FIELD: process engineering.
SUBSTANCE: invention relates to articles from polymers, in particular, extruded threads, namely, flat thread extruded from synthetic raw stock with preset characteristics. Proposed flat thread comprises additives and consists of, at least, three layers. Note here that every layer features different properties while inner layer contains calcium carbonate. Note also that content of calcium carbonate makes 0.1-40 wt % of bulk raw stock of inner layer.
EFFECT: decreased abrasive properties, ruling out chalk dust, expanded applications.
