Laser-free weakening PU composite leather and preparation method thereof

Abstract

The present invention discloses a laser-weakening-free PU composite leather, comprising a base fabric and a composite layer coated on the base fabric; the base fabric is made of L-polylactic acid and sprayed with a mixed liquid; the components of the mixed liquid are calculated by weight as follows: 70-80 parts of physiological saline; 10-15 parts of acrylic resin; and 5-10 parts of a thickener. The present invention also provides a method for preparing the laser-weakening-free PU composite leather, comprising preparing release paper, fabricating a surface layer, fabricating an adhesive layer, bonding and laminating the base fabric, peeling the release paper, performing an aging treatment, and fabricating the surface treatment layer. The present invention simplifies the process, avoids the use of a laser weakening process, and reduces costs.

Description

Technical Field

[0001] The invention relates to the field of PU composite leather, and in particular to a PU composite leather free of laser weakening and a preparation method thereof. Background Art

[0002] The current technical solution is to use laser weakening technology to add a high-solid layer to the PU coating. After drying, the high-solid layer has good film-forming properties and has very dense foaming pores. When the laser burns the back of the PU, the sensor can sense the laser burning the PU through the dense foaming pores and stop burning, thereby completing the laser weakening. The weakened PU composite leather has no traces or any abnormalities on the leather surface, but the process is cumbersome, complex and difficult to control, and the cost is relatively high. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the present invention provides a PU composite leather that does not require laser weakening and a preparation method thereof. The PU composite leather and its preparation method do not require the use of laser weakening technology, which simplifies the process operation difficulty. At the same time, the PU composite leather can be applied to the airbag and can be completely exploded from the exact position.

[0004] The present invention is achieved through the following technical solutions:

[0005] A laser-weakening-free PU composite leather comprising a base fabric and a composite layer coated on the base fabric;

[0006] The base fabric is made of L-polylactic acid and is sprayed with a mixed liquid;

[0007] The components of the mixed liquid are calculated in parts by weight as follows: physiological saline: 70-80 parts, acrylic resin: 10-15 parts, and thickener: 5-10 parts.

[0008] Furthermore, the thickener is sodium polyacrylate.

[0009] Furthermore, the base fabric has a thickness of 0.45 mm.

[0010] Furthermore, the composite layer includes a surface treatment layer, a surface layer and an adhesive layer, the surface layer is arranged between the surface treatment layer and the adhesive layer, and the adhesive layer is also connected to the base fabric.

[0011] Furthermore, the surface layer and the adhesive layer are both made of solvent-free polyurethane, which accounts for 100 parts by weight.

[0012] Furthermore, the surface treatment layer is solvent-free polyurethane, which accounts for 100 parts by weight.

[0013] The present invention also provides a method for preparing laser-weakening-free PU composite leather, which comprises the following steps:

[0014] Step S1: Release paper preparation: Select appropriate release paper and assemble it on the unwinder of the linkage coating machine;

[0015] Step S2: preparing a surface layer: preparing a surface layer solution, applying the surface layer solution on the release paper of step S1, and drying and forming the surface layer;

[0016] Step S3: preparing a glue layer solution, applying the glue layer solution on the surface layer of step S2, and drying and forming the glue layer;

[0017] Step S4: bonding and laminating the base fabric: bonding and laminating the adhesive layer in step S3 to the front side of the base fabric and drying the adhesive layer, and then spraying the mixed liquid on the back side of the base fabric to form a PU base with paper;

[0018] Step S5: Peeling off the release paper: Peeling off the paper-coated PU base formed in step S4 from the release paper to obtain a PU semi-finished product;

[0019] Step S6: Curing treatment: placing the PU semi-finished product obtained in step S5 in an oven for curing and cooling to obtain a cured PU composite leather;

[0020] Step S7: Surface treatment layer preparation: Prepare a surface treatment layer solution, apply the surface treatment layer solution to the PU composite leather matured in step S6, and dry it to form the PU composite leather, thereby preventing laser weakening.

[0021] Furthermore, the step S4 specifically includes: bonding the adhesive layer of step S3 to the front side of the base fabric and drying and forming it, then spraying a mixed liquid prepared by 70 to 80 parts of physiological saline, 10 to 15 parts of acrylic resin, and 5 to 10 parts of thickener on the back side of the base fabric and drying and forming it to form a PU base blank with paper.

[0022] Furthermore, the preparation of the mixed liquid specifically includes: adding 70-80 parts of physiological saline, 10-15 parts of acrylic resin, and 5-10 parts of sodium polyacrylate into a liquid mixing tank in sequence, and stirring at a stirring speed of 390-410 rpm for 15-25 minutes. After stirring evenly, measuring the viscosity of the solution, and then putting it into production.

[0023] Furthermore, the viscosity of the solution is controlled at 1800-2000 cps.

[0024] Furthermore, after the mixed liquid is sprayed on the back of the base fabric, the drying temperature is 125-135° C. and the drying time is 2.5-3.5 minutes.

[0025] Furthermore, the spraying amount of the mixed liquid is 150-180 g / m², and the spraying speed is 12 m / min.

[0026] Furthermore, the drying temperature for bonding the base fabric is 95° C. to 105° C., and the drying time is 3.5 to 4.5 minutes.

[0027] Furthermore, the bonding pressure of the base fabric is 1.5 to 2.5 kg.

[0028] Furthermore, the coating amount of the surface layer is 37 g / m² to 43 g / m², and the coating speed is 9 m / min to 11 m / min.

[0029] Furthermore, the coating amount of the adhesive layer is 190g / m² to 210g / m², and the coating speed is 9m / min to 11m / min.

[0030] Furthermore, the coating amount of the surface treatment layer is 33 to 38 g / m², and the coating speed is 10 to 12 m / min.

[0031] Furthermore, the surface layer is dried at a temperature of 125 to 135° C. and for a time of 3.5 to 4.5 minutes.

[0032] Furthermore, the aging temperature in step S6 is 140° C. and the aging time is 8 minutes.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] 1. The present invention simplifies the process operation difficulty by eliminating the laser weakening technology. In the PU composite leather-covered airbag explosion area, the airbag is exploded from the accurate position without any abnormal appearance.

[0035] 2. The present invention sprays a mixed liquid on the back of the base fabric, and the mixed liquid uses physiological saline, acrylic resin and thickener. The reagents used in the formula have low toxicity, which reduces pollution to the environment and reduces harm to the human body.

[0036] 3. The weaving material of the base fabric of the present invention is made of L-polylactic acid, which is relatively easy to degrade, non-toxic, non-irritating, high in strength, good in plasticity, and easy to process and shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic structural diagram of a laser-weakening-free PU composite leather according to an embodiment of the present invention;

[0038] Figure 2 This is the explosion diagram of the PU composite leather prepared in Example 3 applied to an airbag;

[0039] Figure 3 This is a diagram showing the explosion of the PU composite leather prepared in Comparative Example 1-1 when applied to an airbag;

[0040] 1. Base fabric; 2. Adhesive layer; 3. Surface layer; 4. Surface treatment layer; 5. Composite layer. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment, so that those skilled in the art can fully understand the technical contents of the present invention. It should be understood that the following examples are used to further illustrate the present invention and cannot be interpreted as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present invention all belong to the scope of protection of the present invention. The specific preparation method parameters of the following examples are also only an example in a suitable range, that is, those skilled in the art can make a selection within a suitable range according to the description herein, and are not limited to the specific numerical values ​​exemplified below.

[0042] like Figure 1 As shown, a PU composite leather that does not require laser weakening includes a base fabric 1 and a composite layer 5 coated on the base fabric 1.

[0043] The composite layer 5 includes a surface treatment layer 4, a surface layer 3 and an adhesive layer 2. The surface layer 3 is arranged between the surface treatment layer 4 and the adhesive layer 2. The adhesive layer 2 is connected to the base fabric 1.

[0044] The base fabric 1 is made of L-polylactic acid and is sprayed with a mixed liquid;

[0045] The components of the mixed liquid are calculated by weight as follows:

[0046] Physiological saline: 70-80 parts, acrylic resin: 10-15 parts, thickener: 5-10 parts.

[0047] Furthermore, the thickness of the base fabric 1 is 0.45 mm.

[0048] Furthermore, the thickener is sodium polyacrylate.

[0049] Furthermore, the surface layer 3 and the adhesive layer 2 are both made of solvent-free polyurethane, which accounts for 100 parts by weight.

[0050] Furthermore, the surface treatment layer 4 is solvent-free polyurethane, which accounts for 100 parts by weight.

[0051] The present invention also provides a method for preparing laser-weakening-free PU composite leather, which comprises the following steps:

[0052] Step S1: Release paper preparation: Select appropriate release paper and assemble it on the unwinder of the linkage coating machine;

[0053] Step S2: preparing the surface layer 3: preparing a surface layer solution, applying the surface layer solution on the release paper of step S1, and drying and forming the surface layer;

[0054] Step S3: preparing the adhesive layer 2: preparing an adhesive layer solution, applying the adhesive layer solution on the surface layer 3 of step S2, and drying and forming the adhesive layer;

[0055] Step S4: bonding and laminating the base fabric 1: bonding and laminating the adhesive layer 2 of step S3 to the front side of the base fabric 1 and drying and forming the adhesive layer, spraying a mixed liquid prepared by 70-80 parts of physiological saline, 10-15 parts of acrylic resin, and 5-10 parts of thickener onto the back side of the base fabric 1 and drying and forming the mixed liquid, thereby forming a PU base with paper;

[0056] Step S5: Peeling off the release paper: Peeling off the paper-coated PU base formed in step S4 from the release paper to obtain a PU semi-finished product;

[0057] Step S6: Curing treatment, placing the PU semi-finished product obtained in step S5 in an oven for curing and cooling to obtain a cured PU composite leather;

[0058] Step S7: Preparation of surface treatment layer 4: Prepare a surface treatment layer solution, apply the surface treatment layer solution to the PU composite leather matured in step S6, and dry and shape it to prevent the PU composite leather from being weakened by laser.

[0059] Furthermore, the preparation of the mixed liquid in step S4 specifically includes: adding 70-80 parts of physiological saline, 10-15 parts of acrylic resin, and 5-10 parts of sodium polyacrylate into a liquid mixing tank, stirring at a stirring speed of 390-410 rpm for 15-25 minutes, controlling the viscosity of the solution at 1800-2000 cps, and then putting it into production.

[0060] Furthermore, the spraying amount of the mixed liquid is 150-180 g / m², and the spraying speed is 12 m / min.

[0061] Furthermore, in step S4, the drying temperature after spraying the mixed liquid on the back of the base fabric 1 is 125-135° C., and the drying time is 2.5-3.5 minutes.

[0062] Furthermore, the drying temperature of the base fabric 1 after bonding and laminating is 95° C. to 105° C., and the drying time is 3.5 to 4.5 minutes.

[0063] Furthermore, the pressure of bonding the base fabric is 1.5 to 2.5 kg.

[0064] Furthermore, the coating amount of the surface layer 3 is 37 g / m² to 43 g / m², and the coating speed is 9 m / min to 11 m / min.

[0065] Furthermore, the coating amount of the adhesive layer 2 is 190 g / m² to 210 g / m², and the coating speed is 9 m / min to 11 m / min.

[0066] Furthermore, the coating amount of the surface treatment layer 4 is 33 to 38 g / m², and the coating speed is 10 to 12 m / min.

[0067] Furthermore, the surface layer 3 is dried at a temperature of 125 to 135° C. and for a time of 3.5 to 4.5 minutes.

[0068] Furthermore, in step S6, the aging temperature is 140° C. and the aging time is 8 minutes.

[0069] Furthermore, the adhesive layer 2 is dried at a temperature of 95° C. to 105° C., and for a drying time of 3.5 to 4.5 minutes.

[0070] Furthermore, the surface treatment layer 4 is dried at a temperature of 125 to 135° C. and for a time of 3.5 to 4.5 minutes.

[0071] The base fabric of the present invention is made of L-polylactic acid, which is relatively easy to degrade. L-polylactic acid has an asymmetric carbon atom in the lactic acid molecule and is optically active. Therefore, polylactic acid is also divided into D-polylactic acid (PDLA), L-polylactic acid (PLLA), racemic polylactic acid (PLLA), and optically inactive polylactic acid (Meso-PLA). PLA is an important biodegradable polymer material. It is non-toxic, non-irritating, biodegradable and absorbable, has high strength, good plasticity, and is easy to process and shape. The degradation period is 2 to 12 months.

[0072] The use of sodium polyacrylate as a thickener in the mixed liquid of the present invention exhibits a significant thickening effect, with viscosity increasing accordingly with increasing sodium polyacrylate dosage. Aqueous sodium polyacrylate solutions are large molecules with strong stringiness and high viscosity. When mixed with a hydrophilic sol as a protective colloid, they become a protective colloid for the hydrophilic sol, stabilizing the emulsion system. Sodium polyacrylate is a polymer that dissolves well in water, forming a true solution. Furthermore, sodium polyacrylate itself carries an electrical charge, which can promote the aggregation of suspended particles with different surface charges.

[0073] In order to further enhance the PU weakening performance and prevent the coating glue from penetrating into the gap between the PU layer and the base fabric, the present invention sprays a mixed liquid on the back of the PU and above the base fabric. This mixed liquid is mainly composed of physiological saline, which reduces environmental pollution. The process is simple and the cost is reduced. The development of laser-free weakened PU composite leather has opened up another path for airbag explosion, while bringing new orders to the company and creating additional profits.

[0074] The following embodiments are used to further illustrate and describe the concept of the present invention, but do not mean that the present invention is limited to the specific embodiments described below. In the embodiments, any specific numerical value within the scope of the present invention is applicable. Example

[0075] Step S1: Prepare the release paper, select appropriate release paper and assemble it on the unwinder;

[0076] Step S2: Surface layer 3 is prepared. Polyurethane is selected according to the material composition of surface layer 3 and coated on the release paper of step S1 according to the weight percentage calculated as 100%. The coating amount of surface layer 3 is 40g / m² and the coating speed is 10m / min. After coating, the surface layer 3 is dried at a temperature of 130°C for 4 minutes to obtain surface layer 3.

[0077] Step S3: preparing the adhesive layer 2. According to the material composition of the adhesive layer 2, polyurethane is selected and coated on the surface layer 3 of step S2 according to the weight percentage calculated as 100%. The coating amount of the adhesive layer 2 is 200g / m² and the coating speed is 10m / min. After the coating is completed, the adhesive layer 2 is dried at a temperature of 95°C to 105°C for 3.5 to 4.5 minutes to obtain the adhesive layer 2.

[0078] Step S4: Bonding the base fabric 1. The adhesive layer 2 from step S3 is bonded to the front surface of the base fabric 1 under a pressure of 1.5 kg and dried at 100° C. for 4 minutes to set the shape. A mixture of 70 parts physiological saline, 10 parts acrylic resin, and 5 parts thickener is then sprayed onto the back surface of the base fabric 1 made of L-polylactic acid. The mixture is then dried at 130° C. for 3 minutes to form a PU base with paper. The mixture is stirred at a speed of 390-410 rpm for 15-25 minutes, and the viscosity of the mixture is controlled at 1800 cps.

[0079] Step S5: Peeling off the release paper: Peeling off the paper-coated PU base formed in step S4 from the release paper to obtain a PU semi-finished product;

[0080] Step S6: Curing treatment: placing the PU semi-finished product obtained in step S5 in an oven at a temperature of 140° C. for 8 minutes to obtain a cured PU composite leather;

[0081] Step S7: Preparation of surface treatment layer 4: According to the material composition of surface treatment layer 4, polyurethane is selected and coated on the PU composite leather matured in step S6 according to the weight percentage calculated as 100% and then dried at a temperature of 125-135°C for 3.5-4.5 minutes to form the PU composite leather to avoid laser weakening.

[0082] Depend on Figure 2It can be seen that the PU composite leather prepared in Example 1 can be used in an airbag and explode normally. Example

[0083] Step S1: Prepare the release paper, select appropriate release paper and assemble it on the unwinder;

[0084] Step S2: Surface layer 3 is prepared. Polyurethane is selected according to the material composition of surface layer 3 and coated on the release paper of step S1 according to the weight percentage calculated as 100%. The coating amount of surface layer 3 is 40g / m² and the coating speed is 10m / min. After coating, the surface layer 3 is dried at a temperature of 130°C for 4 minutes to obtain surface layer 3.

[0085] Step S3: preparing the adhesive layer 2. According to the material composition of the adhesive layer 2, polyurethane is selected and coated on the surface layer 3 of step S2 according to the weight percentage calculated as 100%. The coating amount of the adhesive layer 2 is 200g / m² and the coating speed is 10m / min. After the coating is completed, the adhesive layer 2 is dried at a temperature of 95°C to 105°C for 3.5 to 4.5 minutes to obtain the adhesive layer 2.

[0086] Step S4: Bonding the base fabric 1. The adhesive layer 2 from step S3 is bonded to the front surface of the base fabric 1 under a pressure of 2 kg and dried at 95° C. for 4.5 minutes to set the shape. A mixture of 75 parts physiological saline, 13 parts acrylic resin, and 8 parts thickener is then sprayed onto the back surface of the base fabric 1 made of L-polylactic acid. The mixture is then dried at 125° C. for 3.5 minutes to set the shape, forming a PU base with paper. The mixture is stirred at a speed of 390-410 rpm for 15-25 minutes to achieve uniformity. The viscosity of the mixture is controlled at 1900 cps.

[0087] Step S5: Peeling off the release paper: Peeling off the paper-coated PU base formed in step S4 from the release paper to obtain a PU semi-finished product;

[0088] Step S6: Curing treatment: placing the PU semi-finished product obtained in step S5 in an oven at a temperature of 140° C. for 8 minutes to obtain a cured PU composite leather;

[0089] Step S7: Preparation of surface treatment layer 4: According to the material composition of surface treatment layer 4, polyurethane is selected and coated on the PU composite leather matured in step S6 according to the weight percentage calculated as 100% and then dried at a temperature of 125-135°C for 3.5-4.5 minutes to form the PU composite leather to avoid laser weakening.

[0090] The PU composite leather prepared in Example 2 can be used on an airbag and explode normally. Example

[0091] Step S1: Prepare the release paper, select appropriate release paper and assemble it on the unwinder;

[0092] Step S2: Surface layer 3 is prepared. Polyurethane is selected according to the material composition of surface layer 3 and coated on the release paper of step S1 according to the weight percentage calculated as 100%. The coating amount of surface layer 3 is 40g / m² and the coating speed is 10m / min. After coating, the surface layer 3 is dried at a temperature of 130°C for 4 minutes to obtain surface layer 3.

[0093] Step S3: preparing the adhesive layer 2. According to the material composition of the adhesive layer 2, polyurethane is selected and coated on the surface layer 3 of step S2 according to the weight percentage calculated as 100%. The coating amount of the adhesive layer 2 is 200g / m² and the coating speed is 10m / min. After the coating is completed, the adhesive layer 2 is dried at a temperature of 95°C to 105°C for 3.5 to 4.5 minutes to obtain the adhesive layer 2.

[0094] Step S4: Bonding and laminating the base fabric 1. The adhesive layer 2 of step S3 is bonded to the front surface of the base fabric 1 under a pressure of 2 kg and dried at 105° C. for 3.5 minutes to set the shape. Then, a mixed liquid prepared by spraying 80 parts of physiological saline, 15 parts of acrylic resin, and 10 parts of thickener is sprayed on the back surface of the base fabric 1 made of L-polylactic acid. The mixed liquid is dried at 135° C. for 2.5 minutes to set the shape to form a PU base with paper. The mixed liquid is stirred at a speed of 390-410 rpm for 15-25 minutes to be uniformly stirred. The viscosity of the mixed liquid is controlled at 2000 cps.

[0095] Step S5: Peeling off the release paper: Peeling off the paper-coated PU base formed in step S4 from the release paper to obtain a PU semi-finished product;

[0096] Step S6: Curing treatment: placing the PU semi-finished product obtained in step S5 in an oven at a temperature of 140° C. for 8 minutes to obtain a cured PU composite leather;

[0097] Step S7: Preparation of surface treatment layer 4: According to the material composition of surface treatment layer 4, polyurethane is selected and coated on the PU composite leather matured in step S6 according to the weight percentage calculated as 100% and then dried at a temperature of 125-135°C for 3.5-4.5 minutes to form the PU composite leather to avoid laser weakening.

[0098] The PU composite leather prepared in Example 3 can be normally exploded when applied to an airbag.

[0099] Comparative Example 1-1

[0100] Compared with Example 1, only the mixed liquid was not sprayed on the back of the base fabric 1, and the other parameters were the same. Figure 3 It can be seen that the PU composite leather prepared by not spraying the mixed liquid on the base fabric 1 cannot achieve complete explosion when applied to the airbag.

[0101] It should be noted that the above preferred embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit and essence of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A PU composite leather free of laser weakening, characterized in that: It comprises a base fabric (1), and a composite layer (5) coated on the base fabric (1); The composite layer (5) comprises a surface treatment layer (4), a surface layer (3) and an adhesive layer (2), wherein the surface layer (3) is arranged between the surface treatment layer (4) and the adhesive layer (2); The base fabric (1) is made of L-polylactic acid, the adhesive layer (2) is also connected to the front side of the base fabric (1), and the back side of the base fabric (1) is sprayed with a mixed liquid; The components of the mixed liquid are calculated by weight as follows: Physiological saline: 70-80 parts, acrylic resin: 10-15 parts, thickener: 5-10 parts; The thickener is sodium polyacrylate.

2. The laser-weakening-free PU composite leather according to claim 1, characterized in that: The base fabric has a thickness of 0.45 mm.

3. The method for preparing laser-weakening-free PU composite leather according to any one of claims 1 to 2, characterized in that: The method comprises the following steps: Step S1: Release paper preparation: Select appropriate release paper and assemble it on the unwinder of the linkage coating machine; Step S2: Preparation of the surface layer (3): preparing a surface layer solution, coating the surface layer solution on the release paper of step S1, and drying and forming the surface layer; Step S3: Preparation of the adhesive layer (2): preparing an adhesive layer solution, applying the adhesive layer solution on the surface layer (3) of step S2, and drying and forming the adhesive layer; Step S4: bonding and laminating the base fabric (1): bonding and laminating the adhesive layer (2) of step S3 to the front side of the base fabric (1) and drying the adhesive layer, and then spraying the mixed liquid on the back side of the base fabric (1) to form a PU base with paper; Step S5: Peeling off the release paper: Peeling off the paper-coated PU base formed in step S4 from the release paper to obtain a PU semi-finished product; Step S6: Curing treatment: placing the PU semi-finished product obtained in step S5 in an oven for curing and cooling to obtain a cured PU composite leather; Step S7: Preparation of surface treatment layer (4): preparing a surface treatment layer solution, applying the surface treatment layer solution to the PU composite leather matured in step S6, and drying and forming the surface treatment layer solution to obtain a laser-free weakening PU composite leather.

4. The method for preparing laser-free PU composite leather according to claim 3, characterized in that: The step S4 specifically comprises: bonding the adhesive layer (2) of step S3 to the front side of the base fabric (1) and drying and forming the adhesive layer (2), and then spraying a mixed liquid prepared by 70-80 parts of physiological saline, 10-15 parts of acrylic resin, and 5-10 parts of thickener on the back side of the base fabric (1) and drying and forming the mixed liquid, thereby forming a PU base with paper.

5. The method for preparing laser-weakening-free PU composite leather according to claim 4, characterized in that: The preparation of the mixed liquid specifically includes: adding 70-80 parts of physiological saline, 10-15 parts of acrylic resin, and 5-10 parts of sodium polyacrylate in a liquid mixing tank in sequence, and stirring at a stirring speed of 390-410 rpm for 15-25 minutes. After stirring evenly, the viscosity of the solution is controlled at 1800-2000 cps before putting it into production.

6. The method for preparing laser-weakening-free PU composite leather according to claim 4, characterized in that: The drying temperature after spraying the mixed liquid on the back of the base fabric (1) is 125-135° C., and the drying time is 2.5-3.5 minutes.

7. The method for preparing laser-weakening-free PU composite leather according to claim 4, characterized in that: The spraying amount of the mixed liquid is 150-180 g / m², and the spraying speed is 12 m / min.

8. The method for preparing laser-weakening-free PU composite leather according to claim 4, characterized in that: The bonding pressure of the base fabric (1) is 1.5 to 2.5 kg.

Images