A polyamide elastomer foam material with a bimodal cell structure and a preparation method thereof

Abstract

The present invention relates to the technical field of polymer foaming materials, and provides a polyamide elastomer foam material with a bimodal pore structure and a preparation method thereof. The present invention utilizes foaming gas CO2 to perform saturation treatment on a polyamide elastomer sheet solid sample, wherein the first saturation treatment is to perform a melting treatment on the polyamide elastomer to eliminate crystals; by regulating the temperature and time of the second saturation treatment, the weight crystallization degree of the polyamide elastomer is regulated to be 1.1-10%, thereby preparing a polyamide elastomer foam material with a bimodal structure having controllable pore size; since the temperature and pressure of the second saturation treatment are under the supercritical condition of CO2, the foaming temperature range is widened, and not only the polyamide elastomer foam material with a bimodal pore structure is obtained, but also the foaming ratio of the polyamide elastomer foam material is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer foaming materials, and in particular relates to a polyamide elastomer foam material with a bimodal pore structure and a preparation method thereof. Background Art

[0002] Polymer foam materials are composite materials with a polymer material as the matrix and filled with a large number of interconnected or unconnected micropores. Among them, polyamide elastomer is a type of thermoplastic elastomer material with alternating soft and hard segments, the hard segment of which is a crystalline polyamide (nylon 6, nylon 12, etc.), and the soft segment is a polyether, polyester or polycarbonate. By regulating the crystallization behavior of polyamide elastomer, a cellular material with a bimodal cellular structure can be prepared after intermittent physical foaming. Compared with foam materials with uniform cellular structures, polymer foam materials with a bimodal cellular structure have higher barrier properties, in which small pores can provide good mechanical properties, etc., while large pores can reduce the apparent density of the material. Therefore, polymer foam materials with a bimodal cellular structure have attracted widespread attention.

[0003] As a semi-crystalline polymer, the existence of the crystal region in the thermoplastic polyamide elastomer makes it difficult to foam at a lower temperature due to its rigidity during the foaming process, while at a higher temperature, the melt strength is insufficient to support the growth of the pores and it is also difficult to foam, which is manifested as a narrow foaming temperature range. At present, the main methods for preparing foam materials with a bimodal pore structure are a two-step pressure relief foaming method, a double foaming agent method, and a multi-phase system co-foaming method. The two-step pressure relief foaming method is usually used to prepare foam materials with both large and small bubbles. Not only does it have many production steps, but the foaming ratio of the obtained foam material is also low. The double foaming agent method mainly uses the solubility of two different foaming agents in the polymer and the difference in the nucleation and growth of the pores to form a foam material with a bimodal pore structure, but the selection of the foaming agent in this method is relatively difficult. Although the multi-phase system co-foaming method has a high foaming rate, it has many production steps and requires a variety of additives.

[0004] Therefore, there is an urgent need to provide a method for preparing a polyamide elastomer foam material with a bimodal pore structure that is simple in preparation, does not require the addition of other additives, and has a high foaming ratio and a wide foaming temperature range. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a polyamide elastomer foam material with a bimodal pore structure. The preparation method provided by the present invention is simple, does not require the addition of other additives, and has the advantages of high foaming ratio and wide foaming temperature range.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a polyamide elastomer foam material having a bimodal pore structure, comprising the following steps:

[0008] (1) subjecting polyamide elastomer particles to a melt heat-pressing treatment to obtain a polyamide elastomer flake solid sample;

[0009] (2) using a foaming gas CO2 to perform a saturation treatment on the polyamide elastomer sheet solid sample obtained in step (1) to obtain a saturated treatment system;

[0010] The saturation treatment includes two stages: a first saturation treatment and a second saturation treatment; wherein the pressures of the first saturation treatment and the second saturation treatment are independently 10 to 20 MPa;

[0011] The temperature of the first saturation treatment is higher than T m 10-30°C, fully melt the polyamide elastomer sheet solid sample;

[0012] The temperature of the second saturation treatment is lower than T m 20°C to 50°C, the second saturation treatment time is in the range of 5 to 60 minutes, and by adjusting the temperature and time of the second saturation treatment, the weight crystallinity of the polyamide elastomer during the second saturation treatment is adjusted to 1.1 to 10%;

[0013] The T m is the melting temperature of the polyamide elastomer;

[0014] (3) The saturated treatment system obtained in step (2) is subjected to pressure release foaming and cooling and shaping in sequence to obtain a polyamide elastomer foam material with a bimodal pore structure.

[0015] Preferably, the hard segment of the polyamide elastomer in step (1) includes at least one of polyamide 6, polyamide 12, polyamide 10, polyamide 11 and polyamide 1212, and the soft segment of the polyamide elastomer includes at least one of polyether, polyester, polyether ester and polycarbonate.

[0016] Preferably, the temperature of the melt hot pressing treatment in step (1) is higher than T m The temperature is 20°C to 60°C, the pressure of the melt hot pressing treatment is 4 to 15 MPa, and the time of the melt hot pressing treatment is 5 to 10 minutes.

[0017] Preferably, the thickness of the polyamide elastomer solid sample in step (1) is 1 to 5 mm.

[0018] Preferably, the cooling rate from the temperature of the first saturation treatment in step (2) to the temperature of the second saturation treatment is 5 to 20° C. / min.

[0019] Preferably, the time of the first saturation treatment in step (2) is 5 to 60 minutes.

[0020] Preferably, the pressure release rate of the pressure release foaming in step (3) is 5 to 30 MPa / s.

[0021] Preferably, the cooling and shaping method in step (3) is water cooling.

[0022] The present invention also provides a polyamide elastomer foam material with a bimodal pore structure prepared by the preparation method described in the above scheme, wherein the polyamide elastomer foam material with a bimodal pore structure comprises a plurality of large pores and a plurality of small pores, wherein the average pore diameter of the large pores is 30 to 200 μm, and the average pore diameter of the small pores is 0.6 to 15 μm; wherein the pore diameter of the large pores is one order of magnitude larger than the pore diameter of the small pores.

[0023] The present invention provides a method for preparing a polyamide elastomer foam material with a bimodal cell structure, comprising the following steps: (1) subjecting polyamide elastomer particles to a melt hot-pressing treatment to obtain a polyamide elastomer sheet solid sample; (2) subjecting the polyamide elastomer sheet solid sample to a saturation treatment using a foaming gas CO2 to obtain a saturated treatment system; the saturation treatment comprises two stages: a first saturation treatment and a second saturation treatment; wherein the pressures of the first saturation treatment and the second saturation treatment are independently 10 to 20 MPa; and the temperature of the first saturation treatment is higher than T m 10~30 ℃, fully melt the polyamide elastomer sheet solid sample; the temperature of the second saturation treatment is lower than T m 20°C to 50°C, the second saturation treatment time is in the range of 5 to 60 minutes, and by adjusting the temperature and time of the second saturation treatment, the weight crystallinity of the polyamide elastomer during the second saturation treatment is adjusted to be 1.1 to 10%; the T mis the melting temperature of the polyamide elastomer; (3) the saturation treatment system is subjected to pressure release foaming and cooling and shaping in sequence to obtain a polyamide elastomer foam material with a bimodal pore structure. The present invention utilizes foaming gas CO2 to perform saturation treatment on a polyamide elastomer sheet solid sample, wherein the first saturation treatment can achieve melting treatment of the polyamide elastomer and eliminate crystals, and by regulating the temperature and time of the second saturation treatment, the degree of crystallization of the polyamide elastomer is regulated to be 1.1-10%, thereby preparing a polyamide elastomer foam material with a bimodal structure and controllable pore size; and the crystals can play a role of heterogeneous nucleation in the foaming process of the polyamide elastomer, thereby increasing the pore density of the polyamide elastomer foam material, thereby making the polyamide elastomer have a suitable melt strength; because the temperature and pressure of the second saturation treatment are under the supercritical conditions of CO2, the foaming temperature range is widened, not only a polyamide elastomer foam material with a bimodal pore structure is obtained, but also the foaming ratio of the polyamide elastomer foam material is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figures 1 to 6 They are scanning electron microscope images of the polyamide elastomer foam materials with a bimodal structure prepared in Examples 1 to 6 of the present invention;

[0025] Figures 7 to 9 They are scanning electron microscope images of the polyamide elastomer foaming materials with uniform pore structure prepared in Comparative Examples 1 to 3 of the present invention respectively. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing a polyamide elastomer foam material having a bimodal pore structure, comprising the following steps:

[0027] (1) subjecting polyamide elastomer particles to a melt heat-pressing treatment to obtain a polyamide elastomer flake solid sample;

[0028] (2) using a foaming gas CO2 to perform a saturation treatment on the polyamide elastomer sheet solid sample obtained in step (1) to obtain a saturated treatment system;

[0029] The saturation treatment includes two stages: a first saturation treatment and a second saturation treatment; wherein the pressures of the first saturation treatment and the second saturation treatment are independently 10 to 20 MPa;

[0030] The temperature of the first saturation treatment is higher than T m 10-30°C, fully melt the polyamide elastomer sheet solid sample;

[0031] The temperature of the second saturation treatment is lower than T m20°C to 50°C, the second saturation treatment time is in the range of 5 to 60 minutes, and by adjusting the temperature and time of the second saturation treatment, the weight crystallinity of the polyamide elastomer during the second saturation treatment is adjusted to 1.1 to 10%;

[0032] The T m is the melting temperature of the polyamide elastomer;

[0033] (3) The saturated treatment system obtained in step (2) is subjected to pressure release foaming and cooling and shaping in sequence to obtain a polyamide elastomer foam material with a bimodal pore structure.

[0034] The invention subjects polyamide elastomer particles to a melting and hot pressing process to obtain a polyamide elastomer solid sample.

[0035] In the present invention, the hard segment of the polyamide elastomer preferably includes at least one of polyamide 6, polyamide 12, polyamide 10, polyamide 11 and polyamide 1212; the soft segment of the polyamide elastomer preferably includes at least one of polyether, polyester, polyether ester and polycarbonate. The above substances are common soft segments and hard segments of the polyamide elastomer. In the embodiment of the present invention, the polyamide elastomer is PEBA4533 SA 01 particles.

[0036] The present invention has no special provisions on the particle size of the polyamide elastomer particles, and the particle size specifications of conventional commercial products well known to those skilled in the art can be adopted.

[0037] In the present invention, the temperature of the melt hot pressing treatment is preferably higher than T m 20℃~60℃, more preferably higher than T m 25℃~55℃, the T m is the melting temperature of the polyamide elastomer. In the present invention, the pressure of the melt hot pressing treatment is preferably 4 to 15 MPa, more preferably 5 to 14 MPa. In the present invention, the time of the melt hot pressing treatment is preferably 5 to 10 min, more preferably 5 to 7 min. In the present invention, the time of the melt hot pressing treatment refers to the time under the above-mentioned temperature and pressure. The present invention limits the parameters of the melt hot pressing treatment to the above-mentioned range, which is conducive to subjecting the polyamide elastomer particles to melt hot pressing treatment to obtain a polyamide elastomer solid sample, so as to carry out subsequent operations.

[0038] In the present invention, the thickness of the polyamide elastomer solid sample is preferably 1 to 5 mm, more preferably 1 to 4 mm. The present invention controls the thickness of the polyamide elastomer solid sample within the above range, which is beneficial to the cell nucleation and growth in the later foaming process and affects the appearance of the foamed sample.

[0039] After the melt hot pressing treatment is completed, the present invention preferably cools the product of the melt hot pressing treatment to obtain a polyamide elastomer solid sample.

[0040] In the present invention, the cooling method is preferably natural cooling. The present invention has no special provisions for the natural cooling method, that is, "natural cooling" at room temperature is sufficient.

[0041] After obtaining the polyamide elastomer sheet solid sample, the present invention uses foaming gas CO2 to perform saturation treatment on the polyamide elastomer sheet solid sample to obtain a saturated treatment system.

[0042] In the present invention, the saturation process includes two stages: a first saturation process and a second saturation process.

[0043] In the present invention, the T m is the melting temperature of polyamide elastomer.

[0044] In the present invention, the temperature of the first saturation treatment is higher than T m 10~30℃, preferably higher than T m 10~25℃; the pressure of the first saturation treatment is 10~20MPa, preferably 10~18MPa. In the present invention, the time of the first saturation treatment is preferably 5~60min, more preferably 5~30min. The present invention can eliminate the crystal part contained in the solid sample of polyamide elastomer through the first saturation treatment, and fully melt the sample.

[0045] In the present invention, the cooling rate from the temperature of the first saturation treatment to the temperature of the second saturation treatment is preferably 5 to 20°C / min, more preferably 5 to 10°C / min. In the present invention, the temperature of the second saturation treatment is lower than T m 20℃~50℃, preferably below T m30~50℃; the pressure of the second saturation treatment is 10~20MPa, preferably 10~18MPa. In the present invention, the time of the second saturation treatment is preferably 5~60min, more preferably 5~50min. In the present invention, the weight crystallinity of the polyamide elastomer during the second saturation treatment is preferably 1.1~10%. In the present invention, since the temperature and pressure of the second saturation treatment are under the supercritical condition of CO2, the melt crystallization treatment of the polyamide elastomer can be achieved. By regulating the temperature and time of the second saturation treatment, the crystallization process of the polyamide elastomer can be controlled to produce different crystallinities. The formed crystal structure can provide sufficient strength to support the pores, and the expansion ratio can be controlled by controlling the time of the second saturation treatment stage. In addition, the crystal can also act as a nucleating agent as a pore nucleation site, and a bimodal pore structure can be obtained by the difference in pore nucleation and growth in the crystalline region and the amorphous region.

[0046] After the saturated treatment system is obtained, the present invention sequentially performs pressure release foaming and cooling and shaping on the saturated treatment system to obtain a polyamide elastomer foam material with a bimodal pore structure.

[0047] In the present invention, the pressure relief rate of the pressure relief foaming is preferably 5-30 MPa / s, more preferably 5-25 MPa / s. The present invention limits the pressure relief rate of the pressure relief foaming to the above range, which is conducive to obtaining a polyamide elastomer foam material with a bimodal pore structure, and the material has a better morphology and structure.

[0048] In the present invention, the cooling and shaping method is preferably water cooling. The present invention can achieve rapid shaping of the foamed sample by cooling and shaping in a water cooling manner. In the present invention, the temperature of the water in the water cooling is preferably room temperature.

[0049] The present invention also provides a polyamide elastomer foam material having a bimodal pore structure prepared by the preparation method described in the above scheme.

[0050] In the present invention, the polyamide elastomer foam material with a bimodal pore structure includes a plurality of large pores and a plurality of small pores, the average pore diameter of the large pores is 30 to 200 μm, and the average pore diameter of the small pores is 0.6 to 15 μm, wherein the average pore diameter of the large pores is one order of magnitude larger than the average pore diameter of the small pores.

[0051] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The melting temperature T of PEBA4533 SA01 involved in the examples and comparative examples is m is 150℃.

[0053] Example 1

[0054] A method for preparing a polyamide elastomer foam material having a bimodal cell structure, comprising the following steps:

[0055] (1) Putting polyamide elastomer PEBA4533 SA01 particles purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the temperature of the melt hot pressing treatment is set to 180° C., the pressure is 10 MPa, and the temperature and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0056] (2) placing the polyamide elastomer flake solid sample obtained in step (1) into an autoclave, and purging the autoclave with CO2 to remove air and moisture in the autoclave; then increasing the temperature of the autoclave to 170°C and the pressure to 15 MPa (the pressure is provided by the foaming gas CO2) to perform a first saturation treatment, and after reaching the above temperature and pressure, maintaining for 15 minutes to completely melt the polyamide elastomer flake solid sample; then reducing the temperature of the autoclave to 130°C at a rate of 10°C / min, maintaining the pressure of the autoclave at 15 MPa to perform a second saturation treatment, and maintaining at the above temperature and pressure for 10 minutes to obtain a saturated treatment system; wherein, during the second saturation treatment, the weight crystallinity of the polyamide elastomer is 1.10%;

[0057] (3) The saturated treatment system obtained in step (2) is subjected to pressure release and foaming at a rate of 30 MPa / s, and then the autoclave is placed in a room temperature water bath for cooling and shaping to obtain a polyamide elastomer foam material with a bimodal pore structure.

[0058] Example 2

[0059] A method for preparing a polyamide elastomer foam material having a bimodal cell structure, comprising the following steps:

[0060] (1) Putting polyamide elastomer PEBA4533 SA01 particles purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 190° C., the hot pressing pressure is 8 MPa, and the heat and pressure are maintained for 5 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0061] (2) placing the polyamide elastomer solid sample obtained in step (1) into an autoclave, and purging the autoclave with CO2 to remove air and moisture in the autoclave; then increasing the temperature of the autoclave to 180°C and the pressure to 15 MPa (the pressure is provided by the foaming gas CO2) to perform a first saturation treatment, and after reaching the above temperature and pressure, maintaining for 15 minutes to completely melt the polyamide elastomer solid sample; then reducing the temperature of the autoclave to 130°C at a rate of 10°C / min, maintaining the pressure of the autoclave at 15 MPa to perform a second saturation treatment, and maintaining at the above temperature and pressure for 30 minutes to obtain a saturated treatment system; wherein, during the second saturation treatment, the weight crystallinity of the polyamide elastomer is 3.71%;

[0062] (3) The saturated treatment system obtained in step (2) is depressurized at a rate of 30 MPa / s, and then the autoclave is placed in a water bath at room temperature to cool and shape, thereby obtaining a polyamide elastomer foam material with a bimodal pore structure.

[0063] Example 3

[0064] A method for preparing a polyamide elastomer foam material having a bimodal cell structure, comprising the following steps:

[0065] (1) Putting polyamide elastomer PEBA4533 SA01 particles purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 200° C., the hot pressing pressure is 10 MPa, and the heat and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0066] (2) placing the polyamide elastomer solid sample obtained in step (1) into an autoclave, and purging the autoclave with CO2 to remove air and moisture in the autoclave; then increasing the temperature of the autoclave to 190° C. and the pressure to 15 MPa (the pressure is provided by the foaming gas CO2) to perform a first saturation treatment, and after reaching the above temperature and pressure, maintaining for 15 minutes to completely melt the polyamide elastomer solid sample; then reducing the temperature of the autoclave to 130° C. at a rate of 10° C. / min, maintaining the pressure of the autoclave at 15 MPa to perform a second saturation treatment, and maintaining at the above temperature and pressure for 60 minutes to obtain a saturated treatment system; wherein, during the second saturation treatment, the weight crystallinity of the polyamide elastomer is 6.41%;

[0067] (3) The saturated treatment system obtained in step (2) is depressurized at a rate of 30 MPa / s, and then the autoclave is placed in a water bath at room temperature to cool and shape, thereby obtaining a polyamide elastomer foam material with a bimodal pore structure.

[0068] Example 4

[0069] A method for preparing a polyamide elastomer foam material having a bimodal cell structure, comprising the following steps:

[0070] (1) Putting polyamide elastomer PEBA4533 SA01 particles purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 180° C., the hot pressing pressure is 10 MPa, and the heat and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0071] (2) placing the polyamide elastomer solid sample obtained in step (1) into an autoclave, and purging the autoclave with CO2 to remove air and moisture in the autoclave; then increasing the temperature of the autoclave to 170°C and the pressure to 15 MPa (the pressure is provided by the foaming gas CO2) to perform a first saturation treatment, and after reaching the above temperature and pressure, maintaining for 15 minutes to completely melt the polyamide elastomer solid sample; then reducing the temperature of the autoclave to 120°C at a rate of 10°C / min, maintaining the pressure of the autoclave at 15 MPa to perform a second saturation treatment, and maintaining at the above temperature and pressure for 5 minutes to obtain a saturated treatment system; wherein, during the second saturation treatment, the weight crystallinity of the polyamide elastomer is 4.72%;

[0072] (3) The saturated treatment system obtained in step (2) is depressurized at a rate of 30 MPa / s, and then the autoclave is placed in a water bath at room temperature to cool and shape, thereby obtaining a polyamide elastomer foam material with a bimodal pore structure.

[0073] Example 5

[0074] A method for preparing a polyamide elastomer foam material having a bimodal cell structure, comprising the following steps:

[0075] (1) Putting polyamide elastomer PEBA4533 SA01 particles purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 190° C., the hot pressing pressure is 6 MPa, and the heat and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0076] (2) placing the polyamide elastomer solid sample obtained in step (1) into an autoclave, and purging the autoclave with CO2 to remove air and moisture in the autoclave; then increasing the temperature of the autoclave to 170°C and the pressure to 15 MPa (the pressure is provided by the foaming gas CO2) to perform a first saturation treatment, and after reaching the above temperature and pressure, maintaining for 15 minutes to completely melt the polyamide elastomer solid sample; then reducing the temperature of the autoclave to 110°C at a rate of 10°C / min, maintaining the pressure of the autoclave at 15 MPa to perform a second saturation treatment, and maintaining at the above temperature and pressure for 5 minutes to obtain a saturated treatment system; wherein, during the second saturation treatment, the weight crystallinity of the polyamide elastomer is 6.31%;

[0077] (3) The saturated treatment system obtained in step (2) is depressurized at a rate of 30 MPa / s, and then the autoclave is placed in a water bath at room temperature to cool and shape, thereby obtaining a polyamide elastomer foam material with a bimodal pore structure.

[0078] Example 6

[0079] A method for preparing a polyamide elastomer foam material having a bimodal cell structure, comprising the following steps:

[0080] (1) Putting polyamide elastomer PEBA4533 SA01 particles purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 180° C., the hot pressing pressure is 10 MPa, and the heat and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0081] (2) placing the polyamide elastomer solid sample obtained in step (1) into an autoclave, and purging the autoclave with CO2 to remove air and moisture in the autoclave; then increasing the temperature of the autoclave to 170°C and the pressure to 15 MPa (the pressure is provided by the foaming gas CO2) to perform a first saturation treatment, and after reaching the above temperature and pressure, maintaining for 15 minutes to completely melt the polyamide elastomer solid sample; then reducing the temperature of the autoclave to 100°C at a rate of 10°C / min, maintaining the pressure of the autoclave at 15 MPa to perform a second saturation treatment, and maintaining at the above temperature and pressure for 5 minutes to obtain a saturated treatment system; wherein, during the second saturation treatment, the weight crystallinity of the polyamide elastomer is 7.27%;

[0082] (3) The saturated treatment system obtained in step (2) is depressurized at a rate of 30 MPa / s, and then the autoclave is placed in a water bath at room temperature to cool and shape, thereby obtaining a polyamide elastomer foam material with a bimodal pore structure.

[0083] Comparative Example 1

[0084] A method for preparing a polyamide elastomer foam material comprises the following steps:

[0085] (1) Putting polyamide elastomer PEBA4533 SA 01 pellets purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 180° C., the hot pressing pressure is 10 MPa, and the heat and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0086] (2) Put the polyamide elastomer solid sample into an autoclave, and purge the autoclave with CO2 to remove the air and moisture in the autoclave; then increase the temperature of the autoclave to 170°C, and increase the pressure to 15 MPa (the pressure is provided by the foaming gas CO2). After reaching the above temperature and pressure, maintain for 15 minutes to completely melt the polyamide elastomer solid sample; then reduce the temperature of the autoclave to 130°C at a rate of 10°C / min, and maintain the pressure of the autoclave at 15 MPa for 0 minutes;

[0087] (3) The pressure in the autoclave is rapidly released at a rate of 30 MPa / s; and then the autoclave is placed in a water bath to cool and shape, thereby obtaining a polyamide elastomer foam material.

[0088] Comparative Example 2

[0089] A method for preparing a polyamide elastomer foam material, comprising the following steps:

[0090] (1) Putting polyamide elastomer PEBA4533 SA 01 pellets purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 180° C., the hot pressing pressure is 10 MPa, and the heat and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0091] (2) A solid sample of polyamide elastomer is placed in an autoclave, and the autoclave is purged with CO2 to remove air and moisture from the autoclave; then the temperature of the autoclave is increased to 170°C, and the pressure is increased to 15 MPa (the pressure is provided by the foaming gas CO2). After reaching the above temperature and pressure, the pressure is maintained for 15 minutes to completely melt the solid sample of polyamide elastomer; then the temperature of the autoclave is reduced to 130°C at a rate of 10°C / min, and the pressure of the autoclave is maintained at 15 MPa for 5 minutes; the weight crystallinity of the polyamide elastomer is 0.33%.

[0092] (3) The pressure in the autoclave is rapidly released at a rate of 30 MPa / s; and then the autoclave is placed in a water bath to cool and shape, thereby obtaining a polyamide elastomer foam material.

[0093] Comparative Example 3

[0094] A method for preparing a polyamide elastomer foam material, comprising the following steps:

[0095] (1) Putting polyamide elastomer PEBA4533 SA01 particles purchased from Arkema into a mold, and then placing them in a hot press for melt hot pressing treatment; wherein the melt temperature is set to 180° C., the hot pressing pressure is 10 MPa, and the heat and pressure are maintained for 6 minutes, and then naturally cooled to room temperature under normal temperature and pressure conditions to obtain a 4 mm polyamide elastomer sheet solid sample;

[0096] (2) A solid sample of polyamide elastomer is placed in an autoclave, and the autoclave is purged with CO2 to remove air and moisture from the autoclave; then the temperature of the autoclave is increased to 170°C, and the pressure is increased to 15 MPa (the pressure is provided by the foaming gas CO2). After reaching the above temperature and pressure, the conditions are maintained for 15 minutes to allow the solid sample of polyamide elastomer to completely melt; then the temperature of the autoclave is reduced to 140°C at a rate of 10°C / min, and the pressure of the autoclave is maintained at 15 MPa for 20 minutes; the weight crystallinity of the polyamide elastomer is 0.46%.

[0097] (3) The pressure in the autoclave is rapidly released at a rate of 30 MPa / s; and then the autoclave is placed in a water bath to cool and shape, thereby obtaining a polyamide elastomer foam material.

[0098] Effect test

[0099] The polyamide elastomer foam materials obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to electron scanning using a JSM-6360LV scanning electron microscope. The scanning electron microscope images are shown in FIG. Figures 1 to 9 The average cell size and cell structure are characterized by electron microscope images; the expansion ratio is obtained by Archimedes drainage method using ASTM D792-00, and the test results are shown in Table 1.

[0100] Table 1 Test results of polyamide elastomer foam materials obtained in Examples 1 to 6 and Comparative Examples 1 to 3

[0101]

[0102] Depend on Figures 1 to 9 As can be seen from the data in Table 1, the present invention can prepare a polyamide elastomer foam material with a bimodal pore structure with controllable size by regulating the temperature and time of the second saturation treatment (the second stage of melt isothermal crystallization).

[0103] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a polyamide elastomer foam material having a bimodal cell structure, characterized in that: The following steps are involved: (1) subjecting polyamide elastomer particles to a melt heat-pressing treatment to obtain a polyamide elastomer flake solid sample; (2) using a foaming gas CO2 to perform a saturation treatment on the polyamide elastomer sheet solid sample obtained in step (1) to obtain a saturated treatment system; The saturation treatment includes two stages: a first saturation treatment and a second saturation treatment; wherein the pressures of the first saturation treatment and the second saturation treatment are independently 10 to 20 MPa; The temperature of the first saturation treatment is higher than T m 10-30°C, fully melt the polyamide elastomer sheet solid sample; The temperature of the second saturation treatment is lower than T m 20°C to 50°C, the second saturation treatment time is in the range of 5 to 60 minutes, and by adjusting the temperature and time of the second saturation treatment, the weight crystallinity of the polyamide elastomer during the second saturation treatment is adjusted to 1.1 to 10%; The T m is the melting temperature of the polyamide elastomer; (3) The saturated treatment system obtained in step (2) is subjected to pressure release foaming and cooling and shaping in sequence to obtain a polyamide elastomer foam material with a bimodal pore structure.

2. The preparation method according to claim 1, characterized in that: In the step (1), the hard segment of the polyamide elastomer includes at least one of polyamide 6, polyamide 12, polyamide 10, polyamide 11 and polyamide 1212, and the soft segment of the polyamide elastomer includes at least one of polyether, polyester, polyether ester and polycarbonate.

3. The preparation method according to claim 1, characterized in that: The temperature of the melt hot pressing treatment in step (1) is higher than T m The temperature is 20°C to 60°C, the pressure of the melt hot pressing treatment is 4 to 15 MPa, and the time of the melt hot pressing treatment is 5 to 10 minutes.

4. The preparation method according to claim 1, characterized in that: In the step (1), the thickness of the polyamide elastomer sheet solid sample is 1 to 5 mm.

5. The preparation method according to claim 1, characterized in that: In the step (2), the cooling rate from the temperature of the first saturation treatment to the temperature of the second saturation treatment is 5 to 20° C. / min.

6. The preparation method according to claim 1, characterized in that: The time of the first saturation treatment in step (2) is 5 to 60 minutes.

7. The preparation method according to claim 1, characterized in that: The pressure relief rate of the pressure relief foaming in step (3) is 5 to 30 MPa / s.

8. The preparation method according to claim 1, characterized in that: The cooling and shaping method in step (3) is water cooling.

9. The polyamide elastomer foam material having a bimodal cell structure prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The polyamide elastomer foam material with a bimodal pore structure includes a plurality of large pores and a plurality of small pores, wherein the average pore diameter of the large pores is 30 to 200 μm, and the average pore diameter of the small pores is 0.6 to 15 μm, wherein the average pore diameter of the large pores is one order of magnitude larger than the average pore diameter of the small pores.

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