JP2013166656A - Sealing material paste, method for coating the same, and glass substrate with sealing material layer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance long time reliability of an organic EL device or others having an organic EL element package by devising a sealing material paste capable of forming a sealing material layer excellent thick after firing and excellent in surface smoothness, a method for coating the same, and a glass substrate with a sealing material layer using the same.SOLUTION: A sealing material paste includes inorganic powder and vehicle, the inorganic powder includes SnO-containing glass powder and pigment, the vehicle includes resin binder and solvent, contents of the inorganic powder, the resin binder, and the solvent are 42 to 52, 8 to 18, and 35 to 45 in terms of mass ratio, respectively.

Description

  The present invention relates to a sealing material paste and a glass substrate with a sealing material layer using the same, and specifically, a sealing material paste suitable for laser sealing (hereinafter referred to as laser sealing) and the same. The present invention relates to a glass substrate with a sealing material layer.

  In recent years, organic EL displays have attracted attention as flat display panels. Since the organic EL display can be driven by a direct current voltage, the driving circuit can be simplified, and there are advantages such as a liquid crystal display that does not depend on the viewing angle, is bright because of self-emission, and has a high response speed. Currently, organic EL displays are mainly used in small portable devices such as mobile phones, but in the future, application to ultra-thin televisions is expected. Note that the organic EL display is mainly driven by disposing an active element such as a thin film transistor (TFT) in each pixel in the same manner as a liquid crystal display.

  The organic EL display is composed of two glass substrates, a negative electrode such as metal, an organic light emitting layer, a positive electrode such as ITO, and an adhesive material. Conventionally, an organic resin adhesive material such as an epoxy resin having a low temperature curability or an ultraviolet curable resin has been used as the adhesive material. However, organic resin adhesive materials cannot completely block gas intrusion. For this reason, when an organic resin adhesive material is used, the airtightness inside the organic EL display cannot be maintained, and as a result, the organic light emitting layer having low water resistance is easily deteriorated, and the organic EL display There is a problem that the display characteristics of the display deteriorate with time. In addition, the organic resin-based adhesive material has an advantage that the glass substrates can be bonded to each other at a low temperature. However, since the water resistance is low, when the organic EL display is used for a long time, the reliability of the display is likely to be lowered. .

  On the other hand, the sealing material containing glass powder is excellent in water resistance as compared with the organic resin-based adhesive material, and is suitable for ensuring airtightness inside the organic EL display.

  However, since glass powder generally has a softening temperature of 300 ° C. or higher, it has been difficult to apply it to an organic EL display. More specifically, when sealing glass substrates with a sealing material containing glass powder, the entire organic EL display is put into an electric furnace and baked at a temperature equal to or higher than the softening temperature of the glass powder. It was necessary to soften and flow. However, since the active element used in the organic EL display has only heat resistance of about 120 to 130 ° C., sealing the glass substrates by this method damages the active element due to heat, and the organic EL display. Display characteristics will deteriorate. In addition, since the organic light emitting material also has poor heat resistance, sealing the glass substrates by this method damages the organic light emitting material due to heat and degrades the display characteristics of the organic EL display.

  In view of such circumstances, in recent years, laser sealing has been studied as a method for sealing an organic EL display (for example, Patent Documents 1 and 2). According to the laser sealing, only the portion to be sealed can be locally heated by the laser beam, so that the glass substrates can be sealed together while preventing thermal degradation of the active element or the like.

US Pat. No. 6,416,375 JP 2006-315902 A

  When performing laser sealing as described above, it is preferable that the sealing material paste is dried and fired after being applied to the substrate. Thus, the sealing material paste is dried and baked to form the sealing material layer in advance, whereby the sealing material layer and the object to be sealed can be brought into close contact with each other, and laser sealing is performed with a low-power laser. be able to. At this time, if the sealing material layer is thick, it is necessary to increase the output of the laser, and the amount of heat generated in the sealing portion tends to increase. In addition, the sealing material layer is easily maintained in a high temperature state, which may lead to thermal deterioration of an active element or the like disposed around the sealing material layer. Therefore, the thickness of the sealing material layer after firing is preferably as thin as possible.

  As a method of thinning the sealing material layer after firing, it is conceivable to apply a thin sealing material paste in advance. However, for example, when the sealing material paste is applied by a screen printing method, it is necessary to prepare a very thin special screen mask in order to apply the sealing material paste thinly. Such a special screen mask is expensive, and the manufacturing cost becomes high.

  As another method of thinning the sealing material layer after firing, a method of increasing the content of the volatile solvent in the sealing material paste can be considered. If the content ratio of the volatile solvent is increased in advance, the solvent volatilizes during drying and baking, and the sealing material layer after baking can be thinned. However, simply increasing the content of the solvent may impair the surface smoothness of the sealing material layer after firing and may not provide sufficient sealing properties.

  The present invention has been made in view of the above problems, and a sealing material paste capable of forming a sealing material layer that is thin and excellent in surface smoothness after firing, a coating method thereof, and a sealing material layer using the same The technical problem is to improve the long-term reliability of an organic EL device or the like provided with an organic EL element package by creating an attached glass substrate.

  As a result of intensive studies, the present inventors adopted a vehicle containing an inorganic powder, a resin binder, and a solvent as a sealing material, and strictly controlled the content ratio of the inorganic powder, the resin binder, and the solvent. The present inventors have found that the above technical problem can be solved and propose as the present invention.

  That is, the sealing material paste of the present invention includes an inorganic powder and a vehicle, the inorganic powder includes at least a glass powder and a pigment, the vehicle includes a resin binder and a solvent, and the inorganic powder, the resin binder, and the solvent content. Is 42-52, 8-18, 35-45 by mass ratio. If the content of the inorganic powder, the resin binder, and the solvent is adjusted to 42 to 52, 8 to 18, 35 to 45 by mass ratio, the sealing material after firing is improved while improving the surface smoothness of the sealing material layer The layer can be made thin. As a result, it is possible to appropriately ensure the airtightness inside the organic EL device while preventing thermal deterioration of the organic EL element.

  Secondly, in the sealing material paste of the present invention, it is preferable that the inorganic powder further includes a refractory filler, and the maximum particle diameter D99 of the refractory filler is 3 μm or less. Since the refractory filler has a low thermal expansion coefficient, it is possible to reduce the thermal expansion coefficient of the sealing material layer. When the thermal expansion coefficient of the sealing material layer is lowered, the mechanical strength of the sealing material layer after laser sealing can be increased. Here, the “maximum particle size D99” refers to a value measured with a laser diffraction particle size distribution meter, and in an accumulated particle size distribution curve based on volume when measured with a laser diffraction particle size distribution meter, the integrated amount is the particle size distribution curve. The particle size is 99% cumulative from the smallest.

  Thirdly, the sealing material paste of the present invention is characterized in that the value of inorganic powder / vehicle is 0.7 to 1.1 by mass ratio. According to such a structure, the smoothness of the surface of the sealing material layer after baking can be improved. When the smoothness of the surface of the sealing material layer after firing is improved, laser sealing can be easily performed even with a low-power laser.

  Fourthly, in the sealing material paste of the present invention, the vehicle preferably contains a plurality of resin binders having different molecular weights. According to such a configuration, the sealing material paste can be easily adjusted to a viscosity suitable for printing.

  Fifth, in the sealing material paste of the present invention, it is preferable that the resin binder is an aliphatic polyolefin carbonate and the number average molecular weight thereof is 50,000 to 500,000. Aliphatic polyolefin carbonates can be fired in an inert atmosphere and can be easily debindered. Moreover, the viscosity suitable for screen printing can be easily adjusted by making the number average molecular weight of a resin binder into 50000-500000.

Sixth, in the sealing material paste of the present invention, the SnO-containing glass powder contains, as a glass composition, mol%, SnO 35 to 70%, P ₂ O ₅ 10 to 30%, and its maximum particle size. It is preferable that D99 is 10 μm or less. By regulating the maximum particle size D99 as described above, the sealing material paste can be printed with a uniform thickness.

  Seventhly, in the sealing material paste of the present invention, the pigment is preferably amorphous carbon or graphite, and the average particle diameter D50 of the primary particles is preferably 1 nm to 100 nm. Here, the “average particle size D50” refers to a value measured with a laser diffraction particle size distribution meter, and in an accumulated particle size distribution curve on a volume basis when measured with a laser diffraction particle size distribution meter, the integrated amount is the particle size. The particle size is 50% cumulative from the smallest.

  Eighth, the sealing material paste application method of the present invention is a method of applying the sealing material paste to an object to be sealed by a screen printing method, and the screen mask used for screen printing has a mesh number of 325 to 325. 500, the emulsion thickness of the screen mask used for screen printing is 1 to 20 μm, and the attack angle of the squeegee used for screen printing is 50 to 70 °. According to such a configuration, the sealing material paste according to the present invention can be uniformly applied to the glass substrate.

  Ninth, the glass substrate with a sealing material layer of the present invention is a glass substrate with a sealing material layer formed by applying a sealing material paste to a glass substrate, and is wet immediately after the sealing material paste is applied to the glass substrate. The average thickness of the sealing material layer in the state is 20 μm or less. According to such a glass substrate with a sealing material layer, the average thickness of the sealing material layer after drying can be made 10 μm or less, and the average thickness of the sealing material layer after firing can be made 5 μm or less. Here, “average thickness of the sealing material layer” refers to a value measured by a non-contact type laser film thickness meter.

  Tenth, the glass substrate with a sealing material layer of the present invention is a glass substrate with a sealing material layer formed by applying a sealing material paste to a glass substrate, and after applying the sealing material paste to the glass substrate, The average thickness of the sealing material layer in a dry state after drying is 10 μm or less. According to such a glass substrate with a sealing material layer, the average thickness of the sealing material layer after firing can be 5 μm or less.

  Hereinafter, the sealing material paste which concerns on embodiment of this invention is demonstrated. The sealing material paste according to the embodiment of the present invention includes an inorganic powder and a vehicle. The inorganic powder includes SnO-containing glass powder, a refractory filler, and a pigment. The vehicle includes a resin binder and a solvent. Here, content of inorganic powder, a resin binder, and a solvent is 42-52, 8-18, 35-45 by mass ratio. Hereinafter, the reason why the content ratios of the inorganic powder, the resin binder, and the solvent are defined as described above will be described.

  The content ratio of the inorganic powder is 42 to 52 by mass ratio. When the content ratio of the inorganic powder is less than 42, the softening flow of the sealing material layer at the time of laser sealing becomes poor, and the sealing strength tends to be lowered. On the other hand, when the content ratio of the inorganic powder exceeds 52, it is difficult to reduce the thickness of the sealing material layer after firing.

  The content ratio of the resin binder is 8 to 18 by mass ratio. When the content ratio of the resin binder is less than 8, the viscosity of the sealing material paste is difficult to increase, and it is difficult to adjust the viscosity. On the other hand, when the content ratio of the resin binder exceeds 18, the viscosity of the sealing material paste becomes too high, and the printability deteriorates. In addition, the time required for the debinding process becomes longer, and the productivity is lowered.

  The content ratio of the solvent is preferably 35 to 45 by mass ratio. When the content ratio of the solvent is less than 35, the viscosity of the sealing material paste becomes too high, and it becomes difficult to print the paste uniformly. That is, there is a possibility that the layer thickness of the sealing material layer cannot be made constant. Moreover, there exists a possibility that the surface smoothness of a sealing material layer may fall. On the other hand, if the content ratio of the solvent exceeds 45, the viscosity of the sealing material paste becomes too low, and bleeding tends to occur during printing. When bleeding occurs, it becomes difficult to print the sealing material layer in a desired region, and it becomes difficult to make the thickness of the sealing material layer constant. In particular, when the sealing material film is applied and formed in a frame shape, the tendency becomes remarkable at the corner portion.

  Since the sealing material paste according to the embodiment of the present invention contains the inorganic powder, the resin binder, and the solvent in the above ratio, the sealing material layer formed by applying the paste is dried and fired. The layer thickness can be greatly reduced. That is, even if the sealing material paste is applied to a certain extent, the applied film thickness can be reduced by drying the solvent and baking the resin binder. Therefore, even if a screen mask having a general thickness is used at the time of application, the sealing material layer can be formed extremely thin after firing. Moreover, according to the above structures, the viscosity of sealing material paste can be adjusted appropriately and favorable printability and leveling property can be obtained. Therefore, the surface smoothness of the sealing material layer is not impaired after firing.

  Further, when the content of the organic solvent in the sealing material paste increases, it is handled as a dangerous material, and there are restrictions in each process such as manufacturing, supplementation, and transportation. Therefore, the content ratio of the solvent is more preferably less than 40 by mass ratio.

  Further, the sealing material paste according to the present invention preferably has an inorganic powder / vehicle value of 0.7 to 1.1 in terms of mass ratio. If the value of the inorganic powder / vehicle is less than 0.7, the viscosity of the sealing material paste becomes too low, and bleeding tends to occur during printing. Further, the separation of the plate at the time of transferring the sealing material paste to the glass substrate by screen printing deteriorates, and the surface roughness of the sealing material layer after printing tends to increase. On the other hand, when the value of the inorganic powder / vehicle is larger than 1.1, the viscosity of the sealing material paste becomes too high, the coating film thickness varies during printing and the leveling property of the coating film decreases. That is, the surface roughness of the sealing material layer after printing tends to increase.

Next, the configuration of the inorganic powder contained in the sealing material paste will be described in detail. SnO-containing glass powder contained in the inorganic powder, as a glass composition, in mol%, SnO 35 to _70%, preferably contains _P 2 O 5 _10~30%. The reason for limiting the glass composition range as described above will be described below. In addition, in description of the content range of each component,% display points out mol% except the case where there is particular notice.

  SnO is a component that lowers the melting point of glass, and its content is preferably 35 to 70%, 40 to 70%, and particularly preferably 50 to 68%. If the SnO content is 50% or more, the glass powder is softened and flowed easily during laser sealing. When the content of SnO is less than 35%, the viscosity of the glass becomes too high, and it becomes difficult to perform laser sealing with a desired laser output. On the other hand, if the SnO content is more than 70%, vitrification becomes difficult.

P ₂ O ₅ is a glass-forming oxide and is a component that increases the thermal stability of glass. The content is preferably 10 to 30%, 15 to 27%, particularly preferably 15 to 25%. When the content of P ₂ O ₅ is less than 10%, the thermal stability of the glass tends to be lowered. On the other hand, when the content of P ₂ O ₅ is more than 30%, reduces the weather resistance of the glass, it becomes difficult to ensure long-term reliability of the organic EL device or the like.

  In addition to the above components, for example, the following components may be added.

  ZnO is an intermediate oxide and a component that stabilizes the glass. The content is preferably 0 to 30%, 1 to 20%, particularly preferably 1 to 15%. When there is more content of ZnO than 30%, the thermal stability of glass will fall easily.

B ₂ O ₃ is a glass-forming oxide, a component that stabilizes the glass, and a component that enhances the weather resistance of the glass. The content is preferably 0 to 20%, 1 to 20%, particularly preferably 2 to 15%. If the content of B ₂ O ₃ is more than 20%, the viscosity of the glass becomes too high, and it becomes difficult to perform laser sealing with a desired laser output.

Al ₂ O ₃ is an intermediate oxide, a component that stabilizes the glass, and a component that lowers the thermal expansion coefficient of the glass. The content is preferably 0 to 10%, 0.1 to 10%, particularly preferably 0.5 to 5%. When the content of Al ₂ O ₃ is more than 10%, the softening temperature of the glass powder is unduly increased, and it becomes difficult to perform laser sealing with a desired laser output.

SiO ₂ is a glass-forming oxide and is a component that stabilizes the glass. The content is preferably 0 to 15%, particularly preferably 0 to 5%. When the content of SiO ₂ is more than 15%, the softening temperature of the glass powder rises unreasonably and it becomes difficult to perform laser sealing with a desired laser output.

Li ₂ O is a component that lowers the melting point of glass, and its content is preferably 0 to 5%. The content of Li 2 _O is more than 5%, the thermal stability of the glass tends to decrease. Na ₂ O is a component that lowers the melting point of glass, and its content is preferably 0 to 10%, particularly preferably 0 to 5%. When the content of Na 2 _O is greater than 10%, thermal stability of the glass tends to decrease. K ₂ O is a component that lowers the melting point of glass, and its content is preferably 0 to 5%. When the content of K 2 _O is more than 5%, the thermal stability of the glass tends to decrease.

MgO + Ta ₂ O ₅ + MoO ₃ + WO ₃ is a component that increases the thermal stability of the glass, and its content is preferably 0 to 10%, particularly preferably 0 to 5%. If the content of MgO + Ta ₂ O ₅ + MoO ₃ + WO ₃ is more than 10%, the softening temperature of the glass powder rises unreasonably, making it difficult to perform laser sealing with a desired laser output. The contents of MgO, Ta ₂ O ₅ , MoO ₃ , and WO ₃ are each preferably 0 to 5%. Here, “MgO + Ta ₂ O ₅ + MoO ₃ + WO ₃ ” refers to the total amount of MgO, Ta ₂ O ₅ , MoO ₃ , and WO ₃ .

  BaO is a component that enhances the thermal stability of the glass, and its content is preferably 0 to 10%. When there is more content of BaO than 10%, the component balance of a glass composition will be impaired and it will become easy to devitrify glass conversely.

La ₂ O ₃ is a component that enhances the thermal stability of the glass and is a component that enhances the weather resistance of the glass. The content is preferably 0 to 15%, 0 to 10%, particularly preferably 0 to 5%. When the content of La ₂ O ₃ is more than 15%, batch cost soars.

In ₂ O ₃ is a component that enhances the thermal stability of the glass, and its content is preferably 0 to 5%. When the content of In ₂ O ₃ is more than 5%, the batch cost increases.

F ₂ is a component to lower the melting point of the glass, the content thereof is preferably 0 to 5%. When the content of F ₂ is greater than 5%, the thermal stability of the glass tends to decrease.

  In addition to the above components, other components (CaO, SrO, etc.) can be added, for example, up to 10%.

  It is preferable that SnO containing glass powder does not contain PbO substantially from an environmental viewpoint. Here, “substantially no PbO” refers to the case where the content of PbO in the glass composition is 1000 ppm (mass) or less.

  It is preferable that SnO containing glass powder does not contain a transition metal oxide substantially. If it does in this way, it will become difficult to reduce the thermal stability of glass. Here, “substantially no transition metal oxide” refers to the case where the content of the transition metal oxide in the glass composition is 3000 ppm (mass) or less, preferably 1000 ppm (mass) or less.

  The maximum particle diameter D99 of the SnO-containing glass powder is preferably 10 μm or less, particularly preferably 7 μm or less. If it does in this way, the softening temperature of the outermost surface of an application layer can fall, and the softening fluidity | liquidity of an application layer can be improved. As a result, the surface smoothness of the sealing material layer is improved, the time required for laser sealing is shortened, and even if the difference in thermal expansion coefficient between the sealing material layer and the glass substrate is large, the sealing portion or glass Cracks are less likely to occur on the substrate.

The inorganic powder according to the present invention preferably further contains a refractory filler. In this way, the thermal expansion coefficient and mechanical strength of the sealing material layer can be increased. Zircon, zirconia, tin oxide, quartz, β-spodumene, cordierite, mullite, quartz glass, β-eucryptite, β-quartz, zirconium phosphate, zirconium phosphate tungstate, zirconium tungstate as refractory filler , Compounds having a basic structure of [AB ₂ (MO ₄ ) ₃ ] such as NbZr (PO ₄ ) ₃ , A: Li, Na, K, Mg, Ca, Sr, Ba, Zn, Cu, Ni, Mn, etc. B: Zr, Ti, Sn, Nb, Al, Sc, Y, etc., M: P, Si, W, Mo, etc., or solid solutions thereof can be used, but zirconium phosphate is particularly effective in reducing the thermal expansion coefficient. Zirconium tungstate phosphate and NbZr (PO ₄ ) ₃ are preferable. In addition, it is preferable that the content ratio of SnO containing glass and a refractory filler in inorganic powder is G / F: 90 / 10-50 / 50 by volume ratio.

  The maximum particle size D99 of the refractory filler is preferably 5 μm or less, particularly preferably 3 μm or less. If it does in this way, the surface smoothness of a sealing material layer can be improved. In particular, when the average thickness of the sealing material layer is 8 μm or less, the effect becomes remarkable.

The pigment contained in the inorganic powder is preferably an inorganic pigment, and is selected from carbon, Co ₃ O ₄ , CuO, Cr ₂ O ₃ , Fe ₂ O ₃ , MnO ₂ , SnO, and Ti _n O _2n-1 (n is an integer). One type or two or more types are more preferable, and carbon is particularly preferable. These pigments have excellent color developability and good laser absorptivity. As carbon, amorphous carbon or graphite is preferable. These carbons have a property that the average particle diameter D50 of primary particles can be easily processed to 1 nm to 100 nm.

  The pigment content is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.8% by mass. When there is too little content of a pigment, it will become difficult to convert the light of a laser into heat energy. On the other hand, if the pigment content is too large, the sealing material layer becomes difficult to soften and flow during laser sealing, and it becomes difficult to increase the sealing strength.

  The average particle diameter D50 of the primary particles of the pigment is preferably 1 to 100 nm, 3 to 70 nm, 5 to 60 nm, particularly 10 to 50 nm. If the average particle diameter D50 of the primary particles of the pigment is too small, the pigments tend to aggregate together, making it difficult to disperse the pigment uniformly, and the sealing material layer does not soften and flow locally during laser sealing. There is a fear. On the other hand, even if the average particle diameter D50 of the primary particles of the pigment is too large, the pigment is difficult to disperse uniformly, and the sealing material layer may not be locally softened and flowed during laser sealing.

  The pigment preferably contains substantially no Cr-based oxide from the environmental viewpoint. Here, “substantially free of Cr-based oxide” refers to a case where the content of Cr-based oxide in the pigment is 1000 ppm (mass) or less.

  In the inorganic powder according to the present invention, the softening temperature is preferably 450 ° C. or lower, 420 ° C. or lower, and particularly preferably 400 ° C. or lower. When the softening temperature is higher than 450 ° C., the efficiency of laser sealing tends to decrease. The lower limit of the softening temperature is not particularly limited, but it is preferable to limit the softening temperature to 300 ° C. or higher in consideration of the thermal stability of the SnO-containing glass powder. Here, the “softening temperature” refers to a value measured with a macro-type differential thermal analysis (DTA) apparatus in a nitrogen atmosphere, DTA starts measurement from room temperature, and the rate of temperature rise is 10 ° C./min. . In addition, the softening temperature measured with the macro type | mold DTA apparatus points out temperature Ts of the 4th bending point shown in FIG.

  Next, the configuration of the vehicle included in the sealing material paste will be described in detail.

  The vehicle used for the sealing material paste of the present invention preferably contains a plurality of types of resin binders having different molecular weights, and more preferably the components of those resin binders are the same. When reducing the average thickness of the sealing material layer, it is necessary to reduce the content of the inorganic powder in the sealing material paste. However, when the content of the inorganic powder is reduced, the viscosity of the sealing material paste is lowered, and the printability is easily lowered. As a result, the surface roughness of the sealing material layer increases, and it becomes difficult to perform laser sealing at a low output. Therefore, when multiple resin binders with different molecular weights are used, especially when a high molecular weight resin binder is used in combination, the viscosity of the sealing material paste is adjusted even if the content of the inorganic powder in the sealing material paste is reduced. It becomes easy. Further, when a plurality of resin binders of the same kind are used, it becomes easier to adjust the viscosity of the sealing material paste.

  As the resin binder contained in the vehicle, for example, an aliphatic polyolefin carbonate, particularly polyethylene carbonate or polypropylene carbonate can be used. These resin binders are suitable as a raw material for the sealing material paste of the present invention because they have the characteristic that it is difficult to alter the SnO-containing glass powder during binder removal or laser sealing. Moreover, those number average molecular weights are 50000-500000, Especially 80000-300000 are preferable. If it does in this way, it will become easy to optimize the viscosity of sealing material paste.

  Examples of the solvent contained in the vehicle include N, N′-dimethylformamide, ethylene glycol, dimethyl sulfoxide, dimethyl carbonate, propylene carbonate, butyrolactone, caprolactone, N-methyl-2-pyrrolidone, phenyl diglycol (PhDG ), Dibutyl phthalate (DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG), and it is preferable to include one or more selected from these. These solvents have the characteristic that it is difficult to alter the SnO-containing glass powder during binder removal or laser sealing. In particular, among these solvents, one or two selected from propylene carbonate, phenyl diglycol (PhDG), dibutyl phthalate (DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG). The above is preferable. The boiling point of these solvents is 240 ° C. or higher. For this reason, when these solvents are used, it becomes easy to suppress the volatilization of the solvent during application work such as screen printing, and as a result, the sealing material paste can be used stably for a long period of time. . Furthermore, phenyl diglycol (PhDG), dibutyl phthalate (DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG) have high affinity with pigments. For this reason, even if the addition amount of these solvents is small, the situation where a pigment separates in the sealing material paste can be suppressed.

The sealing material paste of the present invention is preferably subjected to a binder removal treatment (firing treatment) in an inert atmosphere. Here, the “inert atmosphere” includes a neutral gas atmosphere such as an N ₂ gas atmosphere and an Ar gas atmosphere, and a reduced pressure atmosphere such as a vacuum atmosphere. Among these, an N ₂ atmosphere is particularly preferable. If it does in this way, it will become easy to prevent the situation which SnO containing glass powder changes in the case of binder removal.

The sealing material paste of the present invention is preferably used for laser sealing in an inert atmosphere. In particular, it is preferably used for laser sealing in an N ₂ atmosphere. If it does in this way, it will become easy to prevent the situation which SnO containing glass powder changes in the case of laser sealing.

  The sealing material paste described above can be satisfactorily applied to an object to be sealed such as a glass substrate by using the sealing material paste application method of the present invention. In the method for applying the sealing material paste of the present invention, it is preferable to use a screen printing method.

  When screen printing is performed by the method for applying the sealing material paste of the present invention, the attack angle of the squeegee is preferably 50 to 70 °. The attack angle is an angle formed by the glass substrate surface and the squeegee front surface. If the attack angle of the squeegee is less than 50 °, the sealing material paste easily wraps around the back surface of the screen mask during printing, causing bleeding and making it difficult to form a precise frit pattern. When the attack angle of the squeegee is larger than 70 °, the squeegee is less bent and the paste is not sufficiently pushed out, so that the printing tends to be faint and uniform application may be difficult.

  The squeegee feed speed is preferably 30 to 80 mm / s. When the feeding speed of the squeegee is less than 30 mm / s, the sealing material layer tends to be thick. On the other hand, when the feed speed of the squeegee is faster than 80 mm / s, blurring of printing and vertical stripes are likely to occur.

  In the sealing material paste coating method of the present invention, the mesh number of the screen mask is preferably 325 to 500. When the mesh number of the screen mask is smaller than 325 (coarse), the sealing material layer tends to be thick. On the other hand, when the mesh number of the screen mask is larger than 500 (fine), the separation of the sealing material paste is deteriorated, and there is a possibility that uniform application becomes difficult.

  The emulsion thickness of the screen mask is preferably 1 to 20 μm. When the emulsion thickness is less than 1 μm, the sealing material paste is difficult to be transferred to the substrate, and there is a possibility that a portion that cannot be printed partially occurs. On the other hand, if the emulsion thickness is larger than 20 μm, the film thickness becomes too large and it becomes difficult to make the sealing material layer after baking thin. In addition, bleeding may occur or the resolution of the coating pattern may become too low, making it difficult to apply the sealing material paste to a desired region.

  If the sealing material paste according to the present invention is screen-printed under the above conditions, the sealing material paste can be satisfactorily applied to the glass substrate.

  The glass substrate with a sealing material layer of the present invention is characterized in that the average thickness of the sealing material layer in a wet state immediately after applying the sealing material paste to the glass substrate is 20 μm or less. Further, the sealing material layer in a wet state is dried, and the average thickness of the sealing material layer in a dry state in which the solvent is volatilized is 10 μm or less. If it does in this way, the thickness of the sealing material layer after baking can be made small easily.

  The glass substrate with a sealing material layer preferably has a surface roughness (Ra) of the sealing material layer of 1.1 μm or less, 0.8 μm or less, 0.6 μm or less, particularly 0.5 μm or less. If it does in this way, the adhesiveness of a sealing material layer and a glass substrate can be improved.

  The glass substrate with the sealing material layer preferably has a surface roughness (RMS) of the sealing material layer of 1.7 μm or less, 1.3 μm or less, 1.0 μm or less, particularly 0.8 μm or less. If it does in this way, the adhesiveness of a sealing material layer and a glass substrate can be improved.

Moreover, a non-alkali glass substrate (for example, OA-10G manufactured by Nippon Electric Glass Co., Ltd.) is usually used for the glass substrate for organic EL devices. The coefficient of thermal expansion of the alkali-free glass substrate is usually 40 × 10 ⁻⁷ / ° C. or less. When sealing alkali-free glass substrates together, it is necessary to match the thermal expansion coefficient of the sealing material layer with the alkali-free glass substrate. For this purpose, it is necessary to increase the content of the refractory filler in the inorganic powder, but the softening fluidity of the sealing material paste is lowered. Therefore, if the average thickness of the sealing material layer is regulated to 5 μm or less, the amount of thermal strain in the glass substrate at the time of laser sealing can be reduced, so the difference in thermal expansion coefficient between the sealing material layer and the glass substrate is large. However, cracks and the like hardly occur in the sealed portion and the glass substrate.

  The sealing material paste and the glass substrate with a sealing material according to the present invention are suitable for use in an organic EL device. Here, the “organic EL device” includes an organic EL display, organic EL lighting, and the like.

Various lasers can be used for laser sealing of the sealing material paste and the glass substrate with the sealing material according to the present invention. In particular, a semiconductor laser, a YAG laser, a CO ₂ laser, an excimer laser, an infrared laser, and the like are preferable in terms of easy handling.

  The present invention will be described in detail based on examples. However, the following examples are merely illustrative. The present invention is not limited to the following examples.

SnO-containing glass powder was prepared as follows. First, after preparing the raw materials so as to have a predetermined glass composition (mol%, SnO 59%, P ₂ O ₅ 20%, ZnO 5%, B ₂ O ₃ 15%, Al ₂ O ₃ 1%), This prepared raw material was put in an alumina crucible and melted at 900 ° C. for 1 to 2 hours under a nitrogen atmosphere. Next, the obtained molten glass was formed into a film shape with a water-cooled roller. Subsequently, the glass film was pulverized by a ball mill and classified to obtain SnO-containing glass powder. The density of the obtained SnO-containing glass powder was 3.88 g / cm ³ .

  Zirconium phosphate powder was used as a refractory filler.

  Ketjen black (graphite) was used as the pigment. The average particle diameter D50 of the primary particles of the pigment was 20 nm. The content of the pigment in the sealing material paste was 0.25% by mass.

  The particle sizes of the SnO-containing glass powder, the refractory filler, and the pigment are values measured on a volume basis by a laser diffraction particle size distribution meter.

  Table 1 shows examples (samples A and B) and comparative examples (sample C) of the present invention.

<Image of Table 1>
First, an inorganic powder and a vehicle (including a resin binder and a solvent) were kneaded with a three-roll mill until the mass ratio shown in the table was uniform, to prepare a sealing material paste. As the resin binder, two types of polyethylene carbonate (hereinafter referred to as PEC) having different molecular weights were used. The number average molecular weight of one PEC was 130,000, and the number average molecular weight of the other PEC was 230,000. As the solvent, propylene carbonate (hereinafter referred to as PC) and phenyl diglycol (hereinafter referred to as PhDG) were used. Note that PC / PhDG was prepared at a mass ratio of 90/10. Moreover, PEC / (PC + PhDG) was adjusted to 25/75 by mass ratio.

  Next, a screen having a thickness of 20 μm and a width of 0.6 mm is applied to the peripheral part of a glass substrate (OA-10G manufactured by Nippon Electric Glass Co., Ltd.) having a length of 200 mm × width of 200 mm × thickness of 0.5 mm. It was applied in a frame shape with a printing machine to form a wet sealing material layer. As the screen mask, a stainless steel mesh having the number of meshes shown in Table 1 and an emulsion thickness of 5 μm was used. The squeegee was made of urethane having an altitude of 90 at the angles and speeds shown in Table 1.

  Subsequently, the glass substrate on which the sealing material paste was screen-printed as described above was dried at 85 ° C. for 5 minutes in an air atmosphere to obtain a dry state. Thereafter, further firing in a nitrogen atmosphere at a temperature of 480 ° C. for 10 minutes, firing the resin binder in the sealing material paste (debinding treatment), and fixing the sealing material paste to the glass substrate, A glass substrate with a sealing material layer was obtained.

  In the production process of the glass substrate with the sealing material layer, the average thickness was measured for the wet state, the dry state, and the sealing material layer after firing. The average thickness of the sealing material layer is a value measured with a non-contact type laser film thickness meter.

  Moreover, the surface state of the sealing material layer after baking was evaluated. Specifically, the surface roughness (Ra, RMS) of the sealing material layer after firing is measured with a surface roughness meter, the surface roughness Ra is 1.1 μm or less, and the surface roughness RMS is “○” for samples that were 1.7 μm or less, “×” for samples whose surface roughness Ra was greater than 1.1 μm, or whose surface roughness RMS was greater than 1.7 μm, the surface condition was evaluated.

As apparent from Table 1, Samples A and B, which are examples of the present invention, were able to reduce the thickness of the sealing material layer after firing to a thickness of 5 μm or less. On the other hand, Sample C, which is a comparative example, could not make the thickness of the sealing material layer after firing 5 μm or less. Samples A and B were evaluated as “◯” for the surface state of the sealing material layer after firing, and a smooth surface could be obtained. On the other hand, Sample C was evaluated as “x” for the surface state of the sealing material layer after firing, and a smooth surface could not be obtained.

  In addition to organic EL devices such as organic EL displays and organic EL lighting, the sealing material of the present invention can be used for laser sealing of solar cells such as dye-sensitized solar cells, laser sealing of lithium ion secondary batteries, and MEMS. It is also suitable for laser sealing of packages.

Claims (10)

A sealing material paste containing an inorganic powder and a vehicle,
The inorganic powder includes at least a glass powder and a pigment,
The vehicle includes a resin binder and a solvent,
The sealing material paste, wherein the contents of the inorganic powder, the resin binder, and the solvent are 42 to 52, 8 to 18, and 35 to 45, respectively, in mass ratio. The inorganic powder further includes a refractory filler,
The sealing material paste according to claim 1, wherein the maximum particle size D99 of the refractory filler is 3 µm or less.   The sealing material paste according to claim 1, wherein the inorganic powder / vehicle value is 0.7 to 1.1 in terms of mass ratio.   The sealing material paste according to any one of claims 1 to 3, wherein the vehicle includes a plurality of types of resin binders having different molecular weights.   The sealing resin paste according to any one of claims 1 to 4, wherein the resin binder is an aliphatic polyolefin carbonate and has a number average molecular weight of 50,000 to 500,000. The SnO-containing glass powder contains, as a glass composition, mol%, SnO 35 to 70%, P ₂ O ₅ 10 to 30%, and the maximum particle diameter D99 of the SnO-containing glass powder is 10 μm or less. The sealing material paste according to any one of claims 1 to 5.   The sealing material paste according to any one of claims 1 to 6, wherein the pigment is amorphous carbon or graphite, and an average particle diameter D50 of primary particles thereof is 1 nm to 5 µm. A sealing material paste application method for applying the sealing material paste according to any one of claims 1 to 7 to a glass substrate by a screen printing method,
The mesh number of the screen mask used for the screen printing method is 325 to 500,
The emulsion thickness of the screen mask used in the screen printing method is 1 to 20 μm,
The attack angle of the squeegee used in the screen printing method is 50 to 70 °,
The method for applying a sealing material paste, wherein a feeding speed of the squeegee is 30 to 80 mm / s. In a glass substrate with a sealing material layer formed by applying the sealing material paste according to any one of claims 1 to 7 to a glass substrate,
A glass substrate with a sealing material layer, wherein an average thickness of the sealing material layer in a wet state immediately after applying the sealing material paste to the glass substrate is 20 μm or less. In a glass substrate with a sealing material layer formed by applying the sealing material paste according to any one of claims 1 to 7 to a glass substrate,
A glass substrate with a sealing material layer, wherein an average thickness of the sealing material layer in a dry state in which the solvent is dried after the sealing material paste is applied to the glass substrate is 10 μm or less.