Foamable polymer foam particles having customized shape

Abstract

Disclosed in the present application are foamable polymer foam particles having a customized shape. The foam particles comprise one or two or more of a spherical shape, a cube-like shape and an irregular shape. Specifically, the present application further relates to a preparation method for the foam particles. The method comprises: subjecting raw materials to a first-stage prepolymerization, so as to obtain a prepolymer material; when the viscosity of the prepolymer material reaches 20-200 Pa·s, extruding the prepolymer material for shaping preparation, so as to obtain prepolymerized particles having a specific shape and size; subjecting the prepolymerized particles to a second-stage prepolymerization; and continuing to perform a high-temperature pre-foaming treatment on the particles, which have been subjected to the second-stage prepolymerization, so as to obtain foamable polymer foam particles having a customized shape. By subjecting the foam particles having the specific shape and size to in-mold foaming, a material product having excellent mechanical properties with high surface smoothness and low internal defect degree can be obtained.

Description

Custom shaped foamable polymer foam particles TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, and in particular to custom shaped foamable polymer foam particles and a method for preparing a special-shaped foam product by in-mold foaming. BACKGROUND

[0002] In today's industrial production, composite materials are increasingly used, such as composite materials made by combining polymeric foam materials with metals, carbon materials, etc. Foam materials themselves have good mechanical properties and can reduce the overall weight of the composite material. In production, to achieve good design effects, the foam materials used are often special-shaped parts with complex external structures and also need to have good mechanical properties. In the current technology, for foam materials with such special-shaped structures, the original material is generally produced in the form of a whole block, and then further processing is performed, such as CNC machining engraving, to obtain the required specific shape. However, this processing method has low utilization rate of raw materials, low efficiency, and high manufacturing cost, which limits large-scale production.

[0003] There are also methods for manufacturing special-shaped foam components by foaming polymer particles in a mold through an in-mold foaming process in the prior art. This process can directly form a finished foam part without the need for additional processing and molding, reducing waste of materials. However, the in-mold foaming products currently available on the market have problems such as poor surface smoothness and many internal defects, and their overall performance is poorer than that of foam boards processed by traditional processes. SUMMARY

[0004] The purpose of the present application is to provide a process for preparing in-mold foaming special-shaped parts with better performance, by in-mold foaming of custom shaped foamable particles in a special-shaped mold, to obtain special-shaped products with high surface smoothness and low internal defect rate in a more efficient manner.

[0005] Specifically, the present application provides a method for preparing custom shaped foamable polymer foam particles, comprising the following steps:

[0006] prepolymerizing raw materials in a first stage to obtain a prepolymer material,

[0007] extruding and shaping the prepolymer material when its viscosity reaches 20-200 Pa·s to obtain prepolymer particles with specific shapes and sizes,

[0008] prepolymerizing the prepolymer particles in a second stage,

[0009] continuing to perform high-temperature pre-foaming treatment on the particles after the second stage of prepolymerization to obtain the custom shaped foamable polymer foam particles.

[0010] Further, the shaping step comprises extruding the prepolymer and passing the extruded prepolymer through a compression roller having a groove with a specific shape.

[0011] Further, the first stage prepolymerization is performed at a temperature of 30-60°C for 10-20 hours.

[0012] Further, the second stage prepolymerization is performed at a temperature of 40-80°C for 10-20 hours.

[0013] Further, the custom-shaped foamable polymer foam particles comprise one or more of spherical, cubic-like, and irregular shapes.

[0014] Further, the raw materials comprise one or more of monomers, initiators, crosslinking agents, blowing agents, and other additives, wherein the monomers comprise one or more of acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, methyl methacrylate, amide compounds, acid anhydride compounds, or styrene; and the other additives comprise one or more of flame retardants, retarders, nucleating agents, dispersants, release agents, heat-resistant agents, and antioxidants.

[0015] Further, the raw materials comprise the following components in the following amounts: 80-150 parts of monomers, 0.04-10 parts of initiators, 0.02-5 parts of crosslinking agents, 0.5-25 parts of blowing agents, and 0.9-20 parts of other additives.

[0016] Further, the high-temperature pre-foaming is performed at a temperature of 170-220°C for 15-90 minutes.

[0017] Further, the prepolymer particles have a particle size of 0.3-3 mm, and the custom-shaped foamable polymer foam particles have a particle size of 1-9 mm.

[0018] The application further provides a custom-shaped foamable polymer foam particle prepared by the method for preparing custom-shaped foamable polymer foam particles.

[0019] Further, the custom-shaped foamable polymer foam particles comprise one or more of spherical, cubic-like, and irregular shapes.

[0020] Further, the custom-shaped foamable polymer foam particles have a particle size of 1-9 mm.

[0021] The application further provides a method for preparing an in-mold foamed special-shaped part, comprising the following steps: filling custom-shaped foamable polymer foam particles into a special-shaped part mold, performing in-mold foaming and curing to obtain the in-mold foamed special-shaped part.

[0022] Further, the customized shape of the foamable polymer foam particles is provided by the present application.

[0023] Further, the in-mold foaming curing comprises the following steps:

[0024] The mold filled with the foamable polymer foam particles is preheated at room temperature to 160℃ for 0.5 to 2 hours, and then heated at 200 to 250℃ for 0.5 to 12 hours, so that the particles in the mold are expanded and foamed to fill the mold cavity and completely cured.

[0025] The present application further provides a special-shaped foam material prepared by the preparation method of the in-mold foaming special-shaped part provided by the present application.

[0026] Effects of the application

[0027] The foaming material processing technology provided by the technical scheme of the present application can customize specific polymer particle shape and size according to the shape of the special-shaped part, and different sizes and shapes of particles are densely arranged in the mold cavity, foamed and formed into a special-shaped foam part. Compared with the existing in-mold foaming scheme, a product with excellent mechanical properties, high surface smoothness and low internal defect degree can be obtained. At the same time, compared with the processing method of cutting after the whole foam board is formed, the method of the present application can greatly reduce the material cost and improve the processing effect. BRIEF DESCRIPTION OF DRAWINGS

[0028] Fig. 1 is a diagram of a special-shaped part mold used in the embodiments of the present application. DETAILED DESCRIPTION

[0029] The present application will be further described in detail below with specific embodiments. The embodiments are given to enable a more thorough understanding of the present application and to enable the complete disclosure of the present application to be conveyed to those skilled in the art.

[0030] It should be noted that some terms are used in the specification and claims to refer to particular components. Those skilled in the art will understand that the same component can be referred to by different terms. The specification and claims do not distinguish components based on the difference in terminology, but rather on the difference in function. As used throughout the specification and claims, "comprising" or "including" is an open term, which should be interpreted to mean "including but not limited to". The subsequent description describes preferred embodiments of the present application, but the description is for the purpose of illustrating the general principles of the specification, and is not intended to limit the scope of the present application. The scope of protection of the present application is defined by the appended claims.

[0031] One aspect of the present application relates to a method for preparing a customized shape foamable polymer foam particle, comprising the following steps:

[0032] carrying out first stage prepolymerization on the raw material to obtain a prepolymer material,

[0033] carrying out shaping preparation on the prepolymer material by extrusion when the viscosity of the prepolymer material reaches 20-200 Pa·s to obtain a prepolymer particle with a specific shape and size,

[0034] carrying out second stage prepolymerization on the prepolymer particle,

[0035] continuing high-temperature pre-foaming treatment on the particle after the second stage prepolymerization to obtain the customized shape foamable polymer foam particle.

[0036] The customized shape in the present application refers to a specific shape set according to processing requirements. In some specific embodiments, the customized shape can be spherical or cubic.

[0037] In other specific embodiments, it can be any irregular shape set arbitrarily. In specific embodiments, the customized shape has a set size.

[0038] In some specific embodiments, the particle size of the prepolymer particle is 0.3-3 mm, and the particle size of the customized shape foamable polymer foam particle is 1-9 mm.

[0039] In the present application, the particle size of a spherical particle refers to the diameter of the sphere, the particle size of an expanded cubic particle refers to the distance between the highest point of the arc surface and the lowest point of the opposite surface, and the particle size of an irregular particle refers to the diameter of the screen mesh when the particle size is subdivided using a screen mesh.

[0040] In the present application, the particle size of the prepolymer particle refers to the average particle size of the obtained particle population of each shape.

[0041] In specific embodiments, the raw material comprises a monomer, an initiator, a crosslinking agent, a foaming agent, and other additives.

[0042] In specific embodiments, the monomer comprises one or two or more of acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, methyl methacrylate, an amide compound, an acid anhydride compound, or styrene.

[0043] In one specific embodiment, the monomer in the raw material is acrylic acid / methacrylic acid, and acrylonitrile / methacrylonitrile.

[0044] In some embodiments, the other auxiliary agent includes one or more than one of a flame retardant, a retarder, a nucleating agent, a dispersing agent, a release agent, a heat-resistant agent, and an antioxidant.

[0045] In some embodiments, the initiator is selected from one or more than one of t-amyl peroxyacetate, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-amyl peroxybenzoate, t-butyl peroxybenzoate, azobis isobutyronitrile, and azo isobutyronitrile carboxamide; and the foaming agent is selected from one or more than one of ethanol, propanol, isopropanol, water, t-butyl alcohol, and amyl alcohol.

[0046] In some embodiments, the other auxiliary agent includes one or more than one of a flame retardant, a retarder, a nucleating agent, a dispersing agent, a release agent, a heat-resistant agent, and an antioxidant.

[0047] In some embodiments, the mass fraction of each component in the raw material is: monomer 80-150 parts, initiator 0.04 to 10 parts, crosslinking agent 0.02 to 5 parts, foaming agent 0.5 to 25 parts, and other auxiliary agent 0.9 to 20 parts.

[0048] In some embodiments of the present application, the raw materials are mixed and first-stage pre-polymerization is performed to obtain a pre-polymer material. The reaction temperature of the first-stage pre-polymerization is 30-60°C, for example, 30, 35, 40, 35, 50, 55, 60°C, and the reaction time is 10-20 hours, for example, 10, 12, 14, 15, 16, 18, 20 hours.

[0049] In some embodiments, after the first-stage pre-polymerization, the pre-polymer material is extruded when the viscosity reaches 20-200 Pa·s, and is further shaped into a specific shape.

[0050] In the method provided by the present application, the raw materials are in an intermediate stage of changing from pure liquid to gel and then to solid during pre-polymerization, and have a certain viscosity. In this state, the pre-polymer can be processed into a specific particle shape. The viscosity can be measured by methods or instruments known in the art.

[0051] In some embodiments, the pre-polymer material can be shaped by a press roller, cutting, or the like.

[0052] In some embodiments, the pre-polymer with a certain viscosity is extruded into a long and thin sheet-shaped pre-polymer. The pre-polymer can be processed by a press roller with a specific shape groove to obtain a pre-polymer particle with a specific shape and size. The pre-polymer particle is collected and then subjected to a second-stage pre-polymerization reaction.

[0053] In specific embodiments, the second stage prepolymerization is carried out at a temperature of 40-80 °C, such as 40, 35, 50, 55, 60, 65, 70, 75, 80 °C, for a time period of 10-20 hours, such as 10, 12, 14, 15, 16, 18, 20 hours.

[0054] In specific embodiments, after the second stage prepolymerization of the prepolymerized particles is completed, the particles are further subjected to a high temperature pre-foaming treatment to obtain the custom shaped foamable polymer foam particles.

[0055] In specific embodiments, the high temperature pre-foaming treatment is carried out at a temperature of 170-220 °C, such as 170, 180, 190, 200, 210, 220 °C, for a time period of 15-90 minutes, such as 15, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80, 90 minutes.

[0056] The method provided in the present application improves the conventional process of foamable polymer particles. In the prepolymerization process, a shaping preparation process is added. Under certain process conditions, the prepolymer is shaped into a specific shape and size of polymer intermediate (i.e. prepolymerized particles), and then the subsequent prepolymerization reaction is completed, followed by further pre-foaming to obtain the corresponding shape and size of foamable polymer foam particles.

[0057] In specific embodiments, the prepolymerized particles obtained by the method have a particle size of 0.3-3 mm, such as 0.3, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 1.9, 2.0, 2.2, 2.5, 2.8, 3.0 mm.

[0058] In specific embodiments, the custom shaped foamable polymer foam particles obtained have a particle size of 1-9 mm, such as 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 9 mm.

[0059] Another aspect of the present application relates to a custom shaped foamable polymer foam particle. Specifically, the particle is obtained by the method of preparing a custom shaped foamable polymer foam particle described above.

[0060] In specific embodiments, the custom shaped foamable polymer foam particle can be one or more than one of spherical, cubic-like, irregular, etc. Specifically, it can be obtained by adjusting the corresponding shaping preparation conditions in the method described above.

[0061] In specific embodiments, the custom shaped foamable polymer foam particle has a particle size of 1-9 mm.

[0062] In some embodiments, the foamable polymer foam particles of the present application are PMI (polymethacrylimide) foam particles. PMI is currently the strongest and stiffest heat-resistant foam plastic, with outstanding structural stability and mechanical properties.

[0063] In some embodiments, the foamable polymer foam particles of the present application are PMMA (polymethyl methacrylate) foam particles. In other embodiments, the foamable polymer foam particles are PEI (polyetherimide) foam particles. It will be appreciated by those skilled in the art that the preparation method of the present application can also be used to prepare other different types of foam material particles.

[0064] Another aspect of the present application relates to a method for preparing an in-mold foamed profile, comprising the steps of: filling the foamable polymer foam particles of customized shape into a profile mold, and performing in-mold foaming and curing to obtain the in-mold foamed profile.

[0065] In some embodiments, the foamable polymer foam particles of customized shape are prepared by the method for preparing foamable polymer foam particles of customized shape provided by the present application.

[0066] Further, in some embodiments, the foamable polymer foam particles of customized shape are the foamable polymer foam particles of customized shape provided by the present application.

[0067] In some embodiments, the foamable polymer foam particles comprise one or more than one of spherical shape, cubic-like shape, and irregular shape.

[0068] In some embodiments, the proportion of the foamable polymer foam particles of customized shape in all the particles filled into the profile mold in the preparation method is more than 90% (volume ratio), preferably more than 95%, and more preferably more than 98%.

[0069] In some embodiments, the foamable polymer foam particles of customized shape can be selected according to the shape structure and surface roughness requirements of different profiles.

[0070] In some embodiments, the in-mold foaming and curing comprises the steps of:

[0071] The mold filled with the foamable polymer foam particles is preheated at room temperature to 160°C for 0.5 to 2 hours, and then heated at 200 to 250°C for 0.5 to 12 hours, so that the particles in the mold expand and foam to fill the mold cavity and completely cure.

[0072] The application also provides a profiled foam material prepared by the preparation method.

[0073] Embodiment

[0074] The application generally and / or specifically describes the materials used in the experiment and the experimental methods. In the following examples, % means wt%, i.e., weight percentage, if no other specific description is given. If no specific description is given, the reagents and instruments used are conventional reagent products or conventional experimental instruments that can be commercially available.

[0075] Preparation of an in-mold foaming profiled part in Example 1

[0076] (1) The raw materials were subjected to first-stage pre-polymerization at a temperature of 55°C for 15 hours to obtain a pre-polymer. The raw material composition (mass fraction) was as follows: 80 parts of methacrylic acid, 50 parts of methacrylonitrile, 0.5 parts of initiator azobisisobutyronitrile, 2 parts of crosslinking agent acrylamide, 8 parts of foaming agent isopropyl alcohol, and 3 parts of nucleating agent nano-silicon dioxide.

[0077] (2) The pre-polymer with a viscosity value of 110 Pa·s was extruded into a long strip sheet, and after shaping processing by a compression roller with a spherical processing groove, spherical pre-polymer particles with an average particle size of 1.8 mm were obtained.

[0078] (3) The spherical pre-polymer particles obtained in the above step were further subjected to second-stage pre-polymerization in an oven at a temperature of 40-80°C for 15 hours.

[0079] (4) Subsequently, the particles were treated at a high temperature of 195°C for 1 hour to obtain foamable polymer foam particles with a particle size of 5 mm.

[0080] (5) The foamable polymer foam particles obtained in the above step were filled into a profiled mold as shown in FIG. 1, preheated at room temperature to 160°C for 1 hour, and then foamed and solidified at 230°C for 6 hours. The particles expanded and foamed, filled the mold cavity, and completely solidified.

[0081] (6) After the foaming was completed, the mold was cooled and the foamed inner core was taken out.

[0082] Preparation of an in-mold foaming profiled part in Example 2

[0083] (1) The raw materials were subjected to first-stage pre-polymerization at a temperature of 55°C for 15 hours to obtain a pre-polymer. The raw material composition (mass fraction) was as follows: 80 parts of methacrylic acid, 50 parts of methacrylonitrile, 0.5 parts of initiator azobisisobutyronitrile, 2 parts of crosslinking agent acrylamide, 8 parts of foaming agent isopropyl alcohol, and 3 parts of nucleating agent nano-silicon dioxide.

[0084] (2) The above prepolymer with viscosity value of 110 Pa-s was extruded into long thin plate, and after being shaped and processed by compression roller with cubic processing groove, cubic prepolymer PMI particles with average particle size of 1.8 mm were obtained.

[0085] (3) The cubic prepolymer particles obtained in the above step were continuously subjected to second stage prepolymerization in an oven at 40-80 °C for 15 hours.

[0086] (4) Then, after being treated at high temperature of 195 °C for 1 hour, foamable polymer foam particles with particle size of 5 mm were obtained.

[0087] (5) The foamable polymer foam particles obtained in the above step were filled into the special-shaped mold shown in FIG. 1, preheated at room temperature to 160 °C for 1 hour, foamed and solidified at 200 °C for 6 hours, and the particles were expanded and foamed to fill the mold cavity and completely solidified.

[0088] (6) After the foaming was completed, the mold was cooled and the foamed inner core was taken out.

[0089] Preparation of special-shaped in-mold foaming part

[0090] (1) The raw materials were subjected to first stage prepolymerization at a temperature of 55 °C for 15 hours to obtain a prepolymer. The raw material composition (mass fraction) was: 80 parts of methacrylic acid, 50 parts of methacrylonitrile, 0.5 parts of initiator azobisisobutyronitrile, 2 parts of crosslinking agent acrylamide, 8 parts of foaming agent isopropyl alcohol, and 3 parts of nucleating agent nano-silicon dioxide.

[0091] (2) The above prepolymer with viscosity value of 110 Pa-s was extruded into long thin plate, and after being shaped and processed by compression roller with cubic processing groove, cubic prepolymer PMI particles with average particle size of 1.8 mm were obtained.

[0092] (3) The cubic prepolymer particles obtained in the above step were continuously subjected to second stage prepolymerization in an oven at 40-80 °C for 15 hours.

[0093] (4) Then, after being treated at high temperature of 195 °C for 1 hour, foamable polymer foam particles with particle size of 5 mm were obtained.

[0094] (5) The foamable polymer foam particles obtained in the above step were filled into the special-shaped mold shown in FIG. 1, preheated at room temperature to 160 °C for 1 hour, foamed and solidified at 200 °C for 6 hours, and the particles were expanded and foamed to fill the mold cavity and completely solidified.

[0095] (6) After the foaming was completed, the mold was cooled and the foamed inner core was taken out.

[0096] Preparation of special-shaped in-mold foaming part

[0097] (1) The raw materials were pre-polymerized at 55°C for 15 hours to obtain a pre-polymer. The raw material composition (mass fraction) was: methacrylic acid 80 parts, methacrylonitrile 50 parts, initiator azobisisobutyronitrile 0.5 parts, crosslinking agent acrylamide 2 parts, foaming agent isopropyl alcohol 8 parts, nucleating agent nano-silica 3 parts.

[0098] (2) The pre-polymer with a viscosity value of 110 Pa·s was extruded into a long strip sheet, and after shaping processing by a compression roller with a spherical processing groove, spherical pre-polymer particles with an average particle size of 0.5 mm were obtained.

[0099] (3) The spherical pre-polymer particles obtained in the previous step were further pre-polymerized in an oven at 40-80°C for 15 hours.

[0100] (4) Then treated at high temperature 195°C for 1 hour, obtainable foam polymer foam particles with a particle size of 1.3 mm.

[0101] (5) The obtainable foam polymer foam particles obtained in the previous step were filled into a special-shaped mold as shown in Figure 1, preheated at room temperature to 160°C for 1 hour, then foamed and solidified at 200°C for 6 hours, the particles expanded and foamed, filled the mold cavity, and completely solidified.

[0102] (6) After the foaming was completed, the mold was cooled and the foamed inner core was taken out.

[0103] Preparation of a special-shaped in-mold foaming part

[0104] (1) The raw materials were pre-polymerized at 55°C for 15 hours, then heated to 70°C for pre-polymerization for 15 hours to obtain a PMI pre-polymer. The raw material composition (mass fraction) was: methacrylic acid 80 parts, methacrylonitrile 50 parts, initiator azobisisobutyronitrile 0.5 parts, crosslinking agent acrylamide 2 parts, foaming agent isopropyl alcohol 8 parts, nucleating agent nano-silica 3 parts.

[0105] (2) The PMI pre-polymer obtained in the previous step was broken into irregularly shaped particles by a crusher, and the particle size was sieved using a screen to obtain irregular particles with a particle size of 1.8 mm.

[0106] (3) Then treated at high temperature 195°C for 1 hour, obtainable PMI foam particles with a particle size of 4.5-5 mm.

[0107] (4) The obtainable PMI foam particles obtained in the previous step were filled into a special-shaped mold as shown in Figure 1, preheated at room temperature to 160°C for 1 hour, then foamed and solidified at 200°C for 6 hours, the particles expanded and foamed, filled the mold cavity, and completely solidified.

[0108] (5) After the foaming was completed, the mold was cooled and the foamed inner core was taken out.

[0109] Comparative Example 2

[0110] (1) The raw materials were subjected to first-stage prepolymerization at a temperature of 55°C for 15 hours to obtain a prepolymer. The raw material composition (mass fraction) was as follows: 80 parts of methacrylic acid, 50 parts of methacrylonitrile, 0.5 parts of initiator azobisisobutyronitrile, 2 parts of crosslinking agent acrylamide, 8 parts of foaming agent isopropyl alcohol, and 3 parts of nucleating agent nano-silica.

[0111] (2) The prepolymer with a viscosity value of 10 Pa·s was subjected to extrusion, but the material viscosity was too low to be pressed into a long strip sheet. After shaping processing by a compression roller with a spherical processing groove, it was still in a sheet structure;

[0112] (3) The sheet-shaped prepolymer particles obtained in the above step were subjected to second-stage prepolymerization in an oven at 40-80°C for 15 hours.

[0113] (4) The PMI prepolymer obtained in the above step was crushed into irregularly shaped particles by a crusher, and the particle size was sieved using a screen to obtain irregular particles with a particle size of 1.8 mm.

[0114] (5) Subsequently, the foamable polymer foam particles with a particle size of 5 mm were obtained by treating at a high temperature of 195°C for 1 hour.

[0115] (6) The foamable polymer foam particles obtained in the above step were filled into a special-shaped mold as shown in FIG. 1, preheated at room temperature to 160°C for 1 hour, foamed and solidified at 230°C for 6 hours, and the particles were expanded and foamed to fill the mold cavity and completely solidified.

[0116] (7) After the foaming was completed, the mold was cooled and the foamed core was taken out.

[0117] Experimental Example 1: Mechanical property determination of special-shaped foam material

[0118] The special-shaped samples obtained in the above examples and comparative examples were subjected to mechanical property determination, and the results are shown in Table 1.

[0119] Among them, the apparent density was determined according to “GB / T 6343-2009 Determination of apparent density of foamed plastics and rubbers”; the tensile strength was determined according to “ASTM-D638-2010 Tensile testing of plastics”; the compression strength was determined according to “GB / T 8813-2008 Determination of compression properties of rigid foamed plastics”; and the shear strength was determined according to “ASTM C638 Shear properties of sandwich core materials”.

[0120] From the above experimental results, it can be seen that, by using the method of the present application, the in-mold foaming special-shaped part prepared by in-mold foaming of the foamed polymer foam particles with a specific shape can obtain a special-shaped part with more excellent mechanical properties compared with the conventional in-mold foaming method in the prior art. And through observation, it can be found that the surface roughness of the samples of Examples 1-4 is lower, and they have both performance and aesthetics. In the case of the same performance, the product with lower density can be selected, which also provides more support for lightweight.

[0121] The above merely describes preferred embodiments of the present application, but does not represent other forms of limitation to the present application. Any person skilled in the art can modify or alter the above disclosed technical content into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and alteration made to the above embodiments without departing from the technical content of the present application, and according to the technical essence of the present application, still falls within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing custom-shaped expandable polymer foam particles, comprising the following steps: The raw materials undergo a first-stage prepolymerization to obtain a prepolymer material. When the viscosity of the prepolymer material reaches 20-200 Pa·s, it is extruded and shaped to obtain prepolymer particles of specific shapes and sizes. The prepolymerized particles are subjected to a second stage of prepolymerization. The particles after the second stage of prepolymerization are further subjected to high-temperature pre-foaming treatment to obtain foamable polymer foam particles of the customized shape.

2. The method according to claim 1, wherein, The shaping and preparation steps include extruding the prepolymer material and then processing it through pressure rollers with grooves of a specific shape.

3. The method according to claim 1, wherein, The temperature of the first stage of prepolymerization is 30-60℃, and the reaction time is 10-20 hours.

4. The method according to claim 1, wherein, The second stage of prepolymerization is carried out at a temperature of 40–80°C for 10–20 hours.

5. The method according to claim 1, wherein, The custom-shaped expandable polymer foam particles include one or more of the following shapes: spherical, cubic, and irregular.

6. The method according to claim 1, wherein, The raw materials include monomers, initiators, crosslinking agents, foaming agents, and other additives. The monomers include one or more of acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, methyl methacrylate, amide compounds, acid anhydride compounds, or styrene. The other additives include one or more of flame retardants, retarders, nucleating agents, dispersants, release agents, heat resistant agents, and antioxidants.

7. The method according to claim 6, wherein, The mass fractions of each component in the raw material are as follows: 80-150 parts monomer, 0.04 to 10 parts initiator, 0.02 to 5 parts crosslinking agent, 0.5 to 25 parts foaming agent, and 0.9 to 20 parts other additives.

8. The method according to claim 1, wherein, The high-temperature pre-foaming temperature is 170-220℃, and the reaction time is 15-90 minutes.

9. The preparation method according to claim 1, wherein, The prepolymer particles have a particle size of 0.3-3 mm, and the custom-shaped expandable polymer foam particles have a particle size of 1-9 mm.

10. A custom-shaped expandable polymer foam particle, which is prepared by the method of any one of claims 1 to 9.

11. The expandable polymer foam particles according to claim 10, wherein, The particles include one or more of the following shapes: spherical, cubical, and irregular.

12. The expandable polymer foam particles according to claim 10, wherein, The particle size is 1-9 mm.

13. A method for preparing an in-mold foamed irregular-shaped part, comprising the following steps: Custom-shaped expandable polymer foam particles are filled into a mold for irregularly shaped parts, and in-mold foaming and curing are performed to obtain the in-mold foamed irregularly shaped parts. The custom-shaped expandable polymer foam particles are those described in any one of claims 10 to 12.

14. The preparation method according to claim 13, wherein, The in-mold foaming and curing process includes the following steps: Preheat the mold filled with expandable polymer foam particles at room temperature to 160°C for 0.5 to 2 hours, and then heat it at 200 to 250°C for 0.5 to 12 hours to allow the particles in the mold to expand and foam to fill the mold cavity and completely solidify.

15. An irregularly shaped foam material, which is prepared by the preparation method according to claim 13 or 14.

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