Preparation And Application Of Self-matting Acrylate Coating

Self-matting varnishe is widely used in exterior coatings for buildings,matte finishes for paper prints and matte finishes for wooden furniture due to its excellent cost performance.Overcoat varnishes have a high degree of light reflection due to the absence of fillers,so general overcoat varnishes are mostly high-gloss coatings,but the protective coatings in many areas are matte coatings.Currently,micron-scale silica was generally used as the extinction component in self-matting acrylic coatings.However,although it has an excellent matting effect,it loses the high transmittance of the coating,resulting in color distortion and saturation of the covered items.In this paper,a cross-linked acrylate copolymer microsphere with water swelling and water shrinkage properties was prepared by micro-suspension polymerization,which applied to acrylic coatings.Because the composition and properties of the microspheres are similar to the film-forming substances of the coating,the resulting coating film not only has high light transmission after drying,but also has uneven surface(micron level)to make it have good matting performance,successfully solving the problem of the balance and uniformity of the coating's extinction and light transmission.It is expected to be used as a self-matting varnish,applied to the glazing coating of building exterior walls,the matte surfacing of paper prints and the matte surfacing of wooden furniture.The main work of this paper is as follows:1.Preparation and characterization of acrylate copolymer crosslinked microspheres.Acrylate microspheres with water swelling and water loss shrinkage properties are prepared through micro-suspension polymerization,with styrene(St)as the main monomer,methyl methacrylate(MMA),methacrylic acid(MAA)as a functional monomer,1,4-butanediol dimethacrylate(BGDMA)as a crosslinking monomer,hydroxypropyl methyl cellulose(HPMC)polyvinyl alcohol(PVA)as a composite dispersant and Benzoyl peroxide(BPO)as an initiator.Through the investigation of the influence of the reaction conditions,the amount of monomer,the proportion of dispersant and the amount of co-dispersant in the preparation process of microspheres on the polymerization reaction and the resulting product,we obtained:1)Acrylate copolymer microspheres with a particle size of 5± 3 ?m can be prepared,when the monomer mass ratio is St:(MMA+MAA):BGDMA=44.5:55.0:0.5,the amount of dispersant(mHPMC:mPVA=3:1)is 10.0wt%(accounting for the total amount of monomers,the same below),the dosage of the auxiliary stabilizer cetyl alcohol(CA)is 0.20wt%,the dosage of sodium nitrite is 0.15wt%,the amount of sodium dodecylbenzene sulfonate(SDBS)is 0.17wt%,and the amount of allyloxynonylphenol polyoxyethylene ether ammonium sulfate(SE-10N)is 0.50wt%.2)By adjusting the amount of methacrylic acid(5?40 wt%),the water absorption capacity and water loss shrinkage capacity of the microspheres can be adjusted.As the amount of MAA increases,the water absorption performance of the microspheres increases.3)Scanning electron microscopy was used to characterize the morphology of acrylate microspheres before and after drying.It was found that the microspheres had the characteristics of swelling and shrinkage due to water absorption,and the volume change rate of microspheres could reach about 30%.2.Application of acrylate copolymer crosslinked microspheres in coatings.The coating prepared by mixing microspheres and acrylate base emulsion was applied to the primer,and then the gloss,light transmittance,abrasion resistance and water resistance of the coating were tested.The results show that:1)With the increase of the amount of MAA in the microspheres,the matting performance of the coating has been improved to a certain extent.2)As the amount of microspheres(3?9 wt%)in the coating increases within a certain range,the matting performance of the coating is significantly improved.3)The coating showed excellent abrasion resistance and water resistance,and the coating had not changed after soaking in natural water for 60 days.4)The matting performance of the coating shows excellent effects while still maintaining good light transmittance.The comparison between before and after applying the overcoat paint revealed that the color of the overcoat used for the texture coating was not distorted.