Dulling agent

Using excess ethylene glycol is the usual practice because it drives the equilihrium to near completion and terminates the acid end groups. This results in a polymer with terminal -OH. When the free acid is used (esterification), the reaction is self catalyzed. However, an acid catalyst is used to compensate for the decrease in terephthalic acid as the esterification nears completion. In addition to the catalyst and terminator, other additives are used such as color improvers and dulling agents. For example, PET is delustred hy the addition of titanium dioxide. 

Another straightforward method to reduce the gloss consists in admixing a dull graft copolymer as dulling agent (33). Such copolymers may be prepared from n-butyl acrylate, allyl methacrylate, and hydroxypropyl methacrylate. Likewise, hydroxypropyl methacrylate may be substituted by maleic anhydride. The polymerization is started by 2,2 -azobi sisobu ty roni trile and peroxides. 

This material is a highly concentrated dulling agent making use of the dulling properties of titanium dioxide. The material exhibits some durability and may be used in relatively dilute solution to obtain satisfactory dulling. (1%-2%). 

EASTERN COLOR CHEMICAL CO. Dulling Agents(Continued) ... 

To illustrate this point consider the production of lacquers for PVC films and sheeting. Such lacquers contain a PVC homopolymer or low-acetate vinyl chloride-vinyl acetate copolymer, poly(methyl methacrylate), a plasticizer and perhaps some stabilizers, dulling agents (such as silica), pigments, and so on. Methyl ethyl ketone (MEK) is the solvent of choice because it gives the best balance of low toxicity, volatility, and low cost. Any other solvent is effectively... 

Crestodull M-3. [Reilly-Whiteman] Dulling agents for textiles. 

Emka Permadul. [Emkay] Dulling agents to nylon, rayon, acetate fabrics. 

Method of synthesis - caprolactam is melted and polymerized in the presence of catalyst and dulling agent ... 

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