Method for manufacturing lightweight foamed recycled leather and recycled leather produced by the method thereof

Abstract

A method of making a lightweight foamed recycled leather is described. The method includes pulverizing the collagen fiber waste generated in a controlling a thickness of the leather during a leather process; neutralizing the resultant of step (a) by a soda ash with a water; (c) dyeing and fat-liquoring process treating the resultant of the step (c); (d) mixing a latex, a dispersant, a coagulant, and a thermally expandable microspheres with the resultant of step (c); (e) coagulating a collagen fiber powder and the latex by adding a coagulant into the resultant of step (d); (f) dehydrating and drying the resultant of step (e); and (g) heat treating the resultant of step (f) to foam thermally expandable microspheres, thereby to impart functionality to the recycled leather.

Claims

1. A method of making a lightweight foamed recycled leather, wherein the method consists of the following steps in sequential order: (a) pulverizing the collagen fiber waste generated in a controlling a thickness of the leather during a leather process; (b) neutralizing the resultant of step (a) by a soda ash with a water for having the collagen fiber powder has a pH in a range of 6 to 7; (c) dyeing and fat-liquoring process treating the resultant of the step (b) for 10 to 120 minutes by adding 0.1 to 5% weight of a dye and 1 to 30% weight of a fat-liquoring agent with respect to a whole mixture; (d) mixing a latex, a dispersant, a defoaming agent, and a thermally expandable microspheres with the resultant of step (c); (e) coagulating a collagen fiber powder and the latex by adding a coagulant into the resultant of step (d); (f) dehydrating and drying the resultant of step (e); and (g) heat treating the resultant of step (f) to foam thermally expandable microspheres, thereby to impart functionality to the recycled leather, wherein the coagulant is Al.sub.2(SO.sub.4).sub.3 is in a range of 0.1 to 30% by weight, wherein the heat treating in step (g) is performed at 80-130 C.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Preferred embodiments of the present invention will be described in detail. In the following detailed description, exemplary embodiments of the present invention will be described in order to accomplish the above-mentioned technical problems. And other embodiments which may be presented by an embodiment of the present invention may be replaced by descriptions in the constitution of the present invention.

(2) According to aspect(s) of the present invention, a method of producing a lightweight foamed recycled leather is provided, which is environmentally friendly and lightweight is improved by using collagen fiber waste, which is one kind of leather waste generated during a leather-making process, in manufacturing recycled leather.

(3) Specifically, the present invention produces a lightweight foamed and regenerated leather while proceeding in steps (a) to (g) of the seven steps.

(4) In the step (a), the collagen fiber, which is a waste generated for controlling the thickness of the leather during a conventional tanning process, is pulverized using a conventional pulverizer.

(5) At this time, various scraps, textile scraps, fabric scraps, synthetic leather scraps, etc., which are generated in the production of shoe, may be used instead of the waste according to aspect(s) of the present invention.

(6) In step (b), the resultant product of step (a) is neutralized by treating with water and a soda ash a neutralizing agent. In step (c), the resultant product of step (b) processed for dyeing and fat-liquoring processes.

(7) At this time, the soda ash is used as the neutralizing agent, and neutralization of the pH of the acidic raw material suppresses an excessive coagulation during a latex treatment.

(8) In addition, the fat-liquoring process improves a flexibility of the recycled leather, and further promotes the dehydration during the production of the recycled leather, thereby improving the productivity.

(9) In step (d), a latex, a dispersant, an antifoaming agent, and a thermally expandable microsphere are mixed with the resultant product of the fat-liquoring process in the step (c).

(10) The latex is served as a binder for binding collagen fibers as a raw material. As the dispersing agent, a latex dispersing agent is used, and it plays a role of suppressing excessive coagulation of the latex.

(11) As an antifoaming agent, a general-purpose latex antifoaming agent is used, and the antifoaming agent is used to suppress bubbles which may occur during the latex treatment. The micro spares may serve to impart lightness to the recycled leather.

(12) In step (e), a coagulant is added to the resultant product of step (d) to coagulate the collagen fiber powder and the latex. In step (f), a vacuum dehydration and a roll press dehydration is performed to the resultant product of step (e), and then a hot air drying is performed for further dehydration of the resultant product of the step (e).

(13) At this time, in the vacuum dehydration process, dehydration is performed through a vacuum line to form a sheet when a mixed liquid, i.e., a mixed liquid of the collagen fiver powder and the latex, is distributed to the vacuum line after the latex coagulation process.

(14) In addition, after the vacuum dehydration process, the roll pressing is performed according to a thickness of the product produced by using a roll press in order to improve the binding force of the recycled leather and further reduce the remaining water content.

(15) The hot air dry process is performed in a drying chamber at a temperature of 70 to 110 C. for 4 to 6 minutes to dry the recycled leather.

(16) In a step (g), the resultant product of step (f) is heat treated at a high temperature, preferably 80 to 130 C., to foam thermally expandable microspheres to impart functionality, specifically, light weight of recycled leather, thereby the lightweight foamed recycled leather can be produced according to an aspect of the present invention.

(17) The temperature in a range of 80 to 130 C. is a minimum foaming temperature and an efficiency optimum temperature of the thermally expandable microspheres.

(18) The recycled leather produced by the above-mentioned method is used for various purposes such as shoes, industrial use, construction materials, and the like.

(19) Typical examples of the recycled leather are used for a sneaker upper and a safety shoes upper comfort shoes, bags, furniture materials, and the like.

(20) That is, it can be applied to all leather products requiring a light weight property.

(21) Hereinafter, aspect(s) of the present invention will be described in detail with reference to the preferred embodiments of the present invention, but the present invention is not limited thereto.

Example 1

(22) The collagen fiber waste generated in a tanning process is pulverized for 10 to 120 minutes and powdered, and then soda ash is treated in a mixing tank so that the collagen fiber powder has a pH of 6 to 7.

(23) At this time, the pH of the collagen fiber powder is adjusted to 6 to 7 in order to prevent excessive coagulation during a latex treatment.

(24) After the latex treatment, 0.1 to 5% by weight of a dye and 1 to 30% by weight of a fat-liquoring agent are performed with respect to a whole mixture, and then a dyeing and fat-liquoring process for 10 to 120 minutes for a beautiful color and flexibility.

(25) Next, 10 to 50% by weight of latex as a bonding material, 1 to 10% by weight of a dispersant, a defoaming agent and a thermo-expandable microsphere are mixed in an amount of 1 to 30% by weight based on the raw material content,

(26) 0.1 to 30% by weight of Al.sub.2 (SO.sub.4).sub.3, which is a coagulant, is coagulated, and the mixture is formed into a sheet, followed by vacuum, compression, dehydration, and drying to produce a recycled leather sheet.

(27) Thereafter, the recycled leather is foamed through a heat treatment at 80 to 130 C. to produce a leather product.

(28) The leather produced according to the process of example 1 described above can be used as a material for a footwear such as a sneaker upper or a safety shoes upper, or as a bag material, and is not limited to a material for manufacturing a specific product.

Comparative Example 1

(29) Except that the functional microspheres were not treated, and all of the steps and products may be the same conditions except for the post-drying heat treatment step to produce recycled leather.

(30) Meanwhile, according to an aspect of the present invention, evaluation of the physical properties of recycled leather produced by treating thermally expandable microspheres was carried out, as shown in Table 1 below.

(31) The properties of the recycled leather prepared according to the examples and comparative examples were prepared as shown in Table 1 below, and specific gravities and light weight properties of each sample were analyzed.

(32) The results of the measurements are shown in Table 1.

(33) At this time, the light weight property is a weight reduction ratio for the comparative example of the conventional recycled leather.

(34) TABLE-US-00001 TABLE 1 Classification Example 1 Comparative example weight 0.14 0.58 Light weight property (%) 76 0