KR100824934B1 - Gray soda lime glass composition - Google Patents

Abstract

A gray soda lime glass composition is provided to be easily manufactured even in a melting process of ordinary soda lime glass, and effectively control an increase in visible light transmittance even without using a colorant such as Ni or Cr. A gray soda lime glass composition includes a soda lime mother glass and a colorant. The soda lime mother glass comprises 65-75wt% of SiO2, 0.3-3.0wt% of Al2O3, 10-18wt% of Na2O+K2O, 5-15wt% of CaO, and 1-7wt% of MgO. The colorant contains 0.75-1.1wt% of Fe2O3, 0.019-0.035wt% of CoO, 0.001-0.005wt% of Se, 0.002-0.05wt% of CuO, and 0-0.5wt% of TiO2, based on 100wt% of the mother glass. The composition has a main wavelength of 480-580 nm and an excitation purity of 0.1-10%.

Description

Gray soda lime glass composition

The present invention relates to a gray soda lime glass composition (colored glass) characterized by low visible light transmittance, ultraviolet light transmittance and solar light transmittance.

The use of the colored glass is not particularly limited, but may be applied to a privacy glass or sunroof and a building glass at the rear of the vehicle. Since the colored glass has a lower visible light transmittance than general soda lime glass, visibility of the interior of the vehicle can be reduced, and the heat absorption into the vehicle can be reduced due to the low total solar transmittance. In addition, the low UV transmittance may prevent fabric damage, discoloration, or decomposition of the internal materials by ultraviolet rays.

The color of the colored glass can be realized through the incorporation of various colorants, and representative colorants used in gray colored glass include iron (Fe), cobalt (Co), selenium (Se), and the like, and manganese (Mn). ), Nickel (Ni), copper (Cu), chromium (Cr), titanium (Ti), cerium (Ce) and the like can be used. These coloring elements have inherent coloring effects, thereby showing intrinsic coloring properties in glass. This color development is due to the phenomenon that each color element absorbs visible light at a specific measurement wavelength, and the desired color and transmittance can be designed through an appropriate combination of color components.

The difference between the color intensity of the various colorants and the color region determines the final color of the glass, and gray glass having a privacy function can be produced through proper adjustment of each element. Various compositions of such gray soda lime glass are known and can be broadly divided into the case where Fe, Co, and Se are made of the base colorant and the case of adding other elements.

U.S. Patent No. 4,873,206 discloses a glass composition comprising 0.6-1.0 wt% total Fe ₂ O ₃ , 100-200 ppm CoO, 50-200 ppm Se and free of Ni and Cr. However, the composition is not suitable to give a privacy blocking function, which is one of the important functions of the gray glass applied to the sunroof with a visible light transmittance of 25 to 30% level based on the glass thickness of 4mm.

In addition, Korean Patent Publication No. 1992-0007944 (U.S. Patent No. 5,393,593) discloses a glass composition including a total Fe ₂ O ₃ 1.0 ~ 1.7 wt%, CoO 100 ~ 200ppm, Se 10 ~ 50ppm. However, since the composition of Fe ²⁺ (FeO) is inevitably increased due to the high total Fe ₂ O ₃ content, the thermal conductivity drops sharply, resulting in an increase in fuel consumption and a decrease in melting quality due to a decrease in temperature at the bottom of the furnace. There is such a problem.

As a similar patent, Korean Patent Publication No. 10-027250 (U.S. Patent No. 5,352,640) has a total Fe ₂ O ₃ 1.4 ~ 4% by weight, CoO = 200ppm, Se = 50ppm, CoO + Se + Cr ₂ O ₃ = 0.24% by weight A glass composition comprising is disclosed. However, the composition also causes an increase in Fe ²⁺ due to the high total Fe ₂ O ₃ content as described above, resulting in a lower thermal conductivity and increased fuel cost, a lower furnace temperature, a lower melt quality. In addition, the Cr used in the composition is known as a poorly soluble material, and as the amount of use increases, cosmetic melts may occur, causing uneven color.

Korean Patent Registration 10-029539 (U.S. Patent No. 5,308,805) discloses a glass composition including a total Fe ₂ O ₃ 1.3 to 2% by weight, CoO 200 to 400ppm, Se 2 to 30ppm content, but also a total Fe ₂ O _{3 High} content and contains Ni. When Ni is mixed, it may be present as NiS during melting of glass, and NiS is known to cause breakage of glass due to volume expansion in the glass strengthening process. Gray soda-lime glass is used for automobiles, and since it is necessarily strengthened, the use of Ni may cause a problem of increasing glass failure failure.

The object of the present invention is to improve the melt load problem caused by the high iron content of the prior art as described above, can be easily produced in the melting process of general soda-lime glass, and colorants such as Ni or Cr By effectively controlling the increase in visible light transmittance without using satisfactory privacy performance, to provide a glass composition that can lower the solar transmittance and ultraviolet transmittance at the same time.

The present invention relates to a total Fe ₂ O ₃ 0.75 to 1.1% by weight, CoO 0.019 to 0.035% by weight, Se 0.001 to 0.005% by weight, CuO 0.002 to 0.05% by weight, and TiO ₂ 0 to 0.5% by weight relative to 100% by weight of the mother glass It relates to a gray soda lime glass composition comprising a coloring agent containing.

The colorant composition of the present invention as described above is specified by the following.

Iron (Fe) may be included as an impurity in the main and secondary raw materials of the glass, and may be present in the glass at a level of 0.1 to 0.2% by weight without additional input in normal commercial production. Most colored glass uses iron oxide (Fe ₂ O ₃ ) as the raw material to adjust the desired transmittance and color by adding iron, and the iron oxide added during the melting of the glass is Fe ³⁺ and Fe ²⁺ May exist. Fe ³⁺ ions have a weak absorption in the visible light region of 410 ~ 440 nm, and a strong absorption edge in the vicinity of ultraviolet light around 380 nm, due to this property, the more Fe ³⁺ present, the glass becomes pale yellow. Will be displayed. In addition, Fe ²⁺ ions are known to absorb infrared rays because there is a strong absorption band around 1050 nm, the more the Fe ²⁺ content, the color of the glass changes to blue. The presence ratio of Fe ²⁺ / Fe ³⁺ has an important influence not only on the color of the glass but also on the glass manufacturing process.

Melting of the batch of glass stock proceeds in the furnace, the main heat source being radiant infrared light supplied through the combustion of the gas burner. Most of the heat transfer mechanism from the heat source to the glass raw material is transmitted through radiation, and the amount of heat required for melting is changed depending on how efficiently the heat generated through gas combustion is transferred to the raw material batch. This radiant heat corresponds to infrared radiation, which supplies heat to the glass melt surface and into the glass melt. The proportion of Fe ²⁺ and Fe ³⁺ in Fe ₂ O ₃ varies depending on the production process, but the content of Fe ²⁺ (FeO) in the total iron content is controlled at a level of 10-30 wt%, usually 20 wt% It is produced at a level. Therefore, as the Fe ₂ O ₃ content contained in the glass melt increases, the Fe ²⁺ content also increases proportionally. However, as mentioned above, the absorption stage of Fe ²⁺ ions includes an infrared region, which serves to block radiant heat that must be transferred to the glass melt. “Colour generation and control in glass; CR Bamford; With reference to glass science and technology 2 ", infrared radiation emitted from gas burners is said to have the greatest effect of heat transfer mechanisms at the glass melting temperature. Major factors affecting thermal conductivity in the infrared region. The refractive index of the glass, the temperature of the glass, and the infrared absorption constant of the glass are closely related to the iron content in the glass melt. It is said to be at a quarter level, which is due to the fact that amber glass has a higher iron content than ordinary transparent glass.

In addition, "Chemical approach to glass; Milos B. Volf, 356 page" contains: In the case of glass containing iron, infrared radiation is absorbed by Fe ²⁺ to generate a thermal gradient depending on the glass melt depth. The temperature deviation caused by this thermal cutoff phenomenon was measured, and the following experimental formula was published.

t = t _o (1-Aτ ⁿ )

A = 0.0462 + 0.00985 Fe ₂ O ₃

n = 0.9-0.7 exp (-1.8 Fe ₂ O ₃ )

τ = 2.54 H

t = temperature (° C) of the glass interface located at depth H on the glass surface

t _o = temperature of the glass surface (° C)

As can be seen from the above formula, as the Fe ₂ O ₃ content increases, the temperature of the lower part of the glass melt decreases rapidly.In actual production, it may be interfered by convection in the melting furnace, but the total Fe ₂ O ₃ content increases. As a result, the temperature decrease was found to be very rapid.

As the iron content in the glass melt increases, the amount of Fe ²⁺ ions increases proportionally, and a decrease in thermal conductivity due to infrared absorption of Fe ²⁺ is inevitable. The effect of this reduction in thermal conductivity can be manifested in the use of more combustion gases than necessary and the temperature reduction of the glass melt. In addition to the cost loss problem, the increase in the use of the combustion gas may adversely affect the environment due to the increase in the exhaust gas generated. In addition, the temperature decrease of the glass melt due to the decrease in thermal conductivity may become more severe toward the bottom of the melting furnace, which is due to the increase in viscosity due to the decrease in the glass melt temperature, and the weakening of the convection flow is caused by defoaming or homogenization. The overall glass melting process can be aggravated overall, and the problems of this melting process are very likely to result in reduced production yields. Therefore, the present invention solves the problem of the melting process as described above, including a lower content of total Fe ₂ O ₃ than the conventional gray soda lime glass composition.

The total Fe ₂ O ₃ content of the present invention is 0.75 to 1.1 wt%. When the content is less than 0.75% by weight, it is difficult to perform the privacy protection function, which is one of the most important characteristics of the gray soda lime glass composition due to the increase in visible light transmittance, and when the content exceeds 1.1% by weight, an increase in the Fe ²⁺ content is inevitable. This may cause a problem that increases the melt load. It is more preferable that the total Fe ₂ O ₃ content of 0.81 to 0.99% by weight, and most preferably, the total Fe ₂ O ₃ to 0.89 to 0.98% by weight, can reduce the melt load and perform personal privacy protection. Include.

In addition, the content of Fe ²⁺ (FeO) (reduction rate: FeO / total Fe ₂ O ₃ ) is preferably 10 to 30% by weight of the total Fe ₂ O ₃ content. If the Fe ²⁺ content is less than 10% by weight, the visible light transmittance is increased and the oxidation probability of Se is increased, so that there is a problem in that the coloring of Se is halved. In addition, when the Fe ²⁺ content is more than 30% by weight, the clarification effect of the clarifier Na ₂ SO ₄ is reduced, and the volatilization amount of Se may increase, which may cause a problem in that a proper amount of Se cannot be left. In addition, there may be a problem of reducing the thermal conductivity in the melting process according to the increase of Fe ²⁺ , temperature reduction of the bottom of the melting furnace, quality degradation may be caused. It is more preferable that the content of Fe ²⁺ is 15 to 25% by weight, and the most preferable Fe ²⁺ content is 18 to 24% by weight, in order to be suitable for Se coloring and to reduce thermal conductivity problems.

Cobalt (Co) is supplied to the batch in the form of cobalt oxide and has absorption edges near 530, 590, and 645 nm in the presence of Co ²⁺ . Under the influence of these absorption stages, cobalt colors the glass with a strong blue color.

The content of CoO of the present invention is 0.019 to 0.035% by weight. The term ppm used in the present invention is intended to indicate the weight percent 100ppm means 0.01% by weight.

If the content of CoO is less than 0.019% by weight, a problem of increasing visible light transmittance occurs, which may reduce personal privacy, an important characteristic of the gray soda lime glass composition. In addition, when the content exceeds 0.035% by weight, a blue tint appears strongly on the glass, and an increase in the amount of Se input is required to make it gray. However, when the amount of Se input increases, visible light transmittance decreases significantly and manufacturing costs increase with increasing Se usage. It is more desirable to manage the CoO content between 0.02 and 0.03% by weight in order to effectively reduce the visible light transmittance and to balance the blue tint. The most preferable content of CoO is 0.021 to 0.027 wt%.

The selenium (Se) shows a difference in color development behavior depending on the oxidation / reduction state in the glass, and the absorption stage is present at 480 ~ 490 nm when present as Se element and when combined with FeSe. In this case it is known to color the glass red / brown.

The content of Se of the present invention is 0.001 to 0.005% by weight. If the content is less than 0.001% by weight, the glass appears to have a strong blue tint, and if the content exceeds 0.005% by weight, the color of the glass is close to bronze. In both cases, the problem of not being able to maintain grayscale and maintaining visible light transmittance with privacy protection may arise. In order to maintain the color tone and privacy function, the Se content is more preferably 0.0014 to 0.0045% by weight, most preferably 0.0024 to 0.0038% by weight.

Copper (Cu) is supplied to the glass in the form of copper oxide, and Cu ²⁺ ions have an absorption edge at 450 to 500 nm. It is known that the glass is colored greenish green under the influence of this absorption stage.

The content of CuO of the present invention is 0.002 to 0.05% by weight. If the content is less than 0.002% by weight, the visible light transmittance may be increased by 20% (based on the glass thickness of 4mm), which is the optimal visible light transmittance level of gray soda-lime glass, which may cause a problem of reducing the privacy barrier function. In this case, the gray scale of the glass cannot be maintained, and further adjustment of CoO and Se is required. It is more preferable that the content of CuO is 0.015 to 0.045% by weight in order to maintain privacy and to avoid additional colorant input. Most preferably, it is 0.019 to 0.041 weight%.

In the case of TiO ₂ is not an essential component, but may be optionally added for controlling the UV transmittance and visible light transmittance. If the content of TiO ₂ is more than 0.5% by weight, the color tone may change, so the content should be adjusted to less than that.

On the other hand, it is preferable to use the colorant within the content range with respect to 100% by weight of the mother glass, it is preferable that the main constituents of the mother glass has a composition range of the following Table 1.

SiO ₂ serves as a network forming agent for forming the basic structure of the glass, when the content is less than 65% by weight, there is a problem in the durability of the glass, and when the content exceeds 75% by weight, There is a disadvantage that the meltability is lowered.

Al ₂ O ₃ is a component that increases the high temperature viscosity of the glass and improves the durability of the glass when a small amount is added, and when the content is less than 0.3% by weight, Al ₂ O ₃ may be vulnerable to chemical resistance and water resistance, and exceeds 3% by weight. If included, there is a problem that the melt load increases with increasing high temperature viscosity.

Na ₂ O and K ₂ O are flux components that promote the melting of glass raw materials. If the sum of the two components is less than 10% by weight, the melt quality may decrease due to an increase in the amount of cosmetic melts. If it exceeds the problem that the chemical resistance degradation occurs.

CaO and MgO help to melt the raw materials and reinforce the weather resistance of the glass structure. If the CaO content is less than 5% by weight may cause a decrease in durability, if it exceeds 15% by weight may increase the crystallization tendency may adversely affect product quality. In addition, in the case of MgO less than 1% by weight, the above-mentioned effect is reduced, and when it exceeds 7% by weight, an increase in crystallization tendency causes an increase in crystal defects.

In actual production, forget-me-not (Na ₂ SO ₄ ) can be used to improve melt quality such as bubble removal, and the content of SO ₃ gas remaining in the glass during the melting process is generally controlled to 0.01 to 1.0% by weight. .

Gray soda-lime glass manufactured in the above composition range may be applied as a disc for automobile safety glass, and may be applied to building window glass. In automotive glass, it may be applied to a sun roof or a rear window, but its use is not limited thereto. In order to have a privacy protection function, which is one of the important characteristics of the gray soda lime glass composition, the following optical properties are required.

Based on the glass thickness of 4 mm, the visible light transmittance T _vis is preferably less than 20%, the solar light transmittance T _sol is 26% or less, and the ultraviolet light transmittance T _uv is preferably less than 10%.

If the visible light transmittance increases by more than 20% due to the problem of colorant content control, the applicability may be limited due to the deterioration of the privacy barrier, which is the main characteristic of the gray soda lime glass, and the sun roof or the rear window of the automobile glass. This can be particularly problematic where privacy protection is required.

Ultraviolet rays have a great influence on the aging of interior materials, so it is necessary to manage the transmittance to less than 10%.

Also having the transmittance range as described above, the color tone of the glass should be adjusted as follows. The colorant content should be adjusted so that the dominant wavelength range (D _w ) is 480 to 580 nm and the stimulation purity (P _e ) is 0.1 to 10%. If the adjustment fails within this range, blue and red ) Hue may be strongly developed, and gray color cannot be maintained.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are provided only to assist in understanding the present invention, but the present invention is not limited thereto.

Examples 1 to 6 and Comparative Examples 1 to 3

Sample glass preparation for the evaluation of physical properties in the present invention was prepared through a gas furnace and an electric furnace, after quenching the raw material batch weighed on a basis of 500 g at 1450 ℃ for 1 hour to recover the glass powder, repeated re-melting twice To increase the homogeneity of the sample.

The raw materials used were silica sand, feldspar, limestone, dolomite, soda ash, forget-me-not, iron oxide, cobalt oxide, selenium, copper oxide, titanium oxide, and the like, and the mixture was adjusted to obtain the target composition mentioned in the following Examples / Comparative Examples. Glass batches were melted using a gas / electric furnace. In the glass composition, the parent glass composition excluding the colorant contained 71.2% SiO ₂ , 0.95% Al ₂ O ₃ , Ca 9.8%, MgO 3.8%, Na ₂ O 13.9%, K ₂ O 0.15%, and SO ₃ 0.2 by weight. A soda lime glass composition consisting of% was used.

The colorant content mentioned in Examples / Comparative Examples was added based on 100% by weight of the mother glass composition, and the glass thus prepared was processed to 4 mm thickness after the sample glass was cast using a graphite plate to evaluate physical properties.

Chemical composition analysis of the glass composition was performed using a 3370 X-ray fluorescence spectrometer (XRF) from Rigaku.

Optical properties were measured using the following equipment.

The visible light transmittance was measured by a 1931 CIE Yxy / 2 degree field of view (source A) using a HUNTER LAB colorimeter.

Solar transmittance and UV transmittance were measured according to KSL 2514 and ISO 9050 using VARIAN Cary-500 spcetrophotometer.

The dominant wavelength and color purity were measured in 1931 CIE Yxy / 2 degree field of view (light source C) using HUNTER LAB colorimeter.

In the case of residual bubbles, the bubbles inside the glass were observed under a microscope after melting at 1450 ° C. for 1 hour, and the number of bubbles present at the same weight was evaluated.

The difference between the glass glass melt surface and the internal temperature was calculated using the t = to (1-Aτ ⁿ ) equation described above to evaluate the deterioration of the melting process due to the temperature decrease of the glass melt due to the reduced thermal conductivity. The surface temperature of the glass melt was assumed to be 1600 ° C. That is, it is the value which shows the difference between the glass melt surface temperature according to the iron content of an Example and a comparative example in these conditions, and the internal temperature of the glass melt of 1 m depth.

The composition components and measured physical property values of each glass are described in Table 2 below.

Visible light transmittance (T _vis ), solar light transmittance (T _sol ), ultraviolet light transmittance (T _uv ), dominant wavelength (D _w ) of glass specimens prepared according to Examples 1 to 6 and Comparative Examples 1 to 3 described in Table 1 , And stimulation purity (P _e ) were measured in the manner described above. Comparative Examples 1 and 2 are representative compositions of gray soda-lime glass prepared by the prior art, and Comparative Example 3 is a case where the total Fe ₂ O ₃ , CoO and Se content in the composition range of the present invention is satisfied but CuO is not used. .

As shown in Table 1, in the case of the glass prepared in the composition of Examples 1 to 6, the total Fe ₂ O ₃ range was also maintained at 1.1 wt% or less, and the dominant wavelength and color purity were also satisfied by adjusting the colorant. Doing. In addition, by maintaining the visible light transmittance of less than 20%, it was confirmed that the privacy blocking function, which is an important characteristic of grayscale soda lime glass, is also maintained.

Comparative Examples 1 and 2 were gray soda-lime glasses prepared by the prior art, the iron content was maintained at a high level, it was confirmed that the same visible light transmittance as in Examples 1 to 6. In view of these characteristics, the privacy barrier function is judged to be equal, but the number of residual bubbles is increased according to the same melting temperature / melting time, and this problem is considered to be due to the decrease in thermal conductivity as described above. .

In addition, as can be seen in Comparative Examples 1 and 2, the temperature difference between the glass melt surface and the inside of iron increases as the level is 205 to 209 ° C. Such a decrease in temperature of the glass melt may cause problems such as bubble defects and unmelted defects, which may worsen the glass melting process. Therefore, in order to overcome the side effects due to the decrease in temperature, it is necessary to increase fuel consumption, which leads to an increase in manufacturing cost and an increase in gas emissions.

In Comparative Example 3, a similar colorant content as in Example was added, but CuO was not used. In this case, the number of residual bubbles was similar, but the visible light transmittance tended to increase to 23%, which is applied to automobile glass and building glass because the privacy blocking function, which is a key characteristic of gray soda lime glass, is reduced. This may be limiting.

The present invention was able to develop a gray soda lime glass composition without increasing the visible light transmittance by reducing the total total Fe ₂ O ₃ content and using a new colorant CuO. Through this development, the thermal conductivity due to the high iron content, which was a problem in the prior art, alleviated the problem of melting load, thereby developing a composition that is easier to produce in the existing glass melting furnace.

Claims (5)

Soda lime including 65 to 75 wt% SiO ₂ , 0.3 to 3.0 wt% Al ₂ O ₃ , 10 to 18 wt% Na ₂ O + K ₂ O, 5 to 15 wt% CaO, and 1 to 7 wt% MgO Mother glass; And Total Fe ₂ O ₃ 0.75 to 1.1% by weight, CoO 0.019 to 0.035% by weight, Se 0.001 to 0.005% by weight, CuO 0.002 to 0.05% by weight, and TiO ₂ 0 to 0.5% by weight relative to 100% by weight of the mother glass Coloring agent; Gray soda lime glass composition comprising a. The gray soda lime glass composition according to claim 1, wherein the content of FeO in the total Fe ₂ O ₃ is 10 to 30% by weight. delete The gray soda lime glass composition according to claim 1 or 2, wherein the visible light transmittance is 20% or less, the solar light transmittance is 26% or less, and the ultraviolet transmittance is 10% or less based on a glass thickness of 4 mm. The gray soda-lime glass composition according to claim 1 or 2, wherein the dominant wavelength is 480 to 580 nm and the stimulation purity is 0.1 to 10%.