| 摘要 |
In order to be able to control the level of orientation and predetermine the tensile failure position of a plastics material mesh structure when in use, as well as to obtain higher stretch ratios and higher production speeds, specially-shaped holes (2) are used when stretching a perforated starting material to form a mesh structure having molecularly-orientated strands. The holes define strand-forming zones (3) which have a centre part (x2) of greater width than end parts (x1); orientation is initiated in the end parts (x1) and travels towards the middle until the whole of the strand-forming zone (3) has been stretched out to form a molecularly-orientated strand. It is found that in the molecularly-orientated strand, there are three portions in which the middle of the strand has moved away from the ends of the strand during stretching the same distance as the edges of the strand, these portions corresponding to the end and centre parts (x1, x2); in between, the middle of the strand has moved away from the respective end during stretching a different distance to the edges of the strand. |
