentrations. In fact, under certain conditions, it is possible to produce sufficiently intense hues with a silver ion concentration in the molten salt of about 5 ppm on the support medium.

It is proposed in DE-OS 2,415,671 to control the electrical potential of the molten salt to achieve reproducible shades in the treated glasses ₀ also-in this publication sheet glass is used} which during the float process on the surface with reducing acting tin Ions was enriched »As total content of the reductions» medium in the near-surface area, a minimum concentration of 1.0% by weight is required. B * in colored glasses produced by conventional methods, the proportion of reducing agents on the glass surface is one to two orders of magnitude lower than in float glass, those sheet glasses can not be practically colored by low-silver salt molten salts according to the methods described so far.

In order to obtain sufficiently intensive dyeings even with soda-lime silicate glasses which are produced by conventional processes, hitherto higher silver concentrations and longer pot life have been proposed. In addition, a process for dyeing and simultaneously reinforcing glass is given in DE-OS 2 107, wherein the final coloration after treatment over several hours in pure potassium nitrate at a temperature below the glass transition temperature T sets ». 6

In many cases, the homogeneity achieved in the treatment of the glasses in saline molten salts does not yet satisfy. The control of the electrical potential of the molten salt described above became relative. Movements between glass and molten salt suggested to improve the color homogeneity · The described lack could not be remedied thereby and also the causes for

the unsatisfactory color homogeneity has not yet been elucidated.

The silver nitrate frequently used in salt melts splits off oxygen at temperatures above 250 ^° C. and is thereby reduced to silver nitrite. The silver nitrite decomposes further above 450 ^° C. into nitrogen oxides, nitrogen, oxygen and silver. "This reduces the concentration of silver ions in the molten salt.

In addition to silver nitrate, silver chloride in salt melts is also used as the silver-containing salt. However, it is known from the literature that when exchanged with silver nitrate-containing molten salts at the glass surface, exchange rates of 90 % were achieved for the ion exchange silver versus sodium, while when using silver chloride only exchange rates of 60 % could be measured. Thus, it will be apparent that not all silver compounds used to color glasses are suitable for effective ion exchange in conventional panel glasses.

Object of the invention

The object of the invention, while avoiding the above-mentioned deficiencies, is to provide a method which allows the production of shades with substantially reduced selective absorption in the visible spectral range in a cost-effective manner and with as little effort as possible by diffusion of silver ions into the glass surface, the use of conventional glasses no additional reducing agents in the near-surface area are required

The essence of the invention

The invention provides a process which, after the ion exchange of conventional glasses in silver-containing molten salts and subsequent temperature treatment above the glass transition point T, permits the production of glasses with hues without or with significantly reduced selective absorption * Typical absorption curves of glasses with shades according to the invention are shown in FIGS 2 to products with relatively low Transtnissionswerten (z _e B & furniture glasses, glass doors _s shower stalls) and the Pig Liren 3 and 4 to products with high transmission values (e.g., B * safety glass for cars), "the development of such colors as shown in FIGS 2 The reduction of the silver ions diffused into the glass surface causes the resulting silver atoms to have a specific absorption in the UV region, which extends into the short-wave region of the visible spectral range (see curve 5 "untempered" in FIG 2 ;, ) β Depending on the nature and amount of the reducing glass components as well as the treatment conditions selected, an absorption of varying intensity occurs, which causes a corresponding yellowing _β

With sufficient heat (z * .g. Several hours at temperatures above 350 ⁰ C or correspondingly shorter times at higher temperatures) are formed from the silver atoms in the glass surface gradually Kolloi'öe that cause a typical absorption at wavelengths around 420 Xim *

Erfinclöngsgemäße shades without or with greatly reduced selectivity in the visible spectral range

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By superimposing the remaining absorption on the decreasing portion of the atomic silver with the increasing specific absorption of the silver colloids.

Such shades have a low spectral color content and therefore allow excellent color rendering in the review with a pleasant and aesthetically pleasing appearance · shades according to this method, however, can only produce the silver content practically determined by silver ion concentration and treatment conditions in the contact medium in the glass surface Type and amount of the reducing glass components and the subsequent temperature treatment is tuned ·

For the thermal treatment after the ion exchange, the deformation process in hollow glass as well as the bending process and / or the thermal hardening in safety glass are preferably used. These processes are characterized by low treatment times (about 1 to a maximum of 5 minutes) and temperatures above the glass transition point T. As a result, shades according to the invention can be produced in many glass products without additional process steps and in any case without additional reducing agents.

However, the glasses treated in this way are still unsatisfactory in terms of their color homogeneity. It has been found that with strict control of the contact media upon ion exchange to a maximum concentration of 10 ppm for Br ", <T ~, and CIf" "as well as 100 ppm for Cl ~, a marked improvement in color homogeneity and aging resistance occurs.

The anions mentioned form complexes with silver and thereby impair the ion exchange β at a higher concentration

According to the invention, further improvements in homogeneity are achieved by repeated treatment with the contact medium, since locally inadequate ion exchange is compensated. After each treatment, the adherent salt is from glass _s rinsed with water, the icomplexbildende anions most in these maximum concentrations contains "Also, after the treatment of the glass in rei · = no potassium nitrate before the actual ion exchange with silver, especially in the required vehicle glazing high transmission values It is probable that the potassium ions will compensate for certain structural differences in the glass surface and thus create more homogeneous conditions for the subsequent diffusion of the silver ions. "

Ura to allow effective ion exchange for the production of colored glasses in the context of this invention, the silver compound used must be selected for solubility, degree of dissociation and aging behavior in the carrier medium and thermal stability under the usual treatment conditions and tailored to the Tragermediutn It showed. to _see that the aging of the silver content of the molten salt and Behandlungetemperaturen depends "Above Temperature ^ where metallic silver is produced and generally salt melts at low silver age the contact medium. fast, h »Repeated treatment under the same conditions

conditions leads to decreasing color intensity. Taking into account these results, the contact medium according to the invention preferably consists of potassium nitrate as the carrier medium and silver sulfate or silver nitrate in the concentration range from 0.1 to 5 percent by weight, based on the potassium nitrate. Because of the disintegration properties of the silver nitrate, however, the use of this silver compound must be limited to temperatures below 420 ⁰ C.

Silver sulfate, on the other hand, can even be used above the temperature range customary for low-temperature ion exchange because of its good thermal stability. The process steps for producing glasses whose hues in the visible spectral range have no or only greatly reduced selective absorption and high color homogeneity can be summarized as follows:

1. The cleaning of the glass is preferably carried out with industrial washing machines.

2. If the glass products very high demands on color homogeneity and spectral color content are made, such. As in safety glass for motor vehicles, the cleaned glass is first treated with pure potassium nitrate at temperatures between 380 ⁰ C and 500 ⁰ C.

3. Treatment of the glass with a contact medium containing potassium nitrate as a carrier medium and based on the potassium nitrate from 0.1 to 5 $ 0 weight percent silver sulfate or silver nitrate. The treatment temperatures are for contact media with silver sulfate between 380 ⁰ C and 500 ⁰ C as well as those with silver nitrate between 380 ⁰ C and 420 ⁰ C.

4. The treatment takes place in several successive stages, after which the adhesive salt is rinsed off the glass with water after each treatment *

5 * The treatment of the glass according to the process steps 2j 3 and 4 by dipping or spraying β The cleaning solution according to process step 1 j the salt melts according to the process steps 2 and 3 and the wash water after process step 4 must not contain silver complexing with the above Union Maximum concentration liee

6, "According deoi ion exchange in the silver-containing salt melts, is thermally after-treated, the glass * This post-treatment is carried out during the bending hardness = or deformation process preferably at temperatures between 580 ⁰ C and 640 ⁰ C ₅ thus preferably above the glass transition temperature T ·

Design ispi ele

In all figures the obtained color is characterized by the extinction E, d * h * by the decadic loarithm of the reciprocal spectral transmittance as punctuation of the wavelength * The calculation respectively determination of the spectral transmittance, the normalized chromaticity coordinates, the hue of the same color and the spectral color component refers to standard light C and the visible spectral range from 380 to 780 nm ·.

example 1

Purified Fourcault glass of conventional composition is treated with a contact medium containing as the carrier medium pure potassium nitrate and based on the potassium nitrate 0.008 weight percent chloride and 2.0 weight percent silver nitrate. The glass is immersed for 2 hours at 380 C in the described · bene contact medium and then heated for 4 minutes at 600 G ^0.

Curve 3 in FIG. 2 represents the extinction behavior of the glass colored according to this example. The following parameters were determined for characterizing the color shade:

Spectral transmittance "C = 0.627 Normalized chromaticity coordinates χ = 0.369

y = 0.368 hue wavelength λ = 579 nm

Spectral color fraction ρ = 0.297

The color is not sufficiently homogeneous.

Example 2

Purified Fourcault glass of conventional composition is sprinkled with a contact medium containing pure potassium nitrate, as well as 0.008 weight percent chloride and 2.0 weight percent silver sulfate based on the potassium nitrate. It is sprayed over a period of 40 minutes with said contact medium at a temperature of 400 ⁰ C. The trickling process is used a total of three times, after each irrigation the adhesive salt is rinsed with chlorine-free water. Finally, the glass is tempered for 4 minutes at 600 ° C.

ΛΑ

Curve 4 in FIG. 2 represents the extinction behavior of the glass colored according to this example. The color tone is characterized by the following characteristics ί

Spectral Transtnissiongrad Z: = O ₉ 661 Normalized Color Location Coordinates χ = O _? 36O

y = 0.364 hue wavelength λ = 578 nm.

Spectral color fraction ρ = 0.262

The coloring is sufficiently homogeneous ©

Example 3

Purified Fourcault glass of conventional composition is treated with pure potassium nitrate $ based on the potassium nitrate 0.25 weight percent silver nitrate and 0 _s 008 weight percent chloride contains * The glass is immersed three times for 40 minutes at 400 ⁰ C in the contact medium and Finally, the treated glass is annealed at 600 ° C. for 4 minutes. The extinction behavior of the glass colored according to this example is shown in curve (FIG. 3). "The color tone is characterized by the following characteristics?

Spectral transmittance V = 0,794 Normalized color coordinates χ =? 0.334

y = 0.343 · hue equal to the wavelength ^A f - 576 nm

Spectral color component ρ = 0 _s 136

The coloring is sufficiently homogeneous «

AZ

Example 4 ~ '"

The treatment of the purified Fourcault glass of conventional composition is carried out as in Example 3, but the chloride content is adjusted in potassium nitrate by adding pure potassium chloride to 0.1 percent by weight · The color tone obtained after the annealing of 4 minutes at 600 ⁰ C by the following characteristics characterized:

Spectral transmittance C = 0.723 Normalized color coordinates χ = 0.352

y = 0.358 hue wavelength Ap = 578 nm

Spectral color fraction ρ = 0.227

The coloring is significantly less homogeneous than in Example 3 · The operating time of the ^K ontaktmediums is with increased chloride content only compared to the contact medium of Example 3 half ·

Example 5

Purified Fourcault glass is treated with pure potassium nitrate containing 0.008 weight percent chloride and 2.0 weight percent silver sulfate based on potassium nitrate. The glass is immersed for 20 minutes at 480 ⁰ C in the contact medium, rinsed with chlorine-free water and heated for 3 minutes at 620 ⁰ C · the absorption behavior of the colored glass of this example is shown in curve 6 (Figure 3) ·

dl

The color is characterized by the following characteristics?

Spectral transmittance t "= 0.770 Horsted chromaticity coordinates .χ = 0.338

y = 0.345 hue equal to the wavelength? Sp = 577 nm

Spectral color fraction ρ = 0.151

The coloring is not sufficiently homogeneous

Example S

Purified Fourcault ~ glass is 6 hours at 480 ⁰ C in pure potassium nitrate immersed 0.008 weight percent chloride containing "After that, however, the treatment in potassium nitrate equivalent ^ unit is based on the potassium nitrate with 2.0 percent by weight silver Sulfate The immersion time is twice for 30 minutes at 430 ⁰ G in each case rinsed with chlorine-free water. The final heat treatment is carried out at 620 ^° C. for 3 minutes.

Curve 8 in FIG. 4 represents the extinction behavior of the glass colored according to this example. The color tone is characterized by the following characteristic values ϊ

Spectral transmittance ZT = 0.808 Normalized color coordinates χ = 0.328

y = 0.335 'Hue wavelength' λ = 577 nm

Spectral color fraction ρ = 0.099

The coloring shows good homogeneity.

IH

Example 7 '''

Purified Fourcault glass is immersed for 6 hours at 480 C in pure potassium nitrate containing 0.008 weight percent chloride. Then, the glass is twice immersed for 60 minutes at 380 ⁰ C in a contact medium containing potassium nitrate and related thereto 0.008 weight percent chloride and 2.0 weight percent silver sulfate # The adhesive contact medium is rinsed in each case with chlorine-free 7 / asser. Finally, 3 minutes at 620 ⁰ C is annealed.

Curve 9 in Pigur 4 represents the extinction behavior of the glass colored according to this example. The color tone is characterized by the following characteristics:

Spectral transmittance T = 0.818 formed color coordinates χ = 0.327

y * 0.334 hue at the same wavelength Λ «= 577 nm

Spectral color component ρ β. 0.094

The coloring shows good homogeneity.

Claims (1)

$ 4 Brfindungsanspru. cn Process for dyeing glass products, in which. SiI-ions from a contact medium diffuse into the glass surface characterized in that during the Ionenaustausch.es a fill of the silver ions in the glass only by the contained in conventional glasses ¹ ! Reducing agent is reduced to atoms whose concentration decreases during a subsequent to the ion exchange temperature treatment * while silver colloids are formed and can be realized by superimposing the specific absorption of the silver atoms and silver colloids without or with much reduced selective absorption in the visible spectral rangej Concentration of the silver ions and the treatment conditions of the glass in the contact medium are matched to the final temperature treatment _s wherein iese temperature treatment preferably takes place above the glass transition point Tq . Method according to item 1, characterized in that the glass is cleaned to improve the homogeneity of the dyeing and especially when high transmission values and low spectral Parbanteil is required, a treatment in pure potassium nitrate before the glass is then with a contact medium containing the silver ions _{9 is} repeatedly treated so that the adherent medium after each treatment is rinsed with water, with all media coming into contact with the glass such as cleaning solution, potassium nitrate ₉ silver-containing Kontaktmediuffi and wash water must not exceed the following concentrations for complexing anions: for Cl " maximum 100 ppm and for Br ", J""and Gif maximum 10 ppm" 3 · Expeditions according to items 1 and 2, characterized in that the contact of the media with the glass surface by spraying or sprinkling with a molten salt or solution and by immersion in a solution or molten salt. 4 · Method according to item 1 to 3, characterized in that the silver compound contained in the contact medium and the carrier medium are matched with respect to thermal stability, degree of dissociation and aging behavior, wherein the carrier medium preferably consists of pure potassium nitrate and the silver in the form of silver sulfate or silver nitrate , but preferably silver sulfate is introduced in a concentration range from 0.1 to 5% by weight, based on the potassium nitrate. 5 · The method of item 1 to 4 characterized in that the glass is behan-'delt in the contact media about 10 to 600 min and the range of treatment temperatures is for pure potassium nitrate or silver sulfate-containing contact media 380 ⁰ C to 500 ⁰ C, while silver nitrate-containing contact media, the treatment temperatures between "380 ⁰ G and 420 ⁰ O are to be selected. 6 «method according to item 1 to 5, characterized in that with a final temperature treatment between 400 ⁰ C and about 700 ⁰ C at times between 2 min and 120 min, but preferably above the glass transition T" at temperatures between about 580 ⁰ G and 640th C and times between 2 min and 5 min the desired final color without selective absorption in the visible spectral range can be generated. - m 7 "method according to item 1 to 6 'characterized in that the ₉ required for achieving the final color temperature treatment with the deformation, hardening or bending process is combined» 8. glass articles produced by methods 1 to 7, mainly for decorative purposes Pass _θ Β »glass of passages, glass doors * Shower cabinets or furniture glasses characterized in that the glass articles have a spectral transmittance of O ₉ 50 to O ₉ 75 and a spectral coloring fraction of 0 $ 30 , but preferably have spectral transmittances of 0 _s 60 at a spectral color content below 0 _s 30, have » Se According to the process point 1 to 8 made of safety glass j preferably safety glazings for motor vehicles characterized in that the entire glass article or multi-plate safety glass the outer plate having a color tone without selective absorption in the visible 'spectral region having a spectral transmission degree of 0-70 to 0, 80 and a spectral color fraction of O ₉ 20, but preferably a spectral transmittance of at least O ₅ 75 and a spectral color content of not more than 0.10 ···