Cure catalyst effects

Curing Catalysts for A Methylol Agents. Many acid-type catalysts have been used in finishing formulations to produce a durable press finish. Catalyst selection must take into consideration not only achievement of the desked chemical reaction, but also such secondary effects as influence on dyes, effluent standards, formaldehyde release, discoloration of fabric, chlorine retention, and formation of odors. In much of the industry, the chemical suppher specifies a catalyst for the agent so the exact content of the catalyst may not be known by the finisher. 

Fig. 6. Influence of catalyst systems on cure rate effect of dimethylaniline (DMA) on cure rate of cast polymer resin at 25°C. Initiator system contains cobalt naphthenate (0.5%), MEKP (1.0%), and one of the following A, DMA (0.0%) B, DMA (0.05%) or C, DMA (0.1%).

Chlorine resistant to commercial launderings Excellent dry scorch resistance Excellent shrinkage control Excellent fabric smoothness Easily cured with magnesium cured catalyst Minimum effect on shade... 

Pendant Group on Acrylic or Methacrylic Polymer Reactive Monomer Containing Pendant Group Resin Co-reacted to Effect Cure Catalyst... 

BusSnOAc at I8O-85 BusSnCOAc) (5 0). (d) Use as catalyst for polyurethan preparation (229), relative activity as fungicide (I32O), (e) Use as curing catalyst for polyurethan rubber (559a). (f) Effect on complement... 

In this case, the components are mixed, the pH adjusted to about 6.0 with sodium hydroxide, and the solution appHed to the textile via a pad-dry-cure treatment. The combination of urea and formaldehyde given off from the THPC further strengthens the polymer and causes a limited amount of cross-linking to the fabric. The Na2HP04 not only acts as a catalyst, but also as an additional buffer for the system. Other weak bases also have been found to be effective. The presence of urea in any flame-retardant finish tends to reduce the amount of formaldehyde released during finishing. 

The relative effectiveness of nucleating agents in a polymer can be determined by measuring recrystallization exotherms of samples molded at different temperatures (105). The effect of catalyst concentration and filler content has been determined on unsaturated polyesters by using dynamic thermal techniques (124). Effects of formulation change on the heat of mbber vulcanization can be determined by dsc pressurized cells may be needed to reduce volatilization during the cure process (125). 

On curing, amino resins not only react with the nucleophilic sites (hydroxyl, carboxyl, amide) on the other film formers in the formulation, but also self-condense to some extent. Highly alkylated amino resins have less tendency to self-condense (33,34) and are therefore effective cross-linking agents, but may require the addition of a strong acid catalyst to obtain acceptable cure even at bake temperatures of 120—177°C. 

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