Urethane cross-linking agents

Polymers. AH nitro alcohols are sources of formaldehyde for cross-linking in polymers of urea, melamine, phenols, resorcinol, etc (see Amino RESINS AND PLASTICS). Nitrodiols and 2-hydroxymethyl-2-nitro-l,3-propanediol can be used as polyols to form polyester or polyurethane products (see Polyesters Urethane polymers). 2-Methyl-2-nitro-l-propanol is used in tires to promote the adhesion of mbber to tire cord (qv). Nitro alcohols are used as hardening agents in photographic processes, and 2-hydroxymethyl-2-nitro-l,3-propanediol is a cross-linking agent for starch adhesives, polyamides, urea resins, or wool, and in tanning operations (17—25). Wrinkle-resistant fabric with reduced free formaldehyde content is obtained by treatment with... 

NR can be cross-linked by a blocked diphenyl methanes diisocyanate to produce urethane crosslinks. The cross-linking agent dissociates into two quinonedioxime molecules and one diphenyl methane diisocyanate. The quinone reacts with the rubber via a nitroso group and forms cross-links via diisocyanato group. The performance of this system in NR is characterized by excellent age resistance and outstanding reversion resistance. 

Urethane is used as a solvent for various organic materials, pesticides, and fumigants. It is also used as a chemical intermediate in the production of cross-linking agents in textiles and pharmaceutical industry. Urethane was once used as an anesthetic in veterinary medicine. Its veterinary use was discontinued in 1948 when its carcinogenic properties were revealed. 

Use Lubricants, plasticizers, paint and varnish vehicles, gelling agents, urethane intermediates, adhesives, cross-linking agents, humectants, textile fiber finishes, functional fluids, surface-active agents, dispersants and emulsifiers in foods, pharmaceuticals, cosmetic preparations. 

Use Cross-linking agent and catalyst in urethane foams, epoxy resin curing, metal complexes, intermediate. 

Figure 4. The high-temperature shear storage and loss moduli of Halthane 73-14 and 73-19 adhesives are controlled by the presence or absence of the cross-linking agent quadrol in the hard segments. In the linear urethane (73-14), viscous flow follows the melting of the hard segments, whereas in the cross-linked urethane (73-19), the modulus drops only when the polymer begins to degrade.

The principal components of commercially available urethane coatings are di- or polyisocyanates and di- or polyhydroxy compounds. Active hydrogen-containing compounds, especially diols and diamines, as well as alkanolaraines, are also employed as chain extenders. In addition, various cross-linking agents such as neutral or tertiary amine based triols or tetrols are also used. 

Curene. [Anderson Development] Cross-linking agents, chain extenders urethanes, xies. 

Although foamed rubber and foamed urethanes have many similar properties, the processes by which they are made differ radically. In a simple process a solution of soap is added to natural rubber (NR) latex so that a froth will result on beating. Antioxidants, cross-linking agents, and a foam stabilizer are added as aqueous dispersions. 

Octabis(2-hydroxypropyl) sucrose A viscous, straw-colored liquid used as a cross-linking agent for urethane foams and as a plasticizer for cellulosics. 

This compound is not employed in urethanes. It is a cross-linking agent for adhesives and is used to increase bonding to rubber and plastic substrates and resistance to heat and solvents. 

As mentioned previously, the reaction injection-molding process combines two precisely metered and well-mixed reactive streams. An example is the process that reacts catalyzed highly reactive streams of urethane components. One stream contains a polyether backbone, a catalyst, and a cross-linking agent. The other stream has an isocyanate. In addition, a blowing agent is included in one of the streams. 

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