JPS60221341A - Iron enamel composition - Google Patents

Abstract

PURPOSE:To obtain the titled iron enamel composition without generating any defects at an early stage even in a low-softening point enamel frit from which a large amt. of alkali, etc. is eluted by incorporating water glass into an enamel frit for iron as an agent for preventing the tearing and cracking. CONSTITUTION:0.1-2pts.wt. water glass is added to 100pts.wt. enamel frit for iron as an agent for preventing the tearing and cracking. Moreover, since the pot life of the slip of a low-softening point enamel frit having the following composition can be prolonged by the water glass, a low-melting enamel having excellent color development with single application can be made to approach practical use. The above-mentioned low-softening point enamel frit is composed at least of SiO2, B2O3, Na2O3, Na2O, K2O, ZnO, and F2 and >=1 kind intermediate oxide selected from Al2O3, ZrO2, and TiO2, and contains 31-39%, by weight, SiO2, 13-21% B2O3, 14-22% Na2O, 1-5% K2O, 13-20% ZnO, and 2-10% F2.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a glaze composition for iron enamel.

Structure of conventional examples and their problems Generally, in the hollow treatment of iron plates, a hollow frit with a coefficient of thermal expansion slightly smaller than that of the iron plate, viscosity as a suspension agent, colloidal silica, and NaNO2゜N a A 1 as a stop adjustment agent are used.
02 or MgCO2 electrolyte and water as a solvent are mixed and milled, the resulting slip is pickled, glazed on a nickel-treated iron plate, and fired.

Among the defects that appear on the surface of the hollow layer processed in this way, tearing (
), cracks, hair lines, sponge foam, and conopr heads. These defects are caused by boron and alkaline components released from the hollow frit.

The extent of this depends on the slip manufacturing conditions and slip storage conditions.

Hollow film thickness, drying method, and handling of dried utensils.

It is influenced by firing conditions.

Among these defects, tearing, cracking, and hairlines occur relatively early. Tearing, cracking, etc. were prevented by adding a small amount of urea to the slip after milling.

However, the method of adding urea is a high temperature firing type (goor
There is no problem with Norinodo's slip, which elutes a relatively small amount of alkali, etc. (above 700C), but low-temperature baking, where a lot of alkali, etc. elute, is caused by the alkali, etc. eluted from the frit. Urea or urea decomposition products are adsorbed onto clay, colloidal silica, or bentonite particles in an accelerated manner, and the adsorbed urea or urea decomposition products are desorbed at high temperatures near the firing temperature, producing spongy bubbles on the hollow surface.

The present inventors have found that it is well suited to CdS-based red pigments and Tz 02-based pigments, and can freely develop color tones such as red, yellow, pink, green, blue, brown, black, and white. We have developed a frit with the following composition as a low softening point hollow frit. That is, at least 5102.
B2O3, Na2O, 20. ZnO and F2 and A
At least one intermediate oxide selected from the group of 12O3, ZrO2, TiO2, and 310231-39 weight ratio, B2Q313-21 weight ratio, Na 2014-22 weight ratio, and 201-5 weight ratio, Zn013~20% by weight y F2 2~10 weight ratio, [Al2O3] + [zro2] 10 [TlO2] = 2~
9 Weight candy Al2O3 weight type hollow frit with low softening point where Al2O3≦5.

However, when this frit is baked on an iron plate with a general hollow glaze composition as described below, the following problems occur.

Frit 100 parts by weight Frog-eye slime 4 parts by weight Colloidal silica 0.5 parts by weight Floor Plain O~0.3 parts by weight Na No 2 0 - 1 part by weight Pigment 6 parts by weight Water 47 parts by volume That is usually milled There is no problem if the slip is used for a short time after
If the slip is stored in water and does not contain urea, the hollow film made of slip after about 4 hours will show tearing, cracking, and
Hair lines appear and spongy foam appears after 10 days or more. In addition, when 0.3 parts by weight of urea is contained, approximately 6 parts by weight of urea is contained.
Sponge foam was generated after a period of time, and tearing or cracking occurred after 30 hours.

In general, low softening point hollow frits elute more alkalis, etc. than high temperature types. It is thought that this eluted component impairs the wetting (compatibility) between the glaze and the iron plate, or that the eluted component creates crystalline substances (for example, borax) between the frit particles, causing tearing and cracking.

In particular, the low softening point hollow frit of the above composition has excellent coloring properties, but has the drawbacks of eluting a large amount of alkali and reboron during slipping, and the drawbacks of high surface tension of the frit, which may cause tearing. Cracks were very likely to occur.

Therefore, we tried using urea as a glaze compound, but in low-temperature baking type enamels (hereinafter referred to as low-melting enamels), urea can be added not only during milling, but also after milling. There was a drawback that the temperature during milling and slip storage had to be controlled so that it did not become too high (approximately 2 Or or less).

Thus, a tearing and cracking preventive agent to replace urea has become necessary.

Purpose of the Invention The purpose of the present invention is to provide an iron hollow glaze composition in which defects do not occur early even in a low softening point hollow frit in which a large amount of alkali etc. is eluted. The glaze composition contains hollow frit for iron as a main component, and water glass is used as a tearing and crack preventing agent in an amount of 0.1 to 7 parts of hollow frit 100M.
The basic content is 2 parts by weight.

Furthermore, by extending the pot life of the slip of the low-softening point enameled 7')yt with the following composition by using water glass, it is possible to bring a low-melting enameled one-time application with excellent color development closer to practical use.

The composition of the low softening point hollow frit is at least S
102, B 203. Na20, K2O
, ZnO and F and Al2O3, ZrO2, TiO
810231-39 weight ratio, BO13-2
1f□%.

3 N a 2014-22% by weight, 201-6% by weight Z
nO 13-20% by weight, F2 2-10% by weight.

[Al2O3] + [Zro2] 10 [1102922-9
weight%.

Al2O3≦5wt% T Z r 02≦5wt%,
T 102≦6% by weight.

Water glass seems to act as a binder between the hollow frit particles and prevent tearing and cracking, but the mechanism is not clear.

If water glass is contained in an amount exceeding 2 parts by weight per 10 parts by weight of Holonlit, the working temperature will rise, bubbles will occur, the gloss will become dull, and burrs (cracks) will easily occur.0. If the amount is less than 1 part by weight, there will be little effect on preventing tearing and cracking, and if a frit is used in the summer where there is a large amount of alkali elution, especially when the persimmon glaze film thickness is thick (approximately 200 μm or more), tearing may occur. , cracks, and hair lines are likely to occur.

As for the method of adding water glass into the glaze composition, mill addition is preferable. However, even when using water glass, the milling time is short (within 1 hour) and the temperature in the mill is 30°C.
It is desirable not to exceed c.

First, make a hollow frit. To do this, raw materials for each component are mixed according to the desired frit composition. After thorough dry mixing, the mixture is heated and melted at a temperature of 1100 to 13001. Since the heating temperature for 9 hours changes the composition ratio of the final frit, it is necessary to carefully control the heating temperature. It is important to allow vitrification to proceed for 20 to 40 minutes after decomposition of the raw materials, and to stir as necessary. If the melting temperature is maintained for too long, the alkali components and F2 components will sublimate.
Try not to make it too long. After melting, the glass is placed in water and rapidly cooled. When this is dried, a hollow frit is obtained.

To 100 parts by weight of the hollow frit thus obtained, 3 to 9 parts by weight of viscosity, colloidal silica, etc. as a suspending agent, and sodium nitrite as a stopping agent.

Add up to 1 part by weight of magnesium carbonate, sodium aluminate, etc., and up to 10 parts by weight of pigment, and add 40 to 70 parts by volume of water to silica powder, hydrated borax, and grind with a ball mill or the like.
Mix.

At this time, 0.1 to 2 parts by weight of water glass is also added. Here, if the temperature inside the mill is controlled to be as low as 30C or less, the bot life of the slip after being taken out of the mill will be extended.

The particle size of the slip is 1 when the 200 mesh (74 μm) residue of the slip 50 at is applied by spraying.
~7jil', or 16y or less when glazing is done by dipping, and preferably as rough as possible to reduce elution of frit components.

The hollow glaze composition thus obtained is sprayed or dipped to give a solid glaze to steel utensils that have been pickled and subjected to electroless nickel plating, dried, and fired to form a hollow film. In addition, the firing conditions are, for example, 690C or higher for 4 minutes in the case of a low-melting hollow frit.

Description of examples Next, actual examples will be explained together with comparative examples.

Production of four low-melting hollow frits First, the raw materials shown in Table 1 below were blended in the proportions shown in the same table to prepare formulations 1 and 2 for low-melting hollow frits. Then, mix this mixture and put it in an aluminum pot, 1
After melting and clarifying at 10Q to 1300C,
It was poured into water and cooled.

As a result, the low-melting khorof in Table 2! J throat G1゜G-2
was gotten.

Margins below Table 1 Table 2 (Unit weight %) Hoo7rittu G-1. Both G-2 are low-temperature fired frits that can be fired at 750C or lower, but G-1 has less wettability between the frit and the iron plate and a larger amount of alkali elutes during slipping.

The evaluation method in Table 2 was as follows.

(1) Tablet test (fluidity of frit) The fluidity of glass frit is measured by taking a frit 2y with a particle size that passes through a 200-mesh sieve, placing the sample in a mold, and
It is press-molded under a load of tons to form a tablet with a diameter of 12.7M. Then, the sample was placed on a steel plate that had been pickled and treated with electroless nickel agate, and heated at 690C for 6 minutes.
Measure the flow diameter of the sample with a caliper. This value is an evaluation that combines the hardness and wettability of the frit.

(2) Dissolution amount of frit in hot water Soak 5 pieces of 7wt with a particle size that passes through a 200mesh sieve but not a 300mesh sieve in 100CG distilled water, boil it for 1 hour, and remove the supernatant liquid. The eluted alkali component was titrated with 0.1N-H2SO4 using a methyl olezi indicator, and the amount consumed was taken as a measure of the amount of eluted alkali.

(B) Production of hollow slip Low melting hollow frit G-1 obtained as above,
After drying and coarsely pulverizing G-2, mill additives shown in Table 3 below were blended in the proportions shown in the same table.

Next, apply the mixture shown in Table 3 for 9 minutes to 1oQ.
The mixture was placed in a pot mill and mixed and pulverized at about 75 r-ppm for 1 hour. At this time, the milling temperature is below 300, and the slip particle size (60CG 200 mesh residue) is 1~
The slip adjusted to 7y was checked for the condition of the hollow coating immediately after being taken out of the mill, and stored in a constant temperature bath or constant temperature water bath at the storage temperature shown in Table 3, and the condition of the hollow coating was checked periodically.

Margin below Hollow processing was performed under the following conditions.

Base material: size 100jllllx 100j1m, thickness 0, 61+/II(7)llpp material, pre-treatment is pickling weight loss value 400-6004/dm = Kkel adhesion amount 14
~20 ml/dyTh glaze; Spray method Hollow film thickness i 15C)-1BOpm Drying method; Far infrared drying firing conditions; Firing time: 3 minutes 40 seconds; firing temperature shown in Table 4.

Table 4 shows the results of checking the pot life under the above conditions.

The effect of water glass on Frit G-1 was compared with the case where no tearing/cracking inhibitor was added and the case where urea was added.

As shown in Comparative Example 1 in Table 4, when the slip is refrigerated, there is no practical problem even if no inhibitor is added.

Table 4 in the margin below However, when storing slips of G-1 Fritz at room temperature near 35C, for example in the summer, it is necessary to add a tear/crack preventive agent (Comparative Example 2). This will result in an unexpected slip.

Therefore, when we tried urea as an inhibitor (Comparative Example 6), 6
Sponge foam will form within hours. Therefore, these inhibitors are also impractical.

In comparison, adding 0.1 to 0.2 parts by weight of water glass (Leprosy Examples 1 to 5) delays the occurrence of tearing and cracking even when the slip is stored at around 35C, and also suppresses the formation of sponge foam. The generation is also much slower than with urea, etc., and in the summer, it is possible to obtain a product that can be used for 1 to 2 days without refrigeration.

Example 5. Comparative Examples 7 and 8 showed the pot life characteristics of Friso G-2 slip. As shown in Table 4, even low-melting hollow frits have good fluidity and a frit with a small amount of alkali leached out can be used for practical purposes without adding tearing or cracking inhibitors (comparison). Example 7). However, even in the case of Friso) G-2, it is necessary to add an inhibitor if tearing or cracking is likely to occur due to the impact of handling the utensil. In this case, as shown in Example 6, it is not practical unless water glass is used as the inhibitor.

Effects of the Invention As described above, the hollow glaze composition containing water glass of the present invention is less likely to generate tearing, cracking, and sponge bubbles.

In particular, when using a low-melting hollow frit that has poor fluidity and wettability with iron plates and has a large amount of alkali elution,
It is possible to provide a hollow glaze composition that can be sufficiently used even in summer. Conventional low-melt enameled hollows have many characteristics such as less deformation, less strength deterioration, less pinholes and less porosity, and are resource and energy efficient.
Since the elution of 2O3 and alkaline components is large, the pot life of the slip is short, which poses a major problem in practical use.

Claims (2)

[Claims] (1) An iron enameled glaze composition containing 0.1 to 2 parts by weight of water glass as a tearing and crack preventing agent per 100 parts by weight of enamelled for iron. (2) The hollow frit for iron is at least S 102
. B2O3, Na2O, 20. znO and F2 and A
12O3゜Zr02, at least one intermediate oxide selected from the group of T102, and S
31-39% by weight of iO2, 13-21% by weight of BO
, 14-22% by weight of N'a 20 3 , 1-5% by weight of N'a 20 , Zn
Contains 13 to 20% by weight of O and 2 to 10% by weight of F2,
The iron hollow glaze composition according to claim 1, which is a low softening point hollow frit containing the intermediate oxide/product in an amount of 5 weight units or less, and a total amount of 2 to 9 weight units.