JPS623776B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a low-melting-point opalescent glass composition for coating, which can be baked at low temperatures on substrates that deform or lose strength at high temperatures, such as glass, slate plates, and calcium silicate plates. Conventionally, as a glass composition for coating,
For example, enamel frits for iron plates and general low melting point frits are known. However, these have various drawbacks. That is, enamel frit for iron plates generally has a high firing temperature (800 to 850°C), with the lowest firing temperature being about 750°C. Therefore, it could not be applied to thin iron plates. This is because such substrates undergo thermal deformation at the enameling firing temperature. In addition, due to the high temperature firing, a large amount of hydrogen gas generated by the reaction between iron and water is absorbed by the iron plate, which is also a cause of the tendency for pimples to occur. On the other hand, general low-melting point frits are toxic because they contain lead, cadmium, etc., and have the disadvantage that they are difficult to dispose of even though they are discarded during the manufacturing process. In addition to the above, general sealing glasses are also known, but they are also expensive because they contain toxic substances and use expensive metals such as thallium and silver. This invention was made in view of these circumstances, and the composition, excluding water, contains 98 mol% or more of P ₂ O ₅ : 2 to 20 mol % SiO ₂ : 3 to 25 mol % Al ₂ O ₃ : 14 to 25 mol% _B2O3 : 10 to 40 mol% RO: 5 to 25 mol% _R2O : 12 to 24 mol% [However, RO is at least one of CaO, ZnO, BaO, and MgO _. It consists of CaO and CaO≧3 mol% R ₂ O consists of at least one of Li ₂ O, Na ₂ O and K ₂ O. ] SnO ₂ ,
At least one of TiO ₂ and ZrO ₂ is 1.0 to 15.0
mol [however, SnO ₂ :0 to 10.0 mol], and some of the above oxides (SnO ₂ , TiO ₂ and ZrO ₂ are also included in the oxides) are F ₂
The gist thereof is a low melting point opalescent glass composition in which fluoride is substituted in an amount of 3 to 15 moles per 100 moles of mother glass. That is, the low melting point opalescent glass composition configured in this manner can be fired onto a substrate at a low temperature, is non-toxic, and is inexpensive. Next, the reason why the composition is limited as described above in this invention will be explained. That is, P ₂ O ₅ is a component that lowers the melting point, and as the content of P 2 O 5 increases, the melting point of the composition is lowered, and when the composition contains Li ₂ O, the composition is baked. The acid resistance of the glass film formed by this is also improved. However, if P ₂ O ₅ exceeds 20 mol %, crystallization will become significant and vitrification will not occur. On the other hand, 2 mol%
If it is less than that, the effect of use will not be exhibited. SiO is a component that improves the alkali resistance of the glass film formed by baking the glass composition, and its increase improves the alkali resistance of the glass film. In particular, when the SiO ₂ content is 3 mol % or more, the alkali resistance becomes comparable to that of commercially available enamel. However, SiO ₂ tends to raise the softening temperature, and when it exceeds 25 mol %, the softening temperature becomes approximately 500°C or higher, making it unsuitable for low-temperature firing. Moreover, if SiO ₂ is less than 5 mol %, the effect of improving alkali resistance will not be exhibited. On the other hand, CaO is an ingredient that improves alkali resistance;
Since it tends to increase the thermal expansion coefficient of the resulting glass film compared to SiO ₂ , there are limits to its usage. Al ₂ O ₃ is a component that improves the acid resistance of the glass film formed by baking the glass composition,
This increase improves the acid resistance of the glass film.
In particular, when the Al ₂ O ₃ content is 18 mol % or more, it exhibits acid resistance comparable to commercially available enamel. However _{, Al2O3}
Similar to _SiO2 , SiO2 tends to gradually increase the softening temperature, and when it exceeds 25 mol%, the softening temperature becomes too high and it becomes unsuitable for low-temperature firing. vice versa,
When Al ₂ O ₃ is less than 14 mol%, the effect of improving acid resistance is no longer exhibited, and the glass film loses its luster. B ₂ O ₃ is a necessary component as a vitrification component, and acts to form a smooth glass film during baking. However, if B ₂ O ₃ is less than 10 mol %, vitrification will not occur, and if it exceeds 40 mol %, the surface performance of the glass film will deteriorate. RO is a component that improves the alkali resistance of the glass film formed by baking the glass composition, increases the coefficient of thermal expansion, and lowers the softening temperature of the glass composition. CaO, ZnO,
The respective effects of BaO and MgO are as follows. The effect of improving alkali resistance is CaO＞
The order is MgO＞ZnO≒BaO, and the effect of increasing the coefficient of thermal expansion is CaO≒BaO＞ZnO.
＞MgO, and the effect of lowering the softening temperature is ZnO≒BaO＞
The order is MgO>CaO. Furthermore, RO also improves the hot water resistance of the glass coating. However, if the RO content is less than 5 mol%, the above effects will not be exhibited, and conversely, if it exceeds 25 mol%, the coefficient of thermal expansion will become too large. Therefore, RO needs to be set within the range of 5 to 25 mol%. However, in this case, CaO is ZnO,
Even when used in combination with at least one of BaO and MgO, alkali resistance deteriorates unless it is 3 mol % or more. R ₂ O is a component that lowers the melting point, but at the same time increases the coefficient of thermal expansion. i.e. 12-18 mol% _R2O
, the coefficient of thermal expansion is 60 to 95×10 ^-7 /℃,
When it is 18 to 24 mol%, it is 90 to 110×10 ⁻⁷ /°C. Therefore, if R ₂ O is selected to be 18 to 24 mol %, the coefficient of thermal expansion will be close to that of the iron plate, making it optimal for coating iron plates. Also, R ₂ O
When 12 to 18 mol% is selected, the coefficient of thermal expansion becomes close to that of low-expansion coefficient substrates such as glass and slate plates, making it optimal for coating them. If R ₂ O is less than 12 mol %, the softening temperature will be too high, and if it exceeds 24 mol %, the thermal expansion coefficient will be too large, making it impossible to obtain the desired glass composition. SnO ₂ , TiO ₂ , and ZrO ₂ are all opacifying components, and are used alone or in combination. The opacification effect is exhibited when at least one of SnO ₂ , TiO ₂ and ZrO ₂ reaches 1 mol per 100 mol of the mother glass, and increases in proportion to the increase in the amount used. However, if the amount exceeds 15 moles, glass properties will be lost and the softening point and firing temperature will become high, making it impossible to obtain the desired glass composition. Among the opacifying components, particularly when SnO ₂ exceeds 10 moles, it rapidly crystallizes and loses its glassiness. Note that among these opacifying components, only SnO ₂ may be omitted in some cases. F derived from fluoride is a component that lowers the softening temperature, and _F2 is converted to 3% per 100 moles of mother glass.
It exhibits a remarkable effect in the range of ~15 mol, significantly lowering the softening temperature of the glass composition and making low-temperature firing possible. However, such effects
At less than 3 moles, it is hardly exerted, and at 5 moles, it starts to be noticeably exerted, and becomes almost constant at 10 moles. and
If the amount exceeds 15 mol, the acid resistance of the resulting glass film will decrease. Next, the raw materials for the low melting point opalescent glass composition of the present invention will be explained. The raw materials for the components constituting the glass composition of this invention include raw materials that produce oxides of the components or mixtures of these oxides when fired, or raw materials that convert part of the oxides of the components into fluorides when fired. Any raw material that produces fluorine may be used. For example, raw materials that produce oxides or mixtures of oxides by firing include silicic anhydride, aluminum silicate, sodium carbonate,
Sodium sulfate, sodium chloride, sodium silicate, boric acid, sodium borate, aluminum hydroxide, calcium carbonate, zinc carbonate, zinc biphosphate, magnesium carbonate, phosphoric acid, calcium phosphate, lithium borate, lithium carbonate, zinc white, Sodium nitrate, zinc hydroxide, ammonium phosphate, sodium phosphate (orthophosphate, condensed phosphate), zinc borate, tin oxide, zirconium oxide, titanium oxide, zirconium silicate, potassium carbonate, potassium silicate, Examples include barium carbonate, and raw materials that generate fluorine for converting some of the oxides into fluorides by firing include aluminum fluoride, quartzite, sodium fluoride, lithium fluoride, potassium fluoride, and firefly. Examples include stone, sodium silica, potassium silica, etc. Next, a method for producing the low melting point opalescent glass composition of the present invention will be explained. That is, the low melting point opalescent glass composition of the present invention is produced as follows. (b) Select appropriate raw materials from the above raw materials and thoroughly grind and mix them at room temperature, heating if necessary. Of course, the glass may be melted without pulverization and mixing. (b) The above mixture is heated and fired in a furnace to melt and vitrify it. (c) At the final stage of glass melting, 1
Allow to melt for ~4 hours. Stir in between if necessary. (d) In addition, when melting the glass, pre-firing may be performed if necessary. For example, when using phosphoric acid, sodium carbonate, boric acid, and zinc oxide, the raw materials are first thoroughly mixed and reacted at room temperature. At this time, heat if necessary. Next, the mixture is dehydrated while reacting at 150 to 500°C for 1 to 3 hours. In this way a solid is obtained. Next, crush it. Next, (c) glass melting is performed. This method is safe and convenient since almost no dehydration or decarbonization occurs during glass melting, and no boiling over from the inside of the crucible occurs. (e) In addition to the above, if raw materials containing water such as dibasic sodium phosphate, dibasic zinc phosphate, zinc carbonate, ammonium phosphate, etc., or carbonates or ammonium salts are used, before melting. Preferably, the above (d) pre-firing is performed. (F) Either throw the molten glass into water and let it cool quickly.
Pour onto a thick iron plate to cool. (g) The obtained glass is pulverized using a pot mill, vibratory mill, sieve machine, etc. In this way, the desired low melting point opalescent glass composition is obtained. Next, the case where a substrate is coated with the glass composition obtained in this manner will be described. That is, in the case of dry glazing, the glass composition is mixed with a pigment, and in the case of wet glazing, pigments, additives such as carboxymethylcellulose, gum arabic, etc. are added as necessary according to conventional methods, and the glass composition is made into a water-based slip and glazed. Then, if necessary, after drying, it is fired. The firing temperature varies depending on the glass composition, but a temperature approximately 150 to 200°C higher than the softening temperature is appropriate.
In these cases, operations other than those exemplified above, or other incidental operations or auxiliary operations may be included. For example, when coating a glass substrate, slow cooling should be used as a general rule, and the maximum temperature should be 530 to 650℃.
Consideration should be given to holding it for about 10 minutes.
Alternatively, a fluidized dipping method may be used for coating the frit powder. In this case, it is necessary to preheat the substrate to be coated to a temperature above the softening point of the frit, and it is also convenient to preheat the frit to a temperature slightly lower than the softening point. As described above, the low melting point opalescent glass composition of the present invention has a low firing temperature, so the firing cost is low, and it does not deform or reduce the strength of thin iron plates, glass, slate plates, calcium silicate plates, etc. at high temperatures. It can be printed on any substrate. Then, by baking, it is possible to form an opalescent glass film that is not only water resistant but also weather resistant, acid resistant, and alkali resistant. In addition, the low melting point opalescent glass composition of the present invention can approximate the coefficient of thermal expansion of the opalescent glass coating to that of a substrate such as a thin iron plate, so it is possible to improve the adhesion between the opalescent glass coating and the substrate. Further, according to the glass composition of the present invention, drawbacks that occur during high-temperature firing, such as
It can eliminate the occurrence of black flies and oxidized scale. Furthermore, since the glass composition of the present invention does not contain harmful or expensive substances, it does not cause problems such as toxicity and is inexpensive. Next, implementation will be explained. The raw materials were mixed as shown in Table 1. In Table 1 (Part 2), the raw material formulations in Table 1 (Part 1) have been changed to represent the mol% of oxides.

【table】

[Table] Next, the above raw material mixture was melted using an alumina crucible in an electric furnace set at 1200 to 1300°C. In this case, the raw material mixture for the glass composition was charged into the alumina crucible in two or three times. After all the raw material mixtures were added, the mixture was clarified for about 1 hour, then poured into water, rapidly cooled, and crushed in a pot mill to obtain a low melting point milky white glass composition. The physical properties of the obtained low melting point opalescent glass composition were as shown in Table 2.

[Table] The method for measuring the physical properties of the glass composition is as follows. (1) Coefficient of thermal expansion and softening temperature A rod-shaped glass composition with a diameter of about 3 mm was used as a sample, and its expansion was measured using a displacement meter at a heating rate of about 20° C./min. The softening temperature was determined from the recording paper at the point at which the glass changes from expansion to contraction due to deformation. (2) Boiling loss Adjust the particle size of the glass composition to 32 to 60 mesh, accurately weigh 3 g, put it in a 300 c.c. eggplant flask with 50 c.c. of hot water, and boil for 60 minutes while refluxing.
The boiled sample was filtered through a 1G3 glass filter, and the weight before and after boiling was measured to determine the loss in boiling, which was expressed as a percentage of the weight before boiling. (3) Acid resistance weight loss 2000 g of glass composition powder with a uniform particle size of 32 to 52 mesh was placed in a 100 c.c. beaker, and after stirring with 50 c.c. of 1N hydrochloric acid aqueous solution at room temperature using a stirrer for 15 minutes, The acid resistance weight loss was calculated by suction filtration using a 1G1 glass filter cm ² and weighing the residue. Acid resistance weight loss = (1-residue/2000) x 100(%) (4) Alkali resistance weight loss 2000g of glass composition powder with a uniform particle size of 32 mesh to 60 mesh was placed in a 100 c.c. beaker.
After stirring with a stirrer at room temperature for 15 minutes with 50c.c. of 1N-NaOH aqueous solution (30℃),
The alkali resistance weight loss was calculated by suctioning through a 1G1 glass filter and weighing the residue. Alkali resistance loss = (1-residue/2000) x 100(%) Next, a dispersant and water are added to the glass composition (powdered) obtained as described above to form a flip. It was coated on the substrates (glass plate, steel plate) shown in the table and fired under the conditions shown in the table to form a milky white glass film. The performance of this opalescent glass film is shown in the same table.

[Table] The performance test method in Table 3 is as follows. (1) Acid resistance 3cm x 3cm impregnated with 5% citric acid aqueous solution
Three pieces of corner paper were placed on top of the sample, covered with a watch glass, and left for 15 minutes, then the paper was removed, washed with water, and dried. And the degree of surface erosion is AA,
Evaluation was made on 5 scales: A, B, C, and D. AA is the best with the least degree of erosion, and D is the worst. (2) Alkali resistance Using a 10% aqueous sodium carbonate solution, operations and evaluations were performed in the same manner as for acid resistance. (3) Hot water resistance A 10 cm x 10 cm sample was immersed in boiling water for 5 hours, and changes in appearance were examined. (4) Weatherometer The condition was examined after testing for 300 hours. As shown in Table 1, in Examples 1 to 10, BaO-generating raw materials such as barium carbonate and K ₂ O-generating raw materials such as potassium carbonate were not used, but the above-mentioned raw materials were used. Example 1 even if
It has been confirmed that effects similar to ~10 can be obtained.

Claims (1)

[Claims] 1 Composition: P ₂ O ₅ : 2 to 20 mol % SiO ₂ : 3 to 25 mol % Al ₂ O ₃ : 14 to 25 mol % B ₂ O ₃ : 10 to 40 mol % RO: 5 to 25 mol% R ₂ O: 12 to 24 mol % [However, RO consists of at least CaO of CaO, ZnO, BaO and MgO, and CaO≧3 mol % R ₂ O is Li ₂ O, Consists of at least one of Na ₂ O and K ₂ O. ] SnO ₂ ,
At least one of TiO ₂ and ZrO ₂ is 1.0 to 15.0
mol [however, Sn ₂ O: 0 to 10.0 mol], and some of the above oxides (SnO ₂ , TiO ₂ and ZrO ₂ are also included in the oxides) are F ₂
A low melting point opalescent glass composition in which fluoride is substituted in an amount of 3 to 15 moles per 100 moles of mother glass. 2. The low melting point opalescent glass composition according to claim 1, wherein _2R2O is selected within the range of 18 to 24 mol%. 3. The low melting point opalescent glass composition according to claim 1, wherein _R2O is selected within the range of 12 to 18 mol%.