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CN-122013445-A - Hollow three-dimensional gradient needling process

CN122013445ACN 122013445 ACN122013445 ACN 122013445ACN-122013445-A

Abstract

The invention discloses a hollow three-dimensional gradient needling process, which adopts a sparse needle plate, a1 st needling machine pierces the upper surface layer and the lower surface layer of a fiber web to carry out preliminary entanglement shaping, adopts a dense needle plate, and a2 nd to 6 th needling machines respectively carry out needling on the upper surface layer and the lower surface layer of the fiber web, wherein the needling depth is controlled within the range of 1/3 to 2/3 of the thickness of the fiber web, so that the needling only penetrates through a core layer and the surface layer on the corresponding side but not penetrates through the opposite side surface layer to form a gradient structure with the preliminary dense core layer of the surface layer, and adopts the dense needle plate, and a 7 th to 9 th needling machine only carries out encryption needling on the upper surface layer and the lower surface layer of the fiber web without piercing the core layer, wherein the needling depth is controlled at the 1/3 of the thickness of the fiber web to ensure that the surface layer fibers form a rigid supporting layer with high-density entanglement, and the hollow structure of the core layer fibers is reserved. By needling in stages, a gradient structure with loose surface compact core layer is constructed in the thickness direction, so that the surface strength is ensured, the hollow structure of the core layer fiber is reserved, and the material is light, high in rebound, high in strength and durable in long-acting.

Inventors

  • ZHANG WANFENG
  • ZHANG PENG
  • CAO WEINAN
  • CHEN HUANGJIE

Assignees

  • 安安(中国)有限公司

Dates

Publication Date
20260512
Application Date
20260227

Claims (9)

  1. 1. A hollow three-dimensional gradient needling process is characterized by comprising the following steps: A pre-needling step, namely pre-needling the fiber web by adopting a drainage needle plate and a fine needling needle, wherein the fiber web sequentially comprises an upper surface layer, a core layer and a lower surface layer, and a 1 st needling machine pierces the upper surface layer and the lower surface layer of the fiber web to enable the fiber web to be preliminarily entangled and shaped, and the hollow structure of the core layer fiber is reserved; a main needling step, namely needling the upper surface layer and the lower surface layer of the fiber net by adopting a densely arranged needle plate and a 2-6 needling machine respectively, wherein the needling depth is controlled within the range of 1/3 to 2/3 of the thickness of the fiber net, so that the needling only penetrates through the core layer and the surface layer at the corresponding side, but does not penetrate through the surface layer at the opposite side, and a gradient structure with preliminary compactness of the surface layer and loose core layer is formed; The surface layer encryption step is to adopt a close-packed needle plate and thick needles, and the 7 th to 9 th needling machines only encrypt and needle the upper surface layer and the lower surface layer of the fiber net without piercing the core layer, and the needling depth is controlled at 1/3 of the thickness of the fiber net, so that the surface layer fibers form a rigid supporting layer with high-density entanglement, and the hollow structure of the core layer fibers is reserved.
  2. 2. The hollow three-dimensional gradient needling process according to claim 1, wherein in the pre-needling step, a needle plate with a needle pitch of 4-6mm is adopted, a 42-44-gauge fine needle is matched, the needling density is 80-120 needling/cm <2 >, the vehicle speed is 8-10m/min, and the needling frequency is 800-1000 times/min.
  3. 3. The hollow three-dimensional gradient needling process according to claim 2, wherein in the main needling step, a closely-spaced needle plate with a needle pitch of 2-3mm is adopted, needling density is 180-220 needling/cm < 2 >, vehicle speed is 6-8m/min, needling frequency is 1350-1750 times/min, and needle penetration angle is 90+ -2 °.
  4. 4. The hollow three-dimensional gradient needling process according to claim 3, wherein in the surface layer encryption step, a closely-spaced needle plate with a needle pitch of 2-3mm is adopted, 38-40-size coarse needles are matched, needling density is 300-400 thorns/cm < 2 >, vehicle speed is 4-6m/min, and needling frequency is 1200-1500 times/min.
  5. 5. The process according to any one of claims 1 to 4, wherein the hollow percentage of the core layer is maintained at 70% or more after the pre-needling step, and the hollow percentage of the fiber web core layer is maintained between 30% and 50% after the main needling step and the skin encryption step.
  6. 6. The process of claim 5, wherein in the main needling step, only the upper surface layer and the core layer are pierced when needling is performed, and only the lower surface layer and the core layer are pierced when needling is performed, so that a symmetrical gradient structure is formed.
  7. 7. The process of claim 1, wherein the fiber web is made of sea-island fiber, the sea-island fiber is made of a COPET as a sea component and PA as an island component, and the superfine sea-island fiber is made by a composite spinning technology by adding color master batches.
  8. 8. The three-dimensional gradient needling process of claim 1, wherein the pre-needling step is preceded by: The opening step is that the fiber raw material is processed by 3-4 opening procedures, the opening degree is controlled to be more than or equal to 95 percent, and the fiber agglomeration rate is controlled to be less than or equal to 0.5 percent; carding and lapping, namely carding the opened fibers into a thin net with the single gram weight of 50-60g/m < 2>, lapping the thin net according to 8-10 layers, controlling the total gram weight to be 400-500g/m < 2>, and prepressing the thin net by a light press roller under the pressure of 0.5-1MPa after lapping.
  9. 9. The hollow three-dimensional gradient needling process according to claim 8, wherein the orientation ratio of the longitudinal fibers to the transverse fibers is 1 (1.1-1.2) in the lapping process, and the gram weight uniformity is controlled within minus or plus (5-10)%.

Description

Hollow three-dimensional gradient needling process Technical Field The invention relates to the technical field of synthetic leather, in particular to a hollow three-dimensional gradient needling process, which realizes a high-elasticity lightweight preparation method and is suitable for scenes with high requirements on elasticity, lightweight and high performance, such as shoe materials, clothes, automobile interiors and the like. Background The superfine fiber synthetic leather (microfiber leather) is widely applied to the fields of shoe materials, clothes, automobile interiors and the like due to the excellent mechanical properties and imitation leather hand feeling. The traditional microfiber leather adopts solid fibers (such as conventional PET and PA fibers) as a base material, is subjected to single-density needling reinforcement through a flat needling machine after carding to form a nonwoven fabric framework with uniform entanglement among fibers and compact structure, and is prepared into a finished product through the procedures of polyurethane impregnation, fiber opening, post finishing and the like. However, the conventional needling process has the following technical drawbacks: 1. The uniform structure results in light weight and high elasticity, and the conventional needling process adopts uniform needling density and needling depth to form a structure with uniform density in the thickness direction of the fiber web. In order to ensure the strength of the material, a higher needling density (250-350 thorns/cm < 2 >) is generally required, so that the material density is higher (more than or equal to 0.55g/cm < 3 >), and the light weight requirements of the fields of shoe materials, automobile interiors and the like are difficult to meet. If the needling density is reduced to pursue weight reduction, fiber entanglement is insufficient, the material strength is remarkably reduced (tensile strength is less than or equal to 5 MPa), and the use requirement cannot be met. 2. The hollow structure of the core layer is destroyed, and in order to realize light weight, partial researches are attempted to adopt hollow fibers as raw materials. However, in the conventional needling process, the needles completely penetrate through the full thickness of the fiber web, the core fibers are densely entangled and compressed by repeated needling, the cavity structure of the hollow fibers is crushed or filled, the hollow rate is reduced from 40-60% of the raw materials to less than or equal to 30% of the finished product, and the light weight effect is greatly reduced. 3. The fatigue life is insufficient under dynamic load, namely, the shoe material repeatedly bears compression-rebound cycles under dynamic load such as running, jumping and the like. The traditional homogeneous structure is lack of gradient buffer layer, stress is concentrated on fiber winding nodes, and microcrack expansion is easy to occur. Tests show that after 10 ten thousand times of dynamic bending, the tensile strength attenuation rate of the traditional microfiber leather reaches 45 percent, the tearing strength attenuation rate exceeds 30 percent, and the requirements of high-end shoe materials on durability are difficult to meet. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a hollow three-dimensional gradient needling process, and a gradient structure of 'surface layer compactness-core layer looseness' is constructed in the thickness direction by stage needling, so that the surface layer strength is ensured, the hollow structure of core layer fibers is reserved, the light weight, high rebound, high strength and long-acting durability of the material are realized, and an advanced material solution which takes both performance and light weight into consideration is provided for the fields of shoe materials, clothing, automobile interiors and the like. In order to achieve the purpose, the invention is realized by the following technical scheme that the hollow three-dimensional gradient needling process comprises the following steps: A pre-needling step, namely pre-needling the fiber web by adopting a drainage needle plate and a fine needling needle, wherein the fiber web sequentially comprises an upper surface layer, a core layer and a lower surface layer, and a 1 st needling machine pierces the upper surface layer and the lower surface layer of the fiber web to enable the fiber web to be preliminarily entangled and shaped, and the hollow structure of the core layer fiber is reserved; a main needling step, namely needling the upper surface layer and the lower surface layer of the fiber net by adopting a densely arranged needle plate and a 2-6 needling machine respectively, wherein the needling depth is controlled within the range of 1/3 to 2/3 of the thickness of the fiber net, so that the needling only penetrates through the core layer and the surface layer at the corresponding side, but does not