AbstractA previously reported synthetic procedure was used to graft oligo‐p‐hydroxybenzoic acid (oligo‐PHBA) to COOH‐functional acrylic copolymers. Most of the products were side‐chain LC copolymers. Length of the mesogenic oligo‐PHBA groups averaged up to five aromatic rings per group. Because these long mesogenic groups have a strong tendency to form LC domains, it was possible to prepare LC side‐chain copolymers having as little as 5 mol of mesogenic monomer. Thus this synthetic procedure provides a versatile route for exploration of the properties of LC copolymers having relatively few but especially effective mesogenic groups. The potential utility of such LC copolymers as binders for nonbake coatings was assessed. Variables studied were molecular weight andTgof the acrylic copolymer backbone, number and average length of oligo‐PHBA segments, and the presence or absence of a flexible spacer between the acrylic backbone and the PHBA segments. Optimum LC copolymers have moderate (15,000–30,000)Mn, low (−10°C) backboneTg, and low (5–7.5 mol ) population of long (5 PHBA units) oligo‐PHBA units. Such copolymers have two major advantages as coatings binders: They form concentrated, stable, low‐viscosity dispersions in common solvents, a very desirable characteristic for application. Coating films have excellent adhesion to metal, and they have an extraordinary combination of hardness (H–2H) and impact resistance (>80 in. Ib). These properties are key indicators of coating performance and indicate that LC copolymers have excellent potential for use as binders for nonbake coatings. Other properti
展开▼
