10. In printing and dyeing auxiliaries. How many types of penetrants are there? What are the requirements for each type of penetrant?
Answer Among printing and dyeing auxiliaries, penetrants have a wide range of uses and types. Generally, there are four classification methods. ①Classification by application process. Penetrants for pre-treatment (including: penetrants for desizing, penetrants for scouring, penetrants for bleaching, penetrants for silk finishing, penetrants for wool carbonization, etc.), penetrants for coloring, penetrants for printing, Penetrating agents are used for post-finishing. ②Classified according to application pH range. Strong alkali-resistant penetrant, weak alkali-resistant penetrant, near-neutral penetrant, weak acid-resistant penetrant, strong acid-resistant penetrant, etc. ③Classification according to ionic type. Non-ionic penetrants, anionic penetrants, compound penetrants, etc., zwitterionic and cationic penetrants are rarely used. ④ Classification according to raw material types. Sulfated castor oil, sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium alkyl sulfate, sodium secondary alkyl sulfonate, sodium secondary alkyl sulfate, sodium alpha alkenyl sulfonate, alkyl naphthalene sulfonate Sodium sulfate, sodium alkyl succinate sulfonate, sodium trypsin, sodium sulfamate, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyether, phosphate ester compounds, and alcohol compounds, Ketones, ethers, etc. Penetrants for printing and dyeing should be distinguished according to process requirements, mainly acid and alkali resistance requirements. Therefore, when using penetrants in dyeing and finishing production, the pH value of the solution and the content of inorganic salts must be considered. Otherwise, the solubility of the penetrant will be affected, and in severe cases, the penetrant will decompose. For example, among the penetrants used for pretreatment, some processes require a higher amount of alkali for scouring, some require alkali resistance of 50g/L NaOH, and some require alkali resistance below 20g/L; the silk-finishing penetrant requires alkali resistance of 260 ~280g/L NaOH. In strong alkaline solutions, generally non-ionic penetrants cannot be used, and anionic penetrants are generally available. Because anionic surfactants have a small relative molecular weight and are soluble in strong alkaline solutions, but those with ester groups such as penetrants Agent T cannot be used because alkali can saponify the ester. When preparing additives, it is important to understand the alkali resistance of various raw materials. Another example is the penetrant used for coloring. Since the pH value of the dye bath during coloring is generally between 5 and 8, the pH value of the resin finishing agent is generally acidic to neutral. This type of penetrant can be non-ionic or anionic. Some wool coloring and wool carbonization need to be used in strong acidic solutions. Most nonionic penetrants can be used, but most anionic penetrants cannot be used, especially sulfate ester salt anionic penetrants. If sodium lauryl sulfate is added to HCl or H2SO4 solution, it will decompose into dodecanol and Na2SO 4.
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