AR019660A1 - Una composicion de combinacion de poliester fenilendi(oxiacetico, acido), de alta barrera - Google Patents
Una composicion de combinacion de poliester fenilendi(oxiacetico, acido), de alta barreraInfo
- Publication number
- AR019660A1 AR019660A1 ARP990102817A ARP990102817A AR019660A1 AR 019660 A1 AR019660 A1 AR 019660A1 AR P990102817 A ARP990102817 A AR P990102817A AR P990102817 A ARP990102817 A AR P990102817A AR 019660 A1 AR019660 A1 AR 019660A1
- Authority
- AR
- Argentina
- Prior art keywords
- poly
- weight
- acid
- polyester
- ethylene
- Prior art date
Links
- 229920000728 polyester Polymers 0.000 title abstract 5
- 239000000203 mixture Substances 0.000 title abstract 4
- 239000002253 acid Substances 0.000 title abstract 3
- 230000004888 barrier function Effects 0.000 title 1
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 abstract 6
- 229920001634 Copolyester Polymers 0.000 abstract 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 abstract 4
- UHPJWJRERDJHOJ-UHFFFAOYSA-N ethene;naphthalene-1-carboxylic acid Chemical compound C=C.C1=CC=C2C(C(=O)O)=CC=CC2=C1 UHPJWJRERDJHOJ-UHFFFAOYSA-N 0.000 abstract 4
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 abstract 4
- 229920000139 polyethylene terephthalate Polymers 0.000 abstract 4
- 239000005020 polyethylene terephthalate Substances 0.000 abstract 4
- 125000004432 carbon atom Chemical group C* 0.000 abstract 3
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 abstract 2
- YIMQCDZDWXUDCA-UHFFFAOYSA-N [4-(hydroxymethyl)cyclohexyl]methanol Chemical compound OCC1CCC(CO)CC1 YIMQCDZDWXUDCA-UHFFFAOYSA-N 0.000 abstract 2
- CDQSJQSWAWPGKG-UHFFFAOYSA-N butane-1,1-diol Chemical compound CCCC(O)O CDQSJQSWAWPGKG-UHFFFAOYSA-N 0.000 abstract 2
- 150000002148 esters Chemical class 0.000 abstract 2
- ACCCMOQWYVYDOT-UHFFFAOYSA-N hexane-1,1-diol Chemical compound CCCCCC(O)O ACCCMOQWYVYDOT-UHFFFAOYSA-N 0.000 abstract 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 abstract 2
- ULWHHBHJGPPBCO-UHFFFAOYSA-N propane-1,1-diol Chemical compound CCC(O)O ULWHHBHJGPPBCO-UHFFFAOYSA-N 0.000 abstract 2
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical group [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 abstract 1
- 230000002378 acidificating effect Effects 0.000 abstract 1
- 125000003545 alkoxy group Chemical group 0.000 abstract 1
- 125000000217 alkyl group Chemical group 0.000 abstract 1
- 239000007795 chemical reaction product Substances 0.000 abstract 1
- 229910052801 chlorine Inorganic materials 0.000 abstract 1
- 125000001309 chloro group Chemical group Cl* 0.000 abstract 1
- 150000002009 diols Chemical class 0.000 abstract 1
- 229910052731 fluorine Inorganic materials 0.000 abstract 1
- 125000001153 fluoro group Chemical group F* 0.000 abstract 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 abstract 1
- KYTZHLUVELPASH-UHFFFAOYSA-N naphthalene-1,2-dicarboxylic acid Chemical compound C1=CC=CC2=C(C(O)=O)C(C(=O)O)=CC=C21 KYTZHLUVELPASH-UHFFFAOYSA-N 0.000 abstract 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 abstract 1
- 229920001707 polybutylene terephthalate Polymers 0.000 abstract 1
- 229920001169 thermoplastic Polymers 0.000 abstract 1
- 239000004416 thermosoftening plastic Substances 0.000 abstract 1
- 125000003258 trimethylene group Chemical group [H]C([H])([*:2])C([H])([H])C([H])([H])[*:1] 0.000 abstract 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
- C08L67/025—Polyesters derived from dicarboxylic acids and dihydroxy compounds containing polyether sequences
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
- Y10T428/1397—Single layer [continuous layer]
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Laminated Bodies (AREA)
- Polyesters Or Polycarbonates (AREA)
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US8922198P | 1998-06-15 | 1998-06-15 | |
| US8922098P | 1998-06-15 | 1998-06-15 | |
| US8939198P | 1998-06-15 | 1998-06-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| AR019660A1 true AR019660A1 (es) | 2002-03-13 |
Family
ID=27376251
Family Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| ARP990102817A AR019660A1 (es) | 1998-06-15 | 1999-06-11 | Una composicion de combinacion de poliester fenilendi(oxiacetico, acido), de alta barrera |
| ARP990102818A AR018672A1 (es) | 1998-06-15 | 1999-06-11 | Una composicion de combinaciones de poliester /fenilendi(oxiacetico), acido copoliester, que tienen mejoradas propiedades de barrera de gases |
| ARP990102816A AR017749A1 (es) | 1998-06-15 | 1999-06-11 | Estructura de multiples estratos |
Family Applications After (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| ARP990102818A AR018672A1 (es) | 1998-06-15 | 1999-06-11 | Una composicion de combinaciones de poliester /fenilendi(oxiacetico), acido copoliester, que tienen mejoradas propiedades de barrera de gases |
| ARP990102816A AR017749A1 (es) | 1998-06-15 | 1999-06-11 | Estructura de multiples estratos |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US6254950B1 (enExample) |
| EP (3) | EP1095093A1 (enExample) |
| JP (3) | JP2002518537A (enExample) |
| CN (3) | CN1312837A (enExample) |
| AR (3) | AR019660A1 (enExample) |
| BR (3) | BR9911256A (enExample) |
| CA (3) | CA2334464A1 (enExample) |
| WO (3) | WO1999065967A1 (enExample) |
Families Citing this family (28)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1038905A3 (de) | 1999-03-26 | 2001-01-31 | Mitsubishi Polyester Film GmbH | Transparente, UV-stabilisierte Folie aus einem kristallisierbaren Thermoplast |
| AUPR005000A0 (en) * | 2000-09-12 | 2000-10-05 | Polymers Australia Pty Limited | Polyster resins with improved properties |
| US20040024102A1 (en) * | 2002-07-30 | 2004-02-05 | Hayes Richard Allen | Sulfonated aliphatic-aromatic polyetherester films, coatings, and laminates |
| US7482397B2 (en) * | 2003-01-13 | 2009-01-27 | Eastman Chemical Company | Polycarbonate compositions |
| US20040143041A1 (en) * | 2003-01-13 | 2004-07-22 | Pearson Jason Clay | Polyester compositions |
| US7297735B2 (en) * | 2003-03-05 | 2007-11-20 | Eastman Chemical Company | Polycarbonate compositions |
| US20040183053A1 (en) * | 2003-03-20 | 2004-09-23 | Pearson Jason Clay | Process for the preparation of a hindered amine light stabilizer salt |
| ATE390460T1 (de) * | 2003-03-05 | 2008-04-15 | Eastman Chem Co | Polymerblends |
| US20040192813A1 (en) * | 2003-03-20 | 2004-09-30 | Pearson Jason Clay | Polymer compositions containing an ultraviolet light absorbing compound |
| KR101158123B1 (ko) * | 2003-03-05 | 2012-06-19 | 이스트만 케미칼 컴파니 | 자외선 흡수 화합물을 함유하는 중합체 조성물 |
| US20040180994A1 (en) * | 2003-03-05 | 2004-09-16 | Pearson Jason Clay | Polyolefin compositions |
| US7338992B2 (en) * | 2003-03-05 | 2008-03-04 | Eastman Chemical Company | Polyolefin compositions |
| US20050277713A1 (en) * | 2003-03-05 | 2005-12-15 | Pearson Jason C | Polymer blends |
| JP2006118392A (ja) * | 2004-10-20 | 2006-05-11 | Nissan Motor Co Ltd | 多層樹脂配管及び多層樹脂容器 |
| US7396896B2 (en) * | 2004-12-21 | 2008-07-08 | E.I. Dupont De Nemours And Company | Poly(trimethylene terephthalate) composition and shaped articles prepared therefrom |
| EP2270065A3 (en) * | 2004-12-21 | 2011-03-09 | E. I. du Pont de Nemours and Company | Poly(trimethylene terephthalate) composition and shaped articles prepared therefrom |
| EP2156935A3 (en) * | 2005-10-28 | 2010-07-28 | Eastman Chemical Company | Restaurant smallware comprising polyester compositions formed from 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol |
| CN101100504B (zh) * | 2006-07-07 | 2010-04-21 | 新疆屯河聚酯有限责任公司 | 耐低压聚对苯二甲酸乙二醇酯树脂及其生产方法 |
| JP5449652B2 (ja) * | 2007-03-22 | 2014-03-19 | 株式会社クレハ | 芳香族ポリエステル系樹脂多層延伸成形体 |
| US20100044928A1 (en) * | 2008-08-22 | 2010-02-25 | E. I. Du Pont De Nemours And Company | Process for Shaped Articles from Polyester Blends |
| JP2014527924A (ja) * | 2011-08-25 | 2014-10-23 | プラスチパック パッケージング，インコーポレイテッド | 押出成形されたｐｅｔパリソン、容器、および方法 |
| ES2689778T3 (es) * | 2012-01-25 | 2018-11-15 | Plastipak Packaging, Inc. | Parisón extrudida de PET y recipiente fabricado |
| WO2013149157A1 (en) * | 2012-03-30 | 2013-10-03 | E. I. Du Pont De Nemours And Company | Polyesters and fibers made therefrom |
| KR102183791B1 (ko) * | 2015-04-24 | 2020-11-27 | 도요보 가부시키가이샤 | 2축 연신 폴리에스테르 필름 및 그 제조 방법 |
| EP3241865A1 (en) * | 2016-05-04 | 2017-11-08 | Clariant Plastics & Coatings Ltd | Composition for polyester hydrolytic stabilization |
| TW202024229A (zh) * | 2018-12-22 | 2020-07-01 | 遠東新世紀股份有限公司 | 具有阻氣性的聚酯組成物 |
| CN115505111A (zh) * | 2021-06-23 | 2022-12-23 | 杭州九阳小家电有限公司 | 一种采用生物基共聚酯杯体的食品加工机 |
| CN116285257B (zh) * | 2023-05-18 | 2023-07-18 | 广东永鑫华新型材料有限公司 | 一种耐高温超韧的改性pbt-pet复合材料的制备方法 |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2851788A1 (de) | 1978-11-30 | 1980-06-12 | Bayer Ag | Verfahren zur herstellung von aryloxiessigsaeuren |
| US4440922A (en) * | 1983-04-13 | 1984-04-03 | Eastman Kodak Co. | Polyester containers having improved gas barrier properties |
| US4501879A (en) * | 1984-03-26 | 1985-02-26 | Eastman Kodak Company | Polyesteramides and containers having improved gas barrier properties formed therefrom |
| US4552948A (en) | 1985-03-29 | 1985-11-12 | Eastman Kodak Company | Polyester resins capable of forming containers having improved gas barrier properties |
| US4663426A (en) * | 1985-03-29 | 1987-05-05 | Eastman Kodak Company | Polyester resins capable of forming containers having improved gas barrier properties |
| EP0335594A3 (en) * | 1988-03-26 | 1990-09-12 | Mitsubishi Chemical Corporation | Copolymerized polymer |
| US4935540A (en) | 1988-12-12 | 1990-06-19 | Sumner Jr Charles E | Process for the preparation of aryloxyacetic acid |
| JP2767944B2 (ja) | 1989-12-28 | 1998-06-25 | 三菱化学株式会社 | １，３―フェニレンジオキシジ酢酸の製造方法 |
| JP2870151B2 (ja) | 1990-08-02 | 1999-03-10 | 三菱化学株式会社 | １，３―フェニレンジオキシジ酢酸の製法 |
| JP2917498B2 (ja) | 1990-11-07 | 1999-07-12 | 三菱化学株式会社 | １，３―フェニレンジオキシジ酢酸の製法 |
| US5239045A (en) | 1990-12-27 | 1993-08-24 | Mitsubishi Kasei Corporation | Copolyester and hollow container and oriented film comprising the copolyester |
| JPH05295241A (ja) * | 1992-04-21 | 1993-11-09 | Denki Kagaku Kogyo Kk | ポリエステル樹脂組成物 |
-
1999
- 1999-06-11 AR ARP990102817A patent/AR019660A1/es unknown
- 1999-06-11 AR ARP990102818A patent/AR018672A1/es unknown
- 1999-06-11 AR ARP990102816A patent/AR017749A1/es unknown
- 1999-06-14 CA CA002334464A patent/CA2334464A1/en not_active Abandoned
- 1999-06-14 CN CN99809656A patent/CN1312837A/zh active Pending
- 1999-06-14 JP JP2000554801A patent/JP2002518537A/ja active Pending
- 1999-06-14 US US09/332,829 patent/US6254950B1/en not_active Expired - Fee Related
- 1999-06-14 EP EP99928624A patent/EP1095093A1/en not_active Withdrawn
- 1999-06-14 EP EP99928636A patent/EP1088034A1/en not_active Withdrawn
- 1999-06-14 JP JP2000554800A patent/JP2002518536A/ja active Pending
- 1999-06-14 CA CA002334828A patent/CA2334828A1/en not_active Abandoned
- 1999-06-14 WO PCT/US1999/013352 patent/WO1999065967A1/en not_active Ceased
- 1999-06-14 WO PCT/US1999/013371 patent/WO1999065989A1/en not_active Ceased
- 1999-06-14 JP JP2000554785A patent/JP2002518218A/ja active Pending
- 1999-06-14 BR BR9911256-6A patent/BR9911256A/pt not_active Application Discontinuation
- 1999-06-14 CA CA002332519A patent/CA2332519A1/en not_active Abandoned
- 1999-06-14 BR BR9911254-0A patent/BR9911254A/pt not_active Application Discontinuation
- 1999-06-14 WO PCT/US1999/013351 patent/WO1999065988A1/en not_active Ceased
- 1999-06-14 CN CN99807369A patent/CN1305503A/zh active Pending
- 1999-06-14 EP EP99928623A patent/EP1088033A1/en not_active Withdrawn
- 1999-06-14 CN CN99807462A patent/CN1305511A/zh active Pending
- 1999-06-14 BR BR9911262-0A patent/BR9911262A/pt not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| EP1095093A1 (en) | 2001-05-02 |
| AR018672A1 (es) | 2001-11-28 |
| EP1088033A1 (en) | 2001-04-04 |
| BR9911262A (pt) | 2001-03-13 |
| JP2002518536A (ja) | 2002-06-25 |
| WO1999065967A1 (en) | 1999-12-23 |
| CN1305511A (zh) | 2001-07-25 |
| BR9911254A (pt) | 2001-03-13 |
| CA2334828A1 (en) | 1999-12-23 |
| CN1312837A (zh) | 2001-09-12 |
| CN1305503A (zh) | 2001-07-25 |
| WO1999065988A1 (en) | 1999-12-23 |
| BR9911256A (pt) | 2001-03-13 |
| EP1088034A1 (en) | 2001-04-04 |
| CA2334464A1 (en) | 1999-12-23 |
| US6254950B1 (en) | 2001-07-03 |
| AR017749A1 (es) | 2001-10-24 |
| WO1999065989A1 (en) | 1999-12-23 |
| JP2002518537A (ja) | 2002-06-25 |
| JP2002518218A (ja) | 2002-06-25 |
| CA2332519A1 (en) | 1999-12-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AR018672A1 (es) | Una composicion de combinaciones de poliester /fenilendi(oxiacetico), acido copoliester, que tienen mejoradas propiedades de barrera de gases | |
| ATE505500T1 (de) | Polyesterzusammensetzungen mit cyclobutandiol mit hoher glasübergangstemperatur und daraus hergestellte artikel | |
| GB954110A (en) | Terephthalate copolyester adhesive compositions | |
| JP2002518536A5 (enExample) | ||
| KR890014602A (ko) | 공중합 폴리에스테르 | |
| BR0206971A (pt) | Produto de várias camadas | |
| KR950700360A (ko) | 고분자량 지방족 폴리에스테르 함유 폴리(1,4-사이클로헥실렌 디메틸렌 테레프탈레이트)를 주성분으로 하는 강화 성형 조성물(reinforced molding composition based on poly(1,4-cyclohexylene dimethylene terephthalate) containing a high molecular weight aliphatic polyester) | |
| KR970701756A (ko) | 방염성 재생 폴리에스테르 공중합체(flame-retardant recycled polyester copolymers) | |
| GB1026993A (en) | Polyester compositions for bonding glass fibre mats | |
| JP2008530328A5 (enExample) | ||
| KR960703963A (ko) | 형광성이 감소된 나프탈렌디카복실산 함유 중합체/할로겐 화합물 조성물(naphthalenedicarboxylic acid containing polymer/halogen compound compositions having reduced fluorescence) | |
| KR930000562A (ko) | 폴리에스테르 및 폴리에스테르 조성물의 제법 | |
| GB734416A (en) | Improvements relating to aromatic polyesters | |
| DE69125467D1 (de) | Formbares Polyesterharz mit hoher Stabilität gegen Schmelzwärme und daraus hergestellte Formteile | |
| GB1093897A (en) | Process of preparing polyester resin | |
| JP2012514091A (ja) | ポリエステル樹脂の製造方法 | |
| EP1499668A1 (en) | Hydrolysis resistant polyester elastomer compositions and related articles and methods | |
| KR960706465A (ko) | 아로일 그룹으로 치환된 나프탈렌 디카복실산 및 에스테르(naphthalene dicarboxylic acids and esters substituted with aroyl groups) | |
| US4041018A (en) | Thermoplastic carbonate-modified copolyesters and a process for their preparation | |
| GB1481857A (en) | Flame-resistant thermoplastic polyesters | |
| JP2008500428A5 (enExample) | ||
| MX9302145A (es) | Composicion de poliester y una zeolita | |
| MX2025011613A (es) | Copoliesteres modificados que tienen impacto de gota mejorado, metodos para hacerlos, y articulos moldeados hechos de ellos | |
| JP3021209B2 (ja) | ポリエステルの製造方法 | |
| ES443024A1 (es) | Procedimiento para la preparacion de poliesteres termoplas- ticos lineales. |