KR101260516B1 - 열안정성 폴리카보네이트 조성물 - Google Patents

열안정성 폴리카보네이트 조성물 Download PDF

Info

Publication number
KR101260516B1
KR101260516B1 KR1020050054391A KR20050054391A KR101260516B1 KR 101260516 B1 KR101260516 B1 KR 101260516B1 KR 1020050054391 A KR1020050054391 A KR 1020050054391A KR 20050054391 A KR20050054391 A KR 20050054391A KR 101260516 B1 KR101260516 B1 KR 101260516B1
Authority
KR
South Korea
Prior art keywords
polycarbonate
hydroxyphenyl
bis
carbonate
formula
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.)
Expired - Fee Related
Application number
KR1020050054391A
Other languages
English (en)
Korean (ko)
Other versions
KR20060049663A (ko
Inventor
헬무트-베르너 호이어
멜라니 뫼트라트
Original Assignee
바이엘 머티리얼사이언스 아게
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
Priority claimed from DE200410030664 external-priority patent/DE102004030664A1/de
Priority claimed from DE200410057349 external-priority patent/DE102004057349A1/de
Application filed by 바이엘 머티리얼사이언스 아게 filed Critical 바이엘 머티리얼사이언스 아게
Publication of KR20060049663A publication Critical patent/KR20060049663A/ko
Application granted granted Critical
Publication of KR101260516B1 publication Critical patent/KR101260516B1/ko
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/36Sulfur-, selenium-, or tellurium-containing compounds
    • C08K5/37Thiols
    • C08K5/375Thiols containing six-membered aromatic rings
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/36Sulfur-, selenium-, or tellurium-containing compounds
    • C08K5/41Compounds containing sulfur bound to oxygen
    • C08K5/42Sulfonic acids; Derivatives thereof
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/36Sulfur-, selenium-, or tellurium-containing compounds
    • C08K5/41Compounds containing sulfur bound to oxygen
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/36Sulfur-, selenium-, or tellurium-containing compounds
    • C08K5/45Heterocyclic compounds having sulfur in the ring
    • C08K5/46Heterocyclic compounds having sulfur in the ring with oxygen or nitrogen in the ring
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L69/00Compositions of polycarbonates; Compositions of derivatives of polycarbonates

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Polyesters Or Polycarbonates (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
KR1020050054391A 2004-06-24 2005-06-23 열안정성 폴리카보네이트 조성물 Expired - Fee Related KR101260516B1 (ko)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE102004030664.8 2004-06-24
DE200410030664 DE102004030664A1 (de) 2004-06-24 2004-06-24 Benzol- und Toluolsulfonsäureester als Additive in Polycarbonat
DE102004057349.2 2004-11-27
DE200410057349 DE102004057349A1 (de) 2004-11-27 2004-11-27 Benzol- und Toluolsulfonsäureester als Additive in Polycarbonat

Publications (2)

Publication Number Publication Date
KR20060049663A KR20060049663A (ko) 2006-05-19
KR101260516B1 true KR101260516B1 (ko) 2013-05-03

Family

ID=34937489

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020050054391A Expired - Fee Related KR101260516B1 (ko) 2004-06-24 2005-06-23 열안정성 폴리카보네이트 조성물

Country Status (9)

Country Link
US (1) US20050288407A1 (enExample)
EP (1) EP1609818B1 (enExample)
JP (1) JP5242001B2 (enExample)
KR (1) KR101260516B1 (enExample)
AT (1) ATE460458T1 (enExample)
DE (1) DE502005009170D1 (enExample)
ES (1) ES2340500T3 (enExample)
SG (2) SG118410A1 (enExample)
TW (1) TWI403555B (enExample)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10017608B2 (en) 2015-09-01 2018-07-10 Lg Chem, Ltd. Copolycarbonate and method for preparing the same

Families Citing this family (44)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6974260B2 (en) * 2003-07-30 2005-12-13 Emcore Corporation Flexible substrate for routing fibers in an optical transceiver
US20080014446A1 (en) * 2004-10-07 2008-01-17 General Electric Company Window shade and a multi-layered article, and methods of making the same
US7511092B2 (en) * 2005-10-07 2009-03-31 Sabic Innovative Plastics Ip B.V. Stabilized thermoplastic composition, method of making, and articles formed therefrom
US7557153B2 (en) 2005-10-31 2009-07-07 Sabic Innovative Plastics Ip Bv Ionizing radiation stable thermoplastic composition, method of making, and articles formed therefrom
US7812078B2 (en) * 2005-10-31 2010-10-12 Sabic Innovative Plastics Ip B.V. Ionizing radiation stable thermoplastic composition, method of making, and articles formed therefrom
US7649039B2 (en) 2005-10-31 2010-01-19 Sabic Innovative Plastics Ip B.V. Ionizing radiation stable thermoplastic composition, method of making, and articles formed therefrom
US7528212B2 (en) 2005-11-18 2009-05-05 Sabic Innovative Plastics Ip B.V. Ionizing radiation stable thermoplastic composition, method of making, and articles formed therefrom
JP5347244B2 (ja) * 2006-08-04 2013-11-20 三菱化学株式会社 ハロゲン含有ポリカーボネート樹脂の製造方法
US7652083B2 (en) * 2006-09-29 2010-01-26 Sabic Innovative Plastics Ip B.V. Thermoplastic compostions, methods of making, and articles formed therefrom
DE102007022130B4 (de) 2007-05-11 2015-02-19 Bayer Intellectual Property Gmbh Verfahren zur Herstellung von Polycarbonat nach dem Schmelzeumesterungsverfahren
DE102007052968A1 (de) * 2007-11-07 2009-05-14 Bayer Materialscience Ag Verfahren zur Herstellung von Polycarbonat nach dem Schmelzeumesterungsverfahren
DE102008008842A1 (de) 2008-02-13 2009-08-27 Bayer Materialscience Ag Alkylphenol zur Einstellung des Molekulargewichtes und Polycarbonatzusammensetzungen mit verbesserten Eigenschaften
KR100898899B1 (ko) * 2008-02-29 2009-05-26 제일모직주식회사 열안정성 및 내가수분해성이 향상된 폴리카보네이트의 제조방법 및 이로부터 제조된 폴리카보네이트 수지
DE102008011903A1 (de) 2008-02-29 2009-09-03 Bayer Materialscience Ag Polycarbonate mit cyclischen Oligomeren und verbessertem Fließverhalten
DE102008019503A1 (de) 2008-04-18 2009-10-22 Bayer Materialscience Ag Polycarbonate mit Umlagerungsstrukturen, cyclischen und linearen Oligomeren sowie verbessertem Fließverhalten
DE102008023800A1 (de) 2008-05-15 2009-11-19 Bayer Materialscience Ag Alkylphenol zur Einstellung des Molekulargewichtes und Copolycarbonat mit verbesserten Eigenschaften
US8771829B2 (en) * 2008-09-25 2014-07-08 Sabic Innovative Plastics Ip B.V. Flame retardant thermoplastic polymer composition, method of manufacture, and articles formed therefrom
US8445568B2 (en) * 2008-09-25 2013-05-21 Sabic Innovative Plastics Ip B.V. Flame retardant thermoplastic composition and articles formed therefrom
US20100280159A1 (en) * 2008-09-25 2010-11-04 Christianus Johannes Jacobus Maas Flame retardant thermoplastic composition and articles formed therefrom
DE102009043513A1 (de) 2009-09-30 2011-03-31 Bayer Materialscience Ag Polycarbonatzusammensetzungen mit verbesserten optischen Eigenschaften
DE102009043510A1 (de) 2009-09-30 2011-03-31 Bayer Materialscience Ag Polycarbonatzusammensetzungen mit verbesserter Schmelzstabilität
KR101282709B1 (ko) * 2009-12-21 2013-07-05 제일모직주식회사 열안정성이 향상된 난연 폴리카보네이트계 수지조성물 및 그 제조방법
EP2578390A1 (de) 2011-10-07 2013-04-10 Bayer MaterialScience AG Prozess zur Herstellung metallisierter Mehrschichtkörper aus speziellen Polycarbonaten
EP2578635A1 (de) 2011-10-07 2013-04-10 Bayer MaterialScience AG Polycarbonatzusammensetzungen mit guter Metallisierbarkeit
US9823393B2 (en) 2011-11-30 2017-11-21 Covestro Deutschland Ag Metallized multilayer structure made of specific polycarbonates with low coefficient of thermal expansion
JP6701076B2 (ja) 2013-10-02 2020-05-27 コベストロ、ドイチュラント、アクチエンゲゼルシャフトCovestro Deutschland Ag ストラクチュラルフォーム成形による成形体の製造方法、発泡熱可塑性材料成型部品およびその使用
JP6828954B2 (ja) 2013-11-11 2021-02-10 出光興産株式会社 ポリカーボネート樹脂成形材料
JP7106809B2 (ja) 2013-11-11 2022-07-27 出光興産株式会社 芳香族ポリカーボネート樹脂成形体
WO2015113916A1 (en) 2014-01-30 2015-08-06 Bayer Materialscience Ag Polysiloxane-polycarbonate block cocondensates with improved rheological properties
US10189941B2 (en) 2014-12-04 2019-01-29 Covestro Deutschland Ag Polycarbonate compositions containing polyethylene wax
CN109196048B (zh) 2016-05-27 2021-09-21 高新特殊工程塑料全球技术有限公司 具有增强的光学性质的共聚碳酸酯组合物、由其形成的制品和制造方法
CN109153848B (zh) 2016-05-27 2021-01-08 沙特基础工业全球技术有限公司 具有增强的光学性能的高热共聚碳酸酯组合物、由其形成的制品、和制造方法
US10787568B2 (en) 2016-07-25 2020-09-29 Sabic Global Technologies B.V. Polycarbonate compositions having enhanced optical properties, articles formed therefrom, and methods of manufacture
KR102644544B1 (ko) 2016-09-21 2024-03-11 넥스트큐어 인코포레이티드 Siglec-15를 위한 항체 및 이의 사용 방법
US10053533B1 (en) 2017-04-13 2018-08-21 Presidium Usa, Inc. Oligomeric polyol compositions
WO2019058332A1 (en) * 2017-09-22 2019-03-28 Sabic Global Technologies B.V. COMPOSITION AND METHOD FOR BED POWDER BED FUSION
CN111448255B (zh) 2017-12-19 2022-10-18 科思创德国股份有限公司 具有良好稳定性的热塑性组合物
EP3581605A1 (de) 2018-06-14 2019-12-18 Covestro Deutschland AG Schmelzeumesterungsverfahren zur gleichzeitigen herstellung mindestens zweier verschiedenartiger polycarbonate in einer produktionsanlage
EP3611156A1 (de) 2018-08-17 2020-02-19 Covestro Deutschland AG Verfahren zur herstellung eines cycloaliphatischen diesters
EP3663277A1 (de) 2018-12-07 2020-06-10 Covestro Deutschland AG Verfahren zur herstellung einer hydroxyverbindung durch decarboxylierung
KR20210100619A (ko) 2018-12-07 2021-08-17 코베스트로 인텔렉쳐 프로퍼티 게엠베하 운트 콤파니 카게 브뢴스테드 염기의 존재 하에 탈카르복실화에 의해 히드록시 화합물을 제조하는 방법
WO2021089534A1 (de) 2019-11-07 2021-05-14 Covestro Intellectual Property Gmbh & Co. Kg Verfahren zur herstellung von polyestercarbonaten
CN114829451B (zh) 2019-12-16 2024-08-16 科思创德国股份有限公司 制备聚酯碳酸酯的方法
EP3838979B1 (de) 2019-12-17 2024-06-26 Covestro Deutschland AG Schmelzepolycarbonat mit verbesserten optischen eigenschaften

Family Cites Families (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4092288A (en) * 1974-11-04 1978-05-30 General Electric Company Stabilized polycarbonate resin
JPS5364262A (en) * 1976-11-19 1978-06-08 Mitsubishi Gas Chem Co Inc Stabilization of polycarbonate resin
US4104264A (en) * 1977-05-05 1978-08-01 Air Products & Chemicals, Inc. End capped polyalkylene carbonates having improved thermal stablity
IT1213173B (it) * 1984-06-04 1989-12-14 Chiesi Farma Spa Composti ad attivita'antibatterica, procedimento per laloro preparazione e relative composizioni farmaceutiche.
JPH0692529B2 (ja) * 1989-12-28 1994-11-16 日本ジーイープラスチックス株式会社 芳香族系ポリカーボネートの製造方法
JP2924985B2 (ja) * 1991-06-28 1999-07-26 日本ジーイープラスチックス株式会社 ポリカーボネートの製造方法
DE4132629A1 (de) * 1991-10-01 1993-04-08 Bayer Ag Verwendung von kern-aromatischen sulfonsaeureestern zur stabilisierung von thermoplastischen polycarbonaten gegen einwirkung von gammastrahlen
ES2185644T3 (es) * 1993-08-26 2003-05-01 Teijin Ltd Procedimiento de produccion de policarbonato estabilizado.
JP3434613B2 (ja) * 1995-04-04 2003-08-11 新日鐵化学株式会社 感熱記録材料
JPH08311324A (ja) * 1995-05-22 1996-11-26 Mitsubishi Eng Plast Kk ポリカーボネート樹脂組成物
DE69628613T2 (de) * 1995-07-12 2004-04-29 Mitsubishi Engineering-Plastics Corp. Polycarbonatharzzusammensetzung
JPH0931315A (ja) * 1995-07-19 1997-02-04 Mitsubishi Eng Plast Kk ポリカーボネート樹脂組成物
US5644017A (en) * 1995-08-25 1997-07-01 The Dow Chemical Company Polycarbonate terminated by an ionic sulfonated aromatic moiety and preparation thereof
US5674968A (en) * 1995-08-25 1997-10-07 The Dow Chemical Company Aromatic sulfonated diester monomer, process to synthesize, polymer derived therefrom and method to prepare said polymer
JPH09255861A (ja) * 1996-03-27 1997-09-30 Mitsubishi Eng Plast Kk ポリカーボネート樹脂組成物
US5948838A (en) * 1996-03-06 1999-09-07 Mitsubishi Engineering-Plastics Corp. Polycarbonate resin composition
JPH09310010A (ja) * 1996-05-23 1997-12-02 Mitsubishi Eng Plast Kk ポリカーボネート樹脂組成物
US6727294B2 (en) * 1998-07-28 2004-04-27 Mitsubishi Engineering-Plastics Corporation Thermoplastic resin composition containing a naphthalene dicarboxylic acid moiety and an aliphatic diol moiety
JP4056645B2 (ja) * 1998-12-08 2008-03-05 Sabicイノベーティブプラスチックスジャパン合同会社 光学用ポリカーボネート樹脂組成物
JP2001279085A (ja) * 2000-01-25 2001-10-10 Mitsubishi Engineering Plastics Corp 熱可塑性樹脂組成物、熱可塑性樹脂成型品および医療用部品
DE10357161A1 (de) * 2003-12-06 2005-06-30 Bayer Materialscience Ag Verfahren zur Herstellung von Polycarbonaten mit geringem Gehalt an flüchtigen Verbindungen nach dem Umesterungsverfahren

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10017608B2 (en) 2015-09-01 2018-07-10 Lg Chem, Ltd. Copolycarbonate and method for preparing the same

Also Published As

Publication number Publication date
SG153861A1 (en) 2009-07-29
DE502005009170D1 (de) 2010-04-22
US20050288407A1 (en) 2005-12-29
KR20060049663A (ko) 2006-05-19
JP2006009022A (ja) 2006-01-12
EP1609818A2 (de) 2005-12-28
ATE460458T1 (de) 2010-03-15
ES2340500T3 (es) 2010-06-04
SG118410A1 (en) 2006-01-27
EP1609818A3 (de) 2006-12-27
EP1609818B1 (de) 2010-03-10
JP5242001B2 (ja) 2013-07-24
TW200615330A (en) 2006-05-16
TWI403555B (zh) 2013-08-01

Similar Documents

Publication Publication Date Title
KR101260516B1 (ko) 열안정성 폴리카보네이트 조성물
ES2394418T3 (es) Policarbonatos con estructuras de transposición, oligómeros cíclicos y lineales así como comportamiento de flujo mejorado
US7814626B2 (en) Process for the preparation of polycarbonate by the melt transesterification process
TWI492960B (zh) 烷基酚-封端的共聚碳酸酯,其製備方法,包含其之模製組成物,及由其製得之物件
US6887970B2 (en) Method for producing polycarbonates
KR20130024905A (ko) 열 노화가 개선된 용융 폴리카르보네이트
KR20130051936A (ko) 개선된 광학적 및 열적 특성을 갖는 폴리카르보네이트 조성물
KR101608984B1 (ko) 폴리카르보네이트 제조를 위한 상 계면 방법
JP5241552B2 (ja) ポリカーボネートおよびジアリールカーボネートの製造方法
JP4694502B2 (ja) 低含量の揮発性化合物を有するポリカーボネートのトランスエステル化法による製造方法
KR20100122080A (ko) 분자량을 조정하기 위한 알킬페놀,및 개선된 특성을 갖는 폴리카르보네이트 조성물
ES2340394T3 (es) Inhibicion de impurezas cataliticamente activas en policarbonato segun el procedimiento de transesterificacion en masa fundida.
KR102307698B1 (ko) 상 계면 방법에 따른 폴리카르보네이트의 제조 방법
US6797837B2 (en) Process for the preparation of stabilized polycarbonate
CN1712450B (zh) 热稳定的聚碳酸酯组合物
CN100549062C (zh) 抑制熔体酯交换方法制备的聚碳酸酯中的催化活性杂质
KR102637370B1 (ko) 염화탄화수소를 기재로 하는 유기 용매를 사용하여 폴리카르보네이트를 제조하는 방법
US6716933B2 (en) Working up of polymer synthesis solutions
DE102004057349A1 (de) Benzol- und Toluolsulfonsäureester als Additive in Polycarbonat
MXPA02004395A (es) Substratos de policarbonato.
HK1135423A (en) Process for the preparation of polycarbonates and diaryl carbonate
KR20110073322A (ko) 폴리카르보네이트를 제조하는 방법 및 장치

Legal Events

Date Code Title Description
PA0109 Patent application

St.27 status event code: A-0-1-A10-A12-nap-PA0109

PG1501 Laying open of application

St.27 status event code: A-1-1-Q10-Q12-nap-PG1501

A201 Request for examination
P11-X000 Amendment of application requested

St.27 status event code: A-2-2-P10-P11-nap-X000

P13-X000 Application amended

St.27 status event code: A-2-2-P10-P13-nap-X000

PA0201 Request for examination

St.27 status event code: A-1-2-D10-D11-exm-PA0201

R18-X000 Changes to party contact information recorded

St.27 status event code: A-3-3-R10-R18-oth-X000

PE0902 Notice of grounds for rejection

St.27 status event code: A-1-2-D10-D21-exm-PE0902

R18-X000 Changes to party contact information recorded

St.27 status event code: A-3-3-R10-R18-oth-X000

T11-X000 Administrative time limit extension requested

St.27 status event code: U-3-3-T10-T11-oth-X000

T11-X000 Administrative time limit extension requested

St.27 status event code: U-3-3-T10-T11-oth-X000

T11-X000 Administrative time limit extension requested

St.27 status event code: U-3-3-T10-T11-oth-X000

T11-X000 Administrative time limit extension requested

St.27 status event code: U-3-3-T10-T11-oth-X000

P11-X000 Amendment of application requested

St.27 status event code: A-2-2-P10-P11-nap-X000

P13-X000 Application amended

St.27 status event code: A-2-2-P10-P13-nap-X000

PE0902 Notice of grounds for rejection

St.27 status event code: A-1-2-D10-D21-exm-PE0902

P11-X000 Amendment of application requested

St.27 status event code: A-2-2-P10-P11-nap-X000

P13-X000 Application amended

St.27 status event code: A-2-2-P10-P13-nap-X000

E701 Decision to grant or registration of patent right
PE0701 Decision of registration

St.27 status event code: A-1-2-D10-D22-exm-PE0701

GRNT Written decision to grant
PR0701 Registration of establishment

St.27 status event code: A-2-4-F10-F11-exm-PR0701

PR1002 Payment of registration fee

St.27 status event code: A-2-2-U10-U11-oth-PR1002

Fee payment year number: 1

PG1601 Publication of registration

St.27 status event code: A-4-4-Q10-Q13-nap-PG1601

FPAY Annual fee payment

Payment date: 20160329

Year of fee payment: 4

PR1001 Payment of annual fee

St.27 status event code: A-4-4-U10-U11-oth-PR1001

Fee payment year number: 4

R18-X000 Changes to party contact information recorded

St.27 status event code: A-5-5-R10-R18-oth-X000

FPAY Annual fee payment

Payment date: 20170330

Year of fee payment: 5

PR1001 Payment of annual fee

St.27 status event code: A-4-4-U10-U11-oth-PR1001

Fee payment year number: 5

PR1001 Payment of annual fee

St.27 status event code: A-4-4-U10-U11-oth-PR1001

Fee payment year number: 6

FPAY Annual fee payment

Payment date: 20190328

Year of fee payment: 7

PR1001 Payment of annual fee

St.27 status event code: A-4-4-U10-U11-oth-PR1001

Fee payment year number: 7

PR1001 Payment of annual fee

St.27 status event code: A-4-4-U10-U11-oth-PR1001

Fee payment year number: 8

PC1903 Unpaid annual fee

St.27 status event code: A-4-4-U10-U13-oth-PC1903

Not in force date: 20210427

Payment event data comment text: Termination Category : DEFAULT_OF_REGISTRATION_FEE

PC1903 Unpaid annual fee

St.27 status event code: N-4-6-H10-H13-oth-PC1903

Ip right cessation event data comment text: Termination Category : DEFAULT_OF_REGISTRATION_FEE

Not in force date: 20210427