SK102997A3 - Method for producing leadless mixtures of crystal glass - Google Patents

Abstract

To the dose of the mixture containing instead of PbO as the raw material TiO2, and which is composed of 50 to 60 wt. % SiO2.4 to 14 wt. % K 2 O, 10 to 20 wt. % BaO and 3 to 10 wt. % TiO 2 is added to suppress the color caused by the presence of TiO 2 by 1.0 to 5.0% by weight. Na-NO3 or 0.3 to 2.0 wt. % BaO 2 and at the same time 0.2 to 1.0 wt. Sb2O3 or As2O3 as a defoaming agent. Instead, 0.5 to 2.0 wt. NaSb (OH) 6, which also acts as anti-foaming agent against staining.

Description

Process for producing lead-free crystal glass mixtures

Technical field

The present invention relates to the manufacture of crystal glass compositions which resemble or can be regarded as crystal glass without being lead (Pb).

BACKGROUND OF THE INVENTION

Typically, lead-containing glass is used as crystal glass for the production of kitchenware or similar products. The characteristics of this glass is, in short, that it is massive, that it has a high refractive index of light and exhibits high light scattering, and that it is easily fusible, which are properties, in principle, caused by PbO. Although the content of PbO varies widely, it is generally 24 to 26 percent by weight.

Since crystal glass contains a lot of lead, which is very toxic, when used for the production of crockery, it can have an adverse effect on human health. This makes the reduction of PbO content very urgent.

For this reason, the applicant of the present application has proposed in Japanese patent application no. Heisei 6-183774 glass blend that does not contain lead at all but has the same properties as lead-containing crystal glass. The glass blend consists of SiO 2, TiO 2 ^to provide high refractive index and high scattering, BaO to provide high density and high refractive index, KO to suppress staining by Fe and Na 0 ions to reduce the melting point as the basic components.

However, since the glassy composition contains TiO (titanium dioxide) as the raw material instead of PbO, the glass tends to turn yellow due to the coexistence of TiO 2 with the impurities coming from the raw material.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a process wherein a crystal glass composition that contains TiO as raw material 2 instead of PbO can be produced by preventing the development of a yellowish color in the glass composition caused by TiO 2.

In order to achieve this object, it is an aspect of the present invention to provide a method for producing a lead-free crystal glass composition comprising SiO, TiO to increase the refractive index and light scattering, BaO to increase the density and refractive index, KO to suppress staining with Fe ions comprising the step of adding to the batch a mixture consisting of 50 to 60 weight percent SiO, 4 to 14 weight percent K 2 O, 10 to 20 weight percent BaO, and 3 to 10 weight percent TiO, NaNO (sodium nitrate)

3 in an amount of 1, 0 to 5, 0 by weight or BaO (barium peroxide) in an amount of 0, 3 to 2.0 by weight to remove the coloration resulting from 3 to 10% by weight of TiO and one of Sb O (oxide 2 2 3). antimony (III) and As O (arsenic acid) in an amount of 0.2 to 2%

1, 0 wt.

Preferably, the batch composition contains CaO to compensate for the high temperature viscosity increase due to BaO, and the BaO and CaO content is 10 to 20 weight percent, provided the BaO / CaO ratio is > 2.

The method of the present invention, in reducing the yellow color of TiO ^, is ^the glass melt glue, which is added as an oxidant and NaNO BaO and Sb as an antifoaming agent and about As 0th Each of the compounds is added in an appropriate amount. In particular, since the content of TiO in the batch mixture is 3 to 3 by weight, when using NaNO as an oxidizing agent, 3 is added in an amount of 1.0 to 5.0 by weight, but when using BaO2 this is added in an amount of 0.3 to 2. 0 wt. When Sb 0 is used as a defoaming agent, this is added in an amount of 0, 2 to 1.0, by weight, and also As O is added in an amount of 0 to 2, by weight.

In glass, such as lead-containing crystal glass, the combination of NaNO with Sb O or As O is commonly used as a blackening environment to improve the foaming of the glass. The present inventors have found that, in addition to acting as a blackening agent, the oxygen produced at higher temperatures acts as an oxidizing agent that oxidizes TiO 2 and thereby suppresses the formation of an undesirable yellow color. Use of only one compound from Sb O or

As 0, or just an oxidizing agent such as NaNO, has no such effect as the combination. The results of experiments performed to confirm these effects were compared on the light transmittance curves in the wavelength range of visible light. The results are shown in Figure 1. When the glass absorbs light in the shortwave region in close proximity to ultraviolet radiation, the glass looks yellow.

Although Figure 1 illustrates only the results of the Sb 0 experiments, it has been verified that As O has similar results.

3 2 3

The glassy mixture is composed, except for SiO, K O,

2 basic constituents, also from small amounts of Li O, ZrO and B O 2 2 2 3

The content of these components is shown in the table. In the table, RO means a general presentation of BaO and CaO, a

BaO and TiO as 2

R 0 is generic for 2

It should be noted that all zentation

Na 0, K 0 and Li 0.

The data in the following description are percentages by weight.

Table l

component Content in% by weight. Sio ₂ 50.0 to 60.0 RO 10, 0 to 20.0 * 2 ° 10, 0 to 20, 0 tío ₂ 3, 0 to 10, 0 ZnO 5, 0 to 15, 0 zro ₂ 0.0 to 2.0 ^B 3 ° 3 0, 0 to 2.0 Oxidizing agent NaN0 ₃ 1, 0 to 5, 0 BaO ₂ 0.3 to 2.0 Defoaming agent ^Coll 2 ° 3 0, 2 to 1.0 ^te 2 ° 3 0, 2 to 1.0 Oxidizing antifoam agent NaSb (OH) 0.5 to 2.0

In the process for producing the vitreous blend of the present invention, TiO and BaO are used as raw materials instead of PbO and refractive index, and the light scattering value is increased by TiO 2, while density and refractive index are increased by BaO.

TiO is effective in increasing the refractive index and scattering value of 2 (reducing the Abbe number) and is necessary in the present invention to replace PbO. Where the TiO is less than 3.0 wt%, the refractive index and scattering index values cannot be achieved. On the other hand, if the TiO content exceeds 10.0 wt%. , the tendency to yellow will increase significantly, and consequently, even if added

NaNO or BaO as an oxidizing agent having a decolorizing effect of 32 and Sb O or As O as an antifoaming agent cannot completely eliminate this tendency. This is not desirable for crystal glass, where perfect transparency is important.

If the SiO content is less than 50.0% by weight, then the glass mixture is unsuitable in terms of chemical durability, but if the SiO content exceeds 60.0% by weight, then the melting point 2 of the glass mixture and the density of the glass must be increased. the mixture is reduced. Although BaO and CaO can be included together under alkaline earth metals, the BaO content must be higher to ensure high density and high refractive index. When RO (BaO + CaO) is less than 0% by weight, a cannon density value of 2.90 g / cm or more cannot be achieved. If the RO (BaO + CaO) is more than 20.0% by weight, although the viscosity of the glass composition at a higher temperature decreases, the viscosity in the working range is high and the workability is impaired. In addition, the corrosion of the furnace material is noticeable, making it difficult to melt the glass mixture.

The alkaline components R 4 O (K 4 O + Na O + Li O) are used to lower the melting point. If the R ^O content exceeds 20% by weight, then, although the melt is improved, the chemical durability of the glass composition is reduced and the corrosion of the refractory increases. K 2 O is effective and important in controlling the staining caused by Fe ions, which are an impurity in the glass. The content of K O is 2

4% to 14% by weight. ^At 2 ° 3 ^e required to affect the decrease in melting temperature. ^Li 2 ° has a great effect on lowering the melting temperature even in small quantities and is sufficient to contain it in an amount of 1.0% by weight. or less, also because it is expensive.

ZnO is effective to increase chemical durability without reducing the hardness of the glass, adjusts the viscosity 5 temperature curve and facilitates processability. Sufficient amounts for addition are 5.0% to 15.0% by weight.

Even if they are used as NaNO (sodium nitrate) or BaO 3 2 (barium peroxide) as an oxidizing agent, then Sb O (antimony dioxide 2) or As O (arsenic acid) as a defoaming agent, the reason why both are used that they counteract the formation of a yellowish TiO color. NaNO as oxidizing agent. 23 does not show an observable effect if its content is less than

1.0% by weight. but must be added in an amount of 1% to 5% by weight. In order to maximize the effect of color suppression it is necessary to add 4% by weight. NaNO. The use of BaO has no appreciable effect if its 3 ² content is less than 0.3% by weight. If the content exceeds 2.0% by weight, there is no appreciable improvement in performance. Sb O and As O as 2 3 2 3 anti-foaming agents have no effect on color suppression or anti-foaming effects as long as their content is less than 0.2% by weight.

Addition of 1.0% by weight. is sufficient. Even when the mixture

NaNO with Sb O or As O commonly used as a blowing agent to improve the glass defoaming, in the present invention, in order to utilize the oxygen produced at high temperatures as an oxidizing agent, an amount of the mixture greater than 0.05 to 0.5 is added. % wt. (depending on the batch of glass mixture), which is the amount that is added to conventional glasses. The ratio of addition of oxidizing agent and antifoaming agent is basically determined from the reaction equation between them. The reaction equation is exemplified by NaNO and As O.

2 3

At low temperature:

NaNO -> 2 Na + 4 NO +0

2 2 2

As 0 +0-> As 0

3 2 2 5

At high temperature:

As O-> As 0 + 0, 2 5 2 3 2

Accordingly, NaNO and As O should be ingested at a ratio of 4: 1 mole%.

Since the oxidizing agent and the antifoam are added to achieve simultaneous clarification and suppression of the yellow coloration that results from TiO when the amount is increased

The addition of an oxidizing agent and a defoaming agent has to be increased. Although this depends on atmospheric melting conditions, a suitable addition of antifoam agent is

1/3 of 5 to 1/20 of the amount of TiO molar.

Since BO is also effective in reducing the melting point in small amounts without increasing the coefficient of thermal expansion, it is added in an amount of 2.0% by weight. or less.

Although ZrO is added to increase the chemical stability, 2 because it increases the hardness of the glass, its use in crystal glass, which is mostly processed by grinding or polishing, is not desirable and its content should be kept to a minimum.

In another aspect, the present invention provides a method of making a lead-free crystal glass composition comprising SiO 2.

TiO to increase refractive index and light scattering, BaO to increase 2 density and refractive index, and K 0 to suppress staining with Fe ions as an essential component, include the step of adding to a batch of glass blend consisting of 50 to 60 weight percent SiO ^4. percent by weight K 0, 10 to 20 percent by weight BaO and 2 to 10 percent by weight TiO, NaSb (OH) in an amount of 0.5 to 26%

2.0 weight percent to eliminate the formation of color and foaming resulting from 3 to 10 weight percent TiO.

In this case, to compensate for the reduction due to the BaO content, the batch composition also preferably contains CaO at high temperature viscosities which is and the CaO content is 10 to 20 percent by weight, with a BaO / CaO ratio> 2.

NaSb (OH) (sodium antimonate) added in an amount of 0.5 to 2.0 6 percent by weight as an additive that serves as an oxidizing agent, at high temperatures the reagent and antifoam react as follows

NaSb (OH) -> Sb 0 + Na 0 + 6 H 0

2 5 2 _J 2 and Sb 0 (antimony oxide) are further decomposed as follows

Sb O-> Sb O +0 2 5 2 3 2

Sb O (antimony trioxide) has a blackening (antifoam) effect when O 2 3 2 (oxygen) acts as an oxidizing agent for ferrous ions and thus has a bleaching effect.

Since NaSb (OH) (antifoam) necessity (sodium antimonate) has both blackening and oxidizing effects, the use of NaSb (OH) eliminates the use of an oxidizing agent such as Sb O (antimony trioxide) or As ^ O ^ (arsenic acid). Next is the use

NaSb (OH) - also advantageous in that low evaporation losses occur.

An appropriate amount to the amount of NaSb (OH), 1.6 dose relative to glass 100) which is added (0.5 to 2.0 percent by weight added. If the amount added is less than 0.5% by weight, this results in however, if the amount added is more than 2.0 wt.%, then the defoaming is sufficient, because of the large amount of Sb, the glass becomes yellow.

The color tinting of the glass depends on the amount of glazed Sb O 2 3 rather than on the added amount of NaSb (OH) itself. By way of example, there is a 6 glass permeability curve to which NaSb (OH) was added in 6 amounts of 0.5% by weight. (0.3 wt.% As Sb 0), the same as the glass permeability curve 23, to which NaNO 2 (sodium nitrate) was added in an amount of 1.5 wt.%. and Sb 0 (antimony dioxide) in an amount of 0.3% 23 wt.

Due to the described action of the components, it is possible to obtain a glass composition which satisfactorily meets the requirements for crystal glass, which are:

1. The density, as a physical figure which represents massiveness, is 2,90 g / cm or more;

2. A refractive index Nd of 1.55 or greater;

3. Abbé's number as the physical figure representing the variance is 47 or less;

about

4. The glass mixture melts readily at a lower temperature of 1350 ° C to 0 ° C

1450 C;

, -7 o

5. a coefficient of thermal expansion of less than 100 x 10 / C, taking into account that the glass mixture is often used for cookware; and

6. the glass mixture has sufficient translucency as crystal glass.

It should be noted that it is naturally possible to add a coloring agent such as chromium trioxide in small amounts to produce colored crystal glass.

As described in the present invention since

TiO 2 is used as a raw material instead of Pbo and NaNO or BaO as an oxidizing agent and Sb 0 or As O as a defoaming agent 2 3 2 3 are used and added individually in a suitable amount or otherwise with NaSb (OH) & (sodium antimonate) which it serves as an oxidizing and antifoaming agent, adds to suppress the formation of a yellowish TiO color, giving a crystal glass having a density, refractive index and scattering value equal to or greater than conventional lead glass, even if it does not contain lead at all.

Furthermore, the raw materials are comparatively inexpensive and can be melted at a comparatively low temperature, and thus the glass mixture can be produced economically.

When NaSb (OH) (sodium antimonate) is added, since it has both antifoaming and oxidizing effects, it is not necessary to add an additional oxidizing agent such as Sb O or 2 3

As 0. Furthermore, NaSb (OH) is also advantageous in that there is little evaporation loss.

Taking into account that limiting lead is important not only to solve the problem of dissolving from glass, but also to the processing environment and environmental pollution caused by dust and fumes released in various steps from not mixing raw materials to furnace melting, which does not contain highly toxic lead, even more pronounced.

Said objects, features and advantages of the present invention will be apparent from the following description and the appended claims, together with the accompanying drawings, in which particles or elements are indicated by reference.

Brief description of the picture

Fig. 1 is a diagram illustrating light transmission curves where NaNO (sodium nitrate) was used as an oxidizing agent; and 3

Sb O (antimony dioxide) as antifoam agent in the mixture, each 2 3, separately and none.

DETAILED DESCRIPTION OF THE INVENTION

Detailed description of preferred embodiments

The samples of Example 1 to Example 10 were mixed to obtain a glass composition of the composition shown in the Table

2, and the mixtures were individually placed in platinum containers and fused for 6 hours at 1375 ° C in an electric furnace. Then, the vessels were removed and the molten glass was blown onto a steel plate and gradually cooled in an annealing furnace. They were then measured and the fracture, abbe number and thermal expansion coefficient were determined for each sample. The measurement results are shown in Table 2. In Table 2, Pr. 1 to Pr. 2 denotes Example 1 to Example 10.

Table 2 also shows the color tones obtained by the cut off sample density, index of glass blends. Where an oxidizing and antifoaming agent such as in Examples 1 to 3 is not used at the same time, the glass mixture undesirable coloration (yellow-brown).

It should be noted that conventional lead-containing crystal glasses have a density of 2.95 g / cm to 3.00 g / cm, a refractive index Nd of 1.555 to 1.565, an Abbé number of 45 to 47, and a coefficient of thermal expansion of 96 to 100 x 10 / C.

Table 2

Components and physical data Pr. 1 Pr. 2 Pr. 3 Pr. 4 Pr. 5 Pr. 6 Pr. 7 Pr. 8 Pr. 9 Pr. 10 You are about, 54.95 54.6 51,15 50.1 55.5 55.2 55 52 52 52 CaO 4 3.5 5 3 1.5 1.5 4.8 5 2 BaO 12 12.5 14 14.5 13 13.3 14 10.5 12 13 To 0 3 3.5 3 3 6 9.5 6.5 4 ABOUT ABOUT K, 0 9 10 11 12.5 7 5 4.5 10 11 3 Li 0 0.5 0.5 0.5 0.5 TiO. 7.5 7 5 7 6, 5 5 7.5 8 9 7.5 ZnO 7.5 8 7, 5 7 9 9 6 8 8 9 ZrO, 1 1 1 B-0. 1.25 1 1.5 1 1 T. 1 2 1, δ 2 Sb-Oj 0.5 0, 65 0, 5 0.5 0.8 0.5 1 · As.O. 0.5 0.8 NaNO, * 1 1.5 1.5 2.5 4.5 BaO. * 1 0, 5 3 NaSb (OH) ₆ * 1 0.85 Density (g / cm ³ ) 2,885 2,908 2,951 2,955 2,902 2,906 2,917 2,907 2,906 2,944 Refractive index Nd 1,589 1.59 1,588 1, 601 1,532 1,577 1,536 1,595 1,591 1,591 Abbe number 46, 5 46.8 48.2 46, 5 47 47 46.4 45.6 44.5 46 coefficient * 2 (x10'7'C) 92.6 97 101.4 105.5 94.3 99.5 92 97 104 £ 98.1 Color tone * 3 from. h. bw bw good good good good good good good

* 1: The amount of NaNO ^, ^ ^and ^ BaO ^e ^ ° NASBA (OH) is the amount of addition to the batch, with the amount of the glass component of glass 100 as included in and O, BaO and Sb and O and O.

2 2 3 * 2: Coefficient - thermal expansion coefficient.

* 3: The color tone represents the color tone of the glass mixture. The concept of ž. h. in the color tone line the abbreviation is yellow-brown ”.

The invention is fully described herein, and it will be apparent to those skilled in the art that many changes and modifications can be made without departing from the scope of the invention as described.

Industrial usability

The glass compositions of the present invention can be used to produce lead-free crystal glass.

? t 1029 - 9?

Claims (4)

A method for producing a lead-free crystal glass composition comprising SiO2, T1O2 for increasing the refractive index and light scattering, BaO for increasing the density and refractive index, and K2O for suppressing the coloration of Fe ions as constituents, which consists of 50 to 60 weight percent SiO2, 4 to 14 weight percent K2O, 10 to 20 weight percent BaO, and 3 to 10 weight percent TiO2, adds 1.0 to 5.0 weight percent NaNOg to suppress color development, which results from 3 to 10 weight percent TiO 2 and one of Sb 2 O 3 and AS 2 O 3 simultaneously is added in an amount of 0.2 to 1.0 weight percent as antifoam. 2. The method of manufacturing a lead-free crystal glass composition which includes SiO 2, T1O2 to increase the refractive index and dispersion of light, BaO for increasing the density and the refractive index and K ₂ 0 to suppress the color of Fe ions as the essential components, characterized in that the dose of a mixture consisting of 50 to 60 percent hmotnostmých SiO2, 4 to 14 percent by weight of K2O, 10 to 20 percent hmotnostmých BaO and 3 to 10 percent by weight of Ti0 _2, BaO ₂ is added in an amount of 0.3 to 2.0 percent by weight of the suppressing the coloration resulting from 3 to 10 percent by weight TiO2 and one of Sb2Og and AS2O3 simultaneously being added in an amount of 0.2 to 1.0 percent by weight as antifoam. 3. The method of manufacturing a lead-free crystal glass composition which comprises S1O2, T1O2 to increase the refractive index and dispersion of light, BaO for increasing the density and the refractive index and K ₂ 0 to suppress the color of Fe ions as the essential components, characterized in that the dose of a mixture consisting of 50 to 60 percent hmotnostmých SiO2, 4 to 14 percent by weight of K ₂ 0, 10 to 20 percent hmotnostmých BaO and 3 to 10 percent by weight of T1O2, added NASBA (OH) g in an amount of 0.5 to 2.0 percent by weight to suppress coloration resulting from 3 to 10 percent by weight of T102. A method for producing a lead-free crystal glass composition according to any one of claims 1, 2 or 3, characterized in that the batch composition comprises CaO to compensate for the high temperature viscosity reduction resulting from BaO and the BaO and CaO content is adjusted to 10 to 20 percent by weight, with a BaO / CaO ratio of 2;