Thermally bondable fiber for high strength non-woven fabrics

A composition comprising at least one substantially linear polypropylene having a melt flow rate of about 0.5-30, and at least one substantially linear polypropylene having a melt flow rate of about 60-1000.

A polypropylene fiber comprising a mixture of at least two components, said at least two components comprising at least one first component of substantially linear polypropylene having a melt flow rate of about 0.5-30, and at least one second component of substantially linear polypropylene having a melt flow rate of about 60-1000, and the fiber having an average melt flow rate of about 5-40.

A polypropylene fiber, said fiber having an average melt flow rate of about 5-40 and containing at least about 3.0% of at least one substantially linear polypropylene having a melt flow rate of about 200-1000.

A polypropylene fiber, said fiber having an average rheological polydispersity index of at least about 4.5, and containing at least about 3.0% of at least one substantially linear polypropylene having a melt flow rate of about 200-1000.

A polypropylene fiber, said fiber having a zero shear viscosity of at least about 2.0.times.10.sup.4 poise, and a viscoelastic constant of at least about 1.50.

A thermally bondable fiber produced by a process for spinning polypropylene filaments comprising:

• melt spinning a polypropylene composition having a broad molecular weight distribution comprising at least one substantially linear polypropylene having a melt flow rate of about 0.5-30, and at least one substantially linear polypropylene having a melt flow rate of about 60-1000 through at least one spinnerette to form molten polypropylene filaments;
• and
• quenching the molten polypropylene filaments to obtain polypropylene filaments having an average rheological polydispersity index of at least about 5.0.

A thermally bondable fiber produced by a process for spinning polypropylene filaments comprising:

• melt spinning a polypropylene composition having a broad molecular weight distribution through at least one spinnerette at a spinning speed of about 30 to 200 meters per minute to form molten polypropylene filaments;
• and
• quenching the molten polypropylene filaments.

A thermally bondable fiber produced by a process for producing thermobondable filaments having an average rheological polydispersity index of at least about 4.5 which is substantially maintained throughout the process, comprising:

• melt spinning a polypropylene composition having a broad molecular weight distribution comprising at least one substantially linear polypropylene having a melt flow rate of about 0.5-30, and at least one substantially linear polypropylene having a melt flow rate of about 60-1000, and having an average rheological polydispersity index of at least about 4.5 through at least one spinnerette to form molten polypropylene filaments;
• and
• quenching the molten polypropylene filaments under conditions to obtain polypropylene filaments having an average rheological polydispersity index of at least about 4.5.

A thermally bondable fiber produced by a process for producing thermobondable filaments having an average rheological polydispersity index of at least about 4.5 which is substantially maintained throughout the process, comprising:

• melt spinning a polypropylene composition having a broad molecular weight distribution comprising at least one substantially linear polypropylene having a melt flow rate of about 0.5-30, and at least one substantially linear polypropylene having a melt flow rate of about 60-1000, and having an average rheological polydispersity index of at least about 4.5 through at least one spinnerette to form molten polypropylene filaments;
• and
• quenching the molten polypropylene filaments under conditions to obtain a substantially uniform morphology of the quenched polypropylene filaments having an average rheological polydispersity index of at least about 4.5.

A thermally bondable fiber produced by a process for spinning polypropylene filaments comprising:

• melt spinning a polypropylene composition having a broad molecular weight distribution through at least one spinnerette at a spinning speed of about 30 to 200 meters per minute to form molten polypropylene filaments;
• and
• quenching the molten polypropylene filaments to obtain polypropylene filaments having an average rheological polydispersity index of at least about 4.5.

A thermally bondable fiber produced by a process for spinning polypropylene filaments comprising:

• melt spinning a polypropylene composition having a broad molecular weight distribution, and containing at least about 3.0% of at least one polypropylene having a melt flow rate of about 60-1000, through at least one spinnerette at a spinning speed of about 30 to 200 meters per minute to form molten polypropylene filaments;
• and
• quenching the molten polypropylene filaments to obtain polypropylene filaments having an average melt flow rate of about 5-40.