TPEE foaming material and preparation method thereof

Abstract

The invention provides a TPEE foaming material and a preparation method thereof. The TPEE foaming material comprises a TPEE matrix, filler particles and holes between the TPEE matrix and the filler particles. The volume ratio of the holes is 18-35%, and the distribution uniformity U of filler particles is greater than or equal to 85%. The TPEE foaming material is prepared from the following raw materials in parts by weight: 70 to 90 parts of thermoplastic polyester elastomer, 1 to 5 parts of foaming agent, 2 to 15 parts of filler and 0 to 10 parts of additive. The foaming agent is a composite foaming agent with a core-shell structure, a shell layer of the composite foaming agent with the core-shell structure has hydrophilicity, and the filler is a plastic filler with hydrophilicity. The TPEE foaming material has the advantages of good foaming performance, high porosity, high strength and good rebound resilience, can realize rapid rebound, and is especially suitable for shoe materials.

Description

Technical Field

[0001] The present invention relates to the technical field of material processing, in particular to a shoe material, and more particularly to a TPEE foaming material and a preparation method thereof. Background Art

[0002] TPEE (thermoplastic polyester elastomer) is a block copolymer containing polyester hard segment and polyether soft segment. The polyether soft segment and the uncrystallized polyester form an amorphous phase, and the polyester hard segment partially crystallizes to form a crystalline micro-region, which acts as a physical cross-linking point. TPEE has the elasticity of rubber and the strength of engineering plastics. The soft segment gives it elasticity, making it like rubber; the hard segment gives it processing properties, making it like plastic. Compared with rubber, it has better processing properties and longer service life; compared with engineering materials, it also has the characteristics of high strength, but better flexibility and dynamic mechanical properties.

[0003] The special properties of TPEE materials are currently widely used in the electronics, communications and automotive industries, and are replacing rubber products in more and more fields. Shoe materials are an important field where TPEE materials replace rubber products. TPEE materials have good elasticity, tensile strength and fatigue resistance, and can be used as outsoles and midsoles of shoes. In order to improve the application of TPEE materials in shoe materials, the industry currently makes them into TPEE foam materials to improve wearing comfort by reducing weight. However, the current TPEE foam materials have the following problems: if the pores of TPEE foam materials are too small, it is difficult to reduce weight, and if the porosity is too large, the strength is not high. The shoes made from them are easy to deform and not durable, and the rebound ability is poor, making it difficult to achieve rapid rebound. Summary of the invention

[0004] Based on the above problems, the purpose of the present invention is to provide a TPEE foam material and a preparation method thereof. The TPEE foam material has good foaming performance, not only has a high porosity but also has high strength, and has good resilience and can achieve rapid rebound, and is particularly suitable for use in shoe materials.

[0005] To achieve the above-mentioned purpose, on one hand, the present invention provides a TPEE foam material, comprising a TPEE matrix, filler particles and holes between the TPEE matrix and the filler particles, wherein the volume proportion of the holes is 18-35%, the distribution uniformity of the filler particles is U, U≥85%, and the preparation raw materials include 70-90 parts of thermoplastic polyester elastomer, 1-5 parts of foaming agent, 2-15 parts of filler and 0-10 parts of auxiliary agent in parts by weight, the foaming agent is a composite foaming agent with a core-shell structure, the shell layer of the composite foaming agent with a core-shell structure is hydrophilic, and the filler is a hydrophilic plastic filler.

[0006] In the technical solution adopted by the present invention, the foaming agent is a composite foaming agent with a hydrophilic core-shell structure, and the filler is a hydrophilic plastic filler. Both the composite foaming agent and the plastic filler are hydrophilic. During the preparation process, the surface of the hydrophilic large-particle plastic filler will adsorb the hydrophilic composite foaming agent, and after foaming, holes are formed between the TPEE matrix and the filler particles. The volume proportion of the holes is 18-35%. Its high proportion can not only reduce weight, but also the TPEE foaming material can be deformed by external force and transfer the external force to the plastic filler. The reaction force of the plastic filler with a distribution uniformity of more than 85% can make the TPEE foaming material rebound quickly, and the hydrophilic plastic filler can also maintain the strength of the TPEE foaming material during long-term use to avoid deformation. Therefore, the present invention can not only maintain the TPEE foaming material with better foaming performance through special foaming agents and special fillers, but also maintain better strength and rapid rebound performance.

[0007] As a technical solution of the present invention, the melting point of the thermoplastic polyester elastomer is 140-170°C, the Shore hardness of the thermoplastic polyester elastomer is 30-60D, and the density of the thermoplastic polyester elastomer is 1.10-1.39 g / cm 3 .

[0008] As a technical solution of the present invention, the thermoplastic polyester elastomer can be obtained by polymerizing butylene terephthalate, polyether polyol and polyester polyol and introducing dimethyl isophthalate.

[0009] As a technical solution of the present invention, the foaming agent is a sodium bicarbonate composite foaming agent, and the particle size of the foaming agent is 25 to 150 μm.

[0010] As a technical solution of the present invention, the foaming agent includes sodium bicarbonate particles, an epoxy resin layer, and an organic acid modified layer from the inside to the outside.

[0011] As a technical solution of the present invention, the material of the organic acid modified layer includes citric acid, palmitic acid or stearic acid.

[0012] As a technical solution of the present invention, the filler is plastic particles grafted with maleic acid or acrylic acid, the melting point of the filler is 220-280° C., and the particle size of the filler is 0.5-3.0 mm.

[0013] As a technical solution of the present invention, the plastic particles include at least one of epoxy resin particles, polycarbonate particles and polytetrafluoroethylene particles.

[0014] As a technical solution of the present invention, the auxiliary agent includes at least one of a heat stabilizer, an anti-ultraviolet absorber and a lubricant.

[0015] The second aspect of the present invention provides a method for preparing the TPEE foam material, comprising the steps of:

[0016] (1) Spray granulation

[0017] The foaming agent and the filler are mixed in a solvent and dispersed to obtain a suspension, and the suspension is spray-dried to obtain a foaming filler composition;

[0018] (2) Premix

[0019] Preliminarily melt-mixing the thermoplastic polyester elastomer and the auxiliary agent in a twin-screw extruder to obtain a primary mixture;

[0020] (3) Injection molding

[0021] The foaming filler composition is added into the primary mixture and mixed before injection molding.

[0022] In the preparation method of the TPEE foam material of the present invention, a hydrophilic plastic filler and a hydrophilic composite foaming agent are uniformly dispersed and granulated in a dispersion process to obtain a plurality of aggregates of the composite foaming agent wrapped plastic filler. The thermoplastic polyester elastomer is premixed into a liquid homogeneous system and then added to the aggregate, and the aggregate can be uniformly dispersed in the liquid homogeneous system. The high temperature during injection molding can make the foaming agent foam to form a TPEE foam material with uniform holes, and the plastic filler and the thermoplastic polyester elastomer in the foam material are separated by holes, so that when the manufactured product is subjected to an external force applied to the plastic filler, the reaction force generated by the plastic filler can make the TPEE foam material rebound quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the partial structure of the TPEE foam material of the present invention. DETAILED DESCRIPTION

[0024] The TPEE foam material of the present invention has high strength, a tensile strength of up to 15.7 MPa or more, good resilience, a rebound rate of up to 75% or more, and can achieve rapid rebound, and is particularly suitable for use as a shoe material.

[0025] In parts by weight, the raw materials for preparing the TPEE foam material of the present invention include 70 to 90 parts of thermoplastic polyester elastomer, 1 to 5 parts of foaming agent, 2 to 15 parts of filler and 0 to 10 parts of auxiliary agent.

[0026] The content of the thermoplastic polyester elastomer may be, but is not limited to, 70 parts, 72 parts, 74 parts, 76 parts, 78 parts, 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, and 90 parts. The melting point of the thermoplastic polyester elastomer is 140 to 170° C., and its melting point may be, but is not limited to, 140° C., 142° C., 144° C., 146° C., 148° C., 150° C., 152° C., 154° C., 156° C., 158° C., 160° C., 163° C., 165° C., 167° C., and 170° C. The thermoplastic polyester elastomer may be obtained by polymerization of butylene terephthalate, polyether polyol, and polyester polyol and introduction of dimethyl isophthalate. The polymerization process of thermoplastic polyester elastomer can adopt conventional polymerization method, that is, butylene terephthalate, dimethyl isophthalate and polyether polyol, polyester polyol are mixed and polymerized under the action of crosslinking agent. Polyester polyol and polyether polyol have good mutual solubility. In the copolymerization process, polyester polyol is easier to polymerize with butylene terephthalate to form an amorphous phase to form an ultra-soft soft segment, which relatively reduces the amount of hard segment, changes the crystallinity, and finally improves the crystallinity of TPEE to reduce its melting point. At the same time, adding dimethyl isophthalate will also change the crystallinity, thereby reducing the hardness and melting point of TPEE, so it can be made into a thermoplastic polyester elastomer with a melting point of only 140-170°C. The Shore hardness of thermoplastic polyester elastomer is 30-60D. As an example, the Shore hardness can be but not limited to 30D, 35D, 40D, 45D, 50D, 55D, 60D. The density of thermoplastic polyester elastomer is 1.10~1.39g / cm 3 As an example, the density may be, but is not limited to, 1.10 g / cm 3 , 1.12g / cm 3 , 1.14g / cm 3 , 1.16g / cm 3 , 1.18g / cm 3 , 1.20g / cm 3 , 1.23g / cm 3 , 1.26g / cm 3 , 1.29g / cm 3 , 1.31g / cm 3 , 1.33g / cm 3 , 1.35g / cm 3 , 1.37g / cm 3 , 1.39g / cm 3 .

[0027] The content of the foaming agent can be, but is not limited to, 1 part, 2 parts, 3 parts, 4 parts, and 5 parts. The foaming agent is a composite foaming agent of a core-shell structure, and the shell layer of the composite foaming agent of the core-shell structure is hydrophilic. The foaming agent includes sodium bicarbonate particles, an epoxy resin layer, and an organic acid modified layer from the inside to the outside, and the organic acid modified layer gives the shell layer of the foaming agent hydrophilicity. The decomposition temperature of sodium bicarbonate is low, and the decomposition temperature range is wide. It is too far away from the melting point of the thermoplastic polyester elastomer and cannot match the injection molding of the thermoplastic polyester elastomer. The decomposition temperature of sodium bicarbonate can be increased and the decomposition temperature range can be reduced by surface modification of epoxy resin. The use of organic acid for outer coating can further increase the decomposition temperature and enhance the strength of the coating layer. The decomposition temperature of the foaming agent can reach 155-170°C. The surface modification of epoxy resin and organic acid can form a barrier layer to change the solubility of sodium bicarbonate, and turn the easily soluble sodium bicarbonate into a water-insoluble composite foaming agent. Therefore, in the subsequent preparation process, it can only be dispersed with the filler in the aqueous solvent to obtain a suspension. The particle size of the foaming agent is 25-150μm. The shell layer of the foaming agent with a small particle size is hydrophilic and can be adsorbed on the surface of the large particle filler. The material of the organic acid modified layer includes citric acid, palmitic acid or stearic acid, which has better bonding with maleic acid or acrylic acid on the surface of the plastic particles, so it can form a uniform aggregate. The surface modification of sodium bicarbonate particles by epoxy resin can dissolve the epoxy resin in an organic solvent and then disperse it evenly with sodium bicarbonate. By adding additives such as curing agent and dispersant, a thin epoxy resin layer is formed on the surface of the sodium bicarbonate particles through the curing of the epoxy resin. The content of epoxy resin needs to be controlled, and its content should not be too high, otherwise the epoxy resin layer formed is too thick and the decomposition temperature is too high. If the temperature does not reach the decomposition temperature during the subsequent injection molding process, it is difficult to effectively foam, and the epoxy resin layer is too thick, and the gas generated by sodium bicarbonate foaming is difficult to escape and affect the foaming quality. The mass of epoxy resin and sodium bicarbonate is preferably 1:4-7. The modification of surface organic acid can dissolve the organic acid in an organic solvent, and then add the sodium bicarbonate particles modified by epoxy resin under acidic conditions. Some active groups on the epoxy resin react with the organic acid under heating conditions to modify the surface layer so that the surface layer has hydrophilicity. The modification of surface organic acid needs to control the pH value of the system. The acidity of the system should not be too high, otherwise the stronger the acidity, the more violent the reaction of the active groups of the organic acid and the epoxy resin, the thicker and denser the formed coating layer, the decomposition temperature is too high, and it is difficult for sodium bicarbonate to form effective foaming. Preferably, the pH value of the system is ≥3.

[0028] The content of the filler can be, but is not limited to, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, and 15 parts. The filler is a hydrophilic plastic filler. Further, the filler is a plastic particle grafted with maleic acid or acrylic acid. Maleic acid or acrylic acid is used for grafting. It is preferably combined with the organic acid on the composite foaming agent and can be evenly distributed in the thermoplastic polyester elastomer with the composite foaming agent. After the composite foaming agent is foamed, holes are formed around the filler. The plastic particles include at least one of epoxy resin particles, polycarbonate particles, and polytetrafluoroethylene particles. Such plastic particles have a high melting point. The melting point of the prepared filler is 220 to 280°C. As an example, the melting point can be, but is not limited to, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, and 280°C. The particle size of the filler is 0.5 to 3.0 mm. As an example, the particle size can be, but is not limited to, 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm. Maleic acid or acrylic acid is used to graft plastic particles, and conventional melt grafting, solution grafting, suspension grafting, radiation grafting, monomer direct copolymerization, supercritical CO2 method, and solid phase grafting can be used. The degree of maleic acid or acrylic acid grafting reaction should not be too large, otherwise it will significantly reduce the melting point of the plastic particles, causing them to melt during injection molding and unable to maintain their granular state. Preferably, in the grafting reaction, the mass ratio of maleic acid or acrylic acid to plastic particles is less than or equal to 8%, the mass ratio of initiator to plastic particles is less than or equal to 5%, and the grafting reaction time is less than or equal to 2 hours.

[0029] The content of the auxiliary agent can be, but is not limited to, 0 parts, 1 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts. The auxiliary agent includes at least one of a heat stabilizer, an anti-ultraviolet absorber, and a lubricant. The heat stabilizer is preferably a polyimide stabilizer to improve the thermal stability of the TPEE foaming material. The anti-ultraviolet absorber can be a hindered phenol antioxidant 3114, a hindered phenol antioxidant 1010, an ultraviolet absorber UV-5411, an antioxidant 168, an antioxidant 1076, or an antioxidant 164 to prevent the shoe material from being oxidized and discolored by light. The lubricant can be one of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, and methyl hydroxy silicone oil, and the lubricant can improve the surface smoothness of the shoe material to avoid roughness.

[0030] like Figure 1As shown, the TPEE foam material 100 includes a TPEE matrix 10, filler particles 30 and holes 50 between the TPEE matrix 10 and the filler particles 30. The TPEE matrix 10 is formed by injection molding of the aforementioned thermoplastic polyester elastomer and additives. The filler particles 30 are the aforementioned hydrophilic plastic fillers. The holes 50 are formed by foaming a composite foaming agent with a hydrophilic core-shell structure. The volume proportion of the holes is 18-35%. As an example, the volume proportion of the holes can be but not limited to 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%. The high proportion of holes can not only reduce weight, but also provide rebound space. The distribution uniformity of the filler particles is U, U≥85%, and the filler particles have a high distribution uniformity, so they can rebound quickly. The calculation formula and method of U can be shown as follows.

[0031] By analyzing the cross-sectional images of TPEE foam materials, n 150 mm × 80 mm areas were randomly selected from the obtained images, where n ≥ 10, and the number of fillers in each area was calculated as pi, where i was 1, 2, 3…n, and the average number of fillers in n areas was p, and the uniformity was U.

[0032]

[0033] The preparation method of the TPEE foam material of the present invention comprises the following steps.

[0034] (1) Spray granulation

[0035] The foaming agent and the filler are mixed in a solvent and dispersed to obtain a suspension, and the suspension is spray-dried to obtain a foaming filler composition.

[0036] (2) Premix

[0037] The thermoplastic polyester elastomer and the additive are preliminarily melt-mixed in a twin-screw extruder to obtain a preliminary mixture.

[0038] (3) Injection molding

[0039] The foaming filler composition is added to the primary mixture and mixed before injection molding.

[0040] Among them, the foaming agent and the filler can be mixed in water or in a mixed solution of water and an organic solvent, such as in water or in a mixed solution of water-ethanol. The foaming agent and the filler can be dispersed in the solvent by ultrasonic vibration, or dispersed in the solvent by adding a dispersant. The dispersant is an aqueous dispersant, such as sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, etc. The spray drying temperature is 80-110°C. The spray drying temperature should not be too high. It is only necessary to evaporate the solvent. Too high a spray drying temperature will affect the use of the foaming agent. The maximum temperature of injection molding is 160-185°C. The injection molding temperature should not be too high, otherwise the filler will melt and cannot be maintained in a granular state.

[0041] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0042] Example 1

[0043] (1) Preparation of thermoplastic polyester elastomer A1

[0044] Weigh 1.6 kg of butylene terephthalate, 0.2 kg of dimethyl isophthalate, 25.1 g of antioxidant 168 and 30 g of crosslinking agent trimethylolpropane into a polymerization kettle and mix well. React at 180°C for 60 min under nitrogen protection. Then add 1.0 kg of polyether polyol and 0.5 kg of polyester polyol. React at 280°C for 90 min under nitrogen protection to obtain thermoplastic polyester elastomer A1. The performance of thermoplastic polyester elastomer A1 was tested, with a melting point of 155°C, a Shore hardness of 48D, and a density of 1.23 g / cm 3 .

[0045] (2) Preparation of thermoplastic polyester elastomer A2

[0046] Weigh 1.6 kg of butylene terephthalate, 0.4 kg of dimethyl isophthalate, 25.1 g of antioxidant 168 and 30 g of crosslinking agent trimethylolpropane into a polymerization kettle and mix well. React at 185°C for 60 min under nitrogen protection. Then add 1.0 kg of polyether polyol and 0.6 kg of polyester polyol. React at 280°C for 120 min under nitrogen protection to obtain thermoplastic polyester elastomer A1. The performance of thermoplastic polyester elastomer A1 was tested, with a melting point of 145°C, a Shore hardness of 40D, and a density of 1.18 g / cm 3 .

[0047] Example 2

[0048] (1) Preparation of foaming agent B1

[0049] After drying the sodium bicarbonate, ball mill the sodium bicarbonate particles with a mesh size of 200. Dissolve 5g of epoxy resin in anhydrous ethanol and add 30g of sodium bicarbonate particles to make a suspension. Then add diethylenetriamine and sodium dodecyl sulfate, each accounting for 8% by mass of the system, stir evenly, heat to 75°C and react for 5h, wash and dry to obtain the sodium bicarbonate foaming agent coated with the epoxy resin layer.

[0050] Dissolve 1.0g of stearic acid in ethanol and add dilute hydrochloric acid to adjust the pH value to 4, add 0.8g of sodium bicarbonate foaming agent coated with epoxy resin layer, stir evenly, heat to 75℃ and react for 5h, wash and dry to obtain foaming agent B1. Foaming agent B1 includes sodium bicarbonate particles, epoxy resin layer and organic acid modified layer from inside to outside. The performance of foaming agent B1 was tested, and the particle size was 55-75μm and the decomposition temperature was 163℃.

[0051] (2) Preparation of foaming agent B2

[0052] After drying the sodium bicarbonate, ball mill the sodium bicarbonate particles with a mesh size of 200. Dissolve 5g of epoxy resin in anhydrous ethanol and add 35g of sodium bicarbonate particles to make a suspension. Then add diethylenetriamine and sodium dodecyl sulfate, each accounting for 7% by mass of the system, stir evenly, heat to 75°C and react for 5h, wash and dry to obtain the sodium bicarbonate foaming agent coated with the epoxy resin layer.

[0053] Dissolve 1.1g of citric acid in ethanol and add dilute hydrochloric acid to adjust the pH value to 4, add 1.0g of sodium bicarbonate foaming agent coated with epoxy resin layer, stir evenly, heat to 75℃ and react for 7h, wash and dry to obtain foaming agent B1. Foaming agent B1 includes sodium bicarbonate particles, epoxy resin layer and organic acid modified layer from inside to outside. The performance of foaming agent B2 was tested, and the particle size was 50-73μm and the decomposition temperature was 157℃.

[0054] (3) Preparation of foaming agent B3

[0055] After drying the sodium bicarbonate, ball mill and select 200-mesh sodium bicarbonate particles. Dissolve 5g of epoxy resin in anhydrous ethanol, and add 30g of sodium bicarbonate particles to make a suspension. Then add diethylenetriamine and sodium dodecyl sulfate, each accounting for 8% of the system mass, stir evenly, heat to 75°C and react for 5h, wash and dry to obtain foaming agent B3. Foaming agent B3 includes sodium bicarbonate particles and epoxy resin layers from the inside to the outside. The performance of foaming agent B3 was tested, and the particle size was 45-60μm and the decomposition temperature was 149°C.

[0056] (4) Preparation of foaming agent B4

[0057] After drying the sodium bicarbonate, ball mill the sodium bicarbonate particles with a mesh size of 200. Dissolve 1.0g of stearic acid in ethanol and add dilute hydrochloric acid to adjust the pH value to 4, add 1.5g of sodium bicarbonate particles, stir evenly, heat to 75°C and react for 5h, wash and dry to obtain foaming agent B4. Foaming agent B4 includes sodium bicarbonate particles and an organic acid modified layer from the inside to the outside. The performance of foaming agent B4 was tested, and the particle size was 38-50μm and the decomposition temperature was 130°C.

[0058] (5) Preparation of foaming agent B5

[0059] After drying the sodium bicarbonate, the sodium bicarbonate particles of 200 mesh were selected by ball milling to obtain the foaming agent B5. The performance of the foaming agent B5 was tested, and the particle size was 34-40 μm and the decomposition temperature was 119°C.

[0060] Example 3

[0061] (1) Preparation of filler C1

[0062] Epoxy resin particles, benzoyl peroxide (accounting for 2% of the mass of epoxy resin particles) and xylene (accounting for 4% of the mass of epoxy resin particles) were added to the reactor, and the temperature was raised to 130°C for preheating for 0.5h, and then maleic acid (accounting for 7% of the mass of epoxy resin particles) and benzoyl peroxide (accounting for 3% of the mass of epoxy resin particles) were added to continue the reaction for 2h, and then washed and dried to obtain filler C1. The performance of filler C1 was tested, and the particle size was 1.0-1.2mm and the melting point was 270°C.

[0063] (2) Preparation of filler C2

[0064] Polycarbonate particles, benzoyl peroxide (accounting for 1% of the mass of the polycarbonate particles) and xylene (accounting for 4% of the mass of the polycarbonate particles) were added to the reactor, and the temperature was raised to 130°C for preheating for 0.5h, and then maleic acid (accounting for 6% of the mass of the polycarbonate particles) and benzoyl peroxide (accounting for 3% of the mass of the polycarbonate particles) were added to continue the reaction for 3h, and then washed and dried to obtain filler C2. The performance of filler C2 was tested, and the particle size was 1.1-1.3mm and the melting point was 235°C.

[0065] (3) Preparation of filler C3

[0066] Add polytetrafluoroethylene particles, benzoyl peroxide (accounting for 2% of the mass of polytetrafluoroethylene particles) and xylene (accounting for 3% of the mass of polytetrafluoroethylene particles) into the reactor, heat to 130°C and preheat for 0.5h, then add maleic acid (accounting for 7% of the mass of polytetrafluoroethylene particles) and benzoyl peroxide (accounting for 3% of the mass of polytetrafluoroethylene particles) and continue to react for 2h, wash and dry to obtain filler C3. The performance of filler C3 is tested, and the particle size is 1.5-1.8mm and the melting point is 317°C.

[0067] (4) Preparation of filler C4

[0068] Epoxy resin particles were selected as filler C4. Performance testing of filler C4 showed that the particle size was 0.9-1.1 mm and the melting point was 278°C.

[0069] Example 4

[0070] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B1, 6 parts of filler C1, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0071] Example 5

[0072] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A2, 4 parts of foaming agent B1, 6 parts of filler C1, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0073] Example 6

[0074] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B2, 6 parts of filler C1, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0075] Example 7

[0076] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B1, 6 parts of filler C2, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0077] Example 8

[0078] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B1, 6 parts of filler C3, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0079] Example 9

[0080] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 75 parts of thermoplastic polyester elastomer A1, 5 parts of foaming agent B1, 8 parts of filler C1, 1 part of polyimide stabilizer, 4 parts of antioxidant 168 and 2 parts of ethyl silicone oil.

[0081] Example 10

[0082] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 85 parts of thermoplastic polyester elastomer A1, 5 parts of foaming agent B1, 5 parts of filler C1 and 2 parts of polyimide stabilizer.

[0083] Embodiment 11

[0084] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B3, 6 parts of filler C1, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0085] Example 12

[0086] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B4, 6 parts of filler C1, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0087] Example 13

[0088] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B5, 6 parts of filler C1, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0089] Embodiment 14

[0090] This embodiment is a TPEE foam material. In terms of weight, the raw materials for preparing the TPEE foam material include 80 parts of thermoplastic polyester elastomer A1, 4 parts of foaming agent B1, 6 parts of filler C4, 1 part of polyimide stabilizer, 2 parts of hindered phenol antioxidant 3114 and 1 part of methyl silicone oil.

[0091] The preparation method of the TPEE foam material of Examples 4 to 14 may include the following steps.

[0092] (1) Spray granulation

[0093] The foaming agent and filler are mixed in water according to the formula amount and dispersed to obtain a suspension, and the suspension is spray-dried at 100° C. to obtain a foaming filler composition.

[0094] (2) Premix

[0095] Preliminarily melt-mixing the thermoplastic polyester elastomer and the additive in a twin-screw extruder to obtain a primary mixture;

[0096] (3) Injection molding

[0097] The foaming filler composition was added to the initial mixture and then mixed and injection molding was performed at 170°C.

[0098] The TPEE foam materials prepared in Examples 4 to 14 were subjected to performance testing. The testing method is as follows. The test results are shown in Table 1.

[0099] (1) Volume ratio of holes

[0100] The specific surface area and porosity analyzer was used to analyze the volume ratio of pores.

[0101] (2) The distribution uniformity is U

[0102] The cross-sectional image analysis of the TPEE foam material was performed. In the obtained image, 12 areas of 150 mm × 80 mm were randomly selected, and the number of fillers in each area was calculated as pi, where i was 1, 2, 3…12, and the average number of fillers in the 12 areas was p, and the uniformity was U.

[0103]

[0104] (3) Mechanical properties testing

[0105] Tensile strength and elongation at break are tested according to ISO 527. Shore hardness is tested according to ISO 868. Resilience is tested according to ISO 4662.

[0106] Table 1 Performance results of TPEE foam materials of Examples 4 to 14

[0107]

[0108] From the results in Table 1, it can be seen that the present invention combines a hydrophilic core-shell composite foaming agent with a hydrophilic plastic filler, and the volume of the TPEE foam material obtained accounts for 18-35%, the distribution uniformity of the filler particles can reach more than 85%, and the foaming performance of the TPEE foam material is good. In addition, this TPEE foam material also has high tensile strength, elongation at break and Shore hardness, indicating that the mechanical strength of the TPEE foam material is high. The rebound resilience can reach more than 75%, indicating that it has better rebound performance.

[0109] The foaming agent in Example 11 has no organic acid modified layer on its surface and cannot be combined with the hydrophilic filler, which affects the distribution of the filler in the TPEE matrix. The uneven distribution not only affects the mechanical strength but also significantly reduces the resilience.

[0110] There is no epoxy resin modified layer on the surface of the foaming agent in Example 12, and the melting point of the sodium bicarbonate composite foaming agent is not increased much, resulting in premature foaming during the preparation of the TPEE foaming material and affecting its foaming performance, thereby also leading to a decrease in the distribution uniformity, tensile strength, fracture growth rate and resilience of the filler.

[0111] The foaming agent in Example 13 has neither an epoxy resin modified layer nor an organic acid modified layer, so the performance is quite different.

[0112] The filler shell layer in Example 14 is not hydrophilic and cannot be combined with the hydrophilic foaming agent, so the performance is also reduced.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A TPEE foam material, characterized in that: It includes a TPEE matrix, filler particles and holes between the TPEE matrix and the filler particles, the volume proportion of the holes is 18-35%, the distribution uniformity of the filler particles is U, U≥85%, and the preparation raw materials include 70-90 parts of thermoplastic polyester elastomer, 1-5 parts of foaming agent, 2-15 parts of filler and 0-10 parts of auxiliary agent in parts by weight, the foaming agent is a composite foaming agent with a core-shell structure, the shell layer of the composite foaming agent with a core-shell structure is hydrophilic, and the filler is a hydrophilic plastic filler.

2. The TPEE foam material according to claim 1, characterized in that: The melting point of the thermoplastic polyester elastomer is 140-170° C., the Shore hardness of the thermoplastic polyester elastomer is 30-60D, and the density of the thermoplastic polyester elastomer is 1.10-1.39 g / cm 3 .

3. The TPEE foam material according to claim 1, characterized in that: The thermoplastic polyester elastomer is obtained by polymerizing butylene terephthalate, polyether polyol and polyester polyol and introducing dimethyl isophthalate.

4. The TPEE foam material according to claim 1, characterized in that: The foaming agent is a sodium bicarbonate composite foaming agent, and the particle size of the foaming agent is 25 to 150 μm.

5. The TPEE foam material according to claim 4, characterized in that: The foaming agent comprises sodium bicarbonate particles, an epoxy resin layer and an organic acid modified layer from inside to outside.

6. The TPEE foam material according to claim 5, characterized in that: The material of the organic acid modified layer includes citric acid, palmitic acid or stearic acid.

7. The TPEE foam material according to claim 1, characterized in that: The filler is plastic particles grafted with maleic acid or acrylic acid, the melting point of the filler is 220-280° C., and the particle size of the filler is 0.5-3.0 mm.

8. The TPEE foam material according to claim 7, characterized in that: The plastic particles include at least one of epoxy resin particles, polycarbonate particles and polytetrafluoroethylene particles.

9. The TPEE foam material according to claim 1, characterized in that: The auxiliary agent includes at least one of a heat stabilizer, an anti-ultraviolet absorber and a lubricant.

10. The method for preparing a TPEE foam material according to any one of claims 1 to 9, characterized in that: Includes steps: (1) Spray granulation The foaming agent and the filler are mixed in a solvent and dispersed to obtain a suspension, and the suspension is spray-dried to obtain a foaming filler composition; (2) Premix Preliminarily melt-mixing the thermoplastic polyester elastomer and the auxiliary agent in a twin-screw extruder to obtain a primary mixture; (3) Injection molding The foaming filler composition is added into the primary mixture and mixed before injection molding.

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