PBS-based bionic texture bio-based leather 3D printing preparation method

Abstract

The invention relates to the technical field of leather preparation, in particular to a PBS-based bionic texture bio-based leather 3D printing preparation method, raw materials comprise the following components: poly (butylene succinate) (PBS), bio-based polyester polyol, bamboo fibers, a biodegradable elastomer (PCL elastomer) and bionic texture master batches; the components and the proportion are as follows: the proportion of the poly (butylene succinate) is 50 parts; the ratio of the bio-based polyester polyol is 20 parts; the proportion of the bamboo fibers is 15 parts; the proportion of the biodegradable elastomer is 10 parts; the proportion of the bionic texture master batch is 5 parts; comprising the following steps: 1, pretreating raw materials; 2, mixing the raw materials; step 3, a granulation process; 4, a 3D printing link; 5, a post-treatment stage; the invention aims to solve the problems that most existing biomimetic materials adopt non-degradable petroleum-based raw materials, pollution is easily caused after the biomimetic materials are discarded, the performance is unbalanced, and the material performance shows a remarkable binary opposite characteristic.

Description

Technical Field

[0001] The present invention relates to the technical field of leather preparation, and in particular to a PBS-based 3D printing preparation method for bio-based leather with biomimetic texture. Background Art

[0002] Bionic texture bio-based leather is a new type of environmentally friendly leather material developed based on bio-based materials and designed with surface texture based on bionic principles.

[0003] Existing bionic materials mostly use non-degradable petroleum-based raw materials, which are easy to cause pollution after disposal, and have unbalanced performance. The material properties show a significant binary opposition characteristic. Pure bio-based leather suddenly increases in brittleness due to excessive cross-linking of the hydrogen bond network. Although traditional synthetic leather has a certain degree of flexibility, it loses the touch of genuine leather due to the lack of the hierarchical structure of natural collagen fibers. At the same time, the production flexibility is low, the texture mostly relies on fixed molds, and the customization cost is high. Summary of the Invention

[0004] The purpose of the present invention is to provide a PBS-based 3D printing preparation method for bio-based leather with biomimetic textures, which solves the problems that existing biomimetic materials mostly use non-degradable petroleum-based raw materials, which are easy to cause pollution after disposal, and have unbalanced performance. The material properties show significant binary opposition characteristics. Pure bio-based leather suddenly increases in brittleness due to excessive cross-linking of the hydrogen bond network. Although traditional synthetic leather has a certain degree of flexibility, it loses the touch of genuine leather due to the lack of the hierarchical structure of natural collagen fibers. At the same time, the production flexibility is low, the texture mostly relies on fixed molds, and the customization cost is high.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a PBS-based bionic texture bio-based leather 3D printing preparation method, wherein the raw materials include the following components: polybutylene succinate (PBS), bio-based polyester polyol, bamboo fiber, biodegradable elastomer (PCL elastomer), and bionic texture masterbatch; the components and their proportions are as follows: the polybutylene succinate is 50 parts; the bio-based polyester polyol is 20 parts; the bamboo fiber is 15 parts; the biodegradable elastomer is 10 parts; and the bionic texture masterbatch is 5 parts; The following steps are also included: Step 1: Raw material pretreatment; Step 2: mixing raw materials; Step 3: Granulation process; Step 4: 3D printing; Step 5: Post-processing stage.

[0006] Preferably, the polybutylene succinate is passed through an 80-mesh sieve and placed in a vacuum drying oven, and dried at 70°C and a vacuum degree of -0.09 MPa for 10 hours; the bio-based polyester polyol is vacuum-evacuated at room temperature for 30 minutes and then placed in a 40°C oven for 2 hours; the bamboo fiber is cut into 3-5 mm short fibers, passed through a 40-mesh sieve to remove overlong or overshort fibers, and then added with 5% sodium hydroxide solution (liquid-solid ratio 10:1), placed in an 80°C autoclave and stirred for 2 hours, then washed with deionized water to a pH of 7, and finally placed in a 60°C forced air drying oven for 8 hours; the biodegradable elastomer is crushed into 1 cm×1 cm small pieces and preheated in a 50°C oven for 30 minutes; the bionic texture masterbatch is passed through a 100-mesh sieve and added to a high-speed mixer with 20% by mass of pretreated PBS particles, and mixed at 1500 r / min for 5 minutes.

[0007] Preferably, the raw materials are mixed mainly using a twin-screw mixer, the temperature of each zone is set, the screw speed is 100r / min, and after the temperature stabilizes, polybutylene succinate is first added; 1 minute after the polybutylene succinate is added, polyester polyol is slowly added from the side feeding port; 2 minutes after the polyester polyol is added, the crushed biodegradable elastomer is added; 3 minutes after the elastomer is added, bamboo fiber is added through the fiber-specific feeding port; 5 minutes after the bamboo fiber is added, the pre-dispersed masterbatch is added; the total mixing time is 20 minutes.

[0008] Preferably, after the mixed material is extruded from the twin-screw die, it immediately enters an underwater pelletizing system, and after pelletizing, it is dehydrated and dried with hot air to obtain blended particles with a moisture content of ≤0.5%.

[0009] Preferably, the blended particles are mixed with a photoinitiator (2 parts, such as TPO) and a reactive diluent (18 parts, such as trimethylolpropane triacrylate), stirred and dissolved at 60°C for 2 hours to form a uniform resin; a 3D model with a biomimetic texture is designed using CAD software and imported into a light-curing 3D printer; the printing parameters are: exposure time 3 seconds / layer, layer thickness 0.15 mm, platform rising speed 5 mm / min, and printing temperature 25°C.

[0010] Preferably, an ultrasonic cleaning machine is used to place the printed product in an ethanol solution (concentration 95%) and ultrasonically clean it for 10 minutes; the cleaned product is placed in a UV curing box under ultraviolet light (intensity 8mW / cm 2 ) for 15 minutes; then, using a flat-bed vulcanizer, the secondary-cured product is placed in a mold with a bionic texture cavity, and embossed at a set pressure and temperature to further directional aggregate the texture forming agent, deepening the texture depth from 5-10μm after printing to 20-30μm.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention takes a high proportion of bio-based degradable raw materials as the core. Through the proportioning and process design, it not only achieves the efficient degradation of materials in the natural environment, solving the pollution problem of traditional leather, but also uses the synergy of bamboo fiber reinforcement and flexible components to balance rigidity and flexibility. It combines 3D printing and physical embossing technology to form a realistic and durable bionic texture, combining environmental protection, mechanical properties and natural texture. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0013] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0014] The present invention provides a PBS-based bionic texture bio-based leather 3D printing preparation method, the raw materials include the following components: polybutylene succinate (PBS), bio-based polyester polyol, bamboo fiber, biodegradable elastomer (PCL elastomer), bionic texture masterbatch; the components and proportions are: polybutylene succinate is 50 parts; bio-based polyester polyol is 20 parts; bamboo fiber is 15 parts; biodegradable elastomer is 10 parts; and bionic texture masterbatch is 5 parts; The following steps are also included: Step 1: Raw material pretreatment; Step 2: mixing raw materials; Step 3: Granulation process; Step 4: 3D printing; Step 5: Post-processing stage; Polybutylene succinate has a molecular weight of 80,000-150,000 Da, a melting point of 110-120°C, a biodegradation rate (soil after 6 months) ≥ 60%, and a moisture content ≤ 0.1%. Polybutylene succinate is used as a matrix material to provide basic mechanical properties and biodegradability. Bio-based polyester polyols have a hydroxyl value of 25-35 mgKOH / g, an acid value ≤0.5 mgKOH / g, a bio-based content ≥90%, and a viscosity (25°C) of 500-800 mPa・s. Bio-based polyester polyols improve the flexibility of PBS and its compatibility with bio-based components, enhancing the overall elasticity of the material. Bamboo fiber has a length of 3-5mm, a diameter of 20-30μm, a cellulose content of ≥90%, a whiteness of ≥80%, and a moisture content of ≤8%. Bamboo fiber enhances the rigidity and tear resistance of materials, imparts a natural texture, and reduces costs. Biodegradable elastomers have a molecular weight of 50,000-80,000 Da, a glass transition temperature of -60 to -50°C, and an elongation at break of ≥400%. Biodegradable elastomers can improve the material's resilience and fatigue resistance, simulating the soft touch of natural leather. The carrier of bionic texture masterbatch is PBS (accounting for 60% of the masterbatch), the texture former is modified calcium carbonate microspheres (particle size 5-10μm, accounting for 30%), and the dispersant accounts for 10%. The bionic texture masterbatch provides the core component of the bionic texture. After the microspheres are oriented and arranged, a concave and convex texture structure similar to natural leather is formed.

[0015] After passing through an 80-mesh sieve, polybutylene succinate was placed in a vacuum drying oven and dried at 70°C and a vacuum degree of -0.09 MPa for 10 hours. The bio-based polyester polyol was vacuum-evacuated at room temperature for 30 minutes and then placed in a 40°C oven for 2 hours. The bamboo fiber was cut into 3-5 mm short fibers, passed through a 40-mesh sieve to remove overlong or overshort fibers, and then added with 5% sodium hydroxide solution (liquid-to-solid ratio of 10:1). The fibers were placed in an 80°C autoclave and stirred for 2 hours. The solution was then washed with deionized water to a pH of 7 and finally dried at 60°C with forced air for 8 hours. The biodegradable elastomer was crushed into 1 cm × 1 cm small pieces and preheated in a 50°C oven for 30 minutes. The biomimetic texture masterbatch was passed through a 100-mesh sieve and added to a high-speed mixer with 20% by mass of pretreated PBS particles and mixed at 1500 rpm for 5 minutes. The model of the vacuum drying oven is DZF-6050, which is used for drying PBS and bio-based polyester polyols. Drying is carried out at 70°C and a vacuum degree of -0.09MPa for 10 hours to remove moisture from the raw materials and control the moisture content to ≤0.1% to avoid bubbles or hydrolysis during processing. The state requirements after pretreatment are: moisture content ≤0.1% (tested by Karl Fischer titrator), and the particles have good fluidity and no agglomeration. The bio-based polyester polyol must have the following post-pretreatment requirements: no visible bubbles, and a stable viscosity (at 25°C) of 500-800 mPa·s (measured by a rotational viscometer). The model of the high-pressure reactor is GSHA-10, which is used for alkali treatment of bamboo fiber. The requirements for the state of bamboo fiber after pretreatment are: the fiber surface is rough and wax-free, the moisture content is ≤8%, and the whiteness is ≥80% (detected by a whiteness meter); Requirements for the state of biodegradable elastomer after pretreatment: maintain solid state, no adhesion, and easy to disperse; The model of the high-speed mixer is SHR-10A, which is used for pre-dispersion of bionic texture masterbatch. The state requirements after pretreatment are: the masterbatch and PBS are pre-mixed evenly, there are no agglomerates visible to the naked eye, and the dispersion degree of the texture former (calcium carbonate microspheres) is ≥90%.

[0016] The raw materials are mixed mainly using a twin-screw mixer. The temperature of each zone is set, and the screw speed is 100r / min. After the temperature stabilizes, polybutylene succinate is first added. One minute after the polybutylene succinate is added, polyester polyol is slowly added from the side feed port. Two minutes after the polyester polyol is added, the crushed biodegradable elastomer is added. Three minutes after the elastomer is added, bamboo fiber is added through the fiber-specific feed port. Five minutes after the bamboo fiber is added, the pre-dispersed masterbatch is added. The total mixing time is 20 minutes. The model of the twin-screw compounder is SHJ-36. The temperature of each zone is: 100℃ in zone 1, 120℃ in zone 2, 130℃ in zone 3 and 130℃ in zone 4. When the polybutylene succinate is melted and becomes viscous, add the polyester polyol. After adding, make sure that the materials are mixed evenly without stratification, then add the crushed biodegradable elastomer. When the materials are in a uniform melt state, add the bamboo fiber through the fiber-specific feeding port. After confirming that the fibers have no obvious agglomeration, add the pre-dispersed masterbatch. The total mixing time is 20 minutes to ensure that all materials are fully integrated. The alcohol ester is used as the matrix, which first melts to form a continuous phase, providing a dispersion carrier for subsequent components. The fluidity of polyester polyol is utilized to quickly mix with molten polybutylene succinate to improve the flexibility of the matrix. The elastomer is then dispersed in the molten matrix to further enhance the material's resilience and avoid high-temperature degradation caused by premature addition. The bamboo fiber is evenly dispersed in the melt, and the strong shear force of the twin-screw is used to open the fiber agglomerates and enhance the rigidity of the material. Finally, the masterbatch is evenly distributed in the melt, and the texture former (calcium carbonate microspheres) are directionally arranged with the shear force, laying the foundation for later texture forming.

[0017] After the mixed material is extruded from the twin-screw die, it immediately enters the underwater pelletizing system. After pelletizing, it is dehydrated and dried with hot air to obtain blended pellets with a moisture content of ≤0.5%; The underwater pelletizing system is SGL-80, with a cutter speed of 500-1500r / min, a cooling water temperature of 20-30°C, and a pellet diameter of 3-5mm. The mixed molten material is cut into uniform pellets. After pelletizing, it is dehydrated and hot-air dried (60°C, 30 minutes) to obtain blended pellets with a moisture content of ≤0.5%, which facilitates the subsequent raw material transportation and melt stability for 3D printing.

[0018] The blended particles were mixed with a photoinitiator (2 parts, such as TPO) and a reactive diluent (18 parts, such as trimethylolpropane triacrylate) and dissolved with stirring at 60°C for 2 hours to form a uniform resin. A 3D model with a biomimetic texture was designed using CAD software and imported into a light-curing 3D printer. The printing parameters were: exposure time 3 seconds / layer, layer thickness 0.15mm, platform rise speed 5mm / min, and printing temperature 25°C. The resin was cured layer by layer under ultraviolet light, and the texture forming agent was oriented along the printing path, initially forming a biomimetic texture structure. The model of the light-curing 3D printer is Form3L, with a resolution of 25μm, a build size of 335×200×300mm, a UV light source wavelength of 405nm, and a print layer thickness of 0.1-0.2mm. The resin is cured layer by layer under UV light, and the texture forming agent is directionally arranged along the printing path to initially form a bionic texture structure.

[0019] Use an ultrasonic cleaning machine to place the printed product in an ethanol solution (concentration 95%) and ultrasonically clean it for 10 minutes; then place the cleaned product in a UV curing box under ultraviolet light (intensity 8mW / cm 2 ) for 15 minutes; then, using a flat-bed vulcanizer, the secondary-cured product is placed in a mold with a bionic textured concave mold and embossed at a set pressure and temperature to further directional aggregate the texture forming agent, deepening the texture depth from 5-10 μm after printing to 20-30 μm; The ultrasonic cleaning machine model is KQ-500DE, which is used to remove uncured resin. Ultrasonic cleaning is performed for 10 minutes to remove uncured resin residue on the surface. The UV curing box model is UV-1000, which is used for secondary curing. The cleaned products are irradiated under UV light for 15 minutes to fully cure the resin and improve the mechanical properties. The model of the flatbed vulcanizing press is LB-D400×400, which is used for physical embossing to enhance realism and tactile feel.

[0020] Working principle: The raw materials are first pretreated (PBS drying, bamboo fiber alkali treatment, etc.), then gradiently mixed in a twin-screw compounder in a specific order to form a blended melt. After granulation, the melt is mixed with photoinitiators and other ingredients to form a photosensitive resin. After light-curing 3D printing, a preliminary 5-10μm texture is formed. Finally, through ultrasonic cleaning, UV secondary curing and flat-plate vulcanizer embossing (texture depth reaches 20-30μm), a bio-based leather with both environmental protection, mechanical properties and realistic texture is obtained.

[0021] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A PBS-based 3D printing method for preparing biomimetic textured bio-based leather, wherein the raw materials include the following ingredients: polybutylene succinate (PBS), bio-based polyester polyol, bamboo fiber, biodegradable elastomer (PCL elastomer), and biomimetic texture masterbatch; The ingredients and proportions are as follows: 50 parts of polybutylene succinate; 20 parts of bio-based polyester polyol; 15 parts of bamboo fiber; 10 parts of biodegradable elastomer; and 5 parts of bionic texture masterbatch. The following steps are also included: Step 1: Raw material pretreatment; Step 2: mixing raw materials; Step 3: Granulation process; Step 4: 3D printing; Step 5: Post-processing stage.

2. The PBS-based bio-based leather 3D printing preparation method according to claim 1, characterized in that: The polybutylene succinate was passed through an 80-mesh sieve and placed in a vacuum drying oven, and dried at 70°C and a vacuum degree of -0.09 MPa for 10 hours. The bio-based polyester polyol was vacuum-evacuated at room temperature for 30 minutes and then allowed to stand in a 40°C oven for 2 hours. The bamboo fiber was cut into 3-5 mm short fibers, passed through a 40-mesh sieve to remove overlong or overshort fibers, and then added with a 5% sodium hydroxide solution (liquid-to-solid ratio of 10:1). The fibers were placed in an 80°C autoclave and stirred for 2 hours, then washed with deionized water to a pH of 7, and finally dried at 60°C with forced air for 8 hours. The biodegradable elastomer was crushed into 1 cm×1 cm small pieces and preheated in a 50°C oven for 30 minutes. The biomimetic texture masterbatch was passed through a 100-mesh sieve and added to a high-speed mixer with 20% by mass of pretreated PBS particles, and mixed at 1500 r / min for 5 minutes.

3. The PBS-based bio-based leather 3D printing preparation method according to claim 1, characterized in that: The raw materials are mixed mainly using a twin-screw mixer, with the temperature of each zone set and the screw speed at 100 r / min. After the temperature stabilizes, polybutylene succinate is first added; 1 minute after the polybutylene succinate is added, polyester polyol is slowly added from a side feeding port; 2 minutes after the polyester polyol is added, the crushed biodegradable elastomer is added; 3 minutes after the elastomer is added, bamboo fiber is added through a fiber-specific feeding port; 5 minutes after the bamboo fiber is added, the pre-dispersed masterbatch is added; the total mixing time is 20 minutes.

4. The PBS-based biomimetic textured bio-based leather 3D printing preparation method according to claim 1, characterized in that: After the mixed material is extruded from the twin-screw die, it immediately enters the underwater pelletizing system, and after pelletizing, it is dehydrated and dried with hot air to obtain blended pellets with a moisture content of ≤0.5%.

5. The PBS-based biomimetic textured bio-based leather 3D printing preparation method according to claim 1, characterized in that: The blended particles were mixed with a photoinitiator (2 parts, such as TPO) and a reactive diluent (18 parts, such as trimethylolpropane triacrylate), and dissolved with stirring at 60°C for 2 hours to form a uniform resin. A 3D model with a biomimetic texture was designed using CAD software and imported into a light-curing 3D printer. The printing parameters were: exposure time 3 seconds / layer, layer thickness 0.15 mm, platform rise speed 5 mm / min, and printing temperature 25°C.

6. The PBS-based biomimetic textured bio-based leather 3D printing preparation method according to claim 1, characterized in that: Use an ultrasonic cleaning machine to place the printed product in an ethanol solution (concentration 95%) and ultrasonically clean it for 10 minutes; then place the cleaned product in a UV curing box under ultraviolet light (intensity 8mW / cm 2 ) for 15 minutes; then, using a flat-bed vulcanizer, the secondary-cured product is placed in a mold with a bionic texture cavity, and embossed at a set pressure and temperature to further directional aggregate the texture forming agent, deepening the texture depth from 5-10μm after printing to 20-30μm.

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