Water-based velvet-feeling surface layer composition for synthetic leather and preparation method of water-based velvet-feeling surface layer composition

Abstract

The invention discloses a water-based velvet-feeling surface layer composition for synthetic leather and a preparation method. The water-based velvet-feeling surface layer composition is prepared from the following components in parts by weight: 91-98 parts of aliphatic waterborne polyurethane dispersion; 5 to 25 parts of polystyrene microspheres; 5-25 parts of silicone rubber powder; 1-5 parts of a cross-linking agent; 0.05 to 1 part of a defoaming agent; 0.5-2 parts of a wetting agent; 0.5-2 parts of a hand feeling agent; and 0.5-2 parts of a stabilizer. The polystyrene microspheres and the silicone rubber powder are combined and used in the aliphatic waterborne polyurethane dispersion, so that the unqualified phenomena of poor leveling property, shrinkage cavities, bright spots and the like during the preparation of the velvet leather are solved. A leather product prepared from the velvet surface layer has the advantages of skin-fitting velvet feeling and the like, and can meet the physical property requirements of sofa leather.

Description

Technical Field

[0001] The invention relates to the field of waterborne polyurethane resins, and in particular to a waterborne polyurethane velvety surface layer composition for synthetic leather and a preparation method thereof. Background Art

[0002] Synthetic leather is man-made leather, which is a product that imitates genuine leather in structure, feel and style. At present, its raw materials are still mainly solvent-based polyurethane resins, and the solvents used are mainly dimethylformamide (DMF), butanone (MEK), toluene, etc. Although there are solvent recovery devices, the separation effect is not ideal, which not only causes material waste, but also causes environmental pollution. At present, consumers have high demand for products that promote environmental protection principles, services, manufacturing and green measures, and are eager to pursue environmentally friendly products with longer life and lower environmental impact of processes.

[0003] The materials used for sofa decoration have more contact with the human body. Among them, suede leather has a skin-feeling and non-cool tactile effect, making it the mainstream type of sofa decoration leather.

[0004] Patent No. 201410295312.X discloses a velvet-feeling treatment agent and a preparation method thereof, which achieves the velvet-feeling effect through matting powder, glass microbeads and silicone oil. The effect is not wear-resistant and not long-lasting, and can only be achieved through post-processing.

[0005] Patent No. 201911049315.4 discloses a water-based foamed velvety solvent-free composite polyurethane synthetic leather for sofas and its preparation method. The velvety effect is achieved by foaming yangbuck leather resin and yangbuck powder at high temperature. It has a rough grinding feel and cannot maintain the velvety effect after wear-resistant treatment.

[0006] Therefore, it is necessary to develop a water-based, environmentally friendly suede material for synthetic leather to solve the unqualified phenomena such as poor leveling, shrinkage holes, bright spots, and poor wear resistance of the current suede leather materials. Summary of the invention

[0007] In view of the above problems existing in the prior art, the present invention provides a water-based suede surface layer composition for synthetic leather and a preparation method thereof. The present invention uses polystyrene microspheres and silicone rubber powder in combination in an aliphatic water-based polyurethane dispersion to solve the unqualified phenomena such as poor leveling, shrinkage cavities, bright spots, and poor wear resistance of suede leather materials. The leather material prepared from the suede surface layer has the advantages of good skin feel and good skin-fitting feel, and can meet the physical property requirements of sofa leather and the like.

[0008] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0009] In one aspect, the present invention provides an aqueous suede surface layer composition for synthetic leather, which is prepared from the following components in parts by weight:

[0010]

[0011]

[0012] Preferably, the aqueous suede surface layer composition for synthetic leather is prepared from the following components in parts by weight:

[0013]

[0014] In a specific example of the present invention, the aliphatic aqueous polyurethane dispersion has an acid value of 20-50 mgKOH / g, such as 20, 30, 40, 50 mgKOH / g, a particle size of 100-400 nm, such as 100, 200, 300, 400 nm, and a solid content of 35-45 wt%, such as 35, 40, 45 wt%.

[0015] The aliphatic waterborne polyurethane dispersion meeting the above requirements of the present invention has been reported in the prior art and can be directly purchased or prepared by any feasible method. The present invention has no special requirements for its source. For example, as a preferred embodiment, the aliphatic waterborne polyurethane dispersion can be a commercially available product of Wanhua Chemical 3375, 3257, etc.

[0016] The aliphatic waterborne polyurethane dispersion described in the present invention can also be prepared by existing methods, and can generally be prepared by the reaction of polyols and aliphatic isocyanates. For example, patent CN109232851A provides a detailed description of a method for preparing an aliphatic waterborne polyurethane dispersion. Based on these existing studies, the present invention has found a preferred scheme for preparing the above-mentioned aliphatic waterborne polyurethane dispersion. This method is only used to illustrate one of the methods used by the present invention to prepare the aliphatic waterborne polyurethane dispersion, but the source of raw materials for the aliphatic waterborne polyurethane dispersion described in the present invention should not be limited by the steps, raw materials, parameters, etc. in the method. In a preferred example of the present invention, the aliphatic waterborne polyurethane dispersion is prepared by the following steps:

[0017] 1) adding reactive polyol, aliphatic isocyanate, hydrophilic group-containing compound, small molecule diol, catalyst, and the first part of organic solvent into a nitrogen-protected reactor, and heating to react;

[0018] 2) adding a second portion of organic solvent to dilute and cool, adding a post-chain extender and a capping agent to carry out a chain extension reaction, then adding a neutralizing agent to carry out a neutralization reaction, then adding water to carry out shear dispersion, and finally raising the temperature to remove the organic solvent to obtain an aliphatic waterborne polyurethane dispersion.

[0019] In a specific example, the composition of each raw material by mass includes: 100-200 parts of reactive polyol, such as 100, 120, 140, 160, 180, 200 parts, 30-60 parts of aliphatic isocyanate, such as 30, 40, 50, 60 parts, 100-300 parts of organic solvent, such as 100, 150, 200, 250, 300 parts, 20-50 parts of hydrophilic group-containing compound, such as 20, 30, 40, 50 parts, 1-5.5 parts of small molecule diol, such as 1.0, 2.0, 3.0, 4.0, 5.0 parts, 10-30 parts of post-chain extender, for example 10, 15, 20, 25, 30 parts, 10-30 parts of end-capping agent, for example 10, 15, 20, 25, 30 parts, 10-30 parts of neutralizing agent, for example 10, 15, 20, 25, 30 parts; preferably, 120-180 parts of reactive polyol, 40-60 parts of aliphatic isocyanate, 150-250 parts of organic solvent, 25-40 parts of hydrophilic group-containing compound, 1.5-3.5 parts of small molecule diol, 14-22 parts of post-chain extender, 15-25 parts of end-capping agent, 15-25 parts of neutralizing agent;

[0020] Preferably, the amount of the catalyst used, based on the total mass of the reactants, accounts for 0.05-0.5wt%, such as 0.05, 0.1, 0.2, 0.3, 0.4, 0.5wt%, wherein the reactants include reactive polyols, aliphatic isocyanates, hydrophilic group-containing compounds, and small molecule diols.

[0021] In a specific example, based on the total mass of the reactants, the amount of the first part of the organic solvent added is 5-30wt%, such as 5, 10, 20, 30wt%, and the amount of the second part of the organic solvent added is 60-90wt%, such as 60, 70, 80, 90wt%, wherein the reactants include reactive polyols, aliphatic isocyanates, hydrophilic group-containing compounds, and small molecule diols.

[0022] In a specific example, the organic solvent is selected from ketone solvents, preferably one or more of acetone and butanone.

[0023] In a specific example, the aliphatic isocyanate is selected from one or more of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), butylene diisocyanate (BDI), 2,2,4-trimethylhexamethylene diisocyanate, diisocyanatomethylcyclohexane, and diisocyanatomethyltricyclodecane, preferably one or more of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and dicyclohexylmethane diisocyanate (HMDI), and more preferably isophorone diisocyanate (IPDI). The use of aliphatic isocyanate can effectively control side reactions, and the film is transparent and resistant to yellowing. It is used for the surface layer of black and colored suede leather to show the color effect of black fog.

[0024] In a specific example, the reactive polyol has a number average molecular weight of 600-4000, preferably a polycarbonate polyol with a number average molecular weight of 1000-2000; preferably, the polycarbonate polyol is selected from polyhexamethylene carbonate diol, polycarbonate-1,6-hexanediol ester diol, polycaprolactone carbonate hexamethylene ester diol, polycarbonate-1,4-butanediol-1,6-hexanediol ester diol, polypropylene carbonate diol, polyethylene carbonate diol, polycarbonate-1,5 -pentanediol-1,6-hexanediol ester diol, polybutylene carbonate diol, polycyclohexanedimethanol carbonate-1,6-hexanediol ester diol, one or more, more preferably polycarbonate-1,6-hexanediol ester diol (such as Asahi Chemical 980r), polycarbonate-1,4-butanediol-1,6-hexanediol ester diol (such as Asahi Chemical GE502) and polycarbonate-1,5-pentanediol-1,6-hexanediol ester diol (such as Asahi Chemical T5652) One or more. The use of polycarbonate polyol can ensure that the surface layer has a good velvety skin feel at a relatively low modulus, and at the same time is not sticky, meeting the demanding performance requirements of sofa leather, decorative leather, such as wear resistance, alcohol resistance, jungle resistance, and resistance to normal low temperature bending.

[0025] In a specific example, the small molecule diol is selected from one or more of diethylene glycol, ethylene glycol, 1,4-butanediol, neopentyl glycol, and hexanediol, preferably one or more of diethylene glycol, 1,4-butanediol, and ethylene glycol, and more preferably diethylene glycol and / or 1,4-butanediol.

[0026] In a specific example, the hydrophilic group-containing compound is a carboxyl-containing compound, preferably one or more of dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolacetic acid, and dihydroxysuccinic acid, more preferably dimethylolpropionic acid.

[0027] In a specific example, the catalyst is selected from organotin and / or organobismuth, preferably one or more of dibutyltin dilaurate (T-12), stannous octoate (T-9), Coscat83, organobismuth 2811, organobismuth 2808, and organobismuth 2010; among which organotin is a more efficient catalyst, and organobismuth is an environmentally friendly catalyst.

[0028] In a specific example, the post-chain extender is a small molecule organic amine compound selected from one or more of isophorone diamine, N-(2-hydroxyethyl)ethylenediamine and ethylenediamine, preferably N-(2-hydroxyethyl)ethylenediamine. The velvety surface layer is used in the varieties of sofa decorative leather, which basically adopts the process of water-based surface layer and solvent-free AB material foaming. The NCO in the AB material foaming is excessive. Small molecule organic amine compounds, especially N-(2-hydroxyethyl)ethylenediamine, are used as post-chain extenders. The hydroxyl groups contained in them will help the solvent-free AB material and the water-based surface layer to adhere firmly and establish long-lasting excellent performance.

[0029] In a specific example, the capping agent is a compound containing a hydroxyl group, selected from one or more of 2-amino-2-methyl-1-propanol and 2,2'-dihydroxydiethylamine, preferably 2,2'-dihydroxydiethylamine.

[0030] In a specific example, the neutralizing agent is selected from one or more of diethanolamine and triethanolamine, preferably triethanolamine, wherein the amino group can react with the residual NCO in the prepolymer to block the end, so that the molecular weight of the polyurethane is controlled within a certain range. If the molecular weight is too large, it cannot be effectively melted and penetrated to the bottom of the groove on the velvety release paper surface layer, and if the molecular weight is too small, it affects the basic physical properties of the synthetic leather surface layer such as wear resistance and dryness. In addition, the end-capping agent such as 2,2'-dihydroxydiethylamine and the hydroxyl group in the neutralizing agent such as triethanolamine can further strengthen the adhesion between the solvent-free AB material and the water-based surface layer.

[0031] In a specific example, the reaction in step 1) is performed at a temperature of 70-90°C, such as 70, 80, 90°C, preferably 70-80°C, and a time of 2-7h, such as 2, 4, 6h, preferably 2-5h;

[0032] Preferably, the reaction ends when the reaction reaches a value below the theoretical NCO% value, for example, the reaction ends when the NCO% is lower than 3.5%, such as 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5%, preferably 2.5-3.5%.

[0033] In a specific example, the chain extension reaction in step 2) is carried out for 5-50 min, for example, 5, 10, 30, 50 min, preferably 10-30 min; the neutralization reaction is not particularly limited in time, for example, it can be 1-30 min, preferably 15 min;

[0034] The reaction involved in step 2), including the chain extension reaction by adding the post-chain extender and the end-capping agent, and the neutralization reaction by adding the neutralizing agent, is not particularly limited in temperature. For example, it can be carried out at the temperature reached by adding the second part of the organic solvent for dilution and cooling. The temperature reached by the dilution and cooling is 25-50°C, such as 25, 35, 45°C, preferably 30-40°C.

[0035] In a specific example, the water is preferably deionized water, and the amount of water added should be such that the solid content of the aliphatic aqueous polyurethane dispersion is 35-45 wt %, preferably 38-42 wt %.

[0036] In a specific example, the shear dispersion is preferably high-speed shear dispersion, with a rotation speed of 1000-2500 rpm, such as 1000, 1500, 2000, 2500 rpm; the shear dispersion time is not particularly limited, for example, it can be 5-60 min, preferably 10-30 min, and most preferably about 15 min. The aliphatic aqueous polyurethane dispersion prepared by the above method of the present invention has an acid value of 20-50 mgKOH / g, a particle size of 100-400 nm, and a solid content of 35-45 wt%, which meets the physical property requirements of the aliphatic aqueous polyurethane dispersion in the composition of the present invention.

[0037] In a specific example of the present invention, the particle size of the polystyrene microspheres is 1-100 μm, such as 1, 10, 30, 50, 70, 90, 100 μm, preferably 5-60 μm; preferably, the polystyrene microspheres are selected from one or more of the PST-1-100 series of Zhongke Leiming and the PS1500-10000 series of Suzhou Zhiwei Nano Technology.

[0038] In a specific example of the present invention, the particle size of the silicone rubber powder is 1-100 μm, such as 1, 10, 30, 50, 70, 90, 100 μm, preferably 1-30 μm; preferably, the silicone rubber powder is selected from one or more of 9953, 2112 of Guangzhou Siloke and SMP-594 of Japan Shin-Etsu.

[0039] In a specific example of the present invention, the cross-linking agent is selected from one or more of aziridine cross-linking agents, carbodiimide cross-linking agents, and isocyanate cross-linking agents; preferably, the cross-linking agent is selected from CA01 of Shanghai Langyi.

[0040] In a specific example of the present invention, the defoaming agent is selected from one or more of silicone defoaming agents, mineral oil defoaming agents, and polyether polyol defoaming agents; preferably, the defoaming agent is selected from one or more of Efcona's PD-110 and BASF's 2360.

[0041] In a specific example of the present invention, the wetting agent is selected from one or more of acetylene glycol wetting agents; preferably, the wetting agent is selected from one or more of 104E of Air Chemistry and DF804 of Caiman Additive.

[0042] In a specific example of the present invention, the feel agent is selected from one or more of polyether modified silicones and polyether emulsified silicones; preferably, the feel agent is selected from one or more of Silok9155 and Silok3300 of Silok Chemical.

[0043] In a specific example of the present invention, the stabilizer is selected from one or more of the bentonite series; preferably, the stabilizer is selected from one or more of Laponite RD and RDS of Rockwood.

[0044] On the other hand, the present invention also provides a method for preparing the above-mentioned aqueous suede surface layer composition for synthetic leather, which can be prepared by conventional technical means in the art such as blending.

[0045] The following is only an exemplary preparation method, but it should not constitute any limitation on the preparation method of the composition of the present invention.

[0046] A method for preparing a water-based velvet-feeling surface layer composition for synthetic leather comprises the following steps: adding a wetting agent, a defoaming agent, a cross-linking agent, a hand-feeling agent, polystyrene microspheres and silicone rubber powder into an aliphatic water-based polyurethane dispersion under stirring conditions, and then adding a stabilizer to adjust the viscosity to 3000-8000 cps to obtain the water-based velvet-feeling surface layer composition for synthetic leather.

[0047] In a preferred example of the present invention, the raw materials are added in groups. First, a wetting agent, a defoaming agent, and a feel agent are added to the aliphatic aqueous polyurethane dispersion and stirred for a period of time, such as 30-60 minutes. Then, polystyrene microspheres and silicone rubber powder are added and stirred for a period of time, such as 30-60 minutes. Subsequently, a cross-linking agent is added and stirred for a period of time, such as 5-10 minutes. Finally, a stabilizer is added and stirred for a period of time, such as 10-30 minutes.

[0048] In addition, in the above preparation method, all steps not specifically described in the present invention can refer to the prior art.

[0049] On the other hand, the leather material prepared by using the aqueous suede surface layer composition of the synthetic leather of the present invention is widely used in the fields of clothing, bags, shoes, household goods, decorative goods, automotive supplies, etc., preferably in sofa leather and decorative leather.

[0050] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0051] (1) The synergistic use of polystyrene microspheres and silicone rubber powder in the composition of the present invention can achieve a comfortable effect close to the touch of the skin.

[0052] (2) The composition of the present invention is combined with an aliphatic water-based polyurethane dispersion and a stabilizer. During the drying process on the release paper, as the water evaporates in a fixed manner, the polystyrene microspheres and the silicone rubber powder are partially exposed. In the later stage of drying, the polyurethane resin is melted and cold-shrunk to achieve the purpose of the convex-concave design of the surface microstructure, thereby obtaining a polyurethane velvety surface layer.

[0053] (3) In the composition of the present invention, the aliphatic water-based polyurethane dispersion enables the water-based surface layer and the solvent-free AB material to be effectively and firmly bonded. The polystyrene microspheres, especially the PST series microspheres, have active carboxyl groups, and the silicone rubber powder, such as 9946, have active carboxyl groups, which are fully cross-linked with the polyurethane under the action of the cross-linking agent, further making the microspheres and the polyurethane main resin firmly bonded, and even after wear, the tactile style effect can still be maintained.

[0054] (4) The composition material of the present invention has good leveling properties, and the velvet surface layer has no shrinkage holes or bright spots, which solves the technical difficulties in the preparation of velvet surface layers in the water-based synthetic leather industry. The leather material prepared from the velvet surface layer has the advantages of good skin feel and good skin-friendly feel. At the same time, it has good resistance to bending, wear, alcohol rubbing, jungle test, etc., and can meet the physical property requirements of sofa leather and other similar fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1-5 These are the convex and concave surface effect diagrams formed by the aqueous polyurethane velvety surface layer compositions for synthetic leather prepared in Examples 1-5;

[0056] Figure 6-13 These are the surface effect diagrams formed by the aqueous polyurethane surface layer compositions prepared in Comparative Examples 1-8 respectively. DETAILED DESCRIPTION

[0057] The embodiments of the present invention are further described below in conjunction with examples, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the rights claimed by the present invention.

[0058] The sources of the main raw materials in the examples and comparative examples of the present invention are as follows. Other sources are obtained from common commercial channels unless otherwise specified:

[0059] Polycarbonate-1,4-butanediol-1,6-hexanediol ester diol: Asahi Chemical, GE502, Mn=2000;

[0060] Polycarbonate-1,6-hexanediol ester diol: Asahi Chemical, S6002, Mn=2000;

[0061] Polycarbonate-1,5-pentanediol-1,6-hexanediol ester diol: Asahi Chemical, T5652, Mn=2000;

[0062] IPDI: Wanhua Chemical;

[0063] HMDI: Wanhua Chemical;

[0064] HDI: Wanhua Chemical;

[0065] Dimethylolpropionic acid: Shilong Industrial;

[0066] Neopentyl glycol: Wanhua Chemical;

[0067] 1,4-Butanediol: Wanhua Chemical;

[0068] Organobismuth 2010: America's Leading Chemistry;

[0069] Organobismuth 2811: Leading Chemistry;

[0070] Organic Bismuth 2808: Leading Chemistry;

[0071] Acetone: Sinopharm Group;

[0072] AMP95: contains 5% water-2-amino-2-methyl-1-propanol, Dow Chemical;

[0073] N-(2-Hydroxyethyl)ethylenediamine: Sinopharm Group;

[0074] Triethanolamine: Sinopharm Group;

[0075] Triethylamine: Sinopharm Group.

[0076] Preparation Example 1-4: Aliphatic waterborne polyurethane dispersion ①-④

[0077] Aliphatic waterborne polyurethane dispersions ①-④ were prepared according to the proportions shown in Table 1 (the amount of each component in the table represents g, and the amount in brackets represents mol). The preparation process includes:

[0078] 1) adding the dehydrated reactants polyol, aliphatic isocyanate, hydrophilic group-containing compound, small molecule diol, catalyst, and the first part of organic solvent (the amount is recorded as 1) into a 1L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, stirring and heating to react for 1, until the NCO% reaches below the theoretical value;

[0079] 2) Add the second part of organic solvent (the amount is recorded as 2) to dilute and cool to 40°C, then add the post-chain extender and the end-capping agent while maintaining the temperature to carry out chain extension reaction for about 10-30 minutes, then add the neutralizer to carry out neutralization reaction for about 5 minutes, then add deionized water and high-speed shear dispersion at a speed of 1000-2500 rpm for 10 minutes, and finally completely remove the organic solvent by distillation to obtain waterborne polyurethane dispersions ①-④, whose acid value, particle size and solid content are shown in Table 2.

[0080] Table 1 Ratios and preparation conditions of Preparation Examples 1-4

[0081]

[0082]

[0083] Table 2 Acid value, particle size, solid content of aliphatic waterborne polyurethane dispersions ①-④

[0084]

[0085]

[0086] Examples 1-5

[0087] The aqueous polyurethane velvety surface layer compositions for synthetic leather of Examples 1 to 5 were prepared according to the proportions shown in Table 3 (the amounts of each component in the table represent parts by weight). The preparation process includes:

[0088] According to the formula, weigh the aliphatic water-based polyurethane dispersion, add it into a stirring kettle, add the wetting agent, defoaming agent and feel agent at a speed of 800 rpm and stir for 10 minutes, add polystyrene microspheres and silicone rubber powder and stir for 5 minutes, add the cross-linking agent and stir for 3 minutes, finally add the stabilizer and stir for 5 minutes to adjust to a suitable viscosity, to obtain a water-based velvety surface slurry composition for synthetic leather.

[0089] Table 3 Proportions and preparation conditions of Examples 1-5

[0090]

[0091]

[0092] Comparative Example 1

[0093] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the polystyrene microspheres PST-5 and silicone rubber powder 2112 were not added, and other operations and parameters remained unchanged to obtain the waterborne polyurethane surface layer composition.

[0094] Comparative Example 2

[0095] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the amount of polystyrene microspheres PST-5 was increased to 60 parts, and the amount of silicone rubber powder 2112 was increased to 30 parts. Other operations and parameters remained unchanged to obtain a waterborne polyurethane surface layer composition.

[0096] Comparative Example 3

[0097] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the stabilizer RD was completely replaced with 1.6 parts of thickener Wanhua U605, and other operations and parameters remained unchanged to obtain the waterborne polyurethane surface layer composition.

[0098] Comparative Example 4

[0099] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the polystyrene microspheres PST-5 were not added, and other operations and parameters remained unchanged to obtain the waterborne polyurethane surface layer composition.

[0100] Comparative Example 5

[0101] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the polystyrene microspheres PST-5 were replaced with an equal amount of 1250 mesh kaolin filler, and other operations and parameters remained unchanged to obtain the waterborne polyurethane surface layer composition.

[0102] Comparative Example 6

[0103] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the silicone rubber powder 2112 was not added, and other operations and parameters remained unchanged to obtain the waterborne polyurethane surface layer composition.

[0104] Comparative Example 7

[0105] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the silicone rubber powder 2112 was replaced by an equal amount of 325 mesh fiber powder, and other operations and parameters remained unchanged to obtain the waterborne polyurethane surface layer composition.

[0106] Comparative Example 8

[0107] The raw materials and proportions of the waterborne polyurethane surface layer composition were prepared by referring to Example 1, except that the aliphatic waterborne polyurethane dispersion ① was replaced with an equal amount of Wanhua Chemical 3966 (TDI and ppg2000 system, solid content: 35%, particle size: 115nm), other operations and parameters remained unchanged, and a waterborne polyurethane surface layer composition was prepared.

[0108] The waterborne polyurethane surface layer compositions of Examples 1-5 and Comparative Examples 1-8 were used to prepare polyurethane surface layers according to the following method:

[0109] The aqueous polyurethane surface layer composition is scraped onto the velvet release paper with a coating thickness of 0.12 mm, and is dried at a set temperature of 90-110-125 degrees in a stepwise manner. After separating the release paper, a conventional solvent-free AB material for sofa leather is scraped on the back, and the sofa cover is attached and dried to obtain the product.

[0110] Figure 1-5 The convex and concave surface effect diagrams of the aqueous polyurethane velvety surface layer compositions for synthetic leather prepared in Examples 1-5 respectively show that:

[0111] Example Figures 1 to 5 The convexity is stronger, among which, Figure 2 Because there are more big balls, the display is larger and the feel will be stronger. Figure 5 The microspheres are small, are more surrounded by resin, and have a relatively weak feel.

[0112] Comparative Example Figure 6-13 ,in, Figure 6 It can be seen that the surface has no roughness and the leather suede effect is weak; Figure 7 It can be seen that the surface roughness is better, but other properties are worse and cannot meet the use requirements; Figure 8 , Fig. 9 , Fig.11 and Fig.13 It can be seen that the surface roughness is relatively weak, and the leather velvet feel is weak; Fig.10 and Fig.12 It can be seen that the surface lacks roughness and the leather suede feel is weak.

[0113] The performance tests were conducted on the polyurethane surface layers prepared in the above embodiments and comparative examples, and the test results are shown in Table 4.

[0114] Table 4 Polyurethane surface performance test results

[0115]

[0116]

[0117] The test method is as follows:

[0118] Surface effect: Professionals shall observe under a standard light box to check whether there are bright spots, white spots and other abnormal defects.

[0119] Velvet feel scoring method: Professionals compare and score by hand touch, which is divided into 6 levels, namely 0, 1, 2, 3, 4, and 5 points, among which 5 points is the best.

[0120] Bending test method: Cut 3 pieces of 4×7cm in warp and weft directions, test them in normal temperature bending and low temperature bending equipment respectively, record the number of bending times, and observe whether there are cracks.

[0121] Wear resistance test method: Cut 3 pieces in each of the warp and weft directions. After the test, observe the changes on the surface of the tested sample. If it exceeds the size of a mung bean, it is judged as unqualified. Record the number of times each reaches, remove the maximum and minimum values, and record the average number of wear times.

[0122] Alcohol rub resistance test method: wet and dry rub color fastness meter, 95% ethanol, rub back and forth 20 times, observe whether there is any abnormality on the surface, there are 5 scoring standards from bad to excellent, namely 1, 2, 3, 4 and 5.

[0123] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A water-based suede surface layer composition for synthetic leather, characterized in that: Prepared from the following components in parts by weight: Preferably, the aqueous suede surface layer composition for synthetic leather is prepared from the following components in parts by weight:

2. The aqueous suede surface layer composition for synthetic leather according to claim 1, characterized in that: The aliphatic waterborne polyurethane dispersion has an acid value of 20-50 mgKOH / g, a particle size of 100-400 nm, and a solid content of 35-45 wt%.

3. The aqueous suede surface layer composition for synthetic leather according to claim 1 or 2, characterized in that: The aliphatic waterborne polyurethane dispersion is prepared by the following steps: 1) adding reactive polyol, aliphatic isocyanate, hydrophilic group-containing compound, small molecule diol, catalyst, and the first part of organic solvent into a nitrogen-protected reactor, and heating to react; 2) adding a second portion of organic solvent to dilute and cool, adding a post-chain extender and a capping agent to carry out a chain extension reaction, then adding a neutralizing agent to carry out a neutralization reaction, then adding water to carry out shear dispersion, and finally raising the temperature to remove the organic solvent to obtain an aliphatic waterborne polyurethane dispersion.

4. The aqueous suede surface layer composition for synthetic leather according to claim 3, characterized in that: The raw materials include, by weight: 100-200 parts of reactive polyol, 30-60 parts of aliphatic isocyanate, 100-300 parts of organic solvent, 20-50 parts of hydrophilic group-containing compound, 1-5.5 parts of small molecule diol, 10-30 parts of post-chain extender, 10-30 parts of end-capping agent, and 10-30 parts of neutralizer; preferably, 120-180 parts of reactive polyol, 40-60 parts of aliphatic isocyanate, 150-250 parts of organic solvent, 25-40 parts of hydrophilic group-containing compound, 1.5-3.5 parts of small molecule diol, 14-22 parts of post-chain extender, 15-25 parts of end-capping agent, and 15-25 parts of neutralizer; Preferably, the amount of the catalyst used is 0.05-0.5wt% based on the total mass of the reactants, wherein the reactants include reactive polyols, aliphatic isocyanates, hydrophilic group-containing compounds, and small molecule diols.

5. The aqueous suede surface layer composition for synthetic leather according to claim 3, characterized in that: Based on the total mass of the reactants, the first part of the organic solvent is added in an amount of 5-30wt%, and the second part of the organic solvent is added in an amount of 60-90wt%, wherein the reactants include reactive polyols, aliphatic isocyanates, hydrophilic group-containing compounds, and small molecule diols; and / or The organic solvent is selected from ketone solvents, preferably one or more of acetone and butanone; and / or The aliphatic isocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, butylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, diisocyanatomethylcyclohexane, and diisocyanatomethyltricyclodecane; and / or The reactive polyol has a number average molecular weight of 600-4000, preferably a polycarbonate polyol with a number average molecular weight of 1000-2000; and / or The small molecule diol is selected from one or more of diethylene glycol, ethylene glycol, 1,4-butanediol, neopentyl glycol, and hexanediol, preferably one or more of diethylene glycol, 1,4-butanediol, and ethylene glycol; and / or The hydrophilic group-containing compound is a carboxyl-containing compound, preferably one or more of dimethylolpropionic acid, dimethylolbutyric acid, dimethylolacetic acid, and dihydroxysuccinic acid; and / or The catalyst is selected from organotin and / or organobismuth; and / or The post-chain extender is a small molecule organic amine compound, preferably one or more of isophoronediamine, N-(2-hydroxyethyl)ethylenediamine and ethylenediamine; and / or The end-capping agent is a compound containing a hydroxyl group, preferably one or more of 2-amino-2-methyl-1-propanol and 2,2'-dihydroxydiethylamine; and / or The neutralizing agent is selected from one or more of diethanolamine and triethanolamine.

6. The aqueous suede surface layer composition for synthetic leather according to any one of claims 1 to 5, characterized in that: The particle size of the polystyrene microspheres is 1-100 μm, preferably 5-60 μm; preferably, the polystyrene microspheres are selected from one or more of the PST-1-100 series of Zhongke Leiming and the PS1500-10000 series of Suzhou Zhiwei Nanotechnology.

7. The aqueous suede surface layer composition for synthetic leather according to any one of claims 1 to 6, characterized in that: The particle size of the silicone rubber powder is 1-100 μm, preferably 1-30 μm; preferably, the silicone rubber powder is selected from one or more of 9953 and 2112 of Guangzhou Siloke and SMP-594 of Japan Shin-Etsu.

8. The aqueous suede surface layer composition for synthetic leather according to any one of claims 1 to 7, characterized in that: The cross-linking agent is selected from one or more of aziridine cross-linking agents, carbodiimide cross-linking agents, and isocyanate cross-linking agents; preferably, the cross-linking agent is selected from CA01 of Shanghai Langyi; and / or The defoamer is selected from one or more of silicone defoamers, mineral oil defoamers, and polyether polyol defoamers; preferably, the defoamer is selected from one or more of Efcona's PD-110 and BASF's 2360; and / or The wetting agent is selected from one or more of acetylene glycol wetting agents; preferably, the wetting agent is selected from one or more of 104E of Air Chemistry and DF804 of Caiman Additive; and / or The hand feeling agent is selected from one or more of polyether modified silicones and polyether emulsified silicones; preferably, the hand feeling agent is selected from one or more of Silok9155 and Silok3300 of Silok Chemical. The stabilizer is selected from one or more of the bentonite series; preferably, the stabilizer is selected from one or more of Laponite RD and RDS of Rockwood.

9. A method for preparing the aqueous suede surface layer composition for synthetic leather according to any one of claims 1 to 8, characterized in that the steps include: Under stirring conditions, a wetting agent, a defoaming agent, a crosslinking agent, a hand feeling agent, polystyrene microspheres, and silicone rubber powder are added to the aliphatic aqueous polyurethane dispersion, and then a stabilizer is added to adjust the viscosity to 3000-8000 cps to obtain the aqueous velvety surface layer composition for synthetic leather.

10. The preparation method according to claim 9, characterized in that: The raw materials are added in groups. First, a wetting agent, a defoaming agent, and a feel agent are added to the aliphatic waterborne polyurethane dispersion and stirred for a period of time. Then, polystyrene microspheres and silicone rubber powder are added and stirred for a period of time. Subsequently, a cross-linking agent is added and stirred for a period of time. Finally, a stabilizer is added and stirred for a period of time.

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