Color-changing elastomer-based composite foamed material, method for its preparation and use

Abstract

The application provides a color-changing composite foaming material based on expandable elastomer, a preparation method and application thereof. The color-changing composite foaming material is prepared from a photosensitive composite material through mixing and foaming. The photosensitive composite material comprises the following components in parts by mass: 20-40 parts of polyolefin elastomer; 15-35 parts of ethylene-vinyl acetate copolymer; 15-35 parts of olefin block copolymer; 5-18 parts of operating oil modified SEBS; 1.5-3 parts of silica gel; 0.2-1.5 parts of zinc oxide; 0.1-0.8 parts of stearic acid; 1-8 parts of photosensitive auxiliary agent, wherein the photosensitive auxiliary agent comprises a spiropyran compound; 0.3-8 parts of crosslinking agent; and 1.5-3.8 parts of foaming agent. The color-changing composite foaming material has excellent shock absorption performance, good resilience, high wear resistance, and can change color under light, thereby improving the strong three-dimensional appearance visual effect of the product.

Description

Technical Field

[0001] This invention relates to the field of foam materials technology, and in particular to a color-changing composite foam material based on expandable elastomer, its preparation method, and its application in sports shoe soles. Background Technology

[0002] Currently, the most commonly used material for athletic shoe soles is the ethylene vinyl acetate copolymer (EVA) cross-linked foam system. However, existing sole materials focus solely on properties such as lightweight, high resilience, compression resistance, and shock absorption, while the product's appearance relies on simple painting processes. As market demands for footwear become increasingly diverse, the external appearance of existing sole materials struggles to meet the demand for unique and visually appealing products. Summary of the Invention

[0003] In view of this, this application provides a color-changing composite foam material based on expandable elastomer, its preparation method and application. The color-changing composite foam material provided by this invention not only has excellent shoe sole properties, but also can change color in light and has a three-dimensional visual appearance.

[0004] This invention provides a color-changing composite foam material based on expandable elastomer, which is obtained by mixing and foaming a photosensitive composite material. The photosensitive composite material comprises the following components in parts by weight:

[0005] 20-40 parts of polyolefin elastomer;

[0006] 15-35 parts of ethylene-vinyl acetate copolymer;

[0007] 15-35 parts of olefin block copolymer;

[0008] 5-18 parts of processing oil modified SEBS;

[0009] 1.5 to 3 parts silicone;

[0010] 0.2 to 1.5 parts of zinc oxide;

[0011] 0.1 to 0.8 parts of stearic acid;

[0012] 1 to 8 parts of a photosensitizing agent, wherein the photosensitizing agent includes spiropyran compounds;

[0013] 0.3 to 8 parts of crosslinking agent;

[0014] 1.5 to 3.8 parts of foaming agent.

[0015] Preferably, the melt index of the polyolefin elastomer is 1-3 g / 10 min; the ultimate tensile strength of the olefin block copolymer is ≥13 MPa; and the VA content in the ethylene-vinyl acetate copolymer is 21-33%.

[0016] Preferably, the silicone is a heat-cured methyl silicone rubber.

[0017] Preferably, the zinc oxide is nano-active zinc oxide.

[0018] Preferably, the foaming agent is a transparent foaming agent.

[0019] Preferably, the crosslinking agent is an odorless crosslinking agent; the photosensitive composite material further includes 0.1 to 0.3 parts of a crosslinking aid.

[0020] Preferably, the specific gravity of the color-changing composite foam material is less than 0.28 g / cm³. 3 The surface has a finely textured effect.

[0021] This invention provides a method for preparing the color-changing composite foam material as described above, comprising the following steps:

[0022] S1. Polyolefin elastomer, ethylene vinyl acetate copolymer, olefin block copolymer and processing oil modified SEBS are mixed to obtain a preliminary mixture; silicone, zinc oxide, stearic acid, crosslinking agent, photosensitizing agent and foaming agent are mixed to obtain a photosensitizing material.

[0023] S2. The photosensitive material is mixed with the initial mixed material to obtain the remixed material;

[0024] S3. The remixed materials are granulated and foamed sequentially to obtain a color-changing composite foam material.

[0025] Preferably, the mixing in step S2 is carried out by twin-screw extrusion; the foaming temperature is 175-180℃.

[0026] This invention provides the application of the color-changing composite foam material as described above in the soles of sports shoes.

[0027] The color-changing composite foam material provided by this invention is obtained by mixing and foaming a photosensitive composite material. The photosensitive composite material forms a basic foaming system with a certain proportion of ethylene-vinyl acetate copolymer, polyolefin elastomer, olefin block copolymer, and SEBS modified with processing oil. This invention mainly introduces spiropyran-based photosensitive additives and uses a certain amount of silicone, stearic acid, zinc oxide, and other components to obtain a photosensitive color-changing composite foam material. While maintaining the material's abrasion resistance, resilience, and other shoe sole properties, the formulation of this invention not only crosslinks to form photosensitive molecular bonds, producing color changes according to light, but also forms fine particles similar to hemp seeds on the product surface, providing anti-slip properties. Therefore, the color-changing composite foam material of this invention has excellent shock absorption performance, good resilience, high abrasion resistance, and photosensitive color-changing properties, enhancing the product's strong three-dimensional visual appearance. Attached Figure Description

[0028] Figure 1 These are actual images of the shoe sole material obtained in Example 1 before and after photosensitive exposure. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a color-changing composite foam material based on expandable elastomer, which is obtained by mixing and foaming a photosensitive composite material. The photosensitive composite material comprises the following components in parts by weight:

[0031] 20-40 parts of polyolefin elastomer;

[0032] 15-35 parts of ethylene-vinyl acetate copolymer;

[0033] 15-35 parts of olefin block copolymer;

[0034] 5-18 parts of processing oil modified SEBS;

[0035] 1.5 to 3 parts silicone;

[0036] 0.2 to 1.5 parts of zinc oxide;

[0037] 0.1 to 0.8 parts of stearic acid;

[0038] 1 to 8 parts of a photosensitizing agent, wherein the photosensitizing agent includes spiropyran compounds;

[0039] 0.3 to 8 parts of crosslinking agent;

[0040] 1.5 to 3.8 parts of foaming agent.

[0041] To address the issue of monotonous appearance in traditional foam materials used in sports shoes, this invention provides a photosensitive color-changing composite foam material with excellent sole properties and a three-dimensional visual appearance, thus meeting diverse needs for footwear.

[0042] The color-changing composite foam material provided in this embodiment of the invention is obtained by mixing and foaming a photosensitive composite material. The photosensitive composite material, by weight, includes: 20-40 parts of polyolefin elastomer; 15-35 parts of ethylene vinyl acetate copolymer; and 15-35 parts of olefin block copolymer.

[0043] Ethylene-vinyl acetate copolymer (EVA) is a thermoplastic resin obtained by copolymerizing ethylene and vinyl acetate (VA). This material possesses excellent resilience, tensile strength, high toughness, aging resistance, ozone resistance, shock absorption, and cushioning properties. Adding ethylene-vinyl acetate copolymer to the formulation of this invention, preferably in parts by weight of 25-34, can adjust the compression recovery, resilience, shock absorption, and other comprehensive properties of the color-changing composite foam material. Specifically, in the embodiments of this application, the VA content in the EVA can be 21%-33% by weight. In some embodiments of this invention, the technical parameters of the ethylene-vinyl acetate copolymer include: VA 21-33% (VA content preferably 26%), specific gravity ≤0.948 g / cm³. 3 The embrittlement temperature is < -70℃, the ultimate tensile strength is > 14MPa, and the ultimate elongation is > 800%; the melt index is 2.5 g / 10min, the melting point is 80℃, and the hardness is 80°A. Preferably, the ethylene-vinyl acetate copolymer is one or more of the following: Formosa Plastics' EVA7470M, Dow Chemical's EVA460, EVA40L-03, and EVA40W.

[0044] Polyolefin elastomers are high-performance thermoplastic polyolefin products that exhibit rubber-like elasticity at room temperature, possessing characteristics such as low density, high flexural strength, high low-temperature impact resistance, and ease of processing. The preferred dosage of the polyolefin elastomer is 30-35 parts by weight. In the composite material formulation of this invention, it provides excellent resilience and compression resistance, resulting in composite foam materials with high resilience and compression resistance. In specific embodiments of this application, the technical parameters of the polyolefin elastomer include: melt index 1-3 g / 10 min; hardness 60-75°A; glass transition temperature -55℃ to -30℃; melting point 47℃ to 90℃; ultimate tensile strength 6-22 MPa; and ultimate elongation > 600%. Preferably, the polyolefin elastomer is one or more of the following from Dow Chemical Company: Engage8180, Engage8003, Engage8450, Engage7467, and BER6000.

[0045] Olefin block copolymers (OBCs) are molecular chains consisting of alternating blocks of hard and soft segments. OBCs exhibit flexibility, heat resistance, good compression set, and processability. Unique cyclic catalysis technology allows for the modification and control of block lengths, resulting in lower stress relaxation compared to other polymers. Lower stress relaxation indicates higher grip, which is crucial for the anti-slip performance of products. These OBCs also exhibit better abrasion resistance than random ethylene copolymers of similar density. When used in the composite material formulation of this invention, they impart excellent abrasion resistance, anti-slip properties, shock absorption, resilience, resistance to compression deformation, and fatigue resistance. In particular, they help maintain the resilience, compressibility, and overall physical properties of shoes during athletic activities, even when the heat generated by flexing affects the sole's elasticity.

[0046] The composite material of this invention preferably comprises 16-30 parts of an olefin block copolymer. In a specific embodiment of this application, the technical parameters of the olefin block copolymer (OBC) are as follows: melt index 0.5 g / 10min, hardness 60-65°A, glass transition temperature -60℃ to -55℃, compressibility at 21℃ 16-20%, compressibility at 70℃ 40-50%, ultimate tensile strength ≥13MPa, and ultimate elongation >600%. Preferably, the commercially available olefin block copolymer is one or more of OBC9107, OBC9007, OBC9500, and OBC9077 manufactured by Dow Chemical Company.

[0047] Furthermore, the basic foaming system in this embodiment of the invention includes 5 to 18 parts of processing oil-modified SEBS, preferably 10 to 17 parts by weight. SEBS is a linear triblock copolymer with polystyrene as the end block and ethylene-butene copolymer obtained by hydrogenation of polybutadiene as the middle elastic block. SEBS does not contain unsaturated double bonds in its structure and has excellent aging resistance, possessing both plasticity and high elasticity. When the processing oil-modified SEBS is applied to the blend system of this invention, the crystallinity of the polyolefin elastomer, olefin block copolymer, and ethylene vinyl acetate copolymer remains unchanged, and the melting temperature of the blend decreases significantly. Due to the increased miscibility of the blend melt in the molten state, the crystallization of the polymer, the blocks, and the processing oil form a homogeneous melt system. It is precisely because the blend can dissolve in the block polymer melt containing amorphous structures that an interpenetrating network (IPN) structure is formed. When added to the formulation of the composite material of this invention, under certain process conditions, fine particles similar to hemp seeds appear on the surface of the product, which improves the anti-slip performance of the material and enhances the visual appearance, greatly improving the resilience, anti-slip performance, and overall performance of the material.

[0048] The aforementioned oil-modified SEBS, also known as oil-extended SEBS, specifically has a linear structure, a rubber / styrene ratio of 69 / 31 (mass percentage), and a melt flow index of 10 g / 10 min. Preferably, the oil-modified SEBS is one or more of the following types: 7550, 7551, and 9557D, manufactured by Lee Chang Yung Co., Ltd. in Taiwan.

[0049] In this invention, the photosensitive composite material comprises 1-8 parts by weight of a photosensitive auxiliary agent, preferably 1.1-5 parts. The photosensitive auxiliary agent of this invention comprises spiropyran compounds, and commercially available photosensitive color-changing powder products of this type are acceptable. Spiropyran compounds possess photochromic properties; when these compounds contain hydroxyl, carboxyl, and amino groups in their structure, they exhibit reverse photochromic properties. Under illumination, these compounds form new ions due to different wavelengths of ultraviolet light, causing changes in their conjugation degree, thus displaying different colors. The principle of photochromism can be seen in the following reaction formula:

[0050] .

[0051] This invention adds the aforementioned photosensitive additive to the composite material, creating photosensitive molecular bonds that possess photosensitivity. Sunlight exposure opens these bonds in the shoe sole, allowing the composite material to absorb sunlight energy and transition from a low energy level to a high energy level—from invisible light to visible light—resulting in a color change. When sunlight exposure ceases, the photosensitive molecular bonds close, returning the material to its original color. Therefore, the composite material of this invention can change color according to the intensity of light, sensing the degree of harm sunlight poses to the human body. For example, it can alert people in summer whether they need to wear sun protection clothing, thus endowing the product of this invention with special health benefits.

[0052] In this embodiment of the invention, if the amount of photosensitive additive is too small, the photosensitive color-changing effect is poor, which is not conducive to application. Furthermore, during the mixing in a mixer, granulation in a screw granulator, or extrusion using a syringe, the intense shear force can easily damage the molecules of the photosensitive material, reducing or eliminating its photosensitive color-changing properties. Therefore, in this embodiment of the invention, stearic acid is used to perform surface activation treatment on the photosensitive material before it is mixed with silica gel.

[0053] According to the mass fractions, the photosensitive composite material of this invention comprises: 1.5-3 parts of silicone rubber; and 0.1-0.8 parts of stearic acid. The amount of stearic acid is preferably 0.3-0.5 parts; the silicone rubber is preferably a heat-curing methyl silicone rubber, and commercially available products are acceptable. Specifically, the silicone rubber used is 110-methyl vinyl silicone rubber, whose main structure includes siloxane, vinyl groups, and silica; wherein the vinyl content is 0.14 wt%, the volatile matter is 0.94 wt%, and the molecular weight is 630,000. In the silicone rubber structure of this invention, the siloxane produces a fine-particle feel on the material's appearance, the vinyl group improves the anti-slip effect, and carbon dioxide, etc., improves the material's wear resistance.

[0054] Furthermore, the photosensitive composite material described in this embodiment of the invention includes 0.2 to 1.5 parts of zinc oxide (ZnO). Preferably, the zinc oxide is nano-active zinc oxide, which can be a commercially available product, wherein the ZnO purity is ≥95% and the specific surface area is ≥45m². 2 / g. In the embodiments of the present invention, the nano-active zinc oxide is a novel multifunctional inorganic material, characterized by its nano-sized particles, possessing the dual properties of both nanomaterials and traditional zinc oxide. Compared with traditional zinc oxide products, it has a larger specific surface area, higher chemical activity, and exhibits photochemical effects and better UV shielding performance. Furthermore, it possesses a series of unique properties such as antibacterial, bacteriostatic, deodorizing, and enzyme-inhibiting effects. In the embodiments of the present invention, a small amount of nano-active zinc oxide can be added to the formulation of the composite foam material to reduce the specific gravity of the composite material, giving the composite foam material multiple functions such as lightweight, antibacterial, and deodorizing properties.

[0055] This invention uses 0.3-8 parts of a crosslinking agent and 1.5-3.8 parts of a foaming agent, which are mixed and foamed to prepare the above-mentioned color-changing composite foam material. Preferably, the foaming agent is a transparent foaming agent. In a preferred embodiment of this invention, the transparent foaming agent is a transparent, odorless white powder, added to the above formula to form pores. The volume after foaming is several times or even more than ten times the original volume, increasing the product's transparency and achieving a light transmittance ≥30%, resulting in a better appearance. Preferably, the crosslinking agent is an odorless crosslinking agent (or odorless crosslinking agent), such as Akzo's Perkadox 14S-F1 odorless crosslinking agent. In embodiments of this invention, the photosensitive composite material also includes 0.1-0.3 parts of a crosslinking aid, which can be TAIC (trimethylene diisocyanate), facilitating crosslinking and foaming.

[0056] In an embodiment of the present invention, the specific gravity of the color-changing composite foam material is 0.25 ± 0.03 g / cm³. 3The surface has a fine granular effect. Furthermore, embodiments of the present invention provide the application of the aforementioned color-changing composite foam material in the soles of athletic shoes. The athletic shoe soles manufactured using this technical solution possess an appearance effect unmatched by ordinary plastic foam formulations, as well as excellent resilience, shrinkage resistance, abrasion resistance, wrinkle resistance, and comfort, greatly satisfying people's demands for athletic performance, fashion performance, and health benefits in athletic shoes.

[0057] Accordingly, the present invention also provides a method for preparing the color-changing composite foam material as described above, comprising the following steps:

[0058] S1. Polyolefin elastomer, ethylene vinyl acetate copolymer, olefin block copolymer and processing oil modified SEBS are mixed to obtain a preliminary mixture; silicone, zinc oxide, stearic acid, crosslinking agent, photosensitizing agent and foaming agent are mixed to obtain a photosensitizing material.

[0059] S2. The photosensitive material is mixed with the initial mixed material to obtain the remixed material;

[0060] S3. The remixed materials are granulated and foamed sequentially to obtain a color-changing composite foam material.

[0061] In this embodiment of the invention, the following components are weighed according to their mass percentages: 20-40 PHR of polyolefin elastomer, 15-35 PHR of ethylene-vinyl acetate copolymer, 15-35 PHR of olefin block copolymer, and 5-18 PHR of oil-extended SEBS. These weighed components are then placed in a mixing apparatus for mixing. The mixing apparatus can be a liner machine, which is well-known in the art. The preferred mixing time is 8-10 minutes, and the temperature is 110-115°C, to obtain a preliminary mixture.

[0062] Furthermore, in this embodiment of the invention, the following components are weighed in parts by weight: 1.5-3 PHR of silica gel, 0.2-1.5 PHR of zinc oxide, 0.3-0.5 PHR of stearic acid, 0.25-0.75 PHR of crosslinking aid, 0.3-8 PHR of odorless crosslinking agent, 1-8 PHR of photosensitizing agent, and 1.5-3.8 PHR of transparent foaming agent. These weighed components are then mixed to obtain a photosensitizing material.

[0063] Then, in this embodiment of the invention, the obtained photosensitive material is added to the pre-mixed material and mixed using a twin-screw extruder for 5-7 minutes at a temperature of 115-118°C to obtain a remixed material.

[0064] In this embodiment of the invention, the mixture obtained from the second mixing is placed in a granulator for granulation. The granulation time is 9-11 minutes, and the temperature is 110℃-120℃. The granulated mixture is then foamed. Two foaming methods are used, one of which is secondary molecular weighting (MD), requiring small-scale foaming. The preferred foaming time is 350-380 seconds, and the foaming temperature is 175℃-180℃, resulting in a color-changing composite foam material.

[0065] According to the composite foam material and its preparation method described above, the composite foam material of this invention can be selected with different formulation combinations to meet the requirements of different products. The production process of this color-changing composite material is simple. It only requires loading various components into a mixing machine in sequence for mixing. The time is short and the operating conditions are suitable. The resulting composite material has excellent heat shrinkage resistance, high elasticity, and pressure resistance. After the obtained material is granulated and cooled, it can be directly molded through small-scale foaming and then oven-set to obtain the finished shoe sole. Alternatively, the same effect can be obtained by adjusting the technical parameters of an IP foam molding machine.

[0066] To further understand this application, the following detailed description, in conjunction with embodiments, illustrates the color-changing composite foam material based on expandable elastomers, its preparation method, and its application. However, it should be understood that these embodiments are implemented based on the technical solution of this invention, providing detailed implementation methods and specific operating procedures, and are only intended to further illustrate the features and advantages of this invention, not to limit the scope of the claims of this invention. The protection scope of this invention is not limited to the following embodiments.

[0067] Example 1

[0068] Using the formulation components in Table 1, weigh the following components by mass parts: polyolefin elastomer, ethylene-vinyl acetate copolymer, olefin block copolymer, and oil-extended SEBS. Place these weighed components in a liner mixer and mix for 8-10 minutes at a temperature of 110-115℃ to obtain a preliminary mixture. Weigh the following components by mass parts: silica gel, zinc oxide, stearic acid, crosslinking aid, odorless crosslinking agent, photosensitizing agent, and transparent foaming agent. Mix these weighed components to obtain a photosensitizing material.

[0069] The obtained photosensitive material is added to the pre-mixed material and then mixed using a twin-screw extruder for 5-7 minutes at a temperature of 115-118℃ to obtain the remixed material.

[0070] The mixture obtained from the second mixing is placed in a granulator for granulation at a time of 9-11 minutes and a temperature of 110℃-120℃. The granulated mixture is then foamed using a secondary MD method, requiring small-scale foaming for 350-380 seconds at a temperature of 175℃-180℃, to obtain a color-changing composite foam material for shoe soles.

[0071] See the image below for the effect of the obtained foamed sole material before photosensitive treatment. Figure 1 Left side, Figure 1 The image on the right shows the effect after it has been exposed to light (using natural sunlight, it changes color in 4 seconds); Figure 1 The bottom of the one on the right looks relatively worse (the color change is not obvious).

[0072] Example 2

[0073] Using the formulation components in Table 1 and the method of Example 1, a color-changing composite foam material was prepared to obtain the material.

[0074] Comparative Examples 1-3

[0075] Composite foam materials were prepared using the formulation components listed in Table 1 and the method described in Example 1.

[0076] Table 1: Blending Formulations (parts by weight) of Composite Foaming Materials in Embodiments of the Invention

[0077]

[0078] In Table 1, the polyolefin elastomer was POE Engage 8003 from Dow Chemical Company, USA; the ethylene-vinyl acetate copolymer was EVA 7470M from Formosa Plastics Corporation; the olefin block copolymer was OBC 9107 from Dow Chemical Company, USA; and the oil-extended SEBS was product 901 (purchased from Xiamen Boshiyuan Company, with the following composition: Formosa Plastics 7470M: 20 Phr, Dow POE 8150: 30 Phr, Baling Petrochemical SEBS 503T: 25 Phr, and naphthenic oil 4006: 25 Phr). In the comparative examples, the SEBS was product 7551 from Lee Chang Yung Chemical Co., Ltd. (Taiwan), the EVA wear-resistant agent was 108E produced by Xiamen Boshiyuan, and the odorless crosslinking agent was Perkadox from AkzoNobel. Product 14S-F1; the photosensitive additive is spiropyran-based photochromic powder, model OP-108 (Tianjin Fuxin Sunshine Technology Co., Ltd.); the silicone is 110-methyl vinyl silicone rubber (vinyl content 0.16mol, produced by Zhejiang Hesheng Silicon Industry Co., Ltd.); the zinc oxide is nano-active zinc oxide; the crosslinking agent is TAIC; the transparent foaming agent is TS100 from Jinjiang Jinlang Company.

[0079] The foamed materials obtained in Examples 1-2 and the comparative example were subjected to shoe sole performance tests, and the results are as follows:

[0080] Table 2: Properties of composite foamed materials obtained in Examples 1-2 and Comparative Examples 1-3

[0081]

[0082] Note: If the light change effect is not obvious to the eye, then the light change effect is poor.

[0083] Hardness, elongation at break, and tensile strength are all results from two tests.

[0084] All of the above were obtained according to national standard methods.

[0085] As shown in Table 2, the color-changing composite foam material prepared by this invention possesses unique visual appeal and health benefits, and offers lasting comfort and cushioning. The product exhibits a strong three-dimensional visual appearance, giving the impression of magical color-changing properties. This invention provides a functional foam material for athletic shoe soles that is wear-resistant, shock-absorbing, and protects health—a product unmatched by existing products, filling a gap in the athletic shoe market.

[0086] The above provides a detailed description of the energy-concentrating photochromic composite foam material for sports shoe soles and its preparation method. Specific examples have been used to illustrate the embodiments of the present invention. The descriptions of the above embodiments are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements, modifications, and product appearances also fall within the protection scope of the claims of the present invention.

Claims

1. A color-changing composite foam material based on expandable elastomer, characterized in that, The photosensitive composite material is prepared by mixing and foaming, and the photosensitive composite material comprises the following components in parts by weight: 20-40 parts of polyolefin elastomer; 15-35 parts of ethylene-vinyl acetate copolymer; 15-35 parts of olefin block copolymer; 5-18 parts of processing oil modified SEBS; 1.5 to 3 parts silicone; 0.2 to 1.5 parts of zinc oxide; 0.1 to 0.8 parts of stearic acid; 1 to 8 parts of a photosensitizing agent, wherein the photosensitizing agent includes spiropyran compounds; 0.3 to 8 parts of crosslinking agent; 1.5 to 3.8 parts of a foaming agent, wherein the foaming agent is a transparent foaming agent; The melt index of the polyolefin elastomer is 1-3 g / 10 min; the ultimate tensile strength of the olefin block copolymer is ≥13 MPa; the VA content in the ethylene-vinyl acetate copolymer is 21-33%; the zinc oxide is nano-active zinc oxide; the silica gel is heat-cured methyl silicone rubber; the crosslinking agent is an odorless crosslinking agent; the photosensitive composite material also includes 0.1-0.3 parts of crosslinking aid. The foaming temperature is 175-180℃; the specific gravity of the color-changing composite foam material is less than 0.28 g / cm³. 3 The surface has a finely textured effect.

2. The preparation method of the color-changing composite foam material as described in claim 1, comprising the following steps: S1. Polyolefin elastomer, ethylene vinyl acetate copolymer, olefin block copolymer and processing oil modified SEBS are mixed to obtain a preliminary mixture; silicone, zinc oxide, stearic acid, crosslinking agent, photosensitizing agent and foaming agent are mixed to obtain a photosensitizing material. S2. The photosensitive material is mixed with the initial mixed material to obtain the remixed material; S3. The remixed material is granulated and foamed sequentially at a temperature of 175-180℃ to obtain a color-changing composite foamed material.

3. The preparation method according to claim 2, characterized in that, In step S2, the mixing is carried out using a twin-screw extrusion method.

4. The application of the color-changing composite foam material as described in claim 1 in the sole of sports shoes.

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