JPS58151476A - Manufacture of enameled product - Google Patents

Abstract

PURPOSE:To enhance the impact resistance of enamel, by enameling a product using a low m.p. glass composition contg. Li2O and by treating the surface of the enameled product with a molten potassium salt contg. a boric acid compound. CONSTITUTION:Enamel is formed on the surface of a metallic product using a low m.p. glass composition contg. at least 5mol% Li2O to obtain an enameld product. A molten potassium salt such as molten potassium nitrate contg. at least one of sodium borate and borax is brought into uniform contact with the surface of the enameled product to substitute K ions for Na ions on the surface of the enamel by ion exchange. Thus, a hardened enameled product with re- markable enhanced impact resistance can be manufactured stably without reducing the productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the production of a wafer product with excellent impact resistance.

Haurou is made by baking or coating a metal surface with a glass material, and it is possible to improve durability by corroding the metal and add beauty by coloring the glass material. Because of this, the products include pots, bathtubs, wall materials, and f-resistant
Widely used in il tanks and sanitary equipment.

Conventional enamel glass frit has a fairly high firing temperature, so when it is baked onto a thin iron plate, the amount of thermal deformation of the thin iron plate increases, resulting in poor dimensional accuracy of the resulting enamel product.

In order to solve this problem, it was considered to use glass frit with a low melting point as enamel frit, but such frits contain large amounts of polluting substances such as Pb, Cd, and Ag. It has the disadvantage of being harmful and expensive because Ag and the like are expensive.

Moreover, the surface performance of the glassy coating formed by such a frit is much worse than that of the glassy coating formed by the above-mentioned enamel frit, so that it could hardly be put to practical use.

In view of these circumstances, the inventors have previously proposed a low melting point glass composition containing at least 5 moles of Li2O.

All of the above-mentioned problems can be solved by using this low-melting point glass composition to make a wet product. However, it has been found that this low melting point glass composition also has other problems. This means that it is not possible to obtain a surface strength that satisfies the impact resistance necessary for a wax product.

In other words, since the surface of the paper is glassy, it is easily chipped or peeled off due to impact.

So0*J6! - If something like losing the metal parts or rusting occurs on the metal parts, it would be fatal for a crawling product. Therefore, there is a strong demand for a crawling product to have excellent impact resistance.

Regarding the strengthening of such enamel, conventionally, most of the emphasis has been placed on the adhesion to the metal. Washing and nickel immersion improved adhesion with the glassy coating and improved impact resistance. However, even if such pretreatment is performed to improve adhesion, the strength of the vitreous material itself is only III%A, and a material with sufficient impact resistance has not yet been obtained.

On the other hand, conventional methods for strengthening glass include physical strengthening methods and chemical strengthening methods, which have actually been effective for plate glass. However, the application of these methods to enamel has not yet been put into practical use for the following reasons.

■ Physical strengthening method This method strengthens the glass plate by heating it to near its softening temperature and rapidly cooling it to create a temperature difference between the surface and the inside of the glass plate. If the glass layer is not thick to a certain extent, the effect will be low, and especially if the glass layer is as thin as 0.3 to 1.0 mm, such as enamel, the effect will not be sufficient.

■ Chemical strengthening method This method creates thermochemical ion exchange between the glass and the metal salt by immersing the glass product in a monovalent metal salt with a larger ionic radius than the alkali metal ions in the glass. This is a method of strengthening glass by applying compressive pressure to the glass due to the difference in ionic radius, but in this case, it takes a long time (about 40 to 60 hours) to treat with molten salt, so it is difficult to For products that are continuously produced, such as those that are manufactured continuously, this can cause productivity to deteriorate. Also, keeping the glass near its strain point temperature for a long time can cause pinholes.

This invention was developed in view of this situation, and it is
In order to strengthen Tokudai Hauro products using a low melting point glass composition containing O, we decided to adopt an ion exchange method using molten potassium salt, and by adding a boric acid compound to the melting power Q rum salt. By uniformly bringing the molten potassium salt into contact with the surface of the floating wax, so-called ion exchange, which replaces the sodium ions on the surface layer with potassium ions, is promoted. A significantly improved reinforcement of impact properties provides a process for producing enamel products that makes it possible to obtain enamel products.

The gist of this invention is a method for producing an enamel product, which is characterized in that the enamel obtained using a glass composition containing at least 45 moles of LiO is surface-treated with an am potassium salt containing a monoboric acid compound. This will be explained in detail below.

In making the enamel used in this invention, L
A low melting point glass composition containing at least 45 moles of i1O is used. To give an example including compositions other than LixO, a composition of 98 mol or more excluding water is 5iOa; 56 to 63 mol IhOs
; 3M-8 mol TiO2, 3-6 mol Zr0z; 34 g-v-ru Na
Low melting point glass compositions such as fluoride (Fz; converted to 3 to 7 mol), or 9% of the composition excluding water.
The composition of 8 mole tatami or more is 5i (h;
；-6～10mol゛ゝTi(h+
ZrO2; 5-10 mol% Nm*O+Li5O;
23 to 26 moles of fluoride (F); 3 to 26 moles
The mother glass is a glass composition consisting of
For K, Mo5s and/or W (h is 0.5~L
A low melting point glass composition containing 5 mol or more of LhO is preferably used, but a low melting point glass composition that contains 5 mol or more of LhO and that causes thermal deformation of a thin metal substrate for a crawler by 1 kv% is preferably used. It is not limited to the above-mentioned low melting point glass composition as long as it is a material.

The raw material for the low melting point glass composition that becomes sluggish is a raw material that produces an amm acid component oxide or a mixture of these oxides by firing, or a raw material that produces a fluoride component oxide by firing. Any raw material can be used as long as it produces fluorine for the purpose of fluorine. As for 1 to 4,
For example, silicic anhydride, sodium carbonate, sodium sulfate, sodium chloride, sodium silicate, boric acid, sodium borate, lithium carbonate, zirconium oxide, titanium oxide, zirconium silicate, sodium fluoride, lithium fluoride, sodium silicofluoride. Molybdenum II,
Examples include tungsten oxide.

This low melting point glass composition is manufactured as follows.

0) Select appropriate raw materials from the above raw materials, and thoroughly grind and mix them at room temperature, heating if necessary. Of course, the glass may be melted without pulverization and mixing.

←) The above mixture is heated and fired in a furnace to melt and vitrify it.

(c) Fi800-1300 at the final stage of glass melting
Melt for 1-4 hours at 'C. Stir in between if necessary.

(ii) In addition, when melting the glass, pre-firing may be performed if necessary. For example, when sodium carbonate and boric acid are used, the raw materials are first thoroughly mixed and reacted at room temperature. At this time, heat if necessary. Next, it is dehydrated while reacting at 1150 to sOO°C for 1 to 3 hours. In this way a solid is obtained. Next, crush it. The next step is to melt the glass at Kf→. In this way, dehydration when melting the glass,
Since the decarbonation gas is almost linear, it is safe and convenient because no boiling over occurs from inside the crucible.

(e) In addition to the above, when a raw material containing water, a sulfate, or an ammonium salt is used, it is preferable to carry out the pre-calcination described above before melting.

(f) The molten glass should be thrown into water and cooled quickly, or thick
Pour onto a griddle to cool.

(→ The obtained glass is processed using a bot mill or vibration mill.

Finely grind it using a grinder. In this way, a low melting point glass composition is obtained.

Next, the case where a substrate such as a thin iron plate is coated with the glass composition obtained in this manner will be described. In other words, in the case of dry glazing, the glass-coating material is mixed with pigment, and in the case of wet glazing, pigments, additives such as carboxymethyl cellulose, gum arabic, etc. are added as necessary according to conventional methods, and water-based slip is added. It is then glazed, dried if necessary, and then fired to create enamel.

This invention strengthens the enamel surface of the enamel thus obtained, and utilizes an ion exchange reaction to strengthen the enamel surface. In this invention, the first example of the molten potassium salt used in the ion exchange reaction is potassium nitrate (melting point: 330°C). This is because this material has a low melting point and is preferable.

Other potassium salts include potassium hydrochloride (melting point 790°C);
Examples include sulfuric acid (melting point: 1069°C) and potassium chloride (melting point: 1,340°C), but if they are used in large quantities, the ion exchange processing temperature will become high, causing pinholes to form on the surface of the floating wax. easy. Among the boric acid compounds added to the bath-molten potassium salt, at least one of sodium borate and boric acid is preferably used.

By adding a boric acid compound to the potassium salt, the floating wax surface is quickly and evenly coated with the potassium salt due to the good contact effect (due to increased wetting) between the floating wax surface and the potassium salt. Ru. Since sodium ions on the surface layer are quickly replaced with potassium ions, uniform ion exchange occurs within a short time, and the floating surface layer is sufficiently strengthened.

The amount of Minato melted potassium salt Kr & boric acid compound to be added is:
Preferably it is 1 to 10% by weight. If the amount of the boric acid compound added is less than 1 weight, the molten potassium salt will not be able to bring the molten potassium salt into contact with the surface of the wax (wetting). Tend.

The strengthening treatment of the crawling surface is usually carried out as follows. That is, by spraying or applying a mixed saturated water bath solution of molten potassium salt to which a boric acid compound has been added, or by immersing the enamel in the above mixed saturated aqueous solution, the enamel surface can be saturated with the above mixed saturated water solution. After coating with an aqueous solution and drying, apply ion exchange treatment to the enamel, cool to a point where the reinforcement of the enamel surface layer is not eliminated by re-ion exchange, and then wash the remaining salt with hot water. Remove. If necessary, after drying, the surface of the product is once again coated with a mixed saturated water bath solution of the potassium salt, heat treated again to perform ion exchange treatment, and then cooled in the same manner and washed with warm water. Try to remove it.

This results in a more uniform reinforced surface.

According to this invention, the Flowing product has excellent impact resistance, and has no pinholes and is aesthetically pleasing. In addition, since ion exchange is promoted, product productivity is improved.

Examples will be described below.

[Example 1] 5i (h 58 mol) as a low melting point glass composition.

B snow 0.7.5 mol, Ti 0.4.7 mol, Zr
0z 4.8 mol IG, NaxO' 12.5 mol,
12.5 moles of LizO.

Using a frit containing 5.0 moles of F2 component, it was made into a slip and painted on a substrate obtained by applying the usual pretreatment to an iron plate for enameling, and was enameled at 720'C for 6 minutes. Created a board.

Next, KNOa / NazB + Oy ・1GHzO
A saturated aqueous solution of - was mixed at a (95/5) tD weight ratio.

This was sprayed on the porcelain board as a liquid and heated to 120°C.
After drying for S minutes at
%, and then washed with 8G'C warm water. Show the results on Stripe 1@.

[Example 2] KNOa/1 (C1
/3Naeg0 ・BsOs (8G/12/8)
The same treatment as in Example 1 was carried out using a saturated aqueous solution mixed at a weight ratio of 1!1! It was shown to.

[Comparative Example 1] As a comparative example, the untreated crawler board prepared in Example 1 was used.
The results are shown in No. 111.

(Margin below) Based on the results shown in Appendix 1111, it is recognized that Examples 1 and 2 are superior to Comparative Examples.

Patent applicant Matsushita Electric Works Co., Ltd. Agent: Patent Attorney Takehiko Matsumoto

Claims (2)

[Claims] (1) A method for producing an enamel product, which involves surface-treating enamel obtained using a low-melting glass composition containing at least 5 moles of Lim0 with a molten potassium salt containing a boric acid compound. (2) A method for producing an enameled product according to claim 1, using at least one of sodium borate and boric acid as the boric acid compound. (-The method for producing a wax product according to claim 111, in which potassium nitrate or a salt mainly composed of molten salt is used as the latent molten potassium salt.