Production method of natural leather with water resistance and ultraviolet radiation resistance

Abstract

The invention belongs to the technical field of leather processing, and discloses a production method of natural leather with water resistance and ultraviolet radiation resistance. According to the method, wet blue leather or wet white leather subjected to shaving is rewetted through acid protease, neutralized crust leather is treated through a waterproof retanning fatting agent containing microcapsules and a waterproof fatting agent containing microcapsules in sequence, and then end capping treatment is conducted through a metal tanning agent; and finally, sequentially carrying out surface treatment on the natural leather by adopting a finishing agent containing an inorganic oxide and a water-sprinkling agent. According to the present invention, the basic performance of the natural leather can be ensured while the water resistance and the ultraviolet radiation resistance are provided, the dynamic water resistance frequency can achieve 250000 or more, the ultraviolet protection factor (UPF) can achieve 45 or more, the function of the natural leather is further increased and improved, and the requirements of people on the natural leather with the water resistance and the ultraviolet radiation resistance are met.

Description

Technical Field

[0001] The invention belongs to the technical field of leather processing and relates to a production method of natural leather with waterproof and ultraviolet radiation protection properties. Background Art

[0002] Throughout the history of the leather industry, traditional production technologies have primarily focused on achieving the basic functions of leather. However, with socioeconomic development and improvements in people's living standards, the market is demanding higher quality and more functional properties for natural leather products, with water resistance and UV protection receiving widespread attention. To impart these properties to natural leather, researchers and industry practitioners have conducted extensive research.

[0003] In terms of waterproofing, natural leather, a complex of collagen fibers, tanning agents, and other chemical products, is highly hydrophilic. Therefore, natural leather products that haven't been waterproofed may exhibit poor adaptability. Traditional leather waterproofing processes often rely on oil filling or surface coating, but these methods are limited in effectiveness and lack durability. Leather can easily deform or mold in humid environments, seriously affecting the appearance and lifespan of leather products. Studies have shown that wearing ordinary leather shoes in rainy conditions can cause water seepage, deformation, and even cracking in the uppers.

[0004] In terms of UV radiation protection, traditional production processes are not specifically designed to enhance leather's UV radiation resistance. Leather exposed to high-intensity UV radiation for long periods of time is susceptible to fading and aging, which not only affects its aesthetics but also weakens its physical and mechanical properties, significantly shortening the lifespan of leather products and limiting their applications. UV absorbers can effectively shield leather from the effects of UV radiation, thereby enhancing its UV radiation resistance and extending its lifespan. Organic absorbers offer excellent stability and high UV absorption rates, but they are prone to bioaccumulation, leading to accumulation and amplification effects. Inorganic absorbers (i.e., nano-oxides) offer excellent durability and enhance leather's UV radiation resistance, weatherability, antibacterial properties, and wear resistance. However, due to their tendency to aggregate, they are primarily used in leather finishing. Jia Fan et al. synthesized silver-titanium dioxide nanoparticles from quebracho tannin extract. While treated leather exhibits excellent UV light shielding capabilities, the cost of silver and the industrialization of related technologies have made industrial implementation of this technology difficult.

[0005] While research into the water- and UV-resistant properties of leather has made some progress, a mature, comprehensive, and industrially viable method has yet to be developed that ensures that finished leather retains its excellent properties of softness, breathability, and water vapor permeability while also possessing superior water- and UV-resistant properties. Against this backdrop, developing a method for producing natural leather with both water- and UV-resistant properties is crucial for improving its quality and expanding its application areas. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to address the deficiencies in the prior art and propose a method for producing natural leather with waterproof and ultraviolet radiation protection properties. The method comprises the following steps: firstly treating shaved wet blue leather or wet white leather with waterproof and ultraviolet radiation protection properties using a waterproof retanning fatliquor containing microcapsules, then treating it with a waterproof fatliquor containing microcapsules of inorganic oxides for a second time, and then treating it with inorganic oxides and a water repellent for a third time, thereby obtaining natural leather with waterproof and ultraviolet radiation protection properties, which can effectively reduce the potential harm of ultraviolet radiation to the human body and provide protection for travel on rainy days.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for producing natural leather with waterproof and UV radiation protection properties comprises the following steps:

[0009] (1) Rinse

[0010] Take 100 parts of shaved wet blue leather or wet white leather, add 100-150 parts of water at a temperature of 40-50°C, 0.2-0.5 parts of formic acid, and 0.2-0.5 parts of acid protease, rotate for 60-120 minutes, adjust the pH to 3.6-3.8, and wash with water;

[0011] The acidic protease used is derived from microbial fermentation and is a pepsin-like acidic protease with an optimum pH of 2.5-3.5 and an optimum temperature of 40-55°C.

[0012] (2) Adjusting the pH value of the leather

[0013] Use 100-150 parts of water at a temperature of 18-22°C, add 3-5 parts of neutralizer and 1.5-2.0 parts of baking soda into the drum, rotate for 60-120 minutes, adjust the pH value of the crust leather to 5.5-6.0, and wash with water;

[0014] The "neutralizing agent" used is a "neutralizing and retanning agent", which is a "synthetic tannin neutralizing and retanning agent" and its main component is a naphthalenesulfonic acid derivative.

[0015] (3) The first treatment for waterproofing and UV protection

[0016] 100-150 parts of water at a temperature of 35-45° C. are added into a drum (leather drum) with 3-5 parts of a pre-processed waterproof retanning fatliquor containing microcapsules, and the drum is rotated for 60-120 minutes. The pH value of the crust leather is adjusted to 5.2-5.6, and then washed with water;

[0017] (4) Second treatment for waterproofing and UV protection

[0018] 100-150 parts of water at a temperature of 35-45° C. are added into the drum with 15-20 parts of a pre-processed waterproof fatliquor containing microcapsules, and the drum is rotated for 90-120 minutes, the pH value of the crust leather is adjusted to 3.5-3.8, and then washed with water;

[0019] (5) End-capping treatment

[0020] Use 100-150 parts of water at a temperature of 35-45°C, add 1.0-2.0 parts of metal tanning agent into the drum, rotate for 30-60 minutes, and wash with water;

[0021] (6) Squeezing, stretching, drying, softening, and board stretching are all carried out according to conventional methods;

[0022] (7) The third treatment for waterproofing and UV protection

[0023] The surface of the leather behind the stretch board is coated or sprayed with a finishing agent containing 100 parts of pigment paste, 120-150 parts of medium-soft film-forming acrylic resin, 80-120 parts of polyurethane resin, 2-5 parts of inorganic oxide, and 300-400 parts of water, with the amount of 5-8g / SF respectively, and then dried and ironed;

[0024] (8) Top layer waterproofing

[0025] Spray a finishing agent containing 100-150 parts of a film-forming hard polyurethane resin, 100-150 parts of water, and 3-5 parts of a water-repellent on the surface of the leather in an amount of 3-5 g / SF, dry, and iron.

[0026] Preferably, the preparation method of the microcapsules is to add 1 to 10 parts of ultrasonically dispersed inorganic matter and 1 to 5 parts of emulsifier to a solution of chitosan (5 to 15 parts) and gelatin (1 to 10 parts), mix them thoroughly and evenly, and then heat them to form microcapsules with a diameter of 20 to 40 microns; wherein the inorganic matter is one or both of titanium dioxide and carbon nanotubes, and the emulsifier is one or both of a waterproof retanning fatliquor and a waterproof fatliquor.

[0027] Furthermore, the mass percentage of the microcapsules in the waterproof retanning fatliquor is 5-8%, and the mass percentage of the microcapsules in the waterproof fatliquor is 10-12%.

[0028] Furthermore, the waterproof retanning fatliquor is a polymer-type waterproof retanning fatliquor containing silicon and a hydrophobic long-chain structure. The main components are polymers of acrylic acid, methacrylic acid and its long-chain lipid monomers and high-ethylene silicone oil. For details, see patent CN202110114609.1, a silicon-containing polymer auxiliary agent and its preparation method, which have been produced by Shandong Li Ning Technology Co., Ltd.

[0029] Furthermore, the waterproof fatliquor is an organic silicon waterproof fatliquor or a reactive waterproof fatliquor, such as that produced by TRUMPLER of Germany.

[0030] Preferably, the metal tanning agent is one of aluminum tanning agent and chrome tanning agent, and the "aluminum tanning agent and chrome tanning agent" used are industrial products. Brother Technology Co., Ltd., Haining Heping Chemical Co., Ltd. and others all have such products.

[0031] Preferably, the water repellent is a liquid containing wax or fluorosilane.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention introduces hydrophobic long-chain molecules to combine with leather collagen fibers, giving leather good waterproof properties;

[0034] (2) The present invention does not use organic ultraviolet absorbers, which greatly reduces the harm to the environment and human body;

[0035] (3) In the present invention, the microcapsule technology integrates inorganic oxides with waterproof retanning fatliquor and waterproof fatliquor, and the prepared microcapsules are safe, environmentally friendly, efficient and long-lasting, and improve the anti-ultraviolet radiation performance without affecting the original air permeability of the leather;

[0036] (4) Acrylic resin and polyurethane resin coated on the leather surface wrap the inorganic oxide and wax or fluorosilane to form a network structure, thereby making the leather have better waterproof and UV radiation protection properties;

[0037] (5) The method disclosed in the present invention has a wide range of applications and is suitable for the production of leather products such as leather shoes, leather clothes, and leather bags, and can effectively prolong the aging time of leather. DETAILED DESCRIPTION

[0038] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] The term "embodiment" is used herein specifically to describe any embodiment as "exemplary," and should not be construed as superior or preferable to other embodiments. Performance indicators in the embodiments of this application were tested using conventional testing methods in the art, unless otherwise specified. It should be understood that the terms used in this application are intended solely to describe specific implementations and are not intended to limit the disclosure herein.

[0040] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0041] In order to better illustrate the content of this application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that this application can be implemented without certain specific details. In the examples, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of this application.

[0042] Under the premise of no conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of this application.

[0043] The invention discloses a production method of natural leather with waterproof and ultraviolet radiation protection properties.

[0044] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0045] Example 1

[0046] A method for producing natural leather with waterproof and UV radiation protection properties comprises the following steps:

[0047] (1) Rinse

[0048] 100 kg of shaved wet blue leather or wet white leather was taken and washed with 100 kg of 40°C water, 0.2 kg of formic acid, and 0.2 kg of acid enzyme 537 (Shandong Ruichen Biotechnology Co., Ltd.), rotated for 60 minutes, adjusted to pH 3.6, and washed with water;

[0049] (2) Adjusting the pH value of the leather

[0050] 100 kg of water at a temperature of 18°C ​​was used, 3 kg of neutralizing retanning agent NG (Derui Technology Co., Ltd.) and 1.5 kg of baking soda were added to the drum, the drum was rotated for 60 minutes, the pH value of the crust leather was adjusted to 5.5, and then washed with water;

[0051] (3) The first treatment for waterproofing and UV protection

[0052] 100 kg of water at 35°C was added to the drum, 3 kg of a pre-processed waterproof retanning fatliquor containing microcapsules was added, the drum was rotated for 60 minutes, the pH value of the crust leather was adjusted to 5.2, and the leather was washed with water;

[0053] The microcapsule preparation method is to add 1 kg of ultrasonically dispersed inorganic substances (one or two of titanium dioxide and carbon nanotubes) and 1 kg of waterproof retanning fatliquor LSW (Shandong Li Ning Technology Co., Ltd.) to a chitosan (5 kg)-gelatin (1 kg) solution, mix them thoroughly and then heat them to form microcapsules with a diameter of 20 microns.

[0054] (4) Second treatment for waterproofing and UV protection

[0055] 100 kg of water at 35° C. was added to a drum containing 15 kg of pre-processed microcapsule-containing waterproof fatliquor TRUSON D (TRUMPLER Co. Ltd.), and the drum was rotated for 90 minutes to adjust the pH value of the crust leather to 3.5, and then washed with water;

[0056] Among them, the preparation method of microcapsules is to add 1 kg of ultrasonically dispersed inorganic substances (one or two of titanium dioxide and carbon nanotubes) and 1 kg of emulsifier (waterproof fatliquor) to a solution of chitosan (5 kg) and gelatin (1 kg), mix them thoroughly and then heat them to form microcapsules with a diameter of 20 microns.

[0057] (5) End-capping treatment

[0058] 1.0 kg of metal tanning agent HLS-C (Brother Technology Co., Ltd.) was added to the drum using 100 kg of water at a temperature of 35°C, rotated for 30 minutes, and washed with water;

[0059] (6) Squeezing, stretching, drying, softening, and board stretching are all carried out according to conventional methods;

[0060] (7) The third treatment for waterproofing and UV protection

[0061] The leather surface behind the stretch board was coated with a finishing agent containing 100 kg of pigment paste, 120 kg of medium-soft film-forming acrylic resin, 80 kg of polyurethane resin, 2 kg of TiO2 (commercial product), and 300 kg of water, with the amount of 5 g / SF respectively, and then dried and ironed.

[0062] (8) Top layer waterproofing

[0063] The leather surface is sprayed with a finishing agent containing 100 kg of film-forming hard polyurethane resin, 100 kg of water, and 3 kg of water-repellent at a dosage of 3 g / SF, dried, and ironed.

[0064] Example 2

[0065] A method for producing natural leather with waterproof and UV radiation protection properties comprises the following steps:

[0066] (1) Rinse

[0067] 100 kg of shaved wet blue leather or wet white leather was taken and washed with 150 kg of 50°C water, 0.5 kg of formic acid, and 0.5 kg of acid enzyme 537 (Shandong Ruichen Biotechnology Co., Ltd.), rotated for 120 minutes, adjusted to pH 3.8, and washed with water;

[0068] (2) Adjusting the pH value of the leather

[0069] 150 kg of water at a temperature of 22° C. was used, and 5 kg of neutralizing retanning agent NG (Derui Technology Co., Ltd.) and 2.0 kg of baking soda were added to the drum, and the drum was rotated for 120 minutes. The pH value of the crust leather was adjusted to 6.0, and then washed with water;

[0070] (3) The first treatment for waterproofing and UV protection

[0071] 150 kg of water at a temperature of 45° C. were added to the drum, 5 kg of a pre-processed waterproof retanning fatliquor containing microcapsules was added, the drum was rotated for 120 minutes, the pH value of the crust leather was adjusted to 5.6, and the leather was washed with water;

[0072] The microcapsule preparation method is to add 10 kg of ultrasonically dispersed inorganic substances (one or two of titanium dioxide and carbon nanotubes) and 5 kg of waterproof retanning fatliquor LSW (Shandong Li Ning Technology Co., Ltd.) to a chitosan (15 kg)-gelatin (10 kg) solution, mix them thoroughly and then heat them to form microcapsules with a diameter of 40 microns.

[0073] (4) Second treatment for waterproofing and UV protection

[0074] 150 kg of water at 45° C. were added to a drum containing 20 kg of pre-processed microcapsule-containing waterproof fatliquor TRUSON D (TRUMPLER Co. Ltd.), and the drum was rotated for 120 minutes to adjust the pH value of the crust leather to 3.8, and then washed with water;

[0075] Among them, the preparation method of microcapsules is to add 10 kg of ultrasonically dispersed inorganic substances (one or two of titanium dioxide and carbon nanotubes) and 5 kg of emulsifier (waterproof fatliquor) to a solution of chitosan (15 kg) and gelatin (10 kg), mix them thoroughly and then heat them to form microcapsules with a diameter of 40 microns.

[0076] (5) End-capping treatment

[0077] 150 kg of water at a temperature of 45°C was used, and 2.0 kg of metal tanning agent HLS-C (Brother Technology Co., Ltd.) was added to the drum, rotated for 60 minutes, and washed with water;

[0078] (6) Squeezing, stretching, drying, softening, and board stretching are all carried out according to conventional methods;

[0079] (7) The third treatment for waterproofing and UV protection

[0080] The leather surface behind the stretch board was coated with a finishing agent containing 100 kg of pigment paste, 150 kg of medium-soft film-forming acrylic resin, 120 kg of polyurethane resin, 5 kg of TiO2 (commercial product), and 400 kg of water, with the amount of 8 g / SF respectively, and then dried and ironed.

[0081] (8) Top layer waterproofing

[0082] The leather surface is sprayed with a coating agent containing 150 kg of film-forming hard polyurethane resin, 150 kg of water, and 5 kg of water-repellent at a dosage of 5 g / SF, dried, and ironed.

[0083] Example 3

[0084] A method for producing natural leather with waterproof and UV radiation protection properties comprises the following steps:

[0085] (1) Rinse

[0086] 100 kg of shaved wet blue leather or wet white leather was taken and washed with 125 kg of 45°C water, 0.35 kg of formic acid, and 0.35 kg of acid enzyme 537 (Shandong Ruichen Biotechnology Co., Ltd.), rotated for 90 minutes, adjusted to pH 3.7, and washed with water;

[0087] (2) Adjusting the pH value of the leather

[0088] 125 kg of water at 20°C was used, 4 kg of neutralizing retanning agent NG (Derui Technology Co., Ltd.) and 1.75 kg of baking soda were added to the drum, the drum was rotated for 90 minutes, the pH value of the crust leather was adjusted to 5.7, and then washed with water;

[0089] (3) The first treatment for waterproofing and UV protection

[0090] 125 kg of water at 40°C was added to the drum, 4 kg of a pre-processed waterproof retanning fatliquor containing microcapsules was added, the drum was rotated for 90 minutes, the pH value of the crust leather was adjusted to 5.4, and the leather was washed with water;

[0091] Among them, the preparation method of microcapsules is to add 5.5 kg of ultrasonically dispersed inorganic substances (one or two of titanium dioxide and carbon nanotubes) and 3 kg of waterproof retanning and fatliquor LSW (Shandong Lining Technology Co., Ltd.) to a solution of chitosan (10 kg) and gelatin (5.5 kg), mix them thoroughly and then heat them to form microcapsules with a diameter of 30 microns.

[0092] (4) Second treatment for waterproofing and UV protection

[0093] 17.5 kg of pre-processed microcapsule-containing waterproof fatliquor TRUSON D (TRUMPLER Co. Ltd) was added to the drum using 125 kg of water at 40°C, and the drum was rotated for 105 minutes to adjust the pH value of the crust leather to 3.6, and then washed with water;

[0094] Among them, the preparation method of microcapsules is to add 5.5 kg of ultrasonically dispersed inorganic substances (one or two of titanium dioxide and carbon nanotubes) and 3 kg of emulsifier (waterproof fatliquor) to a solution of chitosan (10 kg) and gelatin (5.5 kg), mix them thoroughly and then heat them to form microcapsules with a diameter of 30 microns.

[0095] (5) End-capping treatment

[0096] Use 125 kg of water at a temperature of 40°C, add 1.5 kg of metal tanning agent HLS-C (Brother Technology Co., Ltd.) into the drum, rotate for 45 minutes, and wash with water;

[0097] (6) Squeezing, stretching, drying, softening, and board stretching are all carried out according to conventional methods;

[0098] (7) The third treatment for waterproofing and UV protection

[0099] The leather surface behind the stretch board was coated with a finishing agent containing 100 kg of pigment paste, 135 kg of medium-soft film-forming acrylic resin, 100 kg of polyurethane resin, 3.5 kg of TiO2 (commercial product), and 350 kg of water, with the amount of 6.5 g / SF respectively, and then dried and ironed.

[0100] (8) Top layer waterproofing

[0101] The leather surface was sprayed with a coating agent containing 125 kg of a film-forming hard polyurethane resin, 125 kg of water, and 4 kg of a water-repellent at a dosage of 4 g / SF, and then dried and ironed.

[0102] Comparative Example

[0103] A method for producing natural leather comprises the following steps:

[0104] (1) Retanning

[0105] 100 kg of shaved wet blue leather was tanned with 100 kg of 35°C water and 1 kg of fatty aldehyde tanning agent CRS (Sichuan Dawei Chemical Company) and rotated for 30 minutes; 2 kg of zirconium-aluminum-titanium multimetallic complex tanning agent (Mianyang Jinkun Chemical Company) and 1 kg of waterproof oil POL (TFL Company) were added and rotated for 90 minutes; 1 kg of sodium formate was added and rotated for 30 minutes; 0.6 kg of baking soda was added, the pH was adjusted to 4.2, and the leather was rotated for 60 minutes; 100 kg of water was added, the temperature was raised to 40°C, the leather was rotated for 30 minutes, and the leather was stopped for overnight; the leather was rotated for 30 minutes the next day, and the leather was washed with 300 parts of normal temperature water for 10 minutes and drained;

[0106] (2) Filling

[0107] 50 kg of water at a temperature of 28-35°C was used to disperse 2 kg of tannin Tamol M (BASF, Germany) and rotated for 30 minutes. During the rotation, 0.5 kg of protein filler FB (Sichuan Desaier Chemical Co., Ltd.), 3.5 kg of acrylic acid retanning agent SOF (TFL Co., Ltd.), 4 kg of melamine retanning agent RX-L (Sichuan Mingzhong Chemical Co., Ltd.), and 1 kg of silicone polymer TJ-A9991 (Tingjiang New Materials Co., Ltd.) were added. The pH was adjusted to 5.5 and the mixture was rotated for 180 minutes. 0.5 kg of formic acid was added in three portions, each time rotating for 20 minutes and then resting for 30 minutes, until the pH reached 3.8-4.2.

[0108] (3) Fat addition

[0109] Add 150 kg of hot water at 58-62°C (control the temperature inside the drum at 50°C) and rotate for 10 minutes; add 9.0 kg of waterproof fatliquor WRM-N (TFL), 4.5 kg of HQ (Schill+Seilacher, Germany), 4.5 kg of WAM (TFL), 4.5 kg of lanolin ZBN (BIOKIMICA, Italy), and 4.5 kg of waterproof oil CD (BASF), and rotate for 60 minutes; add 150 kg of hot water at 50°C, add 1 kg of cationic fatliquor GS (STAHL), and rotate for 60 minutes; add 0.3 kg of formic acid in two times, rotate for 20 minutes, the pH is 3.4-3.6, and wash with 300 kg of hot water at 55°C for 10 minutes.

[0110] (4) Painting

[0111] The finishing process includes primer, topcoat, and topcoat, as well as mechanical treatments such as calendering, polishing, and tumbling. Except for the topcoat, all other processes were carried out according to conventional techniques. The topcoat's finishing agent contains functionalized graphene oxide-modified silicone. The coating weights for the primer, topcoat, and topcoat were 10g / SF, 15g / SF, and 8g / SF, respectively.

[0112] According to the leather waterproof standard GB / T 22890-2008 and ASTM D7334-18, the dynamic and static waterproof properties of leather were tested using a Bally leather dynamic waterproof testing machine and an optical contact angle meter. According to the textile UV protection standard GB / T18830-2009, the UV protection factor (UPF) of leather was tested using a UV-2000F UV transmission performance tester.

[0113] The test results of the leather prepared in Example and Comparative Example are as follows:

[0114] Test items Example 1 Example 2 Example 3 Comparative Example Contact angle / ° 130 130 130 120 Dynamic waterproof times 250,000+ 250,000+ 250,000+ 200,000 Ultraviolet Protection Factor (UPF) 45 45 45 15

[0115] As can be seen from the table, the contact angle of the product produced using the method of the present invention can reach 130° or above, which is greater than the contact angle of the comparative example, indicating that it has good static waterproof performance. At the same time, its dynamic waterproof number is 250,000+, exceeding the dynamic waterproof number of the comparative example, indicating that it has good dynamic waterproof performance. Therefore, the product produced by the method of the present invention has excellent waterproof performance. In addition, the product produced by the method of the present invention is significantly better than the comparative example in terms of ultraviolet protection factor (UPF) test results, indicating that it has excellent ultraviolet resistance.

[0116] In summary, the method of the present invention has obvious advancements, and the products produced have excellent waterproof and ultraviolet radiation protection properties.

[0117] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing natural leather with waterproof and UV radiation protection properties, characterized in that: The method specifically comprises the following steps: (1) Rinse Take 100 parts of shaved wet blue leather or wet white leather, add 100-150 parts of water at a temperature of 40-50°C, 0.2-0.5 parts of formic acid, and 0.2-0.5 parts of acid protease, rotate for 60-120 minutes, adjust the pH to 3.6-3.8, and wash with water; (2) Adjusting the pH value of the leather Use 100-150 parts of water at a temperature of 18-22°C, add 3-5 parts of neutralizer and 1.5-2.0 parts of baking soda into the drum, rotate for 60-120 minutes, adjust the pH value of the crust leather to 5.5-6.0, and wash with water; (3) The first treatment for waterproofing and UV protection 100-150 parts of water at a temperature of 35-45° C. are added into the drum with 3-5 parts of a pre-processed waterproof retanning fatliquor containing microcapsules, and the drum is rotated for 60-120 minutes, the pH value of the crust leather is adjusted to 5.2-5.6, and then washed with water; (4) Second treatment for waterproofing and UV protection 100-150 parts of water at a temperature of 35-45° C. are added into the drum with 15-20 parts of a pre-processed waterproof fatliquor containing microcapsules, and the drum is rotated for 90-120 minutes, the pH value of the crust leather is adjusted to 3.5-3.8, and then washed with water; (5) End-capping treatment Use 100-150 parts of water at a temperature of 35-45°C, add 1.0-2.0 parts of metal tanning agent into the drum, rotate for 30-60 minutes, and wash with water; (6) Squeezing, stretching, drying, softening, and board stretching are all carried out according to conventional methods; (7) The third treatment for waterproofing and UV protection The surface of the leather behind the stretch board is coated or sprayed with a finishing agent containing 100 parts of pigment paste, 120-150 parts of medium-soft film-forming acrylic resin, 80-120 parts of polyurethane resin, 2-5 parts of inorganic oxide, and 300-400 parts of water, with the amount of 5-8g / SF respectively, and then dried and ironed; (8) Top layer waterproofing Spray a finishing agent containing 100-150 parts of a film-forming hard polyurethane resin, 100-150 parts of water, and 3-5 parts of a water-repellent on the surface of the leather in an amount of 3-5 g / SF, dry, and iron.

2. The method for producing natural leather with waterproof and UV radiation protection properties according to claim 1, characterized in that: The preparation method of microcapsules is as follows: Add 1-10 parts of the ultrasonically dispersed inorganic substance and 1-5 parts of the emulsifier to a solution of chitosan (5-15 parts) and gelatin (1-10 parts), mix thoroughly and heat to form microcapsules with a diameter of 20-40 microns; The inorganic substance is one or both of titanium dioxide and carbon nanotubes, and the emulsifier is one or both of waterproof retanning fatliquor and waterproof fatliquor.

3. The method for producing natural leather with waterproof and UV radiation protection properties according to claim 2, characterized in that: The mass percentage of the microcapsules in the waterproof retanning fatliquor is 5-8%, and the mass percentage of the microcapsules in the waterproof fatliquor is 10-12%.

4. The method for producing natural leather with waterproof and UV radiation protection properties according to claim 3, characterized in that: The waterproof retanning fatliquor is a polymer-type waterproof retanning fatliquor containing silicon and a hydrophobic long-chain structure, and its main components are a polymer of acrylic acid, methacrylic acid and its long-chain lipid monomers and high-ethylene silicone oil.

5. The method for producing natural leather with waterproof and UV radiation protection properties according to claim 3, characterized in that: The waterproof fatliquor is an organosilicon waterproof fatliquor or a reactive waterproof fatliquor.

6. The method for producing natural leather with waterproof and UV radiation protection properties according to claim 1, characterized in that: The metal tanning agent is one of aluminum tanning agent and chrome tanning agent.

7. The method for producing natural leather with waterproof and UV radiation protection properties according to claim 1, characterized in that: The water repellent is an organosilicon water repellent, the main component of which is a siloxane polymer.