초록 ▼

Improvement to the die and method of forming meltblown fibers and webs using a relatively cool fluid for meltblowing. Thermoplastic polymers such as polyolefins, polyamides, polyesters and the like are spun in accordance with the meltblowing process and contacted by a fluid which forms fibers and at

Improvement to the die and method of forming meltblown fibers and webs using a relatively cool fluid for meltblowing. Thermoplastic polymers such as polyolefins, polyamides, polyesters and the like are spun in accordance with the meltblowing process and contacted by a fluid which forms fibers and attenuates them. In accordance with the invention, the fluid is substantially cooler than the molten polymer and permits formation of webs at shorter forming distances greatly improving web formation. In addition, the costs of manufacture are improved since heating of the attenuating fluid may be reduced or avoided. In a particularly preferred embodiment, the die is provided with insulation between the attenuating fluid and the polymer chamber to avoid or reduce the tendency of the molten polymer to cool and cause plugging of the die. Alternatively, the die may, itself, be formed from an insulating material. Webs produced in accordance with the method and die of the present invention display highly desirable properties such as uniformity, softness, opacity, cover and the like.

대표청구항 ▼

In a method of forming a nonwoven web comprising the steps of: (a) providing a molten thermoplastic polymer, (b) spinning said molten polymer through one or more die tip orifices, (c) contacting said spun polymer while hot as it exits said die tip orifice or orifices with a fluid stream to form fila

In a method of forming a nonwoven web comprising the steps of: (a) providing a molten thermoplastic polymer, (b) spinning said molten polymer through one or more die tip orifices, (c) contacting said spun polymer while hot as it exits said die tip orifice or orifices with a fluid stream to form filaments and attenuate said filaments into microfibers having an average diameter in the range of up to about 10 microns, (d) collecting said drawn filaments, and (e) bonding said filaments to form an integrated web, the improvement wherein said fluid stream is provided at about the lowest temperature of available fluid without significant artificial cooling when contacting the polymer, said low temperature fluid stream is insulated from said molten polymer at the die tip, and the forming distance is about 8 inches or less. Apparatus for forming meltblown filaments comprising, (a) means for receiving a molten polymer, (b) a die communicating with said receiving means through a chamber to one or more die tip orifices through which said molten polymer may be spun, (c) fluid supply means adjacent said orifice for directing a fluid at about the lowest temperature of available fluid without artificial cooling against said spun polymer as it exits said die tip orifice or orifices to form filaments and attenuate said filaments into microfibers having an average diameter in the range of up to about 10 microns, (d) insulation between said chamber and said fluid supply means at said die tip, and (e) means for collecting said filaments at a distance of about 8 inches or less from said die tip.