Minnesota Mining and Manufacturing Company

Raymond E Grunzinger, Jr

Thomas R Borden

James H Harper

Louis C Belisle

A pavement marking material comprises a flexible base sheet that is conformable to an irregular pavement surface. A durable, wear-resistant, polymeric top layer is adhered to one surface of the base sheet. The top layer is capable of undergoing brittle fracture at a temperature from 0.degree. C. to 45.degree. C. such that when the base sheet conforms an irregular surface, the top layer readily forms ruptures to relieve stress build-up in the top layer as the regions of the top layer defined by the ruptures remain adhered to, and follow the conformance of, the base sheet. A plurality of particles are embedded in and protrude from the top layer. The particles comprise retroreflective beads and skid-resistant granules. In a preferred embodiment, the top layer is characterized by a Young's modulus of from about 50,000 psi to about 300,000 psi, and a percent elongation at break of from about 4% to about 35%.

Pavement marking material with rupturing top layer

The novel retroreflective sheeting has a flat transparent top coat which is as tough and as resistant to solvents and abrasion as are alkyd resins, and as weather resistant as are acrylic polyesters. That top coat is made from a mixture of hydroxy-functional acrylic polyol and a curing agent which is an aliphatic polyfunctional isocyanate such as the biuret of 1,6-hexamethylene diisocyanate. The retroreflective sheeting may have a dual-layer top coat, the outer layer being relatively hard to provide good resistance to solvents, abrasion and weathering, and the inner layer being softer to make the sheeting more conformable.

Flat transparent top coat for retroreflective sheeting

A retroreflective sheeting utilizing a particular polymer as the bead bond layer is disclosed. The polymeric bead bond comprises urethane and urea linkages, and has a stage prior to thermosetting in which it may be softened by the application of heat and in which it has a relatively nontacky character. The retroreflective sheeting disclosed possesses the unique combination of high reflectance and superior exterior durability.

Growing community of inventors

Saint Paul, MN, United States of America

Raymond E Grunzinger, Jr