TPU (thermoplastic polyurethane) foaming environment-friendly sole as well as formula and preparation method thereof

Abstract

The invention relates to the technical field of TPU (thermoplastic polyurethane) soles, in particular to a TPU foaming environment-friendly sole as well as a formula and a preparation method thereof. The preparation method of the TPU foaming environment-friendly shoe sole comprises the following steps: step 1, preparing and stirring raw materials of the shoe sole; step 2, pretreatment: pretreating the mixture to obtain a first mixture, pouring the mixture into a drying barrel, setting the temperature value to be 60-80 DEG C, drying the mixture for 0.3-0.7 hour, and pouring out the mixture after the drying time is up to obtain the first mixture; 3, retreatment, wherein the first mixture is poured into extrusion equipment to be retreated, and a second mixture is obtained; and 4, injection molding and shaping: injecting the second mixture into an injection mold for shoe sole shaping. According to the present invention, the formula composition required by shoemaking is simple, and the prepared sole has characteristics of strong toughness, good wear resistance, rapid molding, good stability and no secondary foaming during the preparation process.

Description

Technical Field

[0001] The present invention relates to the technical field of TPU soles, and in particular to a TPU foamed environmentally friendly sole, its formula and preparation method. Background Art

[0002] The structural composition of shoes mainly includes two parts: the upper and the sole. Common materials selected for the sole include rubber, EVA (ethylene vinyl acetate copolymer), PU (polyurethane), etc. Different materials are used to make the sole, and the effects produced are different. Under the same sole structure, choosing different materials will also change the wear resistance and anti-slip properties of the sole. Of course, with the continuous progress of technology, when preparing the sole, how to use a simple formula to make shoes, while meeting the usage requirements, reducing costs, reducing the weight of the sole, and improving environmental friendliness is also particularly important. Summary of the Invention

[0003] Other features and advantages of the present invention will be described in the following specification, and will be partially obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification and other specification drawings.

[0004] Soles made of rubber, EVA, and PU foam in the prior art all have problems such as heavy weight, secondary foaming, poor wear resistance, and due to the selection of the sole formula, the soles produced cannot be well recycled, and thus there are environmental friendliness problems.

[0005] The purpose of the present invention is to overcome the above deficiencies and provide a TPU foamed environmentally friendly sole, its formula and preparation method.

[0006] In a first aspect, the present invention provides a preparation method for a TPU foamed environmentally friendly sole, including:

[0007] Step 1: Prepare the sole raw materials and stir them. Mix 80 - 85 parts of thermoplastic polyurethane elastomer, 5 - 10 parts of chemical foaming agent + physical foaming agent, 3 - 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment, and stir evenly to obtain a mixture.

[0008] Step 2: Pretreat the mixture to obtain a first mixture. Pour the mixture into a drying barrel, set the temperature value to 60 - 80 degrees Celsius, dry for 0.3 - 0.7 hours, and after the drying time reaches, pour out to obtain the first mixture.

[0009] Step 3: Pour the first mixture into an extrusion device for reprocessing to obtain a second mixture. Set the parameters of each section of the screw in the extrusion device to be processed according to the set production temperature, pressure, pressure holding, and cooling time, and make appropriate adjustments to the parameters of each section. Among them, the screw of the extrusion device has three sections, namely the first section of the screw, with a temperature value of 170 - 180 °C, a pressure value of 110 - 120 MPa, a pressure holding time of 10 - 12 seconds, and a cooling time of 15 - 20 seconds; the second section of the screw, with a temperature value of 160 - 170 °C, a pressure value of 80 - 90 MPa, a pressure holding time of 10 - 12 seconds, and a cooling time of 15 - 20 seconds; the third section of the screw, with a temperature value of 150 - 160 °C, a pressure value of 50 - 60 MPa, a pressure holding time of 10 - 12 seconds, and a cooling time of 15 - 20 seconds;

[0010] Step 4: Inject the second mixture into an injection mold for sole shaping.

[0011] In some embodiments, the chemical blowing agent is azodicarbonamide. After being heated, the chemical blowing agent will decompose and release gases such as carbon dioxide and nitrogen, and these gases will form a compound with fine pores in the polymer.

[0012] In some embodiments, the physical blowing agent is cyclopentane. The fine pores of the physical blowing agent are formed by the physical state change of a certain substance, such as the expansion of compressed gas, the volatilization of liquid, or the dissolution of solid.

[0013] In a second aspect, the present invention provides a TPU foamed environmentally friendly sole, which is prepared by the preparation method of the first aspect.

[0014] In a third aspect, the present invention provides a formula for a TPU foamed environmentally friendly sole, including 80 - 85 parts of thermoplastic polyurethane elastomer, 5 - 10 parts of chemical blowing agent + physical blowing agent, 3 - 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment. Among them, the selection of sodium dodecyl sulfate can bring good emulsifying property, foaming property, water solubility, biodegradability, alkali resistance, and hard water resistance during preparation.

[0015] By adopting the above technical solutions, the beneficial effects of the present invention are:

[0016] The formula required for shoe making in the present invention is simple in composition. The prepared sole has strong toughness and good wear resistance, and has fast molding, good stability, and no secondary foaming during the preparation process. At the same time, the sole can be recycled and reused, can be naturally degraded, and has strong environmental protection.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure.

[0018] Without a doubt, such objectives of the present invention and other objectives will become more apparent after the detailed description of the preferred embodiments described in the following with multiple drawings and illustrations.

[0019] To make the above and other objectives, features, and advantages of the present invention more obvious and understandable, one or several preferred embodiments are specifically given below and, in conjunction with the accompanying drawings shown, are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention.

[0021] The drawings are schematic and not necessarily drawn to actual scale.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following-described drawings are only one or several embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on such drawings.

[0023] Figure 1 It is a schematic flow chart of the preparation method of the TPU foamed environmentally friendly sole for some embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In order to make the objectives, technical solutions, and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention but not to limit the present invention.

[0025] In addition, in the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0026] In the present invention, unless otherwise clearly specified or limited, terms such as "install", "connect", "link", "fix", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. However, indicating a direct connection means that there is no connection relationship constructed through a transition structure between the two connected main bodies, and they are only connected through the connection structure to form a whole. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0028] According to some embodiments of the present invention, the present invention provides a preparation method of an environmentally friendly TPU foamed sole, including:

[0029] Step 1: Prepare sole raw materials and stir them. Mix 80 - 85 parts of thermoplastic polyurethane elastomer, 5 - 10 parts of chemical blowing agent + physical blowing agent, 3 - 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment evenly to obtain a mixture.

[0030] Step 2: Pretreat the mixture to obtain a first mixture. Pour the mixture into a drying barrel, set the temperature value to 60 - 80 °C, dry for 0.3 - 0.7 hours, and after the drying time reaches, pour out to obtain the first mixture.

[0031] Step 3: Pour the first mixture into an extrusion device for reprocessing to obtain a second mixture. Set the parameters of each section of the screw in the extrusion device to be processed according to the set production temperature, pressure, pressure holding, and cooling time, and make appropriate adjustments to the parameters of each section. Among them, the screw of the extrusion device has three sections, namely the first section of the screw, with a temperature of 170 - 180 °C, a pressure of 110 - 120 MPa, a pressure holding time of 10 - 12 seconds, and a cooling time of 15 - 20 seconds; the second section of the screw, with a temperature of 160 - 170 °C, a pressure of 80 - 90 MPa, a pressure holding time of 10 - 12 seconds, and a cooling time of 15 - 20 seconds; the third section of the screw, with a temperature of 150 - 160 °C, a pressure of 50 - 60 MPa, a pressure holding time of 10 - 12 seconds, and a cooling time of 15 - 20 seconds;

[0032] Step 4: Inject the second mixture into an injection mold for sole shaping.

[0033] Through Step 2 of the present invention, the mixture is poured into a drying hopper for preliminary treatment according to set conditions. Through pretreatment, the mixture can be preliminarily mixed; the treatment temperature in Step 2 is the intermediate temperature value, avoiding the processing temperature of the mixture used for preparing the TPU foamed environmental protection sole from rising from room temperature (usually about 35 °C) to 170 °C all at once. Too rapid a temperature change will indirectly lead to poor preparation effects and unqualified yield rates; the temperature value of the mixture treated in Step 2 reaches 60 - 80 °C, and then it is subjected to the final stage of treatment by the three-section screw of the extrusion device, which is conducive to ensuring the preparation effect of the final TPU foamed environmental protection sole.

[0034] In the formula used in the method for preparing a TPU foamed environmental protection sole of the present invention, compared with the formula of the prior art, the types of formulas are fewer and simpler. After the prepared TPU foamed environmental protection sole samples are tested by a testing institution, they have advantages in wear resistance data and anti-slip data.

[0035] According to some embodiments of the present invention, optionally, the chemical blowing agent is azodicarbonamide. After being heated, the chemical blowing agent will decompose and release gases such as carbon dioxide and nitrogen, and these gases will form compounds with fine pores in the polymer.

[0036] According to some embodiments of the present invention, optionally, the physical blowing agent is cyclopentane. The fine pores of the physical blowing agent are formed by the physical state change of a certain substance, such as the expansion of compressed gas, the volatilization of liquid, or the dissolution of solid to form compounds.

[0037] According to some embodiments of the present invention, the present invention provides a TPU foamed environmental protection sole, which is prepared according to the steps in the above preparation method. When preparing the sole in the prior art, the formula is relatively complex. Compared with the simple formula components, the more types of formulas will, to a certain extent, affect the preparation stability.

[0038] According to some embodiments of the present invention, the present invention provides a formulation for a TPU foamed environmentally friendly sole, including 80-85 parts of thermoplastic polyurethane elastomer, 5-10 parts of chemical blowing agent + physical blowing agent, 3-5 parts of sodium dodecyl sulfate, 5-10 parts of masterbatch, and 3-5 parts of color powder pigment.

[0039] Example 1

[0040] This example provides a preparation method for a TPU foamed environmentally friendly sole, including:

[0041] Step 1: Prepare the sole raw materials and stir them. Mix 80-85 parts of thermoplastic polyurethane elastomer, 5-10 parts of chemical blowing agent + physical blowing agent, 3-5 parts of sodium dodecyl sulfate, 5-10 parts of masterbatch, and 3-5 parts of color powder pigment proportionally and stir evenly to obtain a mixed material; among them, the chemical blowing agent is azodicarbonamide, and the physical blowing agent is cyclopentane;

[0042] Step 2: Pretreat the mixed material to obtain a first mixed material. Pour the mixed material into a drying barrel, set the temperature value to 60-80 °C, dry for 0.3-0.7 hours, and after the drying time reaches, pour out to obtain the first mixed material;

[0043] Step 3: Pour the first mixed material into an extrusion device for further processing to obtain a second mixed material. Set the parameters of each section of the screw in the extrusion device to be processed according to the set production temperature, pressure, pressure holding, and cooling time, and appropriately adjust the parameters of each section. Among them, the screw of the extrusion device has three sections, namely the first section of the screw, with a temperature of 170-180 °C, a pressure of 110-120 MPa, a pressure holding of 10-12 seconds, and a cooling of 15-20 seconds; the second section of the screw, with a temperature of 160-170 °C, a pressure of 80-90 MPa, a pressure holding of 10-12 seconds, and a cooling of 15-20 seconds; the third section of the screw, with a temperature of 150-160 °C, a pressure of 50-60 MPa, a pressure holding of 10-12 seconds, and a cooling of 15-20 seconds;

[0044] Step 4: Inject the second mixed material into an injection mold for sole shaping.

[0045] Among them, in Step 3, each screw is optional. The first section of the screw, with a temperature of 170 °C, a pressure of 110 MPa, a pressure holding of 10 seconds, and a cooling of 15 seconds; the second section of the screw, with a temperature of 160 °C, a pressure of 80 MPa, a pressure holding of 10 seconds, and a cooling of 15 seconds; the third section of the screw, with a temperature of 150 °C, a pressure of 50 MPa, a pressure holding of 10 seconds, and a cooling of 15 seconds;

[0046] In Step 3, each screw is optional. For the first screw, the temperature is 180°C, the pressure is 120 MPa, the pressure holding time is 12 seconds, and the cooling time is 20 seconds; for the second screw, the temperature is 170°C, the pressure is 90 MPa, the pressure holding time is 12 seconds, and the cooling time is 20 seconds; for the third screw, the temperature is 160°C, the pressure is 60 MPa, the pressure holding time is 12 seconds, and the cooling time is 20 seconds.

[0047] In Step 3, each screw is optional. For the first screw, the temperature is 175°C, the pressure is 115 MPa, the pressure holding time is 11 seconds, and the cooling time is 18 seconds; for the second screw, the temperature is 165°C, the pressure is 85 MPa, the pressure holding time is 11 seconds, and the cooling time is 17 seconds; for the third screw, the temperature is 155°C, the pressure is 55 MPa, the pressure holding time is 11 seconds, and the cooling time is 18 seconds.

[0048] Example 2

[0049] This example provides an environmentally friendly TPU foam sole, which is prepared by the preparation method in Example 1. The formula in the environmentally friendly TPU foam sole includes thermoplastic polyurethane elastomer, chemical blowing agent + physical blowing agent, sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and color powder pigment. The formula and preparation method make the prepared environmentally friendly TPU foam sole have strong toughness, good wear resistance, fast molding, good stability, no secondary foaming, light weight, and recyclability.

[0050] Example 3

[0051] This example provides a formula for an environmentally friendly TPU foam sole, including 80 - 85 parts of thermoplastic polyurethane elastomer, 5 - 10 parts of chemical blowing agent + physical blowing agent, 3 - 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment. The masterbatch in the formula mainly increases the color stability and is not easy to change color and produce color difference.

[0052] Optionally, 80 parts of thermoplastic polyurethane elastomer, 5 parts of chemical blowing agent + physical blowing agent (2 parts of azodicarbonamide, 3 parts of cyclopentane), 3 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment. Among them, the usage amounts of the masterbatch and color powder pigment are determined according to the sole color, and the masterbatch increases the color stability of the color powder pigment;

[0053] Optionally, 85 parts of thermoplastic polyurethane elastomer, 10 parts of chemical blowing agent + physical blowing agent (5 parts of azodicarbonamide, 5 parts of cyclopentane), 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment;

[0054] Optionally, 83 parts of thermoplastic polyurethane elastomer, 7 parts of chemical blowing agent + physical blowing agent (4 parts of azodicarbonamide, 3 parts of cyclopentane), 4 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment.

[0055] Taking the TPU foamed environmentally friendly flat sole as an example, the TPU foamed environmentally friendly flat sole produced by the mold of the flat sole in the present invention is tested according to the following test items: GB / T3903.4-2017 "Footwear - Whole shoe test methods - Hardness", GB / T3903.6-2017 "Footwear - Whole shoe test methods - Slip resistance", GB / T 3903.2-2017 "Footwear - Whole shoe test methods - Abrasion resistance", GB / T 3903.1-2017 "Footwear - Whole shoe test methods - Flex resistance", GB / T 533-2008 "Vulcanized rubber or thermoplastic rubber - Determination of density". The test environment in the test items is carried out under the test environment conditions specified in the corresponding standards. The abrasion resistance test is about 5.8 mm, the hardness (Shore A) is 52 degrees, and the density is 0.56 g / cm 3 , the slip resistance (dynamic friction system; interface: ceramic tile; medium: tertiary water; mode: horizontal test) test value is 0.18, the slip resistance (dynamic friction system; interface: ceramic tile; medium: tertiary water; mode: forefoot test) test value is 0.17, the slip resistance (dynamic friction system; interface: ceramic tile; medium: tertiary water; mode: heel test) test value is 0.13, the slip resistance (dynamic friction system; interface: glass; medium: tertiary water; mode: horizontal test) test value is 0.13, the slip resistance (dynamic friction system; interface: glass; medium: tertiary water; mode: forefoot test) test value is 0.15, and the slip resistance (dynamic friction system; interface: glass; medium: tertiary water; mode: heel test) test value is 0.07. Among them, the abrasion resistance data of the present invention is 58, and the abrasion resistance data on the market is 230 - 250. The lower the abrasion resistance data value, the better the abrasion resistance effect; the anti-slip data of the present invention is 0.13 - 0.2, and the anti-slip data on the market is 0.05 - 0.08. The higher the anti-slip data value, the better the anti-slip effect.

[0056] It should be understood that the embodiments disclosed in the present invention are not limited to the specific processing steps or materials disclosed herein, but should extend to equivalent alternatives of such features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and do not imply limitation.

[0057] The "embodiments" mentioned in the specification mean that the specific features or characteristics described in connection with the embodiments are included in at least one embodiment of the present invention. Therefore, the phrases or "embodiments" that appear throughout the specification do not necessarily all refer to the same embodiment.

[0058] In addition, the described features or characteristics may be combined in any other suitable manner in one or more embodiments. In the above description, some specific details, such as thickness, quantity, etc., are provided to provide a comprehensive understanding of the embodiments of the present invention. However, those skilled in the relevant art will understand that the present invention may be implemented without one or more of the above specific details or may also be implemented using other methods, components, materials, etc.

Claims

1. A preparation method of an environmentally friendly TPU foamed sole, characterized in that, It includes the following steps: Step 1: Prepare the sole raw materials and stir them. Mix 80 - 85 parts of thermoplastic polyurethane elastomer, 5 - 10 parts of chemical blowing agent + physical blowing agent, 3 - 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment evenly to obtain a mixture; Step 2: Pretreatment. Pretreat the mixture to obtain a first mixture. Pour the mixture into a drying barrel, set the temperature value to 60 - 80 °C, dry for 0.3 - 0.7 hours. After the drying time is up, pour out to obtain the first mixture; Step 3: Re - treatment. Pour the first mixture into an extrusion device for re - treatment to obtain a second mixture; Step 4: Injection molding and shaping. Inject the second mixture into an injection mold for sole shaping.

2. The preparation method of the TPU foamed environmental protection sole according to claim 1, characterized in that, It also includes Step 5: Trim and remove the excess edges of the formed sole.

3. The preparation method of the TPU foamed environmental protection sole according to claim 1, characterized in that, The chemical blowing agent is azodicarbonamide.

4. The preparation method of the TPU foamed environmental protection sole according to claim 1, characterized in that, The physical blowing agent is cyclopentane.

5. The preparation method of the TPU foamed environmental protection sole according to claim 1, characterized in that, The production temperature, pressure value, holding pressure time, and cooling time of each section of the screw in the extrusion device are set according to the following parameters. The screw of the extrusion device has three sections, namely the first - stage screw, temperature value: 170 - 180 °C, pressure value: 110 - 120 MPa, holding pressure time: 10 - 12 s, cooling time: 15 - 20 s; the second - stage screw, temperature value: 160 - 170 °C, pressure value: 80 - 90 MPa, holding pressure time: 10 - 12 s, cooling time: 15 - 20 s; the third - stage screw, temperature value: 150 - 160 °C, pressure value: 50 - 60 MPa, holding pressure time: 10 - 12 s, cooling time: 15 - 20 s.

6. An environmentally friendly TPU foamed sole, characterized in that, The TPU - foamed environmental - protection sole is prepared by the preparation method of the TPU - foamed environmental - protection sole according to any one of claims 1 - 5.

7. A formula for an environmentally friendly TPU foamed sole, characterized in that, The formula consists of the following materials in parts by mass: 80 - 85 parts of thermoplastic polyurethane elastomer, 5 - 10 parts of chemical blowing agent + physical blowing agent, 3 - 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment.

8. The formulation of the environmentally friendly TPU foam sole according to claim 7, characterized in that, The formula consists of the following materials in parts by mass: 80 parts of thermoplastic polyurethane elastomer, 2 parts of azodicarbonamide, 3 parts of cyclopentane, 3 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment.

9. The formulation of the environmentally friendly TPU foamed sole according to claim 7, characterized in that, The formula consists of the following materials in parts by mass: 85 parts of thermoplastic polyurethane elastomer, 5 parts of azodicarbonamide, 5 parts of cyclopentane, 5 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment.

10. The formulation of the TPU foamed environmentally friendly sole according to claim 7, characterized in that, The formula consists of the following materials in parts by mass: 83 parts of thermoplastic polyurethane elastomer, 4 parts of azodicarbonamide, 3 parts of cyclopentane, 4 parts of sodium dodecyl sulfate, 5 - 10 parts of masterbatch, and 3 - 5 parts of color powder pigment.

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