The Research On The Staining Characteristics And Technology Of The Bamboo Bundles With Reactive Dyes

Recombinant bamboo lumber is one of the bamboo manufactured board, which consisted of crushed bamboo bundles. As the basic units of recombinant bamboo lumber, the crushed bamboo bundles are treated through drying, dipping with adhesive, setting along as the bamboo textures, and finally through hot pressing (or cold pressing then heat curing) to obtain the recombinant bamboo board. Because of its superior physical and mechanics performance and pretty decorative affection, it has obtained the rapid development in recent years, which has been widely applied in the field of floor, furniture decoration and structure materials, etc. Nowadays, the demand of recombinant bamboo has been improved with the agreement from domestic and foreign markets on recombinant bamboo, while it is difficult to meet the various requirements of consumers on decorative performance of bamboo products because of that it’s only including original, charring and bleaching colors.In this study, we used reactive dyes to stain bamboo bundles which were worked as objective, and discussed the technology and properties of dyeing bamboo bundles with reactive dyes. Then it can enrich the affection in decoration and extend the application field of recombinant bamboo, which would play an important role in increasing added-value of recombinant bamboo products. Moreover, the results of this research would provide theoretical guidance and scientific basis for the establishment of dyeing and hot pressing treatment for various recombinant bamboos, the main research conclusions are as follows:(1) Different kinds of pretreatment including acid, dilute alkali (NaOH) and hot water could effectively improve the dyeing rate of bamboo bundles, with the increase of concentration of acid, the dyeing rate decrease after an initial increase, the highest dyeing rate appeared in the concentration of 1.2%, which increased about 15.3% compared to the concentration of 0.6%; The highest dyeing rate appeared in the concentration of NaOH in 2.1%, which mostly approached to 48.8%. The effect of dyeing pretreatment time with acid, dilute alkali and hot water were not significant, when dyeing pretreatment time ranged from 1 to 6 hr(s), the fluctuation of dyeing rate was about 6%,8% and 5%, respectively. With higher liquid pretreatment temperature, there appeared the higher dyeing rate, and it reached to 41.8% and 53.1% when the temperature raised to 100℃ respectively, while it showed a slightly increasing in dyeing rate with higher hot water pretreatment temperature, but the maximum growth was not exceeded 6%. Considered all above three methods for bamboo pretreatment, alkali treatment was best and improve dyeing rate more than 35% and the optimum pretreatment process conditions as follows:the concentration of NaOH, temperature and time is 2.1%,100℃ and 1n, respectively.(2)The concentrations of Na2SO4 and Na2CO3 and duration time had significant impact on both dyeing and fixation rates, while had little impact on bundle weathering color fastness and the average color deviation valued accounts for less than 3NBS.With the increasing concentrations of Na2SO4 and Na2CO3, both dyeing and fixation rates tend to rise, which reached increment of 38.6%、21% and 29.2%、21%, thus the optimal concentrations was 60 g/L and 20g/L, respectively. With extending of time, dyeing and fixation rates of bundles increased at the first stage and then remain stable. When treating bamboo bundles within 0.5-2.0 hours, extending the time had influential effect on both dyeing and fixation rates with highest value of 21.2%; With exceeding dyeing time to 6h, the dyeing and fixation rates tend to be steady. The optimized treatment conditions of dye process are 60g/L Na2SO4 concentration and 20g/LNa2CO3 concentration and 2h duration time.(3) Ultrasonic and impress treatment worked as an effective method to improve the dyeing rate and the weather resistant fastness of dyed bamboo bundles compared to normal pressure dyeing treatment, the dyeing rate of ultrasonic auxiliary dyeing increased by 7.1% on average, and the impress dyeing treatment can effectively shorten dyeing duration with the same result of dyeing rate. The color difference after sunlight decreased 2.40 NBS and 2.01 NBS, respectively.(4) Dyeing bamboo scramblers had good physical properties under our experiment, while the thickness swelling need to be further improved The range of MOE in bamboo scrambler lies between 90Eb-150Eb; MOR had reached premium product standard; Horizontal shear strength reached above 12V-15H range; Thickness swelling expansion rate basically reaches T15.0 range. Based on range analysis, pressing temperature had most great impact on MOE, MOR and vertical shear strength; Pressing time had most great impact on thickness swelling expansion rate; Design density had most great influence on vertical shear strength. In our experimental conditions, with the increase of pressing temperature, pressing time and design density, physical and mechanical properties of dyeing recombinant bamboo show a tendency to rise, therefore the optimal dyeing processing parameters are 160℃、1.2min/mm and 1.05 g/cm3.