Masakatsu Ohguchi

Preparation of an acrylic-grafted polyester and its aqueous dispersion—Effect of the molecular structures of the grafted polyesters on viscosity and rheology of dispersion

An investigation was undertaken to develop a new class of water-borne polyesters that have various viscosity and various rheological profiles. We discussed the effect of the grafting condition on the molecular weights of the acrylic segments in the acrylic-grafted polyester. The molecular weights of the acrylic segments could be changed by an initiator concentration, a chain transfer agent concentration, and a monomer concentration. We discussed the viscosity and the rheology of the dispersions obtained from the above-grafted polyesters. The viscosity of the dispersion decreased as the molecular weights of the acrylic segments decreased. It was considered that the interaction between the particles of the dispersions decreased with a decrease in the thickness of the shell layer. The viscosity of the dispersions also decreased as the solubility of the acrylic segments in water decreased. It was considered that the interaction between the particle of dispersion decreased with the shrinkage of the shell layer. The rheological profile of dispersion was changed not by the molecular weights but the composition of the acrylic segments. The dispersions having various rheological profiles could be obtained by the control of the molecular weights or the composition of the acrylic segments in the grafted polyesters.

Preparation of an acrylics-grafted polyester and its aqueous dispersion

An investigation was undertaken to develop a new class of water-borne polyesters having excellent dispersibility without using emulsifiers. Grafting reactions of hydrophilic acrylics to polyesters and the relationships between reaction conditions and the dispersion diameters are discussed. Aqueous dispersions of particles having small diameters were obtained by use of an unsaturated polyester. Particle diameters were related to the grafting efficiency that could be enhanced by copolymerization of reactive monomers with the unsaturated bonds of polyesters. The relationships between particle diameters and the kind of acrylic monomers were described by the copolymerization reactivity ratio of the unsaturated polyester and acrylic monomers. Also, the influences of the solvency of the reaction medium and the influence of concentration of unsaturated bonds of the polyesters in the reaction medium were discussed to explain the low reactivity between the unsaturated bonds and acrylic monomers.

Preparation of an acrylic‐grafted polyester and its aqueous dispersion: Grafting utilizing alternating copolymerization

An investigation was undertaken to develop a new method to obtain fine dispersion of grafted polyester without gelation. As a new method, grafting utilizing alternating copolymerization of hydrophilic polymers to unsaturated polyester was discussed. By use of grafting utilizing alternating copolymerization, the reaction tendency of grafted polymer radical for an unsaturated bond of the polyester was changed. The grafting utilizing alternating copolymerization was compared with the conventional grafting, and the calculated grafting efficiency is about twice. Moreover, it was possible to increase the incorporation of less reactive monomers into the grafted side chain by the grafting utilizing alternating copolymerization. From the above results, the grafting utilizing alternating copolymerization is considered a useful method to prepare grafted polymers.

Preparation of an acrylics-grafted polyester and its aqueous dispersion—Structural study of acrylics-grafted polyesters

Structural study of two grafted polyesters, which were different in mechanical properties, was investigated by DMA, TEM, and high-resolution solid-state 13C-NMR. Using DMA and TEM, a separated phase larger than 100 nm was not found in the grafted polyesters. The main chain and the side chain seemed miscible. Analysis of T1ρHs and their distributions made the difference of microstructure in the grafted polyesters clear. P(EA-AA)-grafted polyester, which was very brittle, had a separated phase in the grafted polyester. The separated phase was estimated to be at a size of about 3 nm. On the other hand, P(St-DEF-MAnh)-grafted polyester, which was very ductile, had a homogeneous microstructure. The difference in the microstructures of the grafted polyesters seemed to effect the mechanical properties of the grafted polyesters.

Preparation of an acrylics-grafted polyester and its aqueous dispersion—mechanical properties of acrylics-grafted polyesters

Mechanical properties of grafted polyesters were discussed. In the case of grafting of acrylics of more than 25% in the grafting product, mechanical properties of the grafting products decreased greatly compared with the raw polyester. The influence of the molecular structure of the grafted polyester was not observed. The effect of composition of the grafted polymers was discussed. Mechanical properties varied with the composition of the side chain. In the case of grafting onto aromatic polyesters, grafting of an aromatic unsaturated monomer improved the mechanical properties of the grafted polymer. On the other hand, in the case of grafting onto an aliphatic polyester, grafting of an aliphatic unsaturated monomer improved mechanical properties of the grafting polymer. We found that the grafting of the polymer having a high compatibility with the polyester improved the mechanical properties of the grafting products, from the determination of the compatibility of each polymer and the mechanical properties of the grafting products.