Microprismatic retroreflective mold, sheet, and article and methods of manufacture thereof

A method, comprising:

• manufacturing an article, including:
• providing a substrate having a surface;
• forming a first set of first grooves in the surface, including moving a cutting tool through the surface in a repeating rising and diving motion along a first direction across the surface to form first zones of the first grooves with alternating dive sections and rise sections, wherein:
• the first grooves are parallel to each other along the same first direction across the surface,
• each of the first grooves include a repeating interleaved pattern of at least two first zones and at least two second zones, wherein a maximum depth ZT of the first zones is greater than a maximum depth ZS of the second zones, and
• each of the first zones of the first grooves include the rise section formed by the rising motion, the dive section formed by the diving motion, and a transition section located between the dive section and the rise section, wherein:
• the transition section entrance occurs at a depth equal to the maximum depth ZD2 of the dive section,
• the transition section exit occurs at a depth equal to the maximum depth ZR2 of the rise section, and
• the transition section includes a continuous surface transition between the dive section and the rise section to maintain surface continuity between the dive sections and rise sections without the presence of a seam, ridge, gap or tooling line;
• and
• forming a second set of second grooves in the surface, wherein:
• the second grooves are parallel to each other along a same second direction across the surface, the second direction being substantially perpendicular to the first direction such that an intersection of the first and second directions of the first and second grooves form an angle of 90±1 degrees, and
• the second grooves pass through the second zones of the first grooves, wherein a groove pattern is thereby formed on the surface, the groove pattern including microprisms.