Hybrid dispersion Crosslinking

Designation of hybrid Dispersion Crosslinking of Acrylic/ styrene Properties of dispersions ... 

Designation of Hybrid Dispersion Crosslinking of Acrylic/styrene part of hybrid Properties of films ... 

The properties of hybrid dispersions prepared using method la (see Section 6.3.2), having the same chemical composition and differing only in the presence or absence of partial crosslinking of the acrylic/styrene polymer component are presented in Tables 62.7 to 6.29. Dispersions contained 3.3% of NMP. 

Table 6.27 Properties of hybrid dispersions differing only in the presence or absence of crosslinking of the acrylic/styrene part of the hybrid ... 

Table 6.29 Results of investigation of degree of crosslinking of hybrid dispersions using the equilibrium swelling test. Results obtained for the starting ...

Designation of hybrid dispersion Designation of starting dispersion Method of hybrid synthesis a max % Soluble fraction, S, % Crosslinking density, j Fraction of active chains. Vs... 

S.4.4 Investigation of the Effect of the Method of Synthesis of Hybrid Dispersions on their Degree of Crosslinking... 

Table 6X7 shows that the properties of hybrid dispersions prepared with additional crosslinking of acrylic/styrene polymer do not differ from the properties of dispersions of the same composition prepared without additional crosslinking. Also the properties of films made from both dispersions were very similar (see Table 6.28). However, lack of positive effects of additional crosslinking of the acrylic/styrene part of the hybrid may result from improper selection of starting materials for hybrid synthesis. Therefore, we intend to investigate this effect further in another study along with further studies on the effect of introducing double bonds to the polyurethane-urea part of the hybrid.

Figure 6.34 Schematically presented embedded sphere morphology of the particles of hybrid dispersions prepared according to method 2 (diluting the prepolymer-ionomer with monomers, emulsifying it in water, crosslinking with polyamine and polymerisation)...

For printing inks that require specific properties not obtainable by conventional styrene acrylic emulsions, an aqueous dispersion of an add functional polyurethane-epoxy acrylate hybrid (self crosslinking for improved chemical resistance) [9] patented by Air Products and Chemicals, Inc. or a self crossHnking styrene acrylic emulsion which reacts upon evaporation of water [10] patented by Akzo Nobel Resins BV, may be used. The Air Products novel dispersion contains a quaternary ammonium polyurethane acrylic hybrid carboxylate salt and pendant acrylate epoxide that selfcrosslink upon evaporation of water and ammonia. Akzo s novel polymer contains a diacetone acrylamide reactive monomer and a bishydrazide. The crossHnking reaction between ketone groups and a bishydrazide proceeds rapidly at room temperature, after evaporation of water from the ink. 

The degree of crosslinking of the starting dispersions (DPUR and ASD) and the hybrids was determined nsing the equilibrium swelling test described in Section 4.3. The following parameters were calculated based on the results of this experiment ... 

Another hybrid system has been proposed for resist applications the simultaneous chain polymerization of N-methylolacrylamide and the acid-catalyzed crosslinking of the resulting polymer with poly(vinyl alcohol) In dual cure plastisols, finally, a solid thermoplastic resin is dispersed in a multifunctional aciyrlate mixture which contains a thermal and a photoinitiator. These plastisols have been proposed for the encapsulation of integrated circuits... 

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