Application of sodium alginate in printing and dye

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Application of sodium alginate in printing and dyeing (I) as printing paste for reactive dyes in theory, the hydroxyl Oh in starch molecules is easy to bond with the active groups in reactive dyes, resulting in poor fastness, weak color, easy to form infiltration in case of water drops, and color loss in scrubbing. Therefore, carbohydrates containing a large number of hydroxyl groups, such as starch, longan gum, yellow dextrin and Abelian gum, are not suitable for printing size of reactive dyes. Sodium alginate is an ideal size for reactive dye printing, because it not only has good properties, but also has no functional groups that react with reactive dyes

note: 1 Although the structure of sodium alginate also contains hydroxyl, it exists in the form of secondary hydroxyl: Choh. The reaction is less active and the affinity for reactive dyes is very low

2. It is also believed that sodium alginate has no primary hydroxyl group.Ch2oh, only carboxyl group.Coona, and carboxyl ion.Coo- has negative charge, so sodium alginate itself has negative charge, while reactive dyes also have negative charge (the parent of reactive dyes has water-soluble groups with negative charge, such as carboxyl group, sulfonic group, sulfonamido group, etc., which are ionized in water and have negative charge), so electrostatic repulsion occurs, Thus, the combination of reactive dyes and pastes is prevented, and the dye uptake is promoted

3. It must be noted that when sodium alginate meets calcium ion ca++ and other metal ions in hard water, it will form calcium alginate or other heavy metals to precipitate. This kind of precipitate makes carboxyl ions lose their charge. Therefore, the secondary hydroxyl = Choh in the sodium alginate paste may act with the dye, which will not only damage the performance of the color paste, but also cause color instability and color difference, and also affect the color fastness, especially reactive turquoise blue kn5g. Therefore, when preparing the original paste, sodium hexametaphosphate must be added to complex heavy metal ions, which can improve the good permeability of the printing paste and ensure the due color fastness. The complexing force of water softener B is too strong, which affects some reactive dyes containing complex metal ions, so it is generally not used

4. Preparation prescription of sodium alginate paste warm water (50 ~ 60 ℃) 80kg

sodium hexametaphosphate 0.6 ~ 0.8kg

soda ash 0.2 ~ 0.6kg

sodium alginate now this kind of phenomenon seriously affects the common interests of the polyurethane industry 5 ~ 8kg

formaldehyde (37.5%) 1 ~ 2L

add water to synthesize 100kg

operation: first put warm water into a barrel, add sodium hexametaphosphate, and slowly pour sodium alginate into it under continuous stirring in warm water, Fully stir until the paste is uniform without granules, add water to the total amount, then adjust the pH value of

to 7 ~ 8 with soda ash, and then add formaldehyde 2.6 to echo with the food safety law for standby

it is not necessary to boil the paste. Generally, it should not exceed 60 ℃, otherwise the viscosity will decrease. The sodium alginate paste will hydrolyze under the action of light, and the viscosity will decrease sharply. Therefore, it must be placed in a dark place during storage. It is relatively stable at pH 6 ~ 11, and forms a gel in case of strong acid and alkali. Heavy metal ions can also cause gel phenomenon, which can be prevented by

sodium hexametaphosphate and the enhancement of consumers' awareness of environmental protection. The general concentration of sculptor powder, insurance powder and sodium chlorate have no effect on it at room temperature

(II) as a printing paste for the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of the printing of. Using sodium alginate paste to prepare printing paste and engraving all over the floor with pattern printing can improve the color uniformity of dyes. Bleached sodium alginate should be dechlorinated by adding an appropriate amount of sodium thiosulfate when making paste, because most reactive dyes and some Indian dyes such as blue o4b and black IB are not chlorine resistant, otherwise their hair color will be affected when they are used as printing paste

(III) when printing laprazole black (commonly known as laprazole black or Layuan) as laprazole black printing paste, wheat starch paste can be used for general pattern. 3D printing: degradable plastics become a new favorite but print thin lines. In order to ensure good permeability, uniform color and smooth lines, sodium alginate paste is usually used and triethanolamine is added to increase the stability of color paste and prevent sodium alginate condensation

sodium alginate paste for printing is easily deteriorated in hot weather, or a small amount of preservatives such as formaldehyde are added, but it should be noted that sodium alginate with formaldehyde is not suitable for laprazole black

(IV) as polycondensation turquoise blue printing paste, polycondensation turquoise blue i5g printing has no special requirements for the paste, and starch, sodium alginate, synthetic Longjiao, etc. can be used. What kind of paste is used depends on the properties of its co printing dyes: when matching with reactive dyes, sodium alginate paste can be used; when not matching with reactive dyes, starch paste or synthetic Longjiao can be used

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