Fina Technology, Inc.

Aiko Hanyu

William Rusty Wheat

Edwar Shoukri Shamshoum

Sehyun Kim

Mark Miller

Scott Cooper

Ben Hicks

Theodore G Harris, Iii

A heat-seal polymer film and method of forming such film is provided. The heat-seal film is formed from metallocene-catalyzed isotactic random copolymers of propylene and at least one other Cto Calpha olefin, such as ethylene random. Such films show improved heat-seal characteristics, such as reduced seal initiation temperatures (SIT's) and improved heat-seal strength, as well as other improved properties.

Heat-seal films and method of manufacture

The present invention relates to the improvement of metal bond strength in polypropylene films surface treated at higher levels through the addition to the basic isotactic polypropylene (iPP) polymer of an amount of syndiotactic polypropylene (sPP) in an amount no more than about 10 percent by weight and preferably in an amount between about 0.5 percent and about 8 percent by weight. The invention encompasses both the resulting metallized polypropylene films with enhanced bond strength and the process for producing such films. The prescribed use provides improved bonding properties over a simple non-blended isotactic polypropylene homopolymer, while maintaining at acceptable levels the optical and physical characteristics of a film made from non-blended iPP homopolymer. At increasing percentages of sPP above the preferred levels, bond strength continues to increase, but a deterioration in other properties may be noted, particularly in the optical property haze.

Metal bond strength in polypropylene films

The present invention is for the improvement of inter-layer bonding strength in polypropylene films through the addition of ethylene as a mini-random copolymer in an amount of no more than about 1 weight percent, more preferably no more than about 0.7 weight percent, and most preferably between about 0.3 weight percent to about 0.5 weight percent or even amounts less than about 0.2 weight percent. The invention allows the improvement of inter-layer bond strength in multi-layer films resulting specifically in improved heat seal strength. The invention encompasses both the resulting films with enhanced heat seal strength and the process for producing such films. In the preferred embodiment, the proposed mini-random copolymer is formed into a film layer used in place of a propylene homopolymer layer, providing improved bonding properties over a film formed of polypropylene homopolymer, while maintaining at acceptable levels the physical and optical characteristics of a film layer made from a propylene homopolymer, such as stiffness.

Heat-seal strength in polyolefin films

A multilayer polyolefin film of the type suitable for packaging application in which heat seals are formed, and in its preparation the multilayer film comprises a flexible substrate layer formed of a crystalline thermoplastic polymer having an interface surface. A heat-sealable surface layer is bonded to the interface surface of the substrate layer and is formed of a syndiotactic propylene polymer effective to produce a heat seal with itself at a sealing temperature of less than 110&deg; C. The surface layer has a thickness which is less than the thickness of the substrate layer. The heat-seal layer can be formed of syndiotactic polypropylene polymerized in the presence of a syndiospecific metallocene catalyst and having a melt flow index of less than 2 grams/10 minutes. The multilayer film can take the form of a a biaxially-oriented film. In the production of the multilayer film incorporating a substrate layer and a heat-sealable surface layer, a crystalline thermoplastic polymer is extruded and formed into a substrate layer film. A second polymer comprising a syndiotactic propylene polymer which is effective to form a heat-sealable surface layer is extruded to form a surface layer that is bonded to the interface of the substrate layer at a temperature within the range of 150-260&deg; C.

Heat-sealable films

A process for the production of biaxially-oriented polypropylene film involving the provision of a polypropylene polymer produced by the polymerization of propylene in the presence of a metallocene catalyst characterized by a bridged racemic bis(indenyl) ligand substituted at the proximal position. The polypropylene contains 0.5 to 2% 2,1 insertions and has an isotacticity of at least 96% meso pentads and at least 99% meso diads. The film is formed by stressing the polymer produced from a slot die in the machine direction at a stretch ratio of about 5 or 6 and in the transverse direction at a stretch ratio of about 8 or 9 to produce a biaxially-oriented film having a non-uniform melt temperature of a peak value of less than 160&deg; C. The polypropylene polymer has meltflow index of less than 5 grams per 10 minutes and has an average molecular weight within the range of 100,000-400,000 grams per mole. The film, when configured having a thickness of 18 microns, is characterized by a machine direction secant modulus of at least 1400 MPa, a transverse direction secant modulus of at least 2200 MPa, a kinetic film-to-film co-efficient of friction of no more than 0.5, and permeabilities to water and oxygen of no more than 2.6 g/m /d and 2400 c /m /d, respectively. The film is further characterized by shrinkage factors of at least 8% in a transverse dimension and at least 16% in a transverse direction when heated to a temperature of at least 140&deg; C.

Biaxially-oriented metallocene-based polypropylene films

The present invention relates to the improvement of metal bonding strength in polypropylene films through the addition of ethylene in a mini-random ethylene-propylene copolymer in an amount of no more than about 1 weight percent, more preferably no more than about 0.7 weight percent, and most preferably between about 0.3 weight percent and about 0.5 weight percent, or even amounts between about 0.05 weight percent and about 0.2 weight percent. The invention allows the improvement of metal bond strength in metallizable films. The invention encompasses both the resulting films with enhanced metal bond strength and the process for producing such films. In the preferred embodiment, the proposed mini-random copolymer is formed into a film layer used in place of a propylene homopolymer layer, providing improved bonding properties over a simple polypropylene homopolymer, while maintaining at acceptable levels the physical and optical characteristics of a film layer made from a propylene homopolymer, such as stiffness.

Metal bond strength in polyolefin films

Provided is polyolefin composition, the majority of which is highly isotactic polypropylene, comprising the property of heat of melting (&Dgr;H,) greater than or equal to about 89 J/g.

Compositions useful for tough, high crystallinity films

The present invention relates to improved processability of polyolefin films through the addition to the basic isotactic polypropylene (iPP) polymer of a syndiotactic polypropylene (sPP) in an amount within the range of about 2 to 10 weight percent and of a resin or rosin modifier in an amount within the range of 1 to 30 weight percent. Preferably, the composition could contain syndiotactic propylene in an amount within the range of about 2 to 5 weight percent. Preferably, about 3 weight percent of syndiotactic propylene is present in the polyolefin composition. The resin or rosin modifier could, preferably, be present in an amount within the range of 5 to 10 weight percent. Preferably, the composition should contain about 10 weight percent of the modifier. The present invention encompasses both the resulting polyolefin films and the process for producing such films. The improved processability of the film includes fewer webs breaks and drawability at higher line speeds, resulting in fewer shut downs of the processing line and a decrease in manufacturing time. These improvements are measured in terms of variable machine direction orientation draw ratios and transverse direction orientation oven temperatures.

Compositions for improved orientation processing

A process for the production of biaxially-oriented polypropylene film involving the provision of a polypropylene polymer produced by the polymerization of propylene in the presence of a metallocene catalyst characterized by a bridged racemic bis(indenyl) ligand substituted at the proximal position. The polypropylene contains 0.5 to 2% 2,1 insertions and has an isotacticity of at least 96% meso pentads and at least 99% meso diads. The film is formed by stressing the polymer produced from a slot die in the machine direction at a stretch ratio of about 5 or 6 and in the transverse direction at a stretch ratio of about 8 or 9 to produce a biaxially-oriented film having a non-uniform melt temperature of a peak value of less than 160.degree. C. The polypropylene polymer has meltflow index of less than 5 grams per 10 minutes and has an average molecular weight within the range of 100,000-400,000 grams per mole. The film, when configured having a thickness of 18 microns, is characterized by a machine direction secant modulus of at least 1400 MPa, a transverse direction secant modulus of at least 2200 MPa, a kinetic film-to-film co-efficient of friction of no more than 0.5, and permeabilities to water and oxygen of no more than 2.6 g/m.sup.2 /d and 2400 c.sup.3/ m.sup.2 /d, respectively. The film is further characterized by shrinkage factors of at least 8% in a transverse dimension and at least 16% in a transverse direction when heated to a temperature of at least 140.degree. C.

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Houston, TX, United States of America

Aiko Hanyu