JPH022832B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an ink for ceramics and glass, and more particularly to a yellow to red ink for ceramics and glass with good heat resistance that uses a cadmium sulfide pigment as a coloring agent. .

(Prior art) Conventionally, one way to print on ceramics and glass products is to print on the surface of ceramics and glass products using ceramic and glass ink consisting of low melting point frits and pigments. A method of baking at a temperature of 700℃ is used. As pigments for such inks for ceramics and glass, pigments having high heat resistance are required, and therefore various inorganic pigments are usually used.

(Problem to be solved by the invention) Among the above inorganic pigments, among the yellow to red pigments, cadmium sulfide pigments are widely used as pigments for inks for ceramics and glass because they have excellent various performances. However, when a low-melting frit containing lead oxide is used as a frit, this lead oxide and cadmium sulfide pigment react at high temperatures during baking, often resulting in unclear color tones. Therefore, baking is performed in a nitrogen atmosphere. It is necessary to carry out the process at a lower temperature, or to contain a large amount of Cd in the frit in advance.

Therefore, it is possible to use an inexpensive, low-melting-point frit containing lead oxide in a normal atmosphere without using such high-temperature equipment and complicated condition settings, and without using an expensive and special Cd-containing frit. However, there is a need for the development of cadmium sulfide pigments that do not change color during baking.

As a result of intensive research in response to the above-mentioned needs of the prior art, the inventor of the present invention has developed a method that produces low melting point frits even under normal atmosphere by applying a specific treatment to cadmium sulfide pigments for ceramic and glass inks. The present invention was completed based on the finding that a cadmium sulfide pigment that does not cause discoloration can be obtained.

(Means for Solving the Problems) That is, the present invention provides an ink for ceramics and glass comprising a low melting point frit and a pigment, wherein the pigment is a cadmium sulfide pigment having a silica coating on the particle surface.・It is an ink for glass.

To explain the present invention in more detail, the cadmium sulfide pigment having a silica film used in the present invention and which mainly characterizes the present invention can be obtained by any conventionally known technique, but a particularly preferred method is , a cadmium sulfide pigment is uniformly dispersed in water or a dilute silicate aqueous solution, and while the dispersion is uniformly stirred, a silicate aqueous solution and a suitable neutralizing agent, that is, an acid, are simultaneously gradually added into the dispersion. In this method, a silica film is deposited and formed on the surface of cadmium sulfide pigment particles.

To disperse the cadmium sulfide pigment in water or an aqueous silicate solution, any conventional pigment dispersion method can be used, and for example, a dispersing machine such as a sand mill using glass beads as a medium can be used.

The dispersion concentration of the cadmium sulfide pigment is not particularly limited, but in consideration of economic efficiency and product uniformity, it is preferably about 5 to 15% by weight.

In the case of the preferred method described above, the dispersion was heated to 80°C.
The above is preferably heated to about 85 to 90°C, and mixed with about 1 to 6% by weight silicate aqueous solution while stirring.
Best results are obtained by slowly adding 0.5 to 3% by weight of the acid separately and simultaneously and adjusting the pH of the mixture to a range of about 9 to 9.5. The addition time of the silicate aqueous solution and the acid aqueous solution varies depending on the production scale, but if it is too short, the uniformity of the silica film will be insufficient, and if it is too long, it is not economical, so it is generally A range of about 1 to 5 hours is preferred.

After adding the silicate aqueous solution and acid aqueous solution,
Adjust the pH of the dispersion to neutral and age it for an appropriate amount of time.
Then, by filtering, washing with water, and drying, a cadmium sulfide pigment having a silica film is obtained.

The acid used as a neutralizing agent may be any organic or inorganic acid, but the most preferable one is
0.5-3% by weight sulfuric acid.

The main feature of the ink for ceramics and glass of the present invention is that it uses a cadmium sulfide pigment having a silica coating as described above, and other components such as low melting point frit and vehicle are all conventionally known. It can be used as is.

For example, low melting point frits are mainly composed of lead oxide and other materials such as alumina, silica, calcium oxide, titanium oxide, sodium oxide, potassium oxide, zirconium oxide, zinc oxide, boron oxide, etc. It is preferable to adjust the molar ratio of the melting point to about 550°C to 620°C. All such low melting point frits are readily available on the market.

As the vehicle, squeegee oil, which is conventionally used in inks for ceramics and glass, is preferably used.

The ink for ceramics and glass of the present invention has the above three components as essential components, but any other conventionally known additives such as various inorganic pigments can be used in combination as necessary.

The cadmium sulfide pigment having a silica coating obtained by the above-mentioned preferred method or other methods preferably has a silica content of 2 to 10% by weight, and less than about 2% by weight. The heat discoloration resistance of the resulting cadmium sulfide pigment is insufficient, and if the amount exceeds about 10% by weight, the coloring power, hiding power, and other pigment properties of the resulting cadmium sulfide pigment decrease, so it is preferable. do not have.

As the cadmium sulfide pigment used in the above method, any conventionally known cadmium sulfide pigment can be used, such as a yellow cadmium sulfide pigment that may contain up to about 15% by weight of zinc sulfide, or an appropriate amount of zinc sulfide. Any orange to red cadmium sulfide pigment containing cadmium selenide (~50% by weight) can be used. Of course, it may also contain a small amount of extender pigment such as barium sulfate.

In addition, the silicate used in the present invention is
Any conventionally known water-soluble silicates can be used, and in addition to silicates, silicates containing small amounts of zirconates, titanates, and other metal salts may also be used. In the present invention, the most preferred is an alkali metal silicate, particularly No. 3 sodium silicate.

In the ink for ceramics and glass of the present invention,
The cadmium sulfide pigment having a silica coating is preferably used in an amount of about 4 to 8% by weight in the ink, and the low melting point frit is used in an amount of about 60 to 70% by weight in the ink. It is preferred that the vehicle is approximately
It is preferably used in a proportion of 25 to 30% by weight.

The ink for ceramics and glass of the present invention can be produced by a conventionally known method, for example, by sufficiently mixing, grinding, and kneading the composition using a three-roll machine or the like.

(Function/Effect) The ink for ceramics and glass of the present invention as described above is useful as an ink for imparting patterns such as various letters and figures to the surfaces of various ceramics, glassware, and enamel products. Ink for ceramics and glass is silk screen printed with any pattern using various other curved surface printing techniques, and this is baked at a temperature of about 500 to 700 degrees Celsius to produce a yellow to red color with a variety of fastness properties. Excellent patterns can be added.

The greatest feature of the ink for ceramics and glass of the present invention is that, in conventional inks for ceramics and glass that use cadmium sulfide pigments as a coloring component, the baking process is carried out in a substantially oxygen-free atmosphere such as a nitrogen atmosphere. Unless the cadmium sulfide pigment is used, or unless an expensive special frit containing a large amount of Cd is used, the cadmium sulfide pigment used will react with a portion of the lead oxide in the low melting point frit, causing the cadmium sulfide pigment to lose its sharpness. In contrast, the ink for ceramics and glass of the present invention does not require the use of such a complicated and costly nitrogen atmosphere or special frit, and can be printed with high colors. The cadmium sulfide pigment in the ink does not change color even if it is baked in an atmospheric atmosphere using the same inexpensive frit as in the past, and a pattern with high clarity can be produced.

Therefore, by using the ink for ceramics and glass of the present invention, excellent colored ceramics, colored glassware, colored enamel products, etc. can be provided at low cost with simple equipment.

Next, the present invention will be explained in more detail with reference to Examples. Note that % in the text is based on weight.

Example 1 Cadmium sulfide red pigment (CdS60%
Thoroughly disperse 200 g of CdSe40%) in 2 liters of water, heat it to 85°C, and while keeping it at this temperature, add No. 3 sodium silicate (Na2O/SiO
= 1/3, 30% aqueous solution) 34 g was diluted with 400 c.c. of water, and 7.8 cc of sulfuric acid (concentrated sulfuric acid/water = 1/2) was added to water.
400c.c. and the diluted aqueous solution were slowly added at the same time over a period of 3 hours, during which time the pH of the slurry was
Adjust to 9.2 to 9.5.

After dropping, the slurry is aged for 1 hour in this state, and then the pH of the slurry is adjusted to 7 with dilute sulfuric acid to complete the silica coating. The mixture was then filtered, washed with water, and dried in a conventional manner to obtain 210 g of a cadmium sulfide pigment having a silica coating. The silica film in this pigment accounted for 5% by weight of the pigment.

Example 2 Yellow cadmium sulfide pigment (CdS96%, ZnS 4%) was used instead of the cadmium sulfide pigment in Example 1.
A yellow cadmium sulfide pigment having a silica coating (5% by weight) was obtained in the same manner as in Example 1.

Example 3 0.5 g of cadmium sulfide pigment having a silica coating obtained in Examples 1 and 2, and 5 g of low melting point frit
and 2 g of squeegee oil were mixed and dispersed using three ceramic rolls to obtain inks A (Example 1) and B (Example 2) for ceramics and glass of the present invention.
On the other hand, comparative ceramic and glass inks A' (pigment corresponding to Example 1) and B' (pigment corresponding to Example 1) were prepared in the same manner using cadmium sulfide pigments without silica coating corresponding to Examples 1 and 2, respectively. A pigment corresponding to Example 2) was obtained.

Inks A and B for ceramics and glass of the present invention described above
and ceramic/glass ink A′ for comparison.
When B' was screen printed on a glass container and then baked in the air at 620°C for 20 minutes, the inks using inks A and B for ceramics and glass of the present invention showed clear color development, but compared to In both ceramic and glass inks A' and B', the color tone was darkened and the clarity was poor.

Claims (1)

[Claims] 1. Ceramics and pigments made of low melting point frits and pigments.
An ink for ceramics and glass, characterized in that the pigment is a cadmium sulfide pigment having a silica coating on the particle surface. 2 The amount of silica coating is 2 in the whole silica coating pigment.
The ink for ceramics and glass according to claim 1, which accounts for ~10% by weight. 3. The ink for ceramics and glass according to claim 1, wherein the low melting point frit is a lead oxide based low melting point frit.