Abstract A process is described for the intermittent autogenous bonding of a continuous filament web wherein the filaments have a low degree of crystallinity. In one embodiment, the process involves passing the web directly through a nip formed by a smooth hard surfaced roll and a roll containing raised points on its surface with both rolls being maintained at a temperature near the softening point of the filaments. The speed of the web through the nip, the roll size and the configuration of the raised points are coordinated such that the surface temperature of the web is not substantially increased before maximum pressure has been developed in the nip, but then is rapidly raised to a point where surface fusion is effected before a significant increase in filament crystallinity occurs. Webs prepared as illustrated possess a desirable combination of surface abrasion resistance and strength.
A nonwoven continuous filament web of polypropylene filaments having a basis weight of about 1-3 oz./yd. 2 , a surface abrasion resistance on both sides thereof of at least about 20, and basis weight normalized grab tensile strength of at least about 20 lbs./(ox./yd. 2 ), said web being further characterized by the presence of intermittent compressed autogenous bond regions of a size and density to provide textile-like qualities which extend through the thickness of the web with the filaments on both outer surfaces of the bond regions being substantially fused to give a film-like appearance and with the filaments within the interior of the web between both said outer fused surfaces of the bond regions being deformed without substantial fusion to provide delamination resistance.
Claim 2
Dependent Claim
125 words
A nonwoven continuous filament web of polypropylene filaments having a basis weight of about 1-3 oz./yd. 2 , a surface abrasion resistance on both sides thereof of at least about 20, and basis weight normalized grab tensile strength of at least about 20 lbs./(ox./yd. 2 ), said web being further characterized by the presence of intermittent compressed autogenous bond regions of a size and density to provide textile-like qualities which extend through the thickness of the web with the filaments on both outer surfaces of the bond regions being substantially fused to give a film-like appearance and with the filaments within the interior of the web between both said outer fused surfaces of the bond regions being deformed without substantial fusion to provide delamination resistance.
Claim 3
Dependent Claim
41 words
The web of claim 1 having a basis weight of about 1.25 - 2.5 oz./yd. 2 wherein the compressed bond regions are present in a density of about 100 - 500/in. 2 and occupy about 10-25% of the web surface area.
Claim 4
Dependent Claim
19 words
The web of claim 1 wherein the surface abrasion resistance on both sides thereof is at least about 50.