Gel network supported chemical foaming agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of macromolecular polyethylene foaming materials, and discloses a gel network supported chemical foaming agent as well as a preparation method and application thereof. The gel network supported chemical foaming agent contains a gel network carrier and azodicarbonamide supported on the gel network carrier, and based on 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 the advantages of lower initial foaming temperature, controllable decomposition process, smaller cell size and better application value.

Description

Technical Field

[0001] The invention relates to the technical field of high molecular polyethylene foaming materials, and in particular to a gel network supported chemical foaming agent and a preparation method and application thereof. Background Art

[0002] The chemical foaming agents used in the manufacture of traditional polyolefin foam materials are limited by their single structure, violent decomposition reaction, and difficulty in controlling pore size, which seriously hinders the further optimization of material performance and functional expansion. In view of this, the research and development of composite foaming agent materials, especially those loaded foaming agent systems that can be controlled through multi-component design and precise pore structure, has become the focus of academic and industrial attention. Such systems can not only achieve precise control of the foaming mechanism through sophisticated synthesis strategies, but also indicate huge research value and application prospects, and are expected to open a new chapter in the field of foaming materials.

[0003] Supported catalyst systems are widely used and studied in the chemical industry, especially their significant advantages in providing abundant active sites, accelerating chemical reaction rates, and reducing activation energy. The design of supported foaming agents can draw on their successful experience. In such catalyst systems, the role of the carrier material is particularly important. It not only determines the dispersion and utilization of the catalyst, but also ensures the structural stability and durability under extreme reaction conditions. The careful selection of the carrier is also related to the selectivity and life of the catalyst, further highlighting its core role in building a high-performance catalytic system.

[0004] In recent years, gel, as a new type of material with high specific surface area, excellent thermal insulation and flame retardancy, has gradually attracted widespread attention from scientific researchers. Although gel has broad application prospects in many fields, its application as a carrier in polyolefin foaming materials, especially in controlling the formation of pores in the foaming process of complex large structures, is still a blank. Therefore, technological innovation around supported foaming agents for rotomolded polyethylene, especially through precise control of the thermal decomposition behavior and kinetics of the foaming agent, in order to achieve the optimization of polyethylene foaming effect and material properties, has become the key to current research, with the aim of overcoming existing technical difficulties, promoting the advancement of foaming technology and improving the quality of polyethylene foaming materials. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of the polyethylene foaming agent in the prior art that the decomposition temperature is too high and the decomposition process is uncontrollable, and to provide a gel network loaded chemical foaming agent and a preparation method and application thereof. The gel network loaded chemical foaming agent has a lower initial foaming temperature, a controllable decomposition process, a smaller pore size, and better application value.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a gel network-loaded chemical foaming agent, which contains a gel network carrier and azodicarbonamide loaded on the gel network carrier, wherein, based on the total weight of the gel network-loaded 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.

[0007] Preferably, the particle size of the azodicarbonamide is 12-18 μm.

[0008] Preferably, the gel network carrier is an aluminum-based gel network carrier and / or a silicon-based gel network carrier, preferably a silicon-based gel network carrier.

[0009] The second aspect of the present invention provides a method for preparing a gel network supported chemical foaming agent, the method comprising the following steps:

[0010] (1) mixing the sol and the stabilizer and performing a first stirring to obtain a mixture;

[0011] (2) mixing the mixture and azodicarbonamide and sequentially performing ultrasonic treatment and second stirring to obtain a suspension;

[0012] (3) freeze-drying the suspension,

[0013] Wherein, the sol is aluminum sol and / or silica sol.

[0014] Preferably, the stabilizer is carboxymethyl cellulose.

[0015] Preferably, the mass ratio of the sol to the stabilizer is (80-130):1.

[0016] Preferably, the mass ratio of the silica sol to the stabilizer is (80-110):1.

[0017] Preferably, the mass ratio of the aluminum sol to the stabilizer is (110-130):1.

[0018] Preferably, the mass ratio of the sol to the azodicarbonamide is 1:(0.008-0.2).

[0019] Preferably, the first stirring conditions include: a stirring rate of 800-1400 r / m and a time of 2-4 h.

[0020] Preferably, the second stirring conditions include: a stirring rate of 800-1400 r / m and a time of 2-8 h.

[0021] Preferably, the freeze-drying conditions include: a temperature of -55 to -85°C and a time of 24 to 72 hours.

[0022] The third aspect of the present invention provides a gel network supported chemical foaming agent prepared by the above method.

[0023] The fourth aspect of the present invention provides the use of the above-mentioned gel network supported chemical foaming agent in polyethylene rotational foaming molding.

[0024] The gel network supported chemical foaming agent of the present invention is different from the chemical foaming agent in the prior art in terms of foaming mechanism and technical effect, as follows:

[0025] (1) The gel network carrier has an organic structure and can completely encapsulate azodicarbonamide. This encapsulation not only improves the dispersibility of azodicarbonamide, making the foaming effect more uniform and delicate, but also effectively prevents the agglomeration of azodicarbonamide, thereby enhancing its stability;

[0026] (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 stability of the foaming ratio and the foaming effect;

[0027] (3) The gel network-loaded chemical foaming agent of the present invention effectively reduces the initial decomposition temperature of the azodicarbonamide foaming agent and slows down its thermal decomposition rate. This regulatory effect makes the foaming process more controllable and facilitates the adjustment of the foaming speed and foaming ratio according to actual needs; at the same time, it reduces the initial decomposition temperature and slows down the thermal decomposition rate, thereby helping to improve the use effect of azodicarbonamide in rotational molding foaming. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a thermogravimetric analysis diagram of the gel network supported chemical foaming agent prepared in Example 1 and Comparative Example 2;

[0029] Figure 2 It is a comparison diagram of the cell diameters of polyethylene foam materials prepared by gel network supported chemical foaming agents of Example 1 and Comparative Example 2;

[0030] Figure 3 It is a comparison chart of the pore volumes of polyethylene foam materials prepared by gel network supported chemical foaming agents of Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0033] The gel network loaded chemical foaming agent of the present invention contains a gel network carrier and azodicarbonamide loaded on the gel network carrier, wherein, based on the total weight of the gel network loaded 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 loaded chemical foaming agent of the present invention, the dispersibility of azodicarbonamide is improved by the gel network carrier, the pores are made more uniform, and the foaming effect is improved; the thermal influence of the decomposition reaction is reduced by the gel network carrier, the temperature fluctuation in the foaming process is more stable, which is conducive to the uniform decomposition of azodicarbonamide, and then the stability of the foaming ratio and the foaming effect is improved; the decomposition temperature is reduced by the gel network carrier, and its thermal decomposition rate is slowed down, so that the foaming process is more controllable, and the pore size formed in the polyethylene rotational molding foaming molding process is small, and the pore diameter is less than 200μm, which has better application value.

[0034] In the gel network supported chemical foaming agent of the present 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. The particle size range of the azodicarbonamide is conducive to preparing a more uniform pore distribution and obtaining a better foaming effect.

[0035] In the gel network-loaded chemical foaming agent described in the present invention, the foaming effect and stability are improved by regulating the thermal decomposition process. The gel network carrier is preferably an aluminum-based gel network carrier and / or a silicon-based gel network carrier, more preferably a silicon-based gel network carrier.

[0036] In some embodiments, the gel network loaded chemical foaming agent of the present invention contains a gel network carrier and azodicarbonamide loaded on the gel network carrier, wherein, based on the total weight of the gel network loaded 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; 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.

[0037] The present invention also provides a method for preparing a gel network supported chemical foaming agent, the method comprising the following steps:

[0038] (1) mixing the sol and the stabilizer and performing a first stirring to obtain a mixture;

[0039] (2) mixing the mixture and azodicarbonamide and sequentially performing ultrasonic treatment and second stirring to obtain a suspension;

[0040] (3) freeze-drying the suspension,

[0041] Wherein, the sol is aluminum sol and / or silica sol.

[0042] According to the method of the present invention, azodicarbonamide is loaded onto a gel network carrier by freeze drying, thereby improving the dispersibility of azodicarbonamide, making the pores more uniform and improving the foaming effect; and reducing the initial decomposition temperature, making the initial foaming temperature in the polyethylene foaming molding process more suitable and more controllable, which is conducive to preparing a more uniform pore distribution and obtaining a better foaming effect.

[0043] In the method of the present invention, in order 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.

[0044] In the method described in the present 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 for example, 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 may be 1:(0.03-0.2), preferably 1:(0.03-0.12). The mass ratio of the aluminum sol to the azodicarbonamide may be 1:(0.008-0.053), preferably 1:(0.016-0.024).

[0045] In the method of the present invention, the first stirring conditions include: the temperature can be 20-40°C, preferably 20-30°C; the stirring rate can be 800-1400r / m, preferably 1200-1400r / m; the time can be 2-4h, preferably 3-4h.

[0046] In the method described in the present invention, in order to obtain an azodicarbonamide-supported structure and thus improve the foaming effect, the ultrasonic treatment time is preferably 25-40 min, more preferably 30-40 min.

[0047] In the method of the present invention, the second stirring conditions include: the temperature can be 20-40°C, preferably 20-30°C; the stirring rate can be 800-1400r / m, preferably 1200-1400r / m; the time can be 2-8h, preferably 6-8h.

[0048] In the method of the present invention, the freeze-drying conditions include: the temperature can be -55 to -85°C, preferably -75 to -85°C; the time can be 24-72h, preferably 48-72h.

[0049] In some embodiments, the method for preparing the gel network supported chemical foaming agent of the present invention comprises the following steps:

[0050] (1) mixing the sol and the stabilizer and performing a first stirring at 20-40° C. and a stirring rate of 800-1400 r / m for 2-4 h to obtain a mixture;

[0051] (2) mixing the mixture and azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 25-40 min and second stirring at a stirring rate of 800-1400 r / m at 20-40° C. for 2-8 h to obtain a suspension;

[0052] (3) freeze-drying the suspension at -55 to -85°C for 24 to 72 hours,

[0053] Wherein, the sol is aluminum sol and / or 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 sol to the stabilizer is (80-130):1; the mass ratio of the sol to the azodicarbonamide is 1:(0.008-0.2).

[0054] In other embodiments, the method for preparing the gel network supported chemical foaming agent of the present invention comprises the following steps:

[0055] (1) mixing the sol and the stabilizer and performing a first stirring at 20-30° C. and a stirring rate of 1200-1400 r / m for 3-4 hours to obtain a mixture;

[0056] (2) mixing the mixture and azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30-40 min and second stirring at a stirring rate of 1200-1400 r / m at 20-30° C. for 6-8 h to obtain a suspension;

[0057] (3) freeze-drying the suspension at -75 to -85°C for 48 to 72 hours,

[0058] Wherein, the sol is aluminum sol and / or 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).

[0059] The present invention also provides a gel network supported chemical foaming agent prepared by the above method. According to the gel network supported chemical foaming agent of the present invention, the dispersibility of azodicarbonamide is improved, and the agglomeration of azodicarbonamide particles is effectively prevented, thereby enhancing its stability; the initial decomposition temperature of azodicarbonamide is effectively reduced, and its thermal decomposition rate is slowed down; a thermal barrier effect is formed, and the thermal impact of the decomposition reaction of azodicarbonamide is reduced.

[0060] The present invention also provides the application of the above-mentioned gel network loaded chemical foaming agent in polyethylene rotational molding and foaming. According to the application described in the present invention, in polyethylene rotational molding and foaming, the initial decomposition temperature of the gel network loaded chemical foaming agent described in the present invention is about 160°C, and the temperature is more suitable. At this time, the polyethylene melt viscosity is high, and it has both good fluidity and a certain viscosity. The bubbles formed are smaller and more uniform, which improves the foaming effect. When the temperature is too high, the polyethylene viscosity is low, the bubbles formed are large, and the bubble fusion phenomenon is prone to occur. Moreover, the foaming effect of the gel network loaded chemical foaming agent described in the present invention is more uniform and delicate, which improves the stability of the foaming ratio and the foaming effect, and the foaming process is more controllable, which is convenient for adjusting the foaming speed and the foaming ratio according to actual needs.

[0061] The following examples further illustrate the gel network supported chemical foaming agent and its preparation method and application. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0062] The experimental methods in the following examples are all conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are all commercially available unless otherwise specified. The azodicarbonamide used in the examples was purchased from Adamas Reagent Co., Ltd. with a particle size of 12-18 μm; the silica sol used in the examples was purchased from Guangdong Huierte Nano Technology Co., Ltd. with a solid content of 30%; the aluminum sol used in the examples was purchased from Zibo Jinqi Chemical Technology Co., Ltd. with a brand name of LA-10 and a solid content of 8%. The carboxymethyl cellulose used in the examples was purchased from Beijing Inokai Technology Co., Ltd. and was analytically pure.

[0063] Example 1

[0064] (1) 40 g of silica sol and 0.4 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 1000 r / m at 25° C. to obtain a mixture;

[0065] (2) mixing the mixture obtained in step (1) with 4.8 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30 min and second stirring at a stirring rate of 1000 r / m at 25° C. for 8 h to obtain a suspension;

[0066] (3) freeze-drying the suspension obtained in step (2) at -60°C for 24 hours to obtain a gel network-supported chemical foaming agent.

[0067] Example 2

[0068] (1) 80 g of silica sol and 0.8 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 1000 r / m at 25° C. to obtain a mixture;

[0069] (2) mixing the mixture obtained in step (1) with 3.6 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30 min and second stirring at a stirring rate of 1000 r / m at 25° C. for 8 h to obtain a suspension;

[0070] (3) freeze-drying the suspension obtained in step (2) at -60°C for 48 hours to obtain a gel network-supported chemical foaming agent.

[0071] Example 3

[0072] (1) 100 g of silica sol and 1.2 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 1400 rpm at 35° C. to obtain a mixture;

[0073] (2) mixing the mixture obtained in step (1) with 3.6 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30 min and second stirring at 35° C. at a stirring rate of 1400 r / m for 8 h to obtain a suspension;

[0074] (3) freeze-drying the suspension obtained in step (2) at -80°C for 72 hours to obtain a gel network-supported chemical foaming agent.

[0075] Example 4

[0076] (1) 75 g of aluminum sol and 0.6 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 1400 rpm at 35° C. to obtain a mixture;

[0077] (2) mixing the mixture obtained in step (1) with 1.2 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30 min and second stirring at 35° C. at a stirring rate of 1400 r / m for 8 h to obtain a suspension;

[0078] (3) freeze-drying the suspension obtained in step (2) at -80°C for 72 hours to obtain a gel network-supported chemical foaming agent.

[0079] Example 5

[0080] (1) 150 g of aluminum sol and 1.2 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 1400 rpm at 35° C. to obtain a mixture;

[0081] (2) mixing the mixture obtained in step (1) with 3.6 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30 min and second stirring at 35° C. at a stirring rate of 1400 r / m for 8 h to obtain a suspension;

[0082] (3) freeze-drying the suspension obtained in step (2) at -80°C for 72 hours to obtain a gel network-supported chemical foaming agent.

[0083] Example 6

[0084] (1) 64 g of silica sol and 0.8 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 800 rpm at 20° C. to obtain a mixture;

[0085] (2) mixing the mixture obtained in step (1) with 12.8 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 40 min and second stirring at a stirring rate of 800 r / m at 20° C. for 6 h to obtain a suspension;

[0086] (3) freeze-drying the suspension obtained in step (2) at -55°C for 72 hours to obtain a gel network-loaded chemical foaming agent.

[0087] Example 7

[0088] (1) 64 g of aluminum sol and 0.8 g of carboxymethyl cellulose were mixed and stirred for 2 h at a stirring rate of 1400 rpm at 40° C. to obtain a mixture;

[0089] (2) mixing the mixture obtained in step (1) with 0.6 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 25 min and second stirring at 40° C. at a stirring rate of 1400 r / m for 2 h to obtain a suspension;

[0090] (3) freeze-drying the suspension obtained in step (2) at -85°C for 72 hours to obtain a gel network-loaded chemical foaming agent.

[0091] Comparative Example 1

[0092] (1) 48 g of silica sol and 0.048 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 1000 rpm at 25° C. to obtain a mixture;

[0093] (2) mixing the mixture obtained in step (1) with 40 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30 min and second stirring at a stirring rate of 1000 r / m at 25° C. for 8 h to obtain a suspension;

[0094] (3) freeze-drying the suspension obtained in step (2) at -60°C for 24 hours to obtain a gel network-supported chemical foaming agent.

[0095] Comparative Example 2

[0096] The purchased azodicarbonamide was directly used as a chemical blowing agent.

[0097] Comparative Example 3

[0098] (1) 40 g of silica sol and 0.4 g of carboxymethyl cellulose were mixed and stirred for 4 h at a stirring rate of 1000 r / m at 25° C. to obtain a mixture;

[0099] (2) mixing the mixture obtained in step (1) with 0.6 g of azodicarbonamide and sequentially subjecting the mixture to ultrasonic treatment for 30 min and second stirring at a stirring rate of 1000 r / m at 25° C. for 8 h to obtain a suspension;

[0100] (3) freeze-drying the suspension obtained in step (2) at -60°C for 24 hours to obtain a gel network-supported chemical foaming agent.

[0101] Comparative Example 4

[0102] A 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 h to obtain a gel network supported chemical foaming agent.

[0103] Test Example 1

[0104] The gel network supported chemical foaming agents prepared in Examples 1-7 and Comparative Examples 1-4 were subjected to thermogravimetric analysis by a thermogravimetric analyzer. The thermogravimetric analysis method was based on the national standard GB / T 17050-1997 "Thermal Radiation Terminology". The thermogravimetric analysis graphs of the gel network supported chemical foaming agents prepared in Example 1 and Comparative Example 2 were as follows: Figure 1 As shown; the measured 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; and the mass proportions of azodicarbonamide and the gel network carrier in the gel network supported chemical foaming agent of Examples 1-7 and Comparative Examples 1-4 are calculated and recorded in Table 1.

[0105] Table 1

[0106]

[0107] Depend on Figure 1 It can be seen that the initial decomposition temperature of the gel network-supported chemical foaming agent of Example 1 is 50° C. lower than that of the chemical foaming agent of Comparative Example 2. The initial decomposition temperature of the gel network-supported chemical foaming agent of Example 1 is more suitable for polyethylene foaming molding.

[0108] It can be seen from the results in Table 1 that, compared with Comparative Examples 1-4, the initial decomposition temperature of the embodiment using the chemical foaming agent of the present invention is more suitable for polyethylene foaming molding.

[0109] Test Example 2

[0110] The polyethylene rotational molding foaming performance of the gel network loaded chemical foaming agent prepared in Examples 1-7 and Comparative Examples 1-4 was tested, and the test method was as follows: polyethylene and the gel network loaded chemical foaming agent were melt blended in a mass ratio of 100:1.5, and a twin-screw extruder with a diameter of 16 mm and a length-to-diameter ratio (L / R) of 40 was used for melt processing at 150°C, and then the blend was ground into powder at 60°C for subsequent rotational molding foaming processing and molding tests. The size of the rotational molding experimental mold was 450mm×370mm×200mm, the rotational molding processing temperature was 270°C, and the heating time was set to 24min. The rotational speeds of the main shaft and the secondary shaft of the rotomolding machine were set to 5 r / m and 8 r / m, respectively; the pore diameters of the polyethylene foam materials prepared by the gel network-loaded chemical foaming agents of Examples 1-7 and Comparative Examples 1-4 were measured by a Micro-CT instrument, and the average pore diameters were recorded in Table 2, and the pore diameter comparison diagram of the polyethylene foam materials prepared by the gel network-loaded chemical foaming agents of Example 1 and Comparative Example 2 is shown in Table 2. Figure 2 The pore volumes of polyethylene foam materials prepared by gel network supported chemical foaming agents of Examples 1-7 and Comparative Examples 1-4 were measured by Micro-CT instrument, and the average pore volumes were recorded in Table 2. The pore volume comparison diagram of polyethylene foam materials prepared by gel network supported chemical foaming agents of Example 1 and Comparative Example 2 is shown in Table 2. Figure 3 shown.

[0111] Table 2

[0112] serial number Average cell diameter (μm) <![CDATA[Pore volume (μm 3 )]]> Example 1 98 <![CDATA[6.16×10 10 ]]> Example 2 142 <![CDATA[5.72×10 10 ]]> Example 3 163 <![CDATA[5.16×10 10 ]]> Example 4 135 <![CDATA[5.23×10 10 ]]> Example 5 121 <![CDATA[5.91×10 10 ]]> Example 6 107 <![CDATA[6.03×10 10 ]]> Example 7 159 <![CDATA[5.21×10 10 ]]> Comparative Example 1 282 <![CDATA[3.75×10 10 ]]> Comparative Example 2 339 <![CDATA[3.26×10 10 ]]> Comparative Example 3 331 <![CDATA[3.31×10 10 ]]> Comparative Example 4 256 <![CDATA[3.82×10 10 ]]>

[0113] Depend on Figure 2 It can be seen that the pore diameter of the polyethylene foam material prepared by the chemical foaming agent of Comparative Example 2 is less than 400 μm; the pore diameter of the polyethylene foam material prepared by the gel network-loaded chemical foaming agent of Example 1 is less than 200 μm, and the vast majority of the pore diameters are less than 100 μm.

[0114] Depend on Figure 3 It can be seen that the pore volume of the polyethylene foam material prepared by the chemical foaming agent of Comparative Example 2 and the polyethylene foam material prepared by the gel network-loaded chemical foaming agent of Example 1 is slightly different, and the foaming effects are equivalent.

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

[0116] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A gel network supported chemical foaming agent, characterized in that: The gel network supported chemical foaming agent comprises 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.

2. The gel network supported chemical foaming agent according to claim 1, characterized in that: The particle size of the azodicarbonamide is 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, preferably a silicon-based gel network carrier.

4. A method for preparing a gel network supported chemical foaming agent, characterized in that: The method comprises the following steps: (1) mixing the sol and the stabilizer and performing a first stirring to obtain a mixture; (2) mixing the mixture and azodicarbonamide and sequentially performing ultrasonic treatment and second stirring to obtain a suspension; (3) freeze-drying the suspension, Wherein, the sol is aluminum sol and / or silica sol.

5. The method according to claim 4, characterized in that The stabilizer is carboxymethyl cellulose.

6. The method according to claim 4 or 5, characterized in that: The mass ratio of the sol to the stabilizer is (80-130):1; Preferably, the mass ratio of the silica sol to the stabilizer is (80-110):1; Preferably, the mass ratio of the aluminum sol to the stabilizer is (110-130):

1.

7. The method according to any one of claims 4 to 6, characterized in that: The mass ratio of the sol to the azodicarbonamide is 1:(0.008-0.2).

8. The method according to any one of claims 4 to 7, characterized in that: The first stirring conditions include: a stirring rate of 800-1400 r / m and a time of 2-4 h; The second stirring conditions include: a stirring rate of 800-1400 r / m and a time of 2-8 h.

9. The method according to any one of claims 4 to 7, characterized in that: The freeze-drying conditions include: a temperature of -55 to -85°C and a time of 24 to 72 hours.

10. A gel network supported chemical foaming agent prepared by the method according to any one of claims 4 to 9.

11. Use of the gel network supported chemical foaming agent according to any one of claims 1 to 3 and 10 in polyethylene rotational foaming molding.

Images