INNER LINING FOR THE FOOTWEAR INDUSTRY
DESCRIPTION
The invention relates to an inner lining for the footwear industry and a process for its manufacture.
Wear resistant materials are used in the footwear industry for the lining of the inner part of the shoe, the so-called inner lining. Those materials are intended to support on the one hand the outward humidity transport by sweat generation at the foot, in order to guarantee a dry foot, and on the other hand distribute the forces generated during the rolling of movement onto large regions of the shoe leather, in order to thereby prevent the generation of folds and the faster wear associated therewith.
Thermally bonded and embossed calendared polyamide nonwovens were so far used for this purpose, napped or brushed nonwovens with textile appearance and soft hand, napped wovens, synthetic leathers on the basis of polyurethane coagulates or split leather of natural raw materials.
It is an object of the invention to provide an inner lining for the footwear industry, which at surface weights of 80 to 170 g/mz has initial tear strength and tear propagation strength in longitudinal and transverse direction > 7 N.
It is a further object of the invention to provide a process especially suited for the manufacture of such an inner lining.
This object is achieved in accordance with the invention with an inner lining which has surface weights of 80 to 170 g/m2 and a tear propagation strength in longitudinal and transverse direction > 7 N, whereby the inner lining is made of meltspun aerodynamically stretched mufti-component endless filaments immediately laid down into a nap with a titre of 1.5 to 5.0 dtex, the mufti-component endless filaments after a pre-consolidation being split to at least 80% into micro-endless filaments with a titre of 0.5 to 0.8 dtex, and then consolidated. These inner linings have high tension strength and wear resistance at low surface weights. Furthermore, because of the endless filaments, no edging is required with the inner lining in accordance with the invention and no fraying occurs and bulges in the seam region, and thereby possible pressure points, are avoided.
The inner lining is preferably one wherein the nonwoven consists of meltspun aerodynamically stretched mufti-component endless filaments immediately laid down into a nap and having a titre of 2 to 3 dtex, the mufti-component endless filaments possibly after a pre-consolidation being split to at least 80% into micro-endless filaments with a titre of 0.1 to 0.5 dtex and consolidated. The inner lining has an isotropic filament distribution in the nonwoven. It is therefore not necessary to take the machine direction into consideration during the cutting of the inner lining.
The inner lining is preferably one wherein the mufti-component endless filament is a bi-component endless filament of two incompatible polymers, especially a polyester (PES) and a polyamide (PA). The mufti-component endless filament has thereby a good splittability and a very advantageous ratio of strength to surface weight.
The inner lining is preferably one wherein the mufti-component endless filaments have a cross section with an orange type or "pie" mufti-segment structure, whereby the segments alternately include respectively one of the two incompatible polymers. Apart from this orange type mufti-segment structure of the mufti-component endless filaments, a "side-by-side" (s/s) segment arrangement of the incompatible polymers in the multi-component endless filament is also possible, which is preferably used for the generation of crimped filaments. Such segment arrangements of the incompatible polymers in the multi-component endless filament have proven to be very well splittable. The inner lining has a very advantageous ratio of surface weight to insulation capacity, so that a soft and warming inner lining can be manufactured, especially with downstream treatment steps such as napping.
The inner lining is definitely one wherein the nonwoven made of the multi-component endless filaments is pre-calendered for pre-consolidation. The material thereby has a very good thickness consistency.
A material with a textile appearance and a wear proof surface is further preferred as inner lining, which was obtained by treatment with high pressure water jets on a structured and/or open meshed sieve base.
Furthermore, an inner lining is especially preferred wherein at least one of the incompatible polymers forming the mufti-component endless filament includes an additive, such as colour pigments, permanently acting antistatics and/or additives which influence the hydrophilic or hydrophobic properties, in amounts of up to 15%
per weight.
The inner lining can thereby be positively influenced with respect to its light permanence, the propensity for static charging, the sweat transport or the humidity damming action.
The addition of the colour pigments into the extrusion mass furthermore enables the manufacture of deeper and wear resistant colours.
Furthermore, an inner lining is especially preferred wherein the mufti-component endless filament is uncrimped, since thereby the textile hand resulting from the good splittability into micro-endless filaments is guaranteed.
The inner lining is preferably one wherein one of the sides is coated with a hot melt adhesive coating. Such a material is especially suited for the further processing on automated machinery.
The process in accordance with the invention for the manufacture of the inner lining consists in that the mufti-component endless filaments are spun from the melt, aerodynamically stretched and immediately laid down into a nonwoven, an optional pre-consolidation by pre-calendering or needle punching is carried out and the nonwoven is consolidated by high pressure fluid jets and simultaneously split into micro-endless filaments with a titre of 0.1 to 0.8 dtex, preferably 0.1 to 0.5 dtex. The parts so obtained are very even with respect to their stability loading capacity, since a largely isotropic thread distribution is present in the product. The products show no tendency to de-lamination and have high module values and tear strength or tear propagation strength.
Furthermore, the inner linings in accordance with the invention have very good humidity transport properties which positively influence the comfort of the shoe provided therewith, with respect to the water vapour transport and the drying of wet shoes.
A further advantageous embodiment of the process consists in that the pre-consolidation and splitting of the mufti-component endless filaments is carried in that the possibly pre-consolidated nonwoven is subjected at least once from each side with high pressure water jets. This type of consolidation and spreading of the mufti-component endless filaments leads to very dense nonwovens with smooth surfaces.
The last high pressure water jet treatment is preferably carned out on a sieve base with mesh sizes of 5 to 50 mesh. The inner lining fabric is thereby additionally consolidated, becomes more wear resistant and is given a textile appearance.
Preferably, the impregnated material is subjected to downstream treatments such as dyeing, tumbling, grinding and/or sanforizing. The surface structure and hand of the material obtained can be further improved with these measues.
EXAMPLE
A filament nap with a surface weight of 110 g/mz is produced from a PES-PA-bi-component endless filament and is subjected alternately from both sides to a water jet needling at pressures of 280 bar. The water jet needling is thereby carned out in a total of four treatment passes, whereby the fourth passage is carried out on a 20 mesh sieve base.
A structured and/or perforated surface is thereby produced and the inner lining obtains a textile appearance and a soft hand. The water jet needling simultaneously achieves the splitting of the starting filaments to a titre < 0.2 dtex. The inner lining so produced is subjected to a jet dyeing and can be used without consideration to the machine direction.
The inner lining obtained has the stability perimeters listed in the following table and is well-suited for the indicated use.
Properties Unit Value Weight g/mz 110 Module 10% longitudinalN/5 cm 60 Module 10% transverseN/5 cm 40 Tear propagation N 8 strength longitudinal Tear propagation N 8 strength transverse Martindale (abrasionNote dry after 51,200good at rounds good 12 kPa) Note wet after 12,800 rounds