Preparation method of special texture synthetic leather with similar microsphere nest structure

Abstract

The invention discloses a preparation method of special texture synthetic leather with a similar microsphere nest structure. The preparation method comprises the following steps: step 1, preparing a wet process Base; 2, preparing a surface layer by a dry method; 3, preparing a middle layer by a dry method; and 4, preparing a bottom layer by a dry method. Semi-polyether semi-polyester resin is selected, and the bidirectional diffusion (double diffusion) rate between a solvent (DMF) and a coagulator (water) is controlled by controlling and regulating the flow speed and the flow state of a coagulating bath water solution, so that a spherical nest type pore layer structure is constructed. CaCO3 and cellulose are used as bubble hole supporting bodies, and a better absorbable grain layer is created.

Description

Technical Field

[0001] This invention belongs to the field of synthetic leather technology, and specifically relates to a method for preparing a special textured synthetic leather with a microsphere-like nest structure. Background Technology

[0002] Conventional absorbent synthetic leather is limited by the base fabric's texture, restricting the range of absorbent products. During production, the base fabric requires more paste, resulting in more volatile organic compounds remaining, which is detrimental to consumer health and the environment. Therefore, modifying the base fabric bonding interface can significantly improve the absorbent properties of the product. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a method for preparing a special textured synthetic leather with a micro-spherical nest structure, which controls the pore structure of the wet-processed skin layer, transforming it from the traditional dense type to a spherical nest-type pore layer structure, thereby enhancing the texturing properties and improving the suitability of the substrate.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a method for preparing a special textured synthetic leather with a microsphere-like nest structure, comprising the following steps:

[0006] Step 1, Preparation of wet-process Base, the specific steps are as follows:

[0007] Step 11, impregnation of base fabric: Fully unfold the base fabric and immerse it completely in an aqueous solution containing 40% DMF. After the base fabric is fully wetted, use a rolling mill to roll out the excess impregnation solution.

[0008] Step 12, Humidification: The impregnated base fabric is passed through a humidification device to control the humidity at 70%-80%;

[0009] Step 13, Coating: Apply a wet slurry to the conditioned base fabric;

[0010] Step 14, Coagulation: The base fabric coated with the wet slurry is placed into the coagulation device to stably bond the wet slurry with the base fabric and form bubbles, thus obtaining a wet base semi-finished product.

[0011] Step 15, Water washing: The solidified wet-process Base semi-finished product is washed with water to remove residue;

[0012] Step 16, Pre-drying: Pre-dry the washed wet-process Base semi-finished product to remove some of the moisture;

[0013] Step 17, Drying: After pre-drying, the wet-process Base semi-finished product is thoroughly dried to completely cure the coating material and form the wet-process Base;

[0014] Step 2: Dry surface layer preparation: The surface layer film material is prepared using a dry process;

[0015] Step 3: Dry intermediate layer preparation: An intermediate layer slurry is coated onto the surface layer membrane material using a dry process to prepare the semi-finished membrane material;

[0016] Step 4: Dry substrate preparation: The semi-finished film material is bonded to the wet substrate using a dry process.

[0017] In the above technical solution, in step 13, the wet slurry formulation by weight is as follows: 100 parts of semi-polyether semi-polyester resin, 18 parts of DL-semi-synthetic cellulose, 5 parts of CaCO3, 0.3 parts of defoamer, 140-150 parts of 28% DMF aqueous solution, and 0-10 parts of color paste.

[0018] In the above technical solution, in step 14, the coagulation liquid in the coagulation device is an aqueous solution of 28% dimethylformamide.

[0019] In the above technical solution, step 2, the preparation method of the dry surface layer is as follows: a surface layer slurry is prepared using water-based polyether resin, water-based color paste and additives, which is then coated onto release paper and dried to form a surface layer film.

[0020] In the above technical solution, step 3, the preparation method of the dry intermediate layer is as follows: an intermediate layer slurry is prepared using water-based polyether resin, water-based color paste and additives, and then coated onto the surface film material and dried to obtain a semi-finished film material.

[0021] In the above technical solution, step 4, the preparation method of the dry base layer is as follows: using water-based polyether resin and additives to prepare an adhesive layer slurry, scraping it onto the semi-finished film material, and bonding it to the wet base when it is in a semi-dry state.

[0022] The above technical solution also includes step 5: post-processing, including printing and texturing.

[0023] In the above technical solution, the specific method of printing is as follows: using polycarbonate printing resin and laser double-engraving rollers to print on the surface of the leather sample.

[0024] In the above technical solution, the specific method of texturing is as follows: the leather sample is first preheated at 150-180℃ to soften the surface of the leather sample, and then texturing is performed by a vacuum integrated texturing machine.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. A semi-polyether, semi-polyester resin is selected. By controlling the flow rate and flow state of the coagulation bath aqueous solution, the bidirectional diffusion rate between the solvent (DMF) and the coagulant (water) is controlled to construct a spherical, nested porous structure. CaCO3 and cellulose serve as the pore support, creating a better absorbent textured layer.

[0027] 2. Using a wet coating process, the interface state on the surface of the base fabric is modified, the micropores on the surface of the base fabric are sealed, the porosity of the base fabric is reduced, the density of the base fabric is enhanced, and the texturing effect of the vacuum integrated texturing machine is improved.

[0028] 3. The dry process uses water-based polyurethane with a three-layer structure to create an environmentally friendly textured surface. The overall material solvent content is ≤300ppm. Through an integrated textured processing technology, the leather-like style is enhanced. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the synthetic leather structure of the present invention;

[0030] Figure 2 This is a diagram of the wet-process spherical nest-type bubble structure of the present invention.

[0031] Among them, 1. Top layer; 2. Middle layer; 3. Bottom layer. Detailed Implementation

[0032] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below in conjunction with specific embodiments. This invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art. This invention will be defined only by the claims.

[0033] This invention provides a method for preparing a special textured synthetic leather with a microsphere-like nest structure, comprising the following steps:

[0034] 1. Preparation of wet-process Base

[0035] (1) Unwinding the base fabric: The base fabric is fully unwound by the unwinding device and given a certain tension to prepare for the subsequent impregnation process.

[0036] (2) Impregnation: The base fabric is completely immersed in an aqueous solution containing 40% DMF. After the base fabric is completely wetted, it is rolled on a rolling mill at a pressure of 5-6 kg / cm. 2 After fully impregnating the base fabric, the excess impregnating liquid is rolled out.

[0037] (3) Humidity conditioning: The impregnated base fabric is passed through a humidity conditioning device, and the temperature is controlled at 50℃-70℃ and the humidity is controlled at 70%-80%.

[0038] (4) Coating: The prepared wet slurry is coated onto the impregnated base fabric to obtain the wet base semi-finished product. The doctor blade height for coating is about 2.55-2.65 mm. The coating process requires two coatings to ensure that the wet slurry is completely and evenly coated onto the base fabric.

[0039] Table 1 Formulation of wet-process slurry

[0040]

[0041] Among them, the semi-polyether semi-polyester resin is selected: the resin with a polyether to polyester molar ratio of 40 / 60 is selected, and the soft segment is composed of polyoxypropylene glycol and polyadipate diol, which better constructs the cell structure of the wet-process muscle layer.

[0042] (5) Coagulation: The base fabric coated with wet slurry is placed into the coagulation device. The coagulation liquid is an aqueous solution of 28% DMF. The temperature of the coagulation device is 25℃-32℃, so that the wet slurry and the base fabric are stably bonded and corresponding bubbles are formed.

[0043] This invention controls the bidirectional diffusion rate between the solvent (DMF) and the coagulant (water) by regulating the flow rate and flow state of the coagulation bath aqueous solution, thereby constructing a spherical nested porous layer structure. CaCO3 and cellulose serve as the pore support, creating a better absorbent layer.

[0044] The flow state of the solution is changed by controlling the solvent content and temperature of the coagulation bath aqueous solution. The solvent (DMF) content of the coagulation bath aqueous solution is 25%-28%, and the temperature is controlled at 25-32℃, thereby changing the flow state of the solution.

[0045] The speed is controlled by adjusting the vehicle speed, which is kept between 12-13 m / min.

[0046] (6) Washing: The residual slurry, additives, etc. in the solidified wet-process Base semi-finished product are removed by the rolling mill equipment. The washing temperature is 40℃-60℃.

[0047] (7) Pre-drying: The wet-process Base semi-finished product after washing is pre-dried to remove some moisture, in preparation for subsequent complete drying. If pre-drying is not performed and the product is dried directly, problems such as: serious DMF residue, uneven distribution of wet slurry due to excessive humidity, affecting the muscle-forming effect of wet slurry, and affecting product properties may occur in the wet-process Base.

[0048] (8) Drying: After pre-drying treatment, the wet base semi-finished product is thoroughly dried to remove the DMF solvent and allow the coating material to fully solidify, forming the final form of wet base.

[0049] (9) Rewinding: The dried wet base is wound onto rollers by a rewinding device for use in the dry process.

[0050] 2. Dry Topcoat: Water-based polyether resin is used, and water-based pigments that match the resin are used in a certain proportion to give the topcoat a wider range of colors. The viscosity of the topcoat is controlled between 4000cps and 6000cps to facilitate the coating of the pigment onto the release paper. The pigment is applied to the release paper using a D-type squeegee, and then dried in a gradient of 75 / 85 / 95 / 125°C to form a complete topcoat film.

[0051] Among them, polyether resins use water as a carrier, with polypropylene glycol of molecular weight in the range of 2000 as the soft segment and aliphatic diisocyanate as the hard segment to form a full polyether surface layer, ensuring the wear resistance and texture absorption of the product surface.

[0052] 3. Dry intermediate layer: Water-based polyester resin is used, along with water-based colorant that matches the resin. The viscosity is controlled between 4500cps and 6500cps. A D-type knife is used to scrape the color paste onto the surface film. The color paste is dried in a gradient of 85 / 95 / 120 / 130 (unit: ℃) to bond the surface film and the intermediate film together.

[0053] Among them, polyester resin: a polyester diol with a molecular weight of 2400, obtained by adipic acid and ethylene glycol, is selected as the intermediate layer material to enhance the extensibility and physical properties of the membrane.

[0054] 4. Dry base layer: Water-based polyether resin, combined with crosslinking agent, leveling agent and defoamer, is used for base layer bonding. It is dried in a gradient oven at 110 / 115 / 120 / 120 / 120 / 130 / 130 (unit: °C) and then bonded to the wet base when the slurry is in a semi-dry state.

[0055] 5. Post-processing

[0056] (1) Printing process:

[0057] The leather sample surface is printed using polycarbonate printing resin and a laser double-coated roller. This process ensures the surface condition of the product during texturing and reduces problems such as surface material peeling off, clogging of texturing holes, and loss of patterns.

[0058] Among them, polycarbonate printing resin: polycarbonate resin material is selected as the printing material to ensure the surface condition of the product when the print is applied, and to reduce problems such as sticking to the roller and surface damage.

[0059] (2) Texture removal treatment:

[0060] The leather sample is first preheated to 150-180℃ to soften the surface, and then subjected to vacuum texturing treatment using an integrated vacuum texturing machine at a speed of 10-12m / min.

[0061] This invention relates to a synthetic leather comprising a top layer, a middle layer, and a bottom layer. The top layer uses a water-based polyether resin to provide better abrasion resistance and texture absorption. The middle layer uses a water-based polyester resin to improve the overall extensibility of the film, which is more conducive to the texture absorption effect of large patterns. The bottom layer uses a polyether resin to provide pattern stability, making the pattern more stable after texturing and preventing the pattern from flattening or losing its three-dimensionality due to ambient temperature.

[0062] This invention employs a wet coating process, forming a wet PU layer. The wet PU layer seals the interface with the base fabric, thereby modifying the interface state on the base fabric surface and sealing the micropores, reducing porosity. By controlling the water flow rate, the porosity of the wet layer is increased, altering the pore size and enabling a texture-absorbing process design. The structure of the wet-coated layer is modified, transforming the traditional dense structure into a spherical, nested pore structure, providing feasible conditions for the texture-absorbing process of the product.

[0063] The polyurethane uses water as a carrier, the soft segment is polyether polyol, the surface texture adopts a skin-like pattern, the overall material solvent content is ≤300ppm, and the leather-like style is enhanced through an integrated texturing process. Example 1

[0064] This embodiment provides a method for preparing a special textured synthetic leather with a microsphere-like nest structure, including the following steps:

[0065] 1. Preparation of wet-process Base

[0066] (1) Unwinding the base fabric: The base fabric is fully unwound by the unwinding device and given a certain tension to prepare for the subsequent impregnation process.

[0067] The base fabric is weft-knitted imitation cotton fleece, with a thickness of 1.0mm and a width of 145cm.

[0068] (2) Impregnation: The base fabric is completely immersed in an aqueous solution containing 40% DMF. After the base fabric is completely wetted, it is rolled on a rolling mill at a pressure of 6 kg / cm. 2 After fully impregnating the base fabric, the excess impregnating liquid is rolled out.

[0069] (3) Humidity conditioning: The impregnated base fabric is passed through a humidity conditioning device, and the temperature is controlled at 60℃ and the humidity is controlled at 80%.

[0070] (4) Coating: The prepared wet slurry is coated onto the impregnated base fabric to obtain the wet base semi-finished product. The doctor blade height for coating is about 2.55 mm. The coating process requires two coatings to ensure that the wet slurry is completely and evenly coated onto the base fabric.

[0071] Table 2 Formulation of wet-process slurry

[0072]

[0073] (5) Coagulation: The base fabric coated with wet slurry is placed into the coagulation device. The coagulation liquid is an aqueous solution of 28% DMF. The temperature of the coagulation device is 28℃, so that the wet slurry and the base fabric are stably bonded and corresponding bubbles are formed.

[0074] (6) Washing: The residual slurry, additives, etc. in the solidified wet-process Base semi-finished product are removed by the rolling mill equipment. The washing temperature is 40℃.

[0075] (7) Pre-drying: The wet-process Base semi-finished product after washing is pre-dried to remove some moisture, in preparation for subsequent complete drying. If pre-drying is not performed and the product is dried directly, problems such as: serious DMF residue, uneven distribution of wet slurry due to excessive humidity, affecting the muscle-forming effect of wet slurry, and affecting product properties may occur in the wet-process Base.

[0076] (8) Drying: After pre-drying treatment, the wet base semi-finished product is thoroughly dried to remove the DMF solvent and allow the coating material to fully solidify, forming the final form of wet base.

[0077] (9) Rewinding: The dried wet base is wound onto rollers by a rewinding device for use in the dry process.

[0078] 2. Dry Top Coat: Water-based polyether resin is used, and water-based pigments that match the resin are used in a certain proportion to give the top coat a wider range of colors. The viscosity of the top coat is controlled at 6000 cps to facilitate the coating of the pigment onto the release paper. The pigment is applied to the release paper using a D-type squeegee, and then dried in a gradient of 75 / 85 / 95 / 125 (unit: °C) to form a complete top coat film.

[0079] 3. Dry intermediate layer: Water-based polyester resin is used, along with water-based colorant that matches the resin. The viscosity is controlled at 5500cps. A D-type knife is used to scrape the color paste onto the surface film. The color paste is dried in a gradient of 85 / 95 / 120 / 130 (unit: ℃) to bond the surface film and intermediate film together.

[0080] 4. Dry base layer: Water-based polyether resin, combined with crosslinking agent, leveling agent and defoamer, is used for base layer bonding. It is dried in a gradient oven at 110 / 115 / 120 / 120 / 120 / 130 / 130 (unit: °C) and then bonded to the wet base when the slurry is in a semi-dry state.

[0081] 5. Post-processing

[0082] (1) Printing process:

[0083] The leather sample surface is printed using polycarbonate printing resin and a laser double-coated roller. This process ensures the surface condition of the product during texturing and reduces problems such as surface material peeling off, clogging of texturing holes, and loss of patterns.

[0084] (2) Texture removal treatment:

[0085] The leather sample is first preheated to 150℃ to soften its surface, and then subjected to vacuum texturing treatment using an integrated vacuum texturing machine at a speed of 12m / min.

[0086] Table 3 Dry Formulation

[0087]

[0088] Remark:

[0089]

[0090] Table 4 Printing Formula

[0091]

[0092] The synthetic leather prepared in Example 1 of this invention was tested for the following items, and the test results are as follows:

[0093] Table 5 Test Results

[0094]

[0095] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a special textured synthetic leather with a microsphere-like nest structure, characterized in that: Includes the following steps: Step 1, Preparation of wet-process Base, the specific steps are as follows: Step 11, impregnation of base fabric: Fully unfold the base fabric and immerse it completely in an aqueous solution containing 40% DMF. After the base fabric is fully wetted, use a rolling mill to roll out the excess impregnation solution. Step 12, Humidification: The impregnated base fabric is passed through a humidification device to control the humidity at 70%-80%; Step 13, Coating: Apply a wet slurry to the conditioned base fabric; Step 14, Coagulation: The base fabric coated with the wet slurry is placed into the coagulation device to stably bond the wet slurry with the base fabric and form bubbles, thus obtaining a wet base semi-finished product. Step 15, Water washing: The solidified wet-process Base semi-finished product is washed with water to remove residue; Step 16, Pre-drying: Pre-dry the washed wet-process Base semi-finished product to remove some of the moisture; Step 17, Drying: After pre-drying, the wet-process Base semi-finished product is thoroughly dried to completely cure the coating material and form the wet-process Base; Step 2: Dry surface layer preparation: The surface layer film material is prepared using a dry process; Step 3: Dry intermediate layer preparation: An intermediate layer slurry is coated onto the surface layer membrane material using a dry process to prepare the semi-finished membrane material; Step 4: Dry substrate preparation: The semi-finished film material is bonded to the wet substrate using a dry process.

2. The preparation method according to claim 1, characterized in that: In step 13, the wet slurry formulation, by weight, is as follows: 100 parts of semi-polyether semi-polyester resin, 18 parts of DL-semi-synthetic cellulose, 5 parts of CaCO3, 0.3 parts of defoamer, 140-150 parts of 28% DMF aqueous solution, and 0-10 parts of color paste.

3. The preparation method according to claim 1, characterized in that: In step 14, the coagulation liquid in the coagulation device is an aqueous solution of 28% dimethylformamide.

4. The preparation method according to claim 1, characterized in that: In step 2, the specific method for preparing the dry surface layer is as follows: a surface layer slurry is prepared using water-based polyether resin, water-based color paste, and additives, which is then coated onto release paper and dried to form the surface layer film.

5. The preparation method according to claim 1, characterized in that: In step 3, the dry intermediate layer is prepared by: using water-based polyether resin, water-based color paste and additives to prepare an intermediate layer slurry, coating it onto the surface film material, and drying it to obtain a semi-finished film material.

6. The preparation method according to claim 1, characterized in that: In step 4, the preparation method of the dry base layer is as follows: an adhesive layer slurry is prepared using water-based polyether resin and additives, and then coated onto the semi-finished film material and bonded to the wet base when it is in a semi-dry state.

7. The preparation method according to claim 1, characterized in that: It also includes step 5: post-processing, including printing and texturing.

8. The preparation method according to claim 7, characterized in that: The specific printing process is as follows: polycarbonate printing resin is used, and laser double-coated rollers are used to print on the surface of the leather sample.

9. The preparation method according to claim 7, characterized in that: The specific method for texturing is as follows: the leather sample is first preheated at 150-180℃ to soften the surface of the leather sample, and then texturing is performed by a vacuum integrated texturing machine.

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