METHODS FOR CONTROLLING POLYMER PROPERTIES

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas-phase reactor by about 1° C. or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided. 1. A method of producing a polyolefin comprising:contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; andchanging a reaction temperature in the gas-phase reactor by about 1° C. or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more.2. The method of wherein the reduced chromium oxide catalyst has been reduced with an alkyl aluminum alkoxide.3. The method of wherein the alkyl aluminum alkoxide comprises diethyl aluminum ethoxide.4. The method of wherein the monomer comprises ethylene.5. The method of wherein the co-monomer comprises an alpha olefin comprising from 3 carbons to 20 carbons.6. The method of wherein the reaction temperature in the gas-phase reactor is changed by about 2° C. or more.7. The method of wherein the reaction temperature in the gas-phase reactor is changed by about 5° C. or more.8. The method of wherein the comonomer content of the polyolefin at substantially constant density is changed by about 5% or more.9. The method of wherein the comonomer content of the ...

POLYOLEFIN FILM WITH IMPROVED TOUGHNESS

A film formed from a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a co-monomer selected from butene monomers or 1-hexene, where the polyethylene copolymer has a density in the range of from about 0.935 to about 0.950 g/cmand an I/Iin a range of about 18.0 to about 30.0. The film formed from the polyethylene copolymer has a dart drop impact (g/m) that significantly greater as compared to a film of the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such films is also provided. 1. A film comprising: a polyethylene copolymer formed using a reduced chromium oxide catalyst , ethylene monomers and a co-monomer selected from 1-butene or 1-hexene , the polyethylene copolymer formed with the co-monomer to ethylene monomer mole ratio in a range of about 0.012 to about 0.04 to form the polyethylene copolymer having a density in the range of from about 0.9350 to about 0.950 g/cmand an I/Iin a range of about 18.0 to about 30.0 , wherein the polyethylene copolymer formed using the reduced chromium oxide catalyst provides an improvement in a dart drop impact (g/μm) of the film of 17 percent to 56 percent as compared to a film of the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst.2. The film of claim 1 , where the reduced chromium oxide catalyst is reduced with diethylaluminum ethoxide (DEAlE).3. The film of claim 1 , wherein the polyethylene copolymer has a melt index (I) of about 0.4 to about 1.0 g/10 min.4. The film of claim 1 , wherein the polyethylene copolymer has a flow index (I) of about 5.0 to about 25.0 g/10 min.5. The film of claim 1 , wherein the polyethylene copolymer has an I/Iof about 18.0 to about 28.0.6. The film of claim 1 , wherein the film has a dart drop impact of about 10.0 to about 20.0 g/μm.7. The film of claim 1 , wherein the polyethylene copolymer has a Mw≥about 100 claim 1 ...

Systems and Methods for Fabricating Polymers

The present invention is broadly directed to various methods and systems for gas and liquid phase polymer production. In certain embodiments, the methods are performed in conjunction with a polymerization reactor system such as gas phase reactor system or liquid phase reactor system. The invention is also broadly directed to various systems in which polymer properties are manipulated by addition of DEALE directly to a polymerization reactor system. 1. A method for producing a polymer , comprising:injecting a chromium oxide-based catalyst into a gas phase reactor system;contacting a gaseous monomer with the catalyst in the reactor system for polymerizing the monomer to form a polymer; andadding an alkyl aluminum alkoxide in situ to the reactor system in an effective amount for reducing a molecular weight of the polymer to about a target molecular weight.2. A method for producing a polyolefin , comprising:determining an initial set of operating conditions for producing a polyolefin in a fluidized bed reactor system including a temperature, a hydrogen concentration, an oxygen concentration and optionally a comonomer concentration;selecting a chromium oxide-based catalyst that has been reduced with diethylaluminum ethoxide (DEALE) based on a desired property of the polyolefin and the operating temperature;contacting a monomer with the catalyst in the fluidized bed reactor system;cooling a recycle stream of the fluidized bed reactor system for maintaining about the initial operating temperature;adding DEALE in situ to the reactor system in an effective amount for reducing a molecular weight of the polymer to about a target molecular weight;measuring a flow index or melt index of the polymer; andadjusting at least one condition from the initial set of operating conditions based on the measured flow index or melt index.3. The method according to or , wherein the catalyst is a chromium oxide on dehydrated silica.43. The method according to any one of - claims 1 , wherein ...

METHODS FOR CONTROLLING POLYMER PROPERTIES

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas-phase reactor by about 1° C. or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided. 115.-. (canceled)16. A method of producing a polyolefin comprising:{'sup': '2', 'contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises ethylene and a co-monomer, and wherein the polyolefin is characterized by (i) a modified-Charpy impact strength of about 20 kJ/mor more and (ii) an equivalent stress cracking resistance of about 50 hours or more determined by notched constant ligament stress.'}17. The method of wherein the modified-Charpy impact strength of the polyolefin is about 22 kJ/mto about 24 kJ/m.18. The method of wherein the equivalent stress cracking resistance of the polyolefin is about 60 hours or more.19. The method of wherein the reduced chromium oxide catalyst has been reduced with an alkyl aluminum alkoxide.20. The method of wherein the alkyl aluminum alkoxide comprises diethyl aluminum ethoxide.21. The method of wherein the monomer comprises ethylene.22. The method of wherein the co-monomer comprises an alpha olefin comprising from 3 carbons to 20 carbons.23. The method of wherein reaction temperature in the gas-phase reactor is increased to decrease comonomer content of the polyolefin.24. The method of wherein reaction temperature in the gas ...

Broad Molecular Weight Polyethylene Having Improved Properties

Disclosed herein is a polyolefin polymer having improved properties wherein the polymer is produced using a chromium based catalyst in combination with aluminum alkyl activators and co-catalysts. Also disclosed is a pipe comprising the inventive polymer and a film comprising the inventive polymer, each having improved properties over those known in the art.

Polyolefin film with improved toughness

A film formed from a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a co-monomer selected from butene monomers or 1-hexene, where the polyethylene copolymer has a density in the range of from about 0.935 to about 0.950 g/cm3 and an I21/I5 in a range of about 18.0 to about 30Ø The film formed from the polyethylene copolymer has a dart drop impact (g/µm) that significantly greater as compared to a film of the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such films is also provided.

Polyolefin film with improved toughness

A film formed from a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a co-monomer selected from butene monomers or 1-hexene, where the polyethylene copolymer has a density in the range of from about 0.935 to about 0.950 g/cm 3 and an I 21 /I 5 in a range of about 18.0 to about 30.0. The film formed from the polyethylene copolymer has a dart drop impact (g/μm) that significantly greater as compared to a film of the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such films is also provided.

Systems and methods for fabricating polymers

Disclosed herein are various methods and systems for gas and liquid phase polymer production. In certain embodiments, the methods comprise manipulating properties of polymers produced by adjusting the hydrogen feed rate.

Systems and methods for fabricating polymers

The present invention is broadly directed to various methods and systems for gas and liquid phase polymer production. In certain embodiments, the methods are performed in conjunction with a polymerization reactor system such as gas phase reactor system or liquid phase reactor system. The invention is also broadly directed to various systems in which polymer properties are manipulated by addition of DEALE directly to a polymerization reactor system.

systems and processes for polymer manufacturing

sistemas e processos para a fabricação de polímeros a presente invenção refere-se a processos e sistemas para a produção de polímero em fase gasosa e líquida. em certas modalidades, os processos compreendem a manipulação de propriedades dos polímeros produzidos por ajuste da taxa de alimentação de hidrogênio. Systems and processes for the manufacture of polymers The present invention relates to processes and systems for the production of gas and liquid phase polymer. In certain embodiments, the processes comprise manipulating properties of the polymers produced by adjusting the hydrogen feed rate.

Systems and methods for fabricating polymers

Disclosed herein are various methods and systems for gas and liquid phase polymer production. In certain embodiments, the methods comprise manipulating properties of polymers produced by adjusting the hydrogen feed rate.

Systems and Methods for Fabricating Polymers

The present invention is broadly directed to various methods and systems for gas and liquid phase polymer production. In certain embodiments, the methods are performed in conjunction with a polymerization reactor system such as gas phase reactor system or liquid phase reactor system. The invention is also broadly directed to various systems in which polymer properties are manipulated by addition of DEALE directly to a polymerization reactor system.

Polyolefin film with improved toughness

A film formed from a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a co-monomer selected from butene monomers or 1-hexene, where the polyethylene copolymer has a density in the range of from about 0.935 to about 0.950 g/cm 3 and an I 21 /I 5 in a range of about 18.0 to about 30.0. The film formed from the polyethylene copolymer has a dart drop impact (g/μm) that significantly greater as compared to a film of the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such films is also provided.

Systems and methods for fabricating polymers

Method for controlling polyolefin properties during polymerisation

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas- phase reactor by about 1o C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2 pcnt or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2 pcnt or more. Additional methods and compositions are also provided.

Methods for controlling polymer properties

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas-phase reactor by about 1° C. or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Methods for controlling polymer properties

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas-phase reactor by about 1° C. or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Systems and Methods for Fabricating Polymers

Disclosed herein are various methods and systems for gas and liquid phase polymer production. In certain embodiments, the methods comprise manipulating properties of polymers produced by adjusting the hydrogen feed rate.

Methods for controlling polymer properties

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas- phase reactor by about 1° C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

methods for controlling polymer properties

são divulgados aqui métodos de controlar as propriedades de polímero em processo de polimerização que utilizam um catalisador baseado em cromo. uma modalidade divulga um método de produzir uma poliolefina compreendendo: colocar em contato uma mistura de reação e um catalisador de óxido de cromo reduzido em um reator de fase gasosa para produzir a poliolefina, em que a mistura de reação compreende um monômero e um comonômero; e mudar a temperatura de reação no reator de fase gasosa em cerca de 1°c ou mais pela qual uma proporção molar de gás do comonômero para o monômero é mudada em cerca de 2% ou mais e um conteúdo de comonômero da poliolefina em densidade substancialmente constante é mudado em cerca de 2% ou mais. métodos adicionais e composições também são fornecidos. methods of controlling polymer properties in the polymerization process using a chromium-based catalyst are disclosed here. one embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a comonomer; and changing the reaction temperature in the gas phase reactor by about 1 ° c or more by which a molar ratio of gas from the comonomer to the monomer is changed by about 2% or more and a comonomer content of the polyolefin in substantially density constant is changed by about 2% or more. additional methods and compositions are also provided.

systems and processes for polymer manufacturing

Sistemas y métodos para fabricar polímeros

Un método para producir un polímero, que comprende: introducción de un catalizador con base de cromo en un sistema de reactor en fase gaseosa, introducción de hidrógeno al sistema de reactor, contacto de un monómero gaseoso con el catalizador en el sistema de reactor para formar un polímero, extracción de un polímero del sistema de reactor, donde el polímero extraído tiene un primer índice de flujo,procesamiento del polímero extraído, donde el polímero procesado tiene un segundo índice de flujo, y determinación del cambio en el índice de flujo, donde el cambio en el índice de flujo es la diferencia entre el segundoíndice de flujo y el primer índice de flujo; en el que la cantidad de hidrógeno introducida dentro del sistema de reactor es ajustada para manipular el cambioen el índice de flujo.

FILM AND METHOD TO MAKE A FILM HAVING IMPROVED DART IMPACT

FILME DE POLIOLEFINA COM TENACIDADE MELHORADA Um filme formado de um copolímero de polietileno usando um catalisador de óxido de cromo reduzido, monômeros de etileno e um comonômero selecionado de monômeros de buteno ou 1-hexeno, onde o copolímero de polietileno tem uma densidade na faixa de cerca de 0,935 a cerca de 0,950 g/cm3 e um I21/I5 numa faixa de cerca de 18,0 a cerca de 30,0. O filme formado a partir do copolímero de polietileno tem um impacto de queda de dardo (g/µm) significativamente maior em comparação com um filme do copolímero de polietileno formado usando um catalisador de cromato de silil no lugar do catalisador de óxido de cromo reduzido. Um método de fazer tais filmes também é fornecido. POLYOLEFIN FILM WITH IMPROVED TENACITY A film formed from a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a comonomer selected from butene or 1-hexene monomers, where the polyethylene copolymer has a density in the range of about 0.935 to about 0.950 g/cm 3 and an I21/I5 in a range of about 18.0 to about 30.0. The film formed from the polyethylene copolymer has a significantly higher dart drop impact (g/µm) compared to a film from the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such films is also provided.

Method for producing polyolefins

MÉTODOS PARA CONTROLAR AS PROPRIEDADES DE POLÍMERO. São divulgados aqui métodos de controlar as propriedades de polímero em processo de polimerização que utilizam um catalisador baseado em cromo. Uma modalidade divulga um método de produzir uma poliolefina compreendendo: colocar em contato uma mistura de reação e um catalisador de óxido de cromo reduzido em um reator de fase gasosa para produzir a poliolefina, em que a mistura de reação compreende um monômero e um comonômero; e mudar a temperatura de reação no reator de fase gasosa em cerca de 1°C ou mais pela qual uma proporção molar de gás do comonômero para o monômero é mudada em cerca de 2% ou mais e um conteúdo de comonômero da poliolefina em densidade substancialmente constante é mudado em cerca de 2% ou mais. Métodos adicionais e composições também são fornecidos. METHODS TO CONTROL POLYMER PROPERTIES. Disclosed herein are methods of controlling polymer properties in a polymerization process that utilize a chromium-based catalyst. One embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a comonomer; and changing the reaction temperature in the gas phase reactor by about 1°C or more whereby a molar ratio of gas of comonomer to monomer is changed by about 2% or more and a comonomer content of the polyolefin in density substantially constant is changed by about 2% or more. Additional methods and compositions are also provided.

Methods for controlling polymer properties

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas- phase reactor by about 1° C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Method for controlling polyolefin properties during polymerisation.

La presente invención se refiere a métodos para controlar las propiedades de polímeros en procesos de polimerización que utilizan un catalizador a base de cromo. Una modalidad describe un método para producir una poliolefina que comprende: poner en contacto una mezcla de reacción y un catalizador de óxido de cromo reducido en un reactor de fase gaseosa para producir la poliolefina, en donde la mezcla de reacción comprende un monómero y un comonómero; y cambiar una temperatura de reacción en el reactor de fase gaseosa por aproximadamente 1°C o más por lo cual una relación molar de gas del comonómero a monómero se cambia por aproximadamente 2% o más y un contenido de comonómero de la poliolefina sustancialmente a densidad constante se cambia por aproximadamente 2% o más. También se proporcionan métodos y composiciones adicionales.

Methods for controlling polymer properties

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas- phase reactor by about 1° C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Method for controlling polyolefin properties during polymerisation

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas- phase reactor by about 1° C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Method for controlling polyolefin properties during polymerisation

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas- phase reactor by about 1ø C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2 pcnt or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2 pcnt or more. Additional methods and compositions are also provided.

Polyolefin film with improved toughness

Polyolefin film with improved toughness

A film formed from a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a co-monomer selected from butene monomers or 1-hexene, where the polyethylene copolymer has a density in the range of from about 0.935 to about 0.950 g/cm3 and an I21/I5 in a range of about 18.0 to about 30.0. The film formed from the polyethylene copolymer has a dart drop impact (g/μm) that significantly greater as compared to a film of the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such films is also provided.

enhanced toughness polyolefin film

filme de poliolefina com tenacidade melhorada um filme formado de um copolímero de polietileno usando um catalisador de óxido de cromo reduzido, monômeros de etileno e um comonômero selecionado de monômeros de buteno ou 1-hexeno, onde o copolímero de polietileno tem uma densidade na faixa de cerca de 0,935 a cerca de 0,950 g/cm3 e um i21/i5 numa faixa de cerca de 18,0 a cerca de 30,0. o filme formado a partir do copolímero de polietileno tem um impacto de queda de dardo (g/µm) significativamente maior em comparação com um filme do copolímero de polietileno formado usando um catalisador de cromato de silil no lugar do catalisador de óxido de cromo reduzido. um método de fazer tais filmes também é fornecido. enhanced toughness polyolefin film a film formed of a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a comonomer selected from butene or 1-hexene monomers, where the polyethylene copolymer has a density in the range of about 0.935 to about 0.950 g / cm3 and an i21 / i5 in a range of about 18.0 to about 30.0. The film formed from the polyethylene copolymer has a significantly higher dart drop impact (g / µm) compared to a polyethylene copolymer film formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such movies is also provided.

Systems and methods for fabricating polymers

Disclosed herein are various methods and systems for gas and liquid phase polymer production. In certain embodiments, the methods comprise manipulating properties of polymers produced by adjusting the hydrogen feed rate.

Methods for controlling polymer properties

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas- phase reactor by about 1° C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Methods for controlling polymer properties

A method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises ethylene and a comonomer, and wherein the polyolefin is characterized by (i) a modified-Charpy impact strength of about 20 kJ/m 2 or more and (ii) an equivalent stress cracking resistance of about 50 hours or more determined by notched constant ligament stress.

Methods for controlling polymer properties

Method for controlling polyolefin properties during polymerisation

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas phase reactor by about 1?C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Polyolefin film with improved toughness

A film formed from a polyethylene copolymer using a reduced chromium oxide catalyst, ethylene monomers and a co-monomer selected from butene monomers or 1-hexene, where the polyethylene copolymer has a density in the range of from about 0.935 to about 0.950 g/cm3 and an I21/I5 in a range of about 18.0 to about 30Ø The film formed from the polyethylene copolymer has a dart drop impact (g/µm) that significantly greater as compared to a film of the polyethylene copolymer formed using a silyl chromate catalyst in place of the reduced chromium oxide catalyst. A method of making such films is also provided.

Methods for controlling polymer properties

A method of producing a polyolefin comprising:contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises ethylene and a comonomer, and wherein the polyolefin is characterized by (i) a modified-Charpy impact strength of about 20 kJ/m² or more and (ii) an equivalent stress cracking resistance of about 50 hours or more determined by notched constant ligament stress.

Methods for controlling polymer properties

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas-phase reactor by about 1 C or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided.

Métodos para controlar las propiedades de los polímeros

En el presente documento se describen métodos para controlar las propiedades del polímero en procesos de polimerización que utilizan un catalizador a base de cromo. Una realización describe un método para producir una poliolefina que comprende: poner en contacto una mezcla de reacción y un catalizador de óxido de cromo reducido en un reactor en fase gaseosa para producir la poliolefina, en el que la mezcla de reacción comprende un monómero y un comonómero; y cambiar la temperatura de reacción en el reactor en fase gaseosa en aproximadamente 1°C o más, con lo que la relación molar de gas del comonómero al monómero cambia en aproximadamente un 2% o más y el contenido de comonómero de la poliolefina en sustancialmente La densidad constante cambia en aproximadamente un 2% o más. También se proporcionan métodos y composiciones adicionales. (Traducción automática con Google Translate, sin valor legal)