Gel network supported chemical foaming agent, and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of macromolecular polyethylene foaming materials. Disclosed are a gel network supported chemical foaming agent, and a preparation method therefor and the use thereof. The gel network supported chemical foaming agent comprises a gel network carrier and azodicarbonamide supported on the gel network carrier, wherein on the basis of the total weight of the gel network supported chemical foaming agent, the content of the azodicarbonamide is 10-40 wt%, and the content of the gel network carrier is 60-90 wt%. The gel network supported chemical foaming agent has a relatively low initial foaming temperature, a controllable decomposition process, a relatively small cell size and superior application value.

Description

Gel network supported chemical foaming agents, their preparation methods and applications

[0001] Cross-references to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411683452.4, filed on November 22, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of polymer polyethylene foaming materials technology, specifically to a gel network supported chemical foaming agent, its preparation method, and its application. Background Technology

[0004] Traditional chemical blowing agents used in the manufacture of polyolefin foam materials are limited by their simple structure, violent decomposition reactions, and difficulty in controlling pore size, which seriously hinders further optimization of material properties and functional expansion. Therefore, the development of composite blowing agent materials, especially supported blowing agent systems that can be controlled through multi-component design and precise pore structure regulation, has become a focus of attention in academia and industry. These systems not only enable precise control of the foaming mechanism through sophisticated synthesis strategies but also indicate significant research value and application prospects, potentially opening a new chapter in the field of foam materials.

[0005] Supported catalyst systems have been widely applied and extensively studied in the chemical industry, particularly due to their significant advantages in providing abundant active sites, accelerating chemical reaction rates, and reducing activation energy. The design of supported blowing agents can draw upon their successful experiences. In such catalyst systems, the support material plays a crucial role, determining not only the catalyst's dispersion and utilization rate but also ensuring its structural stability and durability under extreme reaction conditions. Careful selection of the support also affects the catalyst's selectivity and lifetime, further highlighting its core role in constructing high-performance catalytic systems.

[0006] In recent years, gels, as a novel material with high specific surface area, excellent thermal insulation, and flame retardancy, have gradually attracted widespread attention from researchers. Although gels have broad application prospects in many fields, their application as a carrier in polyolefin foam materials, especially in controlling cell formation during the foaming process of complex large structures, remains a gap. Therefore, technological innovation surrounding supported foaming agents for rotational molding of polyethylene, particularly through precise control of the thermal decomposition behavior and kinetics of the foaming agent to optimize the foaming effect and material properties of polyethylene, has become a key research focus. The aim is to overcome existing technical challenges, promote advancements in foaming processes, and improve the quality of polyethylene foam materials. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of excessively high decomposition temperature and uncontrollable decomposition process of polyethylene foaming agents in the prior art, and to provide a gel network supported chemical foaming agent, its preparation method and application. This gel network supported chemical foaming agent has a lower initial foaming temperature, a controllable decomposition process, and smaller cell size, and has better application value.

[0008] To achieve the above objectives, a first aspect of the present invention provides a gel network-supported chemical foaming agent comprising a gel network carrier and azodicarbonamide supported on the gel network carrier, wherein, based on the total weight of the gel network-supported chemical foaming agent, the content of the azodicarbonamide is 10-40% by weight and the content of the gel network carrier is 60-90% by weight.

[0009] Preferably, the azodicarbonamide has a particle size of 12-18 μm.

[0010] Preferably, the gel network carrier is an aluminum-based gel network carrier and / or a silicon-based gel network carrier, and more preferably a silicon-based gel network carrier.

[0011] A second aspect of the present invention provides a method for preparing a gel network-supported chemical foaming agent, the method comprising the following steps:

[0012] (1) Mix the sol and stabilizer and perform a first stirring to obtain a mixture;

[0013] (2) The mixture and azodicarbonamide are mixed and subjected to ultrasonic treatment and second stirring in sequence to obtain a suspension;

[0014] (3) The suspension is freeze-dried.

[0015] The sol is an aluminum sol and / or a silica sol.

[0016] Preferably, the stabilizer is carboxymethyl cellulose.

[0017] Preferably, the mass ratio of the sol to the stabilizer is (80-130):1.

[0018] Preferably, the mass ratio of the silica sol to the stabilizer is (80-110):1.

[0019] Preferably, the mass ratio of the aluminum sol to the stabilizer is (110-130):1.

[0020] Preferably, the mass ratio of the sol to the azodicarbonamide is 1:(0.008-0.2).

[0021] Preferably, the conditions for the first stirring include: a stirring rate of 800-1400 r / m and a stirring time of 2-4 h.

[0022] Preferably, the conditions for the second stirring include: a stirring rate of 800-1400 r / m and a stirring time of 2-8 h.

[0023] Preferably, the freeze-drying conditions include a temperature of -55 to -85°C and a time of 24 to 72 hours.

[0024] A third aspect of the present invention provides a gel network-supported chemical foaming agent prepared by the method described above.

[0025] The fourth aspect of the present invention provides the application of the above-mentioned gel network-supported chemical foaming agent in polyethylene rotational molding.

[0026] The gel network-supported chemical foaming agent of this invention has a different foaming mechanism and technical effect than chemical foaming agents in the prior art, as detailed below:

[0027] (1) The gel network carrier has an organic structure that can completely encapsulate azodicarbonamide. This encapsulation not only improves the dispersibility of azodicarbonamide and makes the foaming effect more uniform and delicate, but also effectively prevents the aggregation of azodicarbonamide, thereby enhancing its stability.

[0028] (2) The spatial structure of the gel network carrier forms a thermal barrier effect, which can reduce the thermal impact of the decomposition reaction of azodicarbonamide and make the temperature fluctuation during the foaming process more stable. This stable temperature environment is conducive to the uniform decomposition of azodicarbonamide, thereby improving the foaming ratio and the stability of the foaming effect.

[0029] (3) The gel network-supported chemical foaming agent of the present invention effectively reduces the initial decomposition temperature of azodicarbonamide foaming agent and slows down its thermal decomposition rate. This regulatory effect makes the foaming process more controllable and facilitates the adjustment of foaming speed and foaming ratio according to actual needs. At the same time, reducing the initial decomposition temperature and slowing down the thermal decomposition rate helps to improve the performance of azodicarbonamide in rotational molding foaming. Attached Figure Description

[0030] Figure 1 is a thermogravimetric analysis diagram of the gel network supported chemical foaming agents prepared in Example 1 and Comparative Example 2;

[0031] Figure 2 is a comparison of the cell diameters of polyethylene foam materials prepared by gel network-supported chemical foaming agents in Example 1 and Comparative Example 2.

[0032] Figure 3 is a comparison of the pore volumes of polyethylene foam materials prepared by gel network-supported chemical foaming agents in Example 1 and Comparative Example 2. Detailed Implementation

[0033] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0034] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] The gel network-supported chemical foaming agent of this invention contains a gel network carrier and azodicarbonamide supported on the gel network carrier. Based on the total weight of the gel network-supported chemical foaming agent, the content of azodicarbonamide is 10-40% by weight, and the content of the gel network carrier is 60-90% by weight. According to the gel network-supported chemical foaming agent of this invention, the gel network carrier improves the dispersibility of azodicarbonamide, resulting in more uniform cell size and improved foaming effect. The gel network carrier reduces the thermal impact of the decomposition reaction, making temperature fluctuations during the foaming process more stable, which is beneficial for the uniform decomposition of azodicarbonamide, thereby improving the foaming ratio and the stability of the foaming effect. The gel network carrier lowers the decomposition temperature and slows down its thermal decomposition rate, making the foaming process more controllable. The resulting cells in the polyethylene rotational molding process are smaller in size, with a cell diameter of less than 200 μm, thus having better application value.

[0036] In the gel network supported chemical foaming agent of this invention, in order to obtain an azodicarbonamide supported structure and thus improve the foaming effect, the particle size of the azodicarbonamide is preferably 12-18 μm. This particle size range of the azodicarbonamide is beneficial for preparing a more uniform cell distribution and obtaining a better foaming effect.

[0037] In the gel network-supported chemical foaming agent of the present invention, the foaming effect and stability are improved by controlling the thermal decomposition process. The gel network carrier is preferably an aluminum-based gel network carrier and / or a silicon-based gel network carrier, and more preferably a silicon-based gel network carrier.

[0038] In some embodiments, the gel network-supported chemical foaming agent of the present invention contains a gel network carrier and azodicarbonamide supported on the gel network carrier, wherein, based on the total weight of the gel network-supported chemical foaming agent, the content of azodicarbonamide is 10-40% by weight, the content of the gel network carrier is 60-90% by weight, the particle size of the azodicarbonamide is 12-18 μm, and the gel network carrier is an aluminum-based gel network carrier and / or a silicon-based gel network carrier.

[0039] This invention also provides a method for preparing a gel network-supported chemical foaming agent, the method comprising the following steps:

[0040] (1) Mix the sol and stabilizer and perform a first stirring to obtain a mixture;

[0041] (2) The mixture and azodicarbonamide are mixed and subjected to ultrasonic treatment and second stirring in sequence to obtain a suspension;

[0042] (3) The suspension is freeze-dried.

[0043] The sol is an aluminum sol and / or a silica sol.

[0044] According to the method described in this invention, azodicarbonamide is loaded onto a gel network carrier by freeze-drying, which improves the dispersibility of azodicarbonamide, makes the cell structure more uniform, and enhances the foaming effect. Moreover, it lowers the initial decomposition temperature, making the initial foaming temperature in the polyethylene foaming process more suitable and controllable, which is conducive to preparing a more uniform cell distribution and obtaining a better foaming effect.

[0045] In the method described in this invention, to ensure the stability of the sol, the stabilizer is preferably carboxymethyl cellulose. The solid content of the silica sol can be 25-35%, preferably 28-32%. The solid content of the aluminum sol can be 4-6%, preferably 4.5-5.5%. The mass ratio of the sol to the stabilizer can be (80-130):1, preferably (100-125):1. The mass ratio of the silica sol to the stabilizer can be (80-110):1, preferably (95-105):1. The mass ratio of the aluminum sol to the stabilizer can be (110-130):1, preferably (120-130):1.

[0046] In the method described in this invention, in order to improve the foaming effect and stability, the mass ratio of the sol to the azodicarbonamide is preferably 1:(0.008-0.2), more preferably 1:(0.016-0.12), and specifically, it can be 1:0.008, 1:0.01, 1:0.016, 1:0.02, 1:0.024, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, 1:0.053, 1:0.06, 1:0.065, 1:0.07, 1:0.075, 1:0.08, 1:0.085, 1:0.09, 1:0.095, 1:0.1, 1:0.12, 1:0.15, or 1:0.2. The mass ratio of the silica sol to the azodicarbonamide can be 1:(0.03-0.2), preferably 1:(0.03-0.12. The mass ratio of the aluminum sol to the azodicarbonamide can be 1:(0.008-0.053), preferably 1:(0.016-0.024).

[0047] In the method described in this invention, the conditions for the first stirring include: the temperature can be 20-40℃, preferably 20-30℃; the stirring rate can be 800-1400r / m, preferably 1200-1400r / m; and the time can be 2-4h, preferably 3-4h.

[0048] In the method described in this invention, in order to obtain an azodicarbonamide-supported structure and thereby improve the foaming effect, the ultrasonic treatment time is preferably 25-40 min, more preferably 30-40 min.

[0049] In the method described in this invention, the conditions for the second stirring include: the temperature can be 20-40℃, preferably 20-30℃; the stirring rate can be 800-1400r / m, preferably 1200-1400r / m; and the time can be 2-8h, preferably 6-8h.

[0050] In the method described in this invention, the freeze-drying conditions include: a temperature of -55 to -85°C, preferably -75 to -85°C; and a time of 24 to 72 hours, preferably 48 to 72 hours.

[0051] In some embodiments, the preparation method of the gel network-supported chemical foaming agent of the present invention includes the following steps:

[0052] (1) Mix the sol and stabilizer and stir for 2-4 hours at 20-40℃ with a stirring rate of 800-1400r / m to obtain a mixture;

[0053] (2) The mixture and azodicarbonamide are mixed and subjected to ultrasonic treatment for 25-40 min and then stirred for 2-8 h at 20-40℃ with a stirring rate of 800-1400 r / m to obtain a suspension.

[0054] (3) The suspension is freeze-dried at -55 to -85°C for 24-72 hours.

[0055] Wherein, the sol is an aluminum sol and / or a silica sol; the solid content of the silica sol is 25-35%; the solid content of the aluminum sol is 4-6%; the mass ratio of the amount of sol to the amount of stabilizer is (80-130):1; the mass ratio of the amount of sol to the amount of azodicarbonamide is 1:(0.008-0.2).

[0056] In other embodiments, the preparation method of the gel network-supported chemical foaming agent of the present invention includes the following steps:

[0057] (1) Mix the sol and stabilizer and stir for 3-4 hours at 20-30℃ with a stirring rate of 1200-1400r / m to obtain a mixture;

[0058] (2) The mixture and azodicarbonamide are mixed and subjected to ultrasonic treatment for 30-40 min and then stirred for 6-8 h at 20-30℃ with a stirring rate of 1200-1400 r / m to obtain a suspension.

[0059] (3) The suspension was freeze-dried at -75 to -85°C for 48-72 hours.

[0060] Wherein, the sol is an aluminum sol and / or a silica sol; the solid content of the silica sol is 28-32%; the solid content of the aluminum sol is 4.5-5.5%; the mass ratio of the sol to the stabilizer is (100-125):1; the mass ratio of the sol to the azodicarbonamide is 1:(0.016-0.12).

[0061] The present invention also provides a gel network supported chemical foaming agent prepared by the above method. The gel network supported chemical foaming agent according to the present invention improves the dispersibility of azodicarbonamide, effectively prevents the aggregation of azodicarbonamide particles, thereby enhancing its stability; effectively reduces the initial decomposition temperature of azodicarbonamide and slows down its thermal decomposition rate; and forms a thermal barrier effect, reducing the thermal impact of the azodicarbonamide decomposition reaction.

[0062] This invention also provides the application of the aforementioned gel network-supported chemical foaming agent in polyethylene rotational molding. According to the application described in this invention, in polyethylene rotational molding, the initial decomposition temperature of the gel network-supported chemical foaming agent is approximately 160°C, which is a more suitable temperature. At this temperature, the polyethylene melt viscosity is high, exhibiting both good fluidity and a certain viscosity, resulting in smaller and more uniform bubbles, thus improving the foaming effect. When the temperature is too high, the polyethylene viscosity is low, resulting in larger bubbles and a higher likelihood of bubble coalescence. Furthermore, the gel network-supported chemical foaming agent of this invention produces a more uniform and delicate foaming effect, improving the foaming ratio and the stability of the foaming effect. The foaming process is more controllable, facilitating adjustments to the foaming speed and foaming ratio according to actual needs.

[0063] The following examples further illustrate the gel network-supported chemical foaming agent, its preparation method, and its application according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0064] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, all experimental materials used in the following examples are commercially available. The azodicarbonamide used in the examples was purchased from Adamas Reagents Ltd., with a particle size of 12-18 μm; the silica sol used in the examples was purchased from Guangdong Huierte Nanotechnology Co., Ltd., with a solid content of 30%; the alumina sol used in the examples was purchased from Zibo Jinqi Chemical Technology Co., Ltd., brand name LA-10, with a solid content of 8%. The carboxymethyl cellulose used in the examples was purchased from Beijing Innocare Technology Co., Ltd., and was of analytical grade.

[0065] Example 1

[0066] (1) Mix 40g of silica sol and 0.4g of carboxymethyl cellulose and stir for 4 hours at 25°C with a stirring rate of 1000r / m to obtain a mixture;

[0067] (2) The mixture obtained in step (1) was mixed with 4.8 g of azodicarbonamide and subjected to ultrasonic treatment for 30 min and then stirred for 8 h at 25 °C with a stirring rate of 1000 r / m to obtain a suspension.

[0068] (3) The suspension obtained in step (2) is freeze-dried at -60°C for 24 hours to obtain a gel network supported chemical foaming agent.

[0069] Example 2

[0070] (1) Mix 80g of silica sol and 0.8g of carboxymethyl cellulose and stir for 4 hours at 25°C with a stirring rate of 1000r / m to obtain a mixture;

[0071] (2) The mixture obtained in step (1) was mixed with 3.6 g of azodicarbonamide and subjected to ultrasonic treatment for 30 min and then stirred for 8 h at 25 °C with a stirring rate of 1000 r / m to obtain a suspension.

[0072] (3) The suspension obtained in step (2) is freeze-dried at -60°C for 48 hours to obtain a gel network supported chemical foaming agent.

[0073] Example 3

[0074] (1) Mix 100g of silica sol and 1.2g of carboxymethyl cellulose and stir for 4 hours at 35°C with a stirring rate of 1400r / m to obtain a mixture;

[0075] (2) The mixture obtained in step (1) was mixed with 3.6 g of azodicarbonamide and subjected to ultrasonic treatment for 30 min and then stirred for 8 h at 35 °C with a stirring rate of 1400 r / m to obtain a suspension.

[0076] (3) The suspension obtained in step (2) is freeze-dried at -80°C for 72 hours to obtain a gel network supported chemical foaming agent.

[0077] Example 4

[0078] (1) Mix 75g aluminum sol and 0.6g carboxymethyl cellulose and stir for 4 hours at 35℃ with a stirring rate of 1400r / m to obtain a mixture;

[0079] (2) The mixture obtained in step (1) was mixed with 1.2 g of azodicarbonamide and subjected to ultrasonic treatment for 30 min and then stirred for 8 h at 35 °C with a stirring rate of 1400 r / m to obtain a suspension.

[0080] (3) The suspension obtained in step (2) is freeze-dried at -80°C for 72 hours to obtain a gel network supported chemical foaming agent.

[0081] Example 5

[0082] (1) Mix 150g aluminum sol and 1.2g carboxymethyl cellulose and stir for 4 hours at 35℃ with a stirring rate of 1400r / m to obtain a mixture;

[0083] (2) The mixture obtained in step (1) was mixed with 3.6 g of azodicarbonamide and subjected to ultrasonic treatment for 30 min and then stirred for 8 h at 35 °C with a stirring rate of 1400 r / m to obtain a suspension.

[0084] (3) The suspension obtained in step (2) is freeze-dried at -80°C for 72 hours to obtain a gel network supported chemical foaming agent.

[0085] Example 6

[0086] (1) Mix 64g of silica sol and 0.8g of carboxymethyl cellulose and stir for 4 hours at 20°C with a stirring rate of 800r / m to obtain a mixture;

[0087] (2) The mixture obtained in step (1) was mixed with 12.8 g of azodicarbonamide and subjected to ultrasonic treatment for 40 min and then stirred for 6 h at 20 °C with a stirring rate of 800 r / m to obtain a suspension.

[0088] (3) The suspension obtained in step (2) is freeze-dried at -55°C for 72 hours to obtain a gel network-supported chemical foaming agent.

[0089] Example 7

[0090] (1) Mix 64g of aluminum sol and 0.8g of carboxymethyl cellulose and stir for 2 hours at 40°C with a stirring rate of 1400r / m to obtain a mixture;

[0091] (2) The mixture obtained in step (1) was mixed with 0.6 g of azodicarbonamide and subjected to ultrasonic treatment for 25 min and then stirred for 2 h at 40 °C with a stirring rate of 1400 r / m to obtain a suspension.

[0092] (3) The suspension obtained in step (2) is freeze-dried at -85°C for 72 hours to obtain a gel network-supported chemical foaming agent.

[0093] Comparative Example 1

[0094] (1) Mix 48g of silica sol and 0.048g of carboxymethyl cellulose and stir for 4 hours at 25°C with a stirring rate of 1000r / m to obtain a mixture;

[0095] (2) The mixture obtained in step (1) is mixed with 40g of azodicarbonamide and subjected to ultrasonic treatment for 30min and then stirred for 8h at 25℃ with a stirring rate of 1000r / m to obtain a suspension.

[0096] (3) The suspension obtained in step (2) is freeze-dried at -60°C for 24 hours to obtain a gel network supported chemical foaming agent.

[0097] Comparative Example 2

[0098] The purchased azodicarbonamide was used directly as a chemical foaming agent.

[0099] Comparative Example 3

[0100] (1) Mix 40g of silica sol and 0.4g of carboxymethyl cellulose and stir for 4 hours at 25°C with a stirring rate of 1000r / m to obtain a mixture;

[0101] (2) The mixture obtained in step (1) was mixed with 0.6 g of azodicarbonamide and subjected to ultrasonic treatment for 30 min and then stirred for 8 h at 25 °C with a stirring rate of 1000 r / m to obtain a suspension.

[0102] (3) The suspension obtained in step (2) is freeze-dried at -60°C for 24 hours to obtain a gel network supported chemical foaming agent.

[0103] Comparative Example 4

[0104] The gel network-supported chemical foaming agent was prepared according to the method of Example 1, except that in step (3), the suspension obtained in step (2) was dried at 50°C for 72 hours to obtain the gel network-supported chemical foaming agent.

[0105] Test Example 1

[0106] The gel network supported chemical foaming agents prepared in Examples 1-7 and Comparative Examples 1-4 were subjected to thermogravimetric analysis (TGA) using a thermogravimetric analyzer. The TGA method was performed in accordance with the national standard GB / T17050-1997 "Terminology for Thermal Radiation". The TGA chromatograms of the gel network supported chemical foaming agents prepared in Example 1 and Comparative Example 2 are shown in Figure 1. The initial decomposition temperatures of the gel network supported chemical foaming agents prepared in Examples 1-7 and Comparative Examples 1-4 are recorded in Table 1. The mass percentages of azodicarbonamide and gel network carrier in the gel network supported chemical foaming agents of Examples 1-7 and Comparative Examples 1-4 are calculated and recorded in Table 1.

[0107] Table 1

[0108] As can be seen from Figure 1, the initial decomposition temperature of the gel network-supported chemical foaming agent in Example 1 is 50°C lower than that of the chemical foaming agent in Comparative Example 2. The initial decomposition temperature of the gel network-supported chemical foaming agent in Example 1 is more suitable for polyethylene foaming.

[0109] As can be seen from the results in Table 1, compared with Comparative Examples 1-4, the initial decomposition temperature of the examples using the chemical foaming agent described in this invention is more suitable for polyethylene foaming and molding.

[0110] Test Example 2

[0111] The gel network-supported chemical foaming agents prepared in Examples 1-7 and Comparative Examples 1-4 were tested for their polyethylene rotational molding performance. The test method is as follows: Polyethylene and gel network-supported chemical foaming agent were melt-blended at a mass ratio of 100:1.5. A twin-screw extruder with a diameter of 16 mm and an aspect ratio (L / R) of 40 was used for melt processing at 150 °C. The blend was then ground into powder at 60 °C for subsequent rotational molding tests. The rotational molding mold was 450 mm × 370 mm × 200 mm in size, the rotational molding temperature was 270 °C, and the heating time was set to 24 min. The rotational molding machine's main and secondary shaft speeds were set to 5 r / m and 8 r / m, respectively. The cell diameters of the polyethylene foam materials prepared with the gel network-supported chemical foaming agents of Examples 1-7 and Comparative Examples 1-4 were measured using a Micro-CT instrument, and the average cell diameters are recorded in Table 2. A comparison of the cell diameters of the polyethylene foam materials prepared with the gel network-supported chemical foaming agents of Example 1 and Comparative Example 2 is shown in Figure 2. The pore volumes of the polyethylene foam materials prepared with the gel network-supported chemical foaming agents of Examples 1-7 and Comparative Examples 1-4 were measured using a Micro-CT instrument, and the average pore volumes are recorded in Table 2. A comparison of the pore volumes of the polyethylene foam materials prepared with the gel network-supported chemical foaming agents of Example 1 and Comparative Example 2 is shown in Figure 3.

[0112] Table 2

[0113] As can be seen from Figure 2, the polyethylene foam material prepared by the chemical foaming agent in Comparative Example 2 has a cell diameter of less than 400 μm; the polyethylene foam material prepared by the gel network-supported chemical foaming agent in Example 1 has a cell diameter of less than 200 μm, and the vast majority of cells have a cell diameter of less than 100 μm.

[0114] As can be seen from Figure 3, the polyethylene foam material prepared by the chemical foaming agent in Comparative Example 2 has a small difference in pore volume compared with the polyethylene foam material prepared by the gel network-supported chemical foaming agent in Example 1, and the foaming effect is comparable.

[0115] As can be seen from the results in Table 3, compared with Comparative Examples 1-4, the polyethylene foam material prepared using the gel network-supported chemical foaming agent described in this invention has a smaller pore diameter and a better foaming effect.

[0116] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A gel network-supported chemical foaming agent, characterized in that, This gel network-supported chemical foaming agent contains a gel network carrier and azodicarbonamide loaded on the gel network carrier. Based on the total weight of the gel network-supported chemical foaming agent, the content of azodicarbonamide is 10-40% by weight, and the content of the gel network carrier is 60-90% by weight.

2. The gel network-supported chemical foaming agent according to claim 1, characterized in that, The azodicarbonamide has a particle size of 12-18 μm.

3. The gel network-supported chemical foaming agent according to claim 1 or 2, characterized in that, The gel network carrier is an aluminum-based gel network carrier and / or a silicon-based gel network carrier.

4. The gel network-supported chemical foaming agent according to any one of claims 1-3, characterized in that, The gel network carrier is a silicon-based gel network carrier.

5. A method for preparing a gel network-supported chemical foaming agent, characterized in that, The method includes the following steps: (1) Mix the sol and stabilizer and perform a first stirring to obtain a mixture; (2) The mixture and azodicarbonamide are mixed and subjected to ultrasonic treatment and second stirring in sequence to obtain a suspension; (3) The suspension is freeze-dried. The sol is an aluminum sol and / or a silica sol.

6. The method according to claim 5, characterized in that, The stabilizer is carboxymethyl cellulose.

7. The method according to claim 5 or 6, characterized in that, The mass ratio of the sol to the stabilizer is (80-130):

1.

8. The method according to any one of claims 5-7, characterized in that, The mass ratio of the silica sol to the stabilizer is (80-110):

1.

9. The method according to any one of claims 5-8, characterized in that, The mass ratio of the aluminum sol to the stabilizer is (110-130):

1.

10. The method according to any one of claims 5-9, characterized in that, The mass ratio of the sol to the azodicarbonamide is 1:(0.008-0.2).

11. The method according to any one of claims 5-10, characterized in that, The conditions for the first stirring include: a stirring rate of 800-1400 r / m and a stirring time of 2-4 h.

12. The method according to any one of claims 5-11, characterized in that, The conditions for the second stirring include: a stirring rate of 800-1400 r / m and a stirring time of 2-8 h.

13. The method according to any one of claims 5-12, characterized in that, The freeze-drying conditions include a temperature of -55 to -85°C and a time of 24 to 72 hours.

14. A gel network-supported chemical foaming agent prepared by the method according to any one of claims 5-13.

15. The application of the gel network-supported chemical foaming agent according to any one of claims 1-4 and 14 in polyethylene rotational molding.

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