PURPOSE: To improve darkness, colored appearance, economics and easiness of preparation, by forming a pressure-sensitive adhesive layer of at least one layer wherein pigment-coated microbubbles are dispersed and incorporated in at least one layer on a flexible substrate.

CONSTITUTION: After non-coated microbubbles valve of glass and/or a polymer microbubbler (i), a pigment (ii) and at least two rods (iii) for mixing wherein each rod has a length being at least approximately the same as the inner diameter of a hollow cylindrical container and the total surface area of the rods are at least 5% of the inner surface area of the container, are placed in the hollow cylindrical container, the container is rotated for 3-15 min to obtain pigment-coated microbubbles (b) with a mean diameter of 5-200 μm coated with pigment-particle aggregate with a mean aggregate dimension of 0.5-5 μm. An acrylic pressure-sensitive adhesive layer (B) of at least one layer contg. 5-60 vol.% ingredient b in at least one layer comprising an acrylate (iv) of a non-tertiary alcohol with 1-14 C molecules, a polar copolymerizable monomer (v) and if necessary, a crosslinking agent (vi) (a) is formed on a flexible substrate (A).