A supercritical sandwich polyaryletherketone foamed board and preparation method thereof

Abstract

The present invention provides a polyaryletherketone foamed plate, the polyaryletherketone foamed plate comprises a middle foaming layer and upper and lower foaming layers; the middle foaming layer has different densities from the upper and lower foaming layers; the middle foaming layer has different foaming ratios from the upper and lower foaming layers; the middle foaming layer has different pore diameters from the upper and lower foaming layers. The present invention designs a sandwich polyaryletherketone foamed plate with a specific structure, which is divided into a middle foaming layer and upper and lower foaming layers. The present invention utilizes a sandwich structure with different density distributions, so that at the same density, the sandwich structure material foam has comprehensive mechanical properties and comprehensive mechanical properties such as very high stiffness and bending strength. Moreover, the polyaryletherketone foamed plate provided by the present invention uses only the commonly used polyaryletherketone resin on the market as a raw material, so as to obtain a polyaryletherketone foamed plate with excellent performance, and the foaming process is green and environmentally friendly, with a wide range of applications, which is conducive to the realization of industrial-scale production and application.

Description

Technical Field

[0001] The invention belongs to the technical field of polyaryletherketone foamed boards, and relates to a polyaryletherketone foamed board and a preparation method thereof, and in particular to a supercritical sandwich polyaryletherketone foamed board and a preparation method thereof. Background Art

[0002] Foam plastics are a type of polymer material formed by a large number of gas micropores dispersed in solid plastics. They have the characteristics of light weight, heat insulation, sound absorption, shock absorption, and dielectric properties are better than those of base resins. They are widely used. Almost all kinds of plastics can be made into foam plastics, and foam molding has become an important field in plastic processing. Compared with pure plastics, foam plastics have many excellent properties, such as light weight, high specific strength, ability to absorb impact loads, good heat insulation and sound insulation, etc. Therefore, they have been widely used in industry, agriculture, construction, transportation and other fields.

[0003] Structural foam material refers to a sandwich structure of various composite materials, which is mainly used to increase rigidity and reduce weight. Structural foam material is a kind of application of foam material. It is a sandwich structure applied to various composite materials, which is mainly used to increase rigidity and reduce weight. It has excellent specific rigidity and specific strength. It has mechanical properties such as compression, tension, shear, bending, and excellent fatigue resistance and impact resistance. In addition, it also has the characteristics of low water absorption and good sound insulation and heat insulation, making it an ideal material for fields requiring high strength and low density. It is widely used in wind power generation, rail transportation, ships, aerospace, building energy conservation and other fields.

[0004] However, the structural foams currently on the market include rigid polyurethane, rigid polyvinyl chloride, and polymethacrylimide (PMI) foam. In particular, only PMI foam has relatively high performance and usage among high-temperature resistant foams. There is no similar high-temperature resistant structural foam on the market that can compare with PMI.

[0005] Therefore, how to find another type of highly heat-resistant structural foam to broaden the application depth and breadth of structural foam is of great significance and is also one of the urgent issues that many R&D manufacturers and front-line researchers need to solve. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a polyaryletherketone foamed sheet and a preparation method thereof, in particular, a supercritical sandwich polyaryletherketone foamed sheet. The polyaryletherketone foamed sheet provided by the present invention uses only a general grade of polylactic acid as a raw material to obtain a polyaryletherketone foam with a moderate overall density, so that the overall density can be comparable to that of PMI foam, and the process is simple and easy to control, which is conducive to industrial-scale production and application. It also provides a new idea and method for the development of such a supercritical sandwich foam.

[0007] The present invention provides a polyaryletherketone foamed plate, the polyaryletherketone foamed plate comprising a middle foaming layer and upper and lower foaming layers;

[0008] The middle foaming layer has different densities from the upper and lower foaming layers;

[0009] The middle foaming layer and the upper and lower foaming layers have different foaming ratios;

[0010] The middle foaming layer and the upper and lower foaming layers have different cell diameters.

[0011] Preferably, the overall density of the foamed board is 50 to 200 kg / m 3 ;

[0012] The density of the middle foaming layer is 100-200 kg / m 3 ;

[0013] The density of the upper and lower foaming layers is 50-100 kg / m 3 ;

[0014] The cells are closed-cell structures.

[0015] Preferably, the overall foaming ratio of the foamed board is 5 to 20 times;

[0016] The foaming ratio of the middle foaming layer is 5 to 10 times;

[0017] The foaming ratio of the upper and lower foaming layers is 10 to 20 times;

[0018] The polyaryletherketone foamed plate is an integrated foamed material.

[0019] Preferably, the pore diameter of the foamed plate as a whole is 50 to 300 μm;

[0020] The pore diameter of the middle foaming layer is 50 to 200 μm;

[0021] The pore diameters of the upper and lower foaming layers are 50 to 300 μm;

[0022] The polyaryletherketone foamed sheet is obtained by foaming a single polyaryletherketone resin sheet;

[0023] The foaming method includes double foaming of supercritical fluid.

[0024] Preferably, the polyaryletherketone foamed sheet has a sandwich structure;

[0025] The thickness of the polyaryletherketone foamed plate is 10 to 100 mm;

[0026] The oriented dimension of the polyaryletherketone sheet is 100 to 1000 mm;

[0027] The polyaryletherketone foamed sheet is a foamed sheet that is not formed by pressing, not formed by bonding, and not formed by combining multiple materials.

[0028] The polyaryletherketone foamed board is a structural foam board used for structural core material.

[0029] The present invention also provides a method for preparing a polyaryletherketone foamed plate, comprising the following steps:

[0030] 1) placing a polyaryletherketone sheet in a mold cavity, filling it with a supercritical fluid at a first temperature, maintaining pressure to infiltrate after reaching equilibrium, and then releasing pressure to foam to obtain a polyaryletherketone foamed embryo sheet;

[0031] 2) placing the polyaryletherketone foamed embryo plate obtained in the above step into a mold cavity, and again filling it with supercritical fluid at a second temperature, and after reaching equilibrium, again maintaining pressure for infiltration, and then releasing pressure for foaming to obtain a polyaryletherketone foamed plate.

[0032] Preferably, the polyaryletherketone sheet is obtained by compression molding polyaryletherketone resin using a high-temperature vulcanizer;

[0033] The viscosity of the polyaryletherketone resin is 0.3 to 1.2 dl / g;

[0034] The glass transition temperature of the polyaryletherketone resin is 230 to 280°C;

[0035] The compression molding process comprises the following steps:

[0036] Preheat at 220-250℃, compact and exhaust at 0.5-2Mpa for 10-15min, heat to 260-280℃, maintain for 20-30min, maintain surface pressure at 2-5Mpa, then mold at 300-320℃ and 5-8Mpa for 30-60min.

[0037] Preferably, the thickness of the polyaryletherketone sheet is 3 to 10 mm;

[0038] The supercritical fluid includes supercritical N2 and / or supercritical CO2;

[0039] The pressure of the supercritical fluid is 7-20 MPa;

[0040] The second temperature is higher than the first temperature.

[0041] Preferably, the first temperature is 250-260°C;

[0042] The second temperature is 270-280°C;

[0043] The immersion time of the pressure-maintaining penetration is 120 to 180 minutes;

[0044] The pressure of the pressure-maintaining penetration is 10-20 MPa.

[0045] Preferably, the immersion time for the second pressure-maintaining infiltration is 30 to 90 minutes;

[0046] The pressure of the second pressure-maintaining penetration is 7 to 10 MPa;

[0047] The pressure after the pressure relief is normal pressure;

[0048] The pressure relief rate is 10-100 MPa / s.

[0049] The present invention provides a polyaryletherketone foamed plate, the polyaryletherketone foamed plate comprises an intermediate foaming layer and upper and lower foaming layers; the intermediate foaming layer has different densities from the upper and lower foaming layers; the intermediate foaming layer has different foaming ratios from the upper and lower foaming layers; the intermediate foaming layer has different pore diameters from the upper and lower foaming layers. Compared with the prior art, the present invention is aimed at the fact that the existing structural foam types are scarce, especially the foam core material in terms of high temperature resistance is a PMI foam, and other foam materials are difficult to reach the same level as PMI foam in terms of performance, density and usage. The present invention believes that thermoplastic high-performance polyaryletherketone (PEK) has excellent characteristics such as flame retardancy, high temperature resistance, radiation resistance, and low dielectric. Under the action of supercritical fluid, after decompression foaming, uniform and delicate pores can be obtained. Although the prior art also uses this method to prepare polyaryletherketone foam, the foam in the existing process is of uniform structure and consistent density, and at the same density, there is still a problem that the performance of PEK foam cannot catch up with PMI foam.

[0050] In this regard, the present invention creatively designs a polyaryletherketone foamed board with a specific structure, which is a sandwich polyaryletherketone foamed board, which is divided into a middle foaming layer and upper and lower foaming layers, and the density of the middle foaming layer is 100-200kg / m 3 The density of the upper and lower layers is 50-100 kg / m 3. The present invention utilizes sandwich structures with different density distributions, so that at the same density, the sandwich structure material foam has comprehensive mechanical properties and comprehensive mechanical properties such as very high stiffness and bending strength. Moreover, the polyaryletherketone foamed board provided by the present invention only uses the commonly used polyaryletherketone resin (board) on the market as a raw material to obtain a polyaryletherketone foamed board with excellent performance. The preparation method of the polyaryletherketone foamed board provided by the present invention adopts a supercritical fluid foaming method combined with a two-step impregnation foaming process, which is divided into secondary impregnation with supercritical fluid and secondary foaming, so as to form a special integrated sandwich structure, the core material has a high density, the upper and lower layers have a low density, and the overall density of the polyaryletherketone foam is moderate, so that the overall density can be comparable to PMI foam, which provides a new idea and method for the development of such supercritical sandwich foam.

[0051] The sandwich polyaryletherketone foamed board provided by the present invention uses only one piece of polyaryletherketone raw material board and adopts a step-by-step impregnation method to obtain a polyaryletherketone foamed board with excellent performance. The preparation method provided by the present invention, combined with the two-step supercritical infiltration method, can realize the preparation of sandwich polyaryletherketone foamed boards; and by controlling the temperature and time of supercritical infiltration, the density of the upper and lower layers and the middle layer can be controlled, thereby obtaining a foam material with excellent comprehensive performance, especially excellent mechanical properties, which is suitable as a structural core material of composite materials. The polyaryletherketone foamed board prepared by the present invention can be used for a long time at -50 to 250°C, and the foaming process is green and environmentally friendly, with a wide range of applications, which is conducive to the realization of industrial-scale production and application.

[0052] The experimental results show that the preparation method provided by the present invention, combined with the two-step supercritical infiltration method, can realize the preparation of sandwich polyaryletherketone foamed board. Moreover, various forms of density combinations can be obtained. By controlling the temperature and time of supercritical infiltration, the density of the upper and lower layers and the middle layer can be controlled, thereby obtaining foam with excellent comprehensive performance, especially mechanical properties. The prepared foamed board has a large size, with a length and width of 100 to 1000 mm and a thickness of 10 to 100 mm; the pore diameter is 100 to 300 μm; the foaming ratio reaches 5 to 20 times, the compression strength can reach 2.5 MPa, the tensile strength can reach 3 MPa, and the bending strength can reach 2 MPa. It is a foam core material with excellent comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a real photo of the cross section of the supercritical sandwich polyaryletherketone foamed board prepared in the present invention. DETAILED DESCRIPTION

[0054] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention.

[0055] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0056] There is no particular restriction on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials with conventional purity requirements in the field of polyaryletherketone foaming material preparation.

[0057] The brands and abbreviations of all raw materials of the present invention are conventional brands and abbreviations in the art. Each brand and abbreviation is clear and definite in the field of its related use. Those skilled in the art can purchase them from the market or prepare them by conventional methods according to the brands, abbreviations and corresponding uses.

[0058] The present invention provides a polyaryletherketone foamed plate, the polyaryletherketone foamed plate comprising a middle foaming layer and upper and lower foaming layers;

[0059] The middle foaming layer has different densities from the upper and lower foaming layers;

[0060] The middle foaming layer and the upper and lower foaming layers have different foaming ratios;

[0061] The middle foaming layer and the upper and lower foaming layers have different cell diameters.

[0062] In the present invention, the middle foam layer has different densities from the upper and lower foam layers. Specifically, the density of the middle foam layer is preferably greater than the density of the upper and lower foam layers.

[0063] In the present invention, the middle foam layer has different foaming ratios from the upper and lower foam layers. Specifically, the foaming ratio of the middle foam layer is preferably smaller than the foaming ratios of the upper and lower foam layers.

[0064] In the present invention, the middle foam layer and the upper and lower foam layers have different pore diameters. Specifically, the pore diameter of the middle foam layer is preferably smaller than the pore diameters of the upper and lower foam layers.

[0065] In the present invention, the overall density of the foamed board is preferably 50 to 200 kg / m 3 , more preferably 80 to 170 kg / m 3 , more preferably 110 to 140 kg / m 3 .

[0066] In the present invention, the density of the intermediate foam layer is preferably 120 to 200 kg / m 3 , more preferably 120 to 180 kg / m 3 , more preferably 140 to 160 kg / m 3 .

[0067] In the present invention, the density of the upper and lower foaming layers is preferably 50 to 100 kg / m 3 , more preferably 60 to 90 kg / m 3 , more preferably 70 to 80 kg / m 3 .

[0068] In the present invention, the cells are preferably closed-cell structures.

[0069] In the present invention, the foaming ratio of the foamed plate as a whole is preferably 5 to 20 times, more preferably 8 to 17 times, and more preferably 11 to 14 kg / m 3 .

[0070] In the present invention, the foaming ratio of the intermediate foam layer is preferably 5 to 10 times, more preferably 6 to 9 times, and more preferably 7 to 8 times.

[0071] In the present invention, the foaming ratio of the upper and lower foaming layers is preferably 10 to 20 times, more preferably 12 to 18 times, and more preferably 14 to 16 times.

[0072] In the present invention, the polyaryletherketone foamed board is preferably an integral foamed material.

[0073] In the present invention, the pore diameter of the entire foamed plate is preferably 50 to 300 μm, more preferably 100 to 250 μm, and even more preferably 150 to 200 μm.

[0074] In the present invention, the cell diameter of the intermediate foam layer is preferably 50 to 200 μm, more preferably 70 to 180 μm, and even more preferably 100 to 150 μm.

[0075] In the present invention, the cell diameter of the upper and lower foaming layers is preferably 50 to 300 μm, more preferably 51 to 300 μm, more preferably 100 to 250 μm, and more preferably 150 to 200 μm.

[0076] In the present invention, the polyaryletherketone foamed sheet is preferably obtained by foaming a single polyaryletherketone resin sheet.

[0077] In the present invention, the foaming method preferably includes double foaming of supercritical fluid.

[0078] In the present invention, the polyaryletherketone foamed board preferably has a sandwich structure.

[0079] In the present invention, the thickness of the polyaryletherketone foamed plate is preferably 10 to 100 mm, more preferably 30 to 80 mm, and even more preferably 50 to 60 mm.

[0080] In the present invention, the oriented dimension of the polyaryletherketone sheet is preferably 100 to 1000 mm, more preferably 300 to 800 mm, and even more preferably 500 to 600 mm.

[0081] In the present invention, the polyaryletherketone foamed board is preferably a foamed board that is not pressed, bonded or assembled from multiple materials, more preferably a foamed board that is not pressed, bonded or assembled from multiple materials.

[0082] In the present invention, the polyaryletherketone foamed board is preferably a structural foam board, that is, a structural foam board used for structural core materials.

[0083] The present invention provides a sandwich polyaryletherketone foamed plate, wherein the foaming ratio of the sandwich polyaryletherketone foamed plate is 5 to 20 times;

[0084] The diameter of the pores of the polyaryletherketone foamed plate is 50 to 300 μm.

[0085] Specifically, the polyaryletherketone foamed plate has a thickness of 10 to 100 mm.

[0086] Specifically, the pores are closed-cell structures.

[0087] Specifically, the density of the polyaryletherketone foamed plate is 50 to 200 kg / m 3 ;

[0088] Specifically, the density of the upper and lower layers of the polyaryletherketone foamed plate is 50 to 100 kg / m 3 ;

[0089] Specifically, the density of the middle layer of the polyaryletherketone foamed plate is 100 to 200 kg / m 3 .

[0090] See also Figure 1 , Figure 1 This is a real photo of the cross section of the supercritical sandwich polyaryletherketone foamed board prepared in the present invention.

[0091] The present invention provides a method for preparing a polyaryletherketone foamed plate, comprising the following steps:

[0092] 1) placing a polyaryletherketone sheet in a mold cavity, filling it with a supercritical fluid at a first temperature, maintaining pressure to infiltrate after reaching equilibrium, and then releasing pressure to foam to obtain a polyaryletherketone foamed embryo sheet;

[0093] 2) placing the polyaryletherketone foamed embryo plate obtained in the above step into a mold cavity, and again filling it with supercritical fluid at a second temperature, and after reaching equilibrium, again maintaining pressure for infiltration, and then releasing pressure for foaming to obtain a polyaryletherketone foamed plate.

[0094] In the present invention, after equilibrium, a polymer-supercritical fluid homogeneous system is formed.

[0095] The invention first places a polyaryletherketone sheet in a mold cavity, fills in a supercritical fluid at a first temperature, maintains pressure for penetration after reaching equilibrium, and then releases pressure for foaming to obtain a polyaryletherketone foamed embryo plate.

[0096] In the present invention, the polyaryletherketone sheet is preferably obtained by compression molding polyaryletherketone resin in a high-temperature vulcanizer.

[0097] In the present invention, the viscosity of the polyaryletherketone resin is preferably 0.3 to 1.2 dl / g, more preferably 0.5 to 1.0 dl / g, and even more preferably 0.7 to 0.8 dl / g.

[0098] In the present invention, the glass transition temperature of the polyaryletherketone resin is preferably 230 to 280°C, more preferably 240 to 270°C, and even more preferably 250 to 260°C.

[0099] In the present invention, the compression molding process preferably comprises the following steps:

[0100] Preheat at 220-250℃, compact and exhaust at 0.5-2Mpa for 10-15min, heat to 260-280℃, maintain for 20-30min, maintain surface pressure at 2-5Mpa, then mold at 300-320℃ and 5-8Mpa for 30-60min.

[0101] In the present invention, the thickness of the polyaryletherketone sheet is preferably 3 to 10 mm, more preferably 4 to 9 mm, more preferably 5 to 8 mm, and more preferably 6 to 7 mm.

[0102] In the present invention, the supercritical fluid preferably includes supercritical N2 and / or supercritical CO2, more preferably supercritical N2 or supercritical CO2.

[0103] In the present invention, the pressure of the supercritical fluid is preferably 7 to 20 MPa, more preferably 10 to 17 MPa, and even more preferably 13 to 14 MPa.

[0104] In the present invention, the first temperature is preferably 250-260°C, more preferably 252-258°C, and more preferably 254-256°C.

[0105] In the present invention, the immersion time for the pressure-maintaining penetration is preferably 120 to 180 min, more preferably 130 to 170 min, and even more preferably 140 to 160 min.

[0106] In the present invention, the pressure of the pressure-maintaining penetration is preferably 10 to 20 MPa, more preferably 12 to 18 MPa, and more preferably 14 to 16 MPa.

[0107] In the present invention, the pressure after decompression is preferably normal pressure.

[0108] In the present invention, the pressure relief rate is preferably 10 to 100 MPa / s, more preferably 30 to 80 MPa / s, and more preferably 50 to 60 MPa / s.

[0109] The present invention places the polyaryletherketone foamed embryo plate obtained in the above steps into a mold cavity, and again fills in a supercritical fluid at a second temperature. After reaching equilibrium, the polyaryletherketone foamed plate is again infiltrated under pressure, and then released to foam to obtain the polyaryletherketone foamed plate.

[0110] In the present invention, the second temperature is preferably higher than the first temperature.

[0111] In the present invention, the second temperature is preferably 270-280°C, more preferably 272-278°C, and even more preferably 274-276°C.

[0112] In the present invention, the immersion time for the second pressure-maintaining infiltration is preferably 30 to 90 minutes, more preferably 40 to 80 minutes, and even more preferably 50 to 70 minutes.

[0113] In the present invention, the pressure of the second pressure-maintaining infiltration is preferably 7 to 10 MPa, more preferably 7.5 to 9.5 MPa, and more preferably 8 to 9 MPa.

[0114] The present invention is to complete and refine the overall preparation process, and better improve the comprehensive performance of the polyaryletherketone foamed board. The preparation method of the sandwich polyaryletherketone foamed board can specifically be the following steps:

[0115] 1) The polyaryletherketone resin is molded by a high temperature vulcanizer to form a base plate with a thickness of 3 to 10 mm.

[0116] 2) placing the polyaryletherketone original sheet in a mold cavity at a first temperature, filling it with a supercritical fluid, and obtaining a polymer-supercritical fluid homogeneous system after reaching equilibrium;

[0117] 3) By controlling the pressure change of the system, the pressure is released quickly for foaming to obtain a polyaryletherketone foamed embryo board.

[0118] 4) placing the polyaryletherketone foamed embryo plate in the mold cavity, and filling it with a supercritical fluid at a second temperature to obtain a polymer-supercritical fluid homogeneous system after reaching equilibrium;

[0119] 5) The polyaryletherketone foamed board is obtained by controlling the pressure change of the system and rapidly releasing the pressure to foam.

[0120] Specifically, the polyaryletherketone resin has a viscosity of 0.3 to 1.2 dl / g.

[0121] Specifically, the glass transition temperature of the polyaryletherketone resin is 230-280°C.

[0122] Specifically, the molding process in step 1 is preheating at 220-250°C, compacting and exhausting under the action of 0.5-2Mpa for 10-15min, heating to 260-280°C, maintaining for 20-30min, maintaining the surface pressure at 2-5Mpa, and then molding at 300-320°C, 5-8Mpa. Molding for 30-60min, and finally cooling and demolding to make an original plate with a thickness of 3-10mm.

[0123] Specifically, the second temperature is higher than the first temperature.

[0124] The first temperature is 250-260°C.

[0125] Specifically, the second temperature is 270-280°C.

[0126] Specifically, the supercritical fluid includes supercritical N2 and / or supercritical CO2.

[0127] Specifically, the pressure of the supercritical fluid is 7-20 MPa.

[0128] Specifically, the immersion time at the first temperature is 120-180 minutes, and the pressure is 10-20 MPa.

[0129] Specifically, the immersion time at the second temperature is 30 to 90 minutes, and the pressure is 7 to 10 MPa.

[0130] Specifically, the control pressure changes, the pressure is released quickly to produce foam, and the pressure after the pressure release is normal pressure.

[0131] Specifically, the pressure relief rate is 10-100 MPa / s.

[0132] The above steps of the present invention provide a supercritical sandwich polyaryletherketone foamed board and a preparation method thereof. The polyaryletherketone foamed board with a specific structure is a sandwich polyaryletherketone foamed board, which is divided into a middle foaming layer and upper and lower foaming layers. The density of the middle foaming layer is 100-200 kg / m 3 The density of the upper and lower layers is 50-100 kg / m 3. The present invention utilizes sandwich structures with different density distributions, so that at the same density, the sandwich structure material foam has comprehensive mechanical properties and comprehensive mechanical properties such as very high stiffness and bending strength. Moreover, the polyaryletherketone foamed board provided by the present invention only uses the commonly used polyaryletherketone resin (board) on the market as a raw material to obtain a polyaryletherketone foamed board with excellent performance. The preparation method of the polyaryletherketone foamed board provided by the present invention adopts a supercritical fluid foaming method combined with a two-step impregnation foaming process, which is divided into secondary impregnation with supercritical fluid and secondary foaming, so as to form a special integrated sandwich structure, the core material has a high density, the upper and lower layers have a low density, and the overall density of the polyaryletherketone foam is moderate, so that the overall density can be comparable to PMI foam, which provides a new idea and method for the development of such supercritical sandwich foam.

[0133] The sandwich polyaryletherketone foamed board provided by the present invention uses only one piece of polyaryletherketone raw material board and adopts a step-by-step impregnation method to obtain a polyaryletherketone foamed board with excellent performance. The preparation method provided by the present invention, combined with the two-step supercritical infiltration method, can realize the preparation of sandwich polyaryletherketone foamed boards; and by controlling the temperature and time of supercritical infiltration, the density of the upper and lower layers and the middle layer can be controlled, thereby obtaining a foam material with excellent comprehensive performance, especially excellent mechanical properties, which is suitable as a structural core material of composite materials. The polyaryletherketone foamed board prepared by the present invention can be used for a long time at -50 to 250°C, and the foaming process is green and environmentally friendly, with a wide range of applications, which is conducive to the realization of industrial-scale production and application.

[0134] The experimental results show that the preparation method provided by the present invention, combined with the two-step supercritical infiltration method, can realize the preparation of sandwich polyaryletherketone foamed board. Moreover, various forms of density combinations can be obtained. By controlling the temperature and time of supercritical infiltration, the density of the upper and lower layers and the middle layer can be controlled, thereby obtaining foam with excellent comprehensive performance, especially mechanical properties. The foamed board obtained is large in size, with a length and width of 100 to 1000 mm and a thickness of 10 to 100 mm; the pore diameter is 100 to 300 μm; the foaming ratio reaches 5 to 20 times, the compression strength can reach 3.4 MPa, the tensile strength can reach 3.6 MPa, and the bending strength can reach 3.8 MPa. It is a foam core material with excellent comprehensive performance.

[0135] In order to further illustrate the present invention, a polyaryletherketone foamed board and a preparation method thereof provided by the present invention are described in detail below in combination with embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following embodiments.

[0136] Example 1

[0137] First, the polyaryletherketone resin is preheated at 220°C in the mold, and compacted and exhausted under the action of 1Mpa for 10 minutes. The temperature is then raised to 280°C and maintained for 20 minutes. The surface pressure is maintained at 2Mpa, and then molded at 300°C and 8Mpa for 60 minutes. Finally, it is cooled and demolded to form a 3mm thick original plate.

[0138] Then, in the foaming mold cavity, the temperature is kept constant at 250°C. After replacing the air in the mold cavity, carbon dioxide is filled in to a supercritical state, the pressure is controlled at 10 MPa, and after maintaining the pressure and penetrating for 120 minutes, the pressure is quickly released to normal pressure to obtain a foamed embryo board.

[0139] Next, place the foamed embryo board into the foaming mold, raise the temperature to T2, T2 is selected to be 275°C, replace the air in the mold cavity, fill it with carbon dioxide to a supercritical state, control the pressure at 8MPa, and maintain it for 30 minutes.

[0140] Finally, the pressure in the mold cavity is released to normal pressure through the pneumatic ball valve. The pressure release rate is controlled between 20 and 50 MPa / s by adjusting the diameter of the pneumatic ball valve. A sandwich polyaryletherketone foamed sheet is obtained.

[0141] Example 2

[0142] First, the polyaryletherketone resin is preheated at 250°C in the mold, compacted and exhausted under the action of 0.5Mpa for 10 minutes, then heated to 280°C and maintained for 30 minutes, with the surface pressure maintained at 5Mpa, and then molded at 320°C and 8Mpa for 50 minutes. Finally, it is cooled and demolded to make an original plate with a thickness of 5mm.

[0143] Then, in the foaming mold cavity, the temperature is kept constant at 260°C. After replacing the air in the mold cavity, carbon dioxide is filled in to a supercritical state, the pressure is controlled at 12 MPa, and after maintaining the pressure and penetrating for 150 minutes, the pressure is quickly released to normal pressure to obtain a foamed embryo board.

[0144] Next, place the foamed embryo board into the foaming mold, raise the temperature to T2, T2 is selected to be 280°C, replace the air in the mold cavity, fill it with carbon dioxide to a supercritical state, control the pressure at 10MPa, and maintain it for 40 minutes.

[0145] Finally, the pressure in the mold cavity is released to normal pressure through the pneumatic ball valve. The pressure release rate is controlled between 20 and 50 MPa / s by adjusting the diameter of the pneumatic ball valve. A sandwich polyaryletherketone foamed sheet is obtained.

[0146] Example 3

[0147] First, the polyaryletherketone resin is preheated at 250°C in the mold, compacted and exhausted under the action of 1.5Mpa for 10 minutes, then heated to 280°C and maintained for 30 minutes, with a surface pressure of 5Mpa, and then molded at 300°C and 8Mpa for 60 minutes. Finally, it is cooled and demolded to make an original plate with a thickness of 5mm.

[0148] Then, in the foaming mold cavity, the temperature is kept constant at 260°C. After replacing the air in the mold cavity, carbon dioxide is filled in to a supercritical state, the pressure is controlled at 15MPa, and after maintaining the pressure and penetrating for 180 minutes, the pressure is quickly released to normal pressure to obtain a foamed embryo board.

[0149] Next, place the foamed embryo board into the foaming mold, raise the temperature to T2, T2 is selected to be 280°C, replace the air in the mold cavity, fill it with carbon dioxide to a supercritical state, control the pressure at 10MPa, and maintain it for 90 minutes.

[0150] Finally, the pressure in the mold cavity is released to normal pressure through the pneumatic ball valve. The pressure release rate is controlled between 20 and 50 MPa / s by adjusting the diameter of the pneumatic ball valve. A sandwich polyaryletherketone foamed sheet is obtained.

[0151] The performance of the sandwich polyaryletherketone foamed board prepared in the embodiment of the present invention was tested.

[0152] See Table 1, which is a comparison of the performance test results of the sandwich polyaryletherketone foamed board prepared by the present invention and commercially available PMI.

[0153] Table 1

[0154]

[0155]

[0156] It can be seen from Table 1 that the sandwich polyaryletherketone foamed board provided by the present invention has high mechanical properties. When the density of boards of the same thickness is not much different, it can be equivalent to PMI and can meet the use requirements of structural core materials with high temperature bearing.

[0157] The above is a detailed introduction to a supercritical sandwich polyaryletherketone foamed board and a preparation method thereof provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and its core ideas of the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the textual expression of the claims, or if they include equivalent structural elements that are not substantially different from the textual expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A polyaryletherketone foamed sheet, characterized in that: The polyaryletherketone foamed plate comprises a middle foaming layer and upper and lower foaming layers; The middle foaming layer has different densities from the upper and lower foaming layers; The middle foaming layer and the upper and lower foaming layers have different foaming ratios; The middle foaming layer and the upper and lower foaming layers have different cell diameters; The density of the middle foaming layer is 100-200 kg / m 3 ; The density of the upper and lower foaming layers is 50-100 kg / m 3 The foaming ratio of the middle foaming layer is 5 to 10 times; The foaming ratios of the upper and lower foaming layers are 10 to 20 times respectively; The polyaryletherketone foamed plate has a sandwich structure; The pores are closed-cell structures; The polyaryletherketone foamed sheet is obtained by foaming a single polyaryletherketone resin sheet; The preparation method of the polyaryletherketone foamed plate comprises the following steps: 1) placing a polyaryletherketone sheet in a mold cavity, filling it with a supercritical fluid at a first temperature, maintaining pressure to infiltrate after reaching equilibrium, and then releasing pressure to foam to obtain a polyaryletherketone foamed embryo sheet; The polyaryletherketone sheet is obtained by molding polyaryletherketone resin in a high-temperature vulcanizer; The viscosity of the polyaryletherketone resin is 0.3-1.2dl / g; The glass transition temperature of the polyaryletherketone resin is 230-280°C; The compression molding process comprises the following steps: Preheat at 220~250℃, compact and exhaust at 0.5-2Mpa for 10~15min, heat to 260~280℃, maintain for 20~30min, maintain surface pressure at 2~5mpa, then mold at 300~320℃, mold pressure at 5~8Mpa for 30~60min; 2) placing the polyaryletherketone foamed embryo plate obtained in the above step in a mold cavity, and again filling the mold cavity with a supercritical fluid at a second temperature, and after reaching equilibrium, again maintaining pressure for infiltration, and then releasing pressure for foaming to obtain a polyaryletherketone foamed plate; The second temperature is higher than the first temperature; The first temperature is 250-260°C; The second temperature is 270-280°C.

2. The polyaryletherketone foamed plate according to claim 1, characterized in that: The overall density of the foamed board is 50-200 kg / m 3 .

3. The polyaryletherketone foamed plate according to claim 1, characterized in that: The overall foaming ratio of the foamed sheet is 5 to 20 times; The polyaryletherketone foamed plate is an integrated foamed material.

4. The polyaryletherketone foamed plate according to claim 1, characterized in that: The overall pore diameter of the foamed sheet is 50-300 μm; The pore diameter of the middle foaming layer is 50-200 μm; The diameter of the pores of the upper and lower foaming layers is 50-300 μm.

5. The polyaryletherketone foamed plate according to claim 1, characterized in that: The foaming method includes double foaming of supercritical fluid.

6. The polyaryletherketone foamed plate according to claim 1, characterized in that: The thickness of the polyaryletherketone foamed plate is 10-100 mm; The oriented dimension of the polyaryletherketone sheet is 100-1000 mm.

7. The polyaryletherketone foamed plate according to claim 1, characterized in that: The polyaryletherketone foamed sheet is a foamed sheet that is not formed by pressing, not formed by bonding, and not formed by combining multiple materials. The polyaryletherketone foamed board is a structural foam board used for structural core material.

8. The polyaryletherketone foamed plate according to claim 1, characterized in that: The thickness of the polyaryletherketone sheet is 3-10 mm; The supercritical fluid includes supercritical N2 and / or supercritical CO2; The pressure of the supercritical fluid is 7-20 MPa.

9. The polyaryletherketone foamed plate according to claim 1, characterized in that: The immersion time of the pressure-maintaining penetration is 120 to 180 minutes; The pressure of the pressure-maintaining penetration is 10-20 MPa.

10. The polyaryletherketone foamed plate according to claim 1, characterized in that: The immersion time for the second pressure-maintaining infiltration is 30 to 90 minutes; The pressure of the second pressure-maintaining penetration is 7-10 MPa; The pressure after the pressure relief is normal pressure; The pressure relief rate is 10~100MPa / s.

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