Color-changeable and degradable polylactic acid non-slip mat and production process thereof

Abstract

The invention discloses a color-changeable and degradable polylactic acid non-slip mat and a production process thereof, and belongs to the technical field of non-slip mat production processes, the non-slip mat adopts a three-layer composite structure: a surface layer contains a temperature-sensitive color-changing material, so that temperature response dynamic color change is realized; the pattern layer is combined with the photochromic component and the embossed structure to generate a multi-angle photoresponse three-dimensional effect; a biodegradation aid is added to the bottom layer, so that the environment friendliness is ensured. The production process comprises the steps of layered low-temperature co-extrusion casting, high-precision synchronous embossing and shaping, dual-band ultraviolet curing coating and continuous slitting and rolling. According to the scheme, the technical bottleneck that a traditional non-slip mat is single in function and mutually exclusive in chemical discoloration degradation is broken through, the product has the dynamic visual effect and the controllable degradation characteristic, meanwhile, the production efficiency is remarkably improved, and the non-slip mat is suitable for household non-slip scenes.

Description

Technical Field

[0001] The invention relates to the technical field of anti-skid pad production technology, in particular to a color-changing and degradable polylactic acid anti-skid pad and a production process thereof. Background Art

[0002] Currently, non-degradable polymer substrates (such as PVC and EVA) combined with surface embossing printing are commonly used in the field of household anti-slip mats. Although these materials can achieve basic anti-slip functions, they are subject to two major technical constraints: 1. Functional defects Single visual experience: Static embossed / printed patterns do not respond dynamically to changes in light or temperature, which can easily lead to aesthetic fatigue in consumers. Lack of environmental protection performance: The degradation cycle of petroleum-based plastics in the natural environment exceeds 100 years, and permanent microplastic pollution is formed after disposal, which violates the concept of sustainable development.

[0003] 2. Bottlenecks in Technology Upgrade The industry is trying to introduce bio-based materials such as polylactic acid (PLA) to replace traditional plastics, but is limited by the following key technical barriers: Poor functional compatibility: chemical color-changing formulas interfere with biodegradable components when directly mixed, resulting in color-changing failure or loss of control of the degradation cycle; Process limitations: High-temperature casting (>200°C) destroys the activity of thermochromic materials, and the synchronization accuracy of the embossing roller is low (error>0.3mm), making it difficult to achieve dynamic 3D effects; Low production efficiency: medium coating relies on a coating machine with a line speed of less than 80m / min and poor coating wear resistance.

[0004] While some research has explored separating functional layers through multi-layer structures, the lack of low-temperature molding processes and dynamic embossing control prevents them from achieving the desired combination of high-precision pattern discoloration, efficient degradation, and large-scale production. Therefore, developing an anti-slip mat technology that can synergistically address these challenges is an urgent need in the industry. Summary of the Invention

[0005] The main purpose of the present invention is to provide a color-changing and degradable polylactic acid anti-slip mat and a production process thereof, which can effectively solve the problems mentioned in the background technology.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A color-changing and degradable polylactic acid anti-slip mat, comprising: The 0.05-0.15mm surface layer is made of a blend of transparent polylactic acid (PLA) and thermochromic microcapsules. The microcapsules have a particle size of ≤20μm and contain thermochromic dyes with a response temperature range of 20-50°C. The 0.3-0.7mm pattern layer is composed of a transparent polylactic acid (PLA) / polyethylene vinyl acetate (PEVA) blend substrate, photochromic color particles that respond to ultraviolet light of 320-400nm, and an embossed 3D structure. The bottom layer of 0.2-0.6 mm is composed of transparent polylactic acid (PLA), a starch-based compatibilizer and a photosensitive degradation agent. The photosensitive degradation agent is a benzophenone derivative, and the addition amount is 0.5-1.0 wt%.

[0007] Through a three-layer physical isolation structure (surface layer - pattern layer - bottom layer), the temperature-sensitive material, photovariable material and degradation agent are completely separated to avoid chemical interference and simultaneously achieve dynamic color change and controllable degradation.

[0008] Preferably, the wall material of the thermosensitive color-changing microcapsules is melamine resin, and the core material comprises crystal violet lactone and dodecanol (mass ratio 1:3-5); The photochromic particles are spiropyran-titanium dioxide composites (particle size D50 ≤ 5 μm) with a grinding fineness of ≥ 350 mesh; The starch-based compatibilizer is maleic anhydride grafted cassava starch, with a grafting rate of ≥15% and an addition amount of 15-30wt%.

[0009] The limited melamine resin wall material ensures the temperature resistance of the microcapsules (>250°C), the spiropyran-titanium dioxide composite improves the UV response sensitivity, and the maleic anhydride grafted starch enhances the PLA / starch interface compatibility and solves the delamination defect.

[0010] A production process of a color-changing and degradable polylactic acid anti-slip mat comprises the following steps: S1. Raw material mixing and layered co-extrusion casting: The raw materials for each layer are mixed independently, and then the surface layer, pattern layer, and bottom layer are co-extruded through a three-channel extruder. The casting temperature gradient is controlled as follows: surface layer: 160±2℃, pattern layer: 165±2℃, bottom layer: 170±2℃; S2. Low-temperature embossing and synchronous shaping: The laser-aligned embossing roller group is used to emboss the 3D pattern at 80-90°C, and the synchronization error of the embossing roller is ≤0.05 seconds; S3, UV curing coating: Apply a fluorine-modified waterborne polyurethane protective layer on the surface, and cure it with a dual-band UV lamp: main band 365nm, auxiliary band 254nm. The coating thickness after curing is 5-10μm; S4, online slitting and winding: slitting speed 120-150m / min, winding tension adopts PID closed loop control (set value 18±0.5N).

[0011] Gradient temperature-controlled co-extrusion (160-170°C) is used to protect the activity of heat-sensitive materials, combined with laser alignment embossing (≤0.05 second error) to ensure the dynamic refraction accuracy of 3D patterns, and dual-band UV curing to achieve efficient and wear-resistant coatings.

[0012] Preferably, the inner wall of the surface extrusion channel of the three-channel extruder in S1 is provided with an aluminum nitride ceramic coating (thickness 1-3 μm), and the thermal conductivity coefficient is ≤5 W / m·K.

[0013] Preferably, the raw materials in S1 are mixed using a double-shaft vertical high-speed mixer, and the mixing process includes: Stage 1: Run at a low speed of 580±10 RPM for 2 minutes, then add PLA substrate and color particles; Stage 2: Run at high speed of 1160±20 RPM for 3 minutes, adding compatibilizer and degradation agent; Stage 3: Switch to medium speed 800±20 RPM and run for 2 minutes, with a total mixing time of 7±0.5 minutes; The final mixing temperature was controlled at 95±3°C.

[0014] The aluminum nitride ceramic coating blocks high-temperature conduction, and the three-stage mixing process (580 / 1160 / 800 RPM) optimizes the uniformity of color particle dispersion. The endpoint temperature is ≤95°C to prevent pre-activation of degradation agents.

[0015] Preferably, the embossing roller group in S2 is composed of an active roller and a driven roller, and the roller surface is laser engraved with a micro-pit array (pit depth 50-80 μm, density 200-300 pits / mm 2 ), the height value of the roller body is preset to 0.85±0.05mm through the finite element thermal deformation compensation algorithm.

[0016] Preferably, the embossing pressure in S2 is adjusted dynamically in real time, specifically: , where P is pressure / MPa and V is linear velocity / m / min.

[0017] Preferably, the fluorine-containing modified waterborne polyurethane protective layer in S3 is made of the following components: Water-based polyurethane emulsion (solid content 50%): 100 parts; Perfluoroalkyl acrylate (RF≥C6): 3-5 parts; Nano-silicon dioxide (particle size 20nm): 1-2 parts; Photoinitiator TPO: 0.5-1 part.

[0018] Preferably, the dual-band ultraviolet lamp irradiation parameters in S3 are: 365nm band: energy density 800-1000mJ / cm 2 , irradiation intensity 120-150mW / cm2 ; 254nm band: energy density 300-400mJ / cm 2 , irradiation intensity 40-60mW / cm 2 .

[0019] The fluorine-containing modified coating (perfluoroalkyl acrylate + nano-silica) forms a dense cross-linked network, and the dual-band UV curing (365nm main curing + 254nm deep initiation) makes the friction resistance coefficient exceed 6.5, reaching industrial-grade durability standards.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a layered composite structure design and a low-temperature dynamic embossing process, achieving a breakthrough in the compatibility of color-changing functionality and a degradable formulation through physical isolation. This is then combined with UV curing technology to enhance surface properties. Ultimately, this product combines dynamic light-temperature responsive color-changing properties with controllable biodegradability, significantly improving pattern accuracy and wear resistance, while significantly increasing production efficiency. This completely resolves the issues of traditional anti-slip mats with limited functionality and environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the production process of the present invention. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0023] like Figure 1 The production process flow diagram shown is described below in conjunction with a detailed embodiment.

[0024] 1. Raw material preparation and pretreatment 1.1 Preparation of surface materials The microcapsules were prepared using 95 parts by weight of transparent polylactic acid (PLA, NatureWorks 4032D) and 5 parts by weight of homemade thermochromic microcapsules. The microcapsules were prepared by mixing 1 gram of crystal violet lactone with 4 grams of dodecanol as the core material. The microcapsules were then coated with a 10% aqueous solution of melamine resin prepolymer via in-situ polymerization and cured at 60°C for 2 hours to obtain microcapsule particles with a size of 15-18 microns. During the raw material pretreatment stage, the PLA particles were first dehydrated in a vacuum drying oven at 80°C for 4 hours. The PLA particles were then mixed with the microcapsules in a double-cone mixer at a low speed of 30 rpm for 30 minutes. Mechanical shear was strictly controlled to prevent capsule rupture.

[0025] 1.2 Preparation of pattern layer materials A PLA / PEVA blend (7:3 mass ratio) and 8 parts photochromic pigment particles were used. For pigment particle preparation, 5 grams of spiropyran and 2 grams of 30-nanometer nano-titanium dioxide were mixed in a ball mill for 4 hours. The mixture was passed through a 350-mesh sieve, resulting in a sieve residue of ≤0.5%. The mixing process was performed in three stages: first, the PLA / PEVA mixture was placed in a vertical high-speed mixer and run at a low speed of 580 ± 10 rpm for 2 minutes. The pigment particles were then added and the speed was increased to 1160 ± 20 rpm for 3 minutes. Finally, the speed was reduced to 800 ± 20 rpm for 2 minutes. The temperature was monitored throughout the process, and the final temperature was strictly controlled at 93 ± 2°C.

[0026] 1.3 Preparation of base materials The formulation consists of 70 parts by weight of PLA (Total Corbion LX175), 25 parts by weight of maleic anhydride-grafted cassava starch with an 18% grafting rate, and 1.0 part by weight of the photodegradant 2,4-dihydroxybenzophenone. The mixing process is carried out at a constant temperature of 95°C and melt blended using a twin-screw extruder to prevent premature activation of the degradant during processing.

[0027] 2. Layered co-extrusion casting The surface extrusion process utilizes a seven-zone temperature-controlled extrusion channel, maintaining a stable temperature of 160±2°C throughout the entire process. A key innovation lies in the 2-micron-thick aluminum nitride ceramic coating deposited on the inner wall of the channel, reducing the thermal conductivity from 15 W / m·Kelvin (of the metal substrate) to 4.8 W / m·Kelvin. Infrared thermal imaging testing has shown that this design increases the microcapsule survival rate to over 98% (compared to less than 85% for uncoated devices).

[0028] Pattern layer extrusion process: Melt extrusion is performed at a constant temperature of 165±2°C using a special screw with a length-to-diameter ratio of 32:1. A barrier mixing element is placed in the front section of the screw to enhance dispersion, keeping the distribution uniformity (CV value) of the color-changing particles within the matrix within 5%, while also preventing particle decomposition due to local overheating.

[0029] The bottom layer extrusion process maintains a high temperature of 170±2°C to meet the plasticization requirements of the starch-enhancing system. The die slit is equipped with a 0.1mm precision adjustment mechanism to compensate for melt viscosity fluctuations caused by starch moisture absorption in real time, ensuring a stable bottom layer thickness tolerance within ±0.03mm.

[0030] The three melts converge and composite in a coat-hanger die. The die temperature is controlled in zones: 165°C at the junction of the surface and bottom layers, and 170°C in the center of the patterned layer. The resulting three-layer composite substrate has a total thickness of 1.0 ± 0.05 mm: the surface layer is 0.1 mm, the patterned layer is 0.6 mm, and the bottom layer is 0.3 mm.

[0031] 3. Low temperature embossing and simultaneous shaping The rollers utilize a custom laser-aligned embossing roller assembly from Bobst (BHS) Switzerland. The roller surface temperature is precisely maintained at 85±2°C via a thermal oil circulation system. Laser engraving technology creates an array of hexagonal pyramidal micro-pits on the roller surface, with a depth of 60 microns and a density of 250 pits per square millimeter. To minimize thermal deformation, a finite element simulation was used to preset a mid-height value of 0.88 mm on the roller surface to compensate for thermal expansion.

[0032] The core innovation lies in dynamic pressure control: real-time adjustment based on the formula: Pressure (MPa) = 0.6 + 0.01 × Line Speed (m / min). For example, at a line speed of 120 m / min, the system automatically adjusts the pressure to 1.8 MPa. The PLC collects line speed data every 0.1 seconds to dynamically adjust the hydraulic pressure output.

[0033] After embossing, a zoned air cooling system is activated immediately: the front zone uses German Lenze high-speed cold air (9.0±0.5 m / s, 25°C) to quickly set the micro-pit structure; the rear zone switches to low-speed warm air (6.0±0.5 m / s, 35°C) to slowly cool the surface and prevent internal stress cracking. Laser displacement sensor testing shows that this process reduces the synchronous difference in embossing refraction to less than 0.15 mm.

[0034] 4. UV-cured coating Coating formula: Based on 100 parts by weight of water-based polyurethane emulsion (Bayer Bayhydrol XP 2697), 4.5 parts by weight of perfluoroalkyl acrylate (Daikin Chemours FX-1800), 1.5 parts by weight of nanosilica (Evonik Aerosil 200) and 0.8 parts by weight of photoinitiator (IGM Resins TPO-L) were added.

[0035] Coating process: Using Japan Hirano HS-300 anilox roller coater, the coating amount is precisely controlled at 6.5 g / m2, and the wet film thickness is 15±1 microns.

[0036] Curing process: A dual-band UV system from IST Metz, Germany, was used. A 365 nm wavelength applied at an energy density of 900 mJ / cm² (irradiation intensity of 135 mW / cm²) to initiate crosslinking of the fluoroacrylate layer on the surface. A 254 nm wavelength applied at an energy density of 350 mJ / cm² (irradiation intensity of 50 mW / cm²) to activate photoinitiators deep within the coating, forming a gradient crosslinking network. The cured coating demonstrated a dry friction coefficient of 6.8 when tested according to ASTM D4060 (1 kg load, 1000 cycles).

[0037] 5. Online slitting and winding An Atlas ASL-1500 slitter is used, coupled with a Siemens S7-1500 PLC closed-loop control system. The slitting speed is set at 135 m / min (maximum design capacity 150 m / min). A taper strategy is used for tension control: the initial tension is 18 Newtons, decreasing linearly to 15 Newtons as the roll diameter increases. PID parameters are set to a proportional gain of 0.8 and an integral time of 1.2 seconds. A CCD visual correction system controls slitting deviation within ±0.3 mm. This design reduces the number of tape interruptions to less than one in eight hours of continuous production (compared to ≥5 with conventional processes).

[0038] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A color-changing and degradable polylactic acid anti-slip mat, characterized by: include: The 0.05-0.15mm surface layer is made of a blend of transparent polylactic acid and thermochromic microcapsules. The microcapsules have a particle size of ≤20μm and contain thermochromic dyes with a response temperature range of 20-50°C. The 0.3-0.7mm pattern layer is composed of a transparent polylactic acid / polyethylene-vinyl acetate blend substrate, photochromic color particles, and an embossed 3D structure. The photochromic color particles respond to ultraviolet light with a wavelength of 320-400nm. The bottom layer of 0.2-0.6 mm is composed of transparent polylactic acid, a starch-based compatibilizer and a photosensitive degradation agent. The photosensitive degradation agent is a benzophenone derivative, and the addition amount is 0.5-1.0 wt%.

2. The color-changing and degradable polylactic acid anti-slip mat according to claim 1, characterized in that: The wall material of the thermosensitive color-changing microcapsule is melamine resin, and the core material comprises crystal violet lactone and dodecanol (mass ratio 1:3-5); The photochromic particles are spiropyran-titanium dioxide composites with a particle size D50 ≤ 5 μm and a grinding fineness ≥ 350 mesh; The starch-based compatibilizer is maleic anhydride grafted cassava starch, with a grafting rate of ≥15% and an addition amount of 15-30wt%.

3. A process for preparing the color-changing and degradable polylactic acid anti-slip mat according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Raw material mixing and layered co-extrusion casting: The raw materials for each layer are mixed independently, and then the surface layer, pattern layer, and bottom layer are co-extruded through a three-channel extruder. The casting temperature gradient is controlled as follows: surface layer: 160±2℃, pattern layer: 165±2℃, bottom layer: 170±2℃; S2. Low-temperature embossing and synchronous shaping: The laser-aligned embossing roller group is used to emboss the 3D pattern at 80-90°C, and the synchronization error of the embossing roller is ≤0.05 seconds; S3, UV curing coating: Apply a fluorine-modified waterborne polyurethane protective layer on the surface, and cure it with a dual-band UV lamp: main band 365nm, auxiliary band 254nm. The coating thickness after curing is 5-10μm; S4, online slitting and winding: slitting speed 120-150m / min, winding tension adopts PID closed loop control.

4. The process for producing a color-changing and degradable polylactic acid anti-slip mat according to claim 3, characterized in that: The inner wall of the surface extrusion channel of the three-channel extruder in S1 is provided with an aluminum nitride ceramic coating, and the thermal conductivity coefficient is ≤5W / m·K.

5. The production process of the color-changing and degradable polylactic acid anti-slip mat according to claim 3, characterized in that: The raw materials in S1 are mixed using a twin-shaft vertical high-speed mixer. The mixing process includes: Stage 1: Run at a low speed of 580±10 RPM for 2 minutes, then add PLA substrate and color particles; Stage 2: Run at high speed of 1160±20 RPM for 3 minutes, adding compatibilizer and degradation agent; Stage 3: Switch to medium speed 800±20 RPM and run for 2 minutes, with a total mixing time of 7±0.5 minutes; The final mixing temperature was controlled at 95±3°C.

6. The production process of a color-changing and degradable polylactic acid anti-slip mat according to claim 3, characterized in that: The embossing roller group described in S2 consists of an active roller and a driven roller. The roller surface adopts a laser-engraved micro-pit array, and the height value of the roller body is preset to 0.85±0.05mm through the finite element thermal deformation compensation algorithm.

7. The process for producing a color-changing and degradable polylactic acid anti-slip mat according to claim 3, characterized in that: The embossing pressure in S2 is adjusted dynamically in real time. , where P is pressure / MPa and V is linear velocity / m / min.

8. The process for producing a color-changing and degradable polylactic acid anti-slip mat according to claim 3, characterized in that: The fluorine-containing modified waterborne polyurethane protective layer described in S3 is made of the following components: Water-based polyurethane emulsion: 100 parts; Perfluoroalkyl acrylate: 3-5 parts; Nano silicon dioxide: 1-2 parts; Photoinitiator TPO: 0.5-1 part.

9. The process for producing a color-changing and degradable polylactic acid anti-slip mat according to claim 3, characterized in that: The dual-band UV lamp irradiation parameters in S3 are: 365nm band: energy density 800-1000mJ / cm 2 , irradiation intensity 120-150mW / cm 2 ; 254nm band: energy density 300-400mJ / cm 2 , irradiation intensity 40-60mW / cm 2 .

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