JPH0328385B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an enameled frit that can be fired at low temperatures, and provides resource and energy savings in enameling processing, as well as widening the degree of freedom in designing enameled parts. BACKGROUND ART One of the drawbacks of enamelware is that the base steel plate is deformed due to distortion during firing. This strain becomes smaller as the thickness of the steel plate increases and as the firing temperature decreases. It is known that this strain hardly occurs at temperatures below 723°C, which is the _A1 transformation point of the steel sheet. Therefore, if you use a hollow frit that can be fired below the _A1 transformation point, you can design a steel plate with a thinner thickness. It is also known that firing at a low temperature reduces defects in enameled ware caused by gas, such as bubbles, pinholes, and flying nails. Furthermore, in recent years, as oil prices have skyrocketed, fuel costs for enameled utensils account for a large proportion, and enamel that can be fired at low temperatures is desired from the viewpoint of resource and energy conservation. Under these circumstances, attempts have been made both domestically and internationally to use low-melting enamel, but it is still insufficient as it does not have the characteristics to replace the current high-temperature enamel. The present inventors have so far developed a transparent frit, a dark-colored frit with excellent adhesion, and a milky white frit. These hollow frits made it possible to develop a wide range of color tones. Problems to be Solved by the Invention However, in recent years, bright pastel tones based on white have become particularly popular. The relatively strong milky pastel color is based on the milky white frit that was developed earlier (Japanese Patent Application Laid-Open No. 1986-
64242), but pastel colors with weak opalescence were impossible. The present invention enables pastel colors with low opalescence, can be fired at a temperature below the _A1 transformation point of steel,
To provide a semi-opalescent enamel frit that is comparable to high-temperature enamel in terms of gloss, hiding power, acid resistance, and water resistance. Means for Solving the Problems The low softening point semi-milky hollow frit of the present invention is
At least as essential components, SiO ₂ , B ₂ O ₃ ,
It contains Na ₂ O, K ₂ O, TiO ₂ , ZrO ₂ and F ₂ . The content of these components is by weight
_SiO2 33-41%, _{B2O3 16-22} %, _Na2O4-10 %,
_K2O9 ~15%, _TiO2 5.5~10%, _ZrO2 5~13.5%,
F ₂ 2 to 10% (all contents below are expressed in weight ratios and are simply expressed in %). Function There are two types of milky white enamel: post-fill type and pre-fill type. The post-fill type adds TiO ₂ as a pigment during mill addition, and the first-fill type adds TiO 2 as a glass component.
This type uses TiO ₂ , ZrO ₂ , and Sb ₂ O ₃ to precipitate milky white crystals during firing, and is also called the recrystallization type. Each type has its advantages and disadvantages, but the pre-filled type is superior in terms of gloss, hiding power, and whiteness. It's excellent. Among them, the TiO ₂ pre-load type is the best. The color tone and emulsion of titanium glaze are greatly affected by changes in the basic composition, and even if the ingredients are similar, they can change greatly by changing the composition ratio. It is generally said that (1) sufficient emulsion cannot be obtained unless the ratio of B ₂ O ₃ /Na ₂ O is increased. (2)
When SiO ₂ is decreased or Na ₂ O is increased, the color becomes brownish. (3) Addition of small amounts of Al ₂ O ₃ increases the emulsion of the frit. (4) When adding 5% of CaO, ZnO, SrO, MgO, etc., MgO has some effect on increasing emulsion, but the others have no effect.
etc. As is clear from the above-mentioned empirical rules for conventional milky white enamel, even if there is nothing special about the raw materials used, the frits produced will differ depending on the method of combining them, and if they are slightly different, the frits produced will be different from their original beauty. You can't get whiteness. Therefore, when discussing the characteristics of frits, it cannot be said that they have the same characteristics just because they have similar compositions. The semi-milky white enamel frit here refers to CI
The opalescence obtained from the color stimulus values X, Y, and Z on the E display is around 70 to 80, and the opalescence of the opalescent frit is 85.
Smaller than the above. Therefore, an enamel film without pigment added has inferior hiding power compared to milky white enamel. However, care must be taken that the semi-milky frit does not take on a yellow, gray or bluish tint, as the pastel colors must not become muddy. In addition, although this milky white enamel frit is not completely milky white, titanium oxide is an expensive raw material and the content of titanium oxide affects the price of the frit.
As with the opalescent frit, the frit composition was determined so that as little titanium oxide as possible would effectively promote opalescence and hiding power. Next, the reasons for limiting the composition of each component of the semi-milky enamel frit of the present invention, which can have a deep pastel tone, will be described. SiO ₂ and B ₂ O ₃ are important oxides as glass-forming oxides, and the proportions of SiO ₂ and B ₂ O ₃ greatly affect the coefficient of thermal expansion, softening point, and water resistance of glass. High-temperature enamel has SiO ₂ of 45% or more and B ₂ O ₃ of around 15%. In order to lower the melting temperature of glass, it is necessary to reduce SiO ₂ , but simply reducing SiO ₂ alone causes the problems described above. Instead of reducing SiO ₂ in conventional low melting enamel,
Many of them use P ₂ O ₅ , PbO, and Sb ₂ O ₃ to achieve low melting, and according to Japanese Patent Application Laid-Open No. 82826/1982, the content of P ₂ O ₅ is set at 20 to 60%. In the frit of the present invention, SiO ₂ 33-41%,
_B2O3 is _16-22 %. From the concept of high-temperature enamel, if SiO ₂ is less than 45%, loss of luster and devitrification will occur and a beautiful enamel surface cannot be obtained. However, in the present invention, ZrO ₂ is contained as a low-melting component. Therefore, 33-41% is sufficient. Similarly to SiO ₂ , B ₂ O ₃ is a factor that greatly affects the surface gloss and corrosion resistance of the frit, and in high-temperature enamel it is around 15%, but in the present invention it is 16 to 22%. here
The ratio of SiO ₂ to B ₂ O ₃ [SiO ₂ /B ₂ O ₃ ] is suitably in the range of 1.6 to 2.5. Outside this range, when SiO ₂ is low and B ₂ O ₃ is high, the enamel surface will foam,
It becomes a dark milky white color and its water resistance deteriorates.
Conversely, if SiO ₂ is high and B ₂ O ₃ is low, enamel cannot be fired at temperatures below 723°C, and the luster will be lost. Next, we will discuss the alkaline component. The essential alkali components in the frit of the present invention are Na ₂ O and K ₂ O. Both Na ₂ O and K ₂ O are important alkaline components for lowering the melting point, but each of these components has an appropriate composition range. The process of emulsification of recrystallized titanium glaze is such that Ti ⁴⁺ , which is incorporated as a glass component in the form of ions during fritting, crystallizes into anatase-type titanium oxide particles during firing, thereby increasing the hiding power. have The size of this titanium oxide crystal particle is 0.2μ
It shows the best emulsion when it is about m. The crystalline form of this titanium oxide is mainly anatase type, and some of it is rutin type. Titanium oxide particles have a higher refractive index among various substances (2.52 for anatase and 2.76 for rutin), and therefore exhibit better hiding power than zircon or antimony glazes. Therefore, in order to efficiently promote emulsification using as little titanium oxide as possible, first of all,
It is necessary that the frit be smooth so that the original refractive index of titanium oxide can be exhibited when it is melted, and secondly that the titanium oxide that has precipitated crystals exists stably in the frit. It is important for the recrystallized titanium glaze to satisfy the above-mentioned requirements, and the appropriate composition range of the alkaline component is limited in order to satisfy this requirement. In other words, if the alkali content is low, the frit will not melt, the titanium oxide will not refract the light, and the frit will reflect diffusely, making it impossible to obtain a beautiful white color. Furthermore, if the alkali content is too large, the precipitated titanium oxide particles and the excess alkali content will react, forming a titanium compound, and titanium oxide will not exhibit its inherent high hiding power of refractive index. For the above reasons, the amount of Na ₂ O in the low softening point semi-milky hollow frit of the present invention is 4 to 10%, and the amount of K ₂ O is 9 to 15%. this
The amount of Na ₂ O is lower than that of high temperature hollow frit.
It's not a lot. Although this is a small amount from the general concept of low-melting enamel, the appropriate range is 4 to 10% because if the amount of Na ₂ O increases, it will take on a yellowish tinge, reduce gloss, and have poor acid resistance. be. A suitable range for the amount of _K2O is 9-15%. _K2O is
Although it contributes less to easy solubility than Na ₂ O, it is an essential component for white color development. However, if too much K ₂ O is added in excess of the above range, no white color will be produced. Both Na ₂ O and K ₂ O can be substituted to a certain extent, but Na ₂ O is 4 to 10% and K ₂ O is 9 to 15%.
It is necessary to do this within the range of the sum of both [Na ₂ O
+K ₂ O] is 15 to 20%, and the ratio of both [Na ₂ O/
_K2O ] is preferably 0.4 to 0.9. Furthermore, in the present invention, it is also possible to contain Li ₂ O as an alkali oxide as an external component. Li ₂ O has an effect on the easy solubility of frit.
Although it is more effective than Na ₂ O and K ₂ O, if it is added in excess of 3%, the gloss will drop sharply. Also Li ₂ O
Addition of more than 3% also has an adverse effect on white color development. Next, let's talk about _TiO2 . TiO ₂ is a compound that gives milky white to the frit, and its amount is closely related to the milky whiteness of the produced enamel. The content of _TiO2 will be discussed later
Combined with the effect of ZrO ₂ , it may be 5.5 to 10%. 5.5%
If it is less than 70%, crystal precipitation is insufficient and the milkiness is 70%.
As a result, the whiteness is insufficient and dull. When it exceeds 10%, the milkiness exceeds 80, resulting in a strong white pastel color. Next, ZrO ₂ will be described. _ZrO2 is usually a thermally stable compound,
In the glass frit component, it melts at the melting temperature of the frit (1100-1300°C). Furthermore, the appropriate amount of ZrO ₂ in the frit fixes the alkaline component without increasing the softening temperature of the frit. Therefore, the effect of adding ZrO ₂ is to suppress the reaction between excess alkali and precipitated TiO ₂ .
In the present invention, it is largely due to this ZrO ₂ that satisfactory opalescence can be obtained even if the content of TiO ₂ is small compared to high-temperature enamel. Moreover, an appropriate amount of ZrO ₂ can be used without increasing the softening temperature.
Improves gloss and water resistance. The content of _ZrO2 in the present invention is 5-13.5%. If it is less than 5%, the alkaline component in the frit will not be fixed but will be liberated, resulting in poor water resistance and failure to suppress the reaction with TiO ₂ , making it impossible to obtain a satisfactory milky white. On the other hand, if it exceeds 13.5%, ZrO ₂ crystals will precipitate, making it impossible to obtain products with excellent gloss and opalescence. Also, the sum and ratio of TiO ₂ and ZrO ₂ is important; [TiO ₂ + ZrO ₂ ] is 12-18%, [TiO ₂ /ZrO ₂ ]
is preferably 0.6 to 1.3. Next, we will discuss _F2 , which is a typical acidic component. _F2 is an important acidic component in the frit, and is especially indispensable for titanium glazes. As mentioned earlier, TiO ₂ reacts more easily with alkal components than acidic components, so it requires more acidic components than other high-temperature enamels. _F2 is a strong acidic component and is an essential component in the present invention, with an optimal range of 2-10%. _F2 remains as a final frit component at a rate of 50 to 70%, and the rest is scattered during frit manufacturing. This scattered _F2 has the effect of stirring the frit and the effect of maintaining an acidic atmosphere inside the frit during manufacturing, and is important, but the range of _F2 in the present invention is limited to the effect of stirring the frit inside the produced frit. The amount of _F2 contained. In addition, inside the frit
Although it is not clear whether it is contained in the F ₂ state, it will be expressed as F ₂ according to convention.
If the amount of _F2 is less than 2%, it will not be possible to neutralize the alkaline component, and therefore a satisfactory milky white will not be obtained. On the other hand, if it exceeds 10%, the inside of the frit will be too acidic, causing foaming and cracking on the baked enamel surface, making it impossible to obtain a good surface condition. Therefore, a suitable range for the amount of _F2 is 2-10%. Furthermore, in the present invention, it is also possible to contain P ₂ O ₅ as an acidic oxide as an external component. In a completely opalescent frit containing a large amount of TiO ₂ , P ₂ O ₅ is highly effective as a stabilizer for titanium oxide. However, within the TiO ₂ content range of the present invention, there is no great effect, but it can be used to finely adjust the milky white color and hiding power in delicate relation to the content of other components. If P ₂ O ₅ exceeds 1.5%, the yellow color becomes strong and it becomes impossible to obtain a product with excellent gloss. Other external components of the present invention include CaO, ZnO,
It can also include MgO, BaO, _SrO and _Al2O3 . If these oxides are added in small amounts, they do not essentially change the frit made up of the above-mentioned composition ratios, but if they are used in large amounts, they reduce the color tone, surface condition, and gloss. However, depending on how they are used, these components also contribute to adjusting the viscosity and thermal expansion of the frit, improving its water resistance, and improving its surface condition. Therefore, when added, it is necessary to use it within a range not exceeding 5%. Next, the raw materials constituting the frit of the present invention will be described. Silica powder, feldspar, etc. can be used as raw materials for SiO ₂ , but care must be taken as Fe ₂ O ₃ as an impurity will color the frit a reddish-brown color. B ₂ O ₃ includes H ₃ BO ₄ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇・
There are boric acid and borax represented by 10H ₂ O, but boric acid is preferable in terms of maintaining an acidic atmosphere during fritting and melting. Na ₂ O can be obtained from single components such as Na ₂ CO ₃ and NaNO ₃ , but it can also be obtained from borax, sodium silicofluoride, and quartzite. Similarly, K ₂ O includes KNO ₃ , K ₂ CO ₃ and potassium silicofluoride. For Li ₂ O, use Li ₂ CO ₃ and natural ore spodium. Naturally produced ZrO ₂ contains Fe ₂ O ₃ impurities,
Also, since purified products are expensive, ZrO ₂ and SiO ₂
It is preferable to use zircon (ZrO ₂ .nSiO ₂ ), which is a compound of This zircon is not only cheap, but also melts more easily than ZrO ₂ alone during frit melting. TiO ₂ has anatase type and rutile type.
Either is fine when used as a raw material. _F2 is in the form of compounds such as LiF, NaF, KF,
There are CaF ₂ , Na ₂ SiF ₆ , Na ₃ AlF ₆ , K ₂ SiF ₆ , etc.
Any material may be used, but the raw material is determined after considering the amount of cations. P ₂ O ₅ is appropriately selected from Ca ₃ (PO ₄ ) ₂ , Na ₂ HPO ₄ , and NaH ₂ PO ₄ depending on the composition ratio. Other examples of CaO include CaCO ₃ , Ca(OH) ₂ , CaF ₂ ,
Ca ₃ (PO ₄ ) ₂ and dolomite, ZnO is zinc white,
ZnCO ₃ , MgO is MgCO ₃ , MgO and dolomite,
BaO is BaCO ₃ , Ba(NO ₃ ) ₂ , BaF ₂ , SrO is
SrCO ₃ , Al ₂ O ₃ is alumina, Al (OH) ₃ and cryolite,
Uses feldspar etc. as raw material. The above-mentioned raw materials are mixed according to their respective composition ratios. Thoroughly dry mixed raw materials are 1100 ~
Heat and melt at 1300℃. Since the heating temperature and time change the final composition ratio of the frit components, they must be well controlled. After dissolving the raw materials, 20~
It is important to allow the vitrification to proceed for 40 minutes, stirring as necessary. If held for a long time, the alkaline components will sublimate, so do not hold it too long. After melting, the glass is placed in water and rapidly cooled. This is dried to obtain the desired low softening point semi-opalescent hollow frit. Examples Example 1 F ₂ 8%, Na ₂ O 7%, K ₂ O 12%, CaO 1%, TiO ₂ 7
%, ZrO ₂ 8% and the balance 57% SiO ₂ and B ₂ O ₃ and melted. Melting temperature is 1200℃
After melting the raw materials, the temperature was kept at the same temperature for 30 minutes. Note that SiO ₂ and B ₂ O ₃ were mixed to have the compositions shown in Table 2. The preparation example in Table 2 No. 4 is 137 g of silica powder, 108 g of borax (Na ₂ B ₄ O ₇ ), 27 g of boric acid, 56 g of zircon (ZrO ₂・SiO ₂ ), 32 g of anatase type TiO ₂ ,
42 g of KNO ₃ , 7 g of fluorite, and 70 g of K ₂ SiF ₆ . Mill additives were added to the produced frit and mixed by pulverization in a ball mill to create a slip. Two types of slips were prepared according to the formulations shown in Table 1: one with no pigment added and one with yellow and green pigments added.

[Table] The glaze was applied using a spray gun onto a steel plate for enamel (SPP material), which had been pickled and nickel-treated in advance to a film thickness of 100 to 150 μm, and was 100 mm x 100 mm in size and 0.6 mm thick. Summer. After drying, 710℃
It was fired for 5 minutes and used as a sample. A sample of Slip 1 was used to determine the degree of yellowness of opalescence, and a sample of Slip 2 to which pigment was added was used to check the color difference from the standard color of high-temperature enamel, gloss, surface condition, and water resistance. The evaluation method was as follows. (1) Opalescence L, a, and b obtained from color stimulation values X, Y, and Z according to CIE display were measured using a color difference meter, and opalescence W was calculated using the formula shown below. W=100−√(100−) ² + ² + ² The larger the W value, the more whitish the color becomes. usually,
A frit with a W value of 85 or higher has good hiding power and feels white to the eye, and a frit with a W value of 70 to 80 is preferable for deep pastel tones, which gives a slightly dull feeling when no pigment is added. (2) Yellowness Yellowness N is the color stimulus value X measured with a color difference meter,
It was calculated using the formula shown below for Y and Z. N=100(1.28X-1.06Z)/Y When the N value is large on the + side, the yellowish tinge becomes strong, and when the value is large on the - side, the color becomes bluish. There are many pastel tones such as red, yellow, green, blue, purple, and brown, and bright colors are preferred, but in order to accommodate these, the color of enamel without adding pigments should be on the yellow side. It is preferable to use a color that does not lean towards the blue side. (3) Color difference L, a, and b of the enamel sample using the standard color and Slip 2 were measured using a color difference meter, and the color difference (ΔE) was calculated using the formula shown below. ΔE=√( _-S ) ² +(- _S ) ² +(- _S ) ² L, a, b: Lightness of sample, chromaticity index L _S , a _S , b _S : Lightness of standard color, chromaticity index Standard color L _S , a _S , b _S made from high temperature enamel
are 54.7, -16.2, and 21.7, which is a slightly yellowish green pastel color. Of course, the smaller the color difference (ΔE), the better.
The following are preferred. (4) Gloss The gloss of the enamel surface was measured using a crossmeter (Nippon Denshoku Industries VG-107). Usually, the gloss of the enamel surface is preferably 90 or higher. (5) Surface condition Observe the surface condition of the enamel surface, and express the occurrence of cracks, foaming, yuzu skin, or unevenness on the surface as ×, △, or ○ depending on the degree. × means a lot of occurrence, ○ means no occurrence, and △ means a little occurrence. (6) Water resistance The water resistance of enamel is determined by immersing the test plate in hot water at 98℃ for 1 hour. If the weight difference between before and after is less than 10 mg/dm ² , it is ○, and if it is 10 to 30 mg/dm ² , it is △. , 30
Those with mg/dm ² or more are indicated by x. The results obtained by the above evaluation method are
Shown in the table.

[Table] As is clear from Table 2, the appropriate value of SiO ₂ is
33-41%, the appropriate value _{of B2O3} is 16-22%,
It is preferred that the _SiO2 / _B2O3 ratio is 1.6 to _2.5 . Example 2 As a constituent of the frit, SiO ₂ is 37 to 39%,
_B2O3 18-20%, _F2 6-8 _% , _Li2O 1.1-1.3
%, CaO 1.1-1.3%, _ZrO2 7.5-8%, _TiO2
is within the range of 6.5 to 7%, and [Na ₂ O + K ₂ O] is 19%
The W value and other values were measured by changing Na ₂ O and K ₂ O. Sample preparation was the same as in Example 1. The results obtained are shown in Table 3.

[Table] As is clear from Table 3, the appropriate value for Na ₂ O is 4
~10%, while the appropriate value for _K2O is 9-15%.
Na ₂ O/K ₂ O is preferably 0.4 to 0.9. Example 3 As a constituent of the frit, SiO ₂ is 37 to 39%,
_B2O3 18-20%, _F2 6-8 _% , _Li2O 1.1-1.3
%, _Na2O 7-8%, _K2O 11-12%, CaO
1.1~1.3%, _ZrO2 within the range of 7.5~8%
Figure 1 shows the W value at slip 1 and Figure 2 shows the ΔE at slip 2 when TiO ₂ is varied. As is clear from the figure, when TiO ₂ is less than 5.5%, the W value is less than 70 and the whiteness is weak, and the ΔE is 5 or more, and when it exceeds 10%, the W value exceeds 80 and the white is strong pastel. Because of the color, ΔE is 5 or more. Therefore, the optimal range for _TiO2 is 5.5-10%. Example 4 As a constituent of the frit, SiO ₂ is 37 to 39%,
_B2O5 18-20% _{, F2} 6-8%, _Li2O 1.1-1.3
%, _Na2O 7-8%, _K2O 11-12%, CaO
FIG. 3 shows the W value when ZrO ₂ was varied in the range of 1.1 to 1.3% and TiO ₂ in the range of 6.5 to 7%. As is clear from the figure, as ZrO ₂ increases, W
The value increases, but if it exceeds 8.5%, the glass becomes difficult to melt and the W value decreases. If it exceeds 13.5%, the gloss will be less than 60 and the surface condition will be poor. If it is less than 5%, the coexisting alkali and TiO ₂ will react, resulting in a low W value. Example 5 In the components of the frit of Example 4,
FIG. 4 shows the relationship between the amount of Li ₂ O and the W value when ZrO ₂ is set to 7.5 to 8% and Li ₂ O is varied. Li ₂ O has the highest W value at around 1.5%. Furthermore, the gloss is around 100 up to 2%, but becomes less than 90 when it exceeds 3%, and when it approaches 4%, the surface condition becomes yuzu skin. Therefore, the appropriate amount of Li ₂ O is 3% or less. Example 6 In the components of the frit of Example 4,
FIG. 5 shows the W value when ZrO ₂ is 7.5 to 8% and P ₂ O ₅ is varied. As is clear from the figure, the amount of P ₂ O ₅ does not have a large effect on the W value. However, as the amount of P ₂ O ₅ increases, it becomes yellowish and at the same time the gloss decreases. In the reduced pigment slip, P ₂ O ₅ is 2%
The gloss will be below 80. Therefore, P ₂ O ₅
The optimal range for is 1.5% or less. Example 7 In the components of the frit of Example 4,
FIG. 6 shows the W value when ZrO ₂ is 7.5 to 8% and F ₂ is varied. As is clear from the figure, the W value has a maximum value in the optimum range of _F2 , and the W value is 70 or more at 4 to 13%. This amount of _F2 is a theoretical value at the time of addition, and was determined by chemical analysis of this frit.
When the amount of _F2 was determined, it was 2 to 10%. The optimum range is therefore 2-10%. 2%
When the amount is less, the W value is low, and conversely, when it exceeds 10% (13% as a theoretical value), foaming is observed on the surface. Example 8 Frit composition: SiO ₂ 37%, B ₂ O ₃ 19%,
_F2 7%, _Li2O1 %, _Na2O7 %, _K2O11 %, CaO1
%, TiO2 ₇ %, ZrO2 ₈ %;
2% ZnO was added. Using this frit, a sample was prepared according to Example 1, and the W value was measured to be 78, N value -1.5, ΔE3.6, gloss 100,
Both surface condition and water resistance were rated ○. Example 9 A sample prepared in the same manner as in Example 8 by replacing ZnO with the same amount of MgO had a W value of 77, N
The value was -0.5, ΔE3.3, gloss 97, surface condition, and water resistance were all ○. Example 10 A sample prepared in the same manner as in Example 8 by replacing ZnO with the same amount of BaO had a W value of 77 and a N
The value was -0.8, ΔE3.5, gloss 98, surface condition, and water resistance were all ○. Example 11 A sample prepared in the same manner as in Example 8 by replacing ZnO with the same amount of SrO had a W value of 77, an N value of -0.6, ΔE3.6, gloss of 98, surface condition, and water resistance.
It was hot. Example 12 A sample prepared in the same manner as in Example 8 by replacing ZnO with the same amount of Al ₂ O ₃ had a W value of 77 and a N
The value was -0.3, ΔE3.4, gloss 94, surface condition, and water resistance. Effects of the Invention As is clear from the above examples, according to the present invention, a pastel-like low-melting enamel with relatively weak whiteness can be obtained.

[Brief explanation of drawings]

The drawing shows the relationship between the amount of the constituent components of the frit and the W value or ΔE of the obtained enamel.
Figure 1 shows the relationship between the amount of TiO ₂ and the W value, Figure 2
The figure shows the relationship between the amount of TiO ₂ and ΔE, and Figure 3 shows the relationship between the amount of TiO _{2 and} ΔE.
Figure 4 shows the relationship between Li ₂ O amount and W value.
FIG. 5 is a diagram showing the relationship between the values. FIG. 5 is a diagram showing the relationship between the amount of P ₂ O ₅ and the W value. FIG. 6 is a diagram showing the relationship between the amount of F ₂ and the W value.

Claims (1)

[Claims] 1. At least SiO ₂ , B ₂ O ₃ , Na ₂ O, K ₂ O,
TiO ₂ , ZrO ₂ , and F ₂ are essential components, and their content in weight ratio is SiO ₂ 33-41%, B ₂ O ₃ 16-22%,
_Na2O4 ~10%, _K2O9 ~15%, _TiO2 5.5~10%,
Low softening point semi-milky hollow frit with _ZrO2 5-13.5%, _F2 2-10%. 2 Sum of contents converted to weight ratio [Na ₂ O + K ₂ O]
is 15-20%, [ _TiO2 + ZrO2 _] is 12-18%, the content ratio [ _Na2O / _K2O ] is 0.4-0.9, [ _SiO2 / _{B2O3 ]}
1.6 to 2.5, and [ _TiO2 /ZrO2 _] is 0.6 to 1.3. The low softening point semi-opalescent hollow frit according to claim 1. 3. The low softening point semi-opalescent hollow frit according to claim 1 or 2, which contains 3% by weight or less of Li ₂ O. 4. The low softening point semi-opalescent hollow frit according to any one of claims 1 to 3, which contains _1.5 % by weight or less of _P2O5 . 5. Any one of claims 1 to 4 containing at least one selected from the group consisting of CaO, ZnO, MgO, BaO, SrO and Al ₂ O ₃ in a total amount of 5% by weight or less Low softening point semi-milky enamel frit.