Breathable and matte nano-composite finishing agent for water-based leather as well as preparation method and application of nano-composite finishing agent

Abstract

The invention discloses a breathable and matte nano-composite finishing agent for water-based leather as well as a preparation method and application of the breathable and matte nano-composite finishing agent, and relates to the technical field of leather finishing agents. From the perspective of the chain extender, the problem that a traditional finishing agent is poor in air permeability is solved, leather products are more comfortable and sanitary, and meanwhile the problem that the performance of the finishing agent is reduced due to the fact that a delustering agent and an emulsifying agent are added is solved; silica nanoparticles with mesoporous structures are used as chain extenders, so that not only can places be provided for guest molecules, but also channels can be provided for the guest molecules, and the guest molecules can be stored, released and the like, so that the aim of improving the air permeability of the coating agent is fulfilled; meanwhile, the silicon dioxide nanoparticles can also play a role in extinction, and compared with a traditional method of directly adding a matting agent, the scratch resistance can also be improved; in addition, rich hydroxyl groups on the surfaces of the silicon dioxide nanoparticles can also improve the stability of the resin in water, so that the effect of emulsifying in water is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of leather finishing agents, and particularly relates to a breathable and matte water-based nano-composite finishing agent for leather, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous consumption upgrade of the leather market, people increasingly pursue high-grade leather products, which not only need to meet the aesthetic needs of consumers in terms of texture, gloss, color, etc., but also need to provide better comfort and diversified functions. Whether the leather product is breathable is an important manifestation of its comfort and hygiene.

[0003] Leather finishing agents can form a uniform polymer film on the leather surface through cross-linking, which can effectively improve the appearance and style of the leather, and at the same time improve its basic physical properties. However, this dense film will also greatly reduce the breathability of leather products, seriously blocking the channels for water vapor to diffuse to the outside, and at the same time being unfavorable for the volatilization of harmful substances during the leather production process, reducing the product quality. At present, few leather finishing agents consider relevant properties such as breathability in their design.

[0004] At the same time, leather finishing agents also play an important role in reducing the gloss of the leather surface and preventing the resin layer from being too bright and generating a plastic feeling. One of the important matting methods at present is to add a matting agent to the finishing agent. However, this direct addition method is difficult to make the matting agent and the finishing agent into a unified whole, which will affect the scratch resistance and wear resistance of the film formed by the finishing agent.

[0005] In addition, traditional oil-based finishing agents contain a large amount of volatile solvents, which cause great environmental pollution and have safety hazards such as flammability and explosiveness. They are gradually being phased out by water-based finishing agents with the advantages of environmental protection, safety, and easy cleaning. The main component of water-based finishing agents is a high molecular weight polyurethane prepolymer. To achieve stable storage in water, an emulsifier is required. For example, if an external emulsifier is used to forcibly emulsify polyurethane in water by high shear force, the obtained polyurethane particles have a large particle size and poor stability, and at the same time their film-forming property is also poor. Therefore, the hydrophilicity of leather finishing agents based on polymers is also one of the important considerations in design. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of a breathable, matte water-based nano-composite finishing agent for leather. Using silica nanoparticles with a mesoporous structure as a chain extender, the polyurethane resin is given the properties of breathability, hydrophilicity, and scratch resistance, and finally a functionalized leather product is obtained, providing a new idea for the design of finishing agents.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A preparation method of a breathable and matte water-based nano-composite finishing agent for leather, the steps are as follows:

[0008] S1. Prepare silica nanoparticles with a mesoporous structure;

[0009] S2. Mix and react toluene diisocyanate and polytetramethylene ether glycol, and add the mesoporous silica prepared in step S1;

[0010] S3. Add deionized water and obtain the aqueous nano-composite finishing agent for leather by stirring and emulsifying.

[0011] Further, in the preparation method of the above-mentioned breathable and matte aqueous nano-composite finishing agent for leather, the molar ratio of the toluene diisocyanate to the polytetramethylene ether glycol is 1-3:1-3.

[0012] Further, in the preparation method of the above-mentioned breathable, matte aqueous nano-composite finishing agent for leather, the addition amount of the nanoparticles is 1-6% of the mass of the toluene diisocyanate and the polytetramethylene ether glycol.

[0013] Further, in the preparation method of the above-mentioned breathable and matte aqueous nano-composite finishing agent for leather, the solid content of the nano-composite finishing agent for leather is 15-30%.

[0014] Further, in the preparation method of the above-mentioned breathable and matte aqueous nano-composite finishing agent for leather, both the chain extender and the emulsifier are nanoparticles with a mesoporous structure. Further, in the preparation method of the above-mentioned breathable and matte aqueous nano-composite finishing agent for leather, the nanoparticles are mesoporous silica nanoparticles.

[0015] Further, in the preparation method of the above-mentioned breathable and matte aqueous nano-composite finishing agent for leather, preparing the nanoparticles with a mesoporous structure includes the following steps:

[0016] S11. Using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer as a template agent and tetraethyl orthosilicate as a silicon source, synthesize by the sol-gel method for 24 h, and the mass ratio of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer to the tetraethyl orthosilicate is 1-3:3-7;

[0017] S12. Transfer the synthesis product of step S11 to a stainless steel autoclave, keep it at 100-150 °C for 24-48 h, and then calcine it at a temperature of 550-700 °C to obtain silica nanoparticles with a mesoporous structure.

[0018] The present invention also provides an aqueous nano-composite finishing agent for leather prepared by using the above-mentioned preparation method of the breathable and matte aqueous nano-composite finishing agent for leather.

[0019] The present invention also provides an application of the above-mentioned breathable and matte water-based nano-composite finishing agent for leather in leather production. The leather includes a leather body and a sizing agent coated on the surface of the leather body. The sizing agent includes 5 parts of a curing agent and 100 parts of the nano-composite finishing agent for leather.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The present invention uses silica nanoparticles with a mesoporous structure as a chain extender. Since the silica surface has abundant hydroxyl groups, polyurethane resin can be prepared through a chain extension reaction with isocyanate. And the mesoporous structure of the silica nanoparticles can provide a site and a channel for guest molecules, and at the same time play functions such as storage and release of guest molecules, so as to achieve the purpose of improving the breathability of the finishing agent. At the same time, the abundant hydroxyl groups can also form hydrogen bonds with water molecules, enabling the polyurethane with silica as a chain extender to stably exist in water, avoiding the adverse effects brought by the need to add another emulsifier. In addition, introducing silica inorganic nanoparticles into the polyurethane in the form of a chain extender can not only make its surface rough microscopically when forming a film, increasing the scattering ability of incident light to achieve the purpose of matting, but also avoid problems such as the decline in scratch resistance caused by the direct addition of a matting agent, and finally obtain a functional leather that is breathable and matte. Description of the Drawings

[0022] Figure 1 It is a reaction schematic diagram of the breathable and matte water-based nano-composite finishing agent for leather of the present invention. Detailed Embodiments

[0023] Refer to Figure 1 As shown, a preparation method of a breathable and matte water-based nano-composite finishing agent for leather is as follows:

[0024] S1. Prepare silica nanoparticles with a mesoporous structure:

[0025] S11. Using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer as a template agent and tetraethyl orthosilicate as a silicon source, carry out a sol-gel synthesis reaction for 24 h. The mass ratio of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer to tetraethyl orthosilicate is 1-3:3-7;

[0026] S12. Transfer the synthesis product of step S11 to a stainless steel autoclave, keep it at 100-150 °C for 24-48 h, and then calcine it at a temperature of 550-700 °C to obtain silica nanoparticles with a mesoporous structure;

[0027] S2. Mix toluene diisocyanate and polytetramethylene ether glycol for reaction, and add the mesoporous silica nanoparticles prepared in step S12. The molar ratio of toluene diisocyanate to polytetramethylene ether glycol is 1-3:1-3, and the addition amount of the silica nanoparticles is 1-6% of the mass of toluene diisocyanate and polytetramethylene ether glycol;

[0028] S3. Add deionized water and obtain the aqueous nano-composite finishing agent for leather through stirring and emulsification, with a solid content of 15-30%.

[0029] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in this industry. Details are shown in Table 1. The methods in the following examples, unless otherwise specified, are all conventional methods in this field.

[0030] Table 1 Sources of experimental raw materials

[0031]

[0032] Example 1

[0033] The preparation of leather samples can be divided into the following steps:

[0034] S1. Prepare silica nanoparticles with a mesoporous structure:

[0035] S11. Using poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer as a template agent and tetraethyl orthosilicate as a silicon source, synthesize through the sol-gel method for 24 h. The mass ratio of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer to tetraethyl orthosilicate is 1-3:3-7;

[0036] S12. Transfer the synthesis product of step S11 to a stainless steel autoclave, keep it warm at 100-150 °C, and then calcine it at a temperature of 550-700 °C to obtain silica nanoparticles with a mesoporous structure;

[0037] S2. Mix toluene diisocyanate and polytetramethylene ether glycol for reaction, and add the mesoporous silica nanoparticles prepared in step S12. The molar ratio of toluene diisocyanate to polytetramethylene ether glycol is 1-3:1-3, and the addition amount of the silica nanoparticles is 4% of the mass of toluene diisocyanate and polytetramethylene ether glycol;

[0038] S3. Add deionized water and obtain the aqueous nano-composite finishing agent for leather through stirring and emulsification, with a solid content of 15-30%;

[0039] S4: Configure the surface treatment layer slurry and apply it to the leather body to prepare test leather samples: The slurry contains the following raw materials by weight: 100 parts of the waterborne finishing agent prepared above, 5 parts of the curing agent. Among them, the leather body is conventional genuine leather or synthetic leather, etc. The same kind of leather is used in both the examples and the comparative examples.

[0040] S5: Perform embossing treatment on the finished leather samples.

[0041] Example 2

[0042] The synthesis of the finishing agent in this solution is the same as that in step S2 of Comparative Example 1, except that the addition amount of silica nanoparticles is 5% of the mass of toluene diisocyanate and polytetramethylene ether glycol. The rest of the test conditions are the same as those in Example 1.

[0043] Example 3

[0044] The synthesis of the finishing agent in this solution is the same as that in step S2 of Comparative Example 1, except that the addition amount of silica nanoparticles is 6% of the mass of toluene diisocyanate and polytetramethylene ether glycol. The rest of the test conditions are the same as those in Example 1.

[0045] Comparative Example 1

[0046] The synthesis of the finishing agent in this solution is the same as that in step S2 of Comparative Example 1, except that the chain extender is not used. The rest of the test conditions are the same as those in Example 1.

[0047] Comparative Example 2

[0048] The synthesis of the finishing agent in this solution is the same as that in step S2 of Example 1, except that the chain extender is not used. When configuring the surface treatment layer slurry, the mesoporous silica prepared in step S1 of Example 1 is directly added, and the addition amount is 5% of the mass of toluene diisocyanate and polytetramethylene ether glycol. The rest of the test conditions are the same as those in Example 1.

[0049] Comparative Example 3

[0050] The synthesis of the finishing agent in this solution is the same as that in step S2 of Example 1, except that the chain extender is not used, and it is emulsified by the external emulsification method. The emulsifier used is sodium dodecyl sulfate. The rest of the test conditions are the same as those in Example 1.

[0051] Visually observe the stability of the waterborne finishing agents prepared in Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, Comparative Example 3, observe the emulsion state and storage stability of the finishing agent, and reflect its hydrophilicity. The results are shown in Table 1.

[0052] Table 1 Stability of waterborne finishing agents

[0053]

[0054] As can be seen from Table 1, the presence of hydrophilic substances can improve the stability of waterborne finishing agents. Compared with the external emulsification methods of Comparative Example 2 and Comparative Example 3, the waterborne finishing agents prepared by the internal emulsification method using hydrophilic mesoporous silica as a chain extender in Example 1, Example 2, and Example 3 have better stability and can be stored in water for a long time.

[0055] Glossiness tests were carried out on the leather samples (before embossing) prepared in Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, Comparative Example 3, and the extinction rate was calculated to reflect their matte characteristics. The matte effect was evaluated by the extinction rate. Using an ETB-0686 type glossiness tester with an incident angle of 60°, glossiness measurements were taken at multiple locations on the leather samples, and the average glossiness was taken. The formula for the extinction rate is as follows:

[0056] Extinction rate = (Z1 - Z2) / Z1 × 100%

[0057] In the formula, Z1 is the glossiness of the untreated substrate, and Z2 is the glossiness after treatment.

[0058] The test results are shown in Table 2.

[0059] Table 2 Leather glossiness and extinction rate

[0060]

[0061]

[0062] Glossiness reflects the ability to reflect light and is determined by the smoothness of the object surface. There are nanoparticles in the finishing agents of Example 1 and Comparative Example 2. Therefore, when curing into a film, a rougher surface will be formed compared to Comparative Example 1 and Comparative Example 3, showing good matte performance. At the same time, the extinction performance also improves with the increase in the dosage of mesoporous silica.

[0063] The scratch resistance of Example 1, Example 2, Example 3 and Comparative Example 2 was observed. The scratch resistance effect was judged by observing the traces on the leather surface after finger scratching, and its appearance is shown in Table 3.

[0064] Table 3 Leather finger scratch appearance

[0065]

[0066] As can be seen from Table 2 and Table 3, by combining nanoparticles with polyurethane through chemical reactions in the form of a chain extender, compared with the method of directly mixing nanoparticles into the polyurethane emulsion, the scratch resistance can be improved on the premise of ensuring a relatively high extinction rate.

[0067] The air permeability of Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 was tested. The air permeability of the leather was evaluated by a leather air permeability tester: Measure the time t (s) for 50 mL of air to pass through a 10 cm 2 specimen. The air permeability formula is as follows

[0068] V = (50 × 3600) / [10 × (t - t0)]

[0069] where V is the air permeability (mL / cm 2 ·h), t0 is the time (s) required for 50 mL of air to pass through the blank sample. The results are shown in Table 4.

[0070] Table 4 Leather air permeability

[0071]

[0072] Compared with Comparative Example 1 and Comparative Example 3, in Example 1, Example 2, Example 3, and Comparative Example 2, the mesoporous silica introduced into the finishing agent has a hollow structure, which can increase the number of free volumes inside it, providing more channels for air molecules to pass through the surface treatment layer, thus increasing the air permeability of the leather sample. However, it can also be seen from the table that the addition of mesoporous silica has a relatively small improvement in the air permeability performance of the leather sample, which is due to the relatively small proportion of mesoporous silica used as a chain extender in the finishing agent.

[0073] The above are only the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope defined by the claims.

[0074] Those not detailed in the present invention are all well-known techniques in the technical field of the present invention.

Claims

1. A preparation method of a nano-composite finishing agent for breathable and matte water-based leather, characterized in that, The steps are as follows: S1. Prepare a chain extender and an emulsifier; S2. Mix toluene diisocyanate and polytetramethylene ether glycol and react, and add the chain extender and emulsifier prepared in step S1; S3. Add deionized water and obtain the aqueous nano-composite finishing agent for leather through stirring and emulsification.

2. The preparation method of the breathable and matte nano-composite finishing agent for aqueous leather according to claim 1, characterized in that, The molar ratio of the toluene diisocyanate to the polytetramethylene ether glycol is 1-3:1-3.

3. The preparation method of the breathable and matte nano-composite finishing agent for water-based leather according to claim 1, wherein, The addition amount of the nano-particles is 1-6% of the mass of the toluene diisocyanate and the polytetramethylene ether glycol.

4. The preparation method of the breathable and matte nano-composite finishing agent for aqueous leather according to claim 1, characterized in that, The solid content of the nano-composite finishing agent for leather is 15-30%.

5. The preparation method of the breathable and matte nano-composite finishing agent for water-based leather according to claim 1, characterized in that, Both the chain extender and the emulsifier are nano-particles with a mesoporous structure.

6. The preparation method of the breathable and matte nano-composite finishing agent for aqueous leather according to claim 5, characterized in that, The nano-particles are silicon dioxide nano-particles.

7. The preparation method of the breathable and matte nano-composite finishing agent for water-based leather according to claim 6, characterized in that, Preparing the nano-particles with a mesoporous structure includes the following steps: S11. Using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer as a template agent and tetraethyl orthosilicate as a silicon source, synthesize through the sol-gel method for 24 h. The mass ratio of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer to the tetraethyl orthosilicate is 1-3:3-7; S12. Transfer the synthesis product of step S11 to a stainless steel autoclave, keep it at 100-150 °C for 24-48 h, and then calcine at a temperature of 550-700 °C to obtain silicon dioxide nano-particles with a mesoporous structure.

8. A nano-composite finishing agent for breathable and matte water-based leather, characterized in that, The nano-composite finishing agent for leather is prepared by using the preparation method described in any one of claims 1 to 7.

9. Application of a breathable and matte nano-composite finishing agent for aqueous leather as described in claim 8 in leather production, characterized in that, The leather includes a leather body and a slurry coated on the surface of the leather body. The slurry includes 5 parts of a curing agent and 100 parts of the nano-composite finishing agent for leather.

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