JPS5927218B2 - self-cleaning coating layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-purifying coating layer formed on the wall surface of a self-purifying cooking device, and is intended to provide a coating layer having excellent catalytic activity, particularly against oxidation reactions.

The coating layer on the wall of this type of self-cleaning cooking device has conventionally been made of enamel using glass foam as a binder, or coated with silicate as a binder.

A typical example of the former is Special Publication No. 49-33088.
As shown in the above publication, there was a method in which a suitable oxidation catalyst was melt-blended into a vitreous matrix and the wadding D was permanently fixed to the entire enamel coating. or,
As described in Japanese Patent Publication No. 47-17832, a commercially available oxidation catalyst and a commercially available vitreous frit are mixed to synthesize a splint, and this spout is deposited on an enamel substrate formed on a metal substrate. There were some that had 9 pieces of paint sprayed on them. On the other hand, in the latter method, as disclosed in Japanese Patent Publication No. 49-28120, a catalyst is dispersed and supported on a metal substrate using an alkali 9-metal silicate as a binder. Although each of these partners has its advantages and disadvantages, in the case of the former using glass frit as a binder, during the manufacturing process,
Baking at 500°C to 850°C limits the type, shape, and thickness of the base material, or the surface area of the coating layer is limited unless the glassy foam is melted to some extent. The drawback was that the force was small and the catalytic effect was not exerted. Furthermore, in the latter case, in which an alkali metal silicate is used as a binder, the bonding force is weak, and there is a drawback that the bonding force is weak and the bonding force tends to peel off from the substrate due to mechanical impact.
A more serious problem was that silicates were soluble in water vapor. As described above, although self-cleaning cooking devices are commercially available, they have been unsatisfactory due to problems in manufacturing costs, catalytic performance, and quality.

The present invention solves the above-mentioned conventional drawbacks, and uses the binder of the self-cleaning coating layer with the general formula MO・XP2O,・YH,O
(However, M is At, Mg or Calx, y is a real number)
It is characterized by being a phosphate represented by

Examples include primary aluminum phosphate, secondary aluminum phosphate, tertiary aluminum phosphate, and magnesium phosphate. The curing mechanism of phosphate is that when heated, it becomes a polymeric condensed phosphate as shown below. When this condensed phosphate is heated to a higher temperature, it crystallizes,
harden.

For example, when primary aluminum phosphate is heated, it crystallizes and hardens through the following reaction. 1UUU ~ In this reaction, when the heating temperature is below 500℃,
Dehydrated At2O3・3p,05 trigram and At2O
3.Crystalline and amorphous P,O, and amorphous At,O,.3P205.2, which is an intermediate product of the dehydration process.
H20, etc. are present uniformly and will crystallize once, but if left in the air, Al2O, 3P, 0, .
2H20 takes moisture from the air as crystal water, At
, O3.3p2056H20 crystals are generated and at the same time expand in volume, destroying the initial crystallized structure and becoming powder-like.

Moreover, when heated to 500° C. or higher, a stable and strong crystalline substance At2O3.3p20 is formed. Furthermore, about 1
At 00℃ higher than 600℃, At,O3・3p
By causing thermal decomposition of 205→At2O, .P2O, +2H20, a stronger heat-resistant product can be obtained. When using a phosphate alone as described above, heating to 500° C. or higher is required.

However, since the base material on which the self-cleaning coating layer is formed is usually made of steel, it is not possible to raise the temperature above 900°C, so it is preferable to heat the base material in the range of 500°C to 800°C. Furthermore, in the case of primary phosphates, the dissociable H at the terminal can be substituted and blocked by a substance with good water resistance.

Since phosphates exhibit acidity in aqueous solution, a substitution reaction occurs between H in the 0H group and the metal. The metals used for this purpose include those that react very violently with phosphates, such as zinc oxide, and those that are slowly reactive, such as At, Si, and Ti.
, Fe, Sn, and other oxides are used. Curing with phosphates and composite oxides is thought to be due to the synergistic action of the formation of metal phosphate salts through neutralization and the accompanying cross-linking reaction of phosphate groups by the metal, and at relatively low temperatures. (120°C to 150°C) to obtain a product with good water resistance. In addition, MgO, Mg(0H)2
, Ca0, Ca(0H)2, asbestos, talc, fly ash, and other basic substances can also be used as hardening accelerators. However, these methods are limited to P (phosphorus) and M (
P when used alone as a phosphate, which is largely controlled by the molar ratio of metal) and has a large effect on bonding, heat resistance, and water resistance.
The smaller the molar ratio of M and M, the better the water resistance, but if the ratio is less than 1, the adhesion and water-solubility stability will decrease.

Although this value varies depending on the type of M (metal), it is usually preferably in the range of 1 to 4. In addition, when a complex oxide is used in combination with a phosphate, the temperature and water resistance are affected by the molar ratio of P and M, and P<! If the molar ratio of l:M is greater than 3, the water resistance will not be improved unless the temperature is high, and if this ratio is small, a product with water resistance can be obtained at a relatively low temperature.

However, P. ! If the molar ratio of -M is, for example, 0.5 or less, it will rapidly condense at room temperature, so when considering the optimum working temperature, the molar ratio of P to M is optimally between 0.5 and 3. Furthermore, the molar ratio of P and M greatly affects the performance of the self-cleaning coating layer.

If the molar ratio of P and M is small, there is no effect, but P/M
As the ratio increases, the performance of the self-cleaning coating layer decreases. This is because P (phosphorus) becomes a catalyst poison, and the greater the number of moles of P, the greater the effect.
Na trigram, P<! When the molar ratio of :M is up to 4.0, the effect is small, but when it exceeds 4.0, the performance deteriorates significantly. Thus, the molar ratio of P to M is most preferably 0.5 to 4.0 in terms of the present invention.

Next, the amount of phosphate added greatly affects the surface hardness of the self-purifying coating layer and the adhesion to the base material.

It must contain at least 5% by weight of phosphate based on the solid content of the catalyst or curing accelerator. That is, if it is less than 5% by weight, the bond between the phosphate and the catalyst is weak and the surface is soft. In addition, the adhesion to the base material is weak and it is easy to peel off. Furthermore, even if a large amount of phosphate is used, the phosphate itself becomes porous when heated, and the catalytic effect is caused by some synergistic effect between the phosphate and the solid content. Alternatively, it seems that it does not affect surface hardness or adhesion. Therefore, the phosphate should be at least 5% by weight or more, but
Adding a large amount will only increase the cost, so 5% by weight or more
50% by weight is preferred. Thus, by using phosphate alone or in combination with a curing accelerator, a coating layer with good water resistance, adhesion, and surface hardness can be obtained.
Furthermore, it has the characteristic that it does not affect the catalytic action. Next, the catalyst constituting the self-purifying coating layer will be described.

Any catalyst can be used as long as it oxidizes and purifies oil scattered during cooking.

Generally, oxides of transition metals such as Cu, Mn, CO, Ni, Fe, and Cr are used, but considering food hygiene, pollution, colorability, cost, etc., MnO2, Mn2
O3, cuO, Fe2O3, Fe, O4, etc. are preferred. Solid acid catalysts such as complex oxides, natural zeolites, synthetic zeolites, acid clay, activated clay and derivatives thereof, silica alumina, silica magnesia, and alumina poria can also be used. In addition, lime aluminate,
Calcium silicate, titanium oxide, zirconium oxide, or alkaline earth metal compounds are also effective in decomposing fatty acids. These catalysts can be used alone or in combination of two or more. Further, these catalysts are mixed with the above-mentioned binder in an appropriate ratio to form a coating on the substrate.

Although the purifying ability of the catalyst does not differ greatly depending on the type of phosphate, monobasic aluminum phosphate is most preferred in terms of mechanical properties and cost efficiency. In addition to the catalyst, various refractory fillers may optionally be added for the purpose of increasing porosity.

Refractory fillers include SiO2, At2O3, MgO, C
In addition to aO, it also includes minerals that contain these as one component.
Next, examples of the present invention will be shown and explained in detail.

Example 1 The above A, C and C were mixed and applied with a spray gun onto a degreased and washed aluminized steel plate with a thickness of 0.8 Wr1n1 and a size of 5 x 10 m, and baked at 550°C for 15 minutes.

50mf of lard was attached to this test piece, and the temperature was 200°C.
When heated for 30 minutes at 50° C. and 300° C., the purifying ability was 32%, 80%, and 98%, respectively.

Further, in order to check the adhesion, the test piece was bent at 180° C. with the coating layer on the outside.

As a result, no peeling between the base material and the coating layer was observed.
As a boiling water resistance test, it was immersed in boiling water for 10 hours, but no abnormality was observed.

The surface hardness was not abraded by copper when an attempt was made to scratch it with a piece of copper.

Example 2 A. Primary aluminum phosphate At2O3・3p20,
・6H20 aqueous solution 10 parts by volume, curing agent ZnO-Si
Part by weight of O2lO C, Catalyst Mn2O3lOO''2, Water 30'' These A, H, C, and II were applied to the base material used in Example 1 and baked at 300° C. for 30 minutes.

The performance of this test piece was evaluated in the same manner as in Example 1.

Purification ability 200℃・・・25$ 250℃・・・75% 300℃・・・94q6 Adhesion: No peeling.

Boiling water resistance: No abnormalities for 10 hours. surface hardness·
・・・・・・・・・Copper did not remove the cutting force. Example 3
B. Aluminum monophosphate (Al2O,・3P20,・6H20) aqueous solution 15
Volume part Portion, Hardening agent (MgO) 0.5 parts by weight C, Catalyst I (MnO2) 50'' 1←2, Catalyst 1 (zeolite) 50 parts by weight E, Refractory filler SiO23O'', Water 40'' These items Test pieces were prepared in the same manner as in Example 2, and their performance was evaluated.

Purification ability 200℃...4096250℃...
...82% 300°C...99% Adhesion...No peeling.

Boiling water resistance: No abnormalities for 10 hours. surface hardness·
......D could not be removed by copper. Example 4
A, primary aluminum phosphate (At2O3・3P20,・6H20) powder mouth,
Curing agent (α-Al2O3) C, catalyst I (CuO) 50
Parts by weight 2, Catalyst (S9-alumina) 50 Parts by weight E, Water 30
Part by weight The above monoaluminum phosphate and α-At2O3 were mixed at a weight ratio of 10:10, 10:5, and 10:2, and the coating performance was evaluated on the substrate used in Example 1. I went.

Example 5 A. Dibasic aluminum phosphate (2At203・3P20,・3H20)B. Second
Magnesium phosphate (2Mg0-P2O,.H2O) C. Dibasic calcium phosphate (2Ca0-P2O5・H2O), catalyst (MnO2) 100 parts by weight, curing agent (ZnO-At2O3) 0.6 parts by weight,
Water 20 parts by weight Samples were prepared using each of A, b, and c in A above.

A sample was prepared in the same manner as in Example 1 using 20 parts by weight, and evaluated. The results are shown below.

Example 6 Catalyst (MnO2) 100 parts by weight Hardening accelerator (MgO) 1'' To the above mixture, 1, 2, 3, 5, 7, 10 aqueous solution of aluminum 9ophosphate was added. , 50 parts by weight were added and applied to the base material used in Example 1.
Heated at ℃ for 30 minutes.

These test pieces were subjected to the same performance evaluation as in Example 1. The results are shown in the table below. As mentioned above, if it is less than 5 parts by weight, the boiling resistance and surface roughness decrease, so it can be seen that 5 parts by weight or more is necessary.

In addition, although the above-mentioned examples have all described self-purification performance for oil scattered during cooking, the self-purification coating layer of the present invention can also be applied to, for example, an atomization type combustor device. It is effective for converting oil into varnish in a broad sense.

Claims (1)

[Claims] 1. Consists of a catalyst and a binder that binds the catalyst to the surface of a substrate, and this binder has the general formula MO・xP_2O_5・y
A self-purifying coating layer characterized in that it is a phosphate represented by H_2O (where M is Al, Mg or Cax, and y is a real number). 2. The self-purifying coating layer according to claim 1, wherein the molar ratio of P and M in the general formula is within the range of 0.5 to 4.0. 3 Phosphate curing accelerator is Zn, Al, Si, Ti,
The self-purifying coating layer according to claim 1 or 2, which contains at least one oxide selected from the group of Fe, Mg, and Sn oxides and composite oxides thereof. 4. The self-purifying coating layer according to claim 1, 2 or 3, wherein the amount of phosphate is 5% by weight or more based on the solid content of the catalyst and curing accelerator.