Aqueous silicone coating material for leather and method for its production

Abstract

This invention relates to the field of organosilicon materials, and discloses a water-based organosilicon coating material for leather and its preparation method. The water-based organosilicon coating material is divided into component A and component B. By mass, component A includes 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 5-20 parts of hydrogen-containing silicone oil, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, and 80-120 parts of deionized water. Component B includes 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, 5-20 parts of catalyst, and 80-120 parts of deionized water. The water-based organosilicon coating material for leather prepared by this invention has the characteristics of low VOC, safety and environmental protection, excellent hand feel, good stain resistance, and good adhesion.

Description

Technical Field

[0001] This invention relates to the field of organosilicon materials, specifically to an aqueous organosilicon coating material for leather and its preparation method. Background Technology

[0002] Currently, leather materials are widely used in many fields such as automobiles, aviation, bags, furniture, medical, and clothing decoration. Leather materials can be classified according to their manufacturing methods into: genuine leather, recycled leather, artificial leather, and PU synthetic leather. Among them, PU synthetic leather, due to its advantages such as a near-genuine leather appearance and texture, high strength, and lower cost, currently has an annual production capacity of 2.5 billion square meters. After tanning, PU synthetic leather requires surface treatment to improve the surface feel, adjust the surface gloss and matte finish, and enhance the customer experience. Currently, the main leather finishing material is PU surface treatment agent (i.e., PU resin). Using PU surface treatment agents can achieve ideal gloss and matte finish and improve the leather feel to some extent. However, it cannot meet people's demands for leather's skin-friendly feel and stain resistance.

[0003] To address the aforementioned technical issues, some industry research has attempted to use organosilicon materials for surface treatment of PU synthetic leather. While this effectively improves the skin-friendly feel and stain resistance of PU synthetic leather, it requires the addition of large amounts of solvents, lacking the advantages of being environmentally friendly, and also exhibits poor adhesion. Therefore, developing a water-based organosilicon coating material for leather could give PU leather a skin-friendly feel and stain resistance, while also providing good adhesion, thus showing broad application prospects. Summary of the Invention

[0004] The present invention aims to provide a water-based organosilicon coating material for leather and its preparation method, so as to solve the problems of existing organosilicon materials used for surface treatment of PU synthetic leather containing solvents, being environmentally unfriendly, and having poor adhesion to PU leather.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a water-based organosilicon coating material for leather, comprising component A and component B. By mass, component A comprises 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 5-20 parts of hydrogen-containing silicone oil, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, and 80-120 parts of deionized water; component B comprises 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, 5-20 parts of catalyst, and 80-120 parts of deionized water.

[0006] Preferably, as an improvement, the hydroxyl content of the hydroxyl-terminated polydimethylsiloxane is 0.04wt% to 0.2wt%, and the viscosity is 20,000 to 500,000 mPa·s.

[0007] Preferably, as an improvement, the polyacrylate emulsion is a self-made copolymer emulsion with methacrylate, butyl acrylate, lauryl acrylate and methacryloxypropyltriethoxysilane as monomers, and the molar ratio of methyl methacrylate, butyl acrylate, lauryl acrylate and methacryloxypropyltriethoxysilane is 60-80:10-25:7-15:1-3%.

[0008] Preferably, as an improvement, the method for preparing polyacrylate emulsion includes the following steps:

[0009] S1. Methacrylate, butyl acrylate, lauryl acrylate, methacryloxypropyltriethoxysilane, OP-10, and deionized water are pre-emulsified in a reactor, and potassium persulfate initiator is dissolved in water.

[0010] S2. Add the same proportion of pre-emulsified monomer and potassium persulfate to the reactor, heat and react. Then add the remaining pre-emulsified monomer and potassium persulfate dropwise and continue the reaction. After the reaction is complete, remove the polyacrylate emulsion under vacuum to obtain the polyacrylate emulsion.

[0011] Preferably, as an improvement, the emulsifier is a compound of polyether-modified silicone oil and auxiliary emulsifier, and the mass ratio of polyether-modified silicone oil to auxiliary emulsifier is 60-90:10-40. The auxiliary emulsifier is at least one of SDS, AEO-3, AEO-7, AEO-9, and OP-10.

[0012] Preferably, as an improvement, the leveling agent is polyether-modified silicone oil with a viscosity of 20–100 mPa·s.

[0013] Preferably, as an improvement, the polyether-modified silicone oil has the structural formula as shown in formula (I):

[0014]

[0015] Where d is an integer from 0 to 5, e is an integer from 5 to 20, f is an integer from 5 to 20, and n is an integer from 2 to 12.

[0016] Preferably, as an improvement, the hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil with a hydrogen mass fraction of 0.45% to 1.2% and a viscosity of 30 to 500 mPa·s; the catalyst is a caster platinum catalyst.

[0017] Preferably, as an improvement, a method for preparing a water-based organosilicon coating material for leather is characterized by comprising the following steps:

[0018] Step 1: Emulsify hydroxyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, emulsifier, leveling agent and deionized water in a high-speed mixer, then add polyacrylate emulsion and matting powder and stir evenly to obtain component A;

[0019] Step 2: Hydroxyl-terminated polydimethylsiloxane, catalyst, emulsifier, leveling agent and deionized water are emulsified in a high-speed mixer, and then polyacrylate emulsion and matting powder are added and stirred evenly to obtain component B;

[0020] Step 3: Mix components A and B, stir evenly, and filter to obtain water-based organosilicon coating material for leather.

[0021] Preferably, as an improvement, in step three, the mass ratio of component A to component B is 1:1.

[0022] The principle and advantages of this solution are as follows: In practical applications, this technical solution addresses the problems of existing non-silicone surface treatment agents lacking skin-friendly feel and stain-resistant properties, as well as the issues of silicone materials containing solvents and being environmentally unfriendly when used for surface treatment of PU synthetic leather, and their poor adhesion to PU leather. Focusing on silicone materials as the main research direction, the composition and preparation process of silicone coatings are systematically optimized. The silicone material is emulsified using a self-made polyether-modified silicone oil and a leveling agent, combined with an acrylate emulsion copolymerized from acrylate and silane, to prepare a water-based silicone coating material for leather. This solves the problem of silicone surface treatment agents containing solvents and being environmentally unfriendly, without affecting the strength, skin-friendly feel, and stain-resistant properties of the silicone layer, while also exhibiting good adhesion to PU leather.

[0023] During the technology research and development phase, the inventors water-based non-polar organosilicon materials, solving the solvent contamination problem. The resulting surface treatment emulsion exhibits good stability and is flawless when used for leather surface treatment. Furthermore, the self-made polyether-modified silicone oil emulsifier not only emulsifies and levels the coating but also participates in the crosslinking reaction without affecting the coating's feel or strength. The introduction of polyacrylate emulsion solved the coating's adhesion problem and improved its feel. In addition, after preparing the polyether-modified silicone oil emulsifier, the inventors further optimized the emulsion system, using a silicone-based polyether-modified silicone oil emulsifier in combination with several auxiliary emulsifiers. This solved the emulsification problem of the organosilicon component and improved compatibility with the polyacrylate component, demonstrating significant advantages. Using hydroxyl-terminated polydimethylsiloxane as the base polymer, the inventors discovered that its hydrogen content and viscosity directly affect the coating's strength and toughness. Excessive viscosity reduces hydroxyl content and decreases strength, while excessively low viscosity and shorter molecular chains reduce toughness. Optimizing the hydrogen content and viscosity allows for a balance between strength and coating toughness. Detailed Implementation

[0024] The following detailed description provides further details on specific embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials and reagents used are all commercially available.

[0025] Overview of the plan:

[0026] A water-based silicone coating material for leather includes component A and component B. By weight, component A includes 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 5-20 parts of hydrogen-containing silicone oil, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, and 80-120 parts of deionized water; component B includes 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, 5-20 parts of catalyst, and 80-120 parts of deionized water.

[0027] The hydroxyl content of the hydroxyl-terminated polydimethylsiloxane is 0.04wt% to 0.2wt%, and the viscosity (tested under standard conditions) is 20,000 to 500,000 mPa·s.

[0028] The polyacrylate emulsion is a self-made copolymer emulsion using methacrylate, butyl acrylate, lauryl acrylate, and methacryloxypropyltriethoxysilane as monomers. During feeding, the molar ratio is 60-80% methyl methacrylate, 10-25% butyl acrylate, 7-15% lauryl acrylate, and 1-3% methacryloxypropyltriethoxysilane.

[0029] The preparation method of polyacrylate emulsion is as follows: Methacrylate, butyl acrylate, lauryl acrylate, methacryloxypropyltriethoxysilane, OP-10, and deionized water are pre-emulsified in a reaction vessel, and potassium persulfate initiator is dissolved in water. Equal proportions of pre-emulsified monomers and potassium persulfate are added to the reaction vessel, and the mixture is heated to 80°C for 2 hours. The remaining pre-emulsified monomers and potassium persulfate are then added dropwise, and the reaction continues for another 8 hours. After vacuum descaling, the polyacrylate emulsion is obtained.

[0030] Hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil with a hydrogen mass fraction of 0.45% to 1.2% and a viscosity of 30 to 500 mPa·s.

[0031] The emulsifier is a compound emulsifier with polyether-modified silicone oil as the main component (60-90% by mass) and SDS, AEO-3, AEO-7, AEO-9 and OP-10 as auxiliary components (10-40% by mass).

[0032] The leveling agent is polyether-modified silicone oil with a viscosity of 20–100 mPa·s.

[0033] The structural formula of polyether-modified silicone oil is shown in formula (I):

[0034]

[0035] Where d is an integer from 0 to 5, e is an integer from 5 to 20, f is an integer from 5 to 20, and n is an integer from 2 to 12.

[0036] The catalyst is a caster-platinum catalyst.

[0037] A method for preparing a water-based organosilicon coating material for leather includes the following steps:

[0038] Step 1: Emulsify hydroxyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, emulsifier, leveling agent and deionized water in a high-speed mixer, then add polyacrylate emulsion and matting powder and stir evenly to obtain component A;

[0039] Step 2: Hydroxyl-terminated polydimethylsiloxane, catalyst, emulsifier, leveling agent and deionized water are emulsified in a high-speed mixer, and then polyacrylate emulsion and matting powder are added and stirred evenly to obtain component B;

[0040] Step 3: Mix components A and B in a mass ratio of 1:1, stir evenly, and filter out impurities to obtain a water-based organosilicon coating material for leather.

[0041] Example 1

[0042] A method for preparing a water-based organosilicon coating material for leather includes the following steps:

[0043] Step 1: Emulsify 100 parts of hydroxyl-terminated polydimethylsiloxane, 5-20 parts of hydrogen-containing silicone oil, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, and 80-120 parts of deionized water in a high-speed mixer. Then add 10-60 parts of polyacrylate emulsion and 2-15 parts of matting agent and stir evenly to obtain component A.

[0044] Step 2: Emulsify 100 parts of hydroxyl-terminated polydimethylsiloxane, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, 5-20 parts of catalyst, and 80-120 parts of deionized water in a high-speed mixer. Then add 10-60 parts of polyacrylate emulsion and 2-15 parts of matting agent and stir evenly to obtain component B.

[0045] Step 3: Mix components A and B in a mass ratio of 1:1, stir evenly, and filter out impurities to obtain a water-based organosilicon coating material for leather.

[0046] The method of using water-based silicone coating material for leather is as follows: using a gravure printing machine, the water-based silicone coating material is coated on the surface of polyurethane synthetic leather, and then cured by baking at 120-150℃ for 5-8 minutes to obtain the surface-treated polyurethane synthetic leather.

[0047] Examples 1-6 are embodiments of the present invention. The difference between each embodiment lies in the difference in the components and the amount added, as detailed in Table 1.

[0048] Table 1

[0049]

[0050]

[0051] Comparative Example 1

[0052] The difference between Comparative Example 1 and Example 6 is that no polyacrylate emulsion was added in this comparative example.

[0053] Comparative Example 2

[0054] The difference between Comparative Example 2 and Example 6 is that in this comparative example, methacryloyloxypropyltriethoxysilane is not added to the polyacrylate emulsion.

[0055] Comparative Example 3

[0056] The difference between Comparative Example 3 and Example 6 is that the self-made polyether modified silicone oil in the emulsifier and leveling agent was replaced with ordinary commercially available polyether modified silicone oil (manufacturer: Qingtian Chemical).

[0057] Comparative Example 4

[0058] The difference between Comparative Example 4 and Example 6 is that the self-made polyether modified silicone oil in the emulsifier was replaced with an equal mixture of SDS, AEO-3, AEO-7, AEO-9 and OP-10 in this comparative example.

[0059] Comparative Example 5

[0060] The difference between this comparative example and Example 6 is that the hydroxyl content of the hydroxyl-terminated polydimethylsiloxane in this comparative example is 0.02 wt%.

[0061] Comparative Example 6

[0062] The difference between this comparative example and Example 6 is that the viscosity of the hydroxyl-terminated polydimethylsiloxane in this comparative example is 18000 mPa·s.

[0063] Comparative Example 7

[0064] The difference between this comparative example and Example 6 is that the raw material composition of the polyacrylate emulsion in this comparative example is (in molar ratio) 50% methyl methacrylate, 30% butyl acrylate, 5% lauryl acrylate and 15% methacryloyloxypropyltriethoxysilane.

[0065] Experimental Performance Testing

[0066] The following performance tests were conducted on the polyurethane synthetic leather surface-treated with water-based silicone coating material in each embodiment and comparative example. The test indicators and test methods are as follows:

[0067] 1. Appearance test

[0068] Under strong light, examine the treated leather surface for any defects. The evaluation criteria are as follows:

[0069] Level 1 Flawless

[0070] Level 2 Minor Imperfections (with minor flaws)

[0071] Level 3 Major Defect (with shiny lines)

[0072] Level 4 has many flaws in appearance.

[0073] 2. Anti-fouling test

[0074] The tests were conducted according to ASTM D1308-02, using oil-based pens, chili oil, beverages, and ballpoint pens to test stain resistance. Test times were 15 min, 1 h, 2 h, 8 h, and 24 h. The evaluation criteria are as follows:

[0075] The level 1 stain was not removed at all;

[0076] The level 2 stains are almost all still there;

[0077] Level 3 minor stain;

[0078] Level 4: No residual stains.

[0079] 3. Hand feel test

[0080] Touch the treated leather surface to judge its feel; the evaluation criteria are as follows:

[0081] Level 1 smoothness;

[0082] Level 2 is relatively smooth;

[0083] Level 3 (General)

[0084] Level 4 is poor.

[0085] 4. Scratch resistance

[0086] Scratch the leather surface with a coin to check for damage to the coating. The evaluation criteria are as follows:

[0087] Level 1, no damage;

[0088] Level 2 minor damage;

[0089] Level 3 severe damage;

[0090] Level 4: Complete detachment.

[0091] 5. Bending strength

[0092] The test shall be conducted in accordance with the method specified in QB / T 2714. The flexural strength shall be tested, and the leather condition shall be observed every 5,000 cycles to see if there is any delamination or cracking on the leather surface. The highest number of flexural cycles without cracking or delamination shall be recorded, and the test shall be conducted up to 100,000 cycles.

[0093] 6. Bending strength after boiling

[0094] After boiling the leather in 85℃ hot water for 5 days, test it according to the method specified in QB / T 2714 to test its flexural strength. Observe the leather condition every 5,000 times to see if there is any powdering or cracking on the leather surface. Record the highest number of flexural cycles without cracking or powdering. Test up to 100,000 times.

[0095] 7. Bending strength after salt spray aging

[0096] After corroding the leather in a salt spray aging test chamber for 1000 hours, the test was carried out according to the method specified in QB / T 2714. The flexural strength was tested, and the leather condition was observed every 5,000 cycles to see if there was any powdering or cracking on the leather surface. The highest number of flexural cycles without cracking or delamination was recorded, and the test was carried out up to 100,000 cycles.

[0097] 8. Bending strength after UV aging

[0098] After treating the leather with a UV aging test chamber for 48 hours, the test was conducted according to the method specified in QB / T 2714. The flexural strength was tested, and the leather condition was observed every 5,000 cycles to see if there was any powdering or cracking on the leather surface. The highest number of flexural cycles without cracking or delamination was recorded, and the test was conducted up to 100,000 cycles.

[0099] The test results are shown in Table 2. From the results in Table 2, it can be seen that: Comparative Example 1, without the addition of polyacrylate emulsion, had poor adhesion, and its scratch resistance, feel, and folding strength were all poor; Comparative Example 2, without the addition of methacryloxypropyltriethoxysilane to the polyacrylate emulsion, showed decreased compatibility between the polyacrylate emulsion and the organosilicon components, and its appearance, stain resistance, and feel were not optimal; Comparative Example 3, by replacing the self-made polyether-modified silicone oil in the emulsifier and leveling agent with ordinary commercially available polyether-modified silicone oil, found that the commercially available polyether-modified silicone oil could not participate in the crosslinking reaction, affecting the coating strength and scratch resistance, and its emulsification and leveling effects were also not very good, resulting in suboptimal appearance and feel; Comparative Example 4, with the addition of self-made polyether-modified silicone oil to the emulsifier... Replacing SDS, AEO-3, AEO-7, AEO-9, and OP-10 in equal proportions with polyether-modified silicone oil resulted in poor stability of the coating material, leading to poor appearance, stain resistance, feel, and scratch resistance of the treated leather, as well as poor coating adhesion. Comparative Example 5 used silicone oil with a lower hydroxyl content, resulting in a lower crosslinking density of the coating, thus causing poor feel and scratch resistance of the treated leather. Comparative Example 6 used hydroxyl-terminated polydimethylsiloxane with a lower viscosity, reducing the toughness of the coating and resulting in poor feel and scratch resistance of the treated leather. Comparative Example 7 had a lower proportion of hard monomers in the polyacrylate emulsion, resulting in low polymer strength and poor feel and scratch resistance of the treated leather. However, the methods used in Examples 1-6 all resulted in surface treatment agents with better effects.

[0100] Table 2

[0101]

[0102] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An aqueous silicone coating material for leather, characterized by: The product comprises two components, A and B. By weight, component A includes 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 5-20 parts of hydrogen-containing silicone oil, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, and 80-120 parts of deionized water. Component B includes 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-60 parts of polyacrylate emulsion, 2-15 parts of matting agent, 2-15 parts of emulsifier, 0.2-5 parts of leveling agent, 5-20 parts of catalyst, and 80-120 parts of deionized water. The hydroxyl content of the hydroxyl-terminated polydimethylsiloxane is 0.04wt%-0.2wt%, and the viscosity is 20,000-500,000 ppm. mPa·s; the emulsifier is a compound of polyether-modified silicone oil and auxiliary emulsifier; the leveling agent is polyether-modified silicone oil; the structural formula of the polyether-modified silicone oil is as shown in formula (I): Formula (I) Where d is an integer from 0 to 5, e is an integer from 5 to 20, f is an integer from 5 to 20, and n is an integer from 2 to 12.

2. The water-based organosilicon coating material for leather according to claim 1, characterized in that: The polyacrylate emulsion is a self-made copolymer emulsion with methyl methacrylate, butyl acrylate, lauryl acrylate and methacryloxypropyltriethoxysilane as monomers, and the molar ratio of methyl methacrylate, butyl acrylate, lauryl acrylate and methacryloxypropyltriethoxysilane is 60~80:10~25:7~15:1~3%.

3. The water-based organosilicon coating material for leather according to claim 2, characterized in that: The method for preparing the polyacrylate emulsion includes the following steps: S1. Methyl methacrylate, butyl acrylate, lauryl acrylate, methacryloxypropyltriethoxysilane, OP-10, and deionized water are pre-emulsified in a reactor, and potassium persulfate initiator is dissolved in water. S2. Add the same proportion of pre-emulsified monomer and potassium persulfate to the reactor, heat and react. Then add the remaining pre-emulsified monomer and potassium persulfate dropwise and continue the reaction. After the reaction is complete, remove the polyacrylate emulsion under vacuum to obtain the polyacrylate emulsion.

4. The water-based organosilicon coating material for leather according to claim 3, characterized in that: The mass ratio of the polyether-modified silicone oil to the auxiliary emulsifier is 60~90:10~40, and the auxiliary emulsifier is at least one of SDS, AEO-3, AEO-7, AEO-9, and OP-10.

5. The water-based organosilicon coating material for leather according to claim 4, characterized in that: The viscosity of the polyether-modified silicone oil is 20~100 mPa·s.

6. A water-based organosilicon coating material for leather according to claim 5, characterized in that: The hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil with a hydrogen mass fraction of 0.45% to 1.2% and a viscosity of 30 to 500 mPa·s; the catalyst is a caster-platinum catalyst.

7. A method for preparing a water-based organosilicon coating material for leather according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Emulsify hydroxyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, emulsifier, leveling agent and deionized water in a high-speed mixer, then add polyacrylate emulsion and matting powder and stir evenly to obtain component A; Step 2: Hydroxyl-terminated polydimethylsiloxane, catalyst, emulsifier, leveling agent and deionized water are emulsified in a high-speed mixer, and then polyacrylate emulsion and matting powder are added and stirred evenly to obtain component B; Step 3: Mix components A and B, stir evenly, and filter to obtain water-based organosilicon coating material for leather.

8. The method for preparing a water-based organosilicon coating material for leather according to claim 7, characterized in that: In step three, the mass ratio of component A to component B is 1:1.

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