Low-shrinkage nylon elastomer foaming material as well as preparation method and application thereof

Abstract

The invention provides a low-shrinkage nylon elastomer foaming material as well as a preparation method and application thereof. The shrinkage rate of the low-shrinkage nylon elastomer foaming material is 0.2%-0.8%, the vertical rebound resilience is 75%-90%, and the density is 0.05-0.10 g / cm < 3 >. The nylon elastomer foaming material provided by the invention has the advantages of lower shrinkage rate, better vertical resilience and high foaming ratio, and can be used in the fields of insoles, shoe insoles, saddles, tires, helmets, cushions, indoor ornaments, sports equipment and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of elastomer materials and relates to a low-shrinkage nylon elastomer foam material and a preparation method and application thereof. Background Art

[0002] At present, the foaming processes of nylon elastomer foam materials mainly include bead foaming, sheet foaming, embryo mold foaming, micro-foam injection molding, etc.

[0003] Supercritical fluid foaming technology uses inert gases such as supercritical CO2 / N2 as foaming gases for foaming. Compared with traditional physical foaming agents such as alkanes and freons, supercritical fluids have the advantages of wide sources, environmental friendliness, and non-flammability. However, particles foamed with supercritical CO2 have serious shrinkage problems. This severe shrinkage not only significantly increases the density of the foamed material, but also causes obvious wrinkles and depressions on the surface of the foamed material, seriously affecting the subsequent use of the foamed material. At present, the shrinkage problem is generally improved by blending other polymers, dimensional stabilizers or nucleating agents, but these methods will increase costs on the one hand and reduce the foaming ratio on the other.

[0004] CN116323138A discloses a method and apparatus for manufacturing foamed articles, wherein a thermoplastic elastomer material and carbon dioxide are used for foaming. By injecting carbon dioxide into a solid foamable material and expanding the carbon dioxide without softening the solid material, a foamed material having a low-density, uniform porous foam structure and beneficial properties can be formed. However, in the method of the invention, the state of the material changes during the heating and pressurizing process, and uniform pores cannot be obtained.

[0005] Therefore, in the art, it is desired to develop a nylon elastomer foam material, which has a lower shrinkage rate, a high foaming ratio, a uniform pore distribution, and a lower cost. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a low-shrinkage nylon elastomer foam material and a preparation method and application thereof. The preparation method of the low-shrinkage nylon elastomer foam material provided by the present invention overcomes the problem of complex process of the foaming method of nylon elastomer in the prior art and solves the defect of large shrinkage rate of the foamed material. The present invention adopts a supercritical fluid foaming method with simple process and low energy consumption, which effectively improves production efficiency; at the same time, the nylon elastomer foam material prepared by the present invention has a high foaming ratio, a small shrinkage rate, a small pore diameter, and excellent mechanical properties.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a low shrinkage nylon elastomer foam material, wherein the shrinkage rate of the low shrinkage nylon elastomer foam material is 0.2% to 0.8% (for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, etc.), the vertical resilience is 75% to 90% (for example, 75%, 76%, 77%, 78%, 79%, 80%, 82%, 84%, 86%, 88%, 90%, etc.), and the density is 0.05 to 0.10 g / cm 3 (e.g. 0.05 g / cm 3 , 0.06g / cm 3 , 0.07g / cm 3 , 0.08g / cm 3 , 0.09g / cm 3 , 0.10g / cm 3 wait).

[0009] The nylon elastomer foam material provided by the invention has lower shrinkage, better vertical resilience and high foaming ratio. The nylon elastomer foam material can be used in the fields of insoles, midsoles, saddles, tires, helmets, cushions, interior decorations and sports equipment.

[0010] In a second aspect, the present invention provides a method for preparing the low shrinkage nylon elastomer foam material as described in the first aspect, the preparation method comprising:

[0011] Adding a nylon elastomer into a container, then injecting a supercritical fluid, and heating the container in stages to a foaming temperature for foaming to obtain the low shrinkage nylon elastomer foam material;

[0012] The average torque of the nylon elastomer at 150° C. and in the range of 100 to 200 s is 5 to 60 N·m, for example 5 N·m, 8 N·m, 10 N·m, 12 N·m, 14 N·m, 16 N·m, 18 N·m, 20 N·m, 22 N·m, 24 N·m, 26 N·m, 28 N·m, 30 N·m, 32 N·m, 34 N·m, 36 N·m, 38 N·m, 40 N·m, 42 N·m, 44 N·m, 46 N·m, 48 N·m, 50 N·m, 52 N·m, 54 N·m, 56 N·m, 58 N·m, 60 N·m, etc. The test method for the torque average value is as follows: use a torque rheometer for testing, the test temperature is 150°C, the test time is 8 to 12 minutes, the sample addition amount is 30 to 50g, and the average value within the range of 100s to 200s is taken.

[0013] The preparation method of the low shrinkage nylon elastomer foam material provided by the invention adopts supercritical fluid foaming technology, limits the torque average value of the nylon elastomer within a specific range at 150° C. and within a range of 100 to 200 seconds, and adopts a staged heating method to raise the temperature to the foaming temperature for foaming, so that the prepared nylon elastomer foam material has low relative density, uniform pore distribution, low shrinkage rate (0.2% to 0.8%) and high vertical resilience (75% to 90%). The nylon elastomer foam material can be used in the fields of insoles, midsoles, saddles, tires, helmets, cushions, interior decorations, sports equipment, etc.

[0014] Preferably, the average torque value of the nylon elastomer at 150° C. and within the range of 100 to 200 s is 5 to 40 N·m.

[0015] Preferably, the container comprises any one of a high-pressure reactor and a foaming reactor.

[0016] Preferably, the supercritical fluid comprises any one of carbon dioxide, nitrogen, helium, and argon, or a combination of at least two thereof, preferably carbon dioxide and / or nitrogen.

[0017] Preferably, after the supercritical fluid is injected, the supercritical state is maintained.

[0018] Preferably, the pressure for maintaining the supercritical state is 10 to 100 MPa, for example, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, 75 MPa, 80 MPa, 85 MPa, 90 MPa, 95 MPa, 100 MPa, etc., preferably 10 to 50 MPa.

[0019] Preferably, the heating rate of the staged heating is 5 to 20°C / min, for example, 5°C / min, 6°C / min, 8°C / min, 10°C / min, 12°C / min, 14°C / min, 16°C / min, 18°C / min, 20°C / min, etc., preferably 10 to 15°C / min.

[0020] Preferably, when the temperature is raised in stages, the temperature is kept constant for 10 to 30 minutes (for example, 10 minutes, 13 minutes, 15 minutes, 16 minutes, 18 minutes, 20 minutes, 23 minutes, 25 minutes, 28 minutes, 30 minutes, etc.) every time the temperature is raised by 30 to 50 degrees Celsius (for example, 30 degrees Celsius, 35 degrees Celsius, 40 degrees Celsius, 45 degrees Celsius, 50 degrees Celsius, etc.), preferably for 15 to 20 minutes.

[0021] Preferably, the foaming temperature is (T m -40℃)~(Tm +10℃), for example, T m -40℃、T m -35℃、T m -30℃、T m -25℃、T m -20℃、T m -15℃、T m -10℃、T m -5℃、T m ℃、T m +5℃、T m +10℃, etc., preferably (T m -30℃)~(Tm), where T m is the melting temperature of nylon elastomer.

[0022] Preferably, the foaming pressure is 10-50 MPa, for example, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, etc.

[0023] Preferably, the raw materials for preparing the nylon elastomer include polyamide and polyglycol, wherein the polyamide serves as the hard segment of the nylon elastomer and the polyglycol serves as the soft segment of the nylon elastomer.

[0024] Preferably, the polyamide is selected from PA6, PA11, PA12, PA5.4, PA5.9, PA5.10, PA5.12, PA5.13, PA5.14, PA5.16, PA5.18, PA5.36, PA6.4, PA6.9, PA6.10, PA6.12, PA6.13, PA6.14, PA6.16, PA6.18, PA6.36, PA10.4, PA1 0.9, PA10.10, PA10.12, PA10.13, PA10.14, PA10.16, PA10.18, PA10.36, PA10.T, PA12.4, PA12.9, PA12.10, PA12.12, PA12.13, PA12.14, PA12.16, PA12.18, PA12.36 or PA12.T, or a combination of at least two of them.

[0025] Preferably, the polyglycol is selected from any one or a combination of at least two of polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, polycaprolactone, polyester glycol synthesized from diol and dibasic acid, and polycarbonate glycol.

[0026] Preferably, the molar ratio of the polyamide to the polyglycol is (0.98-1.02):1, for example, 0.98:1, 0.99:1, 1:1, 1.01:1, 1.02:1, etc.

[0027] Preferably, the raw materials for preparing the nylon elastomer further include a catalyst and / or an antioxidant.

[0028] Preferably, the catalyst comprises zirconium n-butoxide and / or tetrabutyl titanate.

[0029] Preferably, the antioxidant includes antioxidant 168 and / or antioxidant 1098.

[0030] Preferably, based on the total weight of the polyamide and the polyglycol as 100%, the amount of the catalyst is 0.1% to 0.3%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc.

[0031] Preferably, based on the total weight of polyamide and polyglycol as 100%, the amount of the antioxidant is 0-0.5%, for example, 0 (not added), 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0032] Preferably, the hardness of the nylon elastomer is 20-55D, for example, 20D, 25D, 30D, 35D, 40D, 45D, 50D, 55D, etc., preferably 25-45D.

[0033] Preferably, the nylon elastomer is foamed in any form, and may be bead foaming, post-foaming of a plate, injection molding foaming, compression molding foaming, or extrusion foaming, and may form a foamed material having a low-density, uniform porous foam structure and beneficial properties.

[0034] Preferably, the nylon elastomer is prepared by the following method:

[0035] The polyamide and the polyglycol are melted, and then an optional catalyst and an optional antioxidant are added, reacted, and extruded into pellets to obtain the nylon elastomer.

[0036] Preferably, the melting is carried out under an inert gas atmosphere.

[0037] Preferably, the inert gas comprises nitrogen.

[0038] Preferably, the reaction temperature is 200-240°C, for example, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, etc., and the reaction time is 2-4h, for example, 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0039] Preferably, the temperature of the extrusion granulation is 160-230°C, for example, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, etc.

[0040] As a preferred technical solution of the present invention, the preparation method comprises:

[0041] (1) melting polyamide and polyglycol under an inert gas atmosphere, then adding an optional catalyst and an optional antioxidant, reacting at 200 to 240° C. for 2 to 4 hours, and extruding and granulating at 160 to 230° C. to obtain a nylon elastomer; the nylon elastomer has an average torque of 5 to 60 N·m at 150° C. and within a range of 100 to 200 seconds;

[0042] (2) The nylon elastomer obtained in step (1) is added into a container, and then a supercritical fluid is injected. The temperature is raised to the foaming temperature at a rate of 5 to 20°C / min in a stepwise manner, and the temperature is kept constant for 10 to 30 minutes every time the temperature is raised by 30 to 50°C. The foaming is carried out at 10 to 50 MPa to obtain the low shrinkage nylon elastomer foam material.

[0043] In a third aspect, the present invention provides a use of the low shrinkage nylon elastomer foam material as described in the first aspect in insoles, shoe midsoles, saddles, tires, helmets, cushions, interior decorations, and sports equipment.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The nylon elastomer foam material provided by the invention has lower shrinkage, better vertical resilience and high foaming ratio. The nylon elastomer foam material can be used in the fields of insoles, midsoles, saddles, tires, helmets, cushions, interior decorations and sports equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a torque test curve of the nylon elastomer obtained in step (1) of Example 1 of the present invention.

[0047] Figure 2 This is a SEM image of the nylon elastomer foam material provided in Example 1 of the present invention.

[0048] Figure 3 This is a SEM image of the nylon elastomer foam material provided for Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0049] The technical scheme of the present invention is further described below by specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. The experimental methods without specific conditions in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0050] Example 1

[0051] In this embodiment, a low shrinkage nylon elastomer foam material is provided, and a preparation method thereof comprises the following steps:

[0052] (1) 1 mol of polyamide (polyamide 612, number average molecular weight of 500) and 1 mol of polyglycol (polybutylene glycol, number average molecular weight of 1500) were melted under a nitrogen atmosphere, and then 0.1% of zirconium n-butoxide and 0.2% of antioxidant 168 based on the total weight of polyamide and polyglycol were added, reacted at 200°C for 4 hours, and extruded through a 160°C outlet to obtain nylon elastomer;

[0053] (2) Preparation of foamed beads: 1 kg of the above nylon elastomer, 15 MPa of carbon dioxide and 1 kg of water were added to a 20 L high pressure reactor to form a suspension, and then the temperature was raised to 140°C at a heating rate of 10°C / min, and the temperature was kept constant for 20 min every time the temperature was raised by 40°C. The pressure was maintained at 15 MPa to foam, and the suspension in the pressure vessel was discharged into the atmosphere and dried to obtain foamed beads.

[0054] The foamed beads obtained above were filled into a mold of 300 mm long × 200 mm wide × 40 mm thick, and water vapor at a pressure of 1.2 bar was used to compress the mold by 15% along the thickness direction to bond the particles into shape, finally obtaining a molded foam product, which was then placed at room temperature for 48 hours.

[0055] Example 2

[0056] In this embodiment, a low shrinkage nylon elastomer foam material is provided, and a preparation method thereof comprises the following steps:

[0057] (1) 0.995 mol of polyamide (polyamide 12, number average molecular weight of 500) and 1 mol of polyglycol (polybutylene glycol, number average molecular weight of 2000) were melted under a nitrogen atmosphere, and then 0.25% of zirconium n-butoxide and 0.5% of antioxidant 168 accounting for the total weight of polyamide and polyglycol were added, reacted at 240°C for 3 hours, and extruded and granulated through a discharge port at 230°C to obtain a nylon elastomer;

[0058] (2) Preparation of foamed sheet: The above nylon elastomer is extruded through a screw to obtain a 15 mm thick sheet, the sheet is placed in a foaming kettle, filled with 10 MPa carbon dioxide and 15 MPa nitrogen, and then heated to 145°C at a heating rate of 15°C / min, and the temperature is kept constant for 10 minutes every time the temperature is increased by 30°C. The pressure is maintained at 25 MPa to foam, and the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmosphere to obtain a foamed sheet.

[0059] Example 3

[0060] In this embodiment, a low shrinkage nylon elastomer foam material is provided, and a preparation method thereof comprises the following steps:

[0061] (1) 1.01 mol of polyamide (polyamide 12, number average molecular weight of 1000) and 1 mol of polyglycol (polybutylene glycol, number average molecular weight of 2000) were melted under a nitrogen atmosphere, and then 0.15% of zirconium n-butoxide accounting for the total weight of polyamide and polyglycol was added, reacted at 220° C. for 3 h, and extruded through a 220° C. outlet to obtain nylon elastomer;

[0062] (2) Preparation of foamed sheet: The above nylon elastomer is extruded through a screw to obtain a 15 mm thick sheet, the sheet is placed in a foaming kettle, filled with 7 MPa carbon dioxide and 13 MPa nitrogen, and then heated to 145°C at a heating rate of 10°C / min. The temperature is kept constant for 10 minutes every time the temperature is increased by 20°C. The pressure is maintained at 20 MPa to foam, and the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmosphere to obtain a foamed sheet.

[0063] Example 4

[0064] In this embodiment, a low shrinkage nylon elastomer foam material is provided, and a preparation method thereof comprises the following steps:

[0065] (1) 1.01 mol of polyamide (polyamide 612, number average molecular weight of 1000) and 1 mol of polyglycol (polypropylene glycol, number average molecular weight of 1000) were melted under a nitrogen atmosphere, and then 0.15% of tetrabutyl titanate and 0.3% of antioxidant 1098 accounting for the total weight of polyamide and polyglycol were added in sequence, reacted at 220°C for 3 hours, and extruded through a 200°C outlet to obtain nylon elastomer;

[0066] (2) The nylon elastomer is injection molded into a small shoe midsole embryo, which is then placed in a foaming kettle and filled with 5 MPa of carbon dioxide and 25 MPa of nitrogen. The temperature is then raised to 125°C at a heating rate of 5°C / min, and the temperature is kept constant for 30 minutes every time the temperature is raised by 50°C. The pressure is maintained at 30 MPa for foaming, and the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmosphere to obtain a large foamed shoe embryo.

[0067] Example 5

[0068] In this embodiment, a low shrinkage nylon elastomer foam material is provided, and a preparation method thereof comprises the following steps:

[0069] (1) 1 mol of polyamide (polyamide 612, number average molecular weight of 1000) and 1 mol of polyglycol (PTMEG, number average molecular weight of 1000) were melted under a nitrogen atmosphere, and then 0.3% of tetrabutyl titanate accounting for the total weight of polyamide and polyglycol was added, reacted at 230°C for 2h, and extruded through a 200°C outlet to obtain nylon elastomer;

[0070] (2) The above-mentioned nylon elastomer is added to the screw system of the injection molding machine, and 5 MPa of carbon dioxide and 15 MPa of nitrogen are filled. Then, the temperature is raised to 160°C at a heating rate of 20°C / min, and the temperature is kept constant for 30 minutes every time the temperature is raised by 30°C. The pressure is maintained at 20 MPa, and then the melt is injected into the mold cavity through a switch nozzle to obtain an injection molded foam sheet.

[0071] Example 6

[0072] In this embodiment, a low shrinkage nylon elastomer foam material is provided, and a preparation method thereof comprises the following steps:

[0073] (1) 1 mol of polyamide (polyamide 612, number average molecular weight of 1000) and 1 mol of polyglycol (polypropylene glycol, number average molecular weight of 1000) were melted under a nitrogen atmosphere, and then 0.2% of tetrabutyl titanate and 0.2% of antioxidant 1098 accounting for the total weight of polyamide and polyglycol were added, reacted at 200°C for 4 hours, and extruded and granulated through a 180°C outlet to obtain a nylon elastomer;

[0074] (2) Preparation of foamed sheet: The above nylon elastomer is extruded through a screw to obtain a 10 mm thick sheet, the sheet is placed in a foaming kettle, filled with 5 MPa carbon dioxide and 15 MPa nitrogen, and then heated to 145°C at a heating rate of 10°C / min. The temperature is kept constant for 20 minutes every time the temperature is increased by 50°C. The pressure is maintained at 20 MPa to foam, and the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmosphere to obtain a foamed sheet.

[0075] Example 7

[0076] The only difference between this embodiment and embodiment 1 is that in step (2), the temperature is kept constant for 20 minutes every time the temperature is increased by 55°C.

[0077] Example 8

[0078] The only difference between this embodiment and embodiment 1 is that in step (2), the temperature is increased to 140° C. at a heating rate of 25° C. / min.

[0079] Comparative Example 1

[0080] In this comparative example, a low shrinkage nylon elastomer foam material is provided, and the preparation method thereof comprises the following steps:

[0081] (1) 1 mol of polyamide (polyamide 612, number average molecular weight of 500) and 1 mol of polyglycol (polypropylene glycol, number average molecular weight of 3000) were melted under a nitrogen atmosphere, and then 0.2% of tetrabutyl titanate and 0.2% of antioxidant 1098 accounting for the total weight of polyamide and polyglycol were added, reacted at 200°C for 4 hours, and extruded and granulated through a 180°C outlet to obtain a nylon elastomer;

[0082] (2) Preparation of foamed sheet: The above nylon elastomer is extruded through a screw to obtain a 10 mm thick sheet, the sheet is placed in a foaming kettle, filled with 5 MPa carbon dioxide and 15 MPa nitrogen, and then heated to 145°C at a heating rate of 10°C / min. The temperature is kept constant for 20 minutes every time the temperature is increased by 50°C. The pressure is maintained at 20 MPa to foam, and the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmosphere to obtain a foamed sheet.

[0083] Comparative Example 2

[0084] The only difference between this comparative example and Example 1 is that step (2) does not include the step of "maintaining the temperature for 20 minutes every time the temperature rises by 40° C.", that is, the temperature is not raised to the foaming temperature in a stepwise manner.

[0085] The nylon elastomer obtained in step (1) of the embodiment and the comparative example was tested, and the test method was as follows:

[0086] (1) Torque: The test was conducted using a torque rheometer model RM200C produced by Harbin Harpu Electric Technology Co., Ltd. The test temperature was 150°C, the test time was 10 min, the sample addition amount was 40 g, and the average value within the range of 100 s to 200 s was taken;

[0087] (2) Hardness: Tested in accordance with ASTM D2240-15(2021).

[0088] The test results are shown in Table 1.

[0089] The torque test curve of the nylon elastomer obtained in step (1) of Example 1 of the present invention is as follows: Figure 1 shown.

[0090] The nylon elastomer foam material provided in the embodiment and the comparative example was passed through a layer splitting machine to remove the surface crust, and then cut into samples according to the test standard, and the performance test was performed on the samples. The test method is as follows:

[0091] (1) Shrinkage: Tested in accordance with ISO 294-4 2577;

[0092] (2) Ball rebound: Tested in accordance with ASTM 2632;

[0093] (3) Density: Tested in accordance with ASTM D792.

[0094] The performance test results are shown in Table 1.

[0095] Table 1

[0096]

[0097] It can be seen from Table 1 that the nylon elastomer foam materials provided in the embodiments of the present invention have a relatively low shrinkage rate (0.3% to 0.8%) and a relatively good ball rebound resilience (81% to 84%), and a high foaming ratio (density: 0.05-0.10 g / cm 3 ).

[0098] Compared with Example 6, the shrinkage rate of the nylon elastomer foam material provided in Comparative Example 1 is significantly increased, and the ball rebound resilience is significantly deteriorated.

[0099] Compared with Example 1, the shrinkage rate of the nylon elastomer foam material provided in Comparative Example 2 is significantly increased, and the ball rebound resilience is significantly deteriorated.

[0100] The SEM images of the nylon elastomer foam materials provided in Example 1 and Comparative Example 2 of the present invention are shown in FIG. Figure 2 and Figure 3 As shown, it can be seen that compared with Comparative Example 2, the cells of the nylon elastomer foam material provided in Example 1 are more uniform.

[0101] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the low-shrinkage nylon elastomer foam material and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A low shrinkage nylon elastomer foam material, characterized in that: The low shrinkage nylon elastomer foam material has a shrinkage rate of 0.2% to 0.8%, a vertical resilience of 75% to 90%, and a density of 0.05 to 0.10 g / cm 3 .

2. A method for preparing a low shrinkage nylon elastomer foam material as claimed in claim 1, characterized in that: The preparation method comprises: Adding a nylon elastomer into a container, then injecting a supercritical fluid, and heating the container in stages to a foaming temperature for foaming to obtain the low shrinkage nylon elastomer foam material; The torque average value of the nylon elastomer at 150° C. and within the range of 100 to 200 seconds is 5 to 60 N·m.

3. The preparation method according to claim 2, characterized in that: The supercritical fluid includes any one of carbon dioxide, nitrogen, helium, and argon, or a combination of at least two of them.

4. The preparation method according to claim 2, characterized in that: The heating rate of the staged heating is 5 to 20°C / min; When the temperature is raised in stages, the temperature is kept constant for 10 to 30 minutes each time the temperature is raised by 30 to 50°C.

5. The preparation method according to claim 2, characterized in that: The foaming temperature is (T m -40℃)~(T m +10℃), where T m is the melting temperature of nylon elastomer; The foaming pressure is 10-50 MPa.

6. The preparation method according to claim 2, characterized in that: The raw materials for preparing the nylon elastomer include polyamide and polyglycol; The polyamide is selected from PA6, PA11, PA12, PA5.4, PA5.9, PA5.10, PA5.12, PA5.13, PA5.14, PA5.16, PA5.18, PA5.36, PA6.4, PA6.9, PA6.10, PA6.12, PA6.13, PA6.14, PA6.16, PA6.18, PA6.36, PA10.4, PA10.

9. Any one of PA10.10, PA10.12, PA10.13, PA10.14, PA10.16, PA10.18, PA10.36, PA10.T, PA12.4, PA12.9, PA12.10, PA12.12, PA12.13, PA12.14, PA12.16, PA12.18, PA12.36 or PA12.T, or a combination of at least two thereof; The polyglycol is selected from any one or a combination of at least two of polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, polycaprolactone, polyester glycol synthesized from diols and dibasic acids, and polycarbonate diol; The molar ratio of the polyamide to the polyglycol is (0.98-1.02):

1.

7. The preparation method according to claim 6, characterized in that: The raw materials for preparing the nylon elastomer also include a catalyst and / or an antioxidant; Based on the total weight of the polyamide and the polyglycol being 100%, the amount of the catalyst is 0.1% to 0.3%, and the amount of the antioxidant is 0 to 0.5%.

8. The preparation method according to claim 6, characterized in that: The nylon elastomer is prepared by the following method: The polyamide and the polyglycol are melted in an inert gas atmosphere, and then an optional catalyst and an optional antioxidant are added, reacted at 200-240° C. for 2-4 hours, and extruded and granulated at 160-230° C. to obtain the nylon elastomer.

9. The preparation method according to claim 2, characterized in that: The preparation method comprises: (1) melting polyamide and polyglycol under an inert gas atmosphere, then adding an optional catalyst and an optional antioxidant, reacting at 200 to 240° C. for 2 to 4 hours, and extruding and granulating at 160 to 230° C. to obtain a nylon elastomer; the nylon elastomer has an average torque of 5 to 60 N·m at 150° C. and within a range of 100 to 200 seconds; (2) The nylon elastomer obtained in step (1) is added into a container, and then a supercritical fluid is injected. The temperature is raised to the foaming temperature at a rate of 5 to 20°C / min in a stepwise manner, and the temperature is kept constant for 10 to 30 minutes every time the temperature is raised by 30 to 50°C. The foaming is carried out at 10 to 50 MPa to obtain the low shrinkage nylon elastomer foam material.

10. Use of the low shrinkage nylon elastomer foam material as claimed in claim 1 in insoles, midsoles, saddles, tires, helmets, cushions, interior decorations, and sports equipment.

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