KR19980702384A - Method of producing a protective coating layer on the surface of glass or ceramic products - Google Patents

Abstract

The present invention relates to a process for producing a protective coating layer on the surface of a glass or ceramic article, said coating layer having improved resistance to corrosive cleaning treatments. In carrying out the process of the invention, it comprises a pyrolytic precursor (in evaporated form) of tin oxide (SnO ₂ ) and a pyrolytic precursor (in evaporated form) of silicon oxide (SiO ₂ ) (for the latter So that the stream of oxygenous tint gas containing water vapor in an amount of from 0.6 to 3.0) and additionally at least 1 mol per 100 moles of tint gas deposits a mixed oxide protective coating layer of tin oxide and silicon oxide, It uniformly hits the surface of the article having a temperature above the decomposition temperature of the precursor and at least 550 ° C., and the deposition is continued until a coating thickness of 240-1,500 kPa is obtained.

Description

Method of producing a protective coating layer on the surface of glass or ceramic products

It is known to treat the surface of glass articles to improve their wear resistance. For example, US-A-4 144 362 describes coating glass bottles with thin films of tin oxide. The tin oxide coating layer is obtained by exposing the glass surface to the organic tin compound while heating at a temperature of 450 ° C. to 600 ° C. in the form of an oxygenous atmosphere such as air or finely divided. The tin compound decomposes and oxidizes in contact with the hot glass surface to form a tin oxide coating layer. The coating technique described and exemplified in US-A-4 144 362 results in a tin oxide coating layer having a thickness on the order of 45-120 mm 3.

According to US-A-4 130 673, after cooling a tin oxide surface-coated product to a temperature of 350 ° C. or lower, a thin layer of natural wax or synthetic polymer can be used as described above for tin oxide surface coatings. Apply to the tip. The combination of the two coating layers is described as reducing the scratches and cracks of the glassware during processing and processing.

The tendency to use glass containers, such as glass bottles, repeatedly is increased. Before the containers can be refilled, they are subjected to a strong cleaning treatment, for example using a caustic solution. After 5 to 15 wash cycles at 80 ° C. using 1-4% caustic solution, the tin oxide coating layer prepared as described above is completely removed. First, after several wash cycles, the thick portion of the tin oxide coating layer exhibits an unacceptable strong blue color. During repeated washing cycles the coating shows gray spots and finally disappears.

EP-A-0 485646 is intended for the production of rechargeable glass bottles provided with a metal oxide coating which withstands 8 hours of treatment with a 4% caustic solution at 80 ° C. The coating consists of tin oxide and titanium oxide and has a thickness of 400 to 1,000 mm 3. The coating is made by contacting a tin compound such as tin tetrachloride or dimethyl tin dichloride or a titanium compound such as titanium tetrachloride with a glass bottle having an external surface temperature of 550 to 700 ° C.

Thicker tin oxide coating layers made according to EP-A-0 485 646 provide better protection against corrosive cleaning than thinner coating layers known from the above US patents. However, the tests conducted by the present invention show that these thick coatings make the bottles less desirable to last longer for repeated use after 2-6 hours of cleaning (using 4% caustic solution at 80 ° C.) and are somewhat cloudy. . Considering the titanium oxide coating layer, it can be observed that the titanium starting compound is difficult to handle, difficult and ineffective for use.

WO 93/13393 shows a method of coating a glass by chemical vapor deposition (CVD) using a composition consisting of a tin oxide precursor, a silicon oxide precursor and a catalyst, preferably triethyl phosphite. The composition is deposited at a rate greater than about 350 mW / sec to form a coating layer having a thickness of 2,000 to 4,930 mm 3 according to an embodiment. The coating layer thus obtained can be combined with other layers to produce products having specific properties such as controlled release, refractive index, wear resistance or appearance. The clear glass bottle in Example 7 is coated with a vapor mixture consisting of tin oxide precursor, silicon oxide precursor and catalyst, triethyl phosphite and hot air, with a molar ratio of tin oxide precursor to silicon oxide precursor of 0.2. The vapor mixture was deposited for 10 seconds at an estimated deposition rate of about 200 mW / sec to produce a magenta-blue colored film having a thickness of about 2,000 mW. The deposition rate without triethyl phosphite is about 50 mW / sec.

The present invention provides a method for producing a protective coating layer for glass or ceramic products, the coating layer has a high resistance to corrosive cleaning treatment.

The method of the present invention also provides an improved coating layer for the glass container, which remains clean and substantially unchanged when the glass container is subjected to the corrosive cleaning process several times in preparation for its next use.

According to another object of the invention, a wax coating layer is applied on top of the protective coating layer and makes the glass or ceramic article more resistant to scratching.

The present invention also provides a simple, effective and reliable improved method for producing an improved protective coating layer on the surface of a glass or ceramic article, wherein a pyrolytic precursor that is easy to handle is used.

The present invention relates to surface coated glass or ceramic articles, in particular glass containers such as bottles, which are intended for repeated use after being washed with a caustic solution.

In the method for producing a protective coating layer on the surface of a glass or ceramic product according to the present invention, a thermally decomposable precursor of tin oxide (SnO ₂ ) (present in evaporated form) and a thermally decomposable precursor of silicon oxide (SiO ₂ ) (evaporation) And a stream of oxygenated tin gas containing water vapor in an amount of at least 1 mole per 100 mol of tin gas, and the tin oxide and silicon oxide When depositing a mixed oxide protective coating layer is made to uniformly hit the surface of the product having a temperature of at least 550 ℃ above the decomposition temperature of the precursor, when the deposition is obtained coating thickness of 240 to 1500 Pa Continue until.

CTU (Coating Layer Thickness Unit) is a unit used in the glass industry to define the coating thickness and is based on the reflection measurement of incident light. For the oxide coating layer according to the invention the thickness of 1 CTU can be estimated to correspond to about 3 kPa. For practical reasons used in the art, CTU thickness units will generally be employed through the following description and examples.

When the protective coating layer prepared according to the present invention is compared with known coating layers having the same CTU thickness, the coating layer of the present invention exhibits significantly improved resistance to corrosive cleaning treatments while maintaining a clean appearance. Proven outstanding properties, such as good resistance to, for example, 50 to 8 to 10 and more cleaning cycles, also make the coating layer of the invention very suitable for protecting ceramic products such as ceramics. In addition, excellent scratch resistance is obtained after applying a general wax coating layer to the tip of the coating layer of the present invention.

Possible explanations for the superior properties of the protective coating layer produced according to the invention are that the silicon oxide made during the coating and the contained silicon oxide contained in the at least partially coated substrate are melted together at the adhesive side, and / or Corrosion infringement can occur where hybrid-presence can occur, resulting in a harder coating or film with almost no gaps, and / or physical presence of hybrid-presence of silicon oxide in contact or cleaning tools such as knives. It is to increase the resistance of the coating layer to impact. In recent years, the mechanisms causing improvement have not yet been understood, and therefore the possible explanations described above should only be considered hypotheses and not limited thereto.

The present method for producing a protective coating layer consisting of tin oxide and silicon oxide is preferably carried out in the hot finishing process of a process line for producing a glass or ceramic product while the precursor to which the surface of the product is intended to decompose is sufficiently heated. In addition, a surface temperature of at least 550 ° C. is required to produce a coating layer having the required superior properties. The preparation of the coating layer by decomposition and oxidation of the precursor can be carried out by means of CVD (chemical vapor deposition) consisting of contacting the hot surface to be coated to result in the precursor in vapor form.

According to the CVD method, the precursor is applied from a stream of leach gas (usually air) that strikes the surface to be coated and contains the precursor in evaporated form. For short deposition times, for example less than about 10 seconds, the deposition rate is proportional to the deposition time. However, if a long deposition time is applied, the surface temperature will decrease and consequently the deposition rate and the efficiency of the coating method will be significantly reduced. Therefore, depending on the desired coating thickness, it may be necessary to start the coating at a rather high surface temperature or to provide additional heat to the surface to be coated during the coating itself. The somewhat higher temperature of the surface to be coated is also advantageous for other reasons, as discussed below.

The tin compound used as a precursor according to the present invention may be any tin compound thermally degradable at the temperature of the glass or ceramic article surface to be coated. The deposition of tin oxide occurs during the decomposition reaction with oxygen in the leach gas. Suitable pyrolytic tin compounds include monoalkyl tin trichlorides such as monomethyl tin trichloride and monobutyl tin trichloride, dialkyl tin dichlorides such as monoalkyl tin tribromide, dimethyl tin dichloride, dialkyl tin dibromide, and tin tetra Can be selected from chlorides. Monobutyl tin trichloride is most preferred for use as a precursor of tin oxide because it is easy to handle and very effective to use.

Silicon compounds used as precursors can also be thermally decomposed and silicon oxides can be prepared as described above taking into account tin compounds. Suitable silicone compounds are those of the formula R _n SiX _(4-n) where R is alkyl, alkenyl, alkynyl or an alkoxy group having 1 to 5 carbon atoms, or a phenyl group; X is a halogen atom or a hydroxyl group: and n is 0 To numbers 4 to 4). Tetramethoxy silane, tetraethoxy silane and tetra propoxysilane are examples of suitable silane compounds.

The tin compound is preferably present in an amount of 0.5 x 10 ^-4-2 x 10 ^-2 moles per mole of immersion gas. The molar ratio of tin compound to silicon compound is chosen between 0.6 and 3.0 in view of the desired high corrosive cleaning resistance. It has been demonstrated that the best results are obtained when the molar ratio is at most 2.0 and preferably at most 1.5 within the indicated ranges. It is further essential that the immersion gas, preferably as described above, contain water vapor in an amount of 1 to 50 moles per 100 moles of immersion gas. Sufficient amounts of water vapor are generally contained in the air used as an oxygen quenching gas when the protective coating layer of the present invention is prepared by atmospheric CVD according to a preferred embodiment. It is clear that the immersion gas is present at a temperature at which the precursor is present in evaporated form. In general, the temperature of the immersion gas is 100 ℃ to 210 ℃ and the preferred temperature range is 120 ℃ to 180 ℃. The velocity of the gas stream containing the above-mentioned components that hit the surface to be coated is generally selected within the range of 1 to 10 m / s and most preferably 3 to 5 m / s.

Although the temperature of the glass or ceramic surface to be coated is above the decomposition temperature of the precursor used, it is clearly necessary to be below the softening temperature of the coated product. In general, the protective coating layer is applied, for example, at the high temperature finish of the process line of glass bottles. It has been found that rather high temperature coated surfaces not only increase the deposition rate as described above but also substantially improve the resistance of the coated surface, particularly to corrosive cleaning. Therefore, the product surface temperature should be at least 550 ° C., the preferred temperature is at least 570 ° C. and the most preferred temperature at least 600 ° C., in particular 600 ° C. to 650 ° C. during coating. Additional heat may be provided to the product during the coating layer process to maintain the desired high surface temperature. Any suitable means for providing additional heat is conventional means such as pyrotechnics and the like.

The coating process is continued until the desired coating thickness is obtained. Indeed, in combination with a molar ratio of tin compound to silicone compound and a sufficiently high coating temperature as described above, the coating thickness provides excellent resistance to corrosive cleaning while the coating gives a clean appearance. According to the invention the thickness of the protective coating layer should be at least 80 CTU. If the temperature of the surface to be coated is provided sufficiently high at a thickness of at least 150 CTU and preferably at least 180 CTU, the coating layer does not show any blurring or undesired color and undergoes a strong washing treatment for 12 hours with 4% corrosive solution at 80 ° C. It was found to endure. Preferably the coating thickness is 150 CTU (450 kPa) to 900 kPa.

Hereinafter, the present invention will be described in more detail with reference to Examples.

In the following examples given only by the method described, the compounds of tin and silicon are applied to the hot air stream by means of an injector to evaporate these compounds. The temperature of the air is about 150 ° C. The gas mixture, as is well known, is directed to the surface of the glass article to be treated by means of a tube. In the following examples the inlet of the tube is 15 x 35 mm. 50 ml vials are treated to at least 2/3 of the height. They are heated in the oven to the desired temperature. The temperature is measured by a thermocell placed inside the bottle. The bottles are fixed by any suitable means, for example rod means for intercepting the bottles they wish to treat, and rotated during exposure in the process gas stream. The temperature of the glass at the start of the coating layer formation is measured by means of a set of far infrared thermometers (type CHINO IR-AHOT / -50 ° C. to + 1000 ° C.) calibrated with an emission capability of 0.93, sensing above a wavelength in the range of 4 to 13 μm. .

Scratch resistance measurement test

Two equally treated bottles were placed in the horizontal position, one at the tip of the other and pressed against each other while causing them to slip. When the pressure increased, the moment of scratching was clearly the moment when the bottles needed to increase the force applied to continue sliding with each other. The force applied was limited to 450 N above the force that led to the breaking of one or two bottles. Bottles with a suitable coating layer survived a force of 450 N without scratching.

Resistance measurement test for cleaning with corrosive solutions

The test conditions match those of gas station bottles.

The bottle was immersed in 4% sodium hydroxide solution maintained at 80 ° C. During testing, the vessel containing the corrosive solution must be flushed with nitrogen to avoid the conversion of sodium hydroxide to sodium carbonate as a result of the presence of carbon dioxide in the presence of surrounding air. For the same reason freshly prepared sodium hydroxide solution for each test was used to make sodium carbonate less damaging to the coating layer. A 150 mm 2 liter borosilicate glass jar was used for the test. This container can hold four bottles. The bottles were placed on a plate placed 20 mm from the bottom of the vessel. Each bottle was held by three pins 6 mm in diameter and 15 mm in length, which were held in holes in the plate. The plate has one hole in the center of 30 mm diameter and eight holes of 15 mm diameter along its circumference. The caustic solution was agitated at 500 rpm speed by a magnetic steering hot plate using a 40 mm long, 10 mm diameter steer. The thickness of the coating layer is American Glass Research Co. It measured using the apparatus of (AGR). Commonly used in the glassmaking industry, the device measures the reflections of treated glass surfaces, which are converted into coating thickness units (CTUs). As described above, 1 CTU obtained by the CVD method corresponded to about 3 kPa as the tin oxide / silicon oxide mixed coating layer according to the present invention.

The following non-limiting examples illustrate the invention.

Examples 1 and 2 are comparative examples.

In Example 1 the bottles were painted with a tin oxide coating layer and a wax coating layer according to the teachings of US Pat. No. 4,130,673.

The bottles in Example 2 were treated by providing a thicker tin oxide coating. To avoid unacceptable blurring, these coatings were made using higher tin oxide concentrations and higher tint gas rates.

Example 1 (Comparative Example)

A tin oxide coating layer was deposited on four bottles using precursors starting from monobutyl tin trichloride as described above. At the conclusion of this, a gas mixture consisting of air as tint gas, tin oxide at a rate of 1.5 x 10 ^-4 per mole of air, and water vapor at a 2.3 mole concentration per 100 moles of air, hits the surface of the glass bottle resulting in a temperature of 600 ° C. did. The speed of air was 3 m / sec. The deposition took place within 2.5 seconds. A tin oxide coating layer having a thickness of about 35 CTU was obtained. Two of these bottles were treated with wax coating through grinding of an aqueous suspension of poly (ethylene oxide) according to the process described in US Pat. No. 4.130,673. These two bottles showed scratch resistance of 450 Newtons. The coated bottles, as described in each of the following examples, showed the same excellent resistance to scratching after wax coating in the same manner. The other two bottles were subjected to several cleaning tests in 4% caustic solution at 80 ° C. The tin oxide coating layer was much damaged after 15 minutes of washing and completely removed after 30 minutes of washing.

Example 2 (Comparative Example)

The general coating procedure described in Example 1 was used including a temperature of 600 ° C. at the vial surface. The tin oxide coating layer having a thickness of 100 CTU, 150 CTU and 200 CTU starts from a gas mixture containing monobutyl tin trichloride at a ratio of 1 x 10 ^-3 moles per mole of air and water vapor at 2.3 moles per 100 moles of air. Formed. The velocity of the air was 5 m / sec. The deposition intervals were 3 seconds, 4.5 seconds and 6 seconds, respectively. The coating layer thickness was greater than the coating layer thickness of Example 1. After an hour of washing under the conditions of Example 1 all tin oxide was damaged and partially removed.

Example 3

The general coating layer procedure described in Example 1 was used including a temperature of 600 ° C. at the vial surface. In this example, bottles with two different coating layer thicknesses were prepared. The gas mixture used to form the coating layer on the bottle is monobutyl tin trichloride at 1 x 10 ^-3 mole ratio per mole of air, tetraethoxy silane at a 50 mole percent ratio of the mixture of two metal compounds, and 2.3 per 100 moles of air. It consisted of water vapor, the concentration of moles. The speed of air was 5 m / sec. The deposition intervals were 4.5 seconds and 6 seconds, respectively. The obtained coating layer had a thickness of 150 CTU and 200 CTU. They showed no blur. As for the resistance to washing with a corrosive solution as realized under the conditions of the above embodiment, after 12 hours of washing, the coating layer having a thickness of 150 CTU only showed a slight blur and the coating layer of 200 CTU showed no damage. .

Example 4

A coating layer was formed on the bottle as in Example 3, except that tetrapropoxy silane was used instead of tetraethoxy silane. Results similar to those in Example 3 were obtained.

Example 5

A 150 CTU thick coating layer was formed as described in Example 3. However, the water vapor concentration in the gas mixture used varied. The concentrations were 8 moles and 14 moles per 100 moles of air, respectively. All of the coatings obtained showed equally good resistance to caustic solution cleaning as the resistance of the 200 CTU coating of Example 3.

Example 6

The process was the same as in Example 3 except that tin tetrachloride or monobutyl tin trichloride was used instead of monobutyl tin oxide. In both cases, the same results as in Example 3 were obtained.

Example 7

The process was the same as in Example 3 except that different temperatures on the glass bottle surface were used (ie 575 ° C. and 625 ° C.). Since the deposition rates were almost the same at the high temperature, the deposition intervals were 150 CTU for the coating layer thickness of 4.5 seconds and 200 CTU for the coating layer thickness of 6 seconds. In the case of two coating layers, the resistance to washing with corrosive solutions was very satisfactory when the glass surface temperature was 575 ° C., and was excellent when the glass surface temperature was 625 ° C.

Example 8

The general coating layer procedure described in Example 3 with a temperature of 600 ° C. on the glass bottle surface was used. In this example, a coating layer having a thickness of 200 CTU was prepared, while various ratios of tin oxide to silicon compound were used to form the coating layer. Monobutyl tin trichloride was used at a rate of 1 x 10 ^-3 moles per mole of air. The concentration of tetraethoxy silanes varied. Water vapor was present at a molar ratio of tin oxide plus silicon compound of 11.5, which corresponds to 1.3 to 3.45 moles of water vapor per 100 moles of air. The coated layer was left to rinse for 6 hours with a caustic solution as described in the previous example. The tin compound / silicon compound ratio and the results of the wash test are given in Table 1 below.

Molar Ratio Tin Compound / Silicon Compound Cleaning test 0.5 (comparative) Very blurry; coating layer badly damaged 0.6 Slightly blurred 0.9 No blur (= very clean) 1.2 Slightly blurred 1.5 Slightly blurred 3.4 (Comparative Example) Blurry; coating layer damaged 10.1 (Comparative Example) Very blurry; coating layer badly damaged

Since no haze is the most desirable result and a little hazy is a satisfactory result, it will be evident that the molar ratio of tin compound to silicon is preferably selected within the range of 0.6 to 1.5.

Claims (14)

Pyrolytic precursor (in evaporated form) of tin oxide (SnO ₂ ) and pyrolytic precursor (in evaporated form) of silicon oxide (SiO ₂ ) (the former molar ratio of the latter to 0.6) And further wherein the stream of oxygenous tint gas containing water vapor in an amount of at least 1 mol per 100 moles of tint gas deposits a mixed oxide protective coating layer of tin oxide and silicon oxide and is at least 550 in decomposition temperature of the precursor. A method of producing a protective coating layer on a surface of a glass or ceramic article, which hits the surface of the article with a temperature of < RTI ID = 0.0 > C < / RTI > uniformly and continues until the deposition is achieved with a coating thickness of 240-1,500 Pa. The method of claim 1 wherein the molar ratio of the precursor of tin oxide to the precursor of silicon oxide is at most 2.0. The method of claim 2 wherein the molar ratio of the precursor of tin oxide to the precursor of silicon oxide is at most 1.5. The process according to any one of claims 1 to 3, wherein the immersion gas contains 0.5 x 10 ^-4 to 2 x 10 ^-2 moles of precursor of tin oxide per mole of immersion gas. 5. The process according to claim 1, wherein the tinted gas has a temperature of 100 ° C. to 210 ° C., preferably 120 ° C. to 180 ° C. 6. The method of claim 1, wherein the gas stream impinges at a rate of 1-10 m / s to coat the product surface. 7. The method of claim 1, wherein the temperature of the surface to be coated is maintained at a value of at least 570 ° C. during the coating process. The method of claim 7, wherein the temperature of the surface to be coated is maintained at a value of at least 600 ° C. during the coating process. The thermally degradable precursor of tin oxide is selected from monoalkyl tin trichloride, monoalkyl tin tribromide, dialkyl tin dichloride, dialkyl tin dibromide and tin tetrachloride. How is it done. 10. The process of claim 9, wherein the pyrolytic precursor of tin oxide is selected from monomethyl tin trichloride, monobutyl tin trichloride and dimethyl tin dichloride. The method according to any one of claims 1 to 10, Pyrolytic precursors of silicone compounds are of the formula R _n SiX _(4-n) where R is alkyl, alkenyl, alkynyl or an alkoxy group having 1 to 5 carbon atoms, or a phenyl group; X is a halogen atom or a hydroxyl group: and n is a number having from 0 to 4). The method according to claim 1, wherein the deposition is continued until a coating thickness of 450 kPa to 900 kPa is obtained. 13. The method according to any one of claims 1 to 12, wherein the deposition is carried out by atmospheric pressure CVD using air as the soak gas. 14. A method according to any one of the preceding claims, wherein said protective coating layer is produced on the outer surface of a glass container or porcelain for repeated use.