JP6911390B2 - Bismuth-based lead-free glass composition - Google Patents

Description

The present invention relates to a bismuth-based lead-free glass composition, and more specifically, to a bismuth-based lead-free glass composition capable of effectively preventing the generation of lumps and repellents and forming a glass layer having excellent surface smoothness. ..

Substrates for flexible devices used for organic EL lighting, organic EL displays, organic solar cells, etc. are required to have smoothness and insulation properties in addition to barrier properties such as moisture barrier property and vapor barrier property.
Patent Document 1 below proposes a structure of an organic EL element in which a transparent conductive layer, an organic light emitting medium layer, and a cathode layer are sequentially laminated on a plastic film base material, and a metal foil is laminated via an adhesive layer. However, such a plastic film base material is not satisfactory in terms of moisture barrier property.
Further, Patent Document 2 below proposes a substrate for a flexible device in which a flattening layer made of a polyimide resin is provided on a stainless steel base material, but since the polyimide resin has high water absorption, it also has a moisture barrier property. I am not satisfied with it.
Further, Patent Document 3 below proposes a flexible solar cell substrate in which silica-based glass is formed on a stainless steel base material. Silica-based glass generally has a smaller coefficient of thermal expansion than stainless steel, and is compatible with stainless steel base materials. In addition to lacking adhesion, silica-based glass has the problem of being vulnerable to bending and impact.

In order to solve such a problem, the present inventors have formed a Ni plating layer on the surface of a metal base material, and laminated bismuth-based glass having electrical insulation on the surface of the Ni plating layer. A metal substrate for a flexible device has been proposed (Patent Document 4).

Japanese Unexamined Patent Publication No. 2004-171806 Japanese Unexamined Patent Publication No. 2011-97007 Japanese Unexamined Patent Publication No. 2006-80370 Japanese Unexamined Patent Publication No. 2014-107053

The metal substrate for a flexible device is laminated with bismuth-based glass having excellent moisture barrier properties and excellent adhesion to a metal substrate, and has excellent insulation and flatness, and is lightweight and flexible. However, on the surface of the glass layer after firing, bumps that are minute protrusions and repelling that are minute recesses may occur, and such minute defects may impair the smoothness of the glass layer.
As a result of researching the causes of these minute defects formed on the surface of the glass layer, the present inventors have found that these minute defects formed on the surface of the glass layer cause crystals to be generated from the glass and bubbles to burst. It was found that it was formed due to scars, decomposition products of resin, etc., and in particular, repelling was caused by the influence of surface tension based on the disorder of the glass layer due to the rupture scars of bubbles and the crystallization of glass.

Therefore, an object of the present invention is a bismuth-based lead-free glass layer that is excellent in moisture barrier property and adhesion to a metal substrate, and can form a glass layer having excellent surface smoothness in which the generation of lumps and repellent is effectively suppressed. To provide a glass composition.

According to the present invention, it is a glass composition used for a metal substrate for a flexible device, in which Bi ₂ O ₃ is 70 to 84% by weight, Zn O is 10 to 12% by weight, and B ₂ O ₃ is 6 to 12% by weight. A bismuth-based lead-free glass composition is provided, which is characterized by being contained in an amount of.
In the bismuth-based lead-free glass composition of the present invention,
1. 1. Contains SiO ₂ and / or Al ₂ O ₃ , the content of SiO ₂ is 0 to 2% by weight, and _{the content of Al 2} O ₃ is 0 to 1% by weight (however, SiO ₂ and Al ₂ O). ₍ Does not include the case where both of 3 are zero),
2. It contains CuO and / or NiO, and the content of CuO is 0 to 2% by weight and the content of NiO is 0 to 2% by weight (excluding the case where both CuO and NiO are zero). ,
3. 3. Containing any of Y ₂ O ₃ , ZrO ₂ , La ₂ O ₃ , CeO ₂ , TiO ₂ , CoO, and Fe ₂ O ₃ in an amount of 1.5% by weight or less (not including zero).
Is preferable.

According to the present invention, a bismuth-based lead-free glass composition paste composed of the powder and vehicle of the glass composition, wherein the average particle size of the glass composition powder is 20 μm or less. A lead-free glass composition paste is provided.

The bismuth-based lead-free glass composition of the present invention does not contain lead, is excellent in environmental friendliness, and has a glass composition that is difficult to crystallize. A glass layer having excellent properties can be formed.
Moreover, since it has excellent adhesion to a metal base material and does not generate bumps or repellent even in a thin layer, it can be suitably used for a substrate for organic EL such as a substrate for a flexible device.
Further, since the bismuth-based lead-free glass composition of the present invention has a dense structure and can completely prevent the permeation of water, it exhibits excellent water barrier properties as an insulating layer for electronic devices using a metal substrate. It is possible to do.

(Bismuth-based lead-free glass composition)
The important feature of the bismuth-based lead-free glass composition of the present invention is that it contains Bi ₂ O ₃ in an amount of 70 to 84% by weight, Zn O in _{an amount of 10 to 12% by weight, and B 2 O 3} in an amount of 6 to 12% by weight. Therefore, when these components are contained in the above range and are in the range around the eutectic point, glass that is difficult to crystallize is formed.

In the present invention, Bi ₂ O ₃ is a main component for lowering the viscosity of glass, and is preferably contained in an amount of 70 to 84% by weight, particularly 75 to 82% by weight. _{If the content of Bi 2} O ₃ is lower than the above range, the softening point becomes high and the viscosity becomes too high, while if _{the content of Bi 2} O ₃ is higher than the above range, crystallization is promoted. There is a risk of bumps and repelling.
Further, ZnO is a component for stabilizing the glass and suppressing devitrification when the glass is melted, and is preferably contained in an amount of 10 to 12% by weight, particularly 10.5 to 11% by weight. .. If the ZnO content is less than the above range, the durability of the glass is lowered and the glass is easily devitrified. In addition, the glass transition temperature becomes high, and the smoothness of the fired glass decreases. On the other hand, if the content of ZnO is larger than the above range, crystallization is promoted, there is a risk of lumps and repellency, and durability is lowered.
Further, B ₂ O ₃ is a component forming a glass network, and is preferably contained in an amount of 6 to 12% by weight, particularly 6 to 7% by weight. _{If the content of B 2} O ₃ is less than the above range, the glass becomes unstable and its durability is lowered, and it is easy to crystallize at the time of firing, which may cause lumps and cissing. On the other hand, if _{the content of B 2} O ₃ is larger than the above range, the water resistance is lowered.

In the glass composition of the present invention, it is preferable to contain _{SiO 2} and / or Al ₂ O _{3 in addition to the above essential components.}
SiO ₂ forms a glass network together with B ₂ O ₃ and makes it possible to further stabilize the glass. The blending amount of SiO ₂ is preferably 2% by weight or less, particularly preferably in the range of 1.2 to 1.5% by weight. _{If the blending amount of SiO 2} is larger than the above range, the meltability of the glass may decrease as compared with the case where the SiO 2 is blended in the above range.
Further, by blending Al ₂ O ₃ , it becomes possible to further stabilize the glass. The blending amount of Al ₂ O ₃ is preferably 1% by weight or less, particularly preferably in the range of 0.4 to 0.6% by weight. If _{the blending amount of Al 2} O ₃ is larger than the above range, the meltability of the glass may decrease as compared with the case of blending in the above range.

In the glass composition of the present invention, it is preferable to further contain CuO and / or NiO in addition to the above essential components.
By blending CuO in an amount of 2% by weight or less, particularly 1.3 to 1.6% by weight, the meltability of the glass is improved. If the amount of CuO blended is larger than the above range, the adhesion to the metal substrate may decrease.
Further, by blending NiO in an amount of 2% by weight or less, particularly 1.3 to 1.6% by weight, the meltability of the glass is improved as in the case where CuO is blended. If the amount of NiO blended is larger than the above range, the adhesion to the metal substrate may decrease.

In the glass composition of the present invention, in addition to the above essential components, any one of Y ₂ O ₃ , ZrO ₂ , La ₂ O ₃ , CeO ₂ , TiO ₂ , CoO, and Fe ₂ O ₃ is further added by 1.5 weight. It is preferable to contain it in an amount of% or less.
By containing any of Y ₂ O ₃ , ZrO ₂ , La ₂ O ₃ , CeO ₂ , TiO ₂ , CoO, and Fe ₂ O _{3 in} the above amounts, the durability of the glass can be improved. If the amount of these components blended is larger than the range, the durability of the glass may be lowered. It is possible to use a plurality of types of these components in combination, but in that case, the total amount is preferably 1.5% by weight or less.

(Bismuth-based lead-free glass composition paste)
The bismuth-based lead-free glass composition paste of the present invention is composed of the above-mentioned powder and vehicle of the glass composition, and an important feature is that the average particle size of the glass composition powder is 20 μm or less.
The vehicle that constitutes the paste together with the glass composition powder is used to adjust the viscosity of the paste, and is prepared by dissolving an organic binder in a solvent.
The glass composition paste preferably contains the above-mentioned glass composition powder in an amount of 30 to 80% by weight, an organic binder in an amount of 0 to 10% by weight (not containing zero), and a solvent in an amount of 10 to 70% by weight. Is. When the amount of the glass composition powder is smaller than the above range, the paste viscosity becomes low and it becomes difficult to form a glass layer having a desired thickness, while the amount of the glass composition powder is larger than the above range. The paste viscosity becomes too high and the coatability becomes inferior. Further, when the amount of the organic binder is smaller than the above range, the coatability becomes inferior, while when the amount of the organic binder is larger than the above range, the unfired organic substance may remain after firing. be. Further, when the amount of the solvent is smaller than the above range, the paste viscosity becomes too high and the coatability becomes inferior, while when the amount of the solvent is larger than the above range, the paste viscosity becomes too low. It becomes difficult to form a glass layer having a desired thickness.

The organic binder is not limited to this, but is a cellulose-based resin such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, oxyethyl cellulose, benzyl cellulose, propyl cellulose, nitro cellulose; methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, etc. Organic resins such as acrylic resins obtained by polymerizing one or more of acrylic monomers such as butyl acrylate and 2-hydroxyethyl acrylate; aliphatic polyolefin carbonate resins such as polypropylene carbonate can be exemplified.
The solvent is appropriately selected depending on the organic binder used, and is not limited to this, but in the case of a cellulose-based resin, water, turpineol, butyl carbitol acetate, ethyl carbitol acetate, etc .; in the case of an acrylic resin, methyl ethyl ketone, turpineol, etc. Solvents such as butyl carbitol acetate and ethyl carbitol acetate; in the case of aliphatic polyolefin carbonates, propylene carbonate, triacetin and the like; can be used.

The glass composition paste is obtained by mixing and dispersing the glass composition powder obtained by crushing the glass frit made of the above-mentioned bismuth-based lead-free glass composition and the vehicle.
The glass composition powder is obtained by mixing the above-mentioned glass composition, heating at a temperature of 800 to 1200 ° C. to melt vitrify, quenching to obtain a glass frit, and then pulverizing the glass composition powder. Examples of the crushing method include conventionally known methods such as JET crushing, rapid mill crushing, and ball mill crushing.
In the present invention, it is important that the average particle size of the glass composition powder is in the range of 20 μm or less, preferably 1 to 10 μm, more preferably 1 to 5 μm in order to obtain a smooth glass surface. In order to obtain such a fine powder, it is preferable to use JET crushing among the above crushing methods.
In the present invention, the average particle size of the glass composition powder is a value measured by a laser diffraction / scattering method.

Next, the obtained glass composition powder having an average particle size of 20 μm or less and the vehicle are mixed and dispersed.
As a mixing / dispersing method, a rotary mixer equipped with a stirring blade, a bead mill, a paint shaker, a roll mill, an agate mortar, an ultrasonic wave, or the like can be exemplified, but a bead mill, a paint shaker, or a roll mill is preferable. , It is desirable to mix and disperse.
Further, if necessary, a known thickener, dispersant or the like can be added to the glass composition paste according to a known formulation.

(Formation of glass layer)
The glass composition paste of the present invention is applied to substrates such as glass substrates, ceramics substrates, aluminum substrates, stainless steel substrates, steel plates, various plated steel plates including Ni, and titanium substrates, for example, bar coaters, die coaters, roll coaters, and gravure. It can be coated by a coater, screen printing, offset printing, an applicator, or the like.
The coated glass paste is dried at a temperature of 80-180 ° C. After drying, if necessary, remove the binder. The binder removal treatment is preferably performed by heating at a temperature of 180 to 450 ° C. for 10 minutes or more.
After drying, the coated surface, which has been subjected to the binder removal treatment if necessary, is fired at a temperature of 550 to 900 ° C., preferably 650 to 850 ° C. for 10 to 300 seconds to form a glass layer. If the firing temperature is lower than the above range, melting may be insufficient compared to the case where it is in the above range, while if the firing temperature is higher than the above range, it is in the above range. In comparison, it may affect the substrate.

The glass composition of the present invention preferably has a softening point temperature in the range of 300 to 500 ° C. Bismuth-based glass, which softens at a temperature lower than the above range, is more likely to crystallize during firing than in the above range, and when it is necessary to perform a binder removal treatment, it softens at the temperature of the binder removal treatment. The decomposition gas of the binder may enter the glass and cause pinholes. On the other hand, when the softening point temperature is higher than the above range, a higher temperature is required at the time of firing as compared with the case where it is in the above range, and the substrate itself may be deformed or deteriorated, which may make film formation difficult. Further, when firing at a relatively low temperature, the glass may be insufficiently melted and the surface smoothness may be lost.

(Examples 1 to 9, Comparative Examples 1 to 3)
Glass composition: A bismuth-based glass composition having the composition shown in Table 1 was used.
Vehicle: A vehicle composed of methyl cellulose as an organic binder and water as a solvent, which are blended in a weight ratio of 1:99, was used.
The glass composition powder shown in Table 1 and the vehicle were mixed in a mortar so that the weight ratio was 50:50, and dispersion treatment was performed with a ceramic roll to prepare a glass paste for forming a glass layer.
A Ni-plated steel plate is used as the substrate, the surface is wiped off with gauze soaked in alcohol, degreased, and then a glass paste is applied on the heat-treated Ni-plated layer with a bar coater so that the film thickness after firing is 20 μm. And formed a coating film. Next, using an electric furnace, drying (temperature: 120 ° C., time: 20 minutes) and firing (temperature: 750 ° C., time: 15 seconds) were performed to prepare a substrate for a flexible device.

(Evaluation results)
The formed glass layer was evaluated as follows regarding the presence or absence of repellency and the presence or absence of crystallization (bumps) in the glass film. The results are shown in Table 1.
The evaluation criteria are as follows.
[Criteria for repelling]
For a substrate for a flexible device having a size of 100 × 100 mm, the presence or absence of repellency that could be visually confirmed was evaluated according to the following evaluation criteria.
◎: No repellent ○: Number of repellents less than 5 △: Number of repellents 5 or more and less than 10 ×: Number of repellents 10 or more [Crystallization]
For a substrate for a flexible device having a size of 100 × 100 mm, it was judged by the presence or absence of crystallization that could be visually confirmed.

Since the bismuth-based lead-free glass composition of the present invention can form a glass layer having excellent surface smoothness that does not generate lumps or repellents, it can be effectively used as a substrate for electronic devices, particularly a flexible device substrate related to organic EL.

Claims (5)

A glass composition used for a metal substrate for a flexible device, which contains Bi ₂ O ₃ in an amount of 70 to 84% by weight, Zn O in _{an amount of 10 to 12% by weight, and B 2 O 3} in an amount of 6 to 12% by weight. A bismuth-based lead-free glass composition characterized by. Contains SiO ₂ and / or Al ₂ O ₃ , the content of SiO ₂ is 0 to 2% by weight, and _{the content of Al 2} O ₃ is 0 to 1% by weight ( _{both SiO 2} and Al ₂ O ₃ ). The bismuth-based lead-free glass composition according to claim 1, wherein the value is zero. Claim that contains CuO and / or NiO, the content of CuO is 0 to 2% by weight, and the content of NiO is 0 to 2% by weight (excluding the case where both CuO and NiO are zero). The bismuth-based lead-free glass composition according to 1 or 2. Claims 1 to 1 containing any of Y ₂ O ₃ , ZrO ₂ , La ₂ O ₃ , CeO ₂ , TiO ₂ , CoO, and Fe ₂ O ₃ in an amount of 1.5% by weight or less (not including zero). The bismuth-based lead-free glass composition according to any one of 3. A bismuth-based lead-free glass composition paste composed of the powder and vehicle of the glass composition according to any one of claims 1 to 4, wherein the average particle size of the glass composition powder is 20 μm or less. Bismus-based lead-free glass composition paste.