People who often use addition-type liquid silicone raw materials for molding or potting often encounter non-curing or non-curing and sticky contact surfaces. After inquiring, the answer is that it is caused by platinum catalyst poisoning. Many people are at a loss when they hear such professional terms. Let me give you an in-depth analysis of the reasons why the addition-type silica gel platinum catalyst is poisoned and not solidified.
Definition of poisoning: The phenomenon that the catalytic activity of a catalyst declines or loses due to the action of certain substances is called catalyst poisoning. These substances are called toxins. Poisons are usually impurities brought into the reaction raw materials, or some impurities in the catalyst itself; reaction products or by-products may also poison the catalyst.
Poisoning principle: A small amount of impurities contained in the catalyst raw materials are either strongly adsorbed (mostly chemical adsorption) on the active center, or chemically interact with the active center to become other substances, thereby poisoning the active center. The severity of "poisoning" is determined by the type and amount of chemicals exposed.
Poisoning substances: For platinum catalysts, catalyst poisons mainly include S, Se, Te, As, Sb, Bi, Zn compounds, halides, etc. Common poisoning substances for addition-type platinum silicone include oil sludge, clay, putty, solder, photosensitive resin, 3D printing (occasionally), etc. The following are common substances that are likely to cause poisoning of platinum catalysts.
1. Amines and amino compounds: neutralized amine, ethanolamine, N-methylethanolamine, triethanolamine N-dimethylethanolamine, n-butylamine, diethylamine, triethylamine, tetramethylenediamine (butyl diamine), cyclohexylamine, melamine, dimethylformamide, nitriles, cyanate esters, oximes, nitroso compounds, hydrazino compounds, azo compounds, adiponitrile, methylethyl, nitroso , chelates, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid.
2. Sulfur-containing components: dimethyl di, ethanethiol acid, allyl thiourea, etc.
3. Tin-containing components: fatty acid tin salt, organic tin curing agent.
4. Phosphorus-containing components: triphenylphosphine, phosphite, triethyl phosphite.
5. Containing arsenic, antimony, selenium and tellurium: triphenylarsine, triphenyl stilbene, chlorobenzene carboxymethyl selenide.
6. Residual solvents or monomers: ethanol, methanol, ethyl acetate, vinyl acetate.
7. Primer coating material: clay coating glue with polyethylene acetate or acrylic latex as adhesive, coating glue containing calcium carbonate, natural rubber latex/clay, latex/ethylated starch, styrene/acrylic acid , polyvinyl acetate, polyvinyl acetate/acrylic acid.
About platinum catalyst, please check the details:
https://www.siliconefoam.net/product-platinum-catalyst-.html
