JPS61117132A - Frit for transparent porcelain enamel - Google Patents

Abstract

PURPOSE:To enable calcination of a frit at low temp. by forming a compsn. cong. a specified proportion of SiO2, B2O3, Na2O, K2O, Li2O, TiO2, etc. CONSTITUTION:A frit for transparent porcelain enamel consists of, by wt%, 30-50 SiO2, 5-25 B2O3, 10-30 Na2O+K2O+Li2O, 5-25 Na2O, 0-10 K2O, 1-5 Li2O, 5-15 TiO2, 1-10P2O5, 2-7 F, 0.5-10 BaO, 0-7 ZrO2+Sb2O3+ SnO2+ZnO+MgO+SrO+CaO+Al2O3, 0-3 MoO3. The frit is calcined at low temp. as low as 650-750 deg.C and provides same degree of resistance to hot water, acid, and alkali as conventional porcelain enamel frit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a transparent frit that does not contain lead components and can be fired at low temperatures.

(Prior art) Transparent enamel frit, which has been conventionally used for enameling iron plates, has the disadvantage that the firing temperature is as high as 800 to 850°C, which tends to cause thermal deformation of the iron substrate and reduce dimensional accuracy. However, low-temperature firing products that were developed to solve these drawbacks contained lead components, which caused problems in terms of environmental equipment and waste disposal. In addition, some products are known that do not contain lead components and can be fired at low temperatures, but they generally require long firing times and cannot be fired in the same amount of time as regular enamel frits. there were.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems and
It was developed for the purpose of producing a transparent enamel frit, which can be fired at a low temperature in the temperature range of about °C, does not contain lead, and can be fired in the same amount of time as regular enamel frit.

(Means for Solving the Problems) The present invention has a weight ratio of SiO230 to 50%, B2O33 to
25%, Na, O+ KzO+ Lizo 10-30
%, NatO5~25%, K, OO~10%, Li2O
1-5%, TiO25-15%, pzos 1-t.

%, F2~7%, Ba0O, 5~10%, ZrO, +S
b, 03+SnO, +ZnO+MgO+SrO+CaO
+AIZO: l O ~ 7%, Mo O: + 0 ~ 3%
It is characterized by consisting of.

In these compositions, Sin is a main glass-forming oxide that has a large effect on the coefficient of thermal expansion, softening point, and water resistance, but in the present invention, S is used to lower the melting point.
iO□ was set to 50% or less, which is lower than that of general enamel frit. Reduction of SiO The range is appropriate. B t O
Similarly to S i Oz, 3 is a glass-forming oxide, and is a necessary component for preventing devitrification and lowering the melting point. However, when B z O3 exceeds 25%, hot water resistance and acid resistance tend to deteriorate, and conversely, when it is less than 5%, it is not possible to sufficiently lower the melting point, making it impossible to achieve the desired low-temperature firing. Therefore, 5 to 25% is appropriate. Na
2O , K 2O , L i 2O alkali oxides are also important components for lowering the melting point, and must be contained in an amount of at least 10%. However, if the total amount of alkali oxide exceeds 30%, weather resistance deteriorates, so 10 to 30% is appropriate. If Nago in these alkali oxides exceeds 5%, it contributes to lowering the melting point, but if it exceeds 25%, it causes deterioration of acid resistance and hot water resistance, so 5 to 25% is appropriate. If K2O exceeds 10%, acid resistance and hot water resistance will deteriorate, so 10% or less is suitable. Li and O are very effective in lowering the melting point, but if the content is less than 1%, the effect is small, and if it exceeds 5%, the weather resistance deteriorates, so 1 to 5% is appropriate. TiO
2 improves hot water resistance and acid resistance, and 5
If it is less than 15%, the effect will not be produced, and if it exceeds 15%, it will become opalescent and transparency will not be obtained, so 5 to 15% is suitable. P and os are easily soluble and effective in lowering the melting point, and furthermore, they are components for obtaining a frit that can be fired at a low temperature and is difficult to burn out because the viscosity decreases little at high temperatures. These effects occur at a concentration of 1% or more.
10% is appropriate. F is a melting agent, and if it is less than 2%, lowering the melting point will be insufficient, and if it exceeds 7%, the string and weather resistance will deteriorate, so 2 to 7% is appropriate. BaO is a component that increases gloss, and if it is less than 0.5%, this effect will not occur.
If it exceeds 10%, weather resistance deteriorates, so 0.5 to 10%.
is appropriate. Zr0t, 5bzOs, 5nOz
, ZnO1Mg01SrO, , CaO1AI, O, these components are mainly used to improve chemical resistance, and one or several kinds are added as necessary, but the total amount of these components is 7%. If it exceeds, weather resistance deteriorates, so 0 to 7% is appropriate. MOO3 is a component that improves acid resistance. However, if it exceeds 3%, foreign crystals will occur on the surface, so a range of 0 to 3% is appropriate. Other pigments include Coo, NiOlNlol, CubSFezO:+
, Cr0z can be added up to 5% without damaging the basic composition.

(Example) Next, examples of the present invention will be shown together with comparative examples.

Transparent frit with the composition shown in Table 1, frit 10
0 parts (parts by weight, same below), 5 parts of clay, 0 potassium chloride
．． 2 parts pigment, 5 parts pigment, and 45 parts water.
The obtained pickpocket knob was glazed onto a 100 x 100 x 0.8 m steel plate with a lower glaze fired to a thickness of about 100 μm. After drying, it was held at 720° C. for 2 minutes and fired, and the chemical resistance, acid resistance, alkali resistance, and hot water resistance of each test piece obtained were measured. The results are shown in Table 2.

The measurement method is as follows.

(1) Citric acid spot test According to the regulations of JIS R-4301, three sheets of 30×30 fl filter paper are stacked on top of the test piece, 10% citric acid is added dropwise to the test piece, left for 15 minutes, and immediately washed with water to examine changes in gloss.

(2) Hot water resistance A 100 x 100 w test piece is brought into contact with pure water and boiled for 48 hours, and the weight loss is measured.

(3) Acid resistance 100 x 100 tm test piece
Contact with 0% phosphoric acid and boil for 6 hours, and measure the weight loss.

(4) Alkali resistance A test piece of 100 mm diameter is brought into contact with a 5% sodium birophosphate solution and held at 90°C for 6 hours, after which the weight loss is measured.

(Effects of the Invention) As is clear from the above description of the embodiments, the present invention enables firing at a low temperature range of 650 to 750"C without containing lead components, and is also capable of firing at a low temperature of 650 to 750"C compared to the conventional 800"C. ~85
Hot water resistance and acid resistance equivalent to or higher than those fired at 0℃,
In addition to having alkali resistance, it can be fired for a shorter time than conventional transparent frits for low-temperature firing. Therefore, even relatively thin substrates can be enameled without thermal deformation, and can be applied not only to forged steel plates and aluminized steel plates, but also to aluminum plates, glass plates, etc. Therefore, the conventional transparent material can greatly contribute to the development of industry as it solves the problems of the opaque frit.

Claims (1)

[Claims] SiO_230-50%, B_2O_35-2 in weight ratio
5%, Na_2O+K_2O+Li_2O10-30%
, Na_2O5-25%, K_2O0-10%, Li_
2O1-5%, TiO_25-15%, P_2O_51
~10%, F2~7%, BaO0.5~10%, ZrO
_2+Sb_2O_3+SnO_2+ZnO+MgO+
SrO+CaO+Al_2O_30-7%, MoO_3
A transparent enamel frit for low temperature firing characterized by comprising 0 to 3%.