Surfaces immersed in the seawater rapidly get covered with marine organisms, called marine biological fouling or often biofouling. Fish nets used for marine aquaculture are well-known for being subject to fouling in a very short time, resulting in lower oxygen levels within the nets and thus, affecting fish growth as well as impeding the dispersal of fish waste from the nets. For this reason, fish nets used for marine aquaculture are often coated with antifouling coatings.

The process of applying an anti-fouling coating to these large nets via the conventional dipping- and drying process is time consuming and expensive as it involves high coating weights relative to the net weight. Further, the coating obtained by that dipping process is often incomplete and uneven and requires long drying times. Also, the coating obtained by said dipping process will be a surface-only-coating, which will erode away faster underwater, so that the antifouling coatings obtained by the dipping process typically last only for about 3-6 months.

In response to this challenge, Lonza, specialized in microbial control solutions, developed a coating formula and process for fishing nets to prevent the proliferation of algae and its negative impact on aquaculture. This innovative coating is based on Zn and/or Cu particles and penetrates the fibres.

Patent # WO2020/225674

The present invention provides a process for treating a marine or submarine textile material to inhibit biofouling thereof, comprising the steps of (a) subjecting said textile material to a negative pressure treatment VAC in a vessel; (b) contacting said textile material with an antifouling formulation comprising micronized particles of one or more biocidal agents, and (c) subsequently, releasing said negative pressure VAC. Step (a) can be performed before step (b), or simultaneously, or step (b) may be performed before step (a).

The invention further provides a marine or submarine textile material with antifouling properties obtained by the process of the invention, as well as the use of an antifouling formulation according to this invention for inhibiting the biofouling of marine and submarine textile materials.

The textile material may be in form of any textile material used for marine or submarine purposes, such as a yarn, rope, net, woven, knitted, or nonwoven fabric, a fish net. The vessel may be any suitable vessel for that purpose, e.g., a stainless-steel pressure cylinder for horizontal loading, or a stainless steel industrial vessel for top-loading, and the like. In the process of the invention, said negative pressure treatment VAC in step (a) comprises applying an initial vacuum Said initial vacuum VAC comprises applying a vacuum of less than 101.325 kPa, preferably of about 85 kPa or less, more preferably of about 50 kPa or less, and most preferably of about 30 kPa, or less. The term “negative pressure” (“VAC”) as used herein refers to a pressure lower than atmospheric pressure, i.e. lower than about 101.325 kPa.

The antifouling formulation used in step (b) comprises micronized particles of one or more biocidal agents, for example copper and zinc based biocides and other commonly used antifouling biocides. In one embodiment, the one or more biocidal agent is selected from copper(l) oxide (CU2O), copper 2-pyridinethiol-1 -oxide (copper pyrithione, CuPT), tralopyril, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), zinc ethylenebisdithiocarbamate, zinc dimethyldithiocarbamate, or zinc diethyldithiocarbamate. In a preferred embodiment, the one or more biocidal agent is selected from the group consisting of copper(l) oxide (CU2O), copper 2-pyridinethiol-1-oxide (copper pyrithione, CuPT), tralopyril, 4,5-dichloro-2-n-octyl-4- isothiazolin-3-one (DCOIT), zinc ethylenebisdithiocarbamate, zinc dimethyldithiocarbamate, and zinc diethyldithiocarbamate. In a more preferred embodiment, the one or more biocidal agent is selected from the group consisting of CU2O and CuPT. In a most preferred embodiment, the biocidal agents are CU2O and CuPT.

[0045]   The micronized particles of said of one or more biocidal agents have a mean particle size of about 0.01 pm to about 25 pm, more preferably of about 0.1 pm to about 10 pm, and most preferably of about 0.3 pm to about 8 pm.

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after 4 months

Advantage of the invention

This is particularly advantageous for commercial, big scale applications. The invention further provides a highly efficient drying process that allows for drying the nets in bundles, and dry nets can be obtained in about 1 hour.

As another advantage, the process provides a drip-free net application of the antifouling formulation, because applying the antifouling formulation via the process of the invention removes most of excess amount of coating solution during a final vacuum step and yields the treated net with significantly less drippage, i.e. in a drip-free condition ready to dry. The process of the invention avoids the 2-3 hours of dripping time required from conventional dip treatment. As a further advantage, the process of the invention allows for treating the nets while still in a bundle (i.e. , without unravelling the net bundle) and being treated in an enclosed vessel, which is considerably less time consuming and less process handling than the dipping process of the prior art.

The process of applying an anti-fouling coating to these large nets via the above conventional dipping- and drying process is time consuming and expensive as it involves high coating weights relative to the net weight.

The inventors have surprisingly found a process for efficiently treating fishing nets with an antifouling formulation that penetrates into the strands of the net material. As such, the antifouling formulation is homogeneously impregnated into the structure of the net rather than merely applied onto the surface or penetrating only partially or inhomogeneously into the nets as with the conventional dipping process. This uniform antifouling coating obtained by the process of the invention will last for a longer period of time than the antifouling coating obtainable by the conventional dipping process. As a further advantage, the process of the invention allows for treating the nets while still in a bundle (i.e. , without unravelling the net bundle) and being treated in an enclosed vessel, which is considerably less time consuming and less process handling than the dipping process of the prior art. It provides workers of less direct contact with the antifouling formulation, which may be toxic.