Fibrils and processes for the manufacture thereof

A process for producing a mass of entangled solvent swollen filaments from a high molecular weight polymer consisting essentially of the sequential steps of:

• a. dissolving said polymer in a solvent at a temperature above 100.degree. C. to prepare a solution thereof having a viscosity of at least about 50 centipoises;
• b. feeding said heated polymer solution to the inlet of a centrifugal spinning apparatus including therein:
• i. a housing,
• ii. a stationary disc-shaped plate attached to said housing,
• iii. a rotatable disc-shaped plate within said housing positioned closely adjacent to and parallel to but spaced from said stationary plate,
• iv. an inlet in the stationary disc-shaped plate adapted to feed liquid onto the rotatable disc-shaped plate,
• v. a plurality of flails pivotally attached to the circumference of said rotatable plate,
• vi. means for rotating said rotatable disc-shaped plate, and
• vii. an outlet in said housing;
• c. rotating said rotatable disc-shaped plate at a speed such that said flails are extended so as to define an annulus about the circumference of said rotating plate and said rotating plate has a tangential velocity of at least 100 cm/sec at the position where said polymer solution contacts said rotating disc-shaped plate so that said polymer solution is subjected to shearing forces, attenuated into liquid streams, and said liquid streams are fed into the annulus defined by said flails;
• d. feeding a coolant liquid into said housing and about said flails so as to contact the liquid polymer streams entering said annulus defined by said flails so as to cool said polymer streams to a temperature to precipitate substantially all said solute polymer as solvent swollen polymer filaments, the weight of said coolant liquid fed to said housing exceeding the weight of the polymer solution fed to the apparatus in step (b);
• and
• e. recovering a mass of entangled solvent swollen polymer filaments from said solvent;
• said polymer being selected from the group consisting of:
• 1. an olefin polymer having an inherent viscosity of at least 3.5 and selected from the group consisting of:
• i. an ethylene homopolymer,
• ii. a copolymer containing at least 90 weight % of polymerized ethylene and the balance a polymerized olefin hydrocarbon containing at least 4 carbon atoms,
• iii. a propylene homopolymer, and
• iv. a copolymer containing at least 50 weight % of polymerized propylene and the balance polymerized ethylene,
• 2. a mixture of olefin polymers of (1), and
• 3. a mixture of polymers containing at least 20 weight % of an olefin polymer of (1) and up to 80 weight % of a diluent polymer that is soluble at 100.degree. C. in the solvent employed in step (a).

A process for producing a mass of entangled solvent swollen filaments from a high molecular weight polymer consisting essentially of the sequential steps of:

• a. dissolving said polymer in a solvent at a temperature above 100.degree. C. to prepare a solution thereof having a viscosity of at least about 50 centipoises;
• b. feeding the heated polymer solution to the inlet of a rotatable centrifugal spinning device including therein;
• i. a housing,
• ii. an outer basket mounted within said housing,
• iii. means for cooling said outer basket,
• iv. a perforated inner drum mounted for rotation within said outer basket and spaced therefrom,
• v. an inlet in the housing communicating with the inner drum, and
• vi. an outlet in the housing;
• c. rotating said inner drum at a speed to centrifugally throw said polymer solution outwardly therefrom with a centrifugal acceleration of at least 25 times that of gravity so that said polymer solution is subjected to shearing forces and attenuated into liquid streams which impinge upon said outer basket;
• d. cooling the outer basket so that said polymer solution impinging thereon is cooled to a temperature to precipitate substantially all of said solute polymer as solvent swollen polymer filaments;
• and
• e. recovering said polymer as a mass of entangled solvent swollen filaments from said solvent;
• said polymer being selected from the group consisting of:
• 1. an olefin polymer having an inherent viscosity of at least 3.5 and selected from the group consisting of:
• i. an ethylene homopolymer,
• ii. a copolymer containing at least 90 weight % of polymerized ethylene and the balance a polymerized olefin hydrocarbon containing at least 4 carbon atoms,
• iii. a propylene homopolymer, and
• iv. a copolymer containing at least 50 weight % of polymerized propylene and the balance polymerized ethylene,
• 2. a mixture of olefin polymers of (1), and
• 3. a mixture of polymers containing at least 20 weight % of an olefin polymer of (1) and up to 80 weight % of a diluent polymer that is soluble at 100.degree. C. in the solvent employed in step (a).

A process for producing a mass of entangled solvent swollen filaments from a high molecular weight polymer consisting essentially of the sequential steps of:

• a. dissolving said polymer in a solvent at a temperature above 100.degree. C. to prepare a solution thereof having a viscosity of at least about 50 centipoises;
• b. forcing said heated polymer solution through an elongated die to shear said solution and thereby orient the polymer molecules therein;
• c. feeding the stream of polymer solution from said die into a cooling zone in which the stream of polymer solution is cooled to a temperature to precipitate substantially all of said solute polymer as solvent swollen polymer filaments;
• and
• d. recovering said polymer as a mass of entangled solvent swollen fine filaments from said solvent;
• said polymer being selected from the group consisting of:
• 1. an olefin polymer having an inherent viscosity of at least 3.5 and selected from the group consisting of:
• i. an ethylene homopolymer,
• ii. a copolymer containing at least 90 weight % of polymerized ethylene and the balance a polymerized olefin hydrocarbon containing at least 4 carbon atoms.
• iii. a propylene homopolymer, and
• iv. a copolymer containing at least 50 weight % of polymerized propylene and the balance polymerized ethylene,
• 2. a mixture of olefin polymers of (1), and
• 3. a mixture of polymers containing at least 20 weight % of an olefin polymer of (1) and up to 80 weight % of a diluent polymer that is soluble at 100.degree. C. in the solvent employed in step (a).

A process for producing fibrils suitable for the manufacture of water leaves from a high molecular weight polymer consisting essentially of the sequential steps of:

• a. dissolving said polymer in a solvent at a temperature above 100.degree. C. to prepare a solution thereof having a viscosity of at least about 50 centipoises;
• b. subjecting said heated polymer solution to shearing forces and attenuating said solution into liquid streams to orient the solute polymer molecules in said liquid streams while maintaining said polymer solution at a temperature sufficiently high to maintain substantially all of said polymer in solution;
• c. feeding said liquid streams into a cooling zone in which said streams are cooled to a temperature to precipitate substantially all said solute polymer as solvent swollen polymer filaments;
• d. recovering said polymer as a mass of entangled solvent swollen filaments from said solvent;
• e. beating said filaments in a liquid which is a non-solvent for the polymer for a time sufficient to break down said filaments into a plurality of individual fibrils;
• and
• f. separating said fibrils from said non-solvent liquid;
• said polymer being selected from the group consisting of:
• 1. an olefin polymer having an inherent viscosity of at least 3.5 and selected from the group consisting of:
• i. an ethylene homopolymer,
• ii. a copolymer containing at least 90 weight % of polymerized ethylene and the balance a polymerized olefin hydrocarbon containing at least 4 carbon atoms.
• iii. a propylene homopolymer, and
• iv. a copolymer containing at least 50 weight % of polymerized propylene and the balance polymerized ethylene,
• 2. a mixture of olefin polymers of (1), and
• 3. a mixture of polymers containing at least 20 weight % of an olefin polymer of (1) and up to 80 weight % of a diluent polymer that is soluble at 100.degree. C. in the solvent employed in step (a).

A process for producing fibrils suitable for the manufacture of water leaves from a high molecular weight polymer consisting essentially of the sequential steps of:

• a. dissolving said polymer in a solvent at a temperature above 100.degree. C. to prepare a solution thereof having a viscosity of at least about 50 centipoises;
• b. feeding said heated polymer solution to the inlet of a centrifugal spinning apparatus including therein:
• i. a housing,
• ii. a stationary disc-shaped plate attached to said housing,
• iii. a rotatable disc-shaped plate within said housing positioned closely adjacent to and parallel to but spaced from said stationary plate,
• iv. an inlet in the stationary disc-shaped plate adapted to feed liquid onto the rotatable disc-shaped plate,
• v. a plurality of flails pivotally attached to the circumference of said rotatable plate,
• vi. means for rotating said rotatable disc-shaped plate, and
• vii. an outlet in said housing;
• c. rotating said rotatable disc-shaped plate at a speed such that said flails are extended so as to define an annulus about the circumference of said rotating plate and said rotating plate has a tangential velocity of at least 100 cm/sec at the position where said polymer solution contacts said rotating disc-shaped plate so that said polymer solution is subjected to shearing forces, attenuated into liquid streams, and said liquid streams are fed into the annulus defined by said flails;
• d. feeding a coolant liquid into said housing and about said flails so as to contact the liquid polymer streams entering said annulus defined by said flails so as to cool said polymer streams to a temperature to precipitate substantially all said solute polymer as solvent swollen polymer filaments, the weight of said coolant liquid fed to said housing exceeding the weight of the polymer solution fed to the apparatus in step (b);
• e. recovering a mass of entangled solvent swollen polymer filaments from said solvent;
• f. beating said filaments in a liquid which is a nonsolvent for the polymer for a time sufficient to break down said filaments into a plurality of individual fibrils;
• and
• g. separating said fibrils from said nonsolvent liquid;
• said polymer being selected from the group consisting of:
• 1. an olefin polymer having an inherent viscosity of at least 3.5 and selected from the group consisting of:
• i. an ethylene homopolymer,
• ii. a copolymer containing at least 90 weight % of polymerized ethylene and the balance a polymerized olefin hydrocarbon containing at least 4 carbon atoms,
• iii. a propylene homopolymer, and
• iv. a copolymer containing at least 50 weight % of polymerized propylene and the balance polymerized ethylene,
• 2. a mixture of olefin polymers of (1), and
• 3. a mixture of polymers containing at least 20 weight % of an olefin polymer of (1) and up to 80 weight % of a diluent polymer that is soluble at 100.degree. C. in the solvent employed in step (a).

A process for producing fibrils suitable for the manufacture of water leaves from a high molecular weight polymer consisting essentially of the sequential steps of:

• a. dissolving said polymer in a solvent at a temperature above 100.degree. C. to prepare a solution thereof having a viscosity of at least about 50 centipoises;
• b. feeding the heated polymer solution to the inlet of a rotatable centrifugal spinning device including therein;
• i. a housing,
• ii. an outer basket mounted within said housing,
• iii. means for cooling said outer basket,
• iv. a perforated inner drum mounted for rotation within said outer basket and spaced therefrom,
• v. an inlet in the housing communicating with the inner drum, and
• vi. an outlet in the housing;
• c. rotating said inner drum at a speed to centrifugally throw said polymer solution outwardly therefrom with a centrifugal acceleration of at least 25 times that of gravity so that said polymer solution is subjected to shearing forces and attenuated into liquid streams which impinge upon said outer basket;
• d. cooling the outer basket so that said polymer solution impinging thereon is cooled to a temperature to precipitate substantially all of said solute polymer as solvent swollen polymer filaments;
• e. recovering said polymer as a mass of entangled solvent swollen filaments from said solvent;
• f. beating said filaments in a liquid which is a non-solvent for the polymer for a time sufficient to break down said filaments into a plurality of individual fibrils;
• and
• g. separating said fibrils from said non-solvent liquid;
• said polymer being selected from the group consisting of:
• 1. an olefin polymer having an inherent viscosity of at least 3.5 and selected from the group consisting of:
• i. an ethylene homopolymer,
• ii. a copolymer containing at least 90 weight % of polymerized ethylene and the balance a polymerized olefin hydrocarbon containing at least 4 carbon atoms,
• iii. a propylene homopolymer, and
• iv. a copolymer containing at least 50 weight % of polymerized propylene and the balance polymerized ethylene,
• 2. a mixture of olefin polymers of (1), and
• 3. a mixture of polymers containing at least 20 weight percent of an olefin polymer of (1) and up to 80 weight % of a diluent polymer that is soluble at 100.degree. C. in the solvent employed in step (a).

A process for producing fibrils suitable for the manufacture of water leaves from a high molecular weight polymer consisting essentially of the sequential steps of:

• a. dissolving a polymer in a solvent at a temperature above 100.degree. C. to prepare a solution thereof having a viscosity of at least about 50 centipoises;
• b. forcing said heated polymer solution through an elongated die to shear said solution and thereby orient the polymer molecules therein;
• c. feeding the stream of polymer solution from said die into a cooling zone in which the stream of polymer solution is cooled to a temperature to precipitate substantially all of said solute polymer as solvent swollen polymer filaments;
• d. recovering said polymer as a mass of entangled solvent swollen fine filaments from said solvent;
• e. chopping said solvent swollen filaments into discrete lengths;
• f. beating said chopped filaments in a liquid which is a nonsolvent for the polymer for a time sufficient to break down said filaments into a plurality of individual fibrils;
• and
• g. separating said fibrils from said nonsolvent liquid;
• said polymer being selected from the group consisting of:
• 1. an olefin polymer having an inherent viscosity of at least 3.5 and selected from the group consisting of:
• i. an ethylene homopolymer,
• ii. a copolymer containing at least 90 weight % of polymerized ethylene and the balance a polymerized olefin hydrocarbon containing at least 4 carbon atoms,
• iii. a propylene homopolymer, and
• iv. a copolymer containing at least 50 weight % of polymerized propylene and the balance polymerized ethylene,
• 2. a mixture of olefin polymers of (1), and
• 3. a mixture of polymers containing at least 20 weight % of an olefin polymer of (1) and up to 80 weight % of a diluent polymer that is soluble at 100.degree. C. in the solvent employed in step (a).