Method for producing a mixed fiber spunbonded nonwoven web
A mixed fiber spunbonded nonwoven fabric which comprises 90 to 10% by weight of a long fiber of thermoplastic resin (A) that has been hydrophilization-treated and 10 to 90% by weight of a long fiber of thermoplastic elastomer (B) and which has a strength ratio [the ratio of a strength at 20% of an elongation at a maximum strength (elongation at a maximum point) to the maximum strength] in at least one direction of not more than 40% and a bulk density of 0.10 to 0.40 g/cm 3 . The fabric can exhibit excellent initial hydrophilicity, long-lasting hydrophilicity, liquid dispersibility, liquid transpiration property, moisture permeability, breathability, softness, resistance to fluff, stretchability and touch, and low stickiness, and is suitable for sheets constituting absorbent articles such as sanitary napkins, panty liners, incontinence pads, and disposable diapers. A production method is also provided.
1. A method for producing a mixed fiber spunbonded nonwoven fabric comprising the steps of partially heat fusing a web which comprises 90 to 10% by weight of a long fiber of thermoplastic resin (A) that has been hydrophilization-treated and 10 to 90% by weight of a long fiber of thermoplastic elastomer (B), stretching the web in at least one direction and relaxing the stretched web, and pressing the relaxed web.
2. The method for producing a mixed fiber spunbonded nonwoven fabric according to claim 1 , wherein the pressing is carried out on not less than 20% of the area of the relaxed web.
3. The method for producing a mixed fiber spunbonded nonwoven fabric according to claim 1 , wherein the pressing is carried out at a melting point of the long fiber of thermoplastic resin (A)−100° C. through a melting point of the long fiber of thermoplastic resin (A)−10° C., and at a linear pressure of 20 N/cm or higher.
4. The method for producing a mixed fiber spunbonded nonwoven fabric according to claim 1 , wherein the mixed fiber spunbonded nonwoven fabric has a strength ratio [the ratio of a strength at 20% of an elongation at a maximum strength (elongation at a maximum point) to the maximum strength] in at least one direction of not more than 40% and a bulk density of 0.10 to 0.40 g/cm 3 .
5. The method for producing a mixed fiber spunbonded nonwoven fabric according to claim 1 , wherein the thermoplastic resin (A) is a propylene polymer, and the thermoplastic elastomer (B) is a thermoplastic polyurethane elastomer.
6. The method for producing a mixed fiber spunbonded nonwoven fabric according to claim 1 , wherein the thermoplastic resin (A) that has been hydrophilization-treated is obtained by adding 0.1 to 10 parts by weight of a nonionic surface-active agent to 100 parts by weight of the thermoplastic resin (A).