Study On Bleaching Mechanism And Dyeing Process Of Mansonia Altissima Wood

Manson Wutong has beautiful texture,slightly glossy surface,superior processing performance,and has the advantages of corrosion resistance and termite resistance.Its gray stained veneer is applied to high-end furniture veneer and interior decoration.Many furniture companies use gray stained veneer for production and manufacture,and its price can be increased by 60%after dyeing.Manson Wutong has a dark color and uneven wood color,so it needs to be bleached before dyeing.However,when using the conventional bleaching process to bleach Manson Wutong veneer,the residual "red tendons" will affect the dyeing effect.Taking Manson Wutong veneer as the research object,this paper solves the technical problem of Manson Wutong Veneer Bleaching residual "red tendons",and develops a continuous bleaching method that can remove the "red tendons" that are difficult to bleach.The effects of various influencing factors on bleaching and dyeing effects are studied through single factor test,and the bleaching and dyeing process parameters are optimized in combination with orthogonal and response tests.FT-IR,GC-MS and other methods were used to study the components of the "red tendon" residue of Manson Wutong bleached white wood,and to interpret the cause and removal mechanism of the "red tendon".The main research conclusions are as follows:(1)The effects of hydrogen peroxide concentration,bleaching temperature and bleaching time on the bleaching effect of Manson Wutong were investigated by single factor and orthogonal test,and the optimal process was obtained.The results showed that with the increase of hydrogen peroxide concentration and bleaching time,the whiteness difference and color difference of Manson Wutong veneer increased first and then tended to be flat,and the effect of bleaching temperature on whiteness difference increased first and then decreased.The maximum color difference and whiteness difference were 24.94NBS and 31.2%respectively.Combined with orthogonal experiment,the best pre sequence bleaching process is hydrogen peroxide concentration of 6%,bleaching temperature of 60℃,bleaching time of 60min.At this time,the color difference is 25.75NBS,and the whiteness difference is 33.23%.(2)By comparing the macro and micro morphology of the bleached "red bars" area,it was found that "red bars" were mostly distributed along the wood texture,and the color of the duct was darker.Hot water and benzene alcohol solution can extract chromogenic substances,and phenol and flavonoid compounds are contained in benzene alcohol extract of red tendon region and non red tendon region.The FT-IR results showed that the chemical components of wood flour and benzene alcohol extracts in the red gluten region were similar to those in the non red gluten region,and the content of phenols and aromatic substances in the red gluten region was high.Combined with the GC-MS results,it was found that the red gluten extract contained phenols containing conjugated chromogenic groups such as cis-1,2-dihydrocatechol.It is found that sodium hydroxide is the main reason for the formation of red ribs,and sodium hypochlorite can effectively reduce the color of the extract.(3)The effects of sodium hypochlorite concentration,bleaching temperature and bleaching time on chromaticity index and tensile strength along the grain were investigated by single factor test,fuzzy mathematics and orthogonal test.The results showed that with the increase of sodium hypochlorite concentration,bleaching temperature and bleaching time,the red green degree difference and tensile strength along the grain decreased,of which the red green degree difference decreased by 8.2 at the maximum and the tensile strength along the grain decreased by 23.77 MPa at the minimum.When the concentration of sodium hypochlorite is 6%,the bleaching temperature is 60℃,and the bleaching time is 40min,Δ a*is-6.9,σ is 57.88MPa,and the comprehensive score can reach 91.87.(4)The effects of dye concentration,dyeing time and dyeing temperature on the dye uptake were investigated by single factor and response surface methodology.The results showed that the dye uptake first increased and then decreased with the increase of dye concentration.When the dye concentration was 0.2%,the dye uptake reached 13.57%.With the increase of dyeing temperature and dyeing time,the dye uptake first increased and then leveled off.When the temperature was 90℃,the dye uptake reached 13.53%,When the dyeing time was 5h,the dye uptake was 13.29%.The optimum process of Manson Wutong veneer acid grey dye was obtained as follows:dye concentration 0.16%,dyeing time 4.6h,dyeing temperature 86℃,and the dye uptake could reach 14.09%.