Preparation And Performances Of TD Silicone Modified Epoxy Connecting Layer Resin

According to the adhesion mechanism of marine fouling organisms,organosilicon fouling release antifouling coating（SFRC）can effectively reduce the adhesion strength of marine fouling organisms on their surface and inhibit the attachment of fouling organisms by using its own characteristics,which has the advantages of environmental friendliness and long antifouling period,and has broad application prospects.However,due to,the significant difference in the material composition and chemical structure of the film-forming resin used in SFRC and epoxy primers,and the compatibility between them is weak,SFRC is directly coated on the surface of epoxy anti-corrosion primer,which is easy to detachment and failure under application conditions of alternating dryness and wetness or pressure changes,and therefore an intermediate linking layer is required to form a matching system between the organosilicon fouling release coating and the epoxy anti-corrosion primer,in order to better exert the fouling prevention effect of SFRC.In this paper,we conducted research on the preparation and performance evaluation of TD organosilicon-modified epoxy linking layer resin,targeting the surface characteristics of ship underwater general-purpose epoxy anti-corrosion primer and fouling-release organosilicon topcoat.The organosilicon D-type monomer belongs to bifunctional silane,and the polymerized long chain has flexible characteristics.The organosilicon T-type monomer is a trifunctional silane,which belongs to the cross-linking unit in silicone resin,providing more cross-linking points for its combination with the organosilicon topcoat,fully leveraging the advantages of TD-type organosilicon resin,such as multi-active terminal groups,flexible main chain,and good compatibility with the organosilicon topcoat.Through orthogonal experimental design,the reaction conditions of TD-type silicone resin were explored with the viscosity of TD-type silicone resin as a reference.It was found that the optimal reaction conditions for TD-type silicone resin were as follows:heating 65°C,p H 5,water consumption was 0.8 times the theoretical water consumption,and reaction duration was3 h.TD type organosilicon resin was prepared under the optimal reaction conditions,and its was characterized by FT-IR and TG.The Si-OH vibration absorption peak of the reactant disappeared at 3400 cm^-1,while the Si-O-C peak of TD type organosilicon resin at 1030～1200cm^-1 was enhanced.The molecular weight of the product was analyzed by gel permeation chromatography（GPC）,and the results showed that the molecular weight of the product was more than 7 times that of the reactant,proving the synthesis of the organosilicon resin.The preparation of TD-type organosilicon epoxy resin through physical blending and chemical bonding of TD-type organosilicon resin and different hydroxy value epoxy resins.By adjusting the content of phenyl components the TD-type organosilicon resin,the compatibility between organosilicon resin and epoxy resin was improved.The study found that with the increase of phenyl content,the compatibility gradually increased,and the organosilicon resin A with higher phenyl content exhibited good compatibility with E51 and E44.The degree of condensation reaction of the two resins in the chemical modification preparation was characterized by FT-IR.The results showed that with the increase of phenyl content,the degree of condensation reaction gradually increased,The comprehensive mechanical properties of the synthesized resin were determined by a material comprehensive performance testing machine,and the surface energy of the cured resin was measured by a contact angle measuring instrument.The results showed that the elastic modulus of organosilicon physical blend epoxy resin was between 41.68～121.94 Mpa and the surface energy was about 27.35 m J/m².The elastic modulus of chemically condensed epoxy resin was 2.39 Mpa～30.06 MPa,and the surface energy was25.58 m J/m².The surface energy of the organosilicon-modified epoxy resin prepared by the two methods is between the epoxy primer and the organosilicon topcoat,meeting the coating wetting requirements of the connection layer,the epoxy primer,and the organosilicon topcoat.AP51（1:4）and AC51（1:4）were selected as the intermediate paint base resin for the preparation of matching connection coatings.Using TD type organosilicon-modified epoxy resin as the matrix resin,the formulation of joining paint was explored.It was found that with amino silicone resin as curing agent,the addition amount was 50%,and the adhesion of joining paint,topcoat and primer reached 1.28MPa and 4.0 MPa,respectively.Under the conditions of determining the type and amount of curing agent,a combination of 3%bis（aminoethyl）aminopropylsilane and 0.8%ethyl silicate was used as the adhesion promoter,resulting in a self-made connecting coating with a bonding strength of 1.59 MPa with the topcoat and 4.51 MPa with the epoxy primer.Further introduction of plastic as an adhesion promoter with an addition amount of 10%resulted in adhesion strengths between the connecting coating and the primer of 1.61 MPa and the topcoat of 4.30MPa,respectively.Finally,the connecting coating formulation was determined to use amino-functionalized silicone resin as the curing agent and bis（aminoethyl）aminopropylsilane,ethyl silicate,and plastic as the adhesion promoters.A marine immersion test was conducted with a coating system of anticorrosive primer-intermediate connecting coating-fouling release antifouling paint.After 7 d of immersion,there was no blistering or cracking observed on the test panel,and after 15 d,a small amount of bacterial growth was observed on the surface,with no blistering or cracking.The effect of the self-made intermediate connecting coating on the fouling resistance of the antifouling paint was explored by measuring the density of diatoms and Navicula spp.adhered to the coating,and the experimental results showed that the self-made connecting coating had no impact on the antifouling of the topcoat.