Environment-friendly regenerated leather and preparation method thereof

Abstract

The invention discloses environment-friendly regenerated leather and a preparation method thereof. The preparation method comprises the following steps: fibration treatment; forming a net by a wet method; compounding with sea-island fibers; performing high-pressure spunlace entanglement; performing drying treatment; and surface treatment. Through the process design of wet laying, compounding with sea-island fibers and high-pressure spunlace entanglement, the interlayer bonding strength of the regenerated leather is effectively improved, and the interlayer stripping resistance is improved; the preparation process is green and environment-friendly, and the prepared leather is soft in leather, excellent in air permeability and high in tensile strength and has the effect of genuine leather.

Description

Technical Field

[0001] The present invention relates to the technical field of leather preparation, and particularly to an environmentally friendly regenerated leather and a preparation method thereof. Background Art

[0002] With the development of the economy and the improvement of people's living standards, leather products are widely used in people's daily lives due to their high aesthetic value and good texture, such as being widely used in many fields such as clothing, footwear, home furnishings, automobiles, and public services.

[0003] As is well known, a large amount of natural leather scraps are generated during the production of leather products. If these scraps are not effectively utilized, it will cause serious waste of resources and environmental and ecological pollution. The traditional treatment method is to crush animal leather scraps and then add chemical raw materials for mixing and reprocessing into imitation leather. This kind of synthetic leather has rough workmanship, poor tensile resistance and air permeability.

[0004] Chinese Patent CN 112644104A discloses an imitation leather, an imitation leather base fabric and a manufacturing method thereof. This method can solve the problem of rough synthetic leather process existing in the traditional process. However, the applicant found during the implementation of the technical solution of the present invention that its preparation process needs to rely on the treatment with sodium hydroxide solution to remove the "sea" part, the process is complex, and there is chemical pollution. The interlayer peeling strength of the prepared imitation leather still needs to be improved. Summary of the Invention

[0005] The present invention provides an environmentally friendly regenerated leather and a preparation method thereof, which solves the problems of resource waste and poor performance of regenerated products caused by improper treatment or utilization method of leather scraps during the production process of existing leather preparation.

[0006] To solve the above technical problems, the present invention provides a preparation method of an environmentally friendly regenerated leather, including the following steps:

[0007] (1) Fibrosis treatment: Collect animal leather scraps and perform fibrosis treatment to obtain corresponding fibers;

[0008] (2) Wet laying: Wet lay the obtained fibers to obtain a fiber cloth;

[0009] (3) Composite with sea-island fiber: Uniformly spread sea-island fiber on one side surface of the fiber cloth to form a sea-island layer. After preliminary lamination in a negative pressure adsorption device, perform pre-entanglement with low-pressure hydroentanglement at 5-10 MPa to form a composite layer;

[0010] (4) High-pressure hydroentanglement: Perform positive stabbing, reverse stabbing and bidirectional alternating diagonal stabbing on the composite layer in step (3) in sequence with gradient high-pressure hydroentanglement to achieve three-dimensional entanglement of the composite layer, where:

[0011] The positive water jet pressure is 25 - 30 MPa, from the side of the fiber cloth to the side of the sea-island layer;

[0012] The reverse water jet pressure is 30 - 40 MPa, from the side of the sea-island layer to the side of the fiber cloth;

[0013] The bidirectional alternating diagonal water jet pressure is 40 - 50 MPa;

[0014] (5) Drying treatment: The composite layer after high-pressure water jet entanglement is dried and shaped in a drying oven;

[0015] (6) Surface treatment: After drying, the surface of the sea-island layer is ground and fluffed to obtain the environmentally friendly recycled leather.

[0016] In a preferred embodiment of the present invention, in step (1), the method of fibrillation treatment is as follows:

[0017] First, the collected animal skin scraps are softened by treatment with neutral protease, and then the softened leather is pretreated with high-pressure water jet at 20 - 30 MPa to obtain corresponding fibers, and fiber modification treatment is carried out.

[0018] In a preferred embodiment of the present invention, the method of fiber modification treatment is as follows: First, it is impregnated in a chitosan acetate solution with a mass concentration of 2 - 5% and a pH value of 4 - 5 for 1 - 2 h. After taking it out and squeezing out the impregnating solution, a nanofibrillated cellulose suspension with a mass concentration of 1 - 3% is then sprayed.

[0019] In a preferred embodiment of the present invention, 0.3 - 0.8% of a biosurfactant is added to the water jet liquid of the high-pressure water jet.

[0020] In a preferred embodiment of the present invention, in step (2), the grammage of the fiber cloth is 80 - 150 g / m 2 .

[0021] In a preferred embodiment of the present invention, in step (3), the vacuum degree of the negative pressure is -0.05 - -0.08 MPa; the pressure of the low-pressure water jet is 5 - 10 MPa.

[0022] In a preferred embodiment of the present invention, in step (3), in the composite layer, the thickness ratio of the fiber cloth to the sea-island layer is 1:2 to 1:3.

[0023] In a preferred embodiment of the present invention, in step (4), the angle of the bidirectional alternating diagonal water jet is 40 - 60°; the entanglement degree of the fibers after three-dimensional entanglement is ≥85%.

[0024] In a preferred embodiment of the present invention, in step (5), the process conditions for drying and shaping are as follows: first, dry for 1 - 3 minutes under the condition of 100 - 105 °C, then dry for 2 - 5 minutes under the condition of 80 - 90 °C, and finally dry for 1 - 3 minutes under the condition of 65 - 70 °C.

[0025] To solve the above technical problems, the present invention provides an environmentally friendly regenerated leather, which is prepared by the above method. The environmentally friendly regenerated leather includes a bovine fiber layer and a sea-island fiber layer, wherein the mass ratio of bovine fiber to sea-island fiber is 1:1 - 1:2.

[0026] The beneficial effects of the present invention are as follows: The preparation method of an environmentally friendly regenerated leather of the present invention effectively improves the interlayer bonding strength of the regenerated leather and enhances the interlayer peeling resistance through the process design of wet laying, compounding with sea-island fibers, and high-pressure hydroentanglement; the preparation process of the present invention is green and environmentally friendly, and the prepared leather has soft texture, excellent air permeability, high tensile strength, and the efficacy of genuine leather. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a process flow schematic diagram of the preparation method of an environmentally friendly regenerated leather of the present invention;

[0028] Figure 2 is a structural schematic diagram of the environmentally friendly regenerated leather prepared in Example 1 of the present invention;

[0029] The marks of each component in the drawings are as follows: 10. Fiber cloth, 20. Sea-island layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following elaborates on the preferred embodiments of the present invention with reference to the drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0031] Please refer to Figure 1 and 2 , the embodiments of the present invention include:

[0032] Example 1

[0033] The present invention discloses a preparation method of an environmentally friendly regenerated leather, using waste leather scraps as raw materials, and the specific steps are as follows:

[0034] (1) Fibrosis treatment: Collect waste leather scraps, clean them, cut them into small pieces of 5 - 10 mm, and soak the above-mentioned small leather pieces in trypsin under the conditions of pH value of 6.5 and temperature of 40 °C for 2 hours to soften them and reduce the difficulty of fiber separation.

[0035] Then, the softened cowhide is pretreated by high-pressure hydroentangling at 25 MPa with 0.5 wt% sophorolipid added to reduce the surface tension of the cowhide fibers and obtain cowhide fibers.

[0036] The obtained cowhide fibers are first impregnated in a 3 wt% chitosan acetate solution with a pH value of 4.5 for 1 h to enhance the subsequent binding force between the cowhide fibers and the sea-island fibers.

[0037] After squeezing out 95% of the impregnating liquid from the cowhide fibers, a 2% nanocellulose suspension (with a particle size of 50 nm) is evenly sprayed to increase the interfacial friction coefficient of the cowhide fibers.

[0038] (2) Wet laying: The obtained cowhide fibers are soaked in warm water at 45 °C with 0.5% TX-100 added at a solid-liquid ratio of 1:40 for 30 minutes to reduce the surface energy of the fibers.

[0039] Then, they are mixed in a dispersion with a pH value of 7 and 0.1% polyethylene oxide added at a proportion of 0.5 wt% of the cowhide fiber content, and dispersed and stirred at a speed of 2500 r / min for 20 min using a high-speed shear machine to prepare a suspension.

[0040] The obtained suspension flows through an inclined screen former with a screen curtain mesh number of 80 at a speed of 1.0 m / min and is vacuum dehydrated to a moisture content of 70% to obtain a fiber cloth 10 with a grammage of 100 g / m 2 ².

[0041] (3) Composite with sea-island fibers: Sea-island fibers are evenly spread on the upper surface of the fiber cloth prepared above and transported into a negative pressure adsorption device at -0.05 MPa, so that the sea-island fibers are initially attached to the fiber cloth to form a sea-island layer 20. The spreading amount of the sea-island fibers is controlled such that the thickness ratio of the fiber cloth to the sea-island layer is 1:3. Then, 10 MPa low-pressure hydroentangling is used for pre-tangling to form a composite layer and a "barbed" mechanical anchoring structure is formed between the fibers to enhance the interlayer bonding strength.

[0042] (4) High-pressure hydroentangling: The composite layer in step (3) is successively subjected to forward piercing, reverse piercing, and bidirectional alternating diagonal piercing treatments using 25 - 50 MPa high-pressure hydroentangling to achieve three-dimensional entanglement.

[0043] Specifically, the water pressure of the forward piercing, reverse piercing, and bidirectional alternating diagonal piercing increases in a gradient;

[0044] For the forward piercing, the water pressure is 30 MPa, from one side of the fiber cloth 10 to one side of the sea-island layer 20;

[0045] For the reverse piercing, the water pressure is 35 MPa, from one side of the sea-island layer 20 to one side of the fiber cloth 10;

[0046] The bidirectional alternating diagonal piercing is carried out at a water pressure of 40 MPa, with a diagonal piercing angle of 45°, and bidirectional penetration is achieved.

[0047] The number of hydroentangling passes is 3 times, and the fiber entanglement degree is 85%, which improves the anti-delamination ability.

[0048] (5) Drying treatment: The composite layer after high-pressure hydroentangling is dried and shaped in a drying oven; the process conditions for the drying and shaping are: first drying at 100 °C for 2 min, then drying at 85 °C for 3 min, and finally drying at 70 °C for 2 min.

[0049] (6) Surface treatment: After drying, the sea-island layer is subjected to surface grinding and raising treatment to obtain the environmentally friendly regenerated leather, and various colors and textures can also be made according to the genuine leather process.

[0050] For the environmentally friendly regenerated leather obtained by the above method, the formaldehyde emission is detected according to GB / T 19941-2005, which is green and environmentally friendly, and the leather is soft.

[0051] After testing (the tensile strength is based on GB / T 3923.1-2013, the air permeability is based on ISO 9237:1995, and the peel strength is based on QB / T 2710-2005), its tensile strength is 17 MPa, the air permeability is 870 mL / (cm 2 ·h), and the interlayer peel strength is 5.5 MPa.

[0052] Example 2

[0053] The present invention discloses a preparation method of environmentally friendly regenerated leather, using waste leather scraps of cowhide as raw materials, and the specific steps are as follows:

[0054] (1) Fibrosis treatment: Collect waste leather scraps of cowhide, after cleaning, cut them into small pieces of 5-10 mm, and soak the small pieces of cowhide in papain at a pH value of 7 and a temperature of 40 °C for 2 hours to soften them and reduce the difficulty of fiber separation.

[0055] Then, the softened cowhide is pretreated by high-pressure hydroentangling at 20 MPa and added with 0.4 wt% sophorolipid to reduce the surface tension of the cowhide fibers and obtain cowhide fibers.

[0056] The obtained cowhide fibers are first impregnated in a 3 wt% chitosan acetate solution with a pH value of 4.5 for 1 h to enhance the subsequent binding force between the cowhide fibers and the sea-island fibers.

[0057] After squeezing out 95% of the impregnating liquid from the cowhide fibers, a 2% mass concentration of nanocellulose suspension (with a particle size of 50 nm) is evenly sprayed to increase the interfacial friction coefficient of the cowhide fibers.

[0058] (2) Wet-laying: Immerse the obtained bovine fibers in warm water at 45°C with a solid-liquid ratio of 1:35 and adding 0.5% TX-100 for 30 minutes to reduce the fiber surface energy.

[0059] Then, mix them in a dispersion with a pH value of 7 and adding 0.1% polyethylene oxide at a proportion of 0.5 wt% bovine fiber content, and disperse and stir with a high-speed shear machine at a rotation speed of 2500 r / min for 20 min to prepare a suspension.

[0060] The obtained suspension flows through an inclined screen former with a screen curtain mesh number of 80 at a speed of 1.0 m / min, and is vacuum dehydrated to a moisture content of 70% to obtain a fiber cloth with a grammage of 100 g / m 2 of the fiber cloth.

[0061] (3) Composite with sea-island fibers: Uniformly spread sea-island fibers on the upper surface of the fiber cloth prepared above, and transport it into a negative pressure adsorption device with -0.05 MPa to preliminarily bond the sea-island fibers to the fiber cloth to form a sea-island layer. The spreading amount of the sea-island fibers is controlled so that the thickness ratio of the fiber cloth to the sea-island layer is 1:3. Then, perform pre-entanglement with 10 MPa low-pressure hydroentanglement to form a composite layer, and form an "inverted hook type" mechanical anchoring structure between the fibers to enhance the interlayer bonding strength.

[0062] (4) High-pressure hydroentanglement: Use gradient high-pressure hydroentanglement to perform forward piercing, reverse piercing, and bidirectional alternating diagonal piercing on the composite layer in step (3) in sequence to achieve three-dimensional entanglement.

[0063] Specifically, the water pressures of the forward piercing, reverse piercing, and bidirectional alternating diagonal piercing increase in a gradient;

[0064] For the forward piercing, the water pressure is 30 MPa, from the side of the fiber cloth 10 to the side of the sea-island layer 20;

[0065] For the reverse piercing, the water pressure is 40 MPa, from the side of the sea-island layer 20 to the side of the fiber cloth 10;

[0066] For the bidirectional alternating diagonal piercing, the water pressure is 50 MPa, the diagonal piercing angle is 60°, and it penetrates bidirectionally.

[0067] The number of hydroentanglement passes is 3 times, and the fiber entanglement degree is 85% to improve the delamination resistance ability.

[0068] (5) Drying treatment: Dry and shape the composite layer after high-pressure hydroentanglement in a drying oven; the process conditions for the drying and shaping are: first dry at 100°C for 2 min, then dry at 85°C for 3 min, and finally dry at 70°C for 2 min.

[0069] (6) Surface treatment: After drying, the sea-island layer is subjected to surface grinding and raising treatment to obtain the environmentally friendly regenerated leather, and various colors and textures can also be made according to the genuine leather process.

[0070] For the environmentally friendly regenerated leather obtained by the above method, no formaldehyde emission is detected according to GB / T 19941-2005, it is green and environmentally friendly, and the leather is soft.

[0071] After testing (tensile strength is based on GB / T 3923.1-2013, air permeability is based on ISO 9237:1995, peel strength is based on QB / T 2710-2005), its tensile strength is 19 MPa, and the air permeability is 865 mL / (cm 2 ·h), and the interlayer peel strength is 5.8 MPa.

[0072] Comparative Example 1

[0073] The difference from Example 1 is that in step (4), the water pressure used for high-pressure hydroentanglement is 20 MPa.

[0074] The obtained fiber entanglement degree is 65%, and the interlayer peel strength of the obtained environmentally friendly regenerated leather is 3.8 MPa.

[0075] Comparative Example 2

[0076] The difference from Example 1 is that in step (4), the water pressure used for high-pressure hydroentanglement is 70 MPa, the obtained fiber entanglement degree is 98%, the bovine fiber and the sea-island fiber are completely mixed under the action of high-pressure water, and the obtained environmentally friendly regenerated leather loses the genuine leather texture.

[0077] Comparative Example 3

[0078] The difference from Example 1 is that in step (4), the high-pressure hydroentanglement only performs forward piercing treatment on the composite layer in step (3).

[0079] The obtained fiber entanglement degree is 70%, and the interlayer peel strength of the obtained environmentally friendly regenerated leather is 3.6 MPa.

[0080] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A preparation method of environmentally friendly regenerated leather, characterized in that, It includes the following steps: (1) Fibrosis treatment: Collect animal skin scraps and perform fibrosis treatment to obtain corresponding fibers; (2) Wet laying: Wet lay the obtained fibers to obtain a fiber cloth; (3) Composite with sea-island fibers: Uniformly spread sea-island fibers on one surface of the fiber cloth to form a sea-island layer. After preliminary lamination in a negative pressure adsorption device, perform pre-entanglement with low-pressure hydroentangling at 5-10 MPa to form a composite layer; (4) High-pressure hydroentangling: Use gradient high-pressure hydroentangling to perform forward piercing, reverse piercing, and bidirectional alternating diagonal piercing on the composite layer in step (3) in sequence to achieve three-dimensional entanglement of the composite layer, where: The forward piercing water pressure is 25-30 MPa, from the fiber cloth side to the sea-island layer side; The reverse piercing water pressure is 30-40 MPa, from the sea-island layer side to the fiber cloth side; The bidirectional alternating diagonal piercing water pressure is 40-50 MPa. (5) Drying treatment: Dry and shape the composite layer after high-pressure hydroentangling in a drying oven; (6) Surface treatment: After drying, perform surface grinding and raising on the sea-island layer to obtain the environmentally friendly regenerated leather.

2. The preparation method of the environmentally friendly recycled leather according to claim 1, characterized in that, In step (1), the method of the fibrosis treatment is: First, soften the collected animal skin scraps with neutral protease, and then perform pretreatment on the softened leather with high-pressure hydroentangling at 20-30 MPa to obtain corresponding fibers and perform fiber modification treatment.

3. The preparation method of the environmentally friendly regenerated leather according to claim 2, characterized in that, The method of the fiber modification treatment is: First, immerse in a chitosan acetate solution with a mass concentration of 2-5% and a pH value of 4-5 for 1-2 h. After taking out and squeezing out the immersion liquid, then spray a nanocellulose suspension with a mass concentration of 1-3%.

4. The preparation method of the environmentally friendly regenerated leather according to claim 2, characterized in that, 0.3-0.8% of a biological surfactant is added to the hydroentangling liquid of the high-pressure hydroentangling.

5. The preparation method of the environmentally friendly regenerated leather according to claim 1, characterized in that, In step (2), the grammage of the fiber cloth is 80 to 150 g / m 2 .

6. The preparation method of the environmentally friendly regenerated leather according to claim 1, characterized in that, In step (3), the vacuum degree of the negative pressure is -0.05 to -0.08 MPa; the pressure of the low-pressure hydroentangling is 5-10 MPa.

7. The preparation method of the environmentally friendly regenerated leather according to claim 1, characterized in that, In step (3), in the composite layer, the thickness ratio of the fiber cloth to the sea-island layer is 1:2 to 1:

3.

8. The preparation method of the environmentally friendly recycled leather according to claim 1, characterized in that, In step (4), the angle of the bidirectional alternating diagonal piercing is 40-60°; the fiber entanglement degree after the three-dimensional entanglement is ≥85%.

9. The preparation method of the environmentally friendly regenerated leather according to claim 1, characterized in that, In step (5), the process conditions for drying and shaping are: First, dry at 100-105 °C for 1-3 min, then dry at 80-90 °C for 2-5 min, and finally dry at 65-70 °C for 1-3 min.

10. An environmentally friendly recycled leather, characterized in that, Prepared by the method according to any one of claims 1-9, the environmentally friendly regenerated leather includes a bovine fiber layer and a sea-island fiber layer, where the mass ratio of bovine fiber to sea-island fiber is 1:1 to 1:2.

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