JP2001180972A - Lead free glass with low melting point - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the lead free glass with low melting point which enables to seal and coat plasma display panel and fluorescent display tube at 600 deg.C or less and contains small amount of Bi2O3. SOLUTION: The lead free glass with low fusing point is produced with following composition in mol%: P2O5; 55-62, ZnO; 20-39, Al2O3; 3-15, Li2O+Na2O +K2O; 2-20, MgO+CaO+SrO+BaO; 0-20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-free low-melting glass used for sealing, coating or forming partition walls in a flat display panel such as a plasma display panel (PDP) and a fluorescent display tube (VFD).

[0002]

2. Description of the Related Art In recent years, low-melting glass powder used for sealing, coating, or forming partition walls of PDPs, VFDs and the like has been required to contain no lead. Conventionally, Bi ₂ O ₃ -based glass has been used as such a lead-free low-melting glass.
There is a problem that it is necessary to increase the content of ₂ O ₃ and that a large amount of expensive Bi raw material must be used.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a lead-free low-melting glass which can have a softening point of 600 ° C. or less without containing Bi ₂ O ₃ .

[0004]

SUMMARY OF THE INVENTION The present invention, in mol% based on the following _{oxides, P 2 O 5: 55~62,} ZnO: 20
_{~39, Al 2 O 3: 3~15} , Li 2 O: 0~20, N
_{a 2 O: 0~20, K 2} O: 0~20, MgO: 0~2
0, CaO: 0 to 20, SrO: 0 to 20, BaO: 0
20, essentially made _{from, Li 2 O + Na 2 O} + K 2 O
Provides a lead-free low-melting glass in which MgO + CaO + SrO + BaO is 0 to 20 mol%.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION When the lead-free low-melting glass of the present invention (hereinafter simply referred to as the glass of the present invention) is used for sealing, coating, or forming partition walls, it is used in the form of powder. This powdered glass is usually mixed with a low-expansion ceramic filler, a heat-resistant pigment, or the like, if necessary, and then kneaded with a vehicle to form a paste. This glass paste is applied to a predetermined portion of the underlying glass and fired. The base glass referred to here includes those in which a transparent conductive film or the like is coated on the glass.

The softening point (T _s ) of the glass of the present invention is 580
It is preferable that the temperature is not higher than ° C. If the temperature exceeds 580 ° C, PD
It may be difficult to use P, VFD, or the like for sealing, coating, or forming a partition. More preferably 560
° C or lower, particularly preferably 550 ° C or lower. Also, T
_s is preferably 500 ° C. or higher. If the temperature is lower than 500 ° C., it may be difficult to use it for coating or forming a partition in PDP, VFD, and the like. It is more preferably at least 510 ° C, particularly preferably at least 520 ° C, most preferably at least 530 ° C.

The crystallization temperature (T) of the glass of the present invention_c) Is T_s
It is preferable that the temperature is higher by 40 ° C. or more than that. T_cAnd T_sDifference
(T_c-T_s) Is less than 40 ° C, it tends to crystallize during firing.
Could be. Where T_cIndicates differential thermal analysis (DT
A) is the crystallization peak temperature obtained by A)
If no peak is observed, T_c= ∞. (T_c−
T _s) Is more preferably 50 ° C. or higher. further
Preferably at least 60 ° C, particularly preferably at least 70 ° C, most preferably
Is also preferably 80 ° C. or higher.

The linear expansion coefficient of the glass of the present invention at 50 to 250 ° C. is preferably 120 × 10 ⁻⁷ / ° C. or less. If it exceeds 120 × 10 ⁻⁷ / ° C., the coefficient of linear expansion of a fired product of glass frit described below may be too large. It is more preferably at most 110 × 10 ⁻⁷ / ° C., particularly preferably at most 100 × 10 ⁻⁷ / ° C. Further, the coefficient of linear expansion is preferably 60 × 10 ⁻⁷ / ° C. or more. Hereinafter, the coefficient of linear expansion at 50 to 250 ° C. is simply referred to as an expansion coefficient.

Next, the composition of the glass of the present invention will be described below by simply writing mol% as%. P ₂ O ₅ is a network former and is essential. If it is less than 55%, the softening point becomes too high. If it exceeds 62%, the chemical durability, particularly the water resistance, is reduced. It is preferably at most 60%, more preferably at most 59%, particularly preferably at most 58%.

ZnO has an effect of stabilizing glass, an effect of improving chemical durability, particularly water resistance, an effect of lowering an expansion coefficient, or an effect of lowering a softening point,
Required. If it is less than 20%, the effect is too small. It is preferably at least 21%. If it exceeds 39%, it tends to crystallize during firing, or the softening point is too high. It is preferably at most 35%, more preferably at most 32%.

Al ₂ O ₃ has an effect of increasing chemical durability, particularly water resistance, and is essential. If it is less than 3%, the effect is small. It is preferably at least 4%. If it exceeds 15%, the softening point becomes too high. Preferably it is 10% or less.

Li ₂ O, Na ₂ O and K ₂ O all have the effect of lowering the softening point and increasing the fluidity, and must contain at least one of these three components. Li
The content of each of ₂ O, Na ₂ O and K ₂ O is 20%
Must be: If it exceeds 20%, the chemical durability decreases. Preferably it is 10% or less.

The total content of Li ₂ O, Na ₂ O and K ₂ O is 2 to 20%. If it is less than 2%, the softening point becomes too high. It is preferably at least 4%. If it exceeds 20%, the chemical durability is reduced or the expansion coefficient is too large. Preferably it is 15% or less, more preferably 10% or less.

Each of MgO, CaO, SrO and BaO is not essential, but each may contain up to 20% in order to stabilize the glass. If it exceeds 20%, devitrification may easily occur. More preferably 15% or less,
It is particularly preferably at most 12%.

When one or more of MgO, CaO, SrO and BaO are contained, the total content thereof is 20%.
% Is preferable. If it exceeds 20%, devitrification may easily occur. It is more preferably at most 15%, particularly preferably at most 12%.

The glass of the present invention consists essentially of the above components, but may contain other components in a total amount of up to 10 mol%, more preferably up to 5 mol%. Such components include rare earth oxides such as La ₂ O ₃ and CeO ₂ , B ₂ O ₃ , SiO ₂ , TiO ₂ , MnO, F
e ₂ O ₃ , CoO, NiO, CuO, Y ₂ O ₃ , ZrO ₂ ,
MoO ₃ , Rh ₂ O ₃ , PdO, Ag ₂ O, In ₂ O ₃ , Te
O ₂ , WO ₃ and Bi ₂ O ₃ are exemplified.

Bi ₂ O ₃ has the effect of lowering the softening point, but is also a coloring component, and is preferably at most 4 mol%, more preferably at most 2 mol% in applications where coloring is a problem. In such an application, it is most preferable that it is not substantially contained, that is, it is not more than the impurity level.

Further, the glass of the present invention contains substantially no PbO, CdO or V ₂ O ₅ . Further, the glass of the present invention preferably does not substantially contain a halogen element such as F or Cl. The halogen element gasifies during firing, and may react with the phosphor in PDP, VFD, etc. to degrade the phosphor, or may adhere to the VFD filament to lower the emission.

When the glass powder of the present invention is used for sealing, coating, or forming partition walls of PDP, VFD, etc., it may be mixed with a low expansion ceramic filler or a heat-resistant pigment to be used as a glass ceramic composition. Hereinafter, a powder containing at least one of the low expansion ceramic filler and the heat-resistant pigment and the glass powder of the present invention is referred to as a glass ceramic composition. The low expansion ceramic filler is a ceramic filler having an expansion coefficient of 70 × 10 ⁻⁷ / ° C. or less, and is a component that reduces the expansion coefficient of a fired product obtained by firing a glass ceramic composition. One or more powders selected from alumina, mullite, zircon, cordierite, aluminum titanate, β-spodumene, α-quartz, β-quartz solid solution and β-eucryptite may be easily handled or obtained. It is preferable from the viewpoint of easiness.

Examples of heat-resistant pigments include white pigments such as titania, Fe-Mn double oxides, Fe-Co-
Black pigments such as Cr double oxides and Fe-Mn-Al double oxides are exemplified.

The total content of the low expansion ceramic filler and the heat-resistant pigment in the glass ceramic composition is 100 parts by mass with respect to 100 parts by mass of the glass powder of the present invention.
It is preferable that the amount is not more than part by mass. If it exceeds 100 parts by mass, the fluidity may decrease. It is more preferably at most 90 parts by mass, particularly preferably at most 80 parts by mass.

The expansion coefficient of the fired product obtained by firing the glass ceramic composition is 60 × 10 ^{-7 to} 90 × 10
It is preferably in the range of ^-7 / ° C. If the expansion coefficient is out of this range, expansion matching between the fired material and the underlying glass may be difficult.

The glass ceramic composition is usually mixed with a vehicle to form a glass paste. Mixing with the vehicle is performed using a mortar, a three-roll mill, or the like.
The glass paste is applied to a predetermined portion of an underlying glass, for example, a glass substrate or a thin film formed on the glass substrate, by a method such as screen printing.
Baking is performed below, and sealing, coating, partition wall formation, and the like are performed. As the vehicle, those obtained by dissolving a resin such as ethyl cellulose or nitrocellulose in a solvent such as α-terpineol, butyl carbitol acetate, or isopentyl acetate are generally used.

[0024]

EXAMPLES Raw materials were prepared and mixed so as to have the composition shown in mol% in the column of P ₂ O _{5 to} CaO in the table. Note that P ₂
As a raw material for O _5, an aqueous solution of orthophosphoric acid or zinc pyrophosphate was used. The mixed raw material was put in a platinum crucible and melted at 1250 ° C. for 30 minutes. Next, the molten glass was poured into a stainless steel roller and flaked. The obtained flaky glass was pulverized with an alumina ball mill for 105 minutes to obtain glass powder.

With respect to the obtained glass powder, glass transition point T _g (unit: ° C.), softening point T _s (unit: ° C.), crystallization peak temperature T _c (unit: ° C.), expansion coefficient α (unit: 10) ^-7
/ ° C), elution amount Q _d (%), flow button diameter D (unit:
mm) and flow button appearance were measured and evaluated. The method is described below, and the results are shown in the table.

Glass transition point, softening point, crystallization peak temperature: A glass powder having an average particle size of 10 to 20 μm is used as a sample and subjected to differential thermal analysis at a temperature rising rate of 10 ° C./min.
It was measured in the range up to 0 ° C. Alumina powder was used as a standard substance. When firing at 560 ° C., the softening point is 56
It is preferable that the crystallization peak temperature is 0 ° C or lower and the crystallization peak temperature is 620 ° C or higher. When firing at 580 ° C., the softening point is 5
It is preferable that the crystallization peak temperature is not higher than 650 ° C and not higher than 80 ° C. For Examples 1, 2, and 4, no crystallization peak was observed, and the results are indicated by Δ in the table.

Expansion coefficient: The molten glass was poured onto a stainless steel plate and gradually cooled near the glass transition point. A sample obtained by processing the slowly cooled glass into a rod having a diameter of 2 mm and a length of 20 mm was used as a sample, and the average linear expansion coefficient in the range of 50 to 250 ° C. was measured with a differential thermal dilatometer using quartz glass as a standard sample. The expansion coefficient of Example 5 was not measured.

Elution amount: The same sample as the sample for measuring the expansion coefficient was immersed in water at 80 ° C. for 24 hours, and the weight loss rate was calculated from the weight of the sample before and after immersion, and expressed as%. This elution amount is an index of water resistance and is preferably 1% or less. Example 2,
The elution amounts of 5 and 6 were not measured.

Flow button diameter: 3 g of glass powder and diameter of 1
A sample formed by pressure-forming into a 2.7 mm cylindrical shape was used as a sample.
This sample was placed at 560 ° C. for 10 minutes for Examples 1-4,
Examples 5 and 6 were kept at 580 ° C. for 10 minutes, respectively. The diameter of the sample after the heat treatment was measured. This diameter is preferably at least 13 mm, more preferably at least 14 mm.

[0030]

[Table 1]

[0031]

By using the glass of the present invention, P
Sealing, coating, partition wall formation, and the like in DP, VFD, and the like can be performed at a firing temperature of 600 ° C. or lower. Further, in the glass of the present invention, the content of Bi ₂ O ₃ can be suppressed, and the amount of expensive Bi raw material used can be reduced.

Continued on front page F term (reference) 4G062 AA09 BB09 CC10 DA01 DB03 DB04 DC01 DD06 DE04 DE05 DF01 EA01 EA02 EA03 EA04 EB01 EB02 EB03 EB04 EC01 EC02 EC03 EC04 ED01 ED02 ED03 ED04 EE01 EE02 EF03 EF03 EF03 FA10 FB01 FC01 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 MM03 KK03 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK03 KK05 KK05 KK05 KK05 AA11 AA14 BA35

Claims (1)

[Claims] In 1. A following oxides in _{mol%, P 2 O 5 55~62, ZnO} 20~39, Al 2 O 3 3~15, Li 2 O 0~20, Na 2 O 0~20, _{K 2 O 0~20, MgO 0~20,} CaO 0~20, SrO 0~20, BaO 0~20, essentially made _{from, Li 2 O + Na 2 O} + K 2 O is 2-2
0 mol%, MgO + CaO + SrO + BaO is 0 to 20
Lead-free low melting glass which is mol%.