JPS624334B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a low melting point opalescent glass composition for coating glass, thin iron plates, etc., which can be fired at low temperatures. Conventionally, as a glass composition for coating,
For example, hollow frits for iron plates and general low melting point frits are known. However, these have various drawbacks. That is, hollow frits for iron plates generally have 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 a substrate is thermally deformed at the enamel 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 is: SiO ₂ : 10-24 mol% Al ₂ O ₃ : 24-30 B ₂ O ₃ : 20-30 RO : 10-15 R ₂ O: 15-22 [However, RO + R ₂ O = 28-35 mol% RO consists of at least one oxide selected from the group consisting of CaO, ZnO, BaO, SrO and MgO, and R ₂ O It consists of at least one oxide selected from the group consisting of Li ₂ O, Na ₂ O and K ₂ O. ] 3 to 10 ZrO ₂ per 100 moles of mother glass consisting of
In addition to containing 5 moles or less of TiO ₂ , and some of the above oxides (ZrO ₂ and TiO ₂ are also included in the oxides), the mother glass is 100% in terms of F ₂ . The gist thereof is a low melting point opalescent glass composition in which fluoride is substituted in an amount of 2 to 15 moles per mole. That is, the glass composition thus constructed can be fired onto a substrate at low temperatures, 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,
If SiO ₂ is less than 10 mol % in the mother glass, boiling resistance, chemical resistance, especially alkalinity will deteriorate. Conversely, when SiO ₂ exceeds 24 mol%, the softening temperature increases and SiO 2 is an acid resistance imparting component.
Al ₂ O ₃ is relatively reduced and acid resistance deteriorates.
If Al ₂ O ₃ is less than 24 mol %, acid resistance will not be sufficiently improved, and if it exceeds 30 mol %, the softening temperature will increase. Moreover, when B ₂ O ₃ is less than 20 mol %, the softening temperature becomes high, and when it exceeds 30 mol %, boiling resistance and chemical resistance deteriorate. RO is a component that lowers the softening temperature and also improves the coefficient of thermal expansion.
When this content is less than 10 mol %, the softening temperature becomes too high, and when it exceeds 15 mol %, the coefficient of thermal expansion becomes too large, making it impossible to obtain the desired opalescent glass composition. R ₂ O is a component that lowers the softening temperature and also a component that increases the coefficient of thermal expansion. This one is 15
If it is less than mol%, the softening temperature will be too high and 22
If it exceeds mol%, the coefficient of thermal expansion becomes too large, making it impossible to obtain the desired opalescent glass composition. If the total amount of RO + R ₂ O is less than 28 mol %, the softening temperature will become too high, and if it exceeds 35 mol %, the thermal expansion coefficient will become too large, and the chemical resistance and boiling resistance will deteriorate. Furthermore, in RO+R ₂ O, as the amount of R ₂ O increases, although the softening temperature decreases, chemical resistance tends to deteriorate and the coefficient of thermal expansion tends to become too large. And in the RO component,
CaO is more effective in improving chemical resistance than other RO components, and ZnO is more effective in lowering softening temperature than other RO components. In addition, in the R ₂ O component, Li ₂ O, Na ₂ O, and K ₂ O have a softening temperature lowering effect and a chemical resistance improving effect in this order. _F2 derived from fluoride is a softening temperature lowering component, and is 2 to 15 mol per 100 mol of mother glass.
In particular, the maximum effect can be achieved by selecting around 10 moles. However, if too much is added, acid resistance will decrease. ZrO ₂ and TiO ₂ are each opacifying components, and both components effectively exhibit an opacifying effect together. When ZrO ₂ is less than 3 moles per 100 moles of mother glass, there is almost no opacification, and on the other hand, when it exceeds 10 moles, the softening temperature becomes too high. Also, _TiO2
If it exceeds 5 mol per 100 mol of mother glass, it will remain as a residue at the bottom of the crucible during glass melting. In addition, in the above explanation, the effects and reasons for limitations of the constituent components of the glass composition are explained individually, but in reality, since there are interactions between the constituent components, the composition of the glass composition can be uniquely determined. The composition of the glass composition described above was determined based on a comprehensive consideration that also took these into account. Next, the raw materials for the glass composition of this invention will be explained. The raw materials for the components constituting the glass composition of the present invention include raw materials that produce oxides of the components or mixtures of these oxides when fired, or raw materials that convert some of the oxides of the composition into fluorides when fired. Any raw material that produces fluorine may be used. For example, raw materials that produce oxides or mixtures of these oxides by calcination include anhydrous silicic acid, aluminum silicate, sodium sulfate, sodium silicate, sodium nitrate, sodium chloride, soda carbonate, calcium carbonate, calcium hydroxide, and sulfuric acid. Calcium, boric acid, sodium borate, aluminum hydroxide, alumina, magnesium carbonate, barium carbonate, strontium carbonate, zinc oxide, magnesium chloride, magnesium oxide, magnesium hydroxide, magnesium sulfate, strontium sulfate,
Compounds include strontium oxide, barium sulfate, barium hydroxide, zinc carbonate, titanium oxide, tin oxide, zirconium oxide, lithium carbonate, potassium carbonate, lithium hydroxide, potassium hydroxide, lithium chloride, and potassium chloride. Fluorides that generate fluorine for converting a portion of the oxide into fluoride include sodium fluoride, lithium fluoride, potassium fluoride, calcium fluoride, sodium silicate, and cryolite. Next, a method for manufacturing the glass composition of the present invention will be explained. That is, the glass composition is manufactured 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 soda carbonate and boric acid, the raw materials are first thoroughly mixed and reacted at room temperature. At this time, heat if necessary. next,
Dehydrate while reacting at 150-500°C for 1-3 hours. In this way a solid is obtained. Next, crush it. Next, (c) glass melting is performed.
In this way, dehydration and decarbonation hardly occur during glass melting, and therefore no boiling over from the inside of the crucible occurs, which is safe and convenient. (e) In addition to the above, when a material containing water, carbonate, or ammonium salt is used as a raw material, it is preferable to perform the pre-calcination described in (d) above before melting. (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, vibrating mill, Raikai machine, etc. In this way, the desired 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 on glass, slow cooling should be used as a general rule, and the maximum temperature should be 530-650℃ for 3 minutes or more.
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 glass composition of the present invention has a low firing temperature, so the firing cost is low, and the thermal expansion coefficient can be approximated to that of an iron plate and glass, so it has good adhesion. Furthermore, it has excellent water resistance. Further, according to the glass composition of the present invention, it is possible to solve the drawbacks that occur when firing at high temperatures, such as the formation of black spots and oxide 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, examples will be described. 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】

[Table] Next, the above raw material mixture was heated and dried at 150 to 200°C for 8 hours. Next, coarsely crush this,
Clarification was performed at 1000-1200°C for 70 minutes. The obtained glass composition was poured onto a thick iron plate, rapidly cooled, and then ground in a pot mill to form 100 meshes. The physical properties of the obtained glass composition were as shown in Table 2.

【table】

[Table] The method for measuring the physical properties of glass is as follows. (1) Coefficient of thermal expansion and softening temperature A glass bar with a diameter of approximately 3 mm was used as a sample, and the heating rate was approximately
Expansion was measured by a displacement meter at 20°C. 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 to 32 mesh ~ 60 mesh, accurately weigh 3 g, and add 50 g to a 300 c.c. eggplant flask.
Add cc of hot water and boil for 60 minutes while refluxing. The boiled sample was filtered through a 1G3 glass filter, and the weight loss before and after boiling was determined to determine the weight loss after boiling, which was expressed as a percentage of the weight before boiling. (3) Acid resistance weight loss Put 2000g of glass powder with a particle size of 32 mesh to 60 mesh into a 100 c.c. beaker,
After stirring with a stirrer for 15 minutes at room temperature with 50 c.c. of citric acid aqueous solution (30°C) of g/100 c.c., the acid resistance loss was calculated by suction filtration with a 1G1 filter and weighing the residue. Acid resistance weight loss = (1-residue/2000) x 100 (%) (4) Alkali resistance weight loss Put 2000g of glass powder with a particle size of 32 mesh to 60 mesh into a 100 c.c. beaker for 1N.
After stirring with a stirrer for 15 minutes at room temperature with 50 c.c. of NaOH aqueous solution (30°C), the alkali resistance weight loss was calculated by suction filtration with a 1G1 filter and weighing the residue. Alkali resistance weight loss = (1-residue/2000) x 100 (
%) Below, the results of coating a steel plate with these glasses of G-1 to G-15 and evaluating the opacity will be explained. (1) Preparation of glaze for coating (composition) Glass frit 100 parts by weight Particulate silicic acid 1.5 parts by weight Potassium chloride 0.5 parts by weight Water 50 parts by weight The following mixture was placed in a ball mill, mixed and pulverized for a certain period of time to produce a slurry-like glaze. create. The particle size of the glaze is controlled to be 1 to 2 g as a residue of 200 meshes per 50 g of slurry. (2) Glazing and firing of glaze The above slurry is applied to an enamel steel plate (size 10cm x 10cm) that has been pre-glazed and fired to a film thickness of 200mm.
It was coated to a thickness of μ to 250μ, and fired under the firing conditions shown in Table 3 to prepare a milky white enamel sample. (3) Measurement of opalescence The opalescence was also evaluated in terms of appearance and reflectance. The results are shown in Table 3. (4) Acid resistance test/alkali resistance test Based on the acid resistance test method and alkali resistance test method (JIS) for enamel. The results are shown in Table 3.

【table】

【table】

Claims (1)

[Claims] 1 Composition: SiO ₂ : 10-24 mol% Al ₂ O ₃ : 24-30 B ₂ O ₃ : 20-30 RO : 10-15 R ₂ O : 15-22 However, RO + R ₂ O = 28 to 35 mol% RO consists of at least one oxide selected from the group consisting of CaO, ZnO, BaO, SrO and MgO, and R ₂ O consists of Li ₂ O, Na ₂ O and K ₂ Consists of at least one oxide selected from the group consisting of O. ZrO ₂ is 3 to 10 per 100 moles of mother glass consisting of
In addition to containing 5 moles or less of TiO ₂ , and some of the above oxides (ZrO ₂ and TiO ₂ are also included in the oxides), 100 moles of mother glass in terms of F ₂ A low melting point opalescent glass composition in which fluoride is substituted in an amount of 2 to 15 moles per fluoride.