Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
  • C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
  • C03C8/08—Frit compositions, i.e. in a powdered or comminuted form containing phosphorus
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C27/00—Joining pieces of glass to pieces of other inorganic material; Joining glass to glass other than by fusing
  • C03C27/06—Joining glass to glass by processes other than fusing
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/12—Silica-free oxide glass compositions
  • C03C3/16—Silica-free oxide glass compositions containing phosphorus
  • C03C3/21—Silica-free oxide glass compositions containing phosphorus containing titanium, zirconium, vanadium, tungsten or molybdenum
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C4/00—Compositions for glass with special properties
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
  • C03C8/24—Fusion seal compositions being frit compositions having non-frit additions, i.e. for use as seals between dissimilar materials, e.g. glass and metal; Glass solders

Definitions

• Provisional Application Serial No. 62/108677 filed on January 28, 2015, of U.S. Provisional Application Serial No. 62/157558, filed on May 6, 2015, and of U.S. Provisional Application No. 62/279106, filed on January 15, 2016, the contents of which are relied upon and
• the present disclosure is directed to glasses suitable as a component in a frit, the glass- based frit and a glass assembly sealed using the glass-based frit.
• glass-based frits suitable for use in very different applications, with very different sealing methods.
• the glass-based frits of the present disclosure share very similar constituents and exhibit similar physical and rheological properties.
• a typical VIG design includes two sealed soda-lime glass sheets with support spacers positioned therebetween.
• the support spacers can be on the order of from about 100 to about 200 micrometers ( ⁇ ) in diameter.
• the basis of the VIG thermal efficiency relies on a vacuum of about 10 "4 Torr established between the two glass sheets.
• long-term hermeticity is needed to maintain this vacuum and thus assure a continued low U- value throughout the window's expected lifetime (up to 20 years, or more).
• This means the seal must exhibit superior corrosion resistance, for example aqueous durability, to withstand environmental agents such as water or salt, as well as provide excellent adhesion and mechanical strength to withstand long term mechanical stresses.
• the glass used in VIG assemblies may be thinner than other non-VTG window assemblies, for example in a range from about 2 millimeters to about 3 millimeters.
• thinner glass thicknesses for VIG assemblies may require the soda-lime glass sheets be thermally-tempered. This, in turn, requires that sealing of the glass sheets be accomplished at a temperature typically not exceeding about 400°C to avoid stress relief in the tempered assemblies.
• CTE coefficient of thermal expansion
• VIG assemblies typically do not contain heat sensitive
• VIG sub-assembly comprising glass substrates in contact with frit sealing material disposed therebetween can be heated in an oven, for example, at a suitable sealing temperature and for a sufficient time to seal the glass substrates via the frit without fear of damaging sensitive components.
• OLED organic light emitting diode
• sealing methods for OLED devices may differ substantially from those suitable for VIG sealing
• the temperature sensitivity of the organic material comprising the electroluminescent component of the OLED material limits process temperatures to less than about 125°C, and more conservatively to temperatures not exceeding 100°C.
• the frit employed for sealing an OLED device is typically sealed with a laser that irradiates only the frit positioned between the glass substrates without heating the organic electroluminescent material above the damage threshold.
• low temperature frits i.e., frits with low T g
• T g low temperature frits
• pre-sintering refers to an initial heating of a frit deposited on a glass substrate to adhere the frit to the substrate, for example prior to placing the opposing glass substrate in position on the frit wall formed in the pre-sintering step and the sealing the the substrates together by exposing the pre-sintered frit wall to a laser beam with sufficient optical power at an appropriate wavelength. Because pre-sintering can be performed prior to the inclusion of organic material in the glass package, pre-sintering can be performed in an oven, even for the eventual manufacture of an OLED device.
• the predictor of sealing temperature for a glass frit is glass transition temperature (T g ), which is the temperature of the glass during heating at which the glass structure first becomes capable of motion and relaxation at the atomic level. Accordingly, development of glass-based frits for OLED device sealing has been directed toward achieving a consistently lower glass transition temperature while maintaining other key attributes (especially aqueous durability) at acceptable levels.
• glasses suitable for use as a component in a frit and a glass assembly sealed using the frit.
• the glasses belong to families of vanadium phosphate glasses, and in various embodiments may be lead and/or antimony and/or barium free.
• Uses include but are not limited to a sealing material for sealing vacuum insulated glazing, e.g., thermal windows, and organic light emitting diode devices, e.g., display devices. Frit pastes are also disclosed.
• an antimony free glass comprising the following oxides in mole percent is disclosed:
• T g a glass transition temperature T g equal to or less than 330°C.
• the sum of P 2 Os + Te0 2 may be in a range from about 20 mole % to about 40 mole %, for example in a range from about 25 mole % to about 30 mole %.
• the sum of Fe 2 0 3 and Bi 2 0 3 may be in a range from about 15 mole % to about 30 mole %, for example in a range from about 20 mole % to about 25 mole %.
• a crystallization onset temperature T x of the glass can be in a range from about 440°C to about 455°C.
• the antimony free glass may comprise in mole % on an oxide basis:
• a glass transition temperature T g equal to or less than 310°C, for example the T g may be in a range from about 295°C to about 305°C.
• the sum in mole % of P2O5 + Te0 2 can be in a range from about 25 mole % to about 35 mole %, for example in a range from about 25 mole % to about 32.5 mole %.
• the sum in mole % of Fe 2 0 3 and B12O 3 may be in a range from about 15 mole % to about 25 mole %, for example in a range from about 17.5 mole % to about 25 mole %, for example in a range from about 17.5 mole % to about 20 mole %.
• a crystallization onset temperature T x of the glass can be in a range from about 443°C to about 452°C.
• the sum in mole % of V2O5 + P2O5 + B2O 3 divided by the sum in mole % of Fe 2 0 3 + B12O 3 is equal to or less than about 4.33, for example equal to or less than about 3.6, for example in a range from about 2.5 to about 3.25.
• a glass frit paste comprising a glass frit formed with a glass comprising in mole % on an oxide basis:
• T g a glass transition temperature T g equal to or less than 310°C.
• the glass frit may comprise a particle size distribution with a D 50 in a range from about 10 ⁇ to about 15 ⁇ .
• the glass frit paste may further comprise a binder material in an amount from about 0.48 weight % to about 0.63 weight %.
• the sintered frit Upon sintering in air at 375°C for one hour to form a sintered frit, the sintered frit exhibits no cracking.
• a glass assembly comprising first and second glass plates sealed with a frit seal to form an interior space, wherein a glass of the frit seal is a lead and antimony free glass comprising in mole % on an oxide basis:
• T g a glass transition temperature T g equal to or less than about 310°C.
• At least one of the first and second glass plates may comprise soda-lime glass.
• the glass assembly may comprise a pressure within the interior space that is less than a pressure of an ambient pressure outside the glass assembly.
• the glass assembly may comprise vacuum insulated glazing.
• the glass assembly can be positioned within a wall of a building structure as a window.
• a glass comprising the following oxides in mole percent:
• a T g of the glass is equal to or less than 330°C.
• the glass may comprise in mole % on an oxide basis:
• a T g of the glass is equal to or less than 307°C.
• the T g may be in a range from about 295°C to about 307°C.
• the sum in mole % of P2O5 + Te0 2 can be in a range from about 25 mole % to about 35 mole %, for example in a range from about 25 mole % to about 32.5 mole %.
• the sum in mole % of Fe 2 0 3 and B12O 3 is in a range from about 15 mole % to about 17.5 mole %.
• a crystallization onset temperature T x of the glass can be in a range from about 443°C to about 452°C.
• the sum in mole % of V2O5 + P2O5 + B2O 3 divided by the sum in mole % of Fe 2 0 3 + B12O 3 is equal to or less than about 5.00, for example equal to or less than about 4.00, for example in a range from about 3.00 to about 4.00.
• a glass comprising the following oxides in mole percent:
• a T g of the glass is equal to or less than 305°C.
• the glass may comprise in mole % on an oxide basis:
• a T g equal to or less than 305°C, for example in a range from about 294°C to about 305°C.
• the sum in mole % of P2O5 + Te0 2 can be in a range from about 20 mole % to about 30 mole %, for example in a range from about 25 mole % to about 30 mole %.
• the sum in mole % of Fe 2 03 and B12O 3 can be in a range from about 15 mole % to about 25 mole %, for example in a range from about 17.5 mole % to about 20 mole %.
• the glass may comprise a crystallization onset temperature T x in a range from about 307°C to about 472°C.
• the sum in mole % of V2O5 + P2O5 + B2O 3 divided by the sum in mole % of Fe 2 03 + B12O3 is equal to or less than about 4.67, for example equal to or less than about 3.35, for example in a range from about 2.4 to about 4.67, for example in a range from about 2.4 to about 3.25
• a glass assembly comprising first and second glass plates sealed with a frit seal to form an interior space, wherein a glass of the frit seal is a lead-free glass, the frit seal comprising in mole % on an oxide basis:
• T g of the glass is equal to or less than 307°C
• the glass assembly may comprise an organic light emitting diode.
• an antimony free glass comprising the following oxides in mole percent:
• Te0 2 divided by P 2 Os is in a range from about 0.6 to about 1.6 and Bi 2 0 3 divided by Fe 2 0 3 is in a range from about 0.3 to about 1.5.
• a glass transition temperature T g of the glass is equal to or less than 330°C.
• the antimony free glass comprised in mole % on an oxide basis:
• the glass transition temperature T g of the glass is equal to or less than 310°C.
• FIG. 1 is a perspective view of an example vacuum insulated glazing (VIG) assembly according to embodiments described herein;
• VIP vacuum insulated glazing
• FIG. 2 is a cross sectional side view of an end portion of the VIG assembly of FIG. 1 ;
• FIG. 3 is a cross sectional side view of an end portion of another embodiments of a VIG assembly;
• FIG. 4 depicts a series of photographs ((a) through (d)) showing relative aqueous durability test results for samples of glasses described herein;
• FIG. 5 is a plot of dimensional change in micrometers as a function of temperature in degrees centigrade for a glass sample described herein, and showing the dimensional change from room temperature to about 250°C, and the calculated coefficient of thermal expansion over the temperature range from 50°C to 200°C; and
• FIGS. 6A through 6D are photographs showing the sintering and infiltration performance of four frit paste samples, visually depicting the amount of mud-cracking and infiltration between the glass plates;
• FIG. 7 is a plot showing the change in CTE for two frit paste formulation as a function of temperature
• FIG. 8 is an cross sectional edge view of an exemplary OLED device comprising a glass package
• FIG. 9 is a plot of two frit paste formulations illustrating viscosity change as a function of temperature
• FIG. 10 is an scanning electron microscope (SEM) view of a conventional frit pre- sintered onto a glass substrate
• FIG. 11 is an SEM view of the conventional frit of FIG. 11 after final sintering
• FIG. 12 is an SEM view of a low T g frit according to an embodiment disclosed herein sintered onto a glass substrate;
• FIG. 13 is an SEM view of another low T g frit according to another embodiment disclosed herein sintered onto a glass substrate;
• FIG. 14 is top view of a test seal formed with control frit CI (with 20% ⁇ -quartz filler) following heat treatment at 325°C for 1 hour in air, then presintering at 400°C for lhour in N 2 , and laser- sealing, illustrating the resultant seal width;
• FIG. 15 is a top-down view of a frit seal formed between two glass substrates by sintering a low T g frit according to an embodiment disclosed herein positioned between the substrates, illustrating the resultant seal width;
• FIG. 16 is a top-down view of a frit seal formed between two glass substrates by sintering another low T g frit according to another embodiment disclosed herein positioned between the substrates, illustrating the resultant seal width;
• FIG. 17 is a plot showing analysis results of leached vanadium in supernatant for a control (conventional) frit and a low T g frit in a 90°C beaker test and in a PCT test;
• FIG. 18 is a Weibull plot comparing the failure strength of a frit seal sealing two glass substrates for a conventional frit and an example low T g frit according to an embodiment disclosed herein.
• Ranges can be expressed herein as from “about” one particular value, and/or to "about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
• glasses disclosed herein may be referred to in a substantially solid (bulk form), or in a particulate form that can be produced, for example, by grinding or milling the bulk glass.
• the glass in a particulate form may be referred to as glass frit.
• a frit paste is to be construed to mean a paste made using a glass particulate (glass frit) and having a paste-like constituency.
• typical frit pastes can comprise a vehicle material (e.g., an organic solvent) and/or a binder material (e.g., an organic binder material).
• a frit seal shall be interpreted to mean a glass-containing seal formed with a frit (e.g., frit paste) on at least one glass article, for example a glass plate, by the consolidation (sintering) of the frit.
• a frit paste e.g., frit paste
• the frit paste before sintering may include one or more materials selected to vary the CTE of the bass glass frit.
• frit used in isolation shall refer generically to a glass frit or a frit paste made with the particulate glass.
• glass-based frits suitable for use in different applications, with different sealing methods.
• the glass-based frits of the present disclosure derive from the same family of vanadium-phosphate glasses, and may be selected as appropriate from that family to meets the needs of the specific application. Accordingly, disclosed herein are glasses belonging to the family comprising the compositional ranges described in Table 1 below. Ranges are described in mole % on an oxide basis.
• the glass-based frit may further contain Li0 2 in some embodiments.
• the sum of P 2 Os and Te0 2 can be in a range from about 20 mole % to about 40 mole %, for example in a range from about 20 mole % to about 35 mole %.
• the sum in mole % of Fe 2 C>3 and Bi 2 C>3 can be in a range from about 20 mole % to about 30 mole %.
• Frit glasses may be selected from the foregoing compositional ranges for such diverse applications as sealing VIG assemblies utilizing oven sintering, or sealing OLED assemblies using laser sealing methods.
• the frit glasses may be combined with one or more solvents and one or more binder materials to produce a frit paste with suitable rheological properties.
• the frit paste may further contain a dispersant and may still further include one or more filler materials selected to modify a CTE of the frit seal upon sintering.
• a VIG assembly 10 in accordance with certain embodiments described herein and as shown in FIG. 1 comprises a first glass plate 12, a second glass plate 14 and a frit seal 16.
• VIG assembly 10 may further comprise a pump-out tube 18 used to obtain a vacuum within an interior space 20 (see FIGS. 2, 3) between the first and second glass plates 12, 14 and the frit seal 16.
• pump-out tube 18 may be connected with a vacuum source, such as a pump, and atmosphere within the interior space 20 can be at least partially removed to produce a pressure in the interior space lower than an ambient atmosphere outside the interior space, for example a full or partial vacuum, after which the pump-out tube may be sealed.
• VIG assembly 10 may still further comprise spacers 22 positioned between the first and second glass plates 12, 14 within interior space 20. Spacers 22 aid in maintaining uniform separation between the first and second glass plates and add rigidity to the VIG assembly.
• Second glass plate 14 may be shorter than first glass plate 12 in at least one dimension so that first glass plate 12 extends beyond second glass plate 14 in the at least one dimension.
• Frit seal 16 is formed by a glass frit typically formed into a frit paste by the addition of further components, such as a solvent, a binder and optionally a dispersant, and applied to edges of the first and second glass plates with the spacers positioned between the glass plates, thereby allowing the frit paste to infiltrate between the glass plates and wet interior faces of the glass plates.
• a filler material for example a CTE-modifying filler material, may also be added.
• the frit paste may further wet a portion of a face of the first or second glass plate, and an edge of the first or second glass plate, as illustrated in FIG. 2, thereby forming a fillet.
• the first and second glass plates may be of equal size and/or aligned, such as one over the other, whereby the frit paste can infiltrate between the first and second glass plates and wet at least a portion of the interior surfaces of both glass plates, and also wet the edges of both glass plates.
• the frit seal can constitute a contiguous seal that seals between the glass plates and over at least one edge of one or both of the glass plates 12, 14.
• VIG assembly 10 may be sealed by heating the assembly, for example in an oven, for a time and at a temperature suitable to burn out any organic materials in the frit paste, for example the solvent and/or binder, and to sinter the glass frit to form a solid frit seal that joins the first and second glass plates.
• the interior space 20 may be pumped out to form the vacuum as previously described.
• a family of glass compositions in the V 2 0 5 -P205-Fe 2 0 3 -Bi 2 0 3 -Te0 2 system are disclosed that exhibit a low glass transition temperature (T g ), excellent aqueous durability, air sinterability and, via the addition of a suitable filler material when necessary, a CTE in near-match with soda- lime is obtainable.
• the composition family is suitable for forming a frit paste for sealing glass packages, for example VIG assemblies.
• the major components in this family perform specific roles and determine desired properties of the glass such that glasses according to embodiments described herein, and frits made therefrom, comprise a low T g ; include V2O5 to facilitate a low T g and to promote significant light absorption at wavelengths in the near infrared spectrum to facilitate good laser sealability if desired; include P2O5 for good glass stability (suppression of devitrification), and; exhibit excellent aqueous durability by stabilizing V2O5 using Fe 2 0 3 .
• T g measurement values as described herein were performed using differential scanning calorimetry (DSC) in accordance with ASTM El 356.
• the VIG manufacturing process may employ furnace heating for fusing the frit, in contrast with laser-sealing for OLED devices, the inclusion of V2O5 in any sealing frit composition further aids in achieving a low T g .
• partial replacement of other major components, such as P 2 O 5 and Fe 2 C> 3 were found to be possible without compromising either glass stability or aqueous durability, but resulted in a substantial drop in T g .
• Te0 2 can be used to partially replace P2O5 with no loss of glass stability, but with a substantial drop in T g
• B1 2 O 3 can be used to partially replace Fe 2 0 3 , also with no appreciable loss in aqueous durability but with a substantial drop in T g .
• compositions were discovered within the V 2 05-P 2 05-Fe 2 03 family: i) glasses with partial replacement (up to 15 mole %) of P 2 O 5 by Te0 2 , with only minimal (0 mole % to 5 mole %) partial replacement of Fe 2 0 3 by B1 2 O 3 , and; ii) glasses with partial replacement (up to 15 mole % each) of P 2 O 5 by Te0 2 , and greater partial replacement of Fe 2 0 3 by B1 2 O 3 .
• glasses with Te0 2 greater than about 15 mole % tend to have high CTE (and are expensive from a raw material standpoint), while glasses with B1 2 O 3 greater than 15 mole % tend to crystallize readily to either B1VO 4 or B1PO 4 . Accordingly, glasses disclosed herein may fall within the compositional ranges, expressed on an oxide basis in mole %, presented below in Table 2.
• Table 3 lists example compositions of specific glasses within the composition family of Table 2.
• a conventional frit glass designated CI is also listed. All percentages are in mole percent on an oxide basis. Shown for each glass is T g and T x (in degrees centigrade, °C), with each parameter measured on a fine glass powder sample comprising a particle size distribution with a D 50 in a range from about 1 ⁇ to about 3 ⁇ . Note that the compositions CI , C2 and C3 exhibit a T g that is 30°C to 40°C lower than the conventional CI glass. Shown in FIG.
• suitable frit glass compositions can include V 2 Os in an amount from about
• B 2 0 3 in an amount from about 0 mole % to about 50 mole %, ZnO in a range from about 0 mole
• the composition can also include 0 - 15 mole % Te0 2 , 10 - 15 mole % P 2 Os and 0 - 2.5% Li0 2 .
• Glasses in Tables 3 and 4 can exhibit a ratio of Te0 2 /P 2 0s in a range from about 0.6 to about 1.6 including all ranges and sub-ranges therebetween, for example in a range from about 0.8 to about 1.6. Glasses in Tables 3 and 4 can also exhibit a ratio of Bi 2 0 3 /Fe 2 0 3 in a range from about 0 to about 1.5 including all ranges and sub-ranges therebetween, for example in a range from about 0.15 to about 1.5, for example in a range from about 0.30 to about 1.5, for example in a range from about 0.70 to about 1.5.
• V2O5 content for VIG designated frits may be lower than are possible for good OLED laser frit sealing, discussed later in the present disclosure, T g values rise as V2O5 content falls below about 45 mole % and approaches 40 mole %. While frits with higher T g may be suitable for other sealing applications, their usefulness for VIG sealing is less favored. This increase in T g can be seen with the aid of Table 5, where sealing temperatures of the listed glasses may exceed 400°C. Consequently, cullet testing was anticipated to be indicative of the results for flow button testing and flow button beaker testing (i.e., aqueous durability testing) was not performed for these samples.
• glass compositions described in Table 5 can exhibit sealing temperatures in the neighborhood of 400°C and should not be dismissed as potential glass frit candidates, even for some VIG applications.
• Glasses in Table 5 can exhibit a ratio of Te0 2 /P 2 05 in a range from about 0.8 to about 1.0 including all ranges and sub-ranges therebetween, for example in a range from about 0.9 to about 1.0.
• Glasses in Table 5 can also exhibit a ratio of Bi203/Fe203 in a range from 1.0 to about 1.5 including all ranges and subranges therebetween.
• the aqueous durability test consisted of immersing separately both a piece of cullet and a fired (sintered) flow button of the glass in 90°C deionized water for 48 hours, and then assessing the color of the supernatant.
• the light tint observed for the conventional glass is presumed acceptable, since seals made with a frit paste formed with this glass have survived exposure at 85°C and 85% relative humidity for greater than 1000 hours.
• the new compositions represented in FIG. 4 (flow button) match or exceed the aqueous durability of the conventional glass sample CI .
• the new compositions CI, C2 and C3 can also be adjusted to exhibit excellent CTE compatibility with soda-lime substrate glass, for example with the use of a CTE-modifying filler material.
• thermomechanical analysis of sample C2 (see Table 3) initially as a particulate that was subsequently fired to 380°C for about 1 hour.
• frit compositions suitable for VIG applications may require a filler to assure minimal CTE mismatch with soda-lime glass.
• the filler used for examples described herein was zirconium phosphate, although other fillers such as zirconium tungsten-phosphate, or ⁇ - quartz may also be used.
• the measured CTE of sample C2 was between about 50°C and about 200°C of 8.89 ppm/°C, with a CTE range for the compositional families including samples CI, C2 and C3 expected to fall within a range from about 8.0 ppm/°C to about 9.00 ppm/°C.
• Soda-lime glasses typically exhibit a CTE in a range from about 8.80 ppm/°C to about 9.20 ppm/°C. It should be noted that the CTE depicted in FIG. 5, over the greater range from about room temperature to about 250°C, does not vary significantly from the CTE in the range from 50°C to 200°C.
• VIG frit seal geometries can involve a relatively thick (0.200 millimeter to 0.500 millimeter) frit seal between two sheets of soda-lime glass and comprise a relatively thick external sintered frit or frit fillet for additional mechanical support.
• the frit paste used in forming the frit seal and the fillet is typically pen- dispensed on one or both of the outside edges of the two glass plates, but can also be screen- printed, and is expected to flow and infiltrate between the two glass plates.
• a strong and adherent outside sintered frit e.g., fillet
• This geometry was mimicked in the laboratory by dispensing frit pastes with a syringe dispenser along the outside edge of two soda-lime glass plates separated by a 0.5 millimeter glass spacer.
• a suitable frit paste should flow between the two glass plates when dispensed along the edge and form a well-adhered, defect-free glossy coating with a well- adhered thick outside frit seal when fired.
• Suitable organic binders may include without limitation cellulose (e.g., ethyl cellulose, e.g., T-100, or Dow 200 available from Dow Chemical
• the paste may further include a dispersant, and may also include a filler material. It should also be noted that Theologically, the frit glass chemistry (e.g., glass composition) was largely irrelevant to the paste behavior.
• the binder level should be in a range from about 0.48 weight % to about 0.63 weight % for optimal frit paste infiltration. At binder levels lower than about 0.48 weight %, such as 0.38 weight % for example, frit paste infiltration becomes excessive, while at binder levels in excess of about 0.63 weight %, such as about 0.91 weight % (RFP-3), frit paste infiltration is absent. Binder level was found to be more significant in optimizing frit paste infiltration than solvent level (see for example RFP-3 vs. RFP-12 in Table 6).
• Tables 7-9 describe additional example frit paste formulations.
• FIG. 6A - 6D Shown in FIG. 6A - 6D are examples of different frit paste performance tests used to evaluate sealing in the foregoing simplified facsimile VIG assembly.
• the glass spacer a small glass sheet positioned between the first and second glass plates, can be clearly seen in the RFP-3 (FIG. 6A) and RFP-10 (FIG. 6D) samples.
• the samples were fired to 375°C in air and held at that temperature for lhr.
• Frit pastes RFP-3 and RFP-6 and RFP-8 comprised conventional glass frit CI
• frit pastes RFP-7, and RFP-9 and RFP- 12 comprised glass frit C2.
• the solids loading and particle sizes of the frit pastes were different for the various pastes, as was the binder level and binder molecular weight.
• Frit paste RFP-3 exhibits mud-cracking (caused by excess shrinkage during binder and solvent burn-out), which is undesirable for VIG sealing, as well as little or no frit paste infiltration between the two plates of glass.
• Frit paste RFP-6 (FIG. 6B) exhibits mud-cracking, but also exhibits frit paste infiltration.
• Frit paste RFP-9 (FIG. 6C) does not exhibit mud-cracking, but shows excess paste infiltration.
• frit paste RFP-10 (FIG. 6D) combines the desired attributes of no mud-cracking and acceptable paste infiltration.
• Mud-cracking is an issue that can directly impact fired frit seal strength. Mud-cracking was eliminated in example frits disclosed herein by increasing the frit particle size to a D 50 range from about 10 micrometers to about 15 micrometers from a prior range of about 1 micrometers to about 3 micrometers (RFP-7 vs. RFP-8). Reducing the total organic content of the frit paste while maintaining a fine particle size for the frit paste had no effect in preventing mud-cracking
• the preceding non-Pb glass compositions possess a low T g and can be used to seal VIG assemblies at temperatures substantially lower than Pb-based glass, the current frit material of choice for sealing thermally- insulating windows. These lower glass transition temperatures are needed for thinner VIG assemblies, since they permit the use of tempered soda-lime glass.
• glass compositions disclosed herein may also be free of barium and antimony. Exemplary frit paste formulations described in this disclosure can be used to avoid major process defects such as mud-cracking in the frit seal.
• FIG. 8 illustrates an exemplary OLED device 30 comprising a first glass substrate 32 and a second glass substrate 34 sealed to the first glass substrate by a frit seal 36.
• the OLED device further includes an electroluminescent material and associated electronic components 38 disposed between the first and second glass substrates and sealed therein with frit seal 36.
• the electroluminescent material and associated electronic components may be formed on first glass substrate 32, while the second glass substrate 34 is a cover substrate, which may include a color filter (not shown).
• the frit seal is typically formed by depositing a glass frit, for example via pen dispensing or screen printing, around an edge portion of one or both first and second glass substrates.
• the glass frit e.g., frit paste
• the glass frit may be deposited on the second glass substrate and pre-sintered to the second glass substrate in a furnace or oven.
• the first and second glass substrates may then be positioned in opposing relationship with the pre-sintered frit positioned therebetween.
• a laser may then be used to heat the pre-sintered frit, softening the frit and forming a frit seal that adheres together the first and second substrates.
• the major components in the family of low T g frit glasses perform very specific roles and determine major properties of the frit.
• the components in the frits suitable for use in the sealing of glass packages for OLED devices provide both positive and negative contributions to frit performance.
• V2O5 both lowers T g and increases near infrared absorbance, but on the other hand degrades aqueous durability.
• P2O5 improves glass stability (decreases devitrification tendency), but at the same time raises T g .
• Fe 2 03 stabilizes the vanadium oxidation state, minimizes aqueous attack on vanadium and lowers CTE, but like P2O5, raises T g .
• V2O5 the key component for OLED sealing
• this species provides for both low T g and laser - absorbance necessary during laser sealing processes.
• traditional routes for achieving lower T g such as alkali and/or halide addition, are typically not permitted in OLED frit compositions, since these components could result in poisoning of the TFT (thin film transistor) layer of the active OLED device, one strategy is to incorporate other low T g glass formers into the frit composition.
• a list of inorganic oxides that will form glasses by themselves, or with small amounts of a second component include S1O2, B2O 3 , P2O5, Ge0 2 , B12O 3 , V2O5, Sb 2 03 i
• S1O2 and Ge0 2 may be excluded because of very high T g , while Sb203, and AS2O3 may be undesirable because of environmental concerns.
• V2O5 and P2O5 are already components in the OLED frit, while past work with B2O 3 has shown that additions of this component in amounts greater than about 5 mole % can result in decreased aqueous durability.
• B12O 3 and Te0 2 both of which are low T g glass formers, are favored additions.
• B12O 3 in particular, has the attractive feature that the Bi cation is sesquivalent, and may well play a role in the frit similar to other sesquivalent cations (Sb +3 in Sb 2 03, and Fe +3 in Fe 2 03) in which V2O5 is stabilized by an oxide capable of oxygen loss or reduction.
• T g T g , as measured by differential scanning calorimetry (DSC) in accordance with ASTM E1356, should be no higher than about 310°C for OLED sealing, for example, no higher than about 305°C, for example in a range from about 290°C to about 310°C, for example in a range from about 295°C to about 300°C.
• DSC differential scanning calorimetry
• a piece of cullet heated to 375°C should appear vitreous, without surface devitrification, and should also exhibit evidence of viscous flow, such as rounding of edges.
• a flow button sintered at 380°C should exhibit substantial flow and rounding of edges and remain glossy, without devitrification or oxidation, both by visual inspection and by x-ray diffraction (XRD).
• a flow button sintered at 380°C should exhibit flow and rounding of edges and remain glossy, without evidence of devitrification or oxidation, both by visual inspection and by XRD.
• Aqueous durability (beaker test): The standard beaker test consists of immersing a test sample of the glass in 40 milliliters of deionized water at 90°C for 48 hours, and then visually evaluating the appearance of the supernatant and the condition of the sample after the test.
• a flow button sintered at 380°C should yield a supernatant that is clear to only slightly tinted, and the sample should be intact, without evidence of residue from partial disintegration.
• a flow button sintered at 380°C should yield a supernatant that is clear to only slightly tinted, and the sample should be intact without, evidence of residue from partial disintegration.
• cullet from all glass melts was first evaluated for both as-poured glass stability and stability following heat-treatment at 375°C. If acceptable glass stability (e.g., lack of devitrification) was demonstrated, T g of the cullet was then measured by DSC. If the cullet T g was equal to or less than about 310°C, for example equal to or less than about 300°C, then pieces of the bulk glass were evaluated for aqueous (beaker) durability. Assuming successful performance in this test, the cullet was air jet-milled to a D 50 particle size in a range from about
• compositional ranges (in mole %) described in Table 10 represent glasses in this series with T g equal to or less than about 310°C , for example equal to or less than about 305°C, for example in a range from about 290°C to about 300°C.
• Example compositions (expressed in mole %) are shown in Tables 1 1 and 12. Compositions were obtained (most notably C4) that possessed T g values in the 295-300°C range, and that also exhibited excellent aqueous durability as both cullet and as a fired flow button. These compositions also exhibited good fired flow as a fine powder.
• Tables 11 and 12 below describe compositions with partial replacement (up to 15 mole %) of Te0 2 -for-P 2 0 5 , with only minimal ( ⁇ 5%) partial replacement of Fe 2 0 3 by B12O 3 .
• Table 11 illustrates that for some compositional groupings, e.g., Group ⁇ , Te0 2 should be greater than about 10% for low T g , exemplified by sample C20 containing Te0 2 at 5 mole % and exhibiting a T g of 328°C; but less than 20 mol % for glass stability, as shown by sample C22 having Te0 2 at 20 mole % and exhibited poor flow and significant devitrification.
• glass compositions as described herein may comprise V2O5 in a range from about 45 mole % to about 50 mole % including all ranges and sub-ranges therebetween; P2O5 in a range from about 5 mole % to about 15 mole % including all ranges and sub-ranges
• Glasses in Table 11 can exhibit a ratio of Te0 2 /P 2 0 5 in a range from about 0.3 to about 4.0 including all ranges and subranges therebetween, for example in a range from about 0.3 to about 1.2, for example from about 0.6 to about 1.2, for example from about 1.0 to about 1.2. Glasses in Table 11 can also exhibit a ratio of Bi 2 0 3 /Fe 2 0 3 in a range from 0 to about 0.4 including all ranges and sub-ranges therebetween, for example in a range from 0 to about 0.35.
• Te0 2 should be maintained equal to or less than about 15 mole % to achieve the low T g desired for OLED sealing.
• Examples C25 and C26, with higher T g are less desirable for OLED sealing applications, but may, for example, be applicable to VIG sealing.
• glass compositions as described herein may comprise V2O5 in a range from about 50 mole % to about 52.5 mole % including all ranges and sub-ranges therebetween; P2O5 in a range from about 12.5 mole % to about 17.5 mole % including all ranges and sub-ranges therebetween, for example in a range from about 15 mole % to about 17.5 mole; Fe 2 03 in a range from about 10 mole % to about 17.5 mole % including all ranges and sub-ranges therebetween; B2O 3 in a range from 0 mole % to about 5 mole % including all ranges and sub-ranges therebetween; ZnO in a range from 0 mole % to about 2.5 mole % including all ranges and subranges therebetween; Ti0 2 in a range from 0 mole % to about 5 mole % including all ranges and sub-ranges therebetween; Te0 2 in a range from about 10 mole %
• Glasses in Table 12 can exhibit a ratio of Te0 2 /P 2 05 in a range from about 0.5 to about 1.2 including all ranges and sub-ranges therebetween, for example in a range from about 0.65 to about 1.2, for example in a range from about 0.8 to about 1.2.
• Glasses in Table 5 can also exhibit a ratio of Bi 2 03/Fe 2 03 in a range from 0 to about 1.5 including all ranges and sub-ranges therebetween, for example in a range from about 0.2 to about 0.5, for example in a range from about 0.3 to about 0.5, for example in a range from about 0.4 to about 0.5.
• B12O 3 can only be tolerated at equal to or less than about 5 mole % from a T g standpoint, since 7.5 mole % B12O 3 was found to raise T g to greater than 310°C.
• higher levels of B12O3 can be tolerated from a low T g standpoint in the family of glasses where simultaneous Bi 2 0 3 -for-Fe 2 0 3 and Te0 2 -for-P 2 0 5 substitutions are made. This distinguishes both families of glasses as distinct composition groups.
• compositions (expressed in mole % on an oxide basis) that possessed T g values in the 295-300°C range, and excellent aqueous durability as both cullet and as a fired flow button. These compositions also possessed good fired flow as a fine powder.
• the durability index should be as low as possible (consistent with low T g and other properties such as flow and resistance to devitrification), for example in the range from about 2.0 to about 3.5. Glasses with a durability index in this range were considered acceptable for OLED sealing applications (clear or light tint) in the beaker test. Aqueous durability was appreciably degraded for glasses with durability indices higher than about 3.5, with beaker test results deteriorating from a clear or a light tint to medium tint (e.g., 3.9), and dark and disintegrated (> 4.0).
• such glasses may be acceptable as frit glasses in applications where aqueous durability is unnecessary.
• composition ranges shown in Table 13 exhibit low T g (defined in the context of OLED sealing as having a T g equal to or less than about 310°C), excellent aqueous durability (measured by the 48 hour beaker test) as both cullet and as a fired flow button, and good fired flow as a fine powder at temperatures equal to or less than about 400°C.
• Table 14 describes compositions, in mole % on an oxide basis, with partial replacement of Te0 2 -for-P 2 05 and Bi 2 03-for Fe 2 03.
• the Group VI glasses represent good sealing
• glass compositions as described herein may comprise V 2 O 5 in a range from about 47.5 mole % to about 52.5 mole % including all ranges and sub-ranges therebetween, for example in a range from about 50 mole % to about 52.5 mole %; P2O5 in a range from about 10 mole % to about 17.5 mole % including all ranges and sub-ranges therebetween, for example in a range from about 10 mole % to about 12.5 mole%, for example in a range from about 10 mole % to about 15 mole %, for example in a range from about 12.5 mole % to about 15 mole %, for example in a range from about 12.5 mole % to about 17 mole %, for example in a range from about 15 mole % to about 17.5 mole %; Fe 2 03 in a range
• the durability index in accordance with equation 2 may range, for example, between about 2.8 to about 3.25.
• Glasses in Table 14 can exhibit a ratio of Te0 2 /P 2 05 in a range from about 0.2 to about 2.0 including all ranges and sub-ranges therebetween, for example in a range from about 0.5 to about 2.0, for example in a range from about 1.0 to about 1.6, for example in a range from about 1.0 to about 1.4, for example in a range from about 1.0 to about 1.2.
• Glasses in Table 14 can also exhibit a ratio of Bi 2 03/Fe 2 03 in a range from 1.0 to about 4.0 including all ranges and sub-ranges therebetween, for example in a range from about 1.0 to about 3.0, in a range from about 1.0 to about 2.0, for example in a range from about 1.0 to about 1.2.
• Table 15 describes compositions, in mole % on an oxide basis, with partial replacement of Te0 2 -for-P 2 05 and Bi 2 03-for Fe 2 03.
• Te0 2 should be maintained equal to or less than about 27.5 mole % to obtain good aqueous stability, while for the Group IX glasses the durability index should be less than about 3.4.
• glass compositions as described herein may comprise V2O5 in a range from about 45 mole % to about 55 mole % including all ranges and sub-ranges therebetween, for example from about 45 mole % to about 52.5 mole %; P2O5 in a range from 0 mole % to about 15 mole % including all ranges and sub-ranges therebetween, for example in a range from 0 mole % to about 5 mole %, for example in a range from about 5 mole % to about 15 mole %, for example in a range from about 10 mole % to about 15 mole %; Fe 2 0 3 in a range from about 5 mole % to about 15 mole % including all ranges and sub-ranges therebetween, for example in a range from about 10 mole % to about 15 mole %, for example in a range from about 12.5 mole % to about 15 mole %; B2O3 in a range from 0
• the durability index in accordance with equation 2 may range, for example, between about 2.4 to about 4.67, for example in a range from about 2.4 to about 3.45, for example in a range from about 2.4 to about 2.9.
• Glasses in Table 15 can exhibit a ratio of Te0 2 /P 2 05 in a range from about 0.5 to about 10.0 including all ranges and sub-ranges therebetween, for example in a range from about 0.5 to about 5.0, for example in a range from about 0.5 to about 2.5, for example in a range from about 0.5 to about 1.5.
• Glasses in Table 15 can also exhibit a ratio of Bi 2 0 3 /Fe 2 0 3 in a range from 0.4 to about 2.0 including all ranges and sub- ranges therebetween, for example in a range from about 0.5 to about 1.2, for example in a range from about 0.7 to about 1.2
• Table 16 describes compositions, in mole % on an oxide basis, with partial replacement of Te0 2 -for-P 2 05 and Bi 2 03-for-Fe 2 03.
• V2O5 should be maintained greater than about 40 mole % to obtain low T g and equal to or less than about 55 mole % for aqueous stability.
• glass compositions as described herein may comprise V2O5 in a range from about 40 mole % to about 55 mole % including all ranges and sub-ranges therebetween; P2O5 in a range from about 5 mole % to about 15 mole % including all ranges and sub-ranges therebetween, for example in a range from about 12.5 mole % to about 15 mole %; Fe 2 03 in a range from about 10 mole % to about 12.5 mole % including all ranges and sub-ranges therebetween; B2O 3 in a range from 0 mole % to 5 mole % including all ranges and sub-ranges therebetween; Ti0 2 in a range from 0 mole % to about 5 mole %; ZnO in a range from 0 mole % to about 5 mole %; Te0 2 in a range from about 5 mole % to about 15 mole % including all ranges and sub-ranges therebetween, for example in
• the durability index in accordance with equation 2 may range, for example, between about 2.25 to about 3.25.
• Glasses in Table 16 can exhibit a ratio of Te0 2 /P 2 05 in a range from about 0.4 to about 3.0 including all ranges and subranges therebetween, for example in a range from about 0.4 to about 2.0, for example in a range from about 0.4 to about 2.0, for example in a range from about 0.4 to about 1.2.
• Glasses in Table 16 can also exhibit a ratio of Bi 2 03/Fe 2 03 in a range from 1.0 to about 1.2 including all ranges and sub-ranges therebetween.
• the glass transition temperature determines the temperature needed both for furnace-sealing of assemblies such as VIG devices as well as the top temperature used in the pre-sintering step for OLED devices prior to laser-sealing. Both processes require the frit be well-sintered and without excess porosity or traces of frit grains. This requires a viscosity near the softening point (10 7 6 poise) be attained during the process so that sufficient frit flow occurs for adhesion and densification.
• T g frit 9 illustrates viscosity curves in the softening range obtained by the parallel plate viscometry method (ASTM C1351M) for a low T g frit with T g equal to 299°C, and for the control frit (see either Tables 11 and 12 or 13 through 15) with Tg equal to 331°C. Note that the difference in T g of approximately 30°C between the frits is mirrored almost exactly in the 25°C difference in softening point between the two frits. This means the low T g frit can be processed at a temperature 25 - 30°C lower than the control frit CI .
• FIGS. 10, 1 1 and 12, 13, respectively The direct manifestation of the 25°C difference in softening point seen in FIG. 9 between the control frit glass CI and the low T g composition C3 may be seen in FIGS. 10, 1 1 and 12, 13, respectively, where SEM cross-sections are shown for both compositions following various pre-sintering treatments.
• the control frit CI (including 20 wt. % ⁇ quartz filler) first received an initial heat-treatment at 325°C for 1 hour in air for binder burn-out followed by a higher temperature heat treatment in N 2 at either 380°C (FIG. 10) or 400°C (FIG. 11) to permit actual pre-sintering and initial bonding to the encapsulation (cover) glass substrate.
• the low T g frit C3 (with 20% zirconium phosphate filler) received only a single heat treatment at either 360°C (FIG. 12) or 380°C (FIG. 13), in air, with no lower temperature burn-out hold used.
• FIG. 14 shows a picture of a portion of a sealed device made with the control frit CI that contained 20 % by weight of ⁇ -quartz filler to lower CTE.
• the screen- printed frit Prior to laser-sealing, the screen- printed frit was pre-sintered in a two-step process: from room temperature to 325°C for a 1 hour temperature hold in air for binder burn-out, followed by heating to 400°C in N 2 for 1 hour for actual pre-sintering and initial bonding to the encapsulation glass.
• the percent seal width (defined as seal width/total width of frit) obtained by laser sealing the device assembly was 90% and obtained with 30 watts of laser power (Gaussian power distribution).
• FIGS. 15 and 16 show pictures of a portion of sealed devices made with two different low T g frits, C4 and C3, respectively. Both frits have T g values of about 300°C and both contain 20% zirconium phosphate filler for lowering CTE. Prior to laser-sealing, each frit was formulated into a paste, and then pre-sintered in air to the top temperature shown (360°C for 1 hour or 380°C for 1 hour), without any lower temperature burn-out hold used. Note that percent seal width, after laser-sealing, was excellent for the two samples, comparable to or better than the seal with CI, and ranging from 91% to 94%, both at 30 watts laser-power (Gaussian power distribution).
• sealing of the low T g frits was accomplished not only at lower temperature than the control frit, but without the need for a nitrogen atmosphere or burn-out temperature hold.
• the ability to sinter the frits in air at low temperature makes the sealing process less complicated, quicker and less costly to perform.
• control frit CI (which has exhibited no aqueous durability issues in numerous environmental and durability tests) has a durability index of 5.00, while a durability index equal to or less than about 3.40 is desirable for low T g frits.
• FIG. 17 Shown in FIG. 17 is an analysis for vanadium content (the most readily- leached species in both frits) for both the control frit (V 2 O 5 content equal to 47.5 mole %), and low T g frit composition C3 (V 2 O 5 content equal to 50.0 mole %) following two different aqueous durability tests on sintered frit samples:
• Both frits contained 20 weight % of CTE modifying filler ( ⁇ -quartz for CI, zirconium phosphate for the low T g frit C3), and were pre- sintered on their optimum pre-sintering schedule (for the control frit: 325°C for 1 hour in air and 400°C for 1 hour in N 2 .
• Specific results of the testing are provided in Table 17 giving mean delamination failure load (Newtons), as well as the standard deviation and B10, where B10 represents the estimated 10% point of failure loads.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Ceramic Engineering (AREA)
• Glass Compositions (AREA)

Priority Applications (3)

Applications Claiming Priority (6)

Publications (1)

Family

ID=55300818

Family Applications (1)

Country Status (5)

Cited By (5)

Families Citing this family (8)

Citations (5)

Family Cites Families (2)

• 2016
  • 2016-01-28 TW TW105102682A patent/TWI677483B/zh not_active IP Right Cessation
  • 2016-01-28 CN CN201680018714.2A patent/CN107406305A/zh active Pending
  • 2016-01-28 JP JP2017539566A patent/JP2018507836A/ja active Pending
  • 2016-01-28 WO PCT/US2016/015246 patent/WO2016123273A1/en active Application Filing
  • 2016-01-28 KR KR1020177023532A patent/KR20170107062A/ko unknown

Patent Citations (5)

Also Published As

Similar Documents

Legal Events