High-wear-resistance self-repairing leather and production process thereof

Abstract

The invention discloses high-wear-resistance self-repairing leather and a production process thereof. The high-wear-resistance self-repairing leather comprises the following raw materials: a non-woven fabric, a soaking material and a coating, the production process comprises the following steps: 1) pretreating the base material; (2) precise gravure transfer coating; (3) stepped drying and curing; 4) an embossing process; and (5) rolling. The preparation method comprises the following steps: firstly, adding 2-mercaptoethanol on cardanol for subsequent polyurethane synthesis, then generating cardanol benzoxazine with a furan side group through a Mannich reaction, constructing a DA bond through a DA reaction to obtain self-repairing polyurethane resin, and using the self-repairing polyurethane resin as a main material of a soaking material and a coating of a leather surface layer for actual production, so that the self-repairing polyurethane resin has a good application prospect. Finally, the self-repairing leather material with high strength, wear resistance and high flame retardance is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthetic leather manufacturing, and particularly relates to a high-wear-resistance self-repairing leather and a production process thereof. BACKGROUND

[0002] As an important basic material, synthetic leather is widely used in shoes and clothes, luggage, furniture, automotive interiors, and even aerospace fields. With the continuous expansion of application scenarios, especially in high-end industrial fields (such as aero-engine cabin parts, gas turbine sealing parts, etc.), more stringent requirements are put forward for material performance: the material not only needs to have excellent wear resistance to resist long-term friction and wear, but also needs to be self-repairing when surface damage (such as fine scratches and cracks) occurs, so as to maintain its functional integrity and prolong its service life, and reduce maintenance costs.

[0003] Traditional self-repairing synthetic leather technology mainly relies on two strategies: using the molecular chain movement ability of soft chain segments (such as long-chain polyols) to realize the recombination of physical entanglement; and introducing microcapsules or blood vessel networks to encapsulate repair agents.

[0004] However, these methods have significant limitations:

[0005] Conflict between mechanical strength and self-repairing property: self-repairing relying on soft chain segments often sacrifices the rigidity and wear resistance of the material.

[0006] High wear resistance usually requires high cross-linking density and rigid structural skeleton, but this will severely limit the movement ability of molecular chains, hindering the repair process of damaged parts. In other words, the existing technical system is difficult to achieve an ideal balance between high wear resistance and high-efficiency self-repairing property.

[0007] Limited and irreversible repair capacity: physical entanglement repair is usually low in efficiency and irreversible. Microcapsule / blood vessel network technology has the problems of single use of repair agent, limited repair capacity, complex process, and possible introduction of additional weak points.

[0008] Thermal stability and processability challenges: Some self-repairing systems based on dynamic covalent bonds (such as Diels-Alder reaction) have a mismatch between the reversible reaction temperature window and the high-temperature curing conditions required for synthetic leather processing. High-temperature curing process easily leads to irreversible inactivation of dynamic bonds or decomposition of repair components, thereby losing self-repairing function. At the same time, high-solid-content resin coatings used to meet wear resistance requirements are prone to produce defects such as pinholes and sagging during coating, which puts extremely high requirements on coating process control.

[0009] Therefore, developing a new synthetic leather material with ultra-high wear resistance, high-efficiency heat-reversible self-repairing ability, excellent processing adaptability (avoiding coating defects and thermal decomposition inactivation), and environmental friendliness, and a production process thereof, has become a key problem to be broken through in the synthetic leather manufacturing technical field. SUMMARY

[0010] The present application aims to solve the problems existing in the prior art and proposes a high-wear-resistance self-repairing leather and a production process thereof.

[0011] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0012] The present application first proposes a production process of high-wear-resistance self-repairing leather, comprising the following steps:

[0013] S1, substrate pretreatment

[0014] After the non-woven fabric passes through a 10kW plasma treatment machine in an air atmosphere, ±15kV bipolar ion wind is used to remove surface particles to avoid pinholes during coating;

[0015] A three-roll mill with a roll gap of 0.5mm and a pressure of 0.3MPa is used to soak the non-woven fabric in the impregnated material; the impregnated material is composed of 100 parts of self-repairing polyurethane resin, 540-560 parts of dimethylformamide and 0.2 parts of leveling agent by mass fraction;

[0016] After the non-woven fabric is soaked, it is uniformly heated by hot air at 50℃ for 90s to eliminate the hygroscopicity of the substrate and improve the leveling property of the coating;

[0017] S2, precision gravure transfer coating

[0018] The coating system adopts a combination process of closed feeding and micro-gravure roller:

[0019] A constant temperature feeding pump is used to transport the coating at a pressure of 0.2MPa, and the flow rate is stabilized at 60mL / min;

[0020] The coating is composed of self-repairing polyurethane resin, triphenylphosphine, wetting dispersant, nano-SiO2, defoaming agent, UV absorber, stabilizer and antioxidant with a mass ratio of 265-281:0.3:1.5:12:0.4:1.5:1.5:0.8, and the solid content is adjusted to 30% by dimethylformamide;

[0021] A 60° inclined angle cavity doctor blade is used to apply a line pressure of 1.5kg / cm to accurately remove excess coating on the roller surface;

[0022] Gravure transfer is carried out, and a mesh volume of 23cm 3 / m 2The micro gravure roller, the roller speed and the substrate speed ratio 1:1.2, the realization 70-75% coating transfer rate, back pressure roller to ensure uniform transfer with 50N / cm linear pressure, after coating to get the coated substrate;

[0023] S3, ladder drying and curing

[0024] The coated substrate into the multi-section oven through three drying section for curing, after curing, get the dense surface synthetic leather;

[0025] S4, embossing process

[0026] The use of double roller embossing machine for embossing dense surface synthetic leather, embossing immediately after the diameter of 800mm 5℃ circulating water cooling roller setting, get embossed synthetic leather;

[0027] S5, winding

[0028] The embossed synthetic leather roll 0.5g / m 2 The polydimethylsiloxane after winding package, get a kind of high wear resistance self repairing leather.

[0029] Preferably, in the S1, the non-woven fabric is polyester / cotton blended non-woven fabric, 300-500g / m 2 , thickness in 1.2-1.8mm; leveling agent is BYK-381;

[0030] The preparation process of the self repairing polyurethane resin, including the following steps:

[0031] The 4,4'-bismaleimide diphenylmethane is added to the cardanol based benzoxazine modified polyurethane, nitrogen protection, 60℃, dark stirring 2h, -0.08MPa vacuum degassing 20min, get cardanol based benzoxazine modified self repairing polyurethane, namely self repairing polyurethane resin, cardanol based benzoxazine modified polyurethane (containing furan group) and 4,4'-bismaleimide diphenylmethane Diels-Alder cycloaddition:

[0032] DA bond can be reversed at 60-100℃ break / recombination, realize the damage repair.

[0033] Preferably, the furan group of the self repairing polyurethane resin and the maleimide of 4,4'-bismaleimide diphenylmethane molar ratio is 1:1.1;

[0034] The viscosity of cardanol based benzoxazine modified self repairing polyurethane at 25℃ is 2400±300cP;

[0035] The preparation process of cardanol based benzoxazine modified polyurethane, including the following steps:

[0036] The cardanol-based benzoxazine is heated to 60°C, then polyetheramine D230, dibutyltin dilaurate, hexamethylene diisocyanate are added, stirred at 500 rpm for 1 h, and homogenized at 60 MPa for 3 times. The viscosity is adjusted to 2500±300 cP at 25°C with dimethylformamide to obtain the cardanol-based benzoxazine modified polyurethane.

[0037] The isocyanate groups of hexamethylene diisocyanate react with the hydroxyl groups of the cardanol-based benzoxazine:

[0038] The introduced furan groups provide dynamic covalent bond sites for self-repair.

[0039] Preferably, the amount of dibutyltin dilaurate is 1% of the total mass of the cardanol-based benzoxazine modified polyurethane reactants;

[0040] The mass ratio of cardanol-based benzoxazine, hexamethylene diisocyanate, and polyetheramine D230 is 100:58-64:15-25.

[0041] Preferably, the preparation process of the cardanol-based benzoxazine includes the following steps:

[0042] Cardanol is dissolved in 2-mercaptoethanol and heated to 80°C. The solution is stirred at 200 rpm until dissolution. Photoinitiator 184 is added, and the mixture is subjected to ultraviolet light at 375 nm for 24 h. After the reaction is complete, the product is dissolved in ethyl acetate, washed with saturated brine and distilled water three times each, then dried with anhydrous sodium sulfate, and finally rotary evaporated to remove ethyl acetate to obtain the cardanol-based polyol.

[0043] Cardanol (containing unsaturated long chains) undergoes a radical addition reaction with 2-mercaptoethanol under the initiation of ultraviolet light:

[0044] The introduction of hydroxyl groups (-OH) provides reaction sites for subsequent polyurethane synthesis.

[0045] Polyformaldehyde aqueous solution is slowly added to the cardanol-based polyol, and furfurylamine is added after the dropwise addition is complete. The temperature is raised to 80-85°C, and the reaction mixture is refluxed for 4-5 h. The reaction mixture is distilled under reduced pressure to remove water, and dimethylformamide is added to adjust the solid content to 70% to obtain the cardanol-based benzoxazine.

[0046] Cardanol-based polyol, polyformaldehyde, and furfurylamine are condensed:

[0047] The benzoxazine monomer containing furan groups has both ring-opening polymerization activity and D-A reaction sites.

[0048] Preferably, the molar ratio of the cardanol to 2-mercaptoethanol is 1:2.2; the molar ratio of the cardanol-based polyol, formaldehyde and furfuryl amine is 1:2.2:1; the mass fraction of the added aqueous solution of paraformaldehyde is 37%; and the amount of the photoinitiator 184 is 1.5% of the total mass of the cardanol-based polyol reactants.

[0049] Preferably, in S2, the wet film thickness of the coating on the non-woven fabric is 100±5 μm, and the corresponding dry film thickness is 30±2 μm.

[0050] The wetting dispersant is BYK-110, the defoaming agent is BYK-066N, the UV absorber is UV absorber UV-329, the stabilizer is hindered amine light stabilizer, and the antioxidant is antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0051] Preferably, in S3, the program of the three-stage drying section is as follows:

[0052] Solvent evaporation section: horizontal flow air speed 5 m / s, removal of 60% volatile solvent, 60℃, for 30 s;

[0053] Gelation section: air floating type 8 m / s air speed triggers resin viscosity sudden increase, preliminary shaping of the coating, 80℃, for 45 s;

[0054] Leveling section: infrared radiation heating eliminates orange peel, surface roughness Ra≤0.2 μm, 100℃, for 15 s;

[0055] The program of the multi-stage oven is as follows:

[0056] Zone 1 is 80℃, for 30 min;

[0057] Zone 2 is from 120℃, with a heating rate of 2℃ / min, to 140℃, after the heating is completed, for 120 min;

[0058] Zone 3 is 60℃, for 24 h;

[0059] Zone 4 is 100℃, for 30 min.

[0060] The application also provides a high-wear-resistance self-repairing leather prepared by the production process of any one of claims 1-8.

[0061] Compared with the prior art, the application has the following beneficial effects:

[0062] The application obtains a cardanol-based benzoxazine modified self-repairing polyurethane through molecular level design, uses cardanol benzoxazine as a structure main body to provide rigid support, and a phenolic ring and a benzoxazine six-membered ring form a high-strength skeleton, and a side chain furan group thereof acts as a "reversible switch" to form a thermal reversible covalent bond through Diels-Alder cycloaddition reaction with 4,4'-bismaleimide diphenylmethane; and long alkyl chains derived from cardanol are arranged in a direction on a coating surface to form a hydrophobic barrier, reduce surface energy and block water molecule penetration.

[0063] The application constructs a dynamic covalent network, for a traditional synthetic leather material, self-repairing performance usually depends on soft chain segments to realize molecular movement, but mechanical strength is sacrificed; and a high wear-resistant coating usually needs high crosslinking density, which limits repairability. The application forms a stable crosslinking network through DA reversible reaction of furan groups of cardanol benzoxazine and bismaleimide at room temperature, and realizes micro-crack repair through reversible dissociation under heat (above 60 DEG C) while having super strong wear resistance.

[0064] A traditional self-repairing synthetic leather is prone to pinholes and sagging due to high solid content resin coating, and self-repairing components are prone to decomposition during high temperature curing. The application solves the problems of coating defects, thermal decomposition inactivation, and wear resistance-self-repairing exclusion through low viscosity high solid content system, low temperature step curing, and nano-SiO2 high pressure homogenization dispersion enhanced resin coating and DA self-repairing dynamic network cooperation, and provides a new solution for high-end functional synthetic leather.

[0065] In summary, the application successfully develops a high wear-resistant self-repairing leather by designing a molecular structure of self-repairing polyurethane coating. BRIEF DESCRIPTION OF DRAWINGS

[0066] Figure 1 A nuclear magnetic resonance spectrum of a cardanol-based benzoxazine modified polyurethane produced by the application. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application.

[0068] The purity of each drug used in the experiment and its manufacturer are shown in Table 1. Table 1. Raw drug information

[0069] Preparation Example 1:

[0070] The preparation process of the cardanol-based benzoxazine modified self-repairing polyurethane coating includes the following steps:

[0071] The cardanol is dissolved in 2-mercaptoethanol, heated to 80℃, dissolved with stirring at 200rpm, the photoinitiator 184 is added, and it is placed under UV light at 375nm for 24h. After the reaction is complete, the product is dissolved in ethyl acetate, washed with saturated brine and distilled water three times each, then dried with anhydrous sodium sulfate, and finally rotary evaporated to remove the ethyl acetate to obtain the cardanol-based polyol;

[0072] The cardanol-based polyol is slowly added dropwise with an aqueous solution of paraformaldehyde, and after the dropwise addition is complete, furfurylamine is added. The temperature is raised to 80-85℃, and refluxed for 4-5h to obtain a reaction mixture. The reaction mixture is distilled under reduced pressure to remove water, and NMP is added to adjust the solid content to 70% to obtain the cardanol-based benzoxazine.

[0073] The cardanol-based benzoxazine is heated to 60℃, and then polyetheramine D230, dibutyltin dilaurate, and hexamethylene diisocyanate are added. The mixture is stirred mechanically at 500rpm for 1h, and then homogenized at 60MPa for 3 times. The viscosity is adjusted to 2500±300cP at 25℃ with dimethylformamide to obtain the cardanol-based benzoxazine modified polyurethane.

[0074] The 4,4'-bismaleimide diphenylmethane is added to the cardanol-based benzoxazine modified polyurethane, and the mixture is stirred at 60℃ under nitrogen protection for 2h in the dark, and then vacuum degassed at -0.08MPa for 20min to obtain the cardanol-based benzoxazine modified self-healing polyurethane, i.e. the self-healing polyurethane resin.

[0075] The molar ratio of the furan groups of the self-healing polyurethane resin to the maleimide groups of the 4,4'-bismaleimide diphenylmethane is 1:1.1.

[0076] The viscosity of the cardanol-based benzoxazine modified self-healing polyurethane at 25℃ is 2350cP.

[0077] The amount of dibutyltin dilaurate is 1% of the total mass of the cardanol-based benzoxazine modified polyurethane reactants.

[0078] The mass ratio of the cardanol-based benzoxazine, hexamethylene diisocyanate, and polyetheramine D230 is 100:58-64:15-25.

[0079] The molar ratio of cardanol to 2-mercaptoethanol is 1:2.2. The molar ratio of the cardanol-based polyol, formaldehyde, and furfurylamine is 1:2.2:1. The mass fraction of the added aqueous paraformaldehyde solution is 37%. The amount of photoinitiator 184 is 1.5% of the total mass of the cardanol-based polyol reactants.

[0080] The cardanol-based benzoxazine modified polyurethane was synthesized according to the method of Example 1 using cardanol, 2-mercaptoethanol, aqueous solution of paraformaldehyde, furfuryl amine, hexamethylene diisocyanate, photoinitiator 184 and dibutyl tin dilaurate, and after isolation and purification, the proton nuclear magnetic resonance spectrum was detected to obtain Figure 1 ;

[0081] In the figure, the single peak at the right end is attributed to the methyl group at the tail of cardanol, the peaks at 1.2-2.7 ppm are attributed to the methylene groups on the cardanol and hexamethylene diisocyanate; the peak at 5.3 ppm is attributed to the N-H bond on the urea bond; the peak at 5.6 ppm is attributed to the C-H bond on the benzoxazine connected with O and N; and the six peaks at the left end are attributed to the C-H bonds on the furan ring and benzene ring.

[0082] Preparation Example 2:

[0083] The raw material formula and test method were the same as those of Preparation Example 1, but the mass ratio of the cardanol-based benzoxazine, hexamethylene diisocyanate and polyetheramine D230 was 100:62:20, and the viscosity of the self-repairing polyurethane coating was 2500 cP.

[0084] Preparation Example 3:

[0085] The raw material formula and test method were the same as those of Preparation Example 1, but the mass ratio of the cardanol-based benzoxazine, hexamethylene diisocyanate and polyetheramine D230 was 100:64:25, and the viscosity of the self-repairing polyurethane coating was 2600 cP.

[0086] Example 1:

[0087] S1, substrate pretreatment

[0088] After the non-woven fabric was treated by a 10 kW plasma treatment machine in an air atmosphere, the surface particles were removed by ±15 kV bipolar ion wind to avoid pinholes during coating;

[0089] The non-woven fabric was immersed in the dipping material using a three-roll mill with a roll gap of 0.5 mm and a pressure of 0.3 MPa; the dipping material was composed of 100 parts of self-repairing polyurethane resin, 540-560 parts of dimethylformamide and 0.2 parts of leveling agent by mass fraction;

[0090] After the non-woven fabric was immersed, it was uniformly heated using hot air at 50°C for 90 s to eliminate the hygroscopicity of the substrate and improve the leveling property of the coating;

[0091] S2, precision gravure transfer coating

[0092] The coating system used a combination process of closed feeding and microgravure roll:

[0093] The coating was transported by using a constant temperature feed pump at 60℃ with a pressure of 0.2MPa, and the flow rate was stabilized at 60mL / min;

[0094] The coating was composed of self-repairing polyurethane resin, triphenylphosphine, wetting dispersant, nano-SiO2, defoaming agent, UV absorber, stabilizer and antioxidant with a mass ratio of 263:0.3:1.5:12:0.4:1.5:1.5:0.8, and the solid content was adjusted to 30% by dimethylformamide;

[0095] The excess coating on the roller surface was accurately scraped off by using a 60° inclined angle cavity doctor blade with a line pressure of 1.5kg / cm;

[0096] The gravure transfer was performed, and a microgravure roller with a mesh volume of 23cm 3 / m 2 was used, the roller speed to substrate speed ratio was 1:1.2, the coating transfer rate was 70-75%, the back pressure roller was used to ensure uniform transfer with a line pressure of 50N / cm, and the coated substrate was obtained after coating;

[0097] S3, stepwise drying and curing

[0098] The coated substrate was dried by three-stage drying section and then cured in a multi-section oven, and a dense surface synthetic leather was obtained after curing;

[0099] S4, embossing process

[0100] The dense surface synthetic leather was embossed by using a double roller embossing machine, and was immediately shaped by a 5℃ circulating water cooling roller with a diameter of 800mm, and an embossed synthetic leather was obtained;

[0101] S5, winding

[0102] The embossed synthetic leather was roll coated with 0.5g / m 2 of polydimethylsiloxane, and was wound and packaged to obtain a high wear-resistant self-repairing leather.

[0103] In S1, the non-woven fabric was a polyester / cotton blended non-woven fabric with a weight of 300-500g / m 2 and a thickness of 1.2-1.8mm; the leveling agent was BYK-381;

[0104] In S2, the wet film thickness of coating was 100±5μm, and the corresponding dry film thickness was 30±2μm.

[0105] In S3, the three-stage drying section program was set as follows:

[0106] Solvent evaporation section: cross-flow air speed 5m / s, remove 60% volatile solvent, 60℃, 30s;

[0107] Gelation section: air floating 8 m / s wind speed triggers resin viscosity sudden increase, preliminary sizing coating, 80℃, 45s;

[0108] Leveling section: infrared radiation heating eliminates orange peel, surface roughness Ra≤0.2μm, 100℃, 15s;

[0109] The program settings of the multi-section oven are as follows:

[0110] Zone 1 is 80℃, 30min;

[0111] Zone 2 is from 120℃, with a heating rate of 2℃ / min, to 140℃, after the temperature rise is completed, 120min;

[0112] Zone 3 is 60℃, 24h;

[0113] Zone 4 is 100℃, 30min.

[0114] Example 2:

[0115] Using 100kg of the self-repairing polyurethane coating of Preparation Example 2, a high wear-resistant self-repairing leather is prepared according to the preparation method of Example 1. After the coating is composed of self-repairing polyurethane resin, triphenylphosphine, wetting dispersant, nano-SiO2, defoaming agent, UV absorber, stabilizer and antioxidant with a mass ratio of 274:0.3:1.5:12:0.4:1.5:1.5:0.8, the solid content is adjusted to 30% by dimethylformamide.

[0116] Example 3:

[0117] Using 100kg of the self-repairing polyurethane coating of Preparation Example 3, a high wear-resistant self-repairing leather is prepared according to the preparation method of Example 1. After the coating is composed of self-repairing polyurethane resin, triphenylphosphine, wetting dispersant, nano-SiO2, defoaming agent, UV absorber, stabilizer and antioxidant with a mass ratio of 289:0.3:1.5:12:0.4:1.5:1.5:0.8, the solid content is adjusted to 30% by dimethylformamide.

[0118] Also designed:

[0119] Comparative Example 1: The same as the preparation method of Preparation Example 2, but the mass ratio of cardanol-based benzoxazine, hexamethylene diisocyanate and polyetheramine D230 is 100:10:20;

[0120] Comparative Example 2: The same as the preparation method of Preparation Example 2, but the mass ratio of cardanol-based benzoxazine, hexamethylene diisocyanate and polyetheramine D230 is 100:100:20;

[0121] Comparative Example 3: The same as the formulation and experimental method of Preparation Example 2, but the mass ratio of cardanol-based benzoxazine, hexamethylene diisocyanate, and polyetheramine D230 is 100:62:5;

[0122] Comparative Example 4: The same as the formulation and experimental method of Preparation Example 2, but the mass ratio of cardanol-based benzoxazine, hexamethylene diisocyanate, and polyetheramine D230 is 100:62:50;

[0123] According to the standards and testing methods of ISO 3376:2020 "Leather-Determination of tensile strength and elongation", ISO 17074:2019 "Leather-Determination of abrasion resistance", ISO 2419:2012 "Leather-Determination of physical tests-Determination of resistance to hydrolysis", GB / T 14522-2008 "Artificial climate aging test method for plastics, coatings, and rubber materials for mechanical industry products", GB / T 5455-2014 "Textiles-ignition propagation through testing-Vertical flame resistance", EU 2017 / 1000 PFOA related annex, GB 33372-2020 "Limit of volatile organic compounds in adhesives", the present application was tested for mechanical properties, abrasion resistance, ultraviolet aging resistance, flame resistance, VOC emission, PFAS residue, and hydrolysis resistance, and the corresponding results and data were summarized and plotted in Table 2: Table 2. Performance testing data of high abrasion resistance self-repairing leather

[0124] Data analysis:

[0125] From Comparative Examples 2, 1, and 2, it can be seen that the amount of hexamethylene diisocyanate as a crosslinking agent directly determines the content of hard segments in the polyurethane network. If insufficient, the unreacted hydroxyl and amine groups will result in sparse connection points between molecular chains, and the mechanical strength and abrasion resistance of the synthetic leather will collapse. If excessive, the unreacted free -NCO groups will cause two problems, i.e., -NCO reacts with water to generate brittle polyurea, reducing the toughness of the product, and -NCO as a residual monomer volatilizes, causing VOC emission to soar, far exceeding the environmental protection limit.

[0126] From Comparative Examples 2, 3, and 4, it can be seen that polyetheramine D230 as a flexible chain segment extender in the product can provide molecular chain movement ability through its ether bond (-O-). If insufficient, the hard segment (benzoxazine / HDI) of the polyurethane will have a high proportion, and the segment activity will be limited, which will cause the brittleness of the artificial leather to increase. If excessive, the coating will be dominated by the soft segment phase, the expected strength skeleton will be destroyed, the system will be excessively extended, and the carrying capacity will be lost.

[0127] Although the repair efficiency is not directly tested, the amount of D230 affects the dynamic bond behavior through the activity of the chain segment, that is, when it is insufficient, the steric hindrance is large, the molecular chain is frozen, the furan / maleimide is difficult to access and recombine, and the repair efficiency of the system is low; when it is excessive, the chain segment is too active, and the dynamic bond cannot be accurately positioned for recombination after dissociation, and the repair precision is reduced.

[0128] The above merely describes the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacements or changes according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A production process for highly wear-resistant self-repairing leather, characterized in that: The following steps are involved: S1. Substrate pretreatment After the non-woven fabric passes through a 10kW, air atmosphere plasma treatment machine, ±15kV bipolar ion wind is used to remove surface particles to avoid pinholes in the coating; The nonwoven fabric is impregnated with a three-roll mill having a roller gap of 0.5 mm and a pressure of 0.3 MPa; the impregnation material is composed of 100 parts by mass of a self-repairing polyurethane resin, 540-560 parts by mass of dimethylformamide, and 0.2 parts by mass of a leveling agent; After the non-woven fabric is soaked, use 50℃ hot air to evenly heat it for 90s to eliminate the substrate's moisture absorption and improve the coating's leveling properties; S2, precision gravure transfer coating The coating system adopts a combination of closed feeding and micro gravure roller technology: Use a 60℃ constant temperature feed pump to deliver the paint at a pressure of 0.2MPa and stabilize the flow rate at 60mL / min; The coating comprises a self-repairing polyurethane resin, triphenylphosphine, a wetting and dispersing agent, nano-SiO2, a defoaming agent, a UV absorber, a stabilizer and an antioxidant in a mass ratio of 265-281:0.3:1.5:12:0.4:1.5:1.5:0.8, and the solid content is adjusted to 30% by dimethylformamide; Use a 60° angled chamber scraper to apply a linear pressure of 1.5kg / cm to accurately scrape off excess paint from the roller surface; For gravure transfer printing, the cell volume is 23cm 3 / m 2 The micro-gravure roller has a roller speed to substrate speed ratio of 1:1.2, achieving a coating transfer rate of 70-75%. The back pressure roller ensures uniform transfer with a line pressure of 50N / cm. After coating, a coated substrate is obtained; S3, step-by-step drying and curing The coated substrate passes through a three-stage drying section and enters a multi-stage oven for curing. After curing, a dense surface layer of synthetic leather is obtained; S4, embossing process The dense surface layer synthetic leather was embossed using a double-roller relief embossing machine, and immediately after embossing, it was shaped by a 5°C circulating water cooling roller with a diameter of 800 mm to obtain an embossed synthetic leather; S5, Rolling Roller coating 0.5g / m2 for embossed synthetic leather 2 After the polydimethylsiloxane is added, it is rolled and packaged to obtain a highly wear-resistant self-repairing leather.

2. The production process of a highly wear-resistant self-repairing leather according to claim 1, characterized in that: In S1, the non-woven fabric is a polyester / cotton blended non-woven fabric, 300-500g / m 2 , thickness is 1.2-1.8mm; leveling agent is BYK-381; The preparation process of the self-repairing polyurethane resin comprises the following steps: 4,4'-bismaleimide diphenylmethane was added to cardanol-benzoxazine-modified polyurethane, stirred at 60°C in the dark for 2 hours under nitrogen protection, and vacuum degassed at -0.08 MPa for 20 minutes to obtain cardanol-benzoxazine-modified self-healing polyurethane, i.e., self-healing polyurethane resin.

3. The production process of a highly wear-resistant self-repairing leather according to claim 2, characterized in that: The molar ratio of the furan group of the self-repairing polyurethane resin to the maleimide of 4,4'-bismaleimidodiphenylmethane is 1:1.1; The viscosity of the cardanol-based benzoxazine-modified self-healing polyurethane at 25°C is 2400±300 cP; The preparation process of cardanol-based benzoxazine-modified polyurethane comprises the following steps: After heating the cardanol-benzoxazine to 60°C, polyetheramine D230, dibutyltin dilaurate, and hexamethylene diisocyanate were added, and the mixture was mechanically stirred at 500 rpm for 1 hour and homogenized at 60 MPa for three times. The viscosity was adjusted to 2500±300 cP with dimethylformamide at 25°C to obtain a cardanol-benzoxazine-modified polyurethane.

4. The production process of a highly wear-resistant self-repairing leather according to claim 3, characterized in that: The amount of dibutyltin dilaurate is 1% of the total mass of the cardanol-based benzoxazine-modified polyurethane reactants; The mass ratio of cardanol benzoxazine, hexamethylene diisocyanate and polyetheramine D230 is 100:58-64:15-25.

5. The production process of a highly wear-resistant self-repairing leather according to claim 3, characterized in that: The preparation process of the cardanol-based benzoxazine comprises the following steps: Dissolve cardanol in 2-mercaptoethanol, heat to 80°C, stir at 200 rpm to dissolve, add photoinitiator 184, and place under 375 nm ultraviolet light to react for 24 hours. After the reaction is completed, dissolve the product in ethyl acetate, wash with saturated salt water and distilled water three times, then dry with anhydrous sodium sulfate, and finally remove ethyl acetate by rotary evaporation to obtain cardanol-based polyol; Slowly add paraformaldehyde aqueous solution to the cardanol-based polyol, and then add furfural amine; heat to 80-85° C., reflux for 4-5 hours to obtain a reaction mixture; remove water from the reaction mixture by vacuum distillation, and add dimethylformamide to adjust the solid content to 70% to obtain cardanol-based benzoxazine.

6. The production process of a highly wear-resistant self-repairing leather according to claim 5, characterized in that: The molar ratio of cardanol to 2-mercaptoethanol is 1:2.2; the molar ratio of cardanol-based polyol, formaldehyde and furfurylamine is 1:2.2:1; the mass fraction of the added paraformaldehyde aqueous solution is 37%; and the amount of photoinitiator 184 used is 1.5% of the total mass of the cardanol-based polyol reactants.

7. The production process of a highly wear-resistant self-repairing leather according to claim 1, characterized in that: In S2, the wet film thickness coated on the non-woven fabric is 100±5 μm, and the corresponding dry film thickness is 30±2 μm; The wetting and dispersing agent is BYK-110, the defoaming agent is BYK-066N, the UV absorber is ultraviolet absorber UV-329, the stabilizer is hindered amine light stabilizer, and the antioxidants are antioxidant 1010 and antioxidant 168 with a mass ratio of 1:

1.

8. The production process of a highly wear-resistant self-repairing leather according to claim 1, characterized in that: The three-stage drying section program in S3 is set as follows: Solvent volatilization stage: cross-flow wind speed 5m / s, remove 60% of volatile solvent, 60℃, last 30s; Gelation stage: air flotation at 8m / s wind speed triggers a sudden increase in resin viscosity, initially setting the coating, at 80°C for 45s; Leveling stage: Infrared radiation heating eliminates orange peel, surface roughness Ra≤0.2μm, at 100℃, for 15s; The program settings of the multi-stage oven are: Temperature zone 1 is 80°C for 30 min; Temperature zone 2 was heated from 120°C to 140°C at a rate of 2°C / min and continued for 120 min after the heating was completed; Temperature zone 3 is 60°C for 24 hours; Temperature zone 4 is 100°C for 30 minutes.

9. A highly wear-resistant self-repairing leather, prepared by the production process of the highly wear-resistant self-repairing leather according to any one of claims 1 to 8.

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