Non-woven filtration material and air cleaner element

A non-woven filtration material comprising a multilayer structure having a density gradient, wherein

• the multilayer structure includes a coarse layer disposed at an upstream side of the non-woven filtration material and a dense layer disposed at a downstream side of the non-woven filtration material, bulk density of the coarse layer being lower than bulk density of the dense layer,
• the coarse layer and the dense layer are dry layers that are substantially neither impregnated nor coated with oil,
• the coarse layer contains 30% to 60% by weight of crimped conjugated fibers and contains 30% to 70% by weight of finer fibers,
• the crimped conjugated fibers have an average fiber diameter in a range from 15 μm to 45 μm,
• the finer fibers have an average fiber diameter that is in a range from 5 μm to 20 μm and smaller than the average fiber diameter of the crimped conjugated fibers,
• the crimped conjugated fibers have a coil-shaped or spiral-shaped three-dimensional structure in the coarse layer, and
• the crimped conjugated fibers and finer fibers are intermingled with each other and three-dimensionally arranged in the coarse layer.