Sea-island type composite multifilament, ultrafine multifilament, and ultrafine fiber structure

Abstract

Provided are a sea-island type composite multifilament which includes a thermoplastic elastomer resin as an island component, and an ultrafine multifilament prepared from such a sea-island type composite multifilament. The sea-island type composite multifilament includes an island component and a sea component. The island component includes a thermoplastic elastomer resin (A) having at least one of a Shore A hardness of 90 or less, a Shore D hardness of 60 or less, or a Rockwell hardness (R scale) of 70 or less. The sea component includes a water-soluble or easily alkali-soluble thermoplastic resin (B). The sea-island type composite multifilament has an average single island diameter of 8000 nm or less.

What is claimed is: 
     
         1 . A sea-island type composite multifilament comprising an island component and a sea component, the island component comprising a thermoplastic elastomer resin (A) having at least one of a Shore A hardness of 90 or less, a Shore D hardness of 60 or less, or a Rockwell hardness (R scale) of 70 or less, the sea component comprising a water-soluble or easily alkali-soluble thermoplastic resin (B), and the sea-island type composite multifilament having an average single island diameter of 8000 nm or less. 
     
     
         2 . The sea-island type composite multifilament according to  claim 1 , wherein the thermoplastic resin (B) of the sea component comprises a modified polyvinyl alcohol-based polymer in which a unit derived from an α-olefins and/or a vinyl ether is contained in a polyvinyl alcohol-based polymer moiety. 
     
     
         3 . The sea-island type composite multifilament according to  claim 1 , wherein the number of islands in the sea-island type composite multifilament is from 3 to 200, and the sea-island type composite multifilament has a composite mass ratio (sea component:island component) between the sea component and the island component of from 20:80 to 70:30. 
     
     
         4 . The sea-island type composite multifilament according to  claim 1 , wherein the thermoplastic elastomer resin (A) comprises a polyamide-based elastomer resin or a polyester-based elastomer resin. 
     
     
         5 . A fiber structure comprising, at least in part thereof, a sea-island type composite multifilament according to  claim 1  and/or a cut fiber thereof. 
     
     
         6 . An ultrafine multifilament comprising a thermoplastic elastomer resin (A) having at least one of a Shore A hardness of 90 or less, a Shore D hardness of 60 or less, or a Rockwell hardness (R scale) of 70 or less, the ultrafine multifilament having a coefficient of fiber-to-metal dynamic friction of 0.30 or more. 
     
     
         7 . The ultrafine multifilament according to  claim 6 , wherein the ultrafine multifilament has a single filament fineness of from 0.005 to 0.5 dtex. 
     
     
         8 . An ultrafine fiber structure comprising, at least in part thereof, an ultrafine multifilament according to  claim 6  and/or a cut fiber thereof. 
     
     
         9 . The ultrafine fiber structure according to  claim 8 , wherein the ultrafine fiber structure comprises a woven fabric or a knitted fabric. 
     
     
         10 . A process for producing an ultrafine multifilament, the process comprising at least a step of dissolving a thermoplastic resin (B) to be removed from a sea-island type composite multifilament according to  claim 1 . 
     
     
         11 . A process for producing an ultrafine fiber structure, the process comprising dissolving a thermoplastic resin (B) to be removed from a fiber structure according to  claim 5 .