Double-color forming process for shoemaking

Abstract

The invention discloses a two-color forming technology for shoemaking, and belongs to the technical field of shoemaking, the two-color forming technology for shoemaking comprises the steps that S1, a first pigment and a second pigment are prepared respectively, and the first pigment is prepared from a pouring type polyurethane elastomer, isolation type color paste and an anti-yellowing agent; the second pigment comprises the following raw materials: PTMG, MDI, BDO, mica sheets, nano aluminum oxide, inorganic color paste, a silane coupling agent, a dispersing agent, an antioxidant and a toughening agent; s2, carrying out injection molding on the first pigment, and carrying out plasma treatment; s3, putting the first pigment product subjected to plasma treatment into a shoe sole mold, and accurately positioning; injecting a second pigment into a sole mold, performing heat-preservation vulcanization treatment and cooling, demolding, and forming a double-color sole; and S4, trimming and cleaning the double-color shoe sole to obtain a final double-color shoe sole product. The sole product has the advantages of high interface bonding force, precise double-color effect, excellent functional performance and appearance texture.

Description

Technical Field

[0001] This invention mainly relates to the field of shoemaking technology, specifically a two-color molding process for shoemaking. Background Technology

[0002] With the continuous upgrading of functional and personalized demands for athletic shoes, GCU (thermosetting polyurethane elastomer composite) material soles, which combine wear resistance and slip resistance, have become a research hotspot in the industry. GCU material, due to its excellent tear strength, dynamic slip resistance, and weather resistance, is widely used in core functional areas such as shoe outsoles. Existing technologies have already produced shoe sole products that combine GCU material with EVA (ethylene-vinyl acetate copolymer) or supercritical foam midsoles. For example, patent CN118876308A discloses a method for integrally molding GCU soles, outsoles, and midsoles. This method involves placing a pre-fabricated EVA or supercritical midsole in a mold, then injecting GCU material and performing vacuum heating vulcanization to achieve integral molding of the GCU outsole and midsole. This initially solves the problems of delamination and degumming in traditional bonding processes, while simultaneously improving the wear resistance and slip resistance of the sole using GCU material.

[0003] In the field of two-tone shoe sole manufacturing, various integrated molding technologies have been developed. For example, patent CN119408073A discloses an injection molding mold and its production method for two-tone shock-absorbing shoe soles. This method proposes a step-by-step injection molding and movable mold core control process. First, an EVA outsole is injection molded in one step. Then, a vertically movable mold core is used to adjust the mold cavity, followed by a second injection molding of TPU (thermoplastic polyurethane) side support pads. Through vacuuming and precise temperature control via air channels, the integrated molding of two colors and two materials is achieved, avoiding the high labor costs and poor consistency of traditional bonding processes. Patent CN119699719A discloses a two-tone, dual-density shoe sole and its molding process. Using supercritical TPU as raw material, a heat-melting separator (hot melt adhesive film or TPU board) is set inside the mold. Two different colors of supercritical TPU beads are injected simultaneously. During a single physical foaming process, the separator melts to achieve the fusion of the two-tone interface, solving the problems of obvious two-tone boundaries and poor fusion in traditional step-by-step foaming.

[0004] While the aforementioned technologies have achieved integrated molding of two-tone or GCU soles, they still have significant limitations in practical applications, making it difficult to meet the comprehensive requirements of high-end athletic shoes for functional precision, interface durability, and aesthetic refinement.

[0005] 1. Insufficient uniformity of GCU material dispersion and interfacial bonding: In patent CN118876308A, the GCU material is only spread naturally through injection without optimization design for its flow characteristics and dispersion. It is easy to cause deviation in GCU layer thickness due to uneven local pressure in the mold cavity. Furthermore, the interfacial bonding between GCU and EVA / supercritical midsole relies solely on hot melt bonding without active modification of the substrate surface. Under long-term dynamic stress (such as running and jumping), interfacial peeling is prone to occur, and the peeling strength is usually lower than 2.5MPa, which cannot meet the requirements of high-intensity sports scenarios.

[0006] 2. Color migration and molding precision defects at the two-color interface: In the step-by-step injection molding process of patent CN119408073A, no design was made to prevent the migration of pigments between the two materials. The high temperature during the second injection of TPU can easily cause the color paste in the first injection of EVA to diffuse, resulting in blurred boundaries between the two colors. At the same time, the positioning accuracy of its movable mold core depends on the mechanical structure and no surface roughening process such as plasma treatment is introduced. The physical interlocking effect between the first and second materials is weak, and the impact resistance of the interface is insufficient.

[0007] 3. Difficulty in balancing material function and appearance performance: Patent CN119699719A uses supercritical TPU as a single material system. Although it can achieve dual density, the surface gloss of supercritical TPU is low and its yellowing resistance is poor, which cannot meet the requirements of high-end products for appearance and texture. At the same time, after its separator plate melts, it may leave trace impurities, affecting the uniformity of the internal structure of the sole and causing fluctuations in wear resistance.

[0008] Based on this, the present invention aims to solve the technical problems of uneven GCU dispersion, weak interface bonding, and color migration in existing GCU and two-color sole preparation technologies, so as to meet the comprehensive needs of high-end sports shoes. Summary of the Invention

[0009] This invention addresses the problem of overly simplistic solutions in existing technologies by providing a significantly different approach. It primarily offers a two-color molding process for shoemaking, enabling sole products to combine high interfacial bonding strength, precise two-color effects, excellent functional performance, and aesthetic appeal, thus meeting the comprehensive needs of high-end athletic shoes.

[0010] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0011] A two-color molding process for shoemaking includes the following steps:

[0012] S1. Prepare the first and second colorants respectively:

[0013] The first colorant comprises the following raw materials in parts by weight:

[0014] 100 parts of cast polyurethane elastomer (CPU);

[0015] 2-4 parts of isolating colorant;

[0016] 0.2-0.3 parts of anti-yellowing agent.

[0017] The second colorant comprises the following raw materials in parts by weight:

[0018] 100 parts of polytetrahydrofuran diol (PTMG);

[0019] 25-30 parts of diphenylmethane diisocyanate (MDI);

[0020] 1,4-Butanediol (BDO) 5-10 parts;

[0021] 8-12 portions of mica sheets;

[0022] 4-8 parts of nano-alumina;

[0023] Inorganic pigment paste 2.5-4 parts;

[0024] 0.5-1 part of silane coupling agent;

[0025] Dispersant 0.2-0.8 parts;

[0026] Antioxidant 0.1-0.5 parts;

[0027] Toughening agent 1.5-3 parts;

[0028] PTMG, MDI, and BDO are the raw materials for the GCU elastomer matrix, mica sheets and nano-alumina are the raw materials for the composite hard sheets, the GCU elastomer matrix serves as the soft phase matrix with a shell-like layered structure, and the composite hard sheets serve as the hard phase matrix with a shell-like layered structure.

[0029] S2. The first colorant is injection molded, and the first colorant product is placed in a plasma treatment machine for treatment. After treatment, the surface tension of the product is ≥40mN / m, which can improve the interfacial bonding activity with the main body of the shoe sole; the surface roughness Ra after treatment is 0.8-1.2μm, which can enhance physical interlocking.

[0030] S3. Place the plasma-treated first colorant product into the shoe sole mold and position it precisely with a positioning accuracy of ±0.02mm; then inject the second colorant into the shoe sole mold, and after heat preservation vulcanization and cooling, demold to form a two-color shoe sole.

[0031] S4. Trim and clean the two-tone soles to obtain the final two-tone sole product.

[0032] In existing technologies, dual-material composites rely on physical thermal bonding (such as the thermal bonding of GCU and EVA in CN118876308A, and the melting of the separator in CN119699719A), without involving chemical interface modification. Those skilled in the art generally believe that CPUs have low levels of surface-active groups (-OH, -NH) (typically <0.3 mmol / m²), resulting in weak chemical reactivity with GCU (containing isocyanate groups). Direct composites are prone to delamination due to insufficient interfacial bonding. Furthermore, hard layers (such as mica sheets and nano-alumina) further weaken the interfacial contact area, exacerbating the risk of delamination between the sole body and the other colorant. This inherent concern about interfacial compatibility has led researchers to actively avoid CPU-GCU composite solutions. However, this invention increases the surface-active groups of the CPU to ≥0.7 mmol / m² through plasma treatment; and bridges the CPU and GCU using a silane coupling agent. This combination overcomes this prejudice and represents a previously unexplored chemical modification approach in the field.

[0033] In existing technologies, the anti-color migration treatment for two-color adhesive-free bonding relies on physical isolation: from the fixed partition to the movable mold core, it does not break through the framework of mechanical barriers. Those skilled in the art generally believe that the essence of two-color color migration is the physical diffusion of pigment molecules, which is blocked by mold structures or temporary separators, without ever considering starting from the pigment itself and limiting its diffusion ability through chemical coating. However, the isolation-type color paste (polyurethane-coated pigment) of this invention locks the pigment molecules in place through the coating layer, preventing migration even at the high temperatures of GCU vulcanization. This chemical control approach completely breaks through the existing technical framework of physical isolation.

[0034] In existing technologies, interfacial bonding relies on a single mechanism: for example, CN118876308A relies on the thermal fusion during GCU vulcanization and the fusion bonding with the EVA surface; CN103009553A relies on the self-adhesion during EVA injection foaming; and CN116749435A relies on the fusion cross-linking of the third mold cavity to form physical interlocking. Technicians have never realized that chemical bonding and physical roughening can both enhance interfacial bonding. This invention uses plasma treatment to achieve a CPU surface roughness Ra=0.8-1.2μm (improving physical interlocking), and uses a silane coupling agent to bridge the -OH of the CPU and the -NCO of the GCU, forming chemical bonds and increasing the peel strength to ≥3.0MPa. This dual-strength approach breaks through the existing understanding of relying solely on chemical or physical methods.

[0035] In existing technologies, those skilled in the art generally believe that the wear resistance, shock absorption, and impact resistance of shoe soles can be achieved simply by adjusting material composition or through macroscopic zoning design, without the need to introduce complex biomimetic layered structures. This bias fundamentally blocks the innovative direction of structural biomimicry. The core logic of those skilled in the art is that as long as there are differences in the hardness, density, and wear resistance of the two materials, zonal composites can meet the functional requirements, without ever considering further enhancing performance synergy through microstructural design (such as layering). The core of the shell-like layered structure in this application is the synergistic effect of the soft phase matrix (GCU) and the oriented hard phase layers (mica / nano-alumina) (the hard layer resists impact, and the soft layer absorbs energy). This approach, where structure determines performance, completely breaks away from the inherent framework of composition determining performance in the footwear industry.

[0036] Further, in step S1, the preparation of the first colorant includes the following steps:

[0037] (1) Weigh out the cast polyurethane elastomer and place it in a mixing device for stirring;

[0038] (2) Add the isolating color paste and anti-yellowing agent to the mixing equipment according to the specified ratio;

[0039] (3) Control parameters: temperature 75-85℃, speed 150-250rpm, stirring for 10-20min to obtain the first colorant.

[0040] Furthermore, in step S1, the preparation of the second colorant includes the following steps:

[0041] (1) Weigh out polytetrahydrofurandiol, diphenylmethane diisocyanate and 1,4-butanediol according to the proportion, mix them at 60-80℃ for 15-25 min to obtain GCU elastomer matrix, and put it into an extruder;

[0042] (2) Weigh out mica sheets and nano-alumina, mix them, and dry them at 110-130℃ for 1-3 hours; then add 0.2% of the total amount of mica sheets and nano-alumina as silane coupling agent, mix them evenly, and obtain a hard sheet layer;

[0043] (3) Introduce the GCU elastomer matrix into the melting section of the extruder and control the temperature at 190-200℃. After the GCU elastomer matrix melts, add the hard sheet, dispersant, inorganic color paste, remaining silane coupling agent, antioxidant and toughening agent.

[0044] (4) Control the extrusion temperature: 175±3℃ for the feeding section, 195±5℃ for the melting section, and 200±3℃ for the die head section; the screw speed is 250-350rpm, the granulation particle size is 3-5mm, and the second colorant granules are obtained.

[0045] (5) Dry the second colorant particles at 100-110℃ for 3.5-4.5h, and the moisture content of the particles is ≤0.08% to obtain the second colorant.

[0046] Furthermore, the specific steps of step S2 are as follows:

[0047] (1) Use a mold that matches the target shape of the first colorant and preheat it to 55-65℃;

[0048] (2) Inject the first colorant into the mold, control the injection temperature to 90-95℃, the injection pressure to 48-55MPa, the injection speed to 25-35mm / s, the holding pressure to 35-45MPa, and the holding time to 8-12s;

[0049] (3) Use a chiller to control the temperature and cool the medium at 20°C. Cool to 40±2°C and then demold.

[0050] (4) Place the first pigment product into the plasma treatment machine, control parameters: power 480-520W, treatment time 25-35s.

[0051] Furthermore, in step S3, the shoe sole mold is first preheated to 80-90℃, and then the first colorant product after plasma treatment is placed in it;

[0052] And / or, the positioning accuracy of the precise positioning is ±0.02mm.

[0053] Furthermore, in step S3, when the second colorant is injected into the shoe sole mold, the pouring temperature is controlled at 95±3℃, the pouring pressure is 0.2-0.4MPa, and the pouring speed is 40-60mL / s;

[0054] And / or, use step-by-step pouring, first fill 1 / 3 of the shoe sole mold cavity, pause for 1-3 seconds, and then fill to the full.

[0055] Furthermore, in step S3, the heat preservation vulcanization treatment is as follows: heat preservation vulcanization at 95-105℃ for 25-35 min, and then cooling down to 80±3℃ at a cooling rate of 2-3℃ / min in the later stage of vulcanization.

[0056] And / or, the cooling is as follows: first cool to 60±2℃ at a rate of 3℃ / min, then cool to 50±2℃ at a rate of 2℃ / min.

[0057] Furthermore, in step S3, after demolding, the sole is placed in a constant temperature and humidity environment of 20-25℃ and 45%-55%RH for 20-30 hours to stabilize the shell-like layered structure.

[0058] Furthermore, in step S4, trimming involves removing excess material from the edge of the sole with a trimming accuracy of ±0.1mm. The trimming direction is consistent with the layered arrangement direction to avoid damaging the main layered structure.

[0059] Further, in step S4, cleaning is performed by wiping the surface of the shoe sole with anhydrous ethanol to remove residual release agent; after cleaning, the sole is allowed to air dry naturally.

[0060] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0061] (1) The first colorant of this invention is an isolating colorant coated with polyurethane. During the vulcanization process of the second colorant, the coating layer can prevent pigment molecules from migrating to the GCU matrix. At the same time, in conjunction with the process of precise positioning of the first colorant in the shoe sole mold after pre-forming, the precise boundary between the two colors is ensured. The prior art relies solely on physical isolation of the mold, which cannot control color migration at the pigment molecule level. However, this application achieves source-level color migration prevention through chemical coating, significantly improving the refinement of the two-color appearance. That is, this invention achieves the effect of clear two-color boundary without color migration by using the principle of physically locking pigment molecules and blocking pigment diffusion during high-temperature vulcanization through the coating layer. Compared with the prior art, it solves the industry pain point of easy color migration and blurred boundaries in high-temperature molding of two-color shoe soles.

[0062] (2) After plasma treatment, the surface tension of the CPU in the first colorant product of this invention is increased to ≥40mN / m, and the wettability with GCU is significantly enhanced. The epoxy groups of the silane coupling agent react with the -OH on the CPU surface, and the siloxane groups crosslink with the -NCO of GCU, forming a dual interface bond of physical interlocking and chemical bonding. Ultimately, the interface peel strength and simply supported beam impact strength are improved, which can meet the interface stability requirements under high-intensity sports scenarios. That is, this invention uses the principle of plasma to enhance the surface active groups and roughness of the CPU to achieve physical interlocking, and the silane coupling agent to bridge the -OH of the CPU and the -NCO of GCU to form chemical bonds, achieving the effect of high peel strength of the two-color interface. Compared with the prior art, it solves the core problems of easy delamination and poor impact resistance of the two-color / two-material sole interface.

[0063] (3) In this invention, the second colorant used to prepare the main body of the shoe sole uses GCU elastomer (PTMG+MDI+BDO) as a soft phase matrix to ensure compression rebound rate, thereby optimizing the shock absorption performance of the shoe sole. Mica sheets and nano-alumina composite hard sheets are added to form a shell-like layered structure, which can improve the wear resistance of the shoe sole. Furthermore, the first colorant uses CPU mixed color paste and anti-yellowing agent, and achieves a better decorative effect through high-gloss mold injection molding. The first and second colorants form a composite structure through injection molding, breaking the inherent limitations of existing technologies where pursuing gloss inevitably sacrifices wear resistance, and pursuing function inevitably sacrifices appearance, thus meeting the dual demands of high-end sports shoes for both texture and performance. In other words, this invention utilizes the synergistic principle of CPU providing decoration, GCU matrix ensuring elastic shock absorption, and hard sheets enhancing wear resistance to achieve a balance between appearance and high functional performance. Compared with existing technologies, it solves the technical contradiction in the shoe manufacturing field where appearance and function must be sacrificed.

[0064] (4) This invention controls the screw shearing rate to ensure that the hard layers are not over-sheared; controls the flow rate of the liquid feed front to ensure the consistency of layer orientation; and uses step-by-step cooling to avoid internal stress at the interface due to temperature differences. The final product dimensional accuracy is controlled within ±0.03mm, and the layered structure qualification rate is ≥99.5%, breaking through the cognitive limitations of existing technologies where macroscopic processes cannot control microscopic structures, and realizing the industrial mass production of biomimetic structures. That is, this invention achieves stable mass production and high dimensional accuracy of shell-like layered structures by precisely controlling the morphology of the layers, avoiding interlayer internal stress, and stabilizing the layered structure.

[0065] (5) This invention avoids damage to the sheets by controlling the screw shearing rate; it guides the orientation of the sheets by controlling the flow rate of the liquid material, so that the hard sheets are arranged parallel to the direction of force on the sole, forming a hard layer that resists impact and a soft layer that absorbs energy, similar to the pearl layer of a seashell. The hard sheets can resist ground friction and impact, and the soft phase GCU matrix can absorb the impact force of movement, breaking the performance limitations of the prior art where improving wear resistance inevitably reduces shock absorption and improving shock absorption inevitably sacrifices wear resistance. That is, this invention achieves the effect of synergistic improvement of wear resistance and shock absorption performance by utilizing the synergistic effect of the hard sheets parallel to the direction of force and the soft phase GCU matrix with a layer spacing of 5-10μm for impact resistance and energy absorption and buffering. Compared with the prior art, it solves the performance defect of the sole where wear resistance and shock absorption are difficult to balance.

[0066] (6) The second colorant of this invention adopts a step-by-step pouring method, first filling 1 / 3 of the cavity, pausing for a few seconds, and then filling to the full, to avoid the interface bubbles caused by the liquid material directly impacting the CPU preform; the static process after demolding allows the GCU matrix to fully cross-link and the hard layer position to stabilize, reducing performance fluctuations. Existing technologies mostly use one-time filling or foaming and then ship directly, which is prone to high defect rates due to bubbles and unstable structures. However, this invention reduces the defect rate through process optimization, significantly improving the economic efficiency of mass production. That is, this invention uses the principle of step-by-step filling of the cavity to avoid the liquid material impacting the CPU preform, and the constant temperature and humidity static setting to stabilize the layered structure, to achieve the effect of bubble-free and stable performance of the product. Compared with existing technologies, it solves the production problems of low pass rate and poor performance consistency in the mass production of two-color integrated shoe soles.

[0067] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0068] Figure 1 This is a process flow diagram of the present invention;

[0069] Figure 2 This is a product illustration of Embodiment 1 of the present invention. Detailed Implementation

[0070] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0072] Example 1: Please refer to the appendix for details. Figure 1 A two-color molding process for shoemaking includes the following steps:

[0073] I. Raw Material Preparation

[0074] 1. First colorant: 100 parts of high-gloss CPU (BASF 1185A) with a water content ≤0.1%, 3 parts of isolation-type color paste (encapsulated pigment, polyurethane coating, using organic purple pigment) with a solid content of 30-35%, and 0.2 parts of anti-yellowing agent UV-327. The proportions of each substance are based on 100 parts of high-gloss CPU.

[0075] 2. Second colorant: GCU elastomer matrix (100 parts PTMG + 28 parts MDI + 7 parts BDO), composite hard sheets (10 parts mica sheets + 6 parts nano alumina, particle size 100-150 mesh, sheet diameter-to-thickness ratio 45:1), inorganic color paste (carbon black pigment) 3.2 parts, silane coupling agent KH-560 0.6 parts, dispersant BYK-966 0.4 parts, antioxidant 1010 0.3 parts, toughening agent EVA-g-MAH 2 parts. The proportions of each substance are based on 100 parts PTMG.

[0076] II. Preparation of the two pigments

[0077] 1. The preparation of the first colorant includes the following steps:

[0078] (1) Weigh the CPU chip (BASF 1185A) and put it into a vacuum mixer;

[0079] (2) Add the isolating color paste and anti-yellowing agent to the vacuum mixer according to the specified ratio;

[0080] (3) The control parameters are: temperature 80℃, rotation speed 200rpm, vacuum degree -0.09MPa, stirring for 15min; after stirring, the liquid has no visible color spots or bubbles, and no visible additive particles.

[0081] (4) Transfer it to the barrel of the CPU injection molding machine and keep it warm at 85°C for later use.

[0082] 2. The preparation of the second colorant includes the following steps:

[0083] (1) Weigh PTMG, MDI and BDO according to the proportion, mix them in a vacuum mixer at 70℃ for 20 min, control the viscosity of the prepolymer at 25℃ to be 800-1000 mPa·s, and obtain GCU elastomer matrix, and put it into the feeding section 1 of the twin-screw extruder;

[0084] (2) Mix mica sheets and nano-alumina in a ratio of 5:3 and dry at 120℃ for 2 hours; then add 0.2% of KH-560 of the total amount of mica sheets and nano-alumina, mix evenly, and obtain a hard sheet layer; the moisture content of the composite hard sheet layer is ≤0.05%, and KH-560 uniformly coats the surface of the sheet layer to enhance compatibility with the soft phase matrix;

[0085] (3) The GCU elastomer matrix enters the melting section of the extruder and the temperature is controlled at 195℃. After the GCU elastomer matrix melts, the hard sheet and dispersant BYK-966 are added from the side feed port. The inorganic color paste, the remaining KH-560, antioxidant 1010 and toughening agent EVA-g-MAH are added from the die head section. The temperature of the side feed port is controlled at 190℃ to avoid high-temperature decomposition of the hard sheet. The dispersant must be added at the same time as the hard sheet to ensure the orientation effect.

[0086] (4) Controlling the extrusion temperature: 175℃ for the feeding section, 195℃ for the melting section, and 200℃ for the die head section; the screw speed is 300 rpm, the granulation particle size is 3-5 mm, and the screw shear rate is measured to be 110 s under the conditions of material temperature of 195℃ and screw groove depth of 3 mm. -1 The second colorant granules are obtained; the screw shear rate is precisely controlled to avoid excessive shearing and damage to the hard sheets, and the aspect ratio is maintained at ≥40:1; the granules after granulation should not have obvious agglomeration.

[0087] (5) Dry the second colorant particles at 105℃ for 4 hours, with a particle moisture content of ≤0.08%; transfer them to the casting system tank, keep them at 90℃, and stir the liquid at 55rpm; stir at low speed during the heat preservation stage to prevent the hard sheets from settling; the liquid layer structure is pre-oriented (the stirring direction is consistent with the subsequent casting flow direction).

[0088] III. Injection Molding

[0089] 1. Injection molding of the first colorant, including the following steps:

[0090] (1) Use a mold that matches the target shape of the first colorant, preheat to 60°C, and perform high-gloss treatment on the cavity; the mold cavity must be clean and free of impurities to avoid affecting the surface gloss of the decorative parts;

[0091] (2) Inject the first colorant into the mold, control the injection temperature to 90-95℃, the injection pressure to 50MPa, the injection speed to 30mm / s, the holding pressure to 40MPa, and the holding time to 10s; during the holding stage, avoid the formation of shrinkage cavities inside the first colorant product.

[0092] (3) Use a chiller to control the temperature and cool. The temperature of the cooling medium is 20℃, the cooling rate is 3℃ / min, and the product is cooled to 40℃ before demolding. The cooling rate is ≤5℃ / min. The cooling rate is uniform to avoid internal stress and uneven color of the first color product due to excessive temperature difference.

[0093] (4) Inspect the first pigment product: uniform color (ΔE≤0.7), no bubbles / burrs on the surface, dimensional accuracy ±0.03mm, and surface active group content ≥0.7mmol / m 2 The content of surface-active groups was verified by XPS detection.

[0094] (5) Place the qualified first color product into the plasma treatment machine. Control parameters: power 500W, treatment time 30s, gas flow rate 20L / min, and the gas is a mixture of argon and oxygen at a ratio of 9:1. After treatment, the surface tension of the product is ≥40mN / m, which can improve the interfacial bonding activity with the main body of the shoe sole. After treatment, the surface roughness Ra=0.8-1.2μm can enhance physical interlocking.

[0095] 2. The second colorant injection molding process includes the following steps:

[0096] (1) Preheat the shoe sole mold to 85°C to match the mold temperature with the heat preservation temperature of the second color material, so as to avoid the rapid cooling of the liquid material after contact and affect the forming of the layered structure.

[0097] (2) Place the plasma-treated first colorant product into the shoe sole mold and position it precisely according to the design position, with a positioning accuracy of ±0.02mm; after the mold is closed, press the fluororubber sealing ring at the edge of the cavity to ensure a tight seal;

[0098] (3) Inject the second colorant into the shoe sole mold, control the pouring temperature at 95℃, the pouring pressure at 0.3MPa, the pouring speed at 50mL / s, and the flow front speed of the liquid at 1.0mm / s; adopt step-by-step pouring, first fill 1 / 3 of the cavity, pause for 2s and then fill to the full, the liquid flows along the cavity wall to avoid direct impact on the first colorant product; the flow front speed is stable to ensure that the hard sheets are oriented along the flow direction and the sheet plane is parallel to the flow direction;

[0099] (4) Keep the temperature at 100℃ for 30 min and then reduce the temperature to 80℃ at a rate of 2℃ / min during the later stage of the vulcanization; ensure that the soft phase matrix is ​​fully cross-linked and the hard sheets are firmly bonded to the matrix; during the reaction, the isocyanate groups in the main GCU material and the surface active groups of the first pigment product form chemical bonds through KH-560, and the hard sheets are oriented to form a layered structure with an interlayer spacing of 5-10μm; in addition, the isolation type pigment coating prevents the diffusion of pigment molecules, achieving dual anti-color migration through chemical bonding and physical isolation;

[0100] (5) First cool to 60°C at a rate of 3°C / min, then cool to 50°C at a rate of 2°C / min, and demold. Use negative pressure adsorption (adsorption force 3N) during demolding to avoid scratching the surface; slow cooling can avoid thermal stress cracking at the two-color interface.

[0101] (6) After demolding, the soles are placed in a constant temperature and humidity environment of 23℃ and 50% RH for 24 hours to stabilize the shell-like layered structure, resulting in a product as shown in the image. Figure 2 As shown.

[0102] IV. Post-processing

[0103] 1. Trimming: An automated trimming machine is used to remove excess material from the edges of the sole, with a trimming accuracy of ±0.1mm and no processing marks on the surface; the trimming direction is consistent with the layered arrangement direction to avoid damaging the main layered structure;

[0104] 2. Cleaning: Wipe the surface of the shoe sole with anhydrous ethanol to remove residual mold release agent; after cleaning, let it air dry naturally in an explosion-proof fume hood (ventilation speed ≥0.5m / s), avoid high temperature baking (≤60℃), and keep away from open flames.

[0105] V. Quality Inspection

[0106] 1. Color detection, including:

[0107] (1) Color difference test: Use CR-400 colorimeter to test 5 points and take the average value; the qualified standard is that the first color product ΔE≤0.7 and the sole body ΔE≤1.0.

[0108] (2) No color migration verification: First soak in 60℃ hot water for 24 hours, then age at 70℃ for 48 hours; the qualified standard is no color migration and clear boundary between the two colors.

[0109] 2. Performance testing, including:

[0110] (1) Interface bonding strength: Refer to GB / T 15256-2014, the qualified standard is peel strength ≥3.0MPa (no delamination).

[0111] (2) Wear resistance: According to GB / T 3903.2-2017, the qualified standard is Taber wear ≤11mg / 1000 revolutions.

[0112] (3) Impact resistance: Refer to GB / T 1843-2008, the qualified standard is that the impact strength of a simply supported beam is ≥23kJ / m².

[0113] (4) Characterization of layered structure: SEM observation (magnification 50 times), the qualified standard is interlayer spacing of 5-10 μm, no aggregation / peeling.

[0114] Example 2: The difference between this example and Example 1 is that:

[0115] In the raw material preparation steps, the first colorant consists of: 100 parts of high-gloss CPU, 2 parts of isolating colorant, and 0.3 parts of anti-yellowing agent.

[0116] Second colorant: 100 parts PTMG, 25 parts MDI, 10 parts BDO, 8 parts mica flakes, 8 parts nano alumina, 2.5 parts inorganic color paste, 0.5 parts silane coupling agent KH-560, 0.2 parts dispersant, 0.1 parts antioxidant, and 1.5 parts toughening agent.

[0117] In the preparation step of the first colorant, the control parameters are: temperature 75℃, rotation speed 150rpm, and stirring for 20min.

[0118] In the preparation of the second colorant, PTMG, MDI, and BDO were weighed in proportion and mixed in a vacuum mixer at 60℃ for 25 minutes; mica flakes and nano-alumina were mixed and dried at 110℃ for 3 hours; the temperature of the extruder melting section was controlled at 190℃; the extrusion temperature was controlled as follows: feeding section 172℃, melting section 190℃, and die head section 197℃; the screw speed was 250 rpm; and the second colorant particles were dried at 100℃ for 4.5 hours.

[0119] In the first colorant injection molding step, the mold is preheated to 55℃; the injection temperature is controlled at 90-95℃, the injection pressure at 48MPa, the injection speed at 25mm / s, the holding pressure at 35MPa, and the holding time at 12s; the mold is then demolded after cooling to 38℃; the plasma treatment machine control parameters are: power 480W, treatment time 35s.

[0120] In the second color material injection molding step, the shoe sole mold is preheated to 80℃; when the second color material is injected into the shoe sole mold, the pouring temperature is controlled at 92℃, the pouring pressure at 0.4MPa, and the pouring speed at 60mL / s; the shoe sole is kept at 95℃ for 35min for vulcanization, and then cooled to 77℃ at a cooling rate of 3℃ / min in the later stage of vulcanization; the shoe sole is first cooled to 58℃ at a rate of 3℃ / min, and then cooled to 48℃ at a rate of 2℃ / min for demolding; after demolding, the shoe sole is placed in a constant temperature and humidity environment of 20℃ and 45% RH for 30h.

[0121] Everything else is the same as in Example 1.

[0122] Example 3: The difference between this example and Example 1 is that:

[0123] In the raw material preparation steps, the first colorant consists of: 100 parts high-gloss CPU, 4 parts isolating colorant, and 0.2 parts anti-yellowing agent.

[0124] Second colorant: 100 parts PTMG, 30 parts MDI, 5 parts BDO, 12 parts mica flakes, 4 parts nano alumina, 4 parts inorganic color paste, 1 part silane coupling agent KH-560, 0.8 parts dispersant, 0.5 parts antioxidant, and 3 parts toughening agent.

[0125] In the preparation step of the first colorant, the control parameters are: temperature 85℃, rotation speed 250rpm, and stirring for 10min.

[0126] In the preparation of the second colorant, PTMG, MDI, and BDO were weighed in proportion and mixed in a vacuum mixer at 80℃ for 15 minutes; mica flakes and nano-alumina were mixed and dried at 130℃ for 1 hour; the temperature of the extruder melting section was controlled at 200℃; the extrusion temperature was controlled as follows: 178℃ for the feeding section, 200℃ for the melting section, and 203℃ for the die head section; the screw speed was 350 rpm; and the second colorant particles were dried at 110℃ for 3.5 hours.

[0127] In the first colorant injection molding step, the mold is preheated to 65℃; the injection temperature is controlled at 90-95℃, the injection pressure at 55MPa, the injection speed at 35mm / s, the holding pressure at 45MPa, and the holding time at 8s; the mold is then demolded after cooling to 42℃; the plasma treatment machine control parameters are: power 520W, treatment time 25s.

[0128] In the second color material injection molding step, the shoe sole mold is preheated to 90℃; when the second color material is injected into the shoe sole mold, the pouring temperature is controlled at 98℃, the pouring pressure at 0.2MPa, and the pouring speed at 40mL / s; the shoe sole is vulcanized at 105℃ for 25min, and then cooled to 83℃ at a rate of 3℃ / min in the later stage of vulcanization; the shoe sole is first cooled to 62℃ at a rate of 3℃ / min, and then cooled to 52℃ at a rate of 2℃ / min, and then demolded; after demolding, the shoe sole is placed in a constant temperature and humidity environment of 25℃ and 55% RH for 20h.

[0129] Everything else is the same as in Example 1.

[0130] Example 4: The difference between this example and Example 1 is that:

[0131] In this embodiment, during the first colorant injection molding step, the produced first colorant product has a thickness allowance. The bottom of the shoe sole mold has a recessed groove adapted to the first colorant product, and its depth is exactly equal to the thickness allowance of the first colorant product. When the first colorant product is placed into the shoe sole mold, precise positioning can be achieved by placing the first colorant product within the groove. After the second colorant injection molding, the thickness allowance of the first colorant product is removed, that is, the portion of the first colorant product protruding from the shoe sole is cut off, so that the first colorant product is completely embedded in the surface of the finished shoe sole.

[0132] Everything else is the same as in Example 1.

[0133] Comparative Example 1: The difference from Example 1 is that:

[0134] Replace the isolated pigment paste (polyurethane-coated organic purple pigment) in the first pigment with ordinary organic purple pigment (without polyurethane coating).

[0135] Everything else is the same as in Example 1.

[0136] Comparative Example 2: The difference from Example 1 is that:

[0137] The first pigment product was not subjected to plasma treatment.

[0138] Everything else is the same as in Example 1.

[0139] Comparative Example 3: The difference from Example 1 is that:

[0140] No silane coupling agent was added to the second colorant.

[0141] Everything else is the same as in Example 1.

[0142] Comparative Example 4: The difference from Example 1 is that:

[0143] The second colorant has no composite hard sheet layer, that is, no mica sheets and nano-alumina.

[0144] Everything else is the same as in Example 1.

[0145] Comparative Example 5: The difference from Example 1 is that:

[0146] The second colorant is poured in one go, eliminating the need for step-by-step pouring.

[0147] Everything else is the same as in Example 1.

[0148] Comparative Example 6: The difference from Example 1 is that:

[0149] The second colorant was not subjected to constant temperature and humidity settling treatment after demolding during the injection molding process.

[0150] Everything else is the same as in Example 1.

[0151] Comparative Example 7: The difference from Example 1 is that:

[0152] The first colorant did not contain any anti-yellowing agent.

[0153] Everything else is the same as in Example 1.

[0154] Comparative Example 8: The difference from Example 1 is that:

[0155] The two-color adhesive-free connection is made using a single GCU material. The main raw material of the first and second colorants is GCU, but the inorganic color pastes are different. The connection is achieved by melting the hot melt separator (TPU film), without plasma treatment or silane coupling agent.

[0156] Everything else is the same as in Example 1.

[0157] Comparative tests were conducted on the products of Examples 1-4 and Comparative Examples 1-8 as described above:

[0158] 1. Color difference (ΔE)

[0159] Using a CR-400 colorimeter, five test points were randomly selected on the sole (two in the first color area and three in the second color area), and the average value was taken.

[0160] 2. Color transfer performance

[0161] First, soak in 60℃ deionized water for 24 hours, then dry it, and age it in an aging chamber at 70℃ for 48 hours. Observe whether the color migration at the two-color boundary occurs.

[0162] 3. Interfacial peel strength (MPa)

[0163] A 180° peel test was conducted at a tensile speed of 50 mm / min. The average value of the three test groups was taken. Refer to GB / T 15256-2014.

[0164] 4. Taber wear (mg / 1000 rpm)

[0165] Use a Taber abrasion tester with a load of 1000g and a speed of 1000 rpm to weigh and calculate the abrasion amount; refer to GB / T 3903.2-2017.

[0166] 5. Impact strength of a simply supported beam (kJ / m²)

[0167] The sample size is 80mm×10mm×4mm (taken from the core stress area of ​​the sole), without any gaps, and the average value is taken from 3 sets of tests; refer to GB / T 1843-2008.

[0168] 6. Layered structure integrity (%)

[0169] SEM was used to observe cross-sections at 50x magnification, and the proportion of samples with interlayer spacing of 5-10 μm and no aggregation / exfoliation was statistically analyzed.

[0170] 7. Yellowing Resistance Index (ΔYI)

[0171] After aging the xenon arc lamp for 100 hours, the color difference was tested using a CR-400 colorimeter; refer to GB / T 16422.2-2014.

[0172] 8. Product bubble rate (%)

[0173] 100 pieces were randomly selected, and X-ray flaw detectors were used to detect bubbles with a diameter ≥0.1mm. The failure rate was calculated; refer to QB / T2882-2013.

[0174] 9. Dimensional accuracy (mm)

[0175] The coordinate measuring machine is used to test the length, width, and thickness, and the average value is taken after 5 tests. The deviation from the design value is then calculated.

[0176] 10. Surface gloss (GU)

[0177] The first pigment area was tested using a 60° angle gloss meter.

[0178] The test data are shown in Tables 1-1 and 1-2.

[0179] Table 1-1 Detection Data of Examples and Comparative Examples

[0180] Sample number Color difference (ΔE) Color bleeding Peel strength (MPa) Taber wear (mg) Impact strength (kJ / m²) Example 1 0.5 / 0.8 none 3.2 10.0 24.0 Example 2 0.6 / 0.9 none 3.0 11.0 23.0 Example 3 0.4 / 0.7 none 3.3 9.5 25.0 Example 4 0.5 / 0.8 none 3.4 9.8 24.5 Comparative Example 1 1.8 / 2.2 obvious migration 3.1 10.2 23.8 Comparative Example 2 0.5 / 0.8 none 2.0 10.1 20.0 Comparative Example 3 0.5 / 0.8 none 2.2 10.3 21.0 Comparative Example 4 0.5 / 0.8 none 3.2 18.0 18.0 Comparative Example 5 0.6 / 0.9 none 2.8 10.5 22.5 Comparative Example 6 0.5 / 0.8 none 2.9 13.0 21.0 Comparative Example 7 0.5 / 0.8 none 3.2 10.0 24.2 Comparative Example 8 1.0 / 1.2 slight 1.6 12.5 17.5

[0181] Table 1-2 Detection Data of Examples and Comparative Examples

[0182] Sample number Layered integrity (%) Yellowing resistance index Bubble rate (%) Dimensional accuracy (±mm) Gloss (GU) Example 1 99.8 1.2 0.5 0.03 90.0 Example 2 99.5 1.3 0.8 0.03 88.5 Example 3 99.9 1.1 0.4 0.03 91.2 Example 4 99.9 1.2 0.3 0.02 90.5 Comparative Example 1 99.7 1.5 0.6 0.03 89.8 Comparative Example 2 99.6 1.2 0.7 0.03 80.2 Comparative Example 3 99.7 1.3 0.5 0.03 89.5 Comparative Example 4 0.0 1.2 0.6 0.04 90.1 Comparative Example 5 99.5 1.3 8.0 0.04 88.8 Comparative Example 6 99.8 1.2 0.7 0.05 89.2 Comparative Example 7 99.4 5.8 0.5 0.03 89.7 Comparative Example 8 90.0 1.4 5.0 0.05 75.0

[0183] From Table 1-1 and Table 1-2, we can see that:

[0184] (1) In Comparative Example 1, using ordinary uncoated pigments, obvious color migration was observed at the boundary between the two colors, with the color difference ΔE increasing from 0.5 to 1.8 for the first pigment and from 0.8 to 2.2 for the second pigment. In contrast, Examples 1-4, using isolated pigments, showed no color migration. This is because the polyurethane coating can physically lock the pigment molecules, blocking diffusion even at high vulcanization temperatures of 95-105℃, thus solving the problem of existing technologies' inability to control molecular-level color migration through physical isolation. If ordinary pigments are used instead, the refinement of the two-color appearance is significantly reduced, failing to meet the requirements of high-end sports shoes for clear boundary details.

[0185] (2) In Comparative Example 2, which was not subjected to plasma treatment, the interfacial peel strength decreased from 3.2 MPa in Example 1 to 2.0 MPa, and the simply supported beam impact strength decreased from 24.0 kJ / m. 2 Reduced to 20.0 kJ / m 2 The surface gloss also decreased from 90.0 GU to 80.2 GU. Data shows that plasma treatment can increase the number of active groups on the CPU surface, reducing the surface roughness Ra to 0.8-1.2 μm, and significantly enhancing the physical bonding with the GCU. Without this treatment, the two-color interface is prone to delamination under high-intensity motion, failing to meet dynamic stress requirements.

[0186] (3) In Comparative Example 3 without the addition of silane coupling agent, the interfacial peel strength decreased from 3.2 MPa to 2.2 MPa, and the impact strength decreased from 24.0 kJ / m. 2 Reduced to 21.0 kJ / m 2 The epoxy groups of the silane coupling agent react with the -OH groups on the CPU surface, while the siloxane groups crosslink with the -NCO groups of the GCU, forming a dual binding mechanism of physical interlocking and chemical bonding, overcoming the limitations of the single binding mode in existing technologies. Without this reagent, interfacial bonding relies solely on physical action, and the peel strength cannot reach the high-end standard of ≥3.0MPa.

[0187] (4) In Comparative Example 4 without the addition of hard lamellar layers, the Taber wear rate increased from 10.0 mg to 18.0 mg, and the simply supported beam impact strength increased from 24.0 kJ / m. 2 Reduced to 18.0 kJ / m 2 Furthermore, it lacks a layered structure. This composite layer, together with the GCU elastomer matrix, forms a shell-like layered structure. The hard phase resists frictional impact, while the soft phase absorbs kinetic energy, breaking the industry paradox that improved wear resistance necessarily reduces shock absorption. Without this structure, the wear resistance of the sole would be significantly reduced, failing to meet the long-term use requirements of athletic shoes.

[0188] (5) Comparative Example 5 used a single casting process, and the product bubble rate increased from 0.5% to 8.0%, while the interfacial peel strength decreased from 3.2 MPa to 2.8 MPa. Step-by-step casting can avoid the liquid material directly impacting the CPU preform, reduce interfacial bubble residue, and ensure uniform interfacial bonding. Existing technologies mostly use single filling, which easily leads to an increased defect rate due to bubbles. Therefore, this process feature is crucial for the economic efficiency of mass production.

[0189] (6) In Comparative Example 6, which was not subjected to constant temperature and humidity settling, the integrity of the layered structure decreased from 99.8% to 85.0%, the Taber wear increased from 10.0 mg to 13.0 mg, and the dimensional accuracy deteriorated from ±0.03 mm to ±0.05 mm. The settling process allows the GCU matrix to fully crosslink, stabilizes the position of the hard lamellars, and prevents the layered structure from becoming loose or deformed. Without this step, the product performance fluctuates greatly, and the pass rate decreases.

[0190] (7) Comparative Example 7, without the addition of anti-yellowing agent, showed an increase in yellowing resistance index from 1.2 to 5.8, far exceeding the requirement of ΔYI≤2.0 for high-end products. The first pigment uses high-gloss CPU, which is susceptible to yellowing due to ultraviolet radiation. Anti-yellowing agent can effectively delay this process and ensure the long-term appearance and texture of the product. Without this ingredient, the product is prone to yellowing and aging after use, failing to meet the demands of the high-end market.

[0191] (8) Comparative Example 8 did not use an isolating pigment paste, and trace amounts of carrier may remain after the TPU film melts, leading to slight diffusion of pigment molecules. Therefore, the color difference is higher than that of Example 1, and slight migration occurs at the boundary between the two colors, verifying the core advantage of the present invention over the physical isolation of the TPU film. After eliminating the plasma treatment and silane coupling agent, Comparative Example 8 relies solely on the physical adhesion of the TPU film through hot melting. The peel strength drops sharply from 3.2 MPa to 1.6 MPa, far below the requirement of ≥3.0 MPa for high-end sports shoes, directly exposing the defect of weak bonding at the interface of existing adhesive-free joints. The Taber abrasion of Comparative Example 8 increases from 10.0 mg to 12.5 mg: the residue from the melted TPU film may disrupt the directional arrangement of the hard layers, weakening the wear-resistant synergistic effect of the shell-like structure; and the simply supported beam impact strength decreases from 24.0 kJ / m 2 Reduced to 17.5 kJ / m 2Weak interfacial bonding prevents effective transfer of impact loads, easily leading to stress concentration at the interface and a significant decrease in impact resistance. In Comparative Example 8, the bubble rate increased from 0.5% to 5.0%. Trace amounts of gas are easily generated during the TPU film's heat-melting process, and the poor surface wettability without plasma treatment makes it difficult for the gas to escape. Furthermore, the dimensional accuracy deteriorated from ±0.03mm to ±0.05mm: fluctuations in TPU film thickness caused positioning deviations, and uneven interfacial thermal shrinkage further amplified dimensional errors. In Comparative Example 8, the first colorant was changed from high-gloss CPU to GCU material, and TPU film residue affected surface smoothness, resulting in a decrease in gloss from 90.0GU to 75.0GU, failing to meet the aesthetic requirements of high-end products.

[0192] In summary, the core technical features of this application, such as the isolation-type color paste, plasma treatment, silane coupling agent, composite rigid sheet, step-by-step casting, constant temperature and humidity settling, and anti-yellowing agent, solve core industry pain points such as color migration, weak interface bonding, the contradiction between wear resistance and shock absorption, and insufficient dimensional accuracy through chemical modification, structural biomimicry, and precise process control. The absence or replacement of any of these features will lead to a significant decline in product performance, failing to meet the comprehensive requirements of high-end sports shoes for high interface bonding strength, precise two-color effects, excellent functional performance, and aesthetic texture.

[0193] The present invention has been described by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A two-color molding process for shoemaking, characterized in that: Includes the following steps: S1. Prepare the first colorant and the second colorant respectively, wherein... The first colorant comprises the following raw materials in parts by weight: 100 parts of castable polyurethane elastomer; 2-4 parts of isolating colorant; and 0.2-0.3 parts of anti-yellowing agent; The second colorant comprises the following raw materials in parts by weight: 100 parts polytetrahydrofuran glycol; 25-30 parts diphenylmethane diisocyanate; 5-10 parts 1,4-butanediol; 8-12 parts mica flakes; 4-8 parts nano-alumina; 2.5-4 parts inorganic color paste; 0.5-1 part silane coupling agent; 0.2-0.8 parts dispersant; 0.1-0.5 parts antioxidant; and 1.5-3 parts toughening agent. S2. Inject the first colorant into a mold and then perform plasma treatment; S3. Place the plasma-treated first colorant product into the shoe sole mold and position it precisely; then inject the second colorant into the shoe sole mold, and after heat preservation vulcanization and cooling, demold to form a two-color shoe sole. S4. Trim and clean the two-tone soles to obtain the final two-tone sole product.

2. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S1, the preparation of the first colorant includes the following steps: (1) Weigh out the cast polyurethane elastomer and place it in a mixing device for stirring; (2) Add the isolating color paste and anti-yellowing agent to the mixing equipment according to the specified ratio; (3) Control parameters: temperature 75-85℃, speed 150-250rpm, stirring for 10-20min to obtain the first colorant.

3. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S1, the preparation of the second colorant includes the following steps: (1) Weigh out polytetrahydrofurandiol, diphenylmethane diisocyanate and 1,4-butanediol according to the proportion, mix them at 60-80℃ for 15-25 min to obtain GCU elastomer matrix, and put it into an extruder; (2) Weigh out mica sheets and nano-alumina, mix them, and dry them at 110-130℃ for 1-3 hours; then add 0.2% of the total amount of mica sheets and nano-alumina as silane coupling agent, mix them evenly, and obtain a hard sheet layer; (3) Introduce the GCU elastomer matrix into the melting section of the extruder and control the temperature at 190-200℃. After the GCU elastomer matrix melts, add the hard sheet, dispersant, inorganic color paste, remaining silane coupling agent, antioxidant and toughening agent. (4) Control the extrusion temperature: 175±3℃ for the feeding section, 195±5℃ for the melting section, and 200±3℃ for the die head section; the screw speed is 250-350rpm, the granulation particle size is 3-5mm, and the second colorant granules are obtained. (5) Dry the second colorant particles at 100-110℃ for 3.5-4.5h, and the moisture content of the particles is ≤0.08% to obtain the second colorant.

4. The two-color molding process for shoemaking according to claim 1, characterized in that: The specific steps of step S2 are as follows: (1) Use a mold that matches the target shape of the first colorant and preheat it to 55-65℃; (2) Inject the first colorant into the mold, control the injection temperature to 90-95℃, the injection pressure to 48-55MPa, the injection speed to 25-35mm / s, the holding pressure to 35-45MPa, and the holding time to 8-12s; (3) Use a chiller to control the temperature and cool the medium at 20°C. Cool to 40±2°C and then demold. (4) Place the first pigment product into the plasma treatment machine, control parameters: power 480-520W, treatment time 25-35s.

5. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S3, the shoe sole mold is first preheated to 80-90℃, and then the first colorant product after plasma treatment is placed in it; And / or, the positioning accuracy of the precise positioning is ±0.02mm.

6. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S3, when the second colorant is injected into the shoe sole mold, the pouring temperature is controlled at 95±3℃, the pouring pressure is 0.2-0.4MPa, and the pouring speed is 40-60mL / s; And / or, use step-by-step pouring, first fill 1 / 3 of the shoe sole mold cavity, pause for 1-3 seconds, and then fill to the full.

7. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S3, the heat preservation vulcanization treatment is as follows: heat preservation vulcanization at 95-105℃ for 25-35 min, and then cooling down to 80±3℃ at a cooling rate of 2-3℃ / min in the later stage of vulcanization. And / or, the cooling is: first cooling to 60±2℃ at a rate of 3℃ / min, and then cooling to 50±2℃ at a rate of 2℃ / min.

8. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S3, after demolding, the sole is placed in a constant temperature and humidity environment of 20-25℃ and 45%-55%RH for 20-30 hours to stabilize the shell-like layered structure.

9. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S4, trimming involves removing excess material from the edge of the sole with a trimming accuracy of ±0.1mm. The trimming direction should be consistent with the layered arrangement direction to avoid damaging the main layered structure.

10. The two-color molding process for shoemaking according to claim 1, characterized in that: In step S4, cleaning is performed by wiping the surface of the shoe sole with anhydrous ethanol to remove residual release agent; after cleaning, the sole is allowed to air dry naturally.

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