NETTING FOR AQUACULTURE

Abstract

Netting suitable for use in aquaculture which has a half mesh size of 5-100 mm measured in accordance to ISO 1107:2017 and includes cord having a diameter of 0.5-8 mm, wherein the cord includes films of ultra-high molecular weight polyethylene, the films having a width of 0.5-10 mm. It has been found that the use of cord based on films of ultra-high molecular weight PE (UHMWPE) results in nets with improved fouling resistance compared to nets based on conventional ultra-high molecular weight gel-spun monofilament or multifilament yarn. The netting is easier to clean than netting based on conventional ultra-high molecular weight gel-spun monofilament or multifilament yarn. Not only is less frequent cleaning required due to less fouling, the cleaning steps themselves can be carried out at lower water pressure in the high-pressure cleaning apparatus. This results in less damage of the nets during cleaning and lower water consumption.

Claims

1. Netting suitable for use in aquaculture which has a half mesh size of 5-100 mm measured in accordance to ISO 1107:2017 and which comprises cord having a diameter of 0.5-8 mm, wherein the cord comprises films of ultra-high molecular weight polyethylene, the films having a width of 0.5-10 mm.

2. Netting according to claim 1, wherein the netting has a half mesh size in the range of 10-70 mm.

3. Netting according to claim 1, wherein the cord has a diameter of 1-6 mm.

4. Netting according to claim 1, wherein the ultra-high molecular weight polyethylene films have a width of at least 1 mm and at most 8 mm.

5. Netting according to claim 1, wherein the ultra-high molecular weight polyethylene films have a thickness in the range of 10-150 micron.

6. Netting according to claim 1, wherein the number of films in the cord is in the range of 1 to 500.

7. Netting according to claim 1 wherein the ultra-high molecular weight polyethylene films have a 200/100 uniplanar orientation parameter of at least 3.

8. Netting according to claim 1, wherein the ultra-high molecular weight polyethylene films have a polymer solvent content of less than 0.05 wt. %.

9. Netting according to claim 1, wherein the UHMWPE film is substantially free from finish and antifouling composition.

10. Netting according to claim 1, wherein the cord consists for at least 50 wt. % of UHMWPE film.

11. Netting according to claim 1 wherein the film consists for at least 95 wt. % of UHMWPE.

12. Netting according to claim 1 wherein the cord consists for at least 95 wt. % of UHMWPE.

13. Fish pen comprising netting according to claim 1.

14. Method for culturing fish, wherein fish are cultured in a fish pen comprising netting according to claim 1.

Description

EXAMPLE 1

[0043] Netting according to the invention was prepared from cord based on UHMWPE film having a width of 2 mm and a thickness of 60 micron. The film had a polymer solvent content of less than 0.05 wt. %, and a weight average molecular weight in the range of 5-8 10{circumflex over ( )}6 g/mole. The film had a modulus of 180 N/tex and a linear density of 950 dtex. The film is commercially available under the tradename Endumax from Teijin Endumax. Cords were prepared by twisting 10 films together to form a strand, and combining 4 strands to form a cord. The cord had a diameter of 3.0±0.1 mm.

[0044] Comparative netting was prepared from cord based on multifilament UHMWPE yarn SK78-440 dtex, commercially available under the trade name Dyneema from DSM. Cords were prepared by twisting 13 yarns together to form a strand, and combining 4 strands to form a cord. The cord had a diameter of 2.5±0.2 mm.

[0045] Netting with a half mesh size of about 28 mm was prepared from both cords.

[0046] Netting according to the invention and Comparative netting were immersed side by side at three locations with different fouling conditions at three different depths in the North sea (Netherlands territorial waters, subject to tide, netting depth selected such that the netting was submerged at all times). Thus, in total nine samples of each type of netting were tested. The test locations were not accessible to the public.

[0047] The netting was inspected visually for fouling after 2.5 weeks, 7 weeks, and 11 weeks, calculated from the date of immersion. It appeared that at all locations and independent from the immersion time, the netting according to the invention showed less fouling than the comparative netting. Not only was less growth of organisms seem on the netting according to the invention at all locations, the netting was also easier to clean. The netting according to the invention could be cleaned at lower water pressure in the cleaning apparatus than the comparative netting, resulting in a lower water consumption.