Preparation Of Medium Temperature Water Soluble Hydroxypropyl Starch Sizing

At present,the sizing is made of high-temperature boiled pulp and high-temperature sizing process.The cooking temperature is 100~132 ?,and the slurry temperature is above 92 ?.The high-temperature boiled pulp and high-temperature sizing process consume large energy,and the sizing value is low in safety.Medium temperature sizing can significantly reduce heat energy consumption.In order to achieve medium temperature cooking and sizing,corn starch is used as raw material to prepare hydroxypropyl starch slurry which can be dissolved above65?in water system.The structure and various properties of the prepared slurry were characterized and tested,and the sizing practice was carried out.The specific research contents are as follows.(1)The process route for preparing medium-temperature water-soluble hydrox-ypropyl starch slurry(MTWSHPS)is: corn starch acidification?propylene oxide etherification.The acidification pretreatment process is: starch concentration of 45%,hydrochloric acid 3%,hydrolysis at 60 ? for 80min;hydroxypropylation process:adding 0.8% NaOH to starch milk,15% of propylene oxide is added twice After 5min interval,etherification at 45?for 18 h,after neutralization,the temperature was raised to 55?for 30 min.The prepared hydroxypropyl starch is water soluble at 65?.(2)It was found by FTIR and hydrogen spectrum analysis that a hydroxypropyl group was successfully introduced into the synthesized slurry,and the prepared slurry was a hydroxypropyl starch slurry.(3)It can be seen from SEM,XRD and TGA analysis that the introduction of hydroxypropyl groups in starch increases steric hindrance and destroys the association of hydrogen bonds between corn starch hydroxy groups,resulting in a significant decrease in the crystallinity of starch.The gelatinization temperature is lowered,and the surface structure of the slurry is loose,which is favorable for water molecules to enter the interior of the starch,and it is water-soluble at 65?.(4)By testing the basic properties,slurry and film properties of the medium-temperature water-soluble hydroxypropyl starch slurry,it can be seen that the MTWSHPS slurry has excellent viscosity and thermal stability;the film formation is good,the performance is excellent,it is easy to desizing,and it has good miscibility with poly acrylic sizing.(5)The medium temperature sizing process was studied.In view of the problem of large surface tension and poor slurry permeability at medium temperature,the process of adding an anionic penetrant to the slurry reduces the surface tension of the slurry and improves the penetration of the slurry into the yarn.By investigating the relationship between the amount of anion penetrant and the viscosity of the slurry,the adhesion of the slurry and the performance of the serosa,the amount of anionic wetting penetrant was 0.2%.(6)The sizing process of medium temperature pure cotton yarn and polyester cotton yarn was studied.By testing the viscosity and adhesion of the slurry,the ratio of the medium temperature water-soluble hydroxypropyl starch slurry to the liquid propylene slurry at the time of pure cotton sizing was 80:20.When the polyester cotton yarn is sizing,the ratio of the medium temperature water-soluble hydroxypropyl starch slurry to the liquid propylene slurry is 70:30.(7)Medium temperature sizing and high temperature sizing were performed on14.6 tex pure cotton yarn and polyester cotton yarn,respectively.By testing the physical and mechanical properties of the original yarn and sizing,it is concluded that the performance of the medium temperature sizing yarn is close to the high temperature sizing performance after adding the anionic wetting penetrant,which can meet the yarn requirements for warp weaving.Figure 25,table40,reference 85.