JPS5830254B2 - enamel frit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an enamel frit which has excellent acid resistance and hot water resistance, and which imparts good thermal shock resistance to the enamel.

Conventionally, enamel frits that had excellent hot water resistance and acid resistance generally contained a large amount of high-temperature melting components (for example, S i02 ) and a small amount of low-temperature melting components, resulting in poor workability and poor thermal shock resistance. .

In order to obtain an enamel frit with good hot water resistance, acid resistance, and thermal shock resistance, it was necessary to use a leaded frit containing lead, but adding a large amount of lead to the frit component is never desirable from a health and pollution standpoint. It's not a thing.

In the case of dry cast iron, unleaded enamel frit has excellent hot water resistance and acid resistance, but compared to leaded enamel frit, it is difficult to obtain a smooth glazed surface and the firing temperature is higher.

High firing temperatures cause deformation of the material and large distortions in the glaze layer due to cooling conditions, which can cause cracks and peeling of the glaze layer during the manufacturing process. Become.

Recently, JP-A-52-68223 has been proposed as a lead-free enamel flint with excellent acid resistance and hot water resistance, but the hot water resistance, especially the thermal shock resistance, is still insufficient.

On the other hand, lead-free and zircon-containing materials with fairly good hot water resistance and thermal shock resistance have been put into practical use, but their acid resistance is insufficient.

In view of this current situation, it is necessary to solve the above-mentioned drawbacks of lead-free frit and provide a frit that is suitable for use in steel plates or cast iron that has excellent acid resistance, hot water resistance, and good thermal shock resistance. As a result of various studies, we have completed the present invention.

The gist of the present invention is as follows (in the following, all terms "excellent" and "excellent" refer to weight φ).

That is, the frit composition of the present invention is L i 2QO, 5-4
%, and the total amount of either L120+Na20, 20 for Li20+, 20 for Li20+Na20+ is 10-25%, B2030-2.5ψ, Ti
021~26%, S+0230~64%, ZrO220
% or less, and the total amount of 5i02+TiO2+ZrO2 is 31-65%, Ba0 is 1-35%, and MgO is 4%.
Below φ, ZnO, CaO, SrO is below 20% BaO
+MgO+ZnO+CaO+SrO total amount is 10 to 3
It is characterized by being in the range of 5φ.

The frit of the present invention is characterized by the presence of an L + 20 component and low boric acid content.

Generally, for high B203 content frits L I 20
However, in the present invention, by suppressing the boric acid component to 2.5% or less, L t 2
The Q and B2O3 component range enhances the synergistic effect of the Li20 component and divalent alkali metal oxide, and significantly improves acid resistance and heat resistance, and this is precisely where the feature of the present invention lies. .

Next, the reasons for limiting the frit components of the present invention will be described.

The reason why Li2O is an essential component and its range is 0.5 to 4 is because it is necessary to improve acid resistance and hot water resistance. This is because it is necessary to enhance the synergistic effect of improving acid resistance and hot water resistance.Furthermore, the reason why the total amount of Li2O + Na2O% L120 + 201L12 + Na2O + 20 is set to 10 to 25% is that if it is less than 10%, the melting temperature will increase. This is because a high temperature is required when melting the frit, a high temperature is also required when firing the enamel, and it is difficult to make the enamel surface smooth.

On the other hand, if it exceeds 25%, acid resistance and hot water resistance will be significantly reduced.

The reason why the B2O3 component was set to O~2.5% is that B2O3 is 2.5%.
If it exceeds 5%, the synergistic effect with Li20 will be lost and acid resistance, hot water resistance, and thermal shock resistance will deteriorate.

The reason why the T102 component is set to be 1 to 26 is that if it is less than 1%, the acid resistance will decrease, and if it exceeds 26%, the coefficient of expansion resistance will increase and the thermal shock resistance will decrease.

Furthermore, the SiO2 content is set at 30 to 64% because if it is less than 30φ, both acid resistance and hot water resistance will be significantly reduced, and if it exceeds 64%, high temperature will be required to melt the frit, and the enamel surface of the final product will be smooth. This is because it becomes difficult.

The reason why the total amount of S j 02 + T i 02 + ZrO2 was set to 31 to 65 is because if the total amount is less than 31%, the acid resistance and hot water resistance will decrease significantly, and if it exceeds 65%, the flint will not come off. This is because it becomes poorly soluble or its thermal shock resistance is significantly reduced.

In addition, ZrQ2 should be within the above range and less than 20 in the relationship between S + 02 and T i02.

The reason why the BaQ content is 1 to 35% is that if it is less than 1%, a high temperature is required to melt the fried metal, and the acid resistance decreases.

Moreover, if the diameter exceeds 35φ, the enamel surface will lose its smoothness and the hot water resistance will also decrease.

Furthermore, BaO+M! The reason why the total amount of i'0 + Zno + caO + srO was set to 10 to 35% is related to thermal shock resistance.
If the total amount is less than io%, the thermal shock resistance and hot water resistance will decrease, and if it exceeds 35%, the frit will be difficult to melt, and crystal precipitation or loss of luster will occur during sintering.

Furthermore, the reason why M2O is set to 4% or less and ZnOCaO and SrO are each set to 20% or less is the same as the above-mentioned reason.

Although the essential object of the present invention is achieved by the above-mentioned component composition, if necessary, one or more of F2, 5b205 or P2O5 can be added in an amount of up to 10% without impairing the basic properties.

The frit of the present invention can be manufactured by a conventional method using conventional raw materials, and the waxing process can be performed by a conventional method.

In other words, when the steel plate is glazed, the frit is milled with clay and necessary additives, the resulting slip is glazed by dipping or spraying onto a steel plate that has been pretreated in the usual way, and after drying, it is fired. A so-called wet method is used.

On the other hand, cast iron is pretreated by sandblasting, and then, in addition to the above-mentioned wet processing method, the cast iron base is sprayed with a primer, heated to red, and then flint and additives such as pigments are added as necessary. In addition, a so-called dry method in which a powder is sprinkled and fired can also be employed.

The flint glaze of the present invention has excellent acid resistance, hot water resistance, and thermal shock resistance compared to conventional flint glazes.

In particular, cast iron dry glazes have excellent thermal shock resistance, which means that they are resistant to external forces such as tension and compression that occur between the glaze and the base material after firing.
This is a desired property.

Conventionally, frits with good acid resistance have had problems with this thermal shock resistance, and a major drawback has been that they tend to cause clutching and chimping.

In order to eliminate these drawbacks, cast iron bathtubs use two types of bathtubs with different coefficients of thermal expansion to prevent clutching and chipping on the rim and inner surface.
Normally, enamel processing was performed by applying glazes of a certain size or higher to the rim and the inner surface, but with the frit of the present invention, such separation is not necessary at all, and the enamel processing is performed using one type of glaze. Not only can it be processed, but it also has excellent hot water resistance and acid resistance.

As mentioned above, the frit wax of the present invention is
It has excellent properties never seen before in both the waxing process and usage.

The superiority of the frit of the present invention will be specifically illustrated below in comparison with comparative examples.

Comparative Example 1 Various raw materials were blended to give the compositions shown in (1) to (3) [satisfying the free throat composition range of the present invention] in Table 1, mixed, and then melted at 1200 to 1300°C. , quench to obtain frit.

Similarly, frits of conventional examples (1) to (3) in Table 1 are obtained.

Clay, necessary additives, and water were added to the six types of frits obtained, and the mixture was milled in a ball mill to form sled knobs.

The six types of slips mentioned above were fired on a 2wh thick 10 x 771 steel plate which had been pretreated in advance by a known method and had been baked with a base coat, and the enamel layer thickness after firing was 250 to 300 mm.
The glaze was spray-glazed to a black color, and after drying, it was fired at 840°C for 3 minutes.

The test piece thus obtained was tested twice for each slip.
Each sheet was subjected to acid resistance and hot water resistance tests.

The results of these tests are shown in Table 2.

Comparative Example 2 In order to examine the thermal shock resistance of the six types of frits obtained in Comparative Example 1, a cast iron plate with a thickness of 58 mm and 10 cm square was sprayed with a primer and fired at 950°C. Take it out and add 20 pieces of frit while it is still red hot.
Sprinkle dry-milled frit powder so that 15% or more remains on the sieve mesh (sieve opening 74 microns), and again
The test piece is fired for 60 to 90 seconds in a furnace at a temperature of 0.degree.

Separately, in order to compare acid resistance and hot water resistance in the case of dry cast iron glazes, two test pieces of the same frit were made using the same dry method as above using the steel plates used in Comparative Example 1.

The reason why a cast iron plate was not used here is due to the weighing range of the balance.

The results of these tests are shown in Table 3.

The methods of acid resistance, hot water resistance and thermal shock resistance tests in this comparative example will be briefly described.

Acid resistance test JISR-4301 7.3 Add 200 ml of citric acid aqueous solution of Section 6 in a vigorous method according to the mass loss acid resistance test method,
Heat the lower part of the test piece with an electric heater and keep it boiling for 2 hours 3
After a 0 minute hold, the weight loss of the wax layer is shown divided by the test surface area.

The measured value is the average value of two samples and is expressed as d/d.

Hot water resistance test After keeping ion-exchanged water in a boiling state for 100 hours continuously in the same equipment as the hot water resistance test, the weight loss value of the floating layer is divided by the test area.The measured value is the average value of two samples. m9/
Denoted as cyA.

Thermal shock resistance test The test piece is placed in a dryer at 150°C for 20 minutes, then taken out and immediately placed in water at room temperature (18-20°C). This operation is repeated until cracks appear in the sample.

After checking the state of cracks with red ink, the entire sample is immersed in a hot water bath, boiled for 24 hours, then placed back into room temperature water, and changes in the degree of cracks are examined with red ink.

This test is repeated for 20 days, and those with a significant increase in cracking are judged to have poor thermal shock resistance.

As is obvious from the above-mentioned Comparative Examples (1) and (2), the frit of the present invention has excellent properties that are completely different from conventional ones, whether applied to steel plates or cast iron.

Next, embodiments of the present invention will be specifically described.

Example 1 Various raw materials were blended to have the oxide composition shown in Table 4, mixed well, and then melted in a crucible at 1250°C.

Approximately 10 to 15 minutes after all the raw materials were melted, they were taken out and quenched in water to obtain frits 1 and 2.

The obtained frit 1 was milled using the following mill formulation to obtain a slip.

Frit 1 100 parts by weight Frog's eye clay 5 Potassium chloride 0.2 Water 45 The slip of Frit 1 was immersed, dried, and fired in a box-type electric furnace at 830° C. for 3.5 minutes to obtain a product.

The obtained product had a very good gloss, a transparent glaze layer with a smooth surface, and excellent acid resistance and corrosion resistance.

Example 2 Frit 2 obtained in Example 1 was pulverized to 15% 'A6' through a 200 mesh sieve using a dry mill to obtain a powder frit.

On the other hand, a cast iron bathtub was pretreated with sandblasting, and then a pre-preparation spray was applied to the fabric, which was heated to 900~1
After baking at ooo℃ for 6 to 8 minutes, take it out and sprinkle the above-mentioned powder frit evenly on the inside of the substrate and the flange part through a sieve vibrating with compressed air while keeping it red hot.
After heating for 60 to 90 seconds in a furnace at 00-1000℃, take it out and sprinkle powdered flint evenly over the entire surface of the bathtub.After heating it in a furnace at 900-1000℃ for 60 to 90 seconds, take it out and let it cool in the air. It was made into a product.

The obtained product had good emulsion, a glossy and smooth surface, and no pinholes.

It also had excellent acid resistance, corrosion resistance, and thermal shock resistance.

Example 3 Various raw materials were blended to have the oxide composition shown in Table 5, mixed well, and then melted at 1300 to 1350.
Frits 3 and 4 were obtained by rapid cooling.

The obtained flint 3 was mixed with the following mill to obtain a milk-squeezed slip.

Frit 3 100 parts by weight Frog's eye clay 5 〃 Potassium chloride 0.2〃 Water 45 〃 Pre-treat the slip in the usual way, apply the glaze by spraying on a flat plate with a baked base glaze, and box-shape at 850℃ for 3.5 minutes. When fired in an electric furnace, a smooth enameled surface with a glossy surface and excellent acid resistance was obtained.

Example 4 Frit 4 obtained in Example 3 was pulverized with a dry mill so that 80 mesh was passed through and IO% remained on a 200 mesh sieve.
A powder frit was obtained.

A cast iron flat plate with a thickness of 57111t11 Q Om Sprinkle the powder frit evenly through the sieve and heat it again in a 960°C oven for about 70 seconds, then take it out and sprinkle the powder frit evenly again.9
After heating at 60° C. for 1 minute and 30 seconds, it was taken out and allowed to cool in the air to obtain a product.

The resulting product had a glossy, smooth surface and excellent acid resistance and thermal shock resistance.

As shown in the comparative examples and examples above, the frit of the present invention has excellent properties that have not been available in the past.

Claims (1)

[Claims] I Li2O 0.5 to 4% by weight (hereinafter referred to as weight%), and L I 20 + N 220 % L l 20 +
K20%L l 20+Na2O+ and 20 total amount is 10-25%, B2030-2.5%, T
1021-26%, 5i0230-64%, Zr02
20% or less and the total amount of 5i02+TiO2+ZrO2 is 31-65%, Ba01-35%, MgO is 4% or less, ZnO, CaO, SrO is 20% or less and Ba is
The total amount of O+MgO+ZnO-t-CaO+SrO is 1
Enamel frit characterized by being in the range of 0 to 35%