DE1040198B - Process to increase the chemical resistance of glass objects - Google Patents

Description

GERMAN

The invention relates to a method for treating glass objects made of alkali-lime-silica glass as well as glazed and enamelled objects to increase chemical resistance of glass, glaze and enamel.

The ordinary alkali-lime-silica glass possesses under certain circumstances an insufficient chemical and thus also weakened mechanical Resilience; it is not entirely resistant to water vapor, which is why it does so over time is also weakened mechanically. This is due to the fact that the alkali content is close the glass surface can be leached out of the air by condensed moisture. These disadvantages of the alkali-lime-silica glass can partially by using z. B. borosilicate glass or Neutraglass or quartz glass should be avoided. However, such glasses have a significant disadvantage higher generation costs. It is also known to increase chemical resistance by that the surfaces of the finished glass objects with reheating to 400 to 600 ° C Exposure to alkali-binding, gaseous substances and / or vapors of volatile compounds suspends. The resulting increase in resistance is still for many purposes unsatisfactory.

According to the invention, an even greater chemical and mechanical resistance is achieved in that the objects during their manufacture at a temperature of 450 to 1000 ° C of the action of the gaseous Substances and / or vapors. It is preferable to treat with acidic gases such as sulfur dioxide, in combination with oxygen, e.g. B. atmospheric oxygen, or with sulfur trioxide or hydrogen chloride and / or with vapors of volatile compounds such as halides or carbonyls from Aluminum, zinc, zirconium, chromium, molybdenum, tungsten, cobalt, nickel, boron, manganese or silicon. A reduction in the alkali content also improves the electrical resistance themselves.

In order to achieve a permanent and complete effect, it is important that the whole Surface of the glass object in a uniform manner (or at least the entire outside or inside, when the increased chemical resistance is only required on one side, as in Bottles or tubes). It is essential that the whole glass be enclosed in a kind of skin which is completely or at least largely freed from alkali and / or stored, the cons-process to increase

chemical resistance

of glass objects

Applicant:

Fredrik Wilhelm Anton Kurz, Lidingö, and Robert Karl Ignaz Jagitsch,

Gothenburg (Sweden)

Representative: Dipl.-Ing. E. Prinz, patent attorney,
Münciien-Pasing, Bodenseestr. 3 a

Claimed priority:
Sweden from November 24, 1954 and November 17, 1955

Predrik Wilhelm Anton Kurz, Lidingö,

and Robert Karl Ignaz Jagitsch, Gothenburg (Sweden),

have been named as inventors

Contains glass components that increase stability. There must not be any areas on the surface that have not been treated, as this is where the attack can begin. This is all the more important as alkali is concentrated in the glass surface during the cooling of the glass objects, which was already indicated in studies in the thirties. The latest research has confirmed these assumptions; in fact, the glass surface usually contains almost twice as much Na ₂ O (at the expense of SiO ₂ ) as the deeper layers of the glass.

Therefore, if the treatment is to have any real effect, it must be uniform over the whole Surface. But this is only possible if the gases or vapors reacting with the glass are kept in motion, e.g. B. by blowing Or by means of fans, od by gas evolution. Like. So that actually the entire surface of the Glass or at least the entire inside or outside, if it is z. B. is packaging glass, comes into contact with the gas. This circulation of gases or vapors is essential as the one in question coming reactive gases and vapors are heavier than air and therefore otherwise to the ground would sink, making only the lower part of the glass objects in a more uniform and reliable manner Would be treated wisely, and since e.g. B. at

Σ09 640/215

Bottles try to keep warm air in the object, to prevent the penetration of reactive gases. Without the necessary, methodically carried out Circulation of the correct gases or vapors at the temperature just right for the reaction the effect is just random. In the best case, this is the inside or outside of the glass objects and, moreover, only incompletely and in the lowest part dealt with, while at the same time the danger exists that the salts precipitated on the glass surface burn into these parts of the glass.

In the treatment according to the invention, extremely small amounts of these substances are sufficient to the To give glass the desired surface resistance. On the other hand, a melting of oxides would of the basic materials mentioned in the glass mass require incomparably larger amounts in order to achieve the desired Effective, and very complicated, if not impossible to carry out. A vapor deposition according to the invention, however, can be carried out simply and cheaply.

The treatment is preferably carried out both with dealkalizing gases and with volatile substances, which form the resistance-increasing glass connections. The dealkalizing agent and the compounds mentioned can be added simultaneously or in any order be brought to action.

A combination of the treatment with gaseous dealkalizing agents and the supply of the Resistance-enhancing substances, such as aluminum chloride, results in a valuable combination effect. It has been shown that the The thin protective layer formed by vapor deposition of the metal compound adheres significantly more firmly to the glass surface is dealalized simultaneously or immediately thereafter or, if necessary, beforehand, as a result of which otherwise possible peeling of the protective layer is prevented.

The glass becomes further when the alkali removed by the action of the acid gases is replaced by other substances is replaced, which are fed at the same time, chemically and mechanically more resistant. this is especially true when the surface of the glass objects is heated at the same time, as below is explained in more detail.

The combination of an acidic gas with a volatile metal compound, e.g. B. aluminum chloride, results in a greater resistance not only against leaching of alkali, but also against leaching of silica, since the dealkalized residue, CaO · 6SiO ₂ , is less stable than z. B. an alumina glass formed instead, CaO · Al ₂ O _{3 · 6SiO 2} , is.

The effect of aluminum chloride embedded in a glass surface is twofold: Above all, the solubility of alumina glass is lower than that of a »residual glass« with a high silica and lime content and almost no alkali; In addition, such an alumina glass is chemically more resistant, since a stable glass can be obtained from mixtures of CaO-Al ₂ O ₃ -OSiO ₂ , while the mentioned residual glass is not stable as glass, but requires alkali in order to be able to be kept in glass form at all. By replacing water-sensitive alkali oxide glass with water-resistant aluminum oxide-lime-silica glass, the glass state is retained, which is not possible with lime-silica alone.

Another advantage is that a thin surface layer of e.g. B. alumina-containing glass offers better coloring options, which is of particular interest for glass fibers. The adhesive strength of organic dyes is gradually increased by the formation of a varnish between the metal oxide, e.g. B. Al ₂ O ₃ , and the organic dyes improved. Soda glass, on the other hand, has a strong tendency to be destroyed by hydrolysis on the surface,

ίο causing the paint to peel off.

It was also found that the treatment at a temperature between 500 and 1000 ° C and should preferably be carried out at decreasing temperature down to temperatures at which there is no need to fear any further diffusion of alkali oxide to the surface of the glass if the action of the gas occurs has already stopped. The treatment temperature is therefore between the temperature at the formed salt layers no longer on the glass

ao stick, but can be washed off or dried afterwards, and the lowest temperature, in which alkali can no longer diffuse to the surface from deeper layers. For alkali-lime-silica glasses is the interval between

a ₅ 800 and 900 ° C on one side and 400 to 450 ° C on the other. The dealkalization should preferably be carried out at a decreasing temperature in the range from 600 to 500.degree. If sulfur dioxide (with air), hydrogen chloride or the like.

act on your glass object under these conditions, a very thin layer is created on the glass surface that is free or almost free of alkali. By treatment with e.g. B. Sohwefeldioxid in the presence of air, the content of Na ₂ O in the surface layer can be reduced to a minimum under the conditions mentioned.

When it comes to treatment with volatile substances, resilience enhancers either Acting alone or in combination with a dealkalization, higher temperatures can occur come into question. In certain cases, it can therefore be useful or even necessary to apply the surface treatment at temperatures significantly higher than 600 ° C, e.g. B. in the treatment of glass fibers, to be carried out at which the production speed is so great that one is sufficient Great surface treatment is only achieved when the fabrics on the glass threads are already at the nozzles act directly where the temperature is above

1000 ° C. Due to the high speed, there is no danger here despite the high temperature for baking through the dealkalization treatment formed alkali salts.

In addition, it has been found that it is possible to convert the thin converted surface layer deepen when the treatment is carried out so that when the temperature of the glass object to be finished has dropped to a maximum of about 450 ° C, only the surface of this temperature is heated to about 600 ° C, and that in connection with this short-term surface heating the reactive gases or vapors act, after which the usual cooling under continued Gas exposure is made. If the inside of the glass is not heated, alkali cannot diffuse more to the surfaces, and this treatment gives a greater depth of the alkali-free or low-alkali skin.

This short-term and therefore only superficial heating of glass objects, which affects medium-

5 6

high temperatures happen, for example, amount to harmful crystallization phenomena wise so that the glass can lead during cooling when on the glass surface. The amount per the temperature has dropped to a maximum of around 450 ° C. The surface unit should correspond to what is required is, that is, a temperature at which the migration becomes necessary to remove the alkali on the surface Alkali ions to the surface has ceased to be the 5 or it by aluminum oxide plus a certain effect of gas heated to about 600 ° C, e.g. B. excess to compensate for the losses in the by blowing in. To replace treatment. The amount should be as low as

It is advantageous to keep the reactive substances as possible, otherwise the last stage of the shaping that is burnt in is fed. Oxyd coatings can have the opposite effect, for example when pulling window glass or io. The exact amount in a given case of glass tubes the treatment will be carried out, if this is expedient, determined by preliminary tests.
Window glass from the tub or the glass tube from The supply of reactive substances can through

the nozzle begins to be pulled. When the substance is produced, it is introduced in solid form, in solution of glass wool or glass fibers can be reactive or in vapor form.

Capable substances are supplied when the glass wool 15. The supply in solid form can be thrown out by supplying or the glass fiber or the nozzle powders, lozenges or the like, which are evaporated, leaves. When blowing bottles or incandescent lamps. The preferred combination of the action pistons, the gas in the last stage of the blowing action of volatile metal compounds and the introduction, expediently by mixing the action of acidic substances takes place in the simplest way in the blowing air. Other examples are the manufacture by making use of a preparation that consists of ampoules, where the sealing treatment is done, by fusing together aluminum chloride, and the production of glass blocks, where the handling and ammonium chloride is made. While each of them hung when the block halves were welded together, these chlorides sublimated when heated, ie can follow. Sometimes it may be more expedient to pass the vapor form without melting when the objects are exposed to the action of the reactive 25 a mixture of both at temperatures between capable gases during cooling 150 and 300 ° C depending on the composition of the melt, just when the mixture suitable for treatment. The main advantage of this combi-temperature is passed, so z. B. in the case of the harvested preparation consists in the fact that it is significantly less sensitive to the generation of air by glass insulators, encapsulated glass, and glass moisture than aluminum panels, glass mosaic or even glazed counter-minium chloride alone. Only through the application stand like glazed ceramic tiles. The combined preparation here is therefore possible, the application possibilities mentioned are only to dose aluminum chloride and to play pastilles, and the process can of course press most of them.
P> types of generation of glass can be adapted. The substances can be dissolved in suitable solutions

It is often expedient to introduce the means of generation, the drop-by-drop feeding or cooling process, when they are fed and evaporated for the. Examples of suitable solvents suitable for the action of the reactive gases are carbon disulfide or a temperature zone is passed through which glass versus nitrobenzene. When using, for example, a solution of aluminum chloride in carbon disulfide to be introduced into a closed envelope or the glass objects with such a solution, the following reactions occur on the glass surface: enter into which the gaseous substance then rings- soda-lime-silica- Glass + CS ₂ + O ₂ - + de-

bubbles or is introduced in some other way or where the _alkalized residue + Na ₂ SO ₄ + CO ₂ ,
Material brought to the gasification and _k in movement overall _NatrQn _ _{Ka]. K} j ^ acid- _gla | _{+ A1} q _ ^ _lime .

will hold, _ so that he will with all parts of the glass- _clay . _{Glass + NaC} l.
objects come into contact. This wrapping 45

is expedient precisely at the point of the her- Investigations have shown that the first

position, where the glass objects called reaction have already received their final shape to a greater or lesser depth and can have the effect, while the other reaction atmosphere, a temperature of 450 to 600 ° C, is essentially limited to the glass surface. or higher, if no deformation occurs. The reactive substances can also enter. The gaseous substance can then be sucked off in vapor form either as a mixture or as each and optionally fed back. The order gas will be introduced for itself. In this case, a cover cannot only guarantee that the automatic regulation of the dosage will not be volatilized by the acting gases, but rather that the use of the vapor pressure of the substances in question prevents the temperature from being easily achieved, especially for bottles and containers,
Containers with a large opening, the cold and therefore heavier air falls into the bottles under the action of certain volatile substances, the gases in particular Al Cl ₃ , it is important that this drives out anhydrous and the glass surface cools down so much that it is has shown that water-containing Al Cl ₃ and any gases that may still be present no longer have a weaker effect because the aluminum can react with the glass. In addition, the um- 60 is chloride hydrolyzed and aluminum hydroxide cladding is also advantageous, so that it does not react like aluminum chloride due to the circulation with glass.
for an even treatment of the entire surface, even if the best effect is to be provided on the surface area. treatment by the combined action of a

As already stated, in order to achieve the de-alkalizing agent and the desired resistance The result is that only small amounts of the reactivity-increasing compounds are achieved capable substances required. It is, however, often sufficient if only the final alkalization meaning that the dosage of the supplied, medium or uses the compounds mentioned reactive substances is precisely controlled because to be, especially when the stress at the small amounts do not produce the desired resistance practical application too large, d. H. bring improvement, while a too large 70 if the glass objects are not heated or the

Claims (4)

Exposure to acids or the like. It is then enough z. B. with an introduction of alumina through the action of aluminum chloride or with a dealkalization through, for example, sulfur dioxide, if the treatment conditions are otherwise maintained. The dealkalization treatment results in the formation of alkali sulfate, alkali chloride or the like on the surface of the glass. In most cases, these substances can easily be removed. In such cases, e.g. B. in the case of glass wool, where this cannot be done so easily, the salt formed can remain on the glass oil surface without any disadvantage. The treatment according to the invention is not only limited to glass objects in the actual sense, but can also be carried out on enamelled or glazed objects, since enamels and glazes are equivalent to glass in terms of their composition. Pa τ i: n τ \ xsiMi cc in · :. 1. Process for increasing the chemical resistance of glass objects Alkali-lime-silica glass as well as glazed and enamelled objects by acting of gaseous substances and / or of vapors of volatile compounds on the surfaces, thereby characterized in that the articles are kept at a temperature of 450 to 1000 ° C are exposed to the effects of these substances. 2. The method according to claim 1, characterized in that that the objects with acid gases, such as sulfur dioxide, in combination with oxygen, z. B. atmospheric oxygen, or with sulfur trioxide or hydrogen chloride and / or with Vapors of volatile compounds such as halides or carbonyls of aluminum, zinc, Zirconium, chromium, molybdenum, tungsten. Treated with cobalt, nickel, boron, manganese or silicon will. 3. The method according to claim 1 or 2, characterized in that the treatment is carried out will that. when the glass has cooled down to a maximum of about 450 ° C, only its surface again is heated to about 600 ° C, with the simultaneous supply of reactive gases or steaming, after which the final cooling begins. 4. The method according to any one of claims 1 to 3, characterized in that the glass objects during the generation or cooling process when passing through the for the action the reactive gases at a suitable temperature interval in a closed envelope are introduced into which the gaseous substances or vapors are introduced. Considered publications:
German patent specification No. 512 904. © 809 540/215 9.