Supercritical foaming material and composite insole

Abstract

The invention provides a supercritical foaming material and a composite insole, and relates to the technical field of foaming materials. The supercritical foaming material is prepared from a raw material component comprising the following components (i)-(iii) through a supercritical foaming process: the component (i) is a thermoplastic polyester elastomer, the component (ii) is a polyester / polysiloxane copolymer, and the component (iii) is an auxiliary agent. Preferably, the weight of the polyester / polysiloxane copolymer is 5-20% of the weight of the thermoplastic polyester elastomer. The polyester / polysiloxane copolymer is added into the TPEE, so that not only can the performance of the supercritical foaming TPEE be improved, but also the peel strength with a film layer can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of foaming and relates to a supercritical foaming material and a composite shoe midsole. Background Art

[0002] Supercritical foaming materials have been widely used in many application fields, such as soles, cushioning materials, and thermal insulation materials, due to their low density, good resilience, and low thermal conductivity. Many polymer materials are suitable for supercritical foaming processes and are used to prepare supercritical foaming materials, such as EVA, TPU, and polyester materials. Although supercritical foaming materials have been successfully used in many applications, there are still some shortcomings. For example, taking the supercritical foaming material used as the midsole of a shoe as an example, there are problems of easy dirtiness and insufficient wear resistance. Chinese patent CN118772600A discloses a highly wear-resistant TPEE supercritical foaming material, which improves the wear resistance of TPEE by adding SEBS-g-MAH and modified calcium sulfate. In addition, the industry is also continuing to improve and perfect supercritical foaming materials and related technologies to further improve their performance, such as mechanical strength and resilience. Summary of the invention

[0003] In order to improve the problems of easy dirtiness and insufficient wear resistance of supercritical foaming materials as midsoles, the present application laminates and coats a layer of film on the supercritical foaming material, which is not only more beautiful, but also improves the dirt resistance and wear resistance of the shoe material. It is also found that adding a certain amount of polyester-modified polysiloxane material to the supercritical foaming polyester material can effectively improve the performance of the supercritical foaming material and the laminating and coating effect of the film layer. Based on this, the present invention proposes a supercritical foaming material and a composite midsole.

[0004] The technical solution of the present invention is as follows:

[0005] A supercritical foaming material is obtained by a supercritical foaming process from raw material components comprising the following components (i) to (iii);

[0006] Component (i) a thermoplastic polyester elastomer;

[0007] Component (ii) polyester / polysiloxane copolymer;

[0008] and, component (iii) an auxiliary agent.

[0009] Preferably, the polyester / polysiloxane copolymer is selected from at least one of a polyester / polysiloxane random copolymer and a polyester / polysiloxane block copolymer.

[0010] More preferably, the polyester / polysiloxane random copolymer is selected from polysiloxane side chain grafted polyester.

[0011] More preferably, the polyester / polysiloxane block copolymer is an AB structure, an ABA structure, a BAB structure or an (AB) n At least one of the structures, wherein A represents polyester and B represents polysiloxane.

[0012] Preferably, the weight of the polyester / polysiloxane copolymer is not less than 5% and not more than 20% relative to the weight of the polyester material.

[0013] Preferably, the auxiliary agent is selected from at least one of an anti-yellowing agent, an anti-ultraviolet agent, a heat-resistant additive and a flame retardant.

[0014] Preferably, the raw material components further include component (iv) polyester polyurethane.

[0015] More preferably, the weight of the polyester polyurethane is 0.5-3% relative to the weight of the polyester material.

[0016] A composite shoe midsole comprises the supercritical foaming material described in any one of the above embodiments and a film layer covering the supercritical foaming material.

[0017] Preferably, the film layer is made of polyurethane or polyurea.

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention adds a certain amount of polyester / polysiloxane copolymer to the supercritical foaming polyester material. It is found that when the amount of the polyester / polysiloxane copolymer exceeds a certain ratio, in addition to improving the resilience of the foaming material, the lamination and coating effect of the film layer can also be improved.

[0020] (2) It was found that the mechanical strength of the supercritical foamed polyester can be further improved by further adding polyester polyurethane to the supercritical foamed polyester material of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0022] In order to improve the performance of a supercritical foaming material, the present invention provides a supercritical foaming material, which is obtained by a supercritical foaming process through a raw material component comprising the following components (i) to (iii);

[0023] Component (i) a thermoplastic polyester elastomer;

[0024] Component (ii) polyester / polysiloxane copolymer;

[0025] and, component (iii) an auxiliary agent.

[0026] Thermoplastic polyester elastomer TPEE has both the excellent elasticity of rubber and the easy processing of thermoplastics, and has high strength, good flexibility and good dynamic mechanical properties. Supercritical foamed TPEE has good resilience, and the ball rebound can reach more than 70%, but the tensile strength and tear strength are lower than those of supercritical foamed TPU. The present invention finds that adding polyester / polysiloxane copolymer to TPEE can further improve the mechanical properties of TPEE supercritical foaming materials, such as tensile strength and tear strength. One of the possible reasons is that polyester / polysiloxane copolymer can play a role in improving the uniformity of foaming when TPEE is foamed. In the present invention, there is no special restriction on the source of TPEE, and it can be directly obtained from the market, such as DuPont, KOLON of South Korea, etc.

[0027] In some embodiments, the polyester / polysiloxane copolymer is selected from at least one of a polyester / polysiloxane random copolymer and a polyester / polysiloxane block copolymer. The polyester segment in the polyester / polysiloxane copolymer has good compatibility with TPEE, while the polysiloxane segment has poor compatibility with TPEE, and the surface tension of the polysiloxane segment is low, so that the polyester / polysiloxane copolymer has the characteristics of amphiphilicity in TPEE and has the function of a foaming agent, which can further improve the penetration and swelling uniformity of the supercritical fluid into TPEE and improve the foaming uniformity.

[0028] In the present invention, the polysiloxane segment is not particularly limited, and can be a polydimethylsiloxane segment, a polymethylvinylsiloxane segment, a polymethylphenylsiloxane segment (such as a phenyl content of 5-20 mol%), a polymethyltrifluoropropylsiloxane segment, or a combination of the above segments, such as a combination of a polydimethylsiloxane segment and a polymethyltrifluoropropylsiloxane segment. It is generally believed that the addition of a polymer containing polysiloxane will reduce the surface energy of the material due to the low surface tension of the polysiloxane, resulting in a decrease in the bonding strength with other materials. The present invention unexpectedly found that the addition of a polyester / polysiloxane copolymer to TPEE can improve the peel strength of the supercritical foaming TPEE to the film layer, which may be related to the polyester / polysiloxane copolymer increasing the surface roughness of the supercritical foaming TPEE. More preferably, the polysiloxane segment is a combination of a polydimethylsiloxane segment and a polymethyltrifluoropropylsiloxane segment (generally referred to as polyfluorosiloxane). The polyfluorosiloxane containing the methyltrifluoropropylsiloxane segment has a better adhesion effect on the film layer (such as TPU, polyurea, etc.) and a higher peel strength. This may be related to the fact that the polyfluorosilicone is more likely to migrate to the surface of the supercritical foaming TPEE and form a greater roughness. For example, the structure of polyfluorosilicone can be -Me2SiO(SiOMe2) a (SiOMeR f ) b SiMe2-, R fis 3,3,3-trifluoropropyl, Me is methyl, a>0, b>0, or 0.25a≤b≤0.6a.

[0029] In some embodiments, the polyester / polysiloxane random copolymer is selected from polysiloxane side chain grafted polyester. The polysiloxane side chain grafted polyester can be obtained by a hydrosilylation reaction between a hydrogen-containing polysiloxane and a terminal olefinic polyester, or by other methods, such as a reaction between a side chain chloroalkyl polysiloxane and a carboxylate salt of a polyester, or a reaction between a terminal isocyanate polyester and a polysiloxane containing an amino group (such as a secondary amino group) in the side chain, or a ring-opening reaction between a side chain hydroxyalkyl polysiloxane and caprolactone.

[0030] In some embodiments, the polyester / polysiloxane block copolymer is an AB structure, an ABA structure, a BAB structure or an (AB) n At least one of the structures, wherein A represents polyester and B represents polysiloxane. Taking the ABA structure as an example, it can be obtained by a silylation reaction between a terminal olefin polyester and a biterminal silane polysiloxane, or by a condensation reaction between a terminal hydroxyalkyl polysiloxane and a terminal carboxyl polyester, or by a ring-opening reaction between a terminal epoxy polysiloxane and a terminal hydroxyl polyester.

[0031] For example, the polysiloxane side chain grafted polyester and the polyester / polysiloxane block copolymer can be obtained by respectively carrying out a hydrosilylation reaction between a hydrogen-containing polysiloxane and a terminal olefinic polyester. The terminal group of the terminal olefinic polyester can be a hydroxyl group, a methyl group, an acetyl group, etc., and the weight average molecular weight can be 200-4000, or further, the weight average molecular weight can be 400-1000. The terminal olefinic polyester can be obtained by carrying out a ring-opening reaction between an olefinic alcohol (such as 1-allyl alcohol, 1-butylene alcohol, 1-hexenol, hydroxyethyl acrylate, etc.) and a cyclic lactone (such as caprolactone, 4-butyrolactone, etc.). For example, the structure of the terminal olefinic polyester can be CH2=CH(CH2) m O[CO(CH2) n O] x R1 or CH2=CHCOO(CH2) c O[CO(CH2) d O] yR2, wherein m=1-4, n=3-5, x=2-10, c=2-4, d=3-5, y=2-10, R1 and R2 are independently selected from H, C1-C4 alkyl or C2-C4 acyl. To obtain the polysiloxane side chain grafted polyester, the silicon hydride group of the hydrogen-containing polysiloxane used is located on the side chain (generally referred to as side hydrogen polysiloxane or side hydrogen silicone oil), and to obtain the polysiloxane block copolymer, the silicon hydride group of the hydrogen-containing polysiloxane used is located on the terminal group (generally referred to as terminal hydrogen polysiloxane or terminal hydrogen silicone oil), which is well known to those skilled in the art. For example, the structure of the side hydrogen polysiloxane or side hydrogen silicone oil can be Me3SiO(SiOMe2) e (SiOMeH) f SiMe3, where e>0, f>0. The side hydrogen polysiloxane is characterized by viscosity and hydrogen content, for example, the viscosity at 25°C can be 10-500 mPa.s, and the hydrogen content can be 0.1-1.0 wt%. For terminal hydrogen polysiloxane or terminal hydrogen silicone oil, for example, the structure can be HMe2SiO(SiOMe2) g SiMe2H, wherein 10≤g≤300, the hydrogen-terminated polysiloxane is characterized by viscosity, for example, the viscosity at 25°C may be 30-300 mPa.s.

[0032] In the present invention, it is found that the effect of the polysiloxane side chain grafted polyester is better than that of the polyester / polysiloxane block copolymer. This may be because the polysiloxane side chain grafted polyester has a comb-like structure, and the polyester chain segment is located in the side chain, which has a higher degree of freedom than the polyester chain segment located in the main chain in the polysiloxane block copolymer. Moreover, the comb-like structure of the polysiloxane side chain grafted polyester can form more mutual entanglement with the polymer chain of TPEE.

[0033] In some embodiments, the weight of the polyester / polysiloxane copolymer is not less than 5% and not more than 20% relative to the weight of the polyester material. In the present invention, the weight proportion of the polyester / polysiloxane copolymer is within the above range. In addition to playing the role of amphiphilicity, a part of the polyester / polysiloxane copolymer can be precipitated onto the surface of the supercritical foaming TPEE to play the role of polysiloxane in generating static electricity, so that the supercritical foaming material can be more easily bonded and coated by means of static electricity. Moreover, since the polyester / polysiloxane copolymer is a macromolecule, the roughness of the PTFE surface may be increased after precipitation onto the surface of the supercritical foaming TPEE, and the bonding strength after operations such as hot pressing is higher. For example, the weight of the polyester / polysiloxane copolymer relative to the weight of the polyester material can be any value of 5%, 6%, 7%, 8%, 9%, 10%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc., without special restrictions. Further, the weight of the polyester / polysiloxane copolymer relative to the weight of the polyester material can be 6-15%.

[0034] In some embodiments, the auxiliary agent is selected from at least one of an anti-yellowing agent, an anti-ultraviolet agent, a heat-resistant additive and a flame retardant. The anti-yellowing agent can be an anti-yellowing agent commonly used in the field of rubber or plastics, such as DM series anti-yellowing agents, antioxidant 1010, etc., and the dosage can be 0.1-0.5% of the weight of TPEE; the anti-ultraviolet agent can be an anti-ultraviolet agent commonly used in the field of rubber or plastics, such as UV-327, UV-328, UV-326, UV-P, etc., and the dosage can be 0.1-0.5% of the weight of TPEE. The heat-resistant additive can be a heat-resistant additive commonly used in the field of rubber or plastics, such as cerium oxide, iron oxide, etc., and the dosage can be 0.5-3% of the weight of TPEE. The flame retardant can be a flame retardant commonly used in the field of rubber or plastics, such as a phosphorus-containing flame retardant, and the dosage can be 1-5% of the weight of TPEE.

[0035] In some embodiments, the raw material components further include component (iv) polyester polyurethane. The polyester segment in the polyester polyurethane has good compatibility with TPEE, while the carbamate structure with high polarity and high hardness has poor compatibility with TPEE. The polyester polyurethane will agglomerate and / or aggregate in TPEE due to surface tension (similar to the formation of micelle structure by surfactant in water), and the carbamate structure of the hard segment aggregates inward and can form local physical crosslinks in the foaming material due to the formation of a large number of hydrogen bonds, which can better resist the force of external stress and improve the mechanical strength of the supercritical foaming material. In the present invention, the polyester polyurethane is not particularly limited and can be a thermoplastic polyurethane elastomer TPU, such as conventional polyester type (such as butanediol adipate) TPU, polycarbonate type TPU and polycaprolactone type TPU.

[0036] The present invention finds that the amount of polyester polyurethane added cannot be too much, otherwise it may cause some properties of the supercritical foaming material to be significantly reduced, which may be related to the limited compatibility between polyester polyurethane and TPEE. In some embodiments, the weight of the polyester polyurethane is 0.5-3% relative to the weight of the polyester material. For example, the weight of the polyester polyurethane relative to the weight of the polyester material can be any value of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc., without special restrictions. Further, the weight of the polyester polyurethane relative to the weight of the polyester material can be 1-2.5%.

[0037] In the present invention, the supercritical foaming process has no particular limitation, for example, the material to be foamed is placed in a pressure-resistant container, fully infiltrated, permeated and swelled by a supercritical fluid (such as supercritical CO2, supercritical nitrogen, supercritical methane, etc.), and then the pressure is quickly released to achieve microporous foaming. After microporous foaming, water vapor heating or other heating methods can be further used for shaping.

[0038] In order to improve the wear resistance and stain resistance of the supercritical foamed shoe midsole, on the other hand, the present invention also provides a composite shoe midsole, comprising the supercritical foamed material described in any of the above embodiments and a film layer coating the supercritical foamed material. In the present invention, the method of coating the supercritical foamed material with a film layer is adopted to solve the shortcomings of the supercritical foamed material being not wear-resistant and easy to stain.

[0039] In some embodiments, the material of the film layer is polyurethane or polyurea. Polyurethane and polyurea have the characteristics of good wear resistance and good anti-fouling performance. For the coating method, polyurethane film material (such as TPU hot melt film or TPU waterproof breathable film, etc.) or polyurea film material can be directly used for film coating, or polyurethane coating or polyurea coating can be sprayed into film. In order to improve the aesthetics of the midsole of the shoe, the supercritical foaming material and the film layer in the present invention can be natural color or colorful.

[0040] The technical solution of the present invention is further described and illustrated according to various embodiments below. Unless otherwise specified, the parts described in the following embodiments are parts by weight.

[0041] Example 1

[0042] The supercritical foaming material consists of 100 parts of TPEE, 6 parts of polyester / polysiloxane copolymer and 0.2 parts of antioxidant 1010 and is added into a twin-screw extruder for mixing, uniform melting and extrusion molding.

[0043] The polyester / polysiloxane copolymer is a polysiloxane side chain grafted polyester, which is prepared as follows: side hydrogen silicone oil (viscosity 180mPa.s at 25°C, hydrogen content 0.55wt%) and terminal olefin polyester CH2=CHCOO(CH2)2O[CO(CH2)4O] 8.2 CH3 was added into the reactor at a molar ratio of Si-H to olefin group of 1:1.02, the temperature was raised to 90°C, Karstedt catalyst (20 ppm based on Pt) was added, the temperature was controlled at 130-135°C for 4 hours, the pressure was reduced to below -0.099 MPa to remove low boiling products, the temperature was lowered to obtain polysiloxane side-chain grafted polyester.

[0044] The supercritical foaming process is as follows: add the above-mentioned supercritical foaming material into an autoclave, introduce supercritical CO2 fluid, the foaming temperature is 90°C, the foaming pressure is 20MPa, the foaming time is 3h, and then the pressure is quickly released, and then placed in a constant temperature device at 110°C for 20 minutes to obtain a supercritical foaming material.

[0045] Example 2

[0046] The difference between this embodiment and embodiment 1 is that in embodiment 1, the polyester / polysiloxane copolymer is adjusted from 6 parts to 2 parts. The other steps remain unchanged.

[0047] Example 3

[0048] The difference between this embodiment and embodiment 1 is that in embodiment 1, the polyester / polysiloxane copolymer is adjusted from 6 parts to 15 parts. The other steps remain unchanged.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that in embodiment 1, the polyester / polysiloxane copolymer is adjusted from 6 parts to 25 parts. The other steps remain unchanged.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that in Example 1, no polyester / polysiloxane copolymer is added. The other steps remain unchanged.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 1 is that in Example 1, the polyester / polysiloxane copolymer is replaced by an equal weight of a polyurethane foam leveler (DC193 from Dow Corning). The other steps remain unchanged.

[0055] Example 5

[0056] The supercritical foaming material consists of 100 parts of TPEE, 10 parts of polyester / polysiloxane copolymer, 0.2 parts of antioxidant 1010 and 0.3 parts of UV-328 and is added to a twin-screw extruder for mixing, melting evenly and extrusion molding, and then foamed according to the supercritical foaming process of Example 1.

[0057] The polyester / polysiloxane copolymer is a polysiloxane side chain grafted polyester, which is prepared as follows: side hydrogen silicone oil (viscosity 340mPa.s at 25°C, hydrogen content 0.42wt%) and terminal olefin polyester CH2=CHCOO(CH2)2O[CO(CH2)4O] 6.3 CH3 was added into the reactor at a molar ratio of Si-H to olefin group of 1:1.02, the temperature was raised to 90°C, Karstedt catalyst (20 ppm based on Pt) was added, the temperature was controlled at 130-135°C for 4 hours, the pressure was reduced to below -0.099 MPa to remove low boiling products, the temperature was lowered to obtain polysiloxane side-chain grafted polyester.

[0058] Example 6

[0059] The difference between this embodiment and embodiment 5 is that in embodiment 5, the side hydrogen silicone oil is adjusted to the side hydrogen fluoro silicone oil of equal weight, the side hydrogen fluoro silicone oil has a viscosity of 590 mPa.s at 25° C., a hydrogen content of 0.45 wt%, and a methyl trifluoropropyl siloxane segment accounting for 55%. The remaining steps remain unchanged.

[0060] Example 7

[0061] The difference between this embodiment and embodiment 5 is that in embodiment 5, the polyester / polysiloxane copolymer is adjusted to a polyester-polysiloxane block copolymer of equal weight. The other steps remain unchanged.

[0062] The preparation method of the polyester-polysiloxane block copolymer is as follows: hydrogen-terminated silicone oil (viscosity 280 mPa.s at 25°C) and the terminal olefin polyester in Example 5 are added to a reaction kettle at a Si-H to olefin molar ratio of 1:1.01, the temperature is raised to 90°C, a Karstedt catalyst is added (based on the amount of Pt, the amount added is 20 ppm), the temperature is controlled at 135-140°C, the reaction is carried out for 4 hours, the pressure is reduced to below -0.099 MPa to remove low boiling products, the temperature is lowered, and a polyester-polysiloxane block copolymer is obtained.

[0063] Example 8

[0064] The difference between this embodiment and embodiment 5 is that in embodiment 5, the raw material components of the supercritical foaming material further include 1 part of polycaprolactone type TPU. The other steps remain unchanged.

[0065] Example 9

[0066] The difference between this embodiment and embodiment 8 is that in embodiment 8, the polycaprolactone TPU is adjusted from 1 part to 2.5 parts. The other steps remain unchanged.

[0067] Example 10

[0068] The difference between this embodiment and embodiment 8 is that in embodiment 8, the polycaprolactone TPU is adjusted from 1 part to 4 parts. The other steps remain unchanged.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 8 is that in Example 8, no polyester / polysiloxane copolymer is added. The other steps remain unchanged.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 8 is that in Example 8, the polycaprolactone TPU is replaced by an equal weight of polyether TPU. The other steps remain unchanged.

[0073] The performance test results of the supercritical foam material are shown in Table 1. The density is tested according to ISO 845:2006; the tensile strength is tested according to ISO 1798:2008; the tear strength (trouser type) is tested according to ISO 8068:2008; and the ball rebound resilience is tested according to ASTM D3574.

[0074] Table 1

[0075] <![CDATA[Density / g / cm 3 > Tensile strength / MPa Tear strength / KN / m Ball rebound / % Example 1 0.117 3.3 40 73 Example 2 0.121 3.0 35 70 Example 3 0.110 3.7 42 72 Example 4 0.118 3.1 37 69 Comparative Example 1 0.127 2.8 34 70 Comparative Example 2 0.142 2.5 30 65 Example 5 0.112 3.6 42 72 Example 6 0.122 3.3 39 70 Example 7 0.115 3.2 37 70 Example 8 0.113 3.8 44 72 Example 9 0.116 4.3 47 70 Example 10 0.120 3.3 40 67 Comparative Example 3 0.131 3.0 31 66 Comparative Example 4 0.136 2.5 30 62

[0076] From the data in Table 1 above, it can be seen that the addition of polyester / polysiloxane copolymer to TPEE in the present invention can improve the mechanical strength of supercritical foamed TPEE and is also beneficial to the resilience. The continued addition of polyester polyurethane can further improve the performance of supercritical foamed TPEE.

[0077] The supercritical foaming materials of Examples 1, 2, 5, 6 and 8 and Comparative Example 1 were cut into sizes of 10 cm × 10 cm × 1 cm, and TPU hot melt adhesive films were attached to their surfaces at a laminating temperature of 120°C and a pressure of 0.2 MPa. After being placed at room temperature for 48 hours, the peel strength was tested according to the method of GB / T 2792-2014. The peel strength retention rate after immersion in 50°C water for 48 hours was also tested. The results are shown in Table 2 below.

[0078] Table 2

[0079]

[0080] Therefore, according to the data in Table 2, the supercritical foamed TPEE of the present invention has a high peel strength and good water resistance after being laminated and hot-pressed with the TPU film layer. When the amount of polyester / polysiloxane in the supercritical foamed TPEE is low, the peel strength will be reduced.

[0081] As described above, the basic principles, main features and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited by the above embodiments, which are only preferred embodiments of the present invention and cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the scope of the present invention and the contents of the specification should still be within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A supercritical foaming material, characterized in that: The method is obtained by subjecting the raw material components comprising the following components (i) to (iii) to a supercritical foaming process; Component (i) a thermoplastic polyester elastomer; Component (ii) polyester / polysiloxane copolymer; and, component (iii) an auxiliary agent.

2. The supercritical foaming material according to claim 1, characterized in that: The polyester / polysiloxane copolymer is selected from at least one of a polyester / polysiloxane random copolymer and a polyester / polysiloxane block copolymer.

3. The supercritical foaming material according to claim 2, characterized in that: The polyester / polysiloxane random copolymer is selected from polysiloxane side chain grafted polyesters.

4. The supercritical foaming material according to claim 2, characterized in that: The polyester / polysiloxane block copolymer is an AB structure, an ABA structure, a BAB structure or an (AB) n At least one of the structures, wherein A represents polyester and B represents polysiloxane.

5. The supercritical foaming material according to claim 1, characterized in that: The weight of the polyester / polysiloxane copolymer is not less than 5% and not more than 20% relative to the weight of the polyester material.

6. The supercritical foaming material according to claim 1, characterized in that: The auxiliary agent is selected from at least one of an anti-yellowing agent, an anti-ultraviolet agent, a heat-resistant additive and a flame retardant.

7. The supercritical foaming material according to claim 1, characterized in that: The raw material components further include component (iv) polyester polyurethane.

8. The supercritical foaming material according to claim 7, characterized in that: The weight of the polyester polyurethane is 0.5-3% relative to the weight of the polyester material.

9. A composite shoe midsole, characterized in that: The invention comprises the supercritical foaming material according to any one of claims 1 to 8 and a film layer coating the supercritical foaming material.

10. The composite shoe midsole according to claim 9, characterized in that: The material of the film layer is polyurethane or polyurea.

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