WO2016093719A1 - Functionalization process for biocide immobilization in polymer matrices - Google Patents

Abstract

The current invention refers to a functionalization process for biocidal compounds with isocyanate reactive function, in order to provide them the ability to be further imobilized through covalent bonds in compatible polymeric matrices. This biocides' imobilization ability allows for its further application as an additive for the preparation of polymeric materials (e. g. : varnishes, paints, etc. ), conferring them antifouling properties by a contact mechanism, thus avoiding the use of conventional processes, which involve the leaching of toxic agents for the biofouling control. The claimed process is therefore an environmentally friendly alternative for biofouling prevention. It consists in the reaction between diisocyanate with biocidal compounds, whose molecular structure includes functional groups compatible with the isocyanate (e. g. : amines, hydroxyl). The modified biocides are then obtained by precipitation, followed by extraction through solvent evaporation under reduced pressure. Depending on the type of biocide used and purity, the optimized reaction conditions allow for the achievement of conversions as high as 95 ± 5%.

Description

DESCRIPTION

Functionalization. process for biocide immobilisation in polymer matrices

Field of the invention

Technical field of the invention

The current invention refers to a process for the immobilization of bioactive or antifouling agents (biocides) in polymeric matrices, through the functionalization of biocides with isocyanate reactive function. Following this new approach, this process is able to provide antifouling polymeric systems for the biofouling control, avoiding the releasing of toxic agents (leaching) into the environment. In particular, it can cover a broad range of applications in aqueous medium, since it is guaranteed the compatibility between the polymeric systems and the isocyanate functionality of the biocides or bioactive modified agents, as well as, assured that the original structure of the biocides remains intact after its functionalization.

State of the art

Water is the survival key of all living organisms. It is a crucial resource for the growth and sustainability of the humanity, both at a commercial level, and for its own survival. But ironically, what should be a benefit also becomes a major cause of problems. A spontaneous colonization by aquatic organisms occurs on surfaces in contact with water (marine or freshwater environment) or on submerged surfaces. This natural phenomenon, known as biofouling, is a major problem in the management of water systems in various industrial activities {industrial biofouling) . For example, for marine infrastructures, such as: commercial or sightseeing boats, oil platforms, docks, cages/nets or vessels for aquaculture, desalination processes; for freshwater systems, such as purification processes, water treatment and distribution (pipes, membranes); or even for surgical materials (1, 2), The impact of biofouling in those systems is of increasing concern, it is associated with economic and environmental penalties, and can even pose serious risks to the human health. The shipping industry constitutes a good example of the huge impact of this natural phenomenon. The marine biofouling, i.e., the accumulation and growth of marine organisms on ships' hulls leads to significant increases on its surface roughness. Particularly when macrofouling is involved, that includes the attachment/growth of organisms such as: mollusks (soft macrofouling), seaweeds, corals, sponges and marine crustaceans such as mussels (hard fouling) . The roughness increase provided by heavily attached biofouling, mainly hard fouling can lead to drag friction increases up to 40% (3), and subsequently generating powering penalties as high as 86% at cruising speed (4) . These data show that more energy is required to maintain the same speed of vessels movement, thus promoting higher power consumption (fuel) . Studies on the roughness effect, had showed that an average increase of 10 μm in hulls 'roughness can lead to a fuel consumption increase between 0.3 - 1.0% (5). Therefore, the consequences of this bio attack on surfaces are indeed an urgent concern, moreover, if it is consider that fuel consumption can contribute with 50% of the ships operational costs (63. On the other hand, this power consumption increasing also leads to gas pollutants emissions increases into the atmosphere (e.g.: nitrogen oxides - NOx, sulfur oxides - SOx, carbon monoxide - CO, carbon dioxide - CO2, volatile organic compounds - VOCs, etc.). The International Maritime Organization (IMO) estimated that under extreme scenarios, gas emissions due to increased fuel consumption by the world's shipping fleet could lead to a- maximum annual growth in CO2 emissions up to 5.1%, which would correspond to more than the double by 2030 (7) . In addition, biofouling on ships is also associated with the introduction of invasive species in different oceans exploited by the maritime fleet, causing adverse side effects on the different aquatic ecosystems.

In other industrial activities, the impact of biofouling is also quite significant. For instance, its accumulation in treatment circuits, purification and/or distribution of water, which leads in a short term, to the clogging of pipes and/or other units inherent to the process (membranes, heat exchangers, cooling columns, etc.). This accumulation/obstruction increases the circuits loading, and if not removed will substantially reduce the efficiency of the systems, as well as promote the further contamination of the aqueous fluid through the entraining of microorganisms (bacteria, fungi, etc.).

Nonetheless, for the aforementioned industrial activities, and for any other stationary or non-stationary system involving an aqueous medium, the biofouling attach is also associated to the deterioration of the contaminated substrates, as a result of blocorrosion effect. For example, in cooling circuits of cogeneration plants systems, biofouling can be responsible for efficiency losses of about 5%, and substrates deterioration by corrosion of about 20% (1).

Due to economic and environmental impact of biofouling, it is clear the urgency on its control and/or prevention. In the last decade there has been a growing concern towards finding solutions and/or strategies to mitigate this biological "attack"- Several studies have been developed and/or new technologies implemented (2, 3, 8), Among the available conventional strategies, the one considered the most effective is based on a chemical control (1). This chemical based strategy includes antifouling processes that act through a direct and/or controlled releasing of toxic chemical compounds, usually known as blocides (e.g.: chlorine dioxide, hydrogen peroxide, quaternary ammonium based compounds, other organic and inorganic metallic compounds), into the immediate surroundings of the contaminated surface. This strategy is commercially well established in the treatment and/or purification of water networks/circuits, as well as in the marine industry where such agents are applied as additives in antifouling paints, which act as protective coating through leaching mechanisms (1) . However, and despite its recognized effectiveness, this strategy has revealed significant limitations and/or drawbacks, in particular: i. It requires, as a direct application, an effective mass transfer between the aqueous medium and the contaminated surface. This can cause a large consumption of the used antifouling agents; ii. On the other hand, and considering the condition mentioned in the above item, i.e., the treatment of a contaminated surface, implies the presence of multiple attached organisms, which resulted from the developed colonies, in addition to the initial biofilm (9, 10) . Since any toxic agent dissolved or dispersed in the aqueous medium will only act on the outer bio-layer, the provided treatment will not be totally effective without additional physical cleaning of the contaminated surface, thus meaning the need of an operational system interruption/ iii. The continuous releasing of antifouling agents into the aqueous medium, which commonly exhibit the toxicity not restricted to the target organisms, has revealed significant harmful consequences in the ecosystems. The release of those toxic agents also conducts to their accumulation in the aquatic environment, which can also cause the appearance of compounds with a higher toxicity, as a result of their degradation; iv. The effectiveness of this strategy is still limited due to the diversity of species and conditions in different aquatic environments. The action of the antifouling agents is restricted to specific organism ranges, which does not always fit all scenarios. Therefore, the reinforcing with other toxic agents is required, thus worsening the impact for both economic and environmental levels. The drawbacks and the impact in the environment of this chemical control strategy have been leading to a reduced acceptation by the international community. Reason why strict legislation has been implemented, in particular the European Biocidal Products Regulatory <BPR - EU Regulation No. S23/2012, 22 May 2012) that regulates, among others, all products possessing biocidal and/or antifouling properties. This European regulation is regularly reviewed. The lasted revision entered into force in 2013 (11) . This lasted update has substantially reduced the list of allowed biocides or antifouling agents and more restrictions are expected in a near future. Therefore, it is urgent to provide new alternatives to control or combat biofouling on surfaces in aquatic environments, with strategies that enable to find a balance between effectiveness in biofouling eradication, in order to contribute to the sustainability of the industrial systems, and at same time offering an environmentally friendly alternative. The meeting of this balance is a current scientific and technological challenge.

The development of alternative antifouiing solutions is increasing, particularly for polymeric antifouling coatings such as antifouling paints. Its simplicity, versatility, efficiency and ability to be tailored to several types of substrates, have been the reason for their choice. However, and after the severe restriction of toxic antifouling products leaching (International Maritime Organization - IMO, 2008), mainly due to its inherent ecotoxicity towards the aquatic ecosystems, such as antifouling marine paints containing organotin compounds, in particular tributyitin (TBT) (12-14), which led to the emerging of a new generation of polymeric coatings, focused on non-toxic strategies (3, 15). Mot aiming to include an exhaustive description of all those strategies, it is only provided a brief description of the main exploited and/or commercialized strategies, which are further compared with the claimed alternative process. Detailed descriptions of such alternatives can be found in review papers in the field (8, 10) . Briefly, non-toxic emergent strategies can be grouped into two main groups :

2. Non-biocidal coatings a) Non-stick polymeric coatings (e.g.: foul-releasing coatings - FRCs), whose technology was developed and used particularly for the shipping industry through antifouling protective coatings. To date, and as an environmentally friendly technology, this alternative is considered the most promising one. In this classification the most effective coatings are composed by silicone based polymers or fluoropolymers, mainly due to their intrinsic smoothness properties, providing coatings with a low surface energy which lead to minimal adhesive smooth surfaces (non-stick properties) .

Dimethylpoiysiloxane (FDMSe) based coatings have been the most explored (10}, due to their nonpolar properties and low surface energy (Nm ~ 22 m^-1) . However, this class of non-stick coatings revealed some disadvantages which limit their further application. They are usually more expensive and mechanically fragile, reducing its lifecycle and/or requiring a frequent maintenance, thus becoming an expensive alternative. Moreover, their hydrophobic properties make them vulnerable to microfouling, i.e., the adhesion of microorganisms which form the biofilm (e.g.: diatoms), limiting their further application in non-stationary conditions (e.g.: limited to be applied on fast moving vessels, up to 15 knots) . In order to improve their non-stick performance, oils have been included as additives in their formulations. However, its use is controversial, since their composition is not fully known, as well as their continuous releasing long-term effects in the aquatic environment (16) . b) Biomimetic surfaces: this biomimetic strategy is based on the replication of texture and topography of existing natural mechanisms against biofouling. For instance, it is the case of shark skin or crustaceans organisms (e.g.: crab). Recent studies, which involve methods such as laser ablation, photolithography, or mold and casting, have been the most explored to confer microtopography on polymeric substrates (e.g. Poly(dimethyipolysiloxane) (PDMS), poly (vinyichloride) (PVC) or polycarbonate) flOJ_* So far, the results achieved from this strategy are promising (2, 17), but are still in an early stage of development and/or even at a pilot scale (e.g. Sharkiet technology AF™, (3)). Moreover, in spite of not fully understood most of the natural defense mechanisms against biofouling combine different antifouling mechanisms, for instance acting through a joint action of physical and chemical mechanisms. This reveals that this biomimetic strategy may not be by itself fully effective, unless combined with another strategy.

2. Biocidal coatings

Siocidal coatings are those that act by the action of biocidai agents incorporated in the coating formulations. Two main routes of action, resulting from two distinct strategies, for the inclusion of those agents in the formulations can be considered: a) Bioactivity by leaching or a controlled release of the bioactive agent. In this strategy all the processes able to include harmless bioactive agents to aquatic biota in the formulation of the coatings, allowing its further leaching in a controlled way are included. Nowadays, and mainly for marine applications, biodegradable biocides and/or biocides exhibiting a lower ecotoxicity in insoluble or soluble polymeric coatings matrices are applied following this strategy (ablative systems, Controlled Depletion Polymer Coatings - CDPs) and Self- Polishing Coatings - SPC) . However in these systems, it still exist a continuous releasing of biocidal agents and/or products resulting from agents biodegradation, which' s for the majority is still unknown its long-term action. On the other hand, their action is also limited to certain target species, reason why its action is usually improved through the combination with other biocides, that can by themselves be more aggressive to the environment. For example, the ablative antifouling paint provided by International Interlux, using the BIOLOX technology, operates through a combined action of a biodegradable recent approved biocide, ECGNEA (PESTANAL) with copper oxides. Alternatively, the replacement of synthetic biocides by natural based antifouling agents (natural antifoulants - NPA's) (18-20) has gained prominence. Among the extracted agents from marine natural sources, the most promising have been the furanones (21) and Capsaicin (the active component of pepper) from land-based sources (22).

Enzymatic antifoulants have also been an emergent alternative, included in this strategy based on natural sources (21, 22). Despite the advantages associated with the application of natural based antifouling agents, its implementation at an industrial scale is still in an embrionary stage. Essentially technical limitations need to be overcome, in order to become it an industrial sustainable alternative. For instance, the costs associated with synthesis and/or extraction processes of organic compounds, are generally complex and expensive. On the other hand, the immobilization in a polymeric matrix is still in a development phase, i.e., at a lab scale. However, there are few exceptions, such as the DCOIT (4,5-dichioro-2-N-octyl-4- isothiazolin-3-one) (20), an active ingredient of Sea-NineTM antifoulant, provided by Dow Chemicals. In these Sea-Nine systems the natural based biocide is protected by microencapsulation, allowing their later inclusion in polymeric systems without suffering damages, and its controlled leaching into the polymeric film surroundings, which protects the submerged surface in the aqueous medium. Nevertheless, and despite being an emerging alternative, mainly regarding the controlled leaching of the agent, it is only effective when applied in combination with other antifouling agents such as copper oxide. Thus, revealing that its range of action is still limited. Moreover, it is clear that the continued release of the antifouling agent into the surrounding environment, limits its life cycle. b) Bioactivity by contact

The chemical immobilization, i.e., the fixation through chemical bonds of antifouling agents in a polymeric matrix, has been another emergent and environmentally friendly strategy for biofouling control, with increasing acceptance by the scientific and industrial community (17, 24, 25J, mainly due to its environmental harmless, as a result of their action by contact, that avoids any leaching of the used toxic agents.

This strategy has been followed for the immobilization of many promising bioactive compounds. A. Kugel and co-authors (24} have reviewed in their paper the main developed techniques for the immobilization of anti-fouling agents in polymeric matrices. Among them the immobilization of compounds based on ammonium and/or quaternary ammonium salts stands out, due to their high bacteria fouling resistance. They use in particular, grafting techniques for those agents immobilization in the polymeric matrix. However, many of these techniques still evidence leaching of. the toxic agents (26) , and/or are only suitable to polymeric matrices with specific properties (thermoplastic, thermosetting) .

Another alternative technique is the use of polymers which possess by themselves biocidal properties. The most prominent has been the polyethylene glycol (PEG) (18/ 27), mainly for their particular ability to inhibit the adsorption of proteinaceous material. Nonetheless, systems with PEG function easily degrade by oxidation, which can compromise their resistance at real conditions.

Despite this strategy of biocidal agents immobilization is a potential alternative, it still exhibits technical limitations, particularly its compatibility with the existent large variety of polymeric systems, and limit range of biocidal action, since many compounds are only bioactive for specific species ranges. In addition, and despite of the several performed efforts for the immobilization of bioactive agents in polymers, to date any method and/or process is not sufficiently versatile, efficient and environmentally friendly, thus, does not convince the scientific and industrial community, and new alternatives are sought .

The claimed process of the present invention is specifically intended to introduce a new process for the immobilization of ancifouling agents, through their functionalizacion with isocyanate reactive function, which makes them able to be fixed in several polymeric systems ie.g. polyurethane and silicone based), thus become them versatile to different applications. This innovation also allows the immobilization of different biocides in a same polymer matrix, extending its range of action and ability to be adapted to different conditions and promoters of biofouling, therefore, supporting synergistic actions of the applied biocidal agents.

As an implementation and way of distinguish the main advantages and benefits that this new process can offer, it is provided a comparison of it with recent patented technologies in the area, which may be referred as potentially strategies closed to the claimed one. This is the case of polymeric materials possessing antifouling activity claimed in US 7544722 82 and OS 8,053,5.35 B2, and which involve the functionalization of triclosan biocide with aerylate function, able to be incorporated in copolymers chains (with a main carbon and/or silicone based framework)_. Despite the similarity of the above claimed antifouling polymeric materials with the current claimed invention, in fact they apply different raw materials to also provide a distinct reactive function for further biocide immobilization. This implies a completely different functionalization process. Furthermore, they claim the final polymeric material, while in the present case it is intended to claim the functionaiized biocides, characterized as bioactive components to be applied in polymeric formulations, thus presenting themselves as a more versatile alternative.

A. Kugel and co-authors (24) carried out an exhaustive review of the main techniques and/or processes for the immobilization of biocides in polymeric coatings. Although the several mentioned strategies may suggest some similarity, regarding the fact that involve the immobilization of antimicrobial compounds and/or biocide by chemical bonds, for example the antimicrobial thermoplastic coatings, in fact many of the followed strategies continue to demonstrate leaching of those bioactive compounds, or mostly rely on the immobilization of quaternary ammonium based biocides and/or on the preparation/development of polymers possessing by themselves biocidai properties. None of the above described processes refers to the functionalization of biocides with isocyanate reactive function.

To be more precise, for instance the processes described by A. Kugel and co-workers (24 J (WO 2013/036996 Al) suggest the immobilization of biocidal agents with quaternary ammonium function in compatible polymers with carboxyl reactive function- However, and despite the suggested immobilization, the produced polymer is partially soluble in water, thereby, and when in contact with an aqueous medium, it leads to the leaching of the bioactive agent, thus not following a non-toxic and/or environmental friendly strategy.

Many other examples can be found in published materials and/or patents, but most of them involve the development of processes able to offer a more controllable releasing of biocides into the vicinity of the contaminated surfaces, than to the immobilization/fixation of biocides in polymeric matrices. A representative example is the technology proposed in the application EP N° 0679333 A2 (1995). The proposed technology proved to be innovative by reducing adverse effects inherent to the presence of 3-isothiazolone based biocides in polymeric systems for the control of mildew and/or biofouling (e.g. marine and/or decorative paint formulations, etc.). It involves the immobilization of the biocidal agent, through their encapsulation in polyurea based capsules. The encapsulation of the biocide is accomplished by the polymerization reaction (interfaciai condensation) between polyisocyanates (organic phase), and an aqueous phase consisted of several ingredients, including among them a polyamine based crosslinker. The biocide is added to the organic phase before mixing it with the aqueous phase. During the polymerization reaction, occurs the formation of capsules retaining simultaneously the biocide in their core. The obtained capsules are then extracted becoming able to be added as an additive in polymeric systems, by using conventional dispersion methods. Even though this technology involves a prior immobilization of the biocide, its performance relies however in a process of leaching and/or releasing of the biocide when applied. In fact, the encapsulation is a technology whose primary application aims to control the rate of releasing of active ingredients contained in the capsules ⁽permeable), thus does not involve an effective immobilization of biocide and/or biocide with isocyanate reactive function in polymeric matrices, by a chemical bind strategy. Therefore, it not only does not act by contact, as well as does not provide a compound with isocyanate functionality with biocidal properties, which is far from what is claimed in the present invention.

Another example, relatively recent, is described in patent application EP 2170044 Bi (2014). In this application, it is claimed a polymer composite with biocidal functionality, involving in practice, a biocide incorporation in a polymeric matrix through a combination of binders and/or polyacrylate- based crosslinking agents and gelatin with superabsorbent properties. Once again, the performance of the final obtained polymer containing the biocide follows an action mechanism by leaching, which occurs by diffusion and/or osmosis of the biocide initially trapped in the polymeric structure. In addition, preliminary studies by E.B. Silva and co-workers (28) highlighting potential biocides able to be immobilized via chemical covalent bonds. In particular, the studies demonstrated the immobilization of the isocyanate functionalized Irgarol. biocide with a poiyol compound. But efforts are still needed to ensure its effective immobilization, as well as prove its antifouling efficiency in polymeric systems, such- as antifouling paints_* The polymeric systems are complex by themselves, involving multiple components and addictves which can lead to several side reactions and incompatibilities when an additional component is included in their composition. This complexity requires a redesign of all the previously considered assumptions, that only evidenced the ability of immobilization, and which do not always guarantee their subsequent efficiency and performance by contact (i.e. without leaching) . This is also true for other examples mentioned above (A. Kugel and co-workers (24)), where even if an immobilization method (grafting; is applied in order to promote the fixation of the biocide in the polymeric matrix, it can be not enough to prevent its subsequent leaching.

Briefly, the process claimed in the present invention aims to provide especially and relatively to the available technologies:

• The ability to confer isocyanate reactive functionality into biocides, allowing its subsequent immobilization in a wide range of compatible polymeric systems (e.g. polyurethanes and silicones based) representing thereby a non-toxic and/or environmentally friendly antifouling alternative;

· High conversions of biocides functionalization up to 95%, depending on the purity of the used raw materials;

• The isocyanate function, recognized for its high reactivity, ensures the success of its immobilization in the polymeric system, after purification/extraction of the functionalized biocide.

• Biocides with reactive isocyanate function are likely to be included as additive in polymeric systems using conventional dispersion techniques?

• Compatibility on the immobilization of different biocides, with isocyanate reactive functions, in a same polymeric system, in order to widening the antifouling range of action of the obtained polymeric product, and therefore, providing potential synergistic effects. • The immobilization ability of the isocyanate functional biocides, as well as its compatibility with a diversity of polymer systems, makes them able to be applied in many applications_/ particularly as ingredients in paint formulations, varnishes and/or in the composition of polymeric based materials. In these strands, they can be applied in antifouling products used for the protection of: ships" hulls, marine structures (aquaculture, platforms, etc.), pipelines in contact with water (freshwater or seawater) , filters, packages_/ hospital materials, etc.

Susmtary of the invention The present invention relates to a functicnalizatior. process of biocides with isocyanate (NCC) reactive function, conferring them the ability of immobilization by covalent bonds within compatible polymeric matrices.

The process is composed of four basic stages: i. Biocide dissolution in a pure and proper dehumidified solvent; li.

Functionalization reaction between a diisocyanate and the solution containing the biocide composed of compatible functional groups; iii. A precipitation step that can occur spontaneously after the reaction of functionalization step, or it can be promoted by distillation at the end of the reaction; iv. Drying of the obtained precipitate product by solvent evaporation under reduced pressure conditions. The process allows to obtain functional biocides, with conversions as high as 95 ± 5%, depending on the purity of the raw materials. Its ability of immobilization and compatibility for a diversity of polymeric systems, allows for its application as an additive or component in polymeric based formulations, providing them with antifouling properties by contact, i.e., without the releasing of any toxic agent into the surroundings. Therefore, it is an environmental and economical attractive alternative when compared with the existent conventional antifouling solutions in the market for biofouling control, mostly based on a mechanism of leaching of toxic agents. On the other hand, it allows the immobilization of several functional biocides in a same polymeric matrix, thus widening its antifouling action spectrum, making it suitable for different ecosystems, and therefore different biofouling promoters' conditions. It is, for instance, suitable to be used in products for the protection or preparation of surfaces in contact with water or aqueous medium, such as: medical materials, marine structures or water distribution pipelines, food materials, etc.

Detailed description of the invention

The previous described available solutions for biofouling control, clearly evidence their incompatibility with an environmental friendly strategy, as a result of the continuous releasing of toxic agents into the aquatic medium. On the other hand, the existence of technical limitations on potential alternatives is still hampering the full development of nontoxic and more efficient solutions, as well as the acceptance of those alternatives by the scientific and industrial community. The present invention aims to overcome those limitations by providing an innovative process for the functional!zation of biocidai agents and/or compounds, possessing antifouling properties, with diisocyanates. Such process will provide the antifouling agents with isocyanate reactive functionality, the ability to be immobilized through covalent bonds in a wide range of polymeric systems (e.g. polyurethanes, silicones, silicone- urethane copolymers, · polyvinyl alcohols, polyesters, polycarbonates and mixtures thereof, etc.), particularly in amine and/or hydroxy1 functional systems_* Thus, the reactive isocyanate functional biocides with ability to be chemically immobilized in polymeric systems, avoid their further leaching or releasing into the environment, ng a non-toxic alternative for the biofouling control.

The term "biofouling" according to the present invention, should be understood as the colonization by aquatic organisms, coming from marine environments, freshwater or other aqueous medium, on totally or partially immersed structural surfaces, or in contact with the aqueous medium. The present invention particularly illustrates examples of marine biofouling ⁽Figure 1), which can involve the attachment or fouling, depending on the stage of development (29), with species of organisms such as: bacteria (single cell), macroalgae spores (multicellular), molluscs, crustaceans, etc. The term "structural surfaces" in aquatic environment, and according to the present invention, should be understood as stationary and non-stationary structures in contact with an aqueous medium, for example: aquaculture nets and cages, ships, pipelines in aqueous circuits, pools, filters, surgical materials, etc. The type of material used in those structures is not a critical aspect of the invention, since those structures acts as a support for the polymeric material with ant1fouling properties, provided by the immobilization of a single or multiple biocides in the polymeric matrix.

Accordingly to the claimed functionali2ation process, compatible biocides are those which follow the criteria: possess in their molecular structure at least one reactive or compatible function with the isocyanate group, for example amines, hydroxy1, carboxyl, etc.; act preferably by contact for biofouling inhibition; and are chemically stable. Alternatively, it is also possible to perform a prior biocide modification in order to provide the required compatibility. In addition, and as an inventive process, it is not limited to biocides that can act by contact. Immobilization of biocidai agents that act by other mechanisms can also prove to be feasible, since the bioactive group or biocide bioactive function relies free, i.e., does not constitute the molecular structural function used for the covalent immobilization_*

The selection of the biocide or bioactive agent must also be in accordance with the list of substances allowed by the international regulations, including the European Directive which regulates the Biocidai Products (BPR - EU Regulation No. 528/2012, 22 May 2012) .

The term "biocide", according to the present invention should be understood as any chemical bioactive compound or substance, i.e. able to inhibit and/or kill fouling organisms. This can include a wide range of biocidai agents, which can be classified as bactericides, pesticides, fungicides, and algaecides, among others, used in several industrial areas.

The biccides used as example and for the claimed functionaligation process in the present invention, are commercial biocides with proved efficacy, such as: 4-Bromo-2- M- chlorophenyl)-5~(trifluoromethyl)-lH-pyrrole-3-carbonitriie (CAS 122454-29-9) and 2- (tert-Butylamlno) -4- (cyclopropylamino) -6- (methylthio)-s-triazine (CAS N^o: 23159-98-0) . The term "biocide with reactive function", according to the present invention shall be understood as any bioactive chemical compound or substance possessing a reactive functional group, compatible with the isocyanate function_* It can for instance include biocides possessing in their structure amine and/or hydroxy1 functional groups.

The term "functional biocide" or "biocide with reactive isocyanate function", according to the present invention shall be understood as any bioactive chemical compound or substance, possessing at least one isocyanate group in its chemical structure.

The functional biocides obtained by the claimed process can be applied in a wide range of applications In aqueous medium, being included in formulations (e.g. paints, varnish) as an ingredient or additive, or a component in the composition of polymeric based material (ropes, nets, or natural based polymeric materials), resulting in environmental friendly products with antifouling properties, potentially competitive and with significant impact on large and technological important market segments, such as: marine paints, protective coatings and/or polymeric materials for submerged structure protection on rivers, ports, water treatment circuits, oceans (offshore culture), offshore platforms and hospital materials and equipment. It can also include other market segments of significant dimension such as packaging.

The versatility and compatibility of functional biocides can cover several sectors from food, health, polymers industry, marine, aquaculture, to the distribution and treatment of water_*

In addition to such versatility, the compatibility and the high isocyanate function reactivity which characterizes the functionalized biocides, ensures the success of the immobilization by applying conventional dispersion processes and providing formulations/polymer systems optimizations well known among the experts in the field or in the suitable industrial sector. The process claimed in the present invention, involves in a first step the dissolution of - the selected biocide with a pure and appropriate dehumidified solvent. The selection of the organic solvent should be carefully performed in order to ensure a high solubility, stability and low moisture in the system (non-hygroscopic) . Monpolar and aprotic solvents, which allow achieving mass solute concentrations between 1C~5Q %, are preferred.

It should be also guaranteed the absence of humidity or water in the used raw materials and therefore, a prior drying step should be included, using in particular to organic solvents a prior distillation process or the use of molecular sieves. Solvent moisture control can be provided by using Karl Fisher analysis, using for instance aportable Karl Fischer Moisture Meter equipment, Model CA-21 front Mitsubishi.

After the dissolution of the biocide is guaranteed, its functionalization is carried out, through its reaction with a diisocyanate under an inert system (under nitrogen) . The selection of the diisocyanate reactant relies preferably on monomers/isomers with high purity and stable under the reaction of functionalization conditions. The reaction time, the diisocyanate content and the temperature of the reaction should be adjusted depending on the type of biocide, diisocyanate reactant, the stoichiometry of the reaction, and the desired or required degree of functionalization.

The reaction should proceed slowly, promoting the slow addition of the biocide solution to the diisocyanate. The reaction product, the functionslized biocide, will be obtained by spontaneous precipitation during the reaction. If this does not occur during the reaction, the precipitation can be promoted close to the reaction terminus by a reaction process with an in situ solvent distillation, promoted by a gradually increase of the reaction temperature to the boiling temperature of the solvent. It should be mentioned that the purpose of this distillation step is only to induce the precipitation, and thus, it should be stopped after ensuring the setting of the product precipitation, followed by the further extension of the reaction until complete precipitation. This process is only feasible if the solvent boiling temperature does not promote side reactions and/or modifications of the involved reactants.

Finally, and for the purification of the reaction precipitate, i.e., the obtained functionslized biocide, the solvent evaporation under reduced pressure is carried out. Then a solvent washing step and a new precipitate drying by evaporation under reduced pressure are carried out_* The obtained biocide with reactive isocyanate function can be applied in its solid state in compatible polymeric formulations. Alternatively, it can be used as dispersion or as a concentrated solution, prepared by using compatible solvents. It is preferable its application as a solution in order to ensure an effective dispersion in any polymeric system, as well as, to promote a long-term stability if longer storage is required.

Its application does not require any special procedure. Conventional dispersion processes for the preparation of polymeric formulations known in the field are suitable. It is however recommended, its application at mass contents ranging from 2 to 10 %, and preferably between 4 and 6 %. Nonetheless, this content range depends on the applied biocide type and its action/efficacy for the target organisms.

The isocyanate reactive function also offers versatile biccides, that are able to be immobilized as a mixture of biocides, i.e., it allows a joint immobilisation of different biocides in a same polymeric matrix. This ability favors the widening of its range of action and suitability for different conditions, through the achievement of potential synergistic effects.

Specifically, the present invention relates to a biocide functionalization process with reactive isocyanate function, providing on those biocides the ability of immobilization by covaient bonds in matrices and/or in compatible polymeric based formulations, such as silicones and polyurethanes. These functionalized biocides provide biocidai properties into the materials where they are immobilized. The process is characterized by the following steps:

Biocide dissolution in a pure and proper dehumidified solvent ;

Reaction of functionalization between the solution containing the biocide and a diisocyanate, under an inert medium at atmospheric pressure, 1 bar;

Formation and precipitation of the reaction product (mainly functionslized biocide). This step can occur spontaneously during the reaction, or after cooling, or can also be induced at the end of the reaction by in situ solvent distillation; (d) Decantation and drying of the precipitate by solvent evaporation under reduced pressure;

(e) Purification of the precipitate by washing with a suitable solvent, followed by a new drying process, step (d>;

And, optionally, (f) Dispersion or dissolution of the functionalized biocide in a pure and dehumidified suitable solvent, favoring its subsequent dispersion in polymeric based formulations, as well as, the biocide stabilization with reactive isocyanate function for later medium/long-term storage.

In step (a) non-hygroscopic solvents, nonpolar and aprotic whose solubility of the biocide allows obtaining concentrations between 10-50% and preferably between 15-30% are preferably used_* Solvents with these properties are, for example, butyl acetate, ethyl acetate, hezane, methyl~pyrrolidone or cyclohexanone, among others.

The reaction of functionalization (step (b) ) is carried out with a temperature between 40 and 90 °C, and a stirring speed between 350 and 500 rpm. In step (b) the reaction occurs with molar ratios of the isocyanate function from the diisocyanate and the compatible functional group from the biocide, between 1:0.5 and 1:1, and preferably between 1:0.8 and 1:1. The reaction of functionalization proceeds for periods of time between 7 to 11 hours.

It is recommended the use of pure diisocyanates reactants (monomers/isomers) with isocyanate mass contents between 2.5 and 35 %.

In step (c), and at the time of the in situ distillation, the reaction temperature should be gradually increased in the last hour of the reaction at a heating rate between 1 to 3 °C/min. The maximum reaction temperature Is preferably comprised between 80-90 °C. The amount of distilled solvent should not exceed 1/2 of the volume of solvent used in the reaction.

In step (d) the time and pressure of the evaporation process should be adjusted in accordance with the type and amount of the used solvent.

The claimed functionalization process allows obtaining conversions as high as 95 ± 5%, depending on the purity of the used raw materials. Description of the figures

Figure 1 illustrates the marine biofouling on specimens coated with antifouling polyurethane based paints, after 1 month of immersion in Portuguese seawater (Peniche), containing mass contents of the inufccbilized biocides (EM-NCO wt.%/IM-NCO wt.%) of: 5/5 (specimen X); 2.4/2.4 (specimen 2); 3.3/6.7 (specimen 3); 6.7/3.4 (specimen A); 7,6/2.5 (specimen S); 3.5/2.4 (specimen 6); 5,9/3_*9 (specimen 7); 4,2/6.3 (specimen 8); 2 wt.% Zinc pyrithione in the specimen 9; and a specimen coated with a commercial antifouling paint (Olympic ÷) . Since EM ^» 4-brom©-2- <4-chlorophenyi) -5- (trifluoromethyl) ~XH~pyrrole-3- carbonitrile and IM » 2- itert-Butylamino) -4- (cyclopropyiamino) ~ 6- (methylthio) -s-triazine. EM-HCO corresponds to the EM biocide with reactive isocyanate function and IM-NCO corresponds to IM biocide with reactive isocyanate function.

Figure 2 illustrates the marine biofouling on specimens coated with antifouling polyurethane based paints, after 3.5 months of immersion in Portuguese seawater (Peniche), containing ratios of immobilized biocides (EM-NCC/NCO-IM) of 0 (reference sample); C.5 (sample 3); and 1.5 (sample 7). EM and IM correspond to the same biocides mentioned in Figure .1. Figure 3 shows in detail the not physical attached biofilm on the surface of antifouling paints containing immobilized biocides with ratios (EM-NCO/NCO-IM) of I (specimen 1) after 3.5 months of immersion in Portuguese seawater (Peniche) . EM and IM correspond to the same biocides mentioned in Figure .1.

Figure 4 illustrates the marine biofouling on specimens- coated with antifouling silicone based paints, after 2.5 months of immersion in Portuguese seawater (Peniche), containing immobilized biocides with total contents of: 2.57% EM-NCO in specimen 2; 2.53% of the mixture EM-NCO + IM-NCO in the specimen 6, with contents of each biocide of 1 . 02% and 1 , 51%, respectively; and 0% In the control, this is, coated specimen without any biocide. EM and IM correspond to the same biocides mentioned in Figure 1.

EXAMPLE 1

This first example intends to illustrate the functionalization of the biocide (4-bromo-2-(4-chlorophenyl> -5- (trifluoromethyi) - 1H-pyrroie-3-carbonitrile (CAS: 122454-29-9)), named in this invention by EM, and which possess a reactive amine function (NK), compatible with the isocyanate (NCO) function.

In a first step the dissolution of the biocide in the previously dried ethyl acetate (99.5%, Sigma-Aidrich) is carried out, in order to obtain a solute content of 20% . The solution is then placed in a separatory funnel.

In a 3-necked flask the selected diisocyanate is placed. For this functionalization reaction a pure methylene diphenyl diisocyanate (MDI) was used pure, in particular the 4 , 4-MDI isomer. This diisocyanate is characterized by a molecular weight of 250.25 g/mol, a density of 1.230 g/cm~ and an isocyanate content (NCO) of 33. 4 ± 0. 1% . The flask is then heated and kept at a temperature of 45°C. The amount of the used MDI was determined in order to guarantee a molar ratio NCO (MDI)/NH (biocide) = 1 .05.

In a second step the system is assembled, by attaching a mechanical stirring system, and a separatory funnel containing the biocidal solution, as well as an in situ distillation system. The entire system is then placed under an inert medium (under nitrogen) . After stabilization (inert medium and stable temperature) , the biocidal solution is added dropwise into the diisocyanate for 9 hours, under a continuous stirring rate of 385 rpm.

After 9 hours of reaction, and completed the addition of the biocide solution, the step of the solvent distillation begins in order to induce the precipitation of the functionalized biocide. This step is accomplished by a gradual increase of the reaction temperature at a rate of 1 °C/min until reaching a temperature of 83^CC, and guaranteeing that the distilled solvent does not exceed 1/2 of the total volume of the used solvent. Subsequently, the heating is ceased and the reaction mixture is left to cool till room temperature, maintaining the stirring, after which the functionalized biocide is collected by filtration, under inert medium.

The obtained precipitate is then subjected to a drying process by solvent evaporation in a rotary evaporator at 55°C, and providing a gradual pressure reduction ranging from 193 mbar to 0 mbar. After the first drying, a washing step is followed with the suitable solvent and a further drying of the washed precipitate by evaporation under reduced pressure.

The isocyanate (NCO) mass content of the obtained functionalized biocide, named herein by BM-HCC and determined by an adopted standard method in ASTM D2572, was 10 s 1%. The EM-NCO was further analyzed in order to prove its functionalization with the reactive NCO function, as well as, to identify its location in the biocide molecule structure. Two techniques were used:

(a) Infrared Fourier transform Spectroscopy (FT.!?.), using a Nicolet Magna FTIR 550 spectrophotometer, and where analyses were performed on samples supported in potassium bromide (KBr) discs in a frequency range between 400 and 4000 cm^-1. Attenuated total reflectance (ATR-FTIR)could also be used for the purpose;

<b) Nuclear magnetic resonance (NMR) using a Bruker Avance- 400 spectrophotometer for Proton ^lH shifts measurements. Chemical shifts are given in parts per million depending on the chemical shift of the dimethyl sulfoxide (DMSO) solvent.

Table 1 shows the main characteristic bands of EM biocide structure, as well as its functionalized counterpart, EM-NCO. It is possible, from the data provided in Table 1, to observe multiple bands at higher frequencies (> 3000 cm^-1), characteristic of amines stretch (N-H) , and at lower frequencies, the characteristic bands of aromatic amines, ranging from 1110 and 1180 cm^-1, this is, attributed to the C-N bonds stretching. These bands attributed to stretching of the amine attached to the benzene ring of the EM structure, disappears when the biocide functionalization occurs with the reactive NCO function, resulting in the appearance of a new band (maximum at 2254 cm^-1) , characteristic of the NCO stretch group. This bands replacement suggests that the bind between the NCO groups, from the diisocyanate, with the reactive amine CNH) function from EM, occurred. This functionalization is in fact confirmed through the HMR spectra analysis of the EM and its functionaliied counterpart.

Xn Table 2 the chemical shifts obtained from those NMR spectra analysis can be found, being possible to observe from the EM biocide spectrum, characteristic peaks of the benzene rings protons shifts and a peak at a chemical shift (8) of 13.74 ppm, attributed to the amine function of the EM structure. After functionalization of the EH biocide, it is possible to verify the additional appearance of peaks in its NMR spectrum, attributed to the protons of the two benzene rings from the diisocyanate (MOD molecule structure. It is also observed that the peak attributed to the EM amine disappears after its functionalization with HOI, suggesting its binding with one of the NCO functional groups from the diisocyanate molecule (MDI) . On the other hand, there is a peak attributed to the resulting amine binding, from the diisocyanate (NCO-R-NCO) with NH-EM, at a chemical shift of 8.54 ppm, confirming the occurrence of the functionalization, according to the simplified reaction:

Table 1. Analysis by infrared microscopy (FTIR) of the biocide 4-bromo-2- (4-chlorophenyl) -5- (trifluoromethyl) ~lH~pyrrol9-3- carbonitrile (EM) and EM-NCO functionalized biocide.

Table 2. Analysis by nuclear magnetic resonance (NMR) of the biocide 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl) -1H- pyrrole-3-carbonitrile (EM) and EM-NCO functionslized biocide.

Immobilization of the functionalized biocide

The ability of immobilization of the biocide with reactive isocyanate function was confirmed by ltd reaction with a polyol component (Desmophen 651 MPA/X, hydroxide content of 5.5±0.4%, Hempel A/S) usually used in the preparation of polyurethane based paint formulations. The reaction between the CK function from the polyol and the NCO from the functionalized biocide occurs, leading to urethane linkages:

Biocide-NCO + R'OH → RNH-CO-OR' (urethane)

The reaction was analyzed in the early stages and after 24 hours by using the Spectroscopy Fourier Transform Infrared (FTIR-ATR) in a frequency ranging from 500 and 4000 cm-*.

It was observed at the earlier stage of the reaction, the characteristic band of isocyanate functional biocide which appears at a maximum of 2254 cm^-1. After 24 hours of reaction, this characteristic band of the NCO functional group disappears, suggesting the occurrence of the chemical urethane bond formation, as expected.

It is essential to ensure that after the biocide functionalization its bioactivity remains. This is achieved by performing microbiological analyses. However, its bioactivity will only be fully confirmed after field trials, i.e., at a real environment. Example 3 illustrates specimens coated with antifouling paints, including^* functionalized biocides accordingly with the claimed process, after being tested in a real environment. In the microbiological analysis, biocides were tested in different media obtained from three species of microorganisms: Escherichia coll (E. coli), coagulase-positive Staphylococci and Pseudomonas aeruginosa, in accordance with the HPAw18, ISO .9308- 1, NP 4343: 1998 and XSO 6266, respectively.

In all analysis the results were negative, both for the original biocide and for the functionalized counterpart. (Table 3) , revealing that occurs a total growth inhibition of the tested microorganisms. This suggests that no bioactivity loss occurs after the biocide functionalization.

Table 3. Microbiological analyzes carried out on EM and EM-NCO biocides.

1 - MPN/g: Most probable number per gram of biocide;

2 - CFU/g: Colony forming unit per gram of biocide;

3 - EM * 4-bromo-2-(4~chlorophenyl)~5~(trifluo£omethyl}~lH~ pyrroie-3-carbonitriie♦ EXAMPLE 2

This second example intends to illustrate the functionalization of the commercial biocide 2- (tert-Butyiamino) -4- (cyclopropylamino) -6- (methylthio) -s-triazine (CAS No, 28X59-93- 0), named as IM in the present invention. This biocide is a diamine, thus possessing reactive amine function (NH) , which is compatible with isocyanate function (NCO) .

In a first step the previously dried biocide dissolution in butyl acetate (99.5%, Sigma-Aldrich5 is carried out, in order to obtain a solute concentration of 15 wt.%. The solution is then placed in a separatory funnel.

In a 3-necked flask the diisocyanate is placed. For this reaction the neat methylene diphenyl diisocyanate (MDI) was selected, in particular the 4, 4-MDI isomer. This diisocyanate is characterized by a molecular weight of 250.25 g/mol, a density of X.230 g/cm³ and an isocyanate content (NCO) of 33.4 t 0.1 wt.%. The flask is then heated and kept at a temperature of 45°C.

The amount of the used MDI was determined in order to guarantee a molar ratio NCO (MDI) /NH (biocide) = 1.06. In a second step the system is assembled, by attaching a mechanical stirring system, and a separatory funnel containing the blocidal solution. The entire system is then placed under an inert medium (under nitrogen). After stabilization (inert medium and stable temperature), the biocidal solution is added dropwise into the diisocyanate for about 10 hours under a continuous stirring rate of 385 rpm.

After 10 hours of reaction, and completed the addition of the biocide solution, the reaction condition are maintained for a period of not less than 30 minutes, ensuring the necessary reaction time.

Subsequently, the heating is ceased and the reaction mixture is left to cool till room temperature (20-23 °C) , keeping the stirring , after which is placed in a refrigerator for a period of about 12 hours in order to promote precipitation or the product reaction.

The obtained precipitate is then subjected to a drying process by solvent evaporation in a rotary evaporator at 60°C, and providing a gradual pressure reduction ranging front 40 mbar to C mbar. After the first drying it is followed a washing step with solvent and a further drying of the washed precipitate by evaporation under reduced pressure.

The isocyanate (NCO) mass content of the obtained functlonaiized biocide, named herein by IM-NCO and determined by an adopted standard method in ASTM D2572, was 9 ± 1%. It should be referred that depending on the molar ratio of the reaction between the diisocyanate and the biocide IM, it can be promoted or not, the full replacement of the two amine groups present in the IM structure. Under the described conditions/ a mixture of IM-NCO monofunctional and bifunctionai relatively the NCO functionality obtained.

Immobilization of the functional!zed biocide

The reaction of IM-NCO with polyol (Desmcphen 651 MPA/X, hydroxide content of 5.510.4%, Hempel A/S) was analyzed in the early stages of the reaction/ and after 24 hours, by Infrared Fourier Transformed Spectroscopy (FTIR-ATR), in a frequency ranging from 500 and 4000 cm^-3. Xt was observed at the earlier stage of the reaction_/ the characteristic band of isocyanate functional biocide_/ which appears at a maximum of 2272 cm^-1. After 24 hours of reaction, this characteristic band of the NCO functional group disappears, suggesting the occurrence of the chemical urethane bond formation, as expected. Bioactivity

Microbiological analyses were also performed in three different mediums obtained from three species of microorganisms: Escherichia coll (E. coli) , coaguiase-positive Staphylococci and Pseudomonas aeruginosa, in accordance with the HPAwlS, ISO 9308- 1, HB 4343: 1998 and ISO 6266, respectively. However, its bioactivity will only be fully confirmed after field trials tests, i.e., in a real environment, as will be illustrated in Example 3.

All microbiological analyses showed a complete inhibition of the microorganisms' growth (see Table 4), for both the original biccide and the functional!zed counterpart. This suggests that no bioactivity loss occurs after the biocide functionalization.

Table 4. Microbiological analyses carried out on IM and IM-NCC biocides.

1 - MPN/g: Most probable number per gram of biocide;

2 - CFU/g: Colony forming unit per gram of biocide;

3 - IM ^» 2-(tert-Butylamino) -4- (cyc!opropyiaminoj (methyithio) -s-t.ria2ine. EXAMPLE 3

The functionalized biocides prepared in accordance with the conditions described in examples 1 and 2, were tested in marine real environment_/ as antifouling additives in polyurethane based polymeric matrices (antifouling paints with two components) . The used components for the Hempel's paint Poiibest 55551 formulation preparation, by white colored were: a resin or base (Reference: 55559, Hempel A/5) and the suitable curing agent (reference 95370, Hempel A/S) . The proportions by volume of the components used were those recommended by the supplier (2/1 of base/curing agent) .

The immobilization of the biocide in the polymeric matrix was performed by firstly dissolving the biocide in a suitable pure and dehumidified solvent, followed by its addition and blending to the base component of the paint. In this example the methyl pyrrolidone (purity 99.5%, Acros Organics, CAS No. 872-50-4) was the selected solvent.

The biocide content in the solvent is determined as a function of the desired final biocide content in the final mixture (base

+ curing agent) .

The selection of the organic solvent must rely on its compatibility with the components of the polymeric matrix, and which allows obtaining high biocide solubility, in order to promote a minimum solvent content in the final polymeric mixture. Xt should also be noted that the mixing mode of the biocidal solution, as well as the paint application on specimens surfaces, follow conventional methods of preparation well-known and established in the field, and therefore, are easily performed by technicians or experts in the field. In particular their application can be performed by using a spray or brush For the tests performed in a marine environment, 10x10 cm grade steel specimens with a thickness of 6 mm were used. This type of steel is a material commonly used in ships' hulls, which was kindly provided by the Shipyard Estaleiros Navais de Peniche (ENP), Portugal. Alternatively, it can be used any other marine environment resistant material, such as rigid PVC, acrylic or fiberglass.

The coated specimens were tested in a fixed structure of fiber glass, further suspended by steel wires and immersed in Portuguese seawater in the ENP pontoon at Peniche with the following coordinates 39°21'06.6' 'N 9'22' 10.5* ¹ W. The test site is characterized as a quiet and far from the ships maneuvers zone, thus offering test conditions in a relative static medium, and with a maximum solar radiation exposure comprised between 12 and 18 hours, in the afternoon. These tests were performed in accordance with the ASTM D699G standard, and periodic inspections were performed in accordance with ASTM D3623-78a. It should be referred that the followed procedures allows to get a qualitative analysis, but also a quantitative behavior of the antifouling in the used coatings formulations on the samples immersed in seawater. For each inspection, the biofouling is monitored and recorded via visual and digital means, followed by their analysis, excluding about 1 cm in each side of the total surface area of the affected specimen.

In table 5 the formulations prepared and used to coat the specimens can be found, including the contents of the immobilized biocides in its polymeric matrix. The immersion of specimens was carried out to a depth of 3 meters, with an average temperature of 16 ± 1°C, salinity ranging from 35.2 to 36.7 (average density 1027 kg/m³) and an average pH of ¾.3.

In this sequence of tested specimens was also intended illustrate and find the best antifouling effect obtained the combined immobilization of two biocides in a paint formulation, in order to extend the range of action of the resulting coatings. It was also tested an antifouling commercial acrylic paint, and despite being a distinct polymeric matrix when compared to the prepared polyurethane based formulations_/ it allows to provide performances comparison with commonly used paints in the field. Additionally, and also for comparative purposes, two formulations containing a not immobilized biocide of recognized antifouling efficacy, zinc pyrithione (pesticide) , were also included.

It should be also noted that the formulations prepared did not suffer any optimization after the biocides Immobilization, but they can require adjustments in order to readjust the original physical-mechanical properties of a marine antifouling paint. Usually such optimizations, if needed, can be easily performed by experts in the field.

Table 5. Antifouling poiyurethane based paint formulations tested in marine environment.

elf-polishing paint with confidential composition;

2. Weight content in the total mixture of the uncured formulation, where EM * 4-broroo-2- (4-chlorophenyl) -5-

(trifluoromethyl) -lH-pyrrole-3-carbcnitrile and IM » 2- { tert-Butylaraino) ~4~ (cyclopropylamino) -6- (methylthio) -s- triazine;

3. Biocide ratio « EM-NCO/IM-NCO;

4. Test specimen 6 in which was included 1.7 wt,% 2inc pyrithione (pesticide not immobilized in the raatrix).

Specimens were inspected weekly and/or monthly depending on the evolution of biofouling. At each monthly inspection the specimens are smoothly washed with water. The analysis of the biofouling formed on the tested specimens was performed considering the density and type of fouling, based on two main stages of biofouling: a) Microfouling - Includes the first stage of marine biofouling formed by the physical adsorption of organic molecules (e.g. proteins, polysaccharides), a primary and reversible colonization of unicellular microorganisms (e.g. bacteria) and a secondary colonization of multicellular species (e.g. macroalgae spores). This microfouling forms the known biofilm/sliroe. It is also included at this stage of fouling, any type of debris/dust. And without any antifouling protection of the exposed surface, this physical microorganisms attack will occur within days or even hours .

b) MacroFouling - At this stage occurs the tertiary colonization, which includes fouling of macroorganisms, such as macroalgae, sponges, crustaceans, molluscs, etc. Without any antifouling protection of the exposed surface, this laacrofouling will occur after a few days, between 1 to 2 weeks.

Representative images of the specimens immersed in the seawater for periods ranging from 1 month to 3.5 months, can be found in Figures 1, 2 and 3. These images were processed using the program Sigma Scan Fro 5 in order to obtain negatives of the photos, which allowed obtaining a color contrast and a more assertive quantification of the specimen area affected by biofouling. On the other hand, and in accordance with the standard ASTM 06390-05, it was possible to determine the antifouling performance index of the surfaces, APT {Antifouling Performance Indexi .

This index is given by: API = 100 - (0.2 x covered area by the biofilm/sludge + 0.5 x covered area by seaweed/animal with a size less than 5 mm + 15 x covered area by seaweed/animal with a size exceeding 5 mm) . Later this API index can be classified into four distinct groups, in accordance with the following table (algorithm based on numerical evaluation of biofouling using the standard ASTM D699C-05) : Table 6: Algorithm of API Antifouling Performance Index_*

In accordance with the above description and from the analyses of the exposed specimens, the affected areas by biofouling, as well as their correspondent antifouling performance index, for a total immersion period of 3.5 months (Table 7) were obtained. The determination of API is simplified, being given by: 100 - 0,2 x area covered by the biofilm/sludge, since only the biofilm fouling/sludge in the exposed specimens was observed.

Table 7. Performance of the antifouling paints containing immobilized biocides.

From Table 7 it can be observed that polyurethane based paints containing immobilized biocide, exposed for about 3.5 months at static conditions, can reach excellent ancifouling performance. These results are similar to the commercial paints antifouling performances for the same period of immersion, with the advantage of avoiding the leaching of toxic agents into the environment. Specimens 6 and 9 were coated with paints containing non-immobilized biocides, and therefore and most probably they were released during the immersion time, thus leading to a gradual bioactivity loss and increase of. the affected area. It is also concluded that, and for the conditions and biota medium of the immersion tests, a ratio of EM-NCO/IM-NCO between 1 and 1.5, with minimum biocide mass contents ranging from 4 to 6 %, are the most promising parameters for the studied antifouling systems.

EXAMPLE 4

This last example is intended to illustrate the immobilization of functionaiized biocides in a silicone based matrix, as well as, to assess the effect of the immobilization of more than one biocide in the polymeric matrix, as a function of the total content of biocides. The immobilization was carried out following a procedure similar to the one described in example 3, with the exception of the used components, in this suitable for the preparation of the silicone based paint (HEMPASIL X3 87500, Hempei A/S) : resin or reference base: 87509 and the reference crosslinker 99950.

The proportions given in volume of the components used were those recommended by the supplier (17.8/ 2.2 of base/curing agent) .

The immobilization of the biocides in the polymeric matrix was carried out by a prior dissolution of the biocide in a pure and dehumidified suitable solvent, followed by their addition and blending into the base component of the paint. In this example, methyl pyrrolidone (purity 99.5%, Acros Organics, CAS No. 372- 50-4) was used as solvent. The prepared formulations (Table 7) were then used to coat specimens of PVC (poiyvinylchloride) with dimensions of 10x10 cm, and a thickness of 6 mm.

The coated specimens were tested in a fixed structure of fiber glass, further suspended by steel wires and immersed in Portuguese seawater in the ENP pontoon at Peniche with the following coordinates 39°21'06.6' 'Ν 9*22^,10.5^,' W. The test site is characterized as a quiet and far front the ships maneuvers zone, thus offering test conditions in a relative static medium, and with a maximum solar radiation exposure comprised between 12 and 18 hours, in the afternoon. These tests were performed in accordance with the ASTM D6990 standard, and periodic inspections were performed in accordance with ASTM D3623-^'?$a. The immersion of specimens was carried out to a depth of 3 meters, with an average temperature of 22 ± 1 °C, a salinity ranging from 3S.2 to 36.7 (mean density 1027 kg/m³) and an average pH of 8.3. Table 8» Formulations of the antifouling silicone based paints tested in marine environment.

.1. Mass content in the total mixture of the uncured formulation, where EM ^« 4-bromo-2- H-chlorophenyl) -5- (trifluoromethyl) -lH-pyrrole-.3-carhonitrile and IM « 2-

(tert-Butylamino) -4- (cyclopropylamino) -6- (methyithio) triazine;

Biocide ratio - EM-KCG/IM-NCQ. Specimens were inspected weekly and/or monthly, depending on the evolution of biofouling. At each monthly inspection the test specimens were smoothly washed with water. The analysis of the formed biofouling on the tested specimens was performed considering the density and type of fouling, in accordance with the procedure described in example 3.

Representative images of the specimens coated with silicone based formulations, after being immersed in Portuguese seawater for a total period of 2.5 months are shown in Figure 4. In this figure it is possible to verify that after 2.5 months significant biofouling on specimens is not observed. The observed attached algae are growing around the specimens, i.e., in the structure support. Nonetheless, it was possible to observe that the formulations containing mixtures of biocides, specimen 6, seems to be the cleanest when compared to the others, including the control (paint without biocides) .

Bibliographic references tlj T. R. Bott, Industrial Biofouling, 1st ed., Elsevier Publisher, UK, 2011.

(2) J. Chan, S, Wong, Biofouling Types, Impact and Anti.-Fouling, Pollution Science, Technology and Abatement Series, Nova Science Publishers, Inc. New York, 2009.

(3) J. A. Callow, M. E. Callow, Nature Commun . 2 (2011} 1-10. 14) M. P. Schultx, Biofouling 23 (2007) 331-341.

f51 M. A. Champ, Sci. Total Environ. 258 (2000) 21-71.

*

(6) M. P.Schultz, -J. A. Bendick, E. P. Holm, W. M. Hertel, Biofouling 27 (2011) 87 - 93.

f7) International Maritime Organization, MEPC 59/XNF.lC, 2009.

Claims

CLAIMS 1. Functionalization process for biocide immobilization in polymeric matrices, characterized in that it contains the following steps:

(a) Biocide dissolution in a pure and dehumidified solvent, nonpoiar and aprctic;

(b) Reaction of biocide functionalization between the solution containing the biocide,

with reactive function compatible with isocyanate function, and a diisocyanate, under an inert environment and at a pressure of 1 bar;

(c) Formation and precipitation of the product reaction, with a isocyanate reactive functional biocide mass content between 90-35%, which occurs spontaneously during the reaction, or after cooling, or can also be induced at the end of the reaction by in situ solvent distillation;

(d) Decantation and drying of the precipitate by solvent evaporation under reduced pressure;

(e) Mashing of the precipitate, obtained in step d) , with a suitable solvent, followed by a new drying process step; optionally

(f) Dispersion or dissolution of the functionalized biocide in a suitable solvent.

2. Process according* to claim 1, characterized in that the reaction of functionalization occurs with the addition and mixing of the biocide solution with a diisocyanate kept at a temperature between 40 and 90 °C.

3. Process according to claim 2, characterized in that the reaction of functionalization is carried out at a stirring speed between 350 to 500 rpm.

4 . Process according to any of the claims 1 to 3, characterized in that the reaction of functionalization is carried out with molar ratios of isocyanate functional/reactive function of the biocide between 1:0.5 and 1:1.

5. Process according to claim 4 , characterized in that the reaction of functionalization is carried out with molar ratios of isocyanate functional/reactive function of the biocide between 1:0.8 and 1:1.

6. Process according to any of the claims 1 to 5, characterized in that the reaction of functionalization is carried out for periods of time between 7 and 11 hours.

7. Process according to any of the claims 1 to 6, characterized in that it uses a pure diisocyanate with an isocyanate mass content between 25 and 35%.

8. Process according to any of the claims 1 to 7, characterized in that the solvent distillation is induced by a gradual reaction temperature increase, with a heating rate between 1 to 3°C/min.

9. Process according to claim 8, characterized in that the solvent distillation is induced by a gradual temperature increase, up to a maximum between 80-50 °C, and a distilled solvent volume not exceeding 1/2 of. the total used solvent, volume.

10. Functionalized biocides with reactive isocyanate function, produced according to the process defined in claims 1 to 10, characterized in that they are applied:

(a)- in a solid state, or;

(b) in a concentrated solution with a compatible solvent, or;

(c) in a concentrated dispersion.

11. Use of functionalized biocides, produced according to the process defined in claims 1 to 9, characterized in that their application can be performed as ingredients in formulations of paints, varnishes and/or in the composition of polymer-based materials, used in particular as protecting antifouling products:

(a) ship hulls;

(b) aquaculture marine structures;

(c) platforms, among others;

(d) circuits pipelines in contact with water, fresh or seawater, filters, packaging, medical materials, among others.