| 摘要 |
A composite tube of a heat-sealable non-woven material comprises an inner and an outer tube of non-woven, each of said tubes being provided with a longitudinal seal obtained by ultrasonic sealing, the outer and inner tube being fixed with respect to each other by adhesive spots. The inner side of the inner non-woven tube is coated with a membrane for membrane filtration. The seal formed by ultrasonic sealing in the outer tube does not extend to the inner side of the inner tube and preferably the seals in the outer and inner tube are staggered with respect to each other. The composite tube is formed by first forming the inner tube, applying spots of an adhesive upon the outer side of the inner tube, and subsequently applying the outer tube onto the inner tube. During the step of forming the longitudinal seal by ultrasonic sealing in the outer tube it is avoided that the seal as formed extends toward the inner side of the inner tube. |
