Hybrid dispersion Properties

Method of Synthesis Designation of hybrid dispersion Properties of dispersions ... 

If a comparison were made between hybrid dispersion systems taking into account the kind of dispersion particles they contain, it would appear that the best properties should generally be observed for systems obtained by synthesis for which the particles have a uniform structure (they may be called true hybrid particles) and the worst - for simple blends of the two dispersions [14] (see Figure 6.1). 

A recently published patent [33] from Zeneca described in detail the methods of preparation of hybrid polyurethane/vinyl polymer dispersions but neither discussed the effect of various factors on the properties of the hybrid dispersions nor provided any information on their particle morphology. 

Investigation of the Effect of Various Factors on the Properties of Hybrid Dispersions... 

The results of investigations of the effect of method of hybrid dispersion synthesis (la, lb, 2 or 3 - see Section 3.2) on the properties of dispersions as well as of films and coatings made from them are presented in Tables 6.9 to 6.11 (dispersions prepared using water-soluble initiator) and in Tables 6.12 to 6.14 (dispersions prepared using redox initiating system). In all dispersions the chemical structure of the polyurethane-urea and acrylic/styrene polymer component was the same (see relevant tables in Section 6.5.2). All the dispersions contained a similar low level (2-3.6%) of NMP. 

Table 6.9 Properties of hybrid dispersions of the same chemical composition prepared according to different methods using a water-soluble initiator (K S O ) ... 

In Tables 6.18 to 6.20 the properties of two hybrid dispersions prepared using the same method la (see Section 3.2) and having the same structure of the acrylic/styrene part of the hybrid but based on different polyols, as well as of films and coatings made from them are presented. Neither dispersion contained coalescent (NMP)... 

Properties of hybrid dispersions prepared according to the different methods (la, lb and 2 - see Section 6.3.2) and based on the same polyol (PTMG 2000), but differing in the presence or absence of double bonds in the polyurethane-urea part of the hybrid, as well as of films and coatings made of them, are presented in Tables 6.21 and 6.22. All dispersions have a similar low level (2.0-3.3%) of coalescent and have the same structure of the acrylic/styrene part of the hybrid. Redox initiator was used in the synthesis of dispersions according to the method 2, and in all other dispersions presented in these tables a water-soluble initiator was applied. 

Table 6.18 Properties of hybrid dispersions differing only in the structure of the polyurethane-urea part of the hybrid ...

Designation of hybrid Dispersion Polyol Properties of coatings ... 

Table 6.22 Properties of films made from hybrid dispersions differing only in the presence of double bonds...

The properties of hybrid dispersion prepared according to two different methods (la and 3 - see Section 3.2) and having the same chemical composition and differing only in the chemical structure of the acrylic/styrene polymer component are presented in Tables 6.24 to 6.26. All dispersions were synthesised using a water-soluble initiator. Dispersions prepared according to method la did not contain any coalescent while dispersions prepared according to method 3 contained 11.6% of NMP. 

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