Preparation And Properties Of Thermochromic And Photochromic Coatings On Wood And Metal Substrates

Wood materials and metal materials are indispensable materials for furniture production and manufacturing.Wood is a natural material with natural texture,beautiful appearance,realistic image,good hand feeling,easy processing and coloring.Metal materials are solid and durable,hard and plastic,which makes furniture concise,straight and rational.Furniture is inseparable from coatings.The paint film on the surface of furniture can not only effectively enhance the aesthetics of wood products,but also effectively protect furniture from environmental factors and prolong its service life.With the development of science and technology,people’s demand for functional coatings for furniture is more and more vigorous,among which discoloration coating is one of the hot topics.Coatings can be divided into thermochromic coatings and photochromic coatings.Microcapsule technology has become the main research object of color changing coatings because it can effectively protect the color changing core material and prolong the color changing effect.In this paper,thermochromic microcapsules with core material of color changing compound and wall material of urea formaldehyde resin were prepared,and they were used in coatings and coated on the most common wood and metal substrates on furniture to explore the influence of microcapsule content(W_microcapsule)on the performance of paint film on different substrates.Similarly,photochromic microcapsules were applied to coatings and coated on two substrates to explore the effect of W_microcapsuleon the performance of paint film.Finally,the influence of the coating sequence of photochromic microcapsules and thermochromic microcapsules on the performance of paint film were explored,in order to prepare the best intelligent paint film with photochromic and thermochromic functions.The main research contents of this paper are as follows:（1）The thermochromic compound（microcapsule core material）was prepared by orthogonal experiment.The thermochromic temperature was taken as the result of experimental analysis,it was found that when the ratio of crystal violet lactone:bisphenol A:tetradecanol was1:3:60 and reacts in a 90℃ water bath for 1.5h,the performance of the thermochromic compound was the best,and the thermochromic temperature was 25℃.（2）Thermochromic microcapsules were prepared by in-situ polymerization.Taking the coating rate of microcapsules as the experimental results,it was found that when the M_{core material}:M_{wall material}was 4:7,the concentration of emulsifier was 5%and the rotating speed was 1600 rpm,the coating rate of microcapsules was the highest,and the n_urea:n_formaldehydehad the greatest influence on the coating rate.The single factor optimization experiment was carried out with the n_urea:n_formaldehyde.The comprehensive analysis showed that the performance of microcapsules was better when n _urea:n _formaldehydewas 1:1.6.At this time,the thermochromic temperature of microcapsules is 65℃.（3）The effects of different contents of thermochromic microcapsules on the properties of paint film were explored.The optical properties（color difference,gloss）,mechanical properties（hardness,adhesion,impact resistance）,liquid resistance and aging resistance of the paint film were tested.The test results showed that the performance of the paint film was the best when the W_microcapsulewas 20.0%on wood substrate and 10.0%on metal substrate.（4）The effects of different content of photochromic microcapsules on the properties of paint film were explored.The optical properties,mechanical properties,aging resistance and liquid resistance of the paint film were explored.It was concluded that the performance of the paint film was the best when the W_microcapsulewas 15.0%on wood substrate and 10.0%on metal substrate.（5）The effect of the coating sequence of thermochromic microcapsules and photochromic microcapsules on the performance of paint film were explored.The effects of the three kinds of paint films（Photochromic microcapsules were coated with primer and thermochromic microcapsules were coated with finish;thermochromic microcapsules were coated with primer and photochromic microcapsules were coated with finish;two kinds microcapsules were added at the same time）on optical,mechanical,roughness,cold-resistant liquid and aging resistance of the paint film.Comprehensive analysis showed that the paint film had the best performance when the thermochromic microcapsules and photochromic microcapsules were mixed on wood and metal substrates.