Process for making a monofilament-like product
View Patent ↗The invention relates to a process for making a monofilament-like product from a precursor containing at least one strand of fibers made from ultra-high molar mass polyethylene, comprising a) exposing the precursor to a temperature within the melting point range of the polyethylene for a time sufficient to at least partly fuse adjacent fibers and b) simultaneously stretching the precursor, wherein the precursor is mechanically compressed during fusing. The monofilament-like product thus made has a smoother surface appearance, and improved abrasion resistance, for example a reduced tendency to pilling during use as fishing line, than known similar products; making it very suitable for use as fishing line and the like. The invention further relates to a monofilament-like product obtainable by said process, and to semi-finished and end-use products comprising said monofilament-like product.
1. Process for making a monofilament-like product from a precursor containing at least one strand of fibres made from ultra-high molar mass polyethylene, the process comprising:
a) exposing the precursor to a temperature within the melting point range of the polyethylene for a time sufficient to at least partly fuse adjacent fibres, and
b) simultaneously stretching the precursor, wherein
step a) includes mechanically compressing the precursor during fusing by passing the precursor over at least one guiding member having a surface comprising a groove.
2. Process according to claim 1 , wherein the groove is V-shaped.
3. Process according to claim 1 , wherein the precursor is mechanically compressed by passing the precursor over at least 3 guiding members.
4. Process according to claim 1 , which comprises controlling the surface of the guiding member at a temperature within the melting point range of the polyethylene.
5. Process according to claim 1 , wherein the polyethylene is linear and contains less than 1 mol% of comonomers.
6. Process according to claim 1 , wherein the precursor is stretched at a draw ratio of 1.5-10.
7. Process according to claim 1 , wherein the strand comprises twisted and/or air-entangled fibres.
8. Process according to claim 1 , wherein the polyethylene fibres are substantially free from spin finish.
9. Monofilament-like product comprising at least partially fused fibres made from ultra-high molar mass polyethylene obtained by the process according to claim 1 .
10. Monofilament-like product made from UHMWPE fibres, having a titer in the range 5-100 dtex and tenacity of at least 30 cN/dtex.
11. Monofilament-like product from UHMWPE fibres, having a titer of at least 400 dtex and an abrasion resistance of at least 1800 cycles, as determined by a procedure wherein the sample is abraded at room temperature by placing it over a stainless steel eyelet of 1.5 mm diameter at an angle of 90°, which eyelet is submersed in water, and subjecting the sample to oscillating movements at a frequency of 0.5 Hz with a stroke-length of 200 mm, with a constant load of 0.5 kg on the sample, until pilling occurs.
12. Monofilament-like product according to claim 9 , having a sheath-core structure with a substantially non-porous ultra-high molar mass polyethylene sheath.
13. Semi-finished products and end-use products comprising the monofilament-like product according to claim 9 .