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EP-4281613-B1 - METHOD FOR PRODUCING 3D FIBER STRUCTURES

EP4281613B1EP 4281613 B1EP4281613 B1EP 4281613B1EP-4281613-B1

Inventors

  • ALIMADADI, Majid

Dates

Publication Date
20260513
Application Date
20220119

Claims (7)

  1. A method (100) for producing 3D fiber structures, the method (100) comprising: - feeding (101) a foamed fiber furnish (2) to an apparatus (1), the apparatus (1) comprising: - a liquid-permeable substrate means (3) having a first side (4) and an opposing second side (5); - a dispenser (6) having an outlet (7), wherein at least one of the dispenser (6) and the substrate means (3) travel with respect to the other; - dispensing (102), by means of the dispenser (6), a layer (2) of foamed fiber furnish to the first side of said liquid-permeable substrate means (3), so to obtain a fibrous mat, wherein the apparatus (1) further comprises at least a reservoir (8) and a first vacuum unit (9) associated with the second side (5) of the liquid-permeable substrate means (3) so to collect fluid discharge from the dispensed layer (2) of fibrous mat; - applying (103) at least a first dewatering pressure to at least a part of the second side (5) of said substrate means (3); wherein the layer (2) of fibrous mat is dispensed so to comprise a predefined substantially uniform thickness, wherein the apparatus (1) is configured to, preceding the step of applying (103) the first dewatering pressure: - by means of the reservoir, collect (104) fluid discharge for a first period of time based on at least the thickness of the layer (2); wherein the first dewatering pressure is applied for a second period of time, wherein the first dewatering pressure is within the range of 70 kPa - 100 kPa, wherein the first period of time is 1-10 minutes, wherein the second period of time is 2-10 minutes, wherein the thickness of the layer is within the range of 1-10 cm.
  2. The method (100) according to claim 1, wherein the liquid-permeable substrate means travels in a first direction along a length (L1) defined by at least a first and a second portion (15', 15"), wherein the dispenser (6) is arranged to be above the first side of the substrate means (3) in said first portion (15'), wherein the reservoir (8) is arranged in said first portion (15'), wherein the first vacuum unit (9) and a second vacuum unit (9') are arranged sequentially along the length (L1) in said second portion (15"), wherein the first vacuum unit (9) is closer to the reservoir (8) than the second vacuum unit (9').
  3. The method (100) according to claim 2, wherein the first vacuum unit (9) is configured to apply the e first dewatering pressure, wherein the second vacuum unit (9') is configured to apply a second dewatering pressure, wherein the first dewatering pressure is greater than the second dewatering pressure.
  4. The method (100) according to claim 3, wherein the second dewatering pressure is within a range of 50 kPa - 80 kPa.
  5. The method (100) according to any of the claims 1-4, wherein the method (100) further comprises the step of, preceding the step of applying the first dewatering pressure (103): - applying (105) an ultrasonic radiation towards the substrate means (3).
  6. The method (100) according to any one of the claims 2-5, wherein the method (100) is performed in a continuous process.
  7. The method (100) according to any one of the preceding claims, wherein the foamed fiber furnish comprises a fiber consistency in the range of 0.5-10% based on a dry weight of the fibers, wherein the foamed fiber furnish comprises a total concentration of foaming agents in the range of 0.05-2 g/l, wherein the foamed fiber furnish comprises an air content in the range of 55-70% by volume, wherein the foamed fiber furnish is generated from a pulp slurry.

Description

TECHNICAL FIELD The present disclosure relates to a method for producing 3D fiber structures. BACKGROUND ART Fiber network is an abundant structure among biological (e.g., animal tissues) and industrial materials which its characteristics is determined by individual elements' properties, orientation distribution, local and bulk density, bonding and entanglement between network elements. The morphology of many of biological fibrous structures are three-dimensional (3D) while manmade structures like paper and nonwoven are considered as two-dimensional (2D). In 3D fibrous structures, the constituent fibers are randomly oriented in the 3D space and the material bulk properties are distributed relatively uniform in all directions. In a 2D fibrous structure where constituent fibers are randomly oriented in the plane of the structure, in-plane bulk properties are drastically different compared to that of the normal direction to the plane. Unlike conventional paper, a 3D wood fiber structure is bulky, highly porous, and soft. These properties makes the 3D wood fiber structure a suitable candidate for applications related to absorption properties (shock, noise, moisture) and material transport properties (filtration). Industrial fibrous structures are made from synthesized or natural fibers using dry- or wet-laying processes where in the latter process, water is used as the carrier medium for the fibers. Alternatively, aqueous foam can be used as the suspending phase to obtain a 3D fiber network which with existing methods the procedure is energy-intensive and time-consuming and therefore it is industrially unfavorable. US3716449 A discloses forming of non-woven fibrous webs and in particular to the production of such webs utilizing a liquid suspending medium in the form of an aqueous foam in which the fibers are dispersed and suspended and from which they are formed into a layer on the wire of a paper-making machine, which layer is then collapsed and drained to form the web. US3542640 A discloses a method for drying a wet foam containing randomly dispersed fibers by drying the wet foam in a series of steps to produce low density, absorbent, fibrous paper or sponge-like material. The foam is deposited is deposited as a uniform sheet on a moving foraminous support where most of the water is removed by drainage. The remaining water in the foam is removed by phase change. Water removal by phase change may include one or the other or both of the steps of impinging a hot gas normal to at least one surface of the wet sheet and/or blowing a hot gas through the sheet. WO8805096 A1 discloses a method for the manufacture of very low density mineral wool structural panels on a moving foraminous support wire. A dilute aqueous furnish of mineral wool, lightweight aggregate, cooked wheat starch, cationic guar gum and non-ionic surfactant is formed, mixed to form a small amount of delicate non-resilient bubbles and ionically couple the mineral surfaces to the starch and gum, and deposited upon the wire to form an open, porous entangled mass which is rapidly stripped of water and dried in a flow-through configuration . Accordingly, there is a need for an improved method which satisfies the accelerated dewatering of the excess water from a foam-formed fibrous mat without deteriorating the bulk of the structure. SUMMARY It is therefore an object of the present disclosure to provide a method for producing 3D fiber structure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages. This object is achieved by means of a method as defined in the appended claims. In accordance with the invention there is provided a method according to claim 1. The present disclosure relates to a method for producing 3D fiber structures, preferably 3D wood fiber structures, the method comprising the steps of: Firstly, feeding a foamed fiber furnish to an apparatus, the apparatus comprising a liquid-permeable substrate means having a first side and an opposing second side, a dispenser having an outlet, wherein at least one of the dispenser and the substrate means travel with respect to the other. Further the method comprises the steps of: Dispensing, by means of the dispenser, a layer of foamed fiber furnish (or foamed wood fiber furnish) to the first side of said liquid-permeable substrate means to obtain a fibrous mat, wherein the apparatus further comprises at least a reservoir to facilitate an initial natural dewatering of the said fibrous mat for a predetermined time period, and a first vacuum unit associated with the second side of the liquid-permeable substrate means so to collect fluid discharge from the said fibrous mat. The method further comprises the step of applying at least a first dewatering pressure to at least a part of the second side of said substrate means. It should be noted that the foamed fiber furnish applied to the substrate means, takes the form of a fibrous mat. Thus, a layer of foamed