Uncertain island high resilience microfiber polyurethane synthetic leather

Abstract

The invention provides an indefinite island high-resilience superfine fiber polyurethane synthetic leather, belonging to the technical field of synthetic leather. The invention first uses LDPE as a sea phase and PA6 as an island phase, and adds a certain amount of barium sulfate and calcined clay in the island phase to prepare indefinite island high-resilience superfine fibers, and then uses a needle punching method to make the indefinite island high-resilience superfine fibers into a non-woven fabric, and then sequentially impregnates the DMF solution of polyurethane, coagulates and washes in an aqueous solution of DMF, extracts and reduces the amount of toluene, heat treats, and coats the surface with polyurethane slurry, and finally obtains the indefinite island high-resilience superfine fiber polyurethane synthetic leather through post-finishing. The obtained synthetic leather has a softer feel, good elasticity, strong three-dimensional sense, is closer to genuine leather, has good strength, elasticity and heat resistance, and has high peeling strength.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic leather, and in particular relates to an indefinite island high-resilience ultrafine fiber polyurethane synthetic leather. Background Art

[0002] Superfine fiber synthetic leather is a composite of superfine fiber three-dimensional interweaving and polyurethane with microporous structure. Its microstructure and performance are similar to natural leather. It is the synthetic leather closest to leather in the world. It has a very wide range of applications due to its excellent performance, diverse products, and the ability to replace leather. Superfine fiber is the most basic component of superfine leather. It simulates natural fiber in composition and structure, making superfine leather have a similar appearance, feel and internal structure to leather. It is the foundation and core technology of the synthetic leather industry. Sea-island type superfine fiber is a special fiber made by blending or composite spinning of two or more thermodynamically incompatible polymers, in which one polymer (dispersed phase, i.e., island phase, generally PA6) is dispersed in another polymer (continuous phase, i.e., sea phase, generally LDPE) in the form of microfibers. According to the island distribution of the dispersed phase, the sea-island type fiber is divided into fixed island fiber and unfixed island fiber.

[0003] Fixed island fiber is made of polymer PA6 (nylon 6) and COPET (alkali soluble polyester chips) melted separately through a twin-screw composite spinning machine and entering the island-type spinning assembly. The island phase and the sea phase are respectively ejected through their own paths at the outlet of the spinneret to form fixed island-type sea-island fiber. Its island phase and sea phase are continuous and evenly distributed in the length direction of the fiber, and the number of islands is fixed. Unfixed island fiber is generally made of PA6 and LDPE mixed at a certain temperature and conditions, melted and blended by the same screw extruder, and then ejected through a metering pump and a spinning assembly to form unfixed island ultrafine fibers, whose island phases are discontinuous and unfixed. Unfixed island high-resilience ultrafine fiber polyurethane synthetic leather has a unique appearance and performance. It is superior to ordinary PU leather and natural leather in terms of mildew resistance, moth resistance, tensile strength, tear strength, breathability, etc. At the same time, it has the advantages of consistent appearance texture, good color fastness, convenient cutting and low loss in use. It is widely used by consumers, especially in the fields of shoemaking, luggage, clothing, furniture, home decoration, and automotive interiors.

[0004] The indefinite island high resilience microfiber polyurethane synthetic leather is made by dipping the indefinite island high resilience microfiber nonwoven fabric in a polyurethane DMF (dimethylformamide) solution, then soaking it in a coagulation liquid DMF aqueous solution, coagulating and foaming it, and then using an inorganic or organic solvent to dissolve the "sea" part of the island-in-the-sea type short fiber. At present, research on indefinite island high resilience microfiber polyurethane synthetic leather has made certain progress.

[0005] For example, patent CN104313894A discloses a method for preparing sea-island microfiber PU synthetic leather, which uses the manufactured fixed island and irregular island microfiber bass of sea-island microfiber, and transfers and bonds the wet PU microporous foaming film with the fixed island and irregular island microfiber bass of sea-island microfiber, and uses the membrane transfer technology to manufacture a PU microfiber synthetic leather that can be widely post-processed. This overcomes the defect that the current microfiber PU synthetic leather cannot achieve effective leather grain embossing processing technology by coating the wet polyurethane resin foaming layer in the existing processing technology.

[0006] For example, CN102517920A discloses a method for making an indefinite island ultrafine fiber artificial leather, which uses a melt spinning method to co-spin HDPE and nylon into fibers of a certain fineness, and then uses a needle punching method to make a non-woven fabric, which is impregnated with a polyurethane resin, solidified, dried, and then enters a toluene extraction tank, which contains a co-solvent of toluene and diethylene glycol or a co-solvent of toluene, diethylene glycol and oleic acid amide. After passing through the toluene extraction tank, ultrafine fibers are obtained, and ultrafine artificial leather is obtained after mechanical softening. The obtained ultrafine artificial leather has a soft and smooth feel, a strong leather feel, and high added value.

[0007] However, there are certain defects in the production process of indefinite island ultrafine fibers and the process of producing synthetic leather using indefinite island high resilience ultrafine fibers. For example, when preparing island fibers using PA6 as the island phase and LDPE as the sea phase, although high molecular weight PA6 can improve mechanical properties, the viscosity is too large and the viscosity difference with LDPE is too large, and the melt spinning process is unstable. Therefore, it is necessary to improve the preparation process of indefinite island ultrafine fibers. In the process of producing synthetic leather using indefinite island high resilience ultrafine fibers, generally, non-woven fabrics, heat setting, impregnation with polyurethane slurry, coagulation, washing, solvent extraction, waterproofing, coating with polyurethane slurry, and finishing are performed. After the waterproofing, a water film is formed on the surface of the base fabric, which is not conducive to the coating of polyurethane slurry in the next step. The peel strength between the impregnation layer and the coating layer is low, and the mechanical properties need to be further improved. Summary of the invention

[0008] The purpose of the present invention is to make up for the deficiencies of the prior art and provide an indefinite island high-resilience ultrafine fiber polyurethane synthetic leather, which has high peeling strength and excellent mechanical properties and heat resistance.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] An indefinite island high resilience ultrafine fiber, with LDPE as the sea phase and PA6 as the island phase; wherein,

[0011] The island phase also contains barium sulfate and calcined clay;

[0012] The content of barium sulfate is 0.6-1% of the mass of PA6, and the content of calcined clay is 2-3% of the mass of PA6.

[0013] Furthermore, the density of the LDPE is 0.910-0.935 g / cm 3 .

[0014] Furthermore, the content of barium sulfate is 0.8% of the mass of PA6, and the content of calcined clay is 2.6% of the mass of PA6.

[0015] Furthermore, in the indefinite-island high-resilience ultrafine fiber, the mass ratio of the sea phase to the island phase is 40-50:50-60.

[0016] The method for preparing the above-mentioned indefinite island high resilience ultrafine fiber comprises the following steps:

[0017] Barium sulfate, calcined clay and PA6 are ground and mixed with water, dried and added into a twin-screw machine for melt blending, and LDPE is added and melt blended and spun to obtain indefinite island high resilience ultrafine fibers.

[0018] Furthermore, the melt spinning method conditions are: spinning temperature 230-265°C, spinning speed 500-1200m / min, drafting multiple 2-4 times, and drafting temperature 85-90°C.

[0019] Although the strength of the fiber can be improved by using PA6 as the island phase to prepare the adventitious island ultrafine fiber, PA6 has a high molecular weight and high viscosity, and the viscosity difference with LDPE is too large, and the melt fluidity is poor, which makes the spinning process of the sea island fiber unstable or difficult to form. The present invention uses PA6, barium sulfate and calcined clay as the island phase. Compared with the traditional PA6 as the adventitious island, the addition of barium sulfate and calcined clay can reduce the viscosity of PA6 and increase the spinning formability; and barium sulfate, calcined clay and PA6 are first ground with water and then melt-blended, which improves the compatibility with PA6, and can avoid the instability of fiber performance caused by the unevenness of the island phase, thereby improving the strength and elasticity of the fiber and improving the performance of the final product synthetic leather.

[0020] The application of the above-mentioned indefinite island high resilience ultrafine fiber in the preparation of synthetic leather.

[0021] A method for preparing an indefinite island high-resilience ultrafine fiber polyurethane synthetic leather comprises the following steps:

[0022] (1) The indefinite island high resilience ultrafine fiber is made into a non-woven fabric by needle punching;

[0023] (2) dipping the nonwoven fabric in a DMF solution of polyurethane, then placing it in an aqueous DMF solution for coagulation, and washing with water;

[0024] (3) extracting and reducing with toluene solution to produce a synthetic leather semi-finished product;

[0025] (4) Heat treatment of synthetic leather semi-finished products and coating of polyurethane slurry on the surface;

[0026] (5) Finally, after finishing, the indefinite island high resilience microfiber polyurethane synthetic leather is obtained.

[0027] Furthermore, in step (2), the mass fraction of polyurethane in the DMF solution of polyurethane is 25-35%, and the mass fraction of DMF in the DMF aqueous solution is 12-16%.

[0028] Furthermore, in step (3), the temperature during the extraction reduction process is 85-90°C.

[0029] Furthermore, in step (4), the heat treatment process is: first keep warm at 60-70°C for 10-20 minutes, then heat up to 100-110°C and keep warm for 3-5 minutes. The present invention performs heat treatment before coating the polyurethane slurry, which helps to uniformly coat the subsequent polyurethane slurry, promotes the penetration of the polyurethane slurry on the surface of the non-woven fabric, reduces the use of penetrants, increases adhesion, and reduces costs. The polyurethane slurry forms a thin film on the surface of the non-woven fabric, and the product feels softer, has good elasticity, a strong three-dimensional sense, is closer to genuine leather, and helps to improve the strength of synthetic leather.

[0030] Furthermore, in step (4), the thickness of the coated polyurethane slurry is 0.8-1.4 mm.

[0031] Furthermore, in step (4), the polyurethane slurry comprises: 100 parts of polyurethane resin, 10-20 parts of higher fatty acid rosin ester resin, 2-5 parts of penetrant, 5-10 parts of color paste, 1-3 parts of polyvinyl pyrrolidone, and 50-80 parts of DMF.

[0032] The higher fatty acid rosin ester resin is produced by the following method:

[0033] The polymerized rosin is crushed, melted at 220-240°C, a catalyst is added, and then a polyol is added. The temperature is kept high and the reaction is carried out for 3-6 hours. Then, a higher fatty acid is added and the reaction is continued for 4-7 hours. The resin is obtained by cooling.

[0034] Furthermore, during the preparation of the higher fatty acid rosin ester resin, the heat preservation time is 1-2 hours.

[0035] Furthermore, in the preparation process of the higher fatty acid rosin ester resin, the catalyst is at least one of phosphorus-containing inorganic acid, phosphorus-containing inorganic salt, phosphorus-containing organic salt, sulfur-containing inorganic salt, phenol sulfide, and monocyclic aromatic hydrocarbon derivatives, including but not limited to phosphoric acid, phosphorous acid, and hypophosphorous acid; the phosphorus-containing inorganic salt includes but is not limited to calcium phosphate, sodium phosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, sodium sulfate, magnesium sulfate, calcium sulfite, benzoic acid, benzenesulfonic acid, p-hydroxybenzenesulfonic acid, and p-toluenesulfonic acid. The amount of the catalyst added is 0.5-2% of the mass of the polymerized rosin.

[0036] Furthermore, in the preparation process of the higher fatty acid rosin ester resin, the polyols are pentaerythritol and xylitol, and the added amounts of pentaerythritol and xylitol are 10-12.7% and 1.5-2% of the mass of the polymerized rosin, respectively.

[0037] Furthermore, during the preparation of the higher fatty acid rosin ester resin, the heating temperature is 270-275°C.

[0038] Furthermore, in the preparation process of the higher fatty acid rosin ester resin, the higher fatty acid is myristic acid and lauroleic acid in a mass ratio of 3-4:1; and the added amount of the higher fatty acid is 18-25% of the mass of the polymerized rosin.

[0039] The present invention utilizes polymerized rosin to react with pentaerythritol, xylitol and higher fatty acid to prepare rosin ester resin, pentaerythritol and long-chain fatty acid are introduced into polymerized rosin molecular chain, the tail chain length and flexibility of polymerized rosin are increased, the glass transition temperature of polymer is effectively increased, the movement of molecular chain in high frequency region is reduced and the movement of molecular chain in low frequency region is increased, the rigidity of polymerized rosin ester is reduced to a greater extent, and the effective dispersion in polyurethane slurry is increased, the bonding between polyurethane slurry and non-woven fabric material is effectively improved, and obvious coating interface and even delamination and other problems will not occur, the product has high peeling strength and prolonged service life. By controlling the amount of pentaerythritol and higher fatty acid, the rigidity and flexible chain segment ratio of polymerized rosin resin are regulated, the elasticity of synthetic leather is also improved, the heat resistance can be improved, the thermal stability is good, deformation is not easy to occur, the synthetic leather can be used as clothing fabric, and can also be used as automotive leather material, thereby widening the application scope of common polymerized rosin resin to a greater extent.

[0040] Furthermore, the penetrant is at least one of succinate sulfonate and fatty alcohol polyoxyethylene ether, including but not limited to at least one of diisooctyl sodium sulfosuccinate, ditridecyl sodium sulfosuccinate, and isobutylphenoxy polyoxyethylene ethanol.

[0041] Furthermore, the polyurethane resin is polyester polyurethane or polyether polyurethane.

[0042] Furthermore, in step (5), the post-finishing includes steps such as peeling, grinding, heat treatment, washing, and drying, which are all conventional methods.

[0043] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0044] 1. The indefinite island high resilience ultrafine fiber provided by the present invention is prepared by using PA6 as an island phase and adding a certain amount of barium sulfate and calcined clay, and using LDPE as a sea phase, which makes up for the defect of poor spinnability when PA6 is used as an island phase; and the barium sulfate, calcined clay and PA6 are first ground with water and then melt-blended, which improves the compatibility with PA6, can avoid the instability of fiber performance caused by the unevenness of the island phase, and can further improve the strength and elasticity of the fiber.

[0045] 2. The indefinite island high-resilience ultrafine fiber polyurethane synthetic leather provided by the present invention is firstly obtained by needle-punching the indefinite island high-resilience ultrafine fiber into a non-woven fabric, then impregnated in a DMF solution of polyurethane, coagulated, washed, extracted with toluene, heat-treated, coated with polyurethane slurry on the surface, and finally obtained by post-finishing. The various steps in the present invention cooperate with each other, and the obtained synthetic leather has a softer feel, good elasticity, strong three-dimensional sense, is closer to genuine leather, and has good strength, elasticity and heat resistance.

[0046] 3. The present invention performs heat treatment before coating the polyurethane slurry, which helps to uniformly coat the subsequent polyurethane slurry, promotes the penetration of the polyurethane slurry on the surface of synthetic leather, reduces the use of penetrants, reduces costs, and enables the polyurethane slurry to form a thin film on the surface of the non-woven fabric. The product feels softer, has good elasticity, a strong three-dimensional sense, is closer to genuine leather, and helps to improve the strength of synthetic leather.

[0047] 4. The present invention utilizes polymerized rosin to react with pentaerythritol, xylitol, and higher fatty acids to prepare rosin ester resin. Pentaerythritol and long-chain fatty acids are introduced into the polymerized rosin molecular chain, which increases the tail chain length and flexibility of the polymerized rosin, effectively improves the glass transition temperature of the polymer, reduces the movement of the molecular chain in the high-frequency region and increases the movement of the molecular chain in the low-frequency region, reduces the rigidity of the polymerized rosin ester to a greater extent, and increases the effective dispersion in the polyurethane slurry, effectively improves the bonding between the polyurethane slurry and the non-woven fabric material, does not have obvious coating interface, even delamination and other problems, the product has high peeling strength and extended service life. By controlling the amount of pentaerythritol and higher fatty acids, regulating the ratio of the rigid and flexible segments of the polymerized rosin resin, it is also helpful to improve the elasticity of the synthetic leather, and can improve the heat resistance, good thermal stability, and is not easy to deform, so that the synthetic leather can be used as clothing fabrics and also as automotive leather materials, thereby broadening the scope of use of ordinary polymerized rosin resin to a greater extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a flow chart of the preparation method of the indefinite island high resilience ultrafine fiber polyurethane synthetic leather in Example 1 of the present invention;

[0049] Figure 2 is an infrared spectrum of the higher fatty acid rosin ester resin in Example 1 of the present invention; curve a in the figure represents polymerized rosin, curve b represents polymerized rosin modified with monopentaerythritol, and curve c represents the higher fatty acid rosin ester resin;

[0050] Figure 3 It is a schematic diagram of the heat resistance test results of the indefinite island high resilience ultrafine fiber polyurethane synthetic leather of the present invention. DETAILED DESCRIPTION

[0051] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is only an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the invention of the present invention based on the disclosed content, and they should also fall within the scope of the present invention.

[0052] The present invention is further described below by way of specific examples. Unless otherwise specified, the various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels.

[0053] Example 1

[0054] Preparation method of indefinite island high resilience microfiber polyurethane synthetic leather (flow chart as shown in Figure 1 ), comprising the following steps:

[0055] S1. Preparation of indefinite island high resilience ultrafine fibers:

[0056] 50 parts of PA6, 0.3 parts of barium sulfate and 1 part of calcined clay were ground and mixed with water, dried and added to a twin-screw machine for melt blending. LDPE (density 0.925 g / cm2) was added according to the mass ratio of sea phase to island phase of 40:60. 3 ), melt blending and spinning to obtain indefinite island high resilience ultrafine fibers; the melt spinning conditions are: twin screw machine temperature 230-265°C, spinning speed spinning speed is 500m / min, drafting multiple is 4 times, and drafting temperature is 85°C.

[0057] S2. Nonwoven fabric made by needle punching:

[0058] The indefinite island high resilience microfiber is made into non-woven fabric by needle punching, and the thickness of the non-woven fabric is 1.6mm;

[0059] S3, DMF solution for impregnation of polyurethane:

[0060] The nonwoven fabric was immersed in a DMF solution of polyurethane (the mass fraction of polyurethane was 25%), then placed in an aqueous solution of DMF (the mass fraction of DMF was 12%) for coagulation, and then washed with water;

[0061] S4, toluene extraction reduction:

[0062] The non-woven fabric is extracted and reduced with a toluene solution at a temperature of 85°C to produce a synthetic leather semi-finished product;

[0063] S5. Coating polyurethane slurry:

[0064] The synthetic leather semi-finished product is heat-treated, first at 60°C for 20 minutes, then heated to 100°C for 3 minutes; then coated with polyurethane slurry to form a polyurethane film with a thickness of 1.2 mm; the polyurethane slurry is prepared by mixing 100 parts of polyurethane resin, 10 parts of higher fatty acid rosin ester resin, 2 parts of isobutylphenoxy polyoxyethylene ethanol, 5 parts of color paste, 1 part of polyvinyl pyrrolidone, and 60 parts of DMF;

[0065] S6, finishing:

[0066] The synthetic leather coated with polyurethane slurry is finally finished to obtain indefinite island high resilience superfine fiber polyurethane synthetic leather.

[0067] In this embodiment, the higher fatty acid rosin ester resin is prepared by the following method:

[0068] 100 parts of polymerized rosin were crushed and melted at 220°C, 0.5 parts of p-hydroxybenzenesulfonic acid were added, and then 10 parts of pentaerythritol and 2 parts of xylitol were added, and the mixture was kept warm for 2 hours, and the temperature was raised to 270°C for reaction for 5 hours, 18 parts of higher fatty acids (myristic acid and lauroleic acid in a mass ratio of 3:1) were added and reacted for 6 hours, and the resin was obtained by cooling.

[0069] The higher fatty acid rosin ester resin obtained in this example was measured using a FTIR-8400S Fourier transform infrared spectrometer (Shimadzu, Japan) and a KBr pellet was used to measure the sample. The wave number range of the measurement was 4000-500 cm -1 , the results are as follows Figure 2 As shown in the figure, curve a represents polymerized rosin, curve b represents polymerized rosin modified with monopentaerythritol, and curve c represents higher fatty acid rosin ester resin; by comparing curves a and b, it can be seen that in curve b, at 3450cm -1 The stretching vibration peak of OH bond appears near 2530cm -1 and 938cm -1 The characteristic absorption peak near 1617cm -1 、1112cm -1The characteristic peaks belonging to the esterification products appeared near 3450cm -1 The stretching vibration peak of the OH bond near 825cm -1 、718cm -1 The absorption peak near is significantly enhanced. This is because the higher fatty acids are connected to the polymerized rosin, which introduces long-chain alkyl groups into the entire molecule, resulting in the strengthening of the external bending vibration of CH in the higher fatty acid rosin ester resin.

[0070] Example 2

[0071] The method for preparing indefinite island high-resilience ultrafine fiber polyurethane synthetic leather comprises the following steps:

[0072] S1. Preparation of indefinite island high resilience ultrafine fibers:

[0073] 50 parts of PA6, 0.4 parts of barium sulfate and 1.3 parts of calcined clay were ground and mixed with water, dried and added to a twin-screw machine for melt blending. LDPE (density 0.910 g / cm2) was added according to the mass ratio of sea phase to island phase of 45:55. 3 ), melt blending and spinning to obtain indefinite island high resilience ultrafine fibers; the melt spinning conditions are: twin screw machine temperature 230-265°C, spinning speed spinning speed is 900m / min, stretching multiple is 4 times, and stretching temperature is 90°C.

[0074] S2. Nonwoven fabric made by needle punching:

[0075] The indefinite island high resilience microfiber is made into non-woven fabric by needle punching, and the thickness of the non-woven fabric is 1.6mm;

[0076] S3, DMF solution for impregnation of polyurethane:

[0077] The nonwoven fabric was immersed in a polyurethane DMF solution (the mass fraction of polyurethane was 28%), then placed in a DMF aqueous solution (the mass fraction of DMF was 14%) for coagulation, and then washed with water;

[0078] S4, toluene extraction reduction:

[0079] The non-woven fabric is extracted and reduced with a toluene solution at a temperature of 90°C to produce a synthetic leather semi-finished product;

[0080] S5. Coating polyurethane slurry:

[0081] The synthetic leather semi-finished product is heat-treated, first at 65°C for 20 minutes, then heated to 110°C for 5 minutes; then coated with polyurethane slurry with a thickness of 1.2 mm; the polyurethane slurry is prepared by mixing 100 parts of polyurethane resin, 16 parts of higher fatty acid rosin ester resin, 3.5 parts of sodium diisooctyl sulfosuccinate, 5 parts of color paste, 2.4 parts of polyvinyl pyrrolidone, and 80 parts of DMF;

[0082] S6, finishing:

[0083] The synthetic leather coated with polyurethane slurry is finally finished to obtain indefinite island high resilience superfine fiber polyurethane synthetic leather.

[0084] In this embodiment, the higher fatty acid rosin ester resin is prepared by the following method:

[0085] 100 parts of polymerized rosin were crushed and melted at 230°C, 2 parts of sodium phosphite were added, and then 11.6 parts of pentaerythritol and 1.8 parts of xylitol were added, and the mixture was kept warm for 2 hours, and the temperature was raised to 270°C for reaction for 6 hours, 22 parts of higher fatty acids (myristic acid and lauroleic acid in a mass ratio of 3.6:1) were added for reaction for 6 hours, and the resin was obtained by cooling.

[0086] Example 3

[0087] The method for preparing indefinite island high-resilience ultrafine fiber polyurethane synthetic leather comprises the following steps:

[0088] S1. Preparation of indefinite island high resilience ultrafine fibers:

[0089] 50 parts of PA6, 0.5 parts of barium sulfate and 1.5 parts of calcined clay were ground and mixed with water, dried and added to a twin-screw machine for melt blending. LDPE (density 0.930 g / cm2) was added according to a mass ratio of 50:50 between the sea phase and the island phase. 3 ), melt blending and spinning to obtain indefinite island high resilience ultrafine fibers; the melt spinning conditions are: twin screw machine temperature 230-265°C, spinning speed spinning speed is 1200m / min, drafting multiple is 4 times, and drafting temperature is 90°C.

[0090] S2. Nonwoven fabric made by needle punching:

[0091] The indefinite island high resilience microfiber is made into non-woven fabric by needle punching, and the thickness of the non-woven fabric is 1.6mm;

[0092] S3, DMF solution for impregnation of polyurethane:

[0093] The nonwoven fabric was immersed in a polyurethane DMF solution (the mass fraction of polyurethane was 35%), then placed in a DMF aqueous solution (the mass fraction of DMF was 16%) for coagulation, and then washed with water;

[0094] S4, toluene extraction reduction:

[0095] The non-woven fabric is extracted and reduced with a toluene solution at a temperature of 90°C to produce a synthetic leather semi-finished product;

[0096] S5. Coating polyurethane slurry:

[0097] The synthetic leather semi-finished product is heat-treated, first at 70°C for 20 minutes, then heated to 110°C for 5 minutes; then coated with polyurethane slurry with a thickness of 1.4 mm; the polyurethane slurry is prepared by mixing 100 parts of polyurethane resin, 20 parts of higher fatty acid rosin ester resin, 5 parts of sodium diisooctyl sulfosuccinate, 5 parts of color paste, 3 parts of polyvinyl pyrrolidone, and 80 parts of DMF;

[0098] S6, finishing:

[0099] The synthetic leather coated with polyurethane slurry is finally finished to obtain indefinite island high resilience superfine fiber polyurethane synthetic leather.

[0100] In this embodiment, the higher fatty acid rosin ester resin is prepared by the following method:

[0101] 100 parts of polymerized rosin were crushed and melted at 240°C, 2 parts of calcium sulfite were added, and then 12.7 parts of pentaerythritol and 1.5 parts of xylitol were added, and the mixture was kept warm for 2 hours, and the temperature was raised to 250°C for reaction for 6 hours, 25 parts of higher fatty acids (myristic acid and lauroleic acid in a mass ratio of 4:1) were added for reaction for 6 hours, and the resin was obtained after cooling.

[0102] Comparative Example 1

[0103] The difference between this comparative example and Example 2 is that the ratio of the island phase material in the indefinite island high resilience ultrafine fiber is different. The island phase material in the indefinite island high resilience ultrafine fiber in this comparative example comprises 50 parts of PA6, 0.2 parts of barium sulfate and 0.8 parts of calcined clay.

[0104] Comparative Example 2

[0105] The difference between this comparative example and Example 2 is that the ratio of the island phase material in the indefinite island high resilience ultrafine fiber is different. The island phase material in the indefinite island high resilience ultrafine fiber in this comparative example comprises 50 parts of PA6, 0.7 parts of barium sulfate and 2 parts of calcined clay.

[0106] Comparative Example 3

[0107] The difference between this comparative example and Example 2 is that the components of the island phase in the indefinite-island high-resilience ultrafine fibers are different, and barium sulfate is not added to the island phase material in the indefinite-island high-resilience ultrafine fibers in this comparative example.

[0108] Comparative Example 4

[0109] The difference between this comparative example and Example 2 is that the island phase components in the indefinite-island high-resilience ultrafine fibers are different, and no calcined clay is added to the island phase material of the indefinite-island high-resilience ultrafine fibers in this comparative example.

[0110] Comparative Example 5

[0111] The difference between this comparative example and Example 2 is that the components of the island phase in the indefinite-island high-resilience ultrafine fibers are different, and the island phase material in the indefinite-island high-resilience ultrafine fibers in this comparative example is only PA6.

[0112] Comparative Example 6

[0113] The difference between this comparative example and Example 2 is that the synthetic leather semi-finished product in this comparative example is not heat-treated before being coated with the polyurethane slurry.

[0114] Comparative Example 7

[0115] The difference between this comparative example and Example 2 is that the heat treatment conditions before the synthetic leather semi-finished product is coated with the polyurethane slurry are different. The heat treatment condition in this comparative example is to keep warm at 100° C. for 3 minutes.

[0116] Comparative Example 8

[0117] The difference between this comparative example and Example 2 is that the components of the polyurethane slurry are different, and the higher fatty acid rosin ester resin in the polyurethane slurry of this comparative example is replaced by polyurethane resin.

[0118] Comparative Example 9

[0119] The difference between this comparative example and Example 2 is that the higher fatty acid rosin ester resin in the polyurethane slurry of this comparative example is replaced by polymerized rosin.

[0120] Comparative Example 10

[0121] The difference between this comparative example and Example 2 is that in the preparation process of the higher fatty acid rosin ester resin in the polyurethane slurry of this comparative example, the higher fatty acid is myristic acid and lauroleic acid in a mass ratio of 2.5:1.

[0122] Comparative Example 11

[0123] The difference between this comparative example and Example 2 is that in the preparation process of the higher fatty acid rosin ester resin in the polyurethane slurry of this comparative example, the higher fatty acid is myristic acid and lauroleic acid in a mass ratio of 4.5:1.

[0124] Test Example 1

[0125] Performance of indefinite island high resilience microfiber

[0126] The indefinite island high resilience ultrafine fibers obtained in Examples 1-3 and Comparative Examples 1-5 were used as samples, and their mechanical properties were tested with reference to GB / T14337-2008. The results are shown in Table 1.

[0127] Table 1. Properties of indefinite island high resilience microfiber

[0128]

[0129] As shown in the data of Table 1, the present invention uses PA6 mixed with barium sulfate and calcined clay as the island phase to prepare the indefinite island high resilience superfine fiber. By optimizing the amount of barium sulfate and calcined clay, the defects of the insufficient mechanical properties of the traditional indefinite island PA6 sea island fiber can be improved. The breaking strength of the indefinite island high resilience superfine fiber reaches 4.22-4.48cN / dtex, the breaking elongation is greater than 160%, and the mechanical properties are excellent. The breaking strength and breaking elongation of the indefinite island high resilience superfine fiber obtained in Comparative Example 5 are both much different from those in Example 2, and are lower than those in Comparative Examples 1-4. The breaking strength and breaking elongation of the indefinite island high resilience superfine fiber obtained in Comparative Examples 1-4 are also lower than those in Example 2. It can be seen that barium sulfate and calcined clay are added to the island phase PA6 at the same time, and the amount of barium sulfate and calcined clay is controlled within the scope of the present invention, so that the obtained indefinite island high resilience superfine fiber can simultaneously obtain excellent breaking strength and breaking elongation.

[0130] Test Example 2

[0131] Properties of indefinite island high resilience microfiber polyurethane synthetic leather

[0132] The indefinite island high resilience microfiber polyurethane synthetic leather obtained in Examples 1-3 and Comparative Examples 1-11 was used as a sample, and its tensile properties and peel strength were tested with reference to the standard GB / T8949-2008. The results are shown in Table 2. The synthetic leather obtained in Example 1 and Comparative Examples 1-11 was recorded as AL, and its expansion and contraction rate after being placed at 150°C for 5 minutes was tested. The results are shown in Table 2. Figure 3 shown.

[0133] Table 2. Properties of indefinite island high resilience microfiber polyurethane synthetic leather

[0134]

[0135]

[0136] As shown in Table 2 and Figure 3As shown in the data, the indefinite island high-resilience ultrafine fiber polyurethane synthetic leather obtained by the present invention has excellent mechanical properties, high peel strength and excellent heat resistance. The mechanical properties of the synthetic leather obtained in Comparative Examples 1-5 are significantly different from those in Example 2, and the heat resistance of Comparative Examples 3-5 is also slightly reduced, indicating that the preparation of indefinite island high-resilience ultrafine fibers with PA6 mixed with barium sulfate and calcined clay as island phases is helpful to improve the mechanical properties and heat resistance of the fibers, thereby improving the performance of synthetic leather. The peel strength of the synthetic leather obtained in Comparative Examples 6 and 7 is significantly reduced. It can be seen that the semi-finished synthetic leather is heat-treated before coating with polyurethane slurry, which helps to promote the penetration of polyurethane slurry on the surface of synthetic leather and improve the peel strength. The mechanical properties, high peel strength and heat resistance of the synthetic leather obtained in Comparative Examples 8-11 are all reduced compared with those in Example 2. It can be seen that the addition of higher fatty acid rosin ester resin to the polyurethane slurry, in coordination with other components, helps to improve the comprehensive performance of the product.

[0137] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An indefinite island ultrafine fiber polyurethane synthetic leather, prepared by using indefinite island fiber, characterized in that: The indefinite island fiber has LDPE as the sea phase and PA6 as the island phase; wherein the island phase also contains barium sulfate and calcined clay; the content of the barium sulfate is 0.6-1% of the mass of PA6, and the content of the calcined clay is 2-3% of the mass of PA6; the preparation method of the indefinite island ultrafine fiber polyurethane synthetic leather comprises the following steps: (1) The adventitious island fibers are made into non-woven fabrics by needle punching; (2) The non-woven fabric is immersed in a DMF solution of polyurethane, then placed in an aqueous DMF solution for coagulation and washed with water; (3) Extraction and reduction with toluene solution to produce synthetic leather semi-finished products; (4) Heat treatment of synthetic leather semi-finished products, the heat treatment process is: first keep the temperature at 60-70°C for 10-20 minutes, then heat it to 100-110°C and keep it for 3-5 minutes, and then coat the surface with polyurethane slurry, the polyurethane slurry contains: 100 parts of polyurethane resin, 10-20 parts of higher fatty acid rosin ester resin, 2-5 parts of penetrant, 5-10 parts of color paste, 1-3 parts of polyvinyl pyrrolidone, 50-80 parts of DMF; (5) Finally, the indefinite island ultrafine fiber polyurethane synthetic leather is obtained through post-finishing; Wherein, the higher fatty acid rosin ester resin is prepared by the following method: The polymerized rosin is crushed, melted at 220-240°C, a catalyst is added, and then a polyol is added, the temperature is kept, and the temperature is increased for reaction for 3-6 hours, and then a higher fatty acid is added to continue the reaction for 4-7 hours, and the resin is obtained by cooling; the polyol is pentaerythritol and xylitol, and the addition amounts of pentaerythritol and xylitol are 10-12.7% and 1.5-2% of the mass of the polymerized rosin respectively; the higher fatty acid is myristic acid and lauroleic acid in a mass ratio of 3-4:1; the addition amount of the higher fatty acid is 18-25% of the mass of the polymerized rosin.

2. The indefinite island ultrafine fiber polyurethane synthetic leather according to claim 1, characterized in that: The content of barium sulfate is 0.8% of the mass of PA6, and the content of calcined clay is 2.6% of the mass of PA6.

3. The indefinite island ultrafine fiber polyurethane synthetic leather according to claim 1 or 2, characterized in that: The following steps are also included: Barium sulfate, calcined clay and PA6 are ground and mixed with water, dried, added to a twin-screw machine for melt blending, LDPE is added, and melt blending and spinning are performed to obtain indefinite island fibers.

Images