JP2011236114A - Lead-free glass for forming barrier rib - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barrier rib material where chipping due to an impact hardly occurs when it is used in a plasma display in comparison with the conventional material.SOLUTION: In this lead-free glass for forming a barrier rib, the nominal composition ratio in mol% expression is such that the sum total of the contents of BO, SiOand AlOis 72% or more, the content of LiO is 5-19%, the molar ratio of KO/(LiO+NaO) is one or lower, and the Young's modulus at room temperature is 80 GPa or lower. As details of the glass composition, the content of BOis 20-55%, that of SiOis 10-50%, that of AlOis 4-20%, the sum total of the contents of one or more of LiO, NaO and KO is 5-20%, and the content of ZnO is 0-20%.

Description

  The present invention relates to a lead-free glass suitable for manufacturing a partition wall of a plasma display device (PDP).

PDP is a typical large-screen full-color display device.
The PDP is manufactured by sealing a front substrate used as a display surface and a rear substrate on which a large number of stripe-shaped or waffle-shaped barrier ribs are formed facing each other, and enclosing a discharge gas between the substrates.

In the front substrate, a plurality of display electrode pairs for generating surface discharge are formed on the front glass substrate, and these electrode pairs are covered with a transparent glass dielectric. The electrode pair usually comprises a transparent electrode such as ITO and a bus electrode formed on a part of the surface thereof. As the bus electrode, a silver electrode, a Cr—Cu—Cr electrode, or the like is used.
On the rear substrate, in addition to the electrodes, barrier ribs and phosphor layers are formed.

The glass (dielectric) that covers the electrode on the front substrate is formed by transferring a green sheet containing glass powder onto the electrode and baking it, or applying a paste containing glass powder on the electrode and baking it. Is done.
The glass used for the partition wall formed on the back substrate is required to be fired at a low temperature, to maintain a target shape after firing, and to be free from chipping due to vibration and impact.

  Furthermore, recently, attempts have been made to increase the number of pixels and increase the luminance in order to improve the image quality of plasma televisions. By increasing the number of pixels, the area of the pixels partitioned by the partition is reduced. If the structure of the partition is the same as the conventional structure, the opening of the screen becomes small and the screen becomes dark. Therefore, a device for reducing the width of the partition and keeping the size of the pixel is devised. Further, in order to increase the luminance, it is important to increase the area of the phosphor that emits light upon receiving ultraviolet rays, and in that case, a device for increasing the height of the partition walls has been made.

Japanese Patent No. 3696725

As described above, the partition wall of the plasma display is narrow and high in height, so that the conventional partition wall material is partially missing due to some impact in the process of assembling the panel or contact impact with the front substrate after the panel is formed. There was a risk of falling. If a part of the partition wall is dropped, there is a possibility of causing a pixel defect or crosstalk between cells. In order to prevent the partition wall from falling off, a material that does not easily crack due to impact is required. Regarding the ease of occurrence of this crack, the crack initiation load (hereinafter abbreviated as CIL), which will be described later, and the falling ball strength H / H ₀ were considered as indices.

Further, in order to make the material strong against impact, no strain is generated when stress is applied to the material. That is, a low Young's modulus (hereinafter sometimes referred to as E) is required. With respect to the partition wall material proposed in Patent Document 1, Young's modulus was measured, and a PDP glass substrate (PD200 manufactured by Asahi Glass Co., Ltd. having an α _A of 83 × 10 ⁻⁷ / ° C., hereinafter sometimes referred to as “conventional glass substrate”). .) The partition wall glass was baked to cover the entire surface of the glass substrate, and the falling ball strength H / H ₀ was measured. The CIL was 405 g / cm ² , the falling ball strength was 1.8, and the Young's modulus was 86 GPa.

H and H ₀ will be described in detail in Examples and the like of the present specification. H is the height when the glass substrate is broken by a falling ball test of a glass substrate in which a glass layer is formed of partition wall forming glass. , H ₀ is the height when the glass substrate is broken by a falling ball test of a glass substrate without a glass layer.

  An object of the present invention is to provide a barrier rib material that is less likely to be chipped off by impact when used in a plasma display as compared with a conventional material.

The present invention is for partition wall formation in which the total content of B ₂ O ₃ , SiO _2, and Al ₂ O ₃ is 72% or more, and the Young's modulus at room temperature is 85 GPa or less, expressed in mol% on an oxide basis. Lead-free glass.

In the present invention, the total content of B ₂ O ₃ , SiO _2, and Al ₂ O ₃ is 72% or more, Li ₂ O is 5 to 19% in terms of mol% based on oxide, and K ₂ It is a lead-free glass for barrier rib formation in which the molar ratio of O / (Li ₂ O + Na ₂ O) is 1 or less.

In order to solve the above-mentioned problems, it is necessary to make cracks difficult to occur in the partition wall material, and it was considered important to have high CIL and falling ball strength H / H ₀ values and low Young's modulus values. . As a result of intensive studies, each characteristic value has a correlation with the glass composition, and the composition range was defined.

According to the present invention, it is expected that a partition wall material having a high value of CIL and falling ball strength H / H _{0 and} a low value of Young's modulus can be provided, and the partition wall is hardly chipped.

The glass of the present invention is usually classified after pulverization and pulverized to be used for the partition walls.
In the case where the partition walls are produced using glass paste, the powdered glass of the present invention (hereinafter referred to as the glass powder of the present invention) is a ceramic filler such as SiO ₂ , Al ₂ O ₃ , ZrO _{2, and the} like. A pigment such as TiO ₂ is added and kneaded with the vehicle to form a glass paste. This glass paste is applied on the back substrate on which the dielectric layer is formed, and the shape of the partition is formed by a sandblasting method or a photosensitive method.
In addition, after the shape of the partition is formed, the back plate is typically fired at a temperature of 600 ° C. or lower.

  It is preferable that Ts of the glass of this invention is 610 degrees C or less. If it exceeds 610 ° C., the firing of the glass frit at a temperature of 600 ° C. or lower may reduce the fluidity of the glass frit, which may result in a partition that is not easily sintered and is easily chipped. More preferably, it is 600 degrees C or less.

E of the glass of the present invention is 85 GPa or less. If it exceeds 85 GPa, the impact cannot be sufficiently absorbed, and the partition walls may be damaged. It is preferable that it is 80 GPa or less. More preferably, it is 70 GPa or less. Although chipping of the partition is considered to occur by the electrode-covering glass layer of the partition walls and the front substrate being damaged by collision, impact E at this time partition wall due to collision equal to or less than 80GPa is sufficiently absorbed, it is considered to be scratch resistant Because. Typically, it is 70 GPa or less.

For example, E is measured as follows.
The slowly cooled glass is processed into a plate shape having a thickness of 10 mm, and E is measured according to JIS R 1602-1995 “Elastic Modulus Test Method of Fine Ceramics 5.3 Ultrasonic Pulse Method”.

Α of the glass of the present invention is preferably 80 × 10 ⁻⁷ / ° C. or less. When the partition wall is formed on the glass substrate as it exceeds 80 × 10 ⁻⁷ / ° C., the strength of the glass substrate decreases. More preferably, it is 75 × 10 ⁻⁷ / ° C. or less. More preferably, it is 71 * 10 < ^-7 > / degrees C or less. Moreover, (alpha) of the glass of this invention is 50 * 10 < ^-7 > / degreeC or more typically. If α is less than 50 × 10 ⁻⁷ / ° C., the stress generated by the difference between α of the glass substrate, that is, α ₀ becomes too large, and the substrate may be deformed or broken.

For example, α is measured as follows.
The annealed glass is processed into a cylindrical shape having a length of 20 mm and a diameter of 5 mm, and an average linear expansion coefficient α at 50 to 350 ° C. is measured using a thermal expansion meter TMA-8310 manufactured by Rigaku Corporation using quartz glass as a standard sample. .

The CIL of the glass of the present invention is preferably 450 g / cm ² or more. When CIL is less than 450 g / cm ² , cracks may easily occur when an impact is applied to the partition walls. More preferably, it is 600 g / cm ² or more.

CIL is measured, for example, as follows.
The molten glass is poured into a stainless steel mold and slowly cooled.
The slowly cooled glass is processed into a sheet glass, and one surface thereof is mirror-polished to obtain a glass test piece having a typical size of 50 mm × 50 mm and a thickness of 10 mm.
Using this glass test piece, using a Vickers hardness tester, a Vickers indenter is pushed into the surface of the glass test piece for 15 seconds in a glove box having a relative humidity of 35% or less, and the number of cracks is measured. The indentation load at that time was measured between 10 g and 1 kg, and the load with two cracks was measured.

The falling ball strength H / H ₀ of the glass of the present invention is preferably 2.5 or more. If H / H ₀ is less than 2.5, cracks may easily occur when an impact is applied to the partition walls. More preferably, it is 3.0 or more.

H / H ₀ is measured as follows.
Typically, a glass substrate having a size of 100 mm × 100 mm and a thickness of 1.8 mm is manufactured, placed on a water-resistant abrasive paper having a particle size of # 1500, and 45 g from the height of 3 cm on the upper surface of the glass substrate. Drop the stainless steel ball. When the glass substrate is not broken by the fall of the stainless steel ball, the drop height is increased by 5 mm and the stainless steel ball is dropped. The drop height is increased in steps of 5 mm until the glass substrate breaks, and the stainless steel ball is dropped.
Such glass substrate fracture test repeated five times, the average value of fracture height obtained and H _0.

H is an average value of breaking heights measured in the same manner as H ₀ for a glass substrate with a glass layer in which one surface of the glass substrate is coated with a glass for forming a partition wall having a thickness of 20 to 30 μm.
That is, the addition of placing on the waterproof abrasive paper in the same manner as H ₀ repeatedly measuring glass substrate destructive testing with the glass layer 5 times, resulting fracture height the surface being covered by glass for forming barrier ribs in the lower Let H be the average value.

The glass substrate with a glass layer is produced as follows.
100 g of partition wall forming glass powder was kneaded with 25 g of an organic vehicle in which 10% by mass of ethyl cellulose was dissolved in α-terpineol or the like to prepare a glass paste, and after firing on a glass substrate having a size of 100 mm × 100 mm Screen-printed uniformly to a film thickness of 20 μm and dried at 120 ° C. for 10 minutes. Thereafter, this glass substrate is heated to a softening temperature (Ts) or (Ts-50 ° C.) to Ts in the partition wall forming glass at a temperature rising rate of 10 ° C. per minute, and kept at that temperature for 30 minutes for firing. Then, a glass layer-forming glass layer having a thickness of 20 to 30 μm is formed on the glass substrate to obtain a glass substrate with a glass layer.

Next, the composition of the glass of the present invention will be described using a mole percentage display.
The preferable glass composition of the lead-free glass for forming a partition wall of the present invention is 20 to 55% B ₂ O ₃ , 10 to 50% SiO ₂ , 4 to 20% Al ₂ O ₃ , Li ₂ O, Na ₂ O and It contains any one or more of K ₂ O, the total content is 5 to 20%, and ZnO is 0 to 20%. The molar ratio of K ₂ O / (Li ₂ O + Na ₂ O) is 1 or less, and the molar ratio represented by (B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ) / (Li ₂ O + Na ₂ O + K ₂ O) is 4 .2 or more.

B ₂ O ₃ is a component having effects such as lowering Ts, lowering E, increasing CIL, and H / H ₀ when it contains a desired range, and is essential. If it is less than 20%, the above effects may be insufficient. Preferably it is 44% or more. If it exceeds 55%, the water resistance may decrease. Moreover, it becomes easy to phase-separate glass. When it is desired to increase the water resistance, it is preferably 50% or less, typically 48% or less.

SiO ₂ is a component having an effect such as forming a glass skeleton, reducing E, increasing CIL, and H / H ₀ , and is essential. If it is less than 10%, the glass may become unstable. Or ε may increase. Preferably it is 20% or more. If it exceeds 50%, Ts becomes high. Preferably it is 47% or less.

Al ₂ O ₃ is essential because it has effects such as reducing E and increasing water resistance. If it is 4% or less, the E of the glass tends to be high. Preferably it is 6% or more. If it exceeds 20%, Ts becomes high. Preferably it is 18% or less.
If the total content of B ₂ O ₃ , SiO _2, and Al ₂ O ₃ is 72% or more, the value of E is easily reduced.

Li ₂ O, Na ₂ O, and K ₂ O are components that lower Ts, and at least one of them is essential. If it is 5% or less, Ts may be high. More preferably, it is 8% or more. If it exceeds 20%, α may be too large. In particular, Li ₂ O is an essential component. Preferably it is 7.5% or more, More preferably, it is 10% or more. On the other hand, if it exceeds 19%, α may be too large.

It is preferable that the K ₂ O / (Li ₂ O + Na ₂ O) ratio is smaller than 1. If it exceeds 1, α may be too large, and H / H ₀ may be small.

  ZnO may have effects such as stabilizing the glass, lowering Ts, reducing α, and improving water resistance. In this case, ZnO may be contained in a range of 20% or less. When it contains, it is preferable to contain 2% or more. Crystallization that is greater than 20% can occur. The content of ZnO is preferably 15% or less.

As components that may be added for the purpose of adjusting α, Ts, chemical durability, glass stability, dielectric constant, etc., MgO, CaO, SrO, BaO, TiO ₂ , SnO ₂ , MnO ₂ , ZrO _2, etc. These components are exemplified. These components can be contained up to 15% or less. Preferably it is 10% or less.
The glass of the present invention does not contain PbO.

The raw materials were prepared and mixed so as to have the composition shown in mole percentages in the columns from B ₂ O ₃ to Al ₂ O _{3 in} Table 1. This was heated to 1400 ° C. using a platinum crucible and melted for 60 minutes. Examples 1-22 are examples, and examples 23-27 are comparative examples. Among these, since it was recognized that Examples 9 and 10 were translucent and phase-separated, the measurement described below was not performed. In addition, Table 2 shows the mass percentage display composition of each glass.

A part of the obtained molten glass was poured into a stainless steel roller to be flaked. The obtained glass flakes were dry pulverized with an alumina ball mill for 16 hours and then subjected to airflow classification to produce a glass powder having an average particle diameter (D ₅₀ ) of 2 to 4 μm. In the present specification, D ₅₀ refers to a value measured by a laser diffraction / scattering method.
Using this glass powder as a sample, a glass transition point (Tg) and Ts were measured using a differential thermal analyzer (DTA) (unit: ° C.).

The remaining molten glass was poured into a stainless steel mold and gradually cooled.
A part of the slowly cooled glass was processed into a cylindrical shape having a length of 20 mm and a diameter of 5 mm, and α of the glass was measured using a thermal expansion meter TMA-8310 manufactured by Rigaku Corporation using quartz glass as a standard sample (unit: 10 ⁻⁷ / ° C.).

  The other part of the slowly cooled glass is processed into a plate shape having a thickness of about 5 mm, and an ultrasonic thickness meter 35DL manufactured by Olympus NDT is used. The elastic modulus (Young's modulus) E (unit: GPa) was measured by the “sonic pulse method”.

In addition, one side of the glass processed into a plate shape is mirror-polished, and CIL is measured by the above-described method using a test piece which is kept at 500 to 520 ° C. for 1 hour to remove residual stress. (G / cm ² ).

H / H ₀ is a glass substrate having a size of 100 mm × 100 mm and a thickness of 1.8 mm, placed on a water-resistant abrasive paper having a particle size of # 1500, and from the height of 3 cm on the upper surface of the glass substrate. A 22 g stainless steel ball is dropped. When the glass substrate is not broken by the fall of the stainless steel ball, the drop height is increased by 5 mm and the stainless steel ball is dropped. The drop height is increased in steps of 5 mm until the glass substrate breaks, and the stainless steel ball is dropped.
Such glass substrate fracture test repeated five times, the average value of fracture height, thereby providing an H _0. H is an average value of fracture heights measured in the same manner as H ₀ for a glass substrate with a glass layer in which a glass layer is formed on one surface of the glass substrate so as to have a film thickness of 20 μm with partition wall forming glass. is there. All the examples shown in Table 1 are evaluations of glass layers formed so as to have a film thickness of 20 μm.
That is, the addition of placing on the waterproof abrasive paper in the same manner as H ₀ repeatedly measuring glass substrate destructive testing with the glass layer 5 times, resulting fracture height the surface being covered by glass for forming barrier ribs in the lower The average value was set to H.

In CIL, molten glass is poured into a stainless steel mold and gradually cooled.
The slowly cooled glass is processed into a sheet glass, and one surface thereof is mirror-polished to obtain a glass test piece having a typical size of 50 mm × 50 mm and a thickness of 10 mm.
Using this glass test piece, using a Vickers hardness tester, a Vickers indenter is pushed into the surface of the glass test piece for 15 seconds in a glove box having a relative humidity of 35% or less, and the number of cracks is measured. The indentation load at that time was measured between 10 g and 1 kg, and the load with two cracks was measured. When the number of cracks did not reach 2 even at 1 kg, it was described as> 1000.
In addition, circular electrodes with a diameter of 38 mm were provided on both surfaces of a plate-like sample having a thickness of about 3 mm, and the relative dielectric constant ε at 1 MHz was measured using an LCR meter 4192A manufactured by Yokogawa Hewlett-Packard Company.

  Table 1 shows the measurement results or calculation results obtained in this way. In the table, “-” indicates that measurement or calculation was not performed.

  It can be used for bonding, sealing, coating of electronic components, binders for pastes for electronic circuit components such as conductor pastes and resistance pastes, and dielectric layers and partition walls of plasma displays and fluorescent display tubes.

Claims (5)

Lead-free glass having a total content of B ₂ O ₃ , SiO _2, and Al ₂ O ₃ of 72% or more and a Young's modulus at room temperature of 85 GPa or less in terms of mol% based on oxide. The total content of B ₂ O ₃ , SiO _2, and Al ₂ O ₃ is 72% or more, Li ₂ O is 5 to 19%, and K ₂ O / (Li ₂ O + Na). ₂ O) lead-free glass for forming partition walls having a molar ratio of 1 or less.   The lead-free glass for barrier rib formation according to claim 1 or 2, wherein the Young's modulus at room temperature is 80 GPa or less. _{(B 2 O 3 + SiO 2} + Al 2 O 3) / (Li 2 O + Na 2 O + K 2 O) barrier-forming Pb-free glass according to any one claims 1 to 3 molar ratio is 4.2 or more represented by . As represented by mol% based on _oxides, B 2 _{O 3} of 20-55%, the SiO ₂ 10 to 50%, the _Al 2 _{O 3} 4 to _20%, one of Li 2 O, Na ₂ O and _{K 2} O The lead-free glass according to any one of claims 1 to 4, which contains at least one kind and contains 5 to 20% in total and 0 to 20% ZnO.