Preparation method of liquid leather coating

Abstract

The invention provides a preparation method of a liquid leather coating. The liquid leather coating comprises a moisture absorption coating and a hydrophobic coating, the tear resistance of the coating is improved by adding short-chain polylactic acid, collagen fibers and ethyoxyl diethylene glycol and adopting an infrared heating curing mode; by using collagen fibers, ethyoxyl diglycol and chitosan, the water absorption performance of the coating is improved; the microporous coating is prepared by adding lauryl sodium sulfate, and the air permeability of the coating is improved by increasing the content of DMF (Dimethyl Formamide) by using phase change microspheres; by using the phase change microspheres, the coating has the effects of being warm in winter and cool in summer; the hydrophobic property of the coating is improved through surface hydrophobic modification and staged impregnation.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly to a preparation method of a liquid leather coating. Background Art

[0002] After years of development, artificial leather coating materials have formed a technical system mainly based on polyurethane (PU) and polyvinyl chloride (PVC), and have been widely used in the fields of clothing, shoe materials, luggage, etc. However, with the upgrading of consumption and the emergence of emerging application scenarios, the limitations of traditional coating materials in performance have become increasingly prominent.

[0003] Air permeability is a key indicator affecting wearing comfort. Currently, the air permeability of commercially available ordinary PU coating materials is generally low, resulting in the inability to discharge sweat in time and causing a stuffy feeling when wearing.

[0004] In terms of mechanical properties, the tear strength of traditional coating materials is insufficient. Taking the application of car seats as an example, the industry standard requires a tear strength of at least 25 N / mm, which means that existing materials often need to be specially treated or thickened to meet the requirements.

[0005] Poor environmental adaptability, lack of temperature responsiveness, and inability to achieve dynamic air permeability adjustment under the temperature difference between winter and summer.

[0006] Poor multi-functional integration. Artificial leather products can only meet basic appearance and waterproof requirements, and cannot achieve the unified coordination of hydrophilicity, hydrophobicity, and air permeability. Especially in the field of medical protection, products that require both waterproof and anti-fouling properties and good air permeability are extremely scarce.

[0007] Researchers have tried to improve the performance of artificial leather coatings through various methods, and gradually developed liquid leather technology, which simulates the multi-layer structure and dynamic characteristics of the human skin to develop a new generation of functional coating materials. Liquid leather coating materials are mainly based on silicon-based material systems and polyurethane systems. However, silicon-based materials also face the problem of insufficient mechanical strength, and the polyurethane system faces the problem of poor hydrophilicity.

[0008] Therefore, there is an urgent need to develop a multi-functional liquid leather coating with hydrophilicity, air permeability, dynamic temperature regulation, and tear resistance. Summary of the Invention

[0009] In order to solve the above problems, the present invention provides a preparation method of a liquid leather coating, which is characterized by including the following steps:

[0010] Step S1, preparing a mixed solution A: dispersing chitosan, collagen fibers, short-chain polylactic acid, maltose, and ethoxydiglycol in water to form a mixed solution A;

[0011] Step S2, homogenously prepare microbubble liquid C: Add sodium dodecyl sulfate to the mixed liquid A to make mixed liquid B, and homogenize to generate microbubbles in the mixed liquid B to make microbubble liquid C;

[0012] Step S3, prepare microporous coating D: Coat the microbubble liquid C in a mold and dry it to make microporous coating D;

[0013] Step S4, glyoxal impregnation: Immerse the microporous coating D in a glyoxal solution for crosslinking reaction to make coating E;

[0014] Step S5, coating roughening: Grind coating E to roughen the surface of coating E, expose the collagen fiber villi, and take out the coating from the mold, which is the moisture-absorbing coating;

[0015] Step S6, prepare mixed liquid F: Disperse polyurethane resin, acrylic resin, sorbitol, salicylic acid ester, and phase change microspheres in dimethylformamide to make mixed liquid F;

[0016] Step S7, magnetic mapping: Add neodymium iron boron pigment to the mixed liquid F, mix evenly to make mixed liquid G; Coat the mixed liquid G in a mold, and then place it in a magnetic field. Under the guidance of the magnetic field, the neodymium iron boron pigment automatically forms a pattern to make the magnetized pattern layer H;

[0017] Step S8, infrared heating pre-curing: Pre-cure the magnetized pattern layer H by infrared heating to make coating I;

[0018] Step S9, water bath washing to remove dimethylformamide: Place coating I in water and wash to remove dimethylformamide to make the breathable coating J;

[0019] Step S10, infrared heating secondary curing: Cure the breathable coating J by infrared heating to make coating K;

[0020] Step S11, 3-aminopropyltriethoxyperfluorohexylsilane impregnation: Dissolve 3-aminopropyltriethoxyperfluorohexylsilane in dimethylformamide to make solution L; Immerse coating K in solution L to make coating M;

[0021] Step S12, prepare hydrophobic coating: Carry out surface modification reaction on coating M to make coating N; Wash coating N with water to remove dimethylformamide, which is the hydrophobic coating;

[0022] Step S13, prepare liquid skin coating: Use an adhesive to bond the opposite side of the pattern surface of the hydrophobic coating to the opposite side of the villus surface of the moisture-absorbing coating to make the liquid skin coating; The adhesive is acrylate.

[0023] As a preferred technical solution, in step S1, the molecular weight of chitosan is 100KDa - 200KDa, and the degree of deacetylation is 90% - 100%; the mass concentration of chitosan in solution A is 3% - 5%; the mass concentration of collagen fibers in solution A is 0.1% - 0.3%; the mass concentration of short-chain polylactic acid in solution A is 5% - 7%; the mass concentration of maltose in solution A is 1% - 3%; the mass concentration of ethoxydiglycol in solution A is 0.1% - 0.3%.

[0024] As a preferred technical solution, in step S2, the mass concentration of sodium dodecyl sulfate in solution B is 1% - 4%.

[0025] As a preferred technical solution, in step S3, the thickness of the microporous coating D is 20μm - 40μm; the drying temperature is 50°C - 60°C.

[0026] As a preferred technical solution, in step S4, the mass concentration of the glyoxal solution is 4% - 6%, and the solvent is ethanol; the cross-linking reaction time is 10 hours - 20 hours, and the cross-linking reaction temperature is 20°C - 30°C.

[0027] As a preferred technical solution, in step S6, the mass concentration of polyurethane resin in the mixed solution F is 20% - 30%; the mass concentration of acrylic resin in solution F is 20% - 30%; the mass concentration of sorbitol in solution F is 5% - 6%; the mass concentration of salicylate in solution F is 5% - 6%; the mass concentration of phase change microspheres in solution F is 2% - 3%; the diameter of the phase change microspheres is 1μm - 5μm; the shell of the phase change microspheres is acrylonitrile copolymer, and the inside of the phase change microspheres is isobutane.

[0028] As a preferred technical solution, in step S7, the mass concentration of neodymium iron boron pigment in the mixed solution G is 5% - 10%; the magnetic field strength is 1.5T - 2.5T, and the coating thickness is 100μm - 150μm.

[0029] As a preferred technical solution, in step S8, the infrared wavelength is 1μm - 3μm, the pre-curing temperature is 30°C - 40°C; the pre-curing time is 20 hours - 24 hours.

[0030] As a preferred technical solution, in step S10, the infrared wavelength is 1μm - 3μm, the curing temperature is 50°C - 60°C; the curing time is 1 hour - 2 hours; the thickness of the coating K is 20μm - 40μm.

[0031] As a preferred technical solution, in the step S11, the mass concentration of 3-aminopropyltriethoxyperfluorohexylsilane in the solution L is 2% to 4%; the impregnation is divided into a first-stage impregnation and a second-stage impregnation; the temperature of the first-stage impregnation is 0°C to 2°C, and the time of the first-stage impregnation is 2 hours to 4 hours; the temperature of the second-stage impregnation is 60°C to 70°C, and the time of the second-stage impregnation is 1 hour to 2 hours.

[0032] As a preferred technical solution, in the step S12, the surface modification reaction temperature is 80°C to 100°C; the surface modification reaction time is 1 hour to 2 hours.

[0033] Natural chitosan and collagen fibers have good affinity with human tissues. The present invention uses natural chitosan and collagen fibers to simulate the skin, which has good hydrophilic properties and texture experience.

[0034] In the present invention, by grinding the coating E, the surface of the coating E is roughened to expose the collagen fiber villi, further simulating the skin and enhancing the contact texture.

[0035] Through the above technical solutions, the present invention has the following technical effects:

[0036] (1) Improve the tear resistance of the coating by the curing method of short-chain polylactic acid, collagen fibers, ethoxydiglycol, and infrared heating.

[0037] (2) Improve the water absorption of the coating by collagen fibers, ethoxydiglycol, and chitosan.

[0038] (3) Prepare a microporous coating by adding sodium dodecyl sulfate, and increase the air permeability of the coating by using phase change microspheres and increasing the DMF content.

[0039] (4) Make the coating have the function of keeping warm in winter and cool in summer by using phase change microspheres.

[0040] (5) Improve the hydrophobic property of the coating by surface hydrophobic modification reaction and staged impregnation.

[0041] (6) The liquid skin coating includes a moisture-absorbing coating and a hydrophobic coating; when used as a fabric, the moisture-absorbing coating faces the skin side, which can quickly absorb the sweat and moisture of the body, keeping the skin dry; the moisture of the moisture-absorbing coating diffuses to the hydrophobic coating in the form of water vapor and volatilizes; when the skin is dry, the moisture-absorbing coating releases moisture to avoid excessive dryness of the skin and keep it moist; the hydrophobic coating faces the outside, which can produce a waterproof and moisture-proof effect.

[0042] (7) By magnetic mapping, the neodymium iron boron pigment automatically forms a pattern, which is quick and convenient compared with methods such as printing and dyeing. Detailed implementation manners

[0043] To make the above objects, features and advantages of the present invention more obvious and understandable, the applicant will illustrate and analyze through specific test examples and embodiments.

[0044] Test Example 1

[0045] Step S1, preparing mixed solution A: Dispersing chitosan, collagen fiber, short-chain polylactic acid, maltose, and ethoxydiglycol in water to make mixed solution A; the molecular weight of the chitosan is 100KDa, and the degree of deacetylation is 90%; the mass concentration of the chitosan in solution A is 3%; the mass concentration of the collagen fiber in solution A is 0.1%; the mass concentration of the short-chain polylactic acid in solution A is 5%; the mass concentration of the maltose in solution A is 1%; the mass concentration of the ethoxydiglycol in solution A is 0.1%;

[0046] Step S2, homogenizing to prepare microbubble solution C: Adding sodium dodecyl sulfate to mixed solution A to make mixed solution B, and homogenizing to generate microbubbles in mixed solution B to make microbubble solution C; the mass concentration of the sodium dodecyl sulfate in solution B is 1%;

[0047] Step S3, preparing microporous coating D: Coating microbubble solution C on a mold and drying to make microporous coating D; the thickness of the microporous coating D is 20μm; the drying temperature is 50°C;

[0048] Step S4, glyoxal impregnation: Immersing microporous coating D in a glyoxal solution for cross-linking reaction to make coating E; the mass concentration of the glyoxal solution is 4%, and the solvent is ethanol; the cross-linking reaction time is 10 hours, and the cross-linking reaction temperature is 20°C;

[0049] Step S5, coating roughening: Grinding coating E to roughen the surface of coating E, exposing the collagen fiber fluff, and taking out the coating from the mold to obtain the moisture-absorbing coating.

[0050] Test Example 2, using lactic acid instead of short-chain polylactic acid, and other parameters are the same as those in Test Example 1.

[0051] Test Example 3, without using collagen fiber, and other parameters are the same as those in Test Example 1.

[0052] Test Example 4, without using ethoxydiglycol, and other parameters are the same as those in Test Example 1.

[0053] Test Example 5, using polyurethane instead of chitosan, and its mass concentration in solution A is 20%, and other parameters are the same as those in Test Example 1.

[0054] Test Example 6, without performing Step S2, and no longer adding sodium dodecyl sulfate to mixed solution A; in Step S3, directly coating mixed solution A on a mold, and other parameters and steps are the same as those in Test Example 1.

[0055] Test Example 1

[0056] Test the tear resistance of the moisture-absorbing coatings in Test Examples 1 to 4 in accordance with GB / T 16578.2-2009 Plastics - Films and sheeting - Determination of tear resistance - Elmendorf method.

[0057] The test results are shown in the following table. It can be seen from the table that short-chain polylactic acid, collagen fiber, and ethoxydiglycol can all improve the tear resistance of the coating.

[0058] Short-chain polylactic acid is a polymer formed by the polymerization of lactic acid monomers. Short-chain polylactic acid forms a cross-linked structure through chemical reactions with other components (such as chitosan). This cross-linking can further improve the tear resistance of the coating. However, the cross-linking ability of lactic acid monomers is weak and cannot improve the tear resistance.

[0059] In the coating, collagen fibers can act as reinforcing fibers, similar to the fiber-reinforced phase in composites. The presence of fibers can significantly improve the tear strength of the coating because it can bear part of the stress during the tearing process and prevent the propagation of cracks.

[0060] Ethoxydiglycol has high reactivity and can react with functional groups in the coating (such as the amino group of chitosan) to form chemical bonds. This cross-linking effect can increase the cross-linking density of the coating, form a more compact network structure, and thus improve the tear resistance of the coating.

[0061] Table 1: Test results of the tear resistance of the moisture-absorbing coatings in Test Examples 1 to 4

[0062] Sample Name Treatment Conditions Tear Strength (N / mm) Test Example 1 / 26 Test Example 2 Lactic Acid Instead of Short-chain Polylactic Acid 17 Test Example 3 Without Using Collagen Fibers 18 Test Example 4 Without Using Ethoxydiglycol 20

[0063] Test Example 2

[0064] Refer to GB / T 1034-2008 Determination of water absorption to test the water absorption properties of the moisture-absorbing coatings in Test Examples 1, 3 to 5.

[0065] The test results are shown in the following table. It can be seen from the table that collagen fiber, ethoxydiglycol, and chitosan can all improve the water absorption properties of the coating.

[0066] Table 2: Test results of the water absorption properties of the moisture-absorbing coatings in Test Examples 1, 3 to 5

[0067] Sample Name Treatment Conditions <![CDATA[Water absorption (g / m 2 )]]> Test Example 1 / 13 Test Example 3 Without Using Collagen Fibers 8 Test Example 4 Without Using Ethoxydiglycol 11 Test Example 5 Using Polyurethane Instead of Chitosan 6

[0068] Collagen fibers are a kind of natural biopolymer material. It has a large number of hydrophilic groups, such as amino groups and carboxyl groups, etc. These hydrophilic groups can form hydrogen bonds with water molecules, thereby adsorbing water molecules. In the coating system, the presence of collagen fibers increases the moisture absorption sites inside the coating. When the coating comes into contact with water, water molecules will preferentially interact with the hydrophilic groups on the collagen fibers and be adsorbed on the fiber surface, thus improving the water absorption performance of the coating.

[0069] Chitosan molecules contain a large number of amino groups (-NH2) and hydroxyl groups (-OH), and these functional groups are all hydrophilic. Amino groups can enhance the interaction with water molecules through protonation (-NH3 + ) and hydroxyl groups can directly form hydrogen bonds with water molecules. In the coating, the hydrophilic groups on the chitosan molecular chain will adsorb water molecules in the surrounding environment, thus improving the water absorption performance of the coating.

[0070] Ethoxydiglycol molecules contain multiple hydroxyl groups (-OH), and hydroxyl groups are hydrophilic groups that can form hydrogen bonds with water molecules. Ethoxydiglycol can adsorb water molecules through its hydroxyl groups in the coating, thus improving the water absorption performance.

[0071] Detection Example 3

[0072] Refer to GB / T 1038 - 2000 "Test Method for Gas Permeability of Plastic Films and Sheets - Differential Pressure Method" to determine the gas permeability of the moisture-absorbing coatings in Test Example 1 and Test Example 6.

[0073] The test results are shown in the following table. In Test Example 1, microbubble liquid C was prepared by homogenization and coated to form microporous coating D, and there are a large number of tiny pores generated by microbubbles inside the coating. These pores provide more permeation channels for air, making it easier for gas to pass through the coating, thus improving the gas permeability of the coating.

[0074] In Test Example 6, sodium dodecyl sulfate was not added, no microbubble liquid was prepared, and there is no tiny pore structure generated by microbubbles. The inside of the coating is denser, and the resistance to gas permeation is greater, resulting in a decrease in the gas permeability rate.

[0075] Table 3: Detection Results of Gas Permeability Rates of Moisture-Absorbing Coatings in Test Examples 1 and 6

[0076] Sample Name Treatment Conditions <![CDATA[Air permeability [cm 3 / (m 2 *24h*Pa)]]> Test Example 1 Adding Sodium Dodecyl Sulfate 255 Test Example 6 Without Adding Sodium Dodecyl Sulfate 121

[0077] Test Example 7

[0078] Step S6, Preparation of mixture F: Polyurethane resin, acrylic resin, sorbitol, salicylate, and phase change microspheres are dispersed in dimethylformamide to form mixture F; the mass concentration of polyurethane resin in mixture F is 20%; the mass concentration of acrylic resin in solution F is 20%; the mass concentration of sorbitol in solution F is 5%; the mass concentration of salicylate in solution F is 5%; the mass concentration of phase change microspheres in solution F is 2%; the diameter of the phase change microspheres is 1 μm; the shell of the phase change microspheres is acrylonitrile copolymer, and the inside of the phase change microspheres is isobutane;

[0079] Step S7, Magnetic force mapping: Neodymium iron boron pigment is added to mixture F and mixed evenly to form mixture G; mixture G is coated in a mold and then placed in a magnetic field. Under the guidance of the magnetic field, the neodymium iron boron pigment automatically forms a pattern to form a magnetized pattern layer H; the mass concentration of neodymium iron boron pigment in mixture G is 5%; the magnetic field strength is 1.5 T, and the coating thickness is 100 μm;

[0080] Step S8, Infrared heating pre-curing: The magnetized pattern layer H is pre-cured by infrared heating to form a coating I; the infrared wavelength is 1 μm, the pre-curing temperature is 30 °C; the pre-curing time is 20 hours;

[0081] Step S9, Water bath washing to remove dimethylformamide: Coating I is placed in water and washed to remove dimethylformamide to form a breathable coating J;

[0082] Step S10, Infrared heating secondary curing: The breathable coating J is cured by infrared heating to form a coating K; the infrared wavelength is 1 μm, the curing temperature is 50 °C; the curing time is 1 hour; the thickness of coating K is 20 μm;

[0083] Step S11, Impregnation with 3-aminopropyltriethoxyperfluorohexylsilane: 3-aminopropyltriethoxyperfluorohexylsilane is dissolved in dimethylformamide to form solution L; coating K is impregnated in solution L to form coating M; the mass concentration of 3-aminopropyltriethoxyperfluorohexylsilane in solution L is 2%; the impregnation is divided into a first-stage impregnation and a second-stage impregnation; the temperature of the first-stage impregnation is 0 °C, and the time of the first-stage impregnation is 2 hours; the temperature of the second-stage impregnation is 60 °C, and the time of the second-stage impregnation is 1 hour;

[0084] Step S12, Preparation of hydrophobic coating: Coating M is subjected to a surface modification reaction to form coating N; the temperature of the surface modification reaction is 80 °C; the time of the surface modification reaction is 1 hour; wash with water to remove dimethylformamide in coating N, which is the hydrophobic coating.

[0085] Test example 8, The mixture F does not contain phase change microspheres, and other parameters and steps are the same as those in test example 7.

[0086] Test Example 9: The usage amount of the solvent dimethylformamide in the mixed solution F was reduced by 20%, and the addition amounts of other solutes remained unchanged, that is, the solute concentration increased. Except for this, other parameters and steps were the same as those in Test Example 7.

[0087] Test Example 10: In step S8, the infrared heating temperature was 60 °C; in step S10, the infrared heating temperature was 100 °C; other parameters and steps were the same as those in Test Example 7.

[0088] Test Example 11: In step S8 and step S10, heating with a heating furnace was used instead of infrared heating, and other parameters and steps were the same as those in Test Example 7.

[0089] Test Example 12: Steps S11 and S12 of the surface modification reaction were not carried out, and the coating K was directly washed with water to form a coating; other parameters and steps were the same as those in Test Example 7.

[0090] Test Example 13: The first-stage impregnation in step S11 was not carried out; other parameters and steps were the same as those in Test Example 7.

[0091] Detection Example 4

[0092] Referring to GB / T 1038-2000 "Test Method for Gas Permeability of Plastic Films and Sheets - Differential Pressure Method", the gas permeability of the hydrophobic coating in Test Example 7 was measured respectively under the conditions of 0 ± 2 °C and 60 ± 2 °C.

[0093] Referring to GB / T 1038-2000 "Test Method for Gas Permeability of Plastic Films and Sheets - Differential Pressure Method", the gas permeability of the hydrophobic coatings in Test Example 7, Test Example 8, Test Example 9, and Test Example 10 was measured under the condition of 23 ± 2 °C.

[0094] The test results are shown in the following table. Using phase change microspheres and increasing the DMF content can both improve the gas permeability of the coating.

[0095] Table 4: Detection Results of the Gas Permeability Rate of the Hydrophobic Coatings in Test Examples 7 - 10

[0096]

[0097] Adding phase change microspheres to the coating forms microcavities between the microspheres, improving the gas permeability rate of the coating. Just like embedding multiple balloons in a dense sponge, although the expansion of the balloons squeezes some small holes in the sponge, the pores between the balloons increase the gas permeation path.

[0098] When the DMF content increases and the polymer solute concentration decreases, the distance between polymer chains increases and the porosity increases. After washing away DMF with water, more and larger connected pores are formed, improving the gas permeability rate.

[0099] Another function of using phase change microspheres is that the air permeability changes with temperature. The phase change microspheres contain isobutane, which expands significantly when the temperature > 50°C. In Test Example 7 during infrared heating and pre-curing, when the temperature is less than 50°C, the isobutane inside the microspheres presents a gas-liquid equilibrium state. At this time, the microspheres are neither in a larger state nor in a smaller state, but of a moderate size. When the temperature changes, the microspheres in the coating can become larger or smaller. When the temperature is relatively high, for example, greater than 50°C, the microspheres expand significantly, the pores between the microspheres increase, and the air permeability increases; when the temperature is relatively low, for example, 0°C, the microspheres shrink, the pores between the microspheres shrink, and the air permeability decreases. When the coating is used as a clothing material, the air permeability increases at higher temperatures, which can improve the body temperature diffusion efficiency, promote heat dissipation, and enhance comfort. When the temperature is low, the air permeability decreases, which can reduce the temperature diffusion efficiency, play a warming role, and also enhance comfort, playing the role of keeping warm in cold weather and dissipating heat in hot weather.

[0100] In Test Example 10 during infrared heating and pre-curing, the temperature is greater than 50°C, and the isobutane inside the microspheres presents a gaseous state. The microspheres are already in a larger state when they are fixed. When the prepared coating is used at a relatively high temperature, the proportion of the microspheres continuing to become larger is very small, the change in air permeability is very small, and it cannot play the role of keeping warm in winter and cool in summer.

[0101] Detection Example 5

[0102] In accordance with GB / T 16578.2-2009 "Plastics - Films and Sheeting - Determination of Tear Resistance: Elmendorf Method", the tear resistance of the hydrophobic coatings in Test Example 7 and Test Example 11 was detected.

[0103] The test results are shown in the following table. It can be seen from the table that the infrared heating method can improve the tear resistance of the coating.

[0104] Table 5: Detection Results of the Tear Resistance of the Hydrophobic Coatings in Test Example 7 and Test Example 11

[0105] Sample Name Treatment Conditions Tear Strength (N / mm) Test Example 7 / 16 Test Example 11 Heating in a Furnace 11

[0106] The infrared heating wavelength can accurately excite the vibration of the C-H bonds in the polymer chain, promote the local cross-linking of polyurethane / acrylic resin, synchronously cure the surface layer and the interior, form a more uniform cross-linked structure, and improve the tear strength of the coating.

[0107] Hot air convection heating results in a relatively large temperature difference between the inside and outside of the coating. The outer layer is over-cross-linked, the brittleness increases, and the inner layer is under-cross-linked, resulting in a decrease in tear strength.

[0108] Detection Example 6

[0109] With reference to GB / T 30693-2014 "Plastics - Determination of Water Contact Angle of Films", the contact angles of the hydrophobic coatings in Test Example 7, Test Example 12, and Test Example 13 were measured respectively to evaluate their hydrophobic properties.

[0110] The test results are shown in the following table. It can be seen from the table that both the surface modification reaction and the staged impregnation can improve the hydrophobic performance of the coating.

[0111] Table 6: Test results of the hydrophobic performance of the hydrophobic coatings in Test Example 7, Test Example 12, and Test Example 13

[0112] Sample Name Treatment Conditions Contact Angle (degrees) Test Example 7 / 122 Test Example 12 Without Surface Modification Reaction 74 Test Example 13 Without First-stage Impregnation 101

[0113] The amino group in 3-aminopropyltriethoxyperfluorohexylsilane condenses with the hydroxyl group in the coating, covering the surface of the coating with perfluorohexyl groups. By utilizing the superhydrophobic characteristics of perfluorohexyl groups, the coating is given hydrophobic characteristics.

[0114] 3-aminopropyltriethoxyperfluorohexylsilane penetrates into the pores of the coating and reacts with the coating material for hydrophobic surface modification. However, at a fixed temperature, the pore structure of the coating is relatively fixed, resulting in the incomplete immersion of 3-aminopropyltriethoxyperfluorohexylsilane into all pores. At different temperatures, the swelling volume of the phase change microspheres is different, causing changes in the microscopic pore structure of the coating and exposing the originally closed pore structure. The present invention utilizes this characteristic to impregnate 3-aminopropyltriethoxyperfluorohexylsilane at different temperatures, enabling 3-aminopropyltriethoxyperfluorohexylsilane to uniformly penetrate into the microscopic pores of the coating, making the hydrophobic modification of the coating more uniform and reducing omissions. Therefore, the hydrophobicity of the coating is further improved.

[0115] Example 1

[0116] Step S1, prepare the mixed solution A: Dispersed chitosan, collagen fibers, short-chain polylactic acid, maltose, and ethoxydiglycol in water to form the mixed solution A; the molecular weight of the chitosan is 100KDa, and the degree of deacetylation is 90%; the mass concentration of the chitosan in the solution A is 3%; the mass concentration of the collagen fibers in the solution A is 0.1%; the mass concentration of the short-chain polylactic acid in the solution A is 5%; the mass concentration of the maltose in the solution A is 1%; the mass concentration of the ethoxydiglycol in the solution A is 0.1%;

[0117] Step S2, homogenize to prepare the microbubble solution C: Add sodium dodecyl sulfate to the mixed solution A to form the mixed solution B, and homogenize to generate microbubbles in the mixed solution B to form the microbubble solution C; the mass concentration of the sodium dodecyl sulfate in the solution B is 1%;

[0118] Step S3, prepare the microporous coating D: Coat the microbubble solution C in a mold and dry it to form the microporous coating D; the thickness of the microporous coating D is 20μm; the drying temperature is 50°C;

[0119] Step S4, Glyoxal Impregnation: Immerse the microporous coating D in a glyoxal solution for crosslinking reaction to form coating E; the mass concentration of the glyoxal solution is 4%, and the solvent is ethanol; the crosslinking reaction time is 10 hours, and the crosslinking reaction temperature is 20°C;

[0120] Step S5, Coating Roughening: Grind coating E to roughen the surface of coating E, expose the collagen fiber villi, and take out the coating from the mold to obtain the moisture-absorbing coating;

[0121] Step S6, Preparation of Mixture F: Disperse polyurethane resin, acrylic resin, sorbitol, salicylic acid ester, and phase change microspheres in dimethylformamide to form mixture F; the mass concentration of polyurethane resin in mixture F is 20%; the mass concentration of acrylic resin in solution F is 20%; the mass concentration of sorbitol in solution F is 5%; the mass concentration of salicylic acid ester in solution F is 5%; the mass concentration of phase change microspheres in solution F is 2%; the diameter of the phase change microspheres is 1μm; the shell of the phase change microspheres is acrylonitrile copolymer, and the inside of the phase change microspheres is isobutane;

[0122] Step S7, Magnetic Field Mapping: Add neodymium iron boron pigment to mixture F and mix evenly to form mixture G; coat mixture G in a mold, and then place it in a magnetic field. Under the guidance of the magnetic field, the neodymium iron boron pigment automatically forms a pattern to obtain the magnetized pattern layer H; the mass concentration of neodymium iron boron pigment in mixture G is 5%; the magnetic field strength is 1.5T, and the coating thickness is 100μm;

[0123] Step S8, Infrared Heating Pre-Curing: Pre-cure the magnetized pattern layer H by infrared heating to obtain coating I; the infrared wavelength is 1μm, the pre-curing temperature is 30°C; the pre-curing time is 20 hours;

[0124] Step S9, Water Bath Washing to Remove Dimethylformamide: Place coating I in water and wash to remove dimethylformamide to obtain the breathable coating J;

[0125] Step S10, Infrared Heating Secondary Curing: Cure the breathable coating J by infrared heating to obtain coating K; the infrared wavelength is 1μm, the curing temperature is 50°C; the curing time is 1 hour; the thickness of coating K is 20μm;

[0126] Step S11, 3-Aminopropyltriethoxyperfluorohexylsilane Impregnation: Dissolve 3-aminopropyltriethoxyperfluorohexylsilane in dimethylformamide to form solution L; immerse coating K in solution L to obtain coating M; the mass concentration of 3-aminopropyltriethoxyperfluorohexylsilane in solution L is 2%; the impregnation is divided into the first-stage impregnation and the second-stage impregnation; the temperature of the first-stage impregnation is 0°C, and the time of the first-stage impregnation is 2 hours; the temperature of the second-stage impregnation is 60°C, and the time of the second-stage impregnation is 1 hour;

[0127] Step S12, preparing a hydrophobic coating: Subjecting coating M to a surface modification reaction to form coating N; the temperature of the surface modification reaction is 80 °C; the time of the surface modification reaction is 1 hour; washing with water to remove dimethylformamide in coating N, which is the hydrophobic coating;

[0128] Step S13, preparing a liquid leather coating: Using an adhesive to bond the opposite side of the patterned side of the hydrophobic coating to the opposite side of the villous surface of the moisture-absorbing coating to form a liquid leather coating; the adhesive is acrylate.

[0129] Example 2

[0130] Step S1, preparing a mixed solution A: Dispersing chitosan, collagen fibers, short-chain polylactic acid, maltose, and ethoxydiglycol in water to form a mixed solution A; the molecular weight of the chitosan is 150 KDa, and the degree of deacetylation is 95%; the mass concentration of the chitosan in solution A is 4%; the mass concentration of the collagen fibers in solution A is 0.2%; the mass concentration of the short-chain polylactic acid in solution A is 6%; the mass concentration of the maltose in solution A is 2%; the mass concentration of the ethoxydiglycol in solution A is 0.2%;

[0131] Step S2, homogenizing to prepare a microbubble solution C: Adding sodium dodecyl sulfate to the mixed solution A to form a mixed solution B, and homogenizing to generate microbubbles in the mixed solution B to form a microbubble solution C; the mass concentration of the sodium dodecyl sulfate in solution B is 3%;

[0132] Step S3, preparing a microporous coating D: Coating the microbubble solution C in a mold and drying to form a microporous coating D; the thickness of the microporous coating D is 20 μm; the drying temperature is 55 °C;

[0133] Step S4, glyoxal impregnation: Impregnating the microporous coating D in a glyoxal solution to carry out a cross-linking reaction to form a coating E; the mass concentration of the glyoxal solution is 5%, and the solvent is ethanol; the cross-linking reaction time is 15 hours, and the cross-linking reaction temperature is 25 °C;

[0134] Step S5, coating roughening: Grinding the coating E to roughen the surface of the coating E and expose the collagen fiber villi, and taking out the coating from the mold, which is the moisture-absorbing coating;

[0135] Step S6, preparation of mixture F: Disperse polyurethane resin, acrylic resin, sorbitol, salicylate, and phase change microspheres in dimethylformamide to form mixture F; the mass concentration of polyurethane resin in mixture F is 25%; the mass concentration of acrylic resin in solution F is 25%; the mass concentration of sorbitol in solution F is 5.5%; the mass concentration of salicylate in solution F is 5.5%; the mass concentration of phase change microspheres in solution F is 2.5%; the diameter of the phase change microspheres is 1 μm; the shell of the phase change microspheres is acrylonitrile copolymer, and the inside of the phase change microspheres is isobutane;

[0136] Step S7, magnetic force mapping: Add neodymium iron boron pigment to mixture F, mix evenly to form mixture G; coat mixture G in a mold, and then place it in a magnetic field. Under the guidance of the magnetic field, the neodymium iron boron pigment automatically forms a pattern to make a magnetized pattern layer H; the mass concentration of neodymium iron boron pigment in mixture G is 8%; the magnetic field strength is 2.0 T, and the coating thickness is 100 μm,

[0137] Step S8, infrared heating pre-curing: Pre-cure the magnetized pattern layer H by infrared heating to make a coating I; the infrared wavelength is 2 μm, the pre-curing temperature is 35 °C; the pre-curing time is 22 hours;

[0138] Step S9, water bath washing to remove dimethylformamide: Place coating I in water and wash to remove dimethylformamide to make a breathable coating J;

[0139] Step S10, infrared heating: Cure the breathable coating J by infrared heating to make a coating K; the infrared wavelength is 2 μm, the curing temperature is 55 °C; the curing time is 1.5 hours; the thickness of coating K is 20 μm;

[0140] Step S11, impregnation with 3-aminopropyltriethoxy perfluorohexylsilane: Dissolve 3-aminopropyltriethoxy perfluorohexylsilane in dimethylformamide to form solution L; immerse coating K in solution L to make coating M; the mass concentration of 3-aminopropyltriethoxy perfluorohexylsilane in solution L is 3%; the impregnation is divided into the first-stage impregnation and the second-stage impregnation; the temperature of the first-stage impregnation is 1 °C, and the time of the first-stage impregnation is 3 hours; the temperature of the second-stage impregnation is 65 °C, and the time of the second-stage impregnation is 1.5 hours;

[0141] Step S12, preparation of hydrophobic coating: Carry out surface modification reaction on coating M to make coating N; the temperature of the surface modification reaction is 90 °C; the time of the surface modification reaction is 1.5 hours; wash with water to remove dimethylformamide in coating N, which is the hydrophobic coating;

[0142] Step S13, preparing a liquid skin coating: Using an adhesive, bond the opposite side of the hydrophobic coating pattern side to the opposite side of the moisture-absorbing coating fluff side to form a liquid skin coating; the adhesive is acrylate.

[0143] Example 3

[0144] Step S1, preparing a mixed solution A: Disperse chitosan, collagen fibers, short-chain polylactic acid, maltose, and ethoxydiglycol in water to form a mixed solution A; the molecular weight of the chitosan is 200KDa, and the deacetylation degree is 99%; the mass concentration of the chitosan in solution A is 5%; the mass concentration of collagen fibers in solution A is 0.3%; the mass concentration of short-chain polylactic acid in solution A is 7%; the mass concentration of maltose in solution A is 3%; the mass concentration of the ethoxydiglycol in solution A is 0.3%;

[0145] Step S2, homogenizing to prepare a microbubble solution C: Add sodium dodecyl sulfate to the mixed solution A to form a mixed solution B, and homogenize to generate microbubbles in the mixed solution B to form a microbubble solution C; the mass concentration of the sodium dodecyl sulfate in solution B is 4%;

[0146] Step S3, preparing a microporous coating D: Coat the microbubble solution C in a mold and dry it to form a microporous coating D; the thickness of the microporous coating D is 20μm; the drying temperature is 60°C;

[0147] Step S4, glyoxal impregnation: Immerse the microporous coating D in a glyoxal solution for cross-linking reaction to form a coating E; the mass concentration of the glyoxal solution is 6%, and the solvent is ethanol; the cross-linking reaction time is 20 hours, and the cross-linking reaction temperature is 30°C;

[0148] Step S5, coating roughening: Grind the coating E to roughen the surface of the coating E, expose the collagen fiber fluff, and take out the coating from the mold to obtain a moisture-absorbing coating;

[0149] Step S6, preparing a mixed solution F: Disperse polyurethane resin, acrylic resin, sorbitol, salicylic acid ester, and phase change microspheres in dimethylformamide to form a mixed solution F; the mass concentration of polyurethane resin in the mixed solution F is 30%; the mass concentration of acrylic resin in solution F is 30%; the mass concentration of sorbitol in solution F is 6%; the mass concentration of salicylic acid ester in solution F is 6%; the mass concentration of phase change microspheres in solution F is 3%; the diameter of the phase change microspheres is 1μm; the phase change microsphere shell is acrylonitrile copolymer, and the inside of the phase change microsphere is isobutane;

[0150] Step S7, Magnetic Force Mapping: Add neodymium iron boron pigment to the mixed liquid F, mix evenly to obtain the mixed liquid G; coat the mixed liquid G in a mold, and then place it in a magnetic field. Under the guidance of the magnetic field, the neodymium iron boron pigment automatically forms a pattern to obtain the magnetized pattern layer H; the mass concentration of the neodymium iron boron pigment in the mixed liquid G is 10%; the magnetic field strength is 2.5 T, and the coating thickness is 100 μm.

[0151] Step S8, Infrared Heating Pre-Curing: Pre-cure the magnetized pattern layer H by infrared heating to obtain the coating I; the infrared wavelength is 3 μm, the pre-curing temperature is 40 °C; the pre-curing time is 24 hours.

[0152] Step S9, Water Bath Washing to Remove Dimethylformamide: Place the coating I in water and wash to remove dimethylformamide to obtain the breathable coating J.

[0153] Step S10, Infrared Heating: Cure the breathable coating J by infrared heating to obtain the coating K; the infrared wavelength is 3 μm, the curing temperature is 60 °C; the curing time is 2 hours; the thickness of the coating K is 20 μm.

[0154] Step S11, Immersion in 3-Aminopropyltriethoxyperfluorohexylsilane: Dissolve 3-aminopropyltriethoxyperfluorohexylsilane in dimethylformamide to obtain the solution L; immerse the coating K in the solution L to obtain the coating M; the mass concentration of 3-aminopropyltriethoxyperfluorohexylsilane in the solution L is 4%; the immersion is divided into a first-stage immersion and a second-stage immersion; the first-stage immersion temperature is 2 °C, and the first-stage immersion time is 4 hours; the second-stage immersion temperature is 70 °C, and the second-stage immersion time is 2 hours.

[0155] Step S12, Preparation of Hydrophobic Coating: Perform a surface modification reaction on the coating M to obtain the coating N; the surface modification reaction temperature is 100 °C; the surface modification reaction time is 2 hours; wash with water to remove dimethylformamide in the coating N, which is the hydrophobic coating.

[0156] Step S13, Preparation of Liquid Skin Coating: Use an adhesive to bond the opposite side of the pattern surface of the hydrophobic coating to the opposite side of the villous surface of the moisture-absorbing coating to obtain the liquid skin coating; the adhesive is acrylate.

[0157] The liquid skin coatings of Examples 1-3 were tested, and the test results are shown in the following table.

[0158] The moisture-absorbing coating has good hydrophilicity. When measured with the moisture-absorbing coating in contact with water, as the glyoxal concentration increases from 4% (Example 1) to 6% (Example 3), a denser network is formed by cross-linking with chitosan-NH2, restricting the swelling of the chain segments and reducing the water absorption performance of the moisture-absorbing coating.

[0159] The liquid skin coating has good air permeability. The air permeability of the liquid skin coating is affected by the moisture-absorbing coating and the hydrophobic coating. As the DMF content decreases, the air permeability becomes lower and lower; as the phase change microspheres increase, the air permeability becomes higher and higher.

[0160] The liquid skin coating has high tear resistance. The air permeability of the liquid skin coating is affected by both the moisture-absorbing coating and the hydrophobic coating.

[0161] The liquid skin hydrophobic coating has high hydrophobicity. As the concentration of 3-aminopropyltriethoxyperfluorohexylsilane increases, the hydrophobic performance of Examples 1 to 3 increases. This measurement is only carried out on one side of the hydrophobic coating.

[0162] Table 7: Test results of examples

[0163]

Claims

1. A method for preparing a liquid skin coating, characterized in that, It includes the following steps: Step S1, preparing mixture A: Dispersing chitosan, collagen fibers, short-chain polylactic acid, maltose, and ethoxydiglycol in water to form mixture A; Step S2, homogenizing to prepare microbubble liquid C: Adding sodium dodecyl sulfate to mixture A to form mixture B, and homogenizing to generate microbubbles in mixture B to form microbubble liquid C; Step S3, preparing microporous coating D: Coating microbubble liquid C in a mold and drying to form microporous coating D; Step S4, glyoxal impregnation: Impregnating microporous coating D in a glyoxal solution for cross-linking reaction to form coating E; Step S5, coating roughening: Grinding coating E to roughen the surface of coating E, exposing the collagen fiber fluff, and taking out the coating from the mold to obtain the moisture-absorbing coating; Step S6, preparing mixture F: Dispersing polyurethane resin, acrylic resin, sorbitol, salicylate, and phase change microspheres in dimethylformamide to form mixture F; Step S7, magnetic mapping: Adding neodymium iron boron pigment to mixture F, mixing evenly to form mixture G; Coating mixture G in a mold, and then placing it in a magnetic field. Under the guidance of the magnetic field, the neodymium iron boron pigment automatically forms a pattern to form the magnetized pattern layer H; Step S8, infrared heating pre-curing: Pre-curing the magnetized pattern layer H by infrared heating to form coating I; Step S9, water bath washing to remove dimethylformamide: Placing coating I in water and washing to remove dimethylformamide to form the breathable coating J; Step S10, infrared heating secondary curing: Curing the breathable coating J by infrared heating to form coating K; Step S11, 3-aminopropyltriethoxyperfluorohexylsilane impregnation: Dissolving 3-aminopropyltriethoxyperfluorohexylsilane in dimethylformamide to form solution L; Impregnating coating K in solution L to form coating M; Step S12, preparing the hydrophobic coating: Performing a surface modification reaction on coating M to form coating N; Washing with water to remove dimethylformamide in coating N, which is the hydrophobic coating; Step S13, preparing the liquid leather coating: Using an adhesive to bond the opposite side of the patterned surface of the hydrophobic coating to the opposite side of the fluff surface of the moisture-absorbing coating to form the liquid leather coating.

2. The preparation method according to claim 1, wherein, In step S1, the molecular weight of chitosan is 100KDa to 200KDa, and the degree of deacetylation is 90% to 100%; the mass concentration of chitosan in solution A is 3% to 5%; the mass concentration of collagen fibers in solution A is 0.1% to 0.3%; the mass concentration of short-chain polylactic acid in solution A is 5% to 7%; the mass concentration of maltose in solution A is 1% to 3%; the mass concentration of ethoxydiglycol in solution A is 0.1% to 0.3%.

3. The preparation method according to claim 2, wherein In step S2, the mass concentration of sodium dodecyl sulfate in solution B is 1% to 4%.

4. The preparation method according to claim 3, characterized in that, In step S3, the thickness of the microporous coating D is 20μm to 40μm; the drying temperature is 50°C to 60°C.

5. The preparation method according to claim 4, characterized in that, In step S4, the mass concentration of the glyoxal solution is 4% to 6%, and the solvent is ethanol; the cross-linking reaction time is 10 hours to 20 hours, and the cross-linking reaction temperature is 20°C to 30°C.

6. The preparation method according to claim 5, characterized in that In the step S6, the mass concentration of the polyurethane resin in the mixture F is 20% to 30%; the mass concentration of the acrylic resin in the solution F is 20% to 30%; the mass concentration of the sorbitol in the solution F is 5% to 6%; the mass concentration of the salicylate in the solution F is 5% to 6%; the mass concentration of the phase change microspheres in the solution F is 2% to 3%; the diameter of the phase change microspheres is 1 μm to 5 μm; the shell of the phase change microspheres is acrylonitrile copolymer, and the inside of the phase change microspheres is isobutane.

7. The preparation method according to claim 6, characterized in that, In the step S7, the mass concentration of the neodymium iron boron pigment in the mixture G is 5% to 10%; the magnetic field strength is 1.5 T to 2.5 T, and the coating thickness is 100 μm to 150 μm.

8. The preparation method according to claim 7, wherein In the step S8, the infrared wavelength is 1 μm to 3 μm, the pre-curing temperature is 30 °C to 40 °C; the pre-curing time is 20 hours to 24 hours.

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