| 摘要 |
1,211,027. Moulding reflective articles. MINNESOTA MINING & MFG. CO. 13 Nov., 1967 [14 Nov., 1966 (2)], No. 51615/67. Heading B5A. [Also in Division [G2] A transparent, plastics retro-reflector 10a, Fig. 2, of e.g. polystyrene, has prismatic cube corner reflecting units 11a embossed on its rear surface, and septa 13a divide the surface into polygonal cells, e.g. rectangular cells as shown, or triangular cells (Fig. 1, not shown), each cell containing a plurality of cube corner units. A rigid or flexible backing (16, Fig. 3, not shown) is bonded by heat sealing or adhesives to the free ends at the septa 12a, 13a and the void between the reflector 10a and the backing (16) may be filled with a particulate material (17, Fig. 3, not shown) of e.g. glass bubbles, for strengthening. A multiplicity of reflectors 10a may be bonded to a flexible backing web (21, Fig. 5, not shown) which may be folded or rolled up and the web may be cut to form letters for road signs. The reflectors are formed by compression moulding or injection moulding, in apparatus (Fig. 15, not shown) having a die (30, Fig. 6, not shown) comprising a matrix of four types of hexagonal section pins (32, 37, 44, 51, Figs. 7-14, not shown) each pin being formed at one end with three square plane facets joined at right angles. Pins (37, 44, 51) are formed with notches, which on assembly of the pins into the matrix, are interconnected to form continuous slots across the face of the die, dividing the die into sections. In a second embodiment (Figs. 18-23, not shown) the die is formed of four types of square-section pins with the squared-off ends of the pins staggered a distance equal to the pin thickness, and with the longitudinal axis of the pins on a slant. Three of the types of pins have notches for forming the septa in the reflectors. In a third embodiment (120, Fig. 26, not shown) the die is formed of sawtooth-edged plate-like elements (121). |
