Wetting acid agents

All wet strength agents are bi- or multi-functional molecules with the capability to cross-link with each other or with cellulose. The choice of chemistry depends to a large extent on pH. In acid systems, the main wet strength agents are urea-formaldehyde (U/F) and melamine-formaldehyde (M/F) resins, whereas in neutral and alkaline systems polyamine-polyamide-epichlorohydrin resins are more effective. However, these are not the only systems in use, and a summary of these and other available methods is provided in Figure 7.22. 

Unlike the urea- and melamine-formaldehyde resins, these wet strength agents are suitable for both neutral and alkaline pH. They are prepared by condensation of a dicarboxylic acid and bis (2-aminoethyl) amine, the free amino group is then alkylated with epichlorohydrin to give an aminochlorohydrin which exists in equilibrium with a 3-hydroxyazetidinium group (Figure 7.28). 

Aldehyde starches are prepared by treatment with periodic acid/periodate ions, which selectively oxidize the adjacent hydroxyl groups on carbon atoms 2 and 3 to aldehyde groups. Dialdehyde starch can react with cellulose by forming covalent hemiacetal and acetal bonds.40 It is primarily used as a wet strength agent in the production of tissue and other sanitary grades. 

CAS 61788-61-2 EINECS/ELINCS 262-989-7 Synonyms Fatty acids, tallow, methyl esters Definition Ester of methyl alcohol and tallow acid Uses Wetting/oiliness agent for metalworking and lubricating oils lubricant, plasticizer for cosmetics, leather, rubber prods. solvent for pesticides and herbicides in food-pkg. adhesives Regulatory FDA 21 CFR 175.105 Manuf/Distrib. Anar Mosselman NV Sea-Land Trade Names Exceparl MT... 

The PAFC and MCFC are similar types of fuel cell in that they both use a liquid electrolyte that is immobilised in a porous matrix. We have seen that in the PAFC, PTFE serves as a binder and wet-proofing agent to maintain the integrity of the electrode structure and to establish a stable electrolyte/gas interface in the porous electrode. The phosphoric acid is retained in a matrix of PTFF and SiC sandwiched between the anode and cathode. There are no materials available that are stable enough for use at MCFC temperatures that are comparable to PTFF. Thus, a different approach is needed to establish a stable electrolyte/gas interface in MCFC porous electrodes. The MCFC relies on a balance in capillary pressnres to establish the electrolyte interfacial boundaries in the porous electrodes (Maru and Marianowski, 1976 and Mitteldorf and Wilemski, 1984). This is illnstrated in Fignre 7.12. 

Treatment of long chain alkenes containing at least eight carbon atoms and one double bond, e.g. 1-hexadecene, with chlorosulfonic acid and then with 20% sodium hydroxide, yielded useful wetting/cleansing agents. 

In compound semiconductor processing, phosphoric acid is a common wet etching agent for example, in combination with hydrogen peroxide and water it is used to etch InGaAs selective to InP. 

Uses Wetting/rewetting agent for use as general dyeing assistants Features Stable to salts, acids, alkalis Rexowet VL [Emkay ]... 

Aerosol is also a trade name for certain wetting agents, most of which are esters of sodium sulphosuccinic acid. 

Naphthalenesulfonic acids are important chemical precursors for dye intermediates, wetting agents and dispersants, naphthols, and air-entrainment agents for concrete. The production of many intermediates used for making a2o, a2oic, and triphenylmethane dyes (qv) involves naphthalene sulfonation and one or more unit operations, eg, caustic fusion, nitration, reduction, or amination. 

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