초록 ▼

A process is provided for producing a bonded nonwoven sheet from a lightly consolidated fibrous polyolefin sheet wherein the sheet is preheated on one or more preheating rolls, is bonded in one or more calendering nips, and is cooled on one or more cooling rolls. The process is used to make bonded p

A process is provided for producing a bonded nonwoven sheet from a lightly consolidated fibrous polyolefin sheet wherein the sheet is preheated on one or more preheating rolls, is bonded in one or more calendering nips, and is cooled on one or more cooling rolls. The process is used to make bonded polyolefin fibrous sheets that are smooth, are substantially impermeable to air and water, and are moisture vapor permeable.

대표청구항 ▼

[ What is claimed is:] [1.] A process for producing a highly bonded nonwoven sheet from a lightly consolidated fibrous sheet comprised of at least 50% by weight of polyolefin polymer, comprising the steps of:providing the lightly consolidated fibrous polyolefin sheet to a first preheating roll havin

[ What is claimed is:] [1.] A process for producing a highly bonded nonwoven sheet from a lightly consolidated fibrous sheet comprised of at least 50% by weight of polyolefin polymer, comprising the steps of:providing the lightly consolidated fibrous polyolefin sheet to a first preheating roll having an outer surface rotating at a linear surface speed, said first preheating roll outer surface being heated to a temperature within 15.degree. C. of the melting temperature of the sheet;contacting at least one face of the sheet with the heated surface of the first preheating roll and heating the sheet;transferring said heated sheet from the first preheating roll to a rotating first heated calender roll, said first heated calender roll having a diameter of less than 102 cm and having an outer heated surface with a linear surface speed not less than the linear surface speed of the first preheating roll and not more that 2% faster than the linear surface speed of the first preheating roll, said outer heated surface of said first heated calender roll being maintained at a temperature within 10.degree. C. of the melting temperature of the sheet material;contacting a surface of the sheet with said outer heated surface of the first heated calender roll;while said sheet is in contact with said first heated calender roll, passing said sheet through a first nip formed between said first heated calender roll and a back-up roll, said first nip imparting an average nip pressure of at least 18 kg/linear cm on the sheet;transferring said calendered sheet from the first heated calender roll to a first cooling roll, said first cooling roll having an outer cooling surface rotating at a linear surface speed not less than the linear surface speed of the first heated calender roll, said outer cooling surface of said cooling roll being maintained at a temperature at least 20.degree. C. below the melting point of the sheet material;contacting the calendered sheet with the outer cooling surface of the first cooling roll for a period sufficient to cool the sheet to a temperature below the melting temperature of the sheet material and stabilize the sheet material as a fully bonded sheet; andremoving said fully bonded sheet from said cooling roll.