CN112456794A - Alkali-free glass for liquid crystal display and preparation method thereof - Google Patents

Alkali-free glass for liquid crystal display and preparation method thereof Download PDF

Info

Publication number
CN112456794A
CN112456794A CN202011473357.3A CN202011473357A CN112456794A CN 112456794 A CN112456794 A CN 112456794A CN 202011473357 A CN202011473357 A CN 202011473357A CN 112456794 A CN112456794 A CN 112456794A
Authority
CN
China
Prior art keywords
glass
alkali
liquid crystal
crystal display
hours
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
CN202011473357.3A
Other languages
Chinese (zh)
Inventor
彭寿
马立云
仲召进
曹欣
倪嘉
赵凤阳
崔介东
单传丽
王萍萍
高强
王巍巍
韩娜
石丽芬
杨勇
柯震坤
李金威
李常青
周刚
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CNBM Bengbu Design and Research Institute for Glass Industry Co Ltd
Original Assignee
CNBM Bengbu Design and Research Institute for Glass Industry Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CNBM Bengbu Design and Research Institute for Glass Industry Co Ltd filed Critical CNBM Bengbu Design and Research Institute for Glass Industry Co Ltd
Priority to CN202011473357.3A priority Critical patent/CN112456794A/en
Publication of CN112456794A publication Critical patent/CN112456794A/en
Withdrawn legal-status Critical Current

Links

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
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/095—Glass compositions containing silica with 40% to 90% silica, by weight containing rare earths
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/02—Other methods of shaping glass by casting molten glass, e.g. injection moulding
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/235—Heating the glass

Landscapes

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

Abstract

The invention relates to alkali-free glass for liquid crystal display and a preparation method thereof, which are characterized in that: weighing the raw materials, SiO in percentage by mass254~66%、Al2O314~18%、GeO20.5~3%、CaO3~6%、B2O36~11%、MgO3~6%、SrO5~11%、SnO0.1~0.3%，Y2O30~0.5%，La2O30~0.5%，Ce2O30~0.5%，Yb2O30 to 0.5%, wherein Y2O3+La2O3+Ce2O3+Yb2O30.4-1.5%; melting according to the following melting system: heating the mixture from room temperature to 1100 ℃ for 2-3 hours; the temperature is increased from 1100 ℃ to 1640 ℃, the time of use is 3-4 hours, and the glass liquid is stirred discontinuously in the period, so that bubbles can be discharged betterDischarging; and preserving the heat for 2-3 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate. Has the advantages that: the melting temperature is low, the viscosity is low, and bubbles are easy to remove; the prepared alkali-free glass has the strain point higher than 660 ℃, the annealing point higher than 705 ℃, and the density less than 2.6g/cm3The bending strength is more than 92MPa, and various basic characteristics required by the substrate glass for liquid crystal display are achieved.

Description

Alkali-free glass for liquid crystal display and preparation method thereof
Technical Field
The invention belongs to the field of glass preparation, relates to alkali-free glass, and particularly relates to alkali-free glass for liquid crystal display and a preparation method thereof.
Background
Glass substrates for displays such as liquid crystal displays are required to be substantially free of alkali metals (alkali-free glasses), but glass melting processes are much more difficult than conventional soda-lime-silicate glasses because the glass raw materials are substantially free of alkali metal compounds and have a high alumina content, the glass melting temperature is high, the viscosity is high, and bubbles are difficult to remove. When a certain amount of microbubbles remain in the alkali-free glass substrate and the homogeneity is poor during the glass melting process, the microbubbles affect the appearance, transmittance, mechanical strength, hardness, and the like of the glass product, and thus the glass substrate cannot meet the requirements of a display such as a liquid crystal display.
In general, in order to achieve various basic characteristics required for a substrate glass for liquid crystal display, for example, a strain point of more than 660 ℃, an annealing point of more than 705 ℃, and a density of less than 2.6g/cm3Etc.; on the basis of meeting the requirements, the melting temperature of the glass, the viscosity of the glass liquid and the performances of improving the bending strength, the elastic modulus and the like of the glass become the biggest difficulties.
Disclosure of Invention
The invention aims to solve the technical problems and provide alkali-free glass for liquid crystal display and a preparation method thereof. The invention realizes the purposes of reducing the glass melting temperature and the viscosity of glass liquid and improving the bending strength, the elastic modulus, the strain point and other properties of the glass by controlling the formula, and prepares the alkali-free glass for the liquid crystal display, which has less bubbles and good homogeneity.
The technical scheme adopted by the invention for solving the technical problems is as follows:
an alkali-free glass for liquid crystal display, characterized in that: the material is prepared from the following raw materials in percentage by mass: SiO 2254~66%、Al2O314~18%、GeO20.5~3%、CaO3~6%、B2O36~11%、MgO3~6%、SrO5~11%、SnO0.1~0.3%，Y2O30~0.5%，La2O30~0.5%，Ce2O30~0.5%，Yb2O30 to 0.5%, wherein Y2O3+La2O3+Ce2O3+Yb2O30.4~1.5%。
Further, an alkali-free glass for liquid crystal display, characterized in that: the material is prepared from the following raw materials in percentage by mass: SiO 2257~63%、Al2O315~18%、GeO20.5~2%、CaO3~6%、B2O37~10%、MgO3~5%、SrO6~10%、SnO0.1~0.3%，Y2O30~0.5%，La2O30~0.5%，Ce2O30~0.5%，Yb2O30 to 0.5%, wherein Y2O3+La2O3+Ce2O3+Yb2O30.4~1.0%。
Further, an alkali-free glass for liquid crystal display, characterized in that: the material is prepared from the following raw materials in percentage by mass: SiO 2259~61%、Al2O316~17%、GeO21~2%、CaO3~6%、B2O38~9%、MgO3~4%、SrO7~9%、SnO0.1~0.3%，Y2O30~0.5%，La2O30~0.5%，Ce2O30~0.5%，Yb2O30 to 0.5%, wherein Y2O3+La2O3+Ce2O3+Yb2O30.6~1.0%。
A preparation method of alkali-free glass for liquid crystal display is characterized by comprising the following steps: weighing the raw materials according to the mass percent, and melting the glass according to the following melting system: heating the mixture from room temperature to 1100 ℃ for 2-3 hours; heating the glass melt to 1640 ℃ from 1100 ℃, and stirring the glass melt intermittently for 3-4 hours during use, so that bubbles can be discharged better; and preserving the heat for 2-3 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
GeO2Is beneficial to reducing the melting temperature of the glass because of GeO2Melting point ratio of (A) SiO2Very small, GeO2Viscous activation energy of the melt is also higher than that of SiO2Small, thereby causing high temperature of molten glassThe viscosity is reduced, which is beneficial to discharging bubbles and is easy to control the forming of the glass; GeO2Also network formers, GeO2Gradual substitution of SiO2Then due to GeO2Glass network structure of (2) SiO2When GeO2When the substitution amount is increased, the distance between atoms is increased, so that the dipole moment of the atoms is changed, and the Raman intensity is influenced; when GeO2When the amount increases, 470 cm-1And 1040 cm-1The Raman spectrum intensity of the light source is firstly reduced and then increased, which is similar to GeO2The introduced amount of (2) is related to;
B2O3good fluxing effect can be brought, the thermal stability and the chemical stability of the glass are improved, but the strain point of the glass is obviously reduced due to excessive addition;
the rare earth oxide has obvious effects on improving the bending strength, the elastic modulus, the strain point and other properties of the glass, promotes the brittleness of the glass to be reduced, greatly increases the fracture toughness, and can reduce the high-temperature viscosity of the glass;
after the network outer body of alkaline earth metal and the like is introduced into the glass composition, the excessive oxygen atoms break the bridge oxygen bonds in the glass structure to generate non-bridge oxygen, and the presence of the non-bridge oxygen reduces the bending strength of the glass.
The invention has the beneficial effects that:
(1) the alkali-free glass prepared by the glass formula has lower melting temperature (1650-2Pa x s) is 1420-1440 deg.C), and the air bubbles are easy to remove (the melting temperature is low, the viscosity is low); in the glass melting process of the traditional alkali-free glass formula, when a certain amount of micro bubbles remain on a glass substrate due to high melting temperature, high viscosity and the like and the homogeneity is poor, the appearance, the transmittance, the mechanical strength, the hardness and the like of a glass product are influenced;
(2) the alkali-free glass prepared by the glass formula has stable performance, the strain point is higher than 660 ℃, the annealing point is higher than 705 ℃, and the density is 2.5-2.6g/cm3The bending strength reaches 90-100MPa, and the substrate for liquid crystal display is obtainedVarious basic properties are required of glass.
Detailed Description
A preparation method of alkali-free glass for liquid crystal display comprises the following specific implementation steps:
example 1
(1) Weighing the following raw materials in percentage by mass: 58.5% SiO216.04% of Al2O31% of GeO24.25 percent of CaO, 8.15 percent of B2O33.26% of MgO, 7.40% of SrO and 0.4% of Y2O30.4% of La2O30.3% of Ce2O30.3% of Yb2O3（Y2O3+La2O3+Ce2O3+Yb2O31.4%), 0.17% SnO;
(2) melting the raw materials according to the following melting system: heating from room temperature to 1100 deg.c for 2 hr; heating the glass melt from 1100 ℃ to 1640 ℃, stirring the glass melt intermittently for 3 hours during the heating, discharging bubbles better, and keeping the temperature for 2 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
Example 2
(1) Weighing the following raw materials in percentage by mass: 58.6% SiO216.14% of Al2O31% of GeO24.25 percent of CaO, 8.15 percent of B2O3MgO 3.46%, SrO 7.50%, Y0.3%2O30.2% of La2O30.3% of Ce2O30.1% of Yb2O3（Y2O3+La2O3+Ce2O3+Yb2O30.9%), 0.17% SnO;
(2) melting the raw materials according to the following melting system: heating from room temperature to 1100 deg.c for 2 hr; heating the glass melt from 1100 ℃ to 1640 ℃, stirring the glass melt intermittently for 3 hours during the heating, discharging bubbles better, and keeping the temperature for 2 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
Example 3
(1) Weighing the following raw materials in percentage by mass: 58.7% SiO216.24% of Al2O31% of GeO24.25 percent of CaO, 8.15 percent of B2O33.46 percent of MgO, 7.60 percent of SrO and 0.2 percent of Y2O30.1% of La2O30.2% of Ce2O30.1% of Yb2O3（Y2O3+La2O3+Ce2O3+Yb2O30.6%), 0.17% SnO;
(2) melting the raw materials according to the following melting system: heating from room temperature to 1100 deg.c for 2 hr; heating the glass melt from 1100 ℃ to 1640 ℃, stirring the glass melt intermittently for 3 hours during the heating, discharging bubbles better, and keeping the temperature for 2 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
Example 4
(1) Weighing the following raw materials in percentage by mass: 59.2% SiO216.24% of Al2O30.5% of GeO24.25 percent of CaO, 8.15 percent of B2O33.46 percent of MgO, 7.60 percent of SrO and 0.2 percent of Y2O30.1% of La2O30.2% of Ce2O30.1% of Yb2O3（Y2O3+La2O3+Ce2O3+Yb2O30.6%), 0.17% SnO;
(2) melting the raw materials according to the following melting system: heating from room temperature to 1100 deg.c for 2 hr; heating the glass melt from 1100 ℃ to 1640 ℃, stirring the glass melt intermittently for 3 hours during the heating, discharging bubbles better, and keeping the temperature for 2 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
Example 5
(1) Weighing the following raw materials in percentage by mass: 56.7% SiO216.24% of Al2O33% of GeO24.25 percent of CaO, 8.15 percent of B2O33.46 percent of MgO, 7.60 percent of SrO and 0.2 percent of Y2O30.1% of La2O30.2% of Ce2O30.1% of Yb2O3（Y2O3+La2O3+Ce2O3+Yb2O30.6%), 0.17% SnO;
(2) melting the raw materials according to the following melting system: heating from room temperature to 1100 deg.c for 2 hr; heating the glass melt from 1100 ℃ to 1640 ℃, stirring the glass melt intermittently for 3 hours during the heating, discharging bubbles better, and keeping the temperature for 2 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
Example 6
(1) Weighing the following raw materials in percentage by mass: 57.7% SiO216.24% of Al2O32% of GeO24.25 percent of CaO, 8.15 percent of B2O33.46 percent of MgO, 7.60 percent of SrO and 0.2 percent of Y2O30.1% of La2O30.2% of Ce2O30.1% of Yb2O3（Y2O3+La2O3+Ce2O3+Yb2O30.6%), 0.17% SnO;
(2) melting the raw materials according to the following melting system: heating from room temperature to 1100 deg.c for 2 hr; heating the glass melt from 1100 ℃ to 1640 ℃, stirring the glass melt intermittently for 3 hours during the heating, discharging bubbles better, and keeping the temperature for 2 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
Comparative example 1
(1) According to the following massWeighing the following raw materials in percentage: 59% SiO216.54% of Al2O31% of GeO24.25 percent of CaO, 8.15 percent of B2O33.46 percent of MgO, 7.60 percent of SrO and 0.17 percent of SnO;
(2) melting the raw materials according to the following melting system: heating from room temperature to 1100 deg.c for 2 hr; heating from 1100 deg.C to 1640 deg.C for 3 hr, and holding for 2 hr; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
The 6 examples described above employed the same melting system as in comparative example 1, except that the rare earth metal oxides were added in different amounts in examples 1 to 6, respectively; comparative example 1, however, does not contain any rare earth metal oxide and does not contain any stirring during the melting and refining processes, and the property profile is shown in table 1. Therefore, the formula and the preparation method provided by the invention can effectively reduce the melting temperature of the glass and the viscosity of the glass liquid, reduce micro bubbles, improve the bending strength, the elastic modulus, the strain point and other properties of the glass, and obtain high-quality alkali-free glass with good homogeneity.
Example 1 Example 2 Example 3 Example 4 Example 5 Practice ofExample 6 Comparative example 1
Melting temperature (. degree.C.) 1670 1664 1662 1664 1651 1657 1665
Molding viscosity (10)2Pa × s) corresponding temperature (. degree. C.) 1438 1433 1429 1431 1422 1427 1432
Strain point (. degree. C.) 675.2 672.8 671.9 672.1 667.2 669.5 674.2
Annealing Point (. degree.C.) 726.3 723.4 722.8 722.9 717.3 720.1 724.5
Softening Point (. degree. C.) 958.6 956.4 954.7 956.3 949.8 952.7 958.1
Density (g/cm)3） 2.549 2.552 2.553 2.543 2.561 2.557 2.548
Bending strength (MPa) 98.7 96.4 94.5 95.7 92.3 94.2 93.9
Modulus of elasticity (GPa) 73.2 72.6 72.3 72.4 71.6 71.9 71.8
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner; those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention.

Claims (4)

1. An alkali-free glass for liquid crystal display, characterized in that: the material is prepared from the following raw materials in percentage by mass: SiO 2254~66%、Al2O314~18%、GeO20.5~3%、CaO3~6%、B2O36~11%、MgO3~6%、SrO5~11%、SnO0.1~0.3%，Y2O30~0.5%，La2O30~0.5%，Ce2O30~0.5%，Yb2O30 to 0.5%, wherein Y2O3+La2O3+Ce2O3+Yb2O30.4~1.5%。
2. The alkali-free glass for liquid crystal display according to claim 1, wherein: the material is prepared from the following raw materials in percentage by mass: SiO 2257~63%、Al2O315~18%、GeO20.5~2%、CaO3~6%、B2O37~10%、MgO3~5%、SrO6~10%、SnO0.1~0.3%，Y2O30~0.5%，La2O30~0.5%，Ce2O30~0.5%，Yb2O30 to 0.5%, wherein Y2O3+La2O3+Ce2O3+Yb2O30.4~1.0%。
3. The alkali-free glass for liquid crystal display according to claim 1, wherein: the material is prepared from the following raw materials in percentage by mass: SiO 2259~61%、Al2O316~17%、GeO21~2%、CaO3~6%、B2O38~9%、MgO3~4%、SrO7~9%、SnO0.1~0.3%，Y2O30~0.5%，La2O30~0.5%，Ce2O30~0.5%，Yb2O30 to 0.5%, wherein Y2O3+La2O3+Ce2O3+Yb2O30.6~1.0%。
4. The method for producing an alkali-free glass for liquid crystal display according to any one of claims 1 to 3, comprising the steps of: weighing the raw materials according to the mass percent, and melting the glass according to the following melting system: heating the mixture from room temperature to 1100 ℃ for 2-3 hours; heating the glass melt to 1640 ℃ from 1100 ℃, and stirring the glass melt intermittently for 3-4 hours during use, so that bubbles can be discharged better; and preserving the heat for 2-3 hours; and then casting and forming by an iron plate casting forming method, and then annealing, cutting and polishing to obtain the glass substrate.
CN202011473357.3A 2020-12-15 2020-12-15 Alkali-free glass for liquid crystal display and preparation method thereof Withdrawn CN112456794A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202011473357.3A CN112456794A (en) 2020-12-15 2020-12-15 Alkali-free glass for liquid crystal display and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202011473357.3A CN112456794A (en) 2020-12-15 2020-12-15 Alkali-free glass for liquid crystal display and preparation method thereof

Publications (1)

Publication Number Publication Date
CN112456794A true CN112456794A (en) 2021-03-09

Family

ID=74803477

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202011473357.3A Withdrawn CN112456794A (en) 2020-12-15 2020-12-15 Alkali-free glass for liquid crystal display and preparation method thereof

Country Status (1)

Country Link
CN (1) CN112456794A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113248139A (en) * 2021-06-01 2021-08-13 中国建筑材料科学研究总院有限公司 Optical glass with high photoinduced refractive index change, optical fiber prepared from optical glass, and preparation method and application of optical fiber
CN113336437A (en) * 2021-06-01 2021-09-03 中国建筑材料科学研究总院有限公司 Optical glass with high photoinduced refractive index change, optical fiber prepared from optical glass, and preparation method and application of optical fiber

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113248139A (en) * 2021-06-01 2021-08-13 中国建筑材料科学研究总院有限公司 Optical glass with high photoinduced refractive index change, optical fiber prepared from optical glass, and preparation method and application of optical fiber
CN113336437A (en) * 2021-06-01 2021-09-03 中国建筑材料科学研究总院有限公司 Optical glass with high photoinduced refractive index change, optical fiber prepared from optical glass, and preparation method and application of optical fiber

Similar Documents

Publication Publication Date Title
CN110615610A (en) Lithium-zirconium aluminosilicate glass, tempered glass, preparation methods of lithium-zirconium aluminosilicate glass and tempered glass, and display device
CN112456794A (en) Alkali-free glass for liquid crystal display and preparation method thereof
CN104445932B (en) Pink aluminosilicate glass
CN110028240B (en) Aluminosilicate glass and preparation method thereof
CN110872175A (en) Glass ceramic and glass substrate with composite compressive stress prepared from same
CN110577365A (en) Nanocrystalline glass ceramic and preparation method thereof
CN102173592A (en) CaO-MgO-Al2O3-SiO2 microcrystalline glass and preparation method thereof
CN103626395B (en) A kind of preparation method of high-boron-silicon glass, high-boron-silicon glass and application thereof
CN107117821A (en) A kind of high strength micro-crystalline glass and preparation method thereof
CN110156334A (en) A kind of devitrified glass and preparation method thereof
CN112441741A (en) Ultrathin aluminosilicate glass and preparation method and application thereof
CN111302619A (en) Alkali-free aluminoborosilicate glass and preparation method thereof
CN108017281A (en) A kind of tempered glass and preparation method thereof
CN116102254A (en) OLED glass substrate composition and preparation method thereof
CN112408803B (en) Crystal toughened lithium-aluminum-silicate microcrystalline glass composite material and preparation method thereof
CN105916821B (en) Method for producing silicate glass, and silica raw material for silicate glass
CN111170632A (en) Alkali-free glass
CN108623154B (en) Surface-strengthened transparent glass
CN112521012B (en) Heat-resistant high-hardness high-light-transmittance glass ceramic and preparation method thereof
CN110803868A (en) Diopside reinforced mica-based machinable glass ceramic and preparation method thereof
CN111170634A (en) High-alumina phosphosilicate glass suitable for chemical strengthening and chemically toughened glass
CN101215089B (en) Formulation of peachblow glass and manufacturing technology thereof
CN109775963B (en) Decompression melting clarification method for alkali-free glass
CN104030567B (en) Si-Al-Ca microcrystalline glass in series prepared by Low-silica iron ore tailings and method
CN109650723A (en) A kind of the alkali-free high alumina Pyrex and preparation method of high rigidity

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
WW01 Invention patent application withdrawn after publication
WW01 Invention patent application withdrawn after publication

Application publication date: 20210309