阅读说明：本技术 一种丙烯酸树脂热膨胀物理发泡微球及辐照制备方法 (Acrylic resin thermal expansion physical foaming microsphere and irradiation preparation method ) 是由 陈海贤 吴超 魏增 于 2020-12-24 设计创作，主要内容包括：本发明属于高分子辐照聚合领域,具体涉及一种丙烯酸树脂热膨胀物理发泡微球及辐照聚合制备方法。本发明以甲基丙烯酸甲酯为主单体,以甲基丙烯酸二环戊基酯、N-乙基丙烯酰胺等为助单体,常温常压下,以电子加速器辐照共聚制备了基于丙烯酸树脂的物理热膨胀发泡微球,具有单体利用率高、无需加入过氧化物引发剂、所用设备以及生产工艺简单操作方便的特点。(The invention belongs to the field of high-molecular irradiation polymerization, and particularly relates to acrylic resin thermal-expansion physical foaming microspheres and an irradiation polymerization preparation method. The invention takes methyl methacrylate as a main monomer, takes dicyclopentyl methacrylate, N-ethyl acrylamide and the like as auxiliary monomers, and adopts an electron accelerator for irradiation copolymerization at normal temperature and normal pressure to prepare the physical thermal expansion foaming microsphere based on acrylic resin.)

1. The acrylic resin thermal expansion physical foaming microsphere is characterized in that: the formula of the microspheres in mass ratio is as follows: 190 parts of polymethyl methacrylate 170-5 parts of polycyclopentyl methacrylate, 1-5 parts of poly N-ethyl acrylamide, 50-80 parts of foaming agent, 0.2-4 parts of crosslinking agent and 5-80KGy radiation dose.

2. An irradiation preparation method of acrylic resin thermal expansion physical foaming microspheres is characterized in that: the method comprises the following steps:

(1) 190 parts of methyl methacrylate 170-5-30 parts of dicyclopentanyl methacrylate, 1-5 parts of N-ethyl acrylamide, 50-80 parts of foaming agent and 0.2-4 parts of cross-linking agent are uniformly mixed at 0 ℃ to prepare oil phase solution, and nitrogen is introduced into the oil phase solution to be bubbled and deoxidized for 5 minutes;

(2) dissolving 0.5 percent of polyvinyl alcohol 1788, 5.0 thousandth of OP-10 and 5.0 percent of sodium chloride in 3000 parts of 1600-fold deionized water by mass ratio, fully stirring until the materials are completely dissolved to prepare an aqueous phase solution, and introducing nitrogen into the aqueous phase solution for bubbling and deoxidizing for 10 minutes;

(3) vacuumizing a stainless steel reactor with mechanical stirring, filling nitrogen to remove air in a reaction system, adding the water phase obtained in the step (2) into the reactor under the protection of the nitrogen, and adding the oil phase obtained in the step (1); starting stirring, controlling the rotation speed to be 200-800rpm, irradiating for 5-30min under an electron accelerator, and then keeping the reaction system for polymerization reaction for 4-22 hours at normal temperature and stopping the reaction;

(4) and opening the reactor, taking out the reaction product, performing centrifugal separation, washing with deionized water, performing centrifugal separation again, repeating the steps for three times, and drying at normal temperature to obtain the acrylic acid thermal expansion resin physical foaming microspheres.

3. The irradiation preparation method of the acrylic resin thermal expansion physical foaming microsphere as claimed in claim 2, characterized in that: the foaming agent is one or a composition of any two or more of n-pentane, isopentane, cyclohexane, neopentane, isohexane and n-hexane.

4. The irradiation preparation method of the acrylic resin thermal expansion physical foaming microsphere as claimed in claim 2, characterized in that: the cross-linking agent is one or a composition of two of 1, 3-butanediol dimethacrylate and 1, 4-butanediol dimethacrylate in any proportion.

5. The irradiation preparation method of the acrylic resin thermal expansion physical foaming microsphere as claimed in claim 2, characterized in that: the parameters of the electron accelerator are set as electron beam energy 10MeV, beam current 1.5-2mA and rated power 15-20 KW.

6. The irradiation preparation method of the acrylic resin thermal expansion physical foaming microsphere as claimed in claim 2, characterized in that: the polymerization stirring rate was 200 and 800 rpm.

Technical Field

The invention relates to the field of high-molecular irradiation polymerization, and mainly relates to acrylic resin thermal-expansion physical foaming microspheres and an irradiation preparation method.

Background

The thermal expansion physical foaming microsphere is a microsphere particle which has a core-shell structure and can be expanded and foamed after being heated to a certain temperature, the core contains low boiling point alkane as a foaming agent, and the shell is a thermoplastic high molecular polymer. When the external heating temperature is higher than the glass transition temperature of the thermoplastic polymer shell, the polymer shell is heated and softened, meanwhile, the alkane with low boiling point inside is heated and vaporized to generate internal pressure, and under the action of the internal pressure, the microspheres rapidly expand, and the volume is obviously increased. After cooling, the temperature is reduced to below the glass transition temperature of the polymer, and the microspheres can still maintain the expanded form and can not shrink obviously. The research on the thermal expansion physical foaming microspheres in China is late, and the thermal expansion physical foaming microspheres are mainly prepared in a chemical initiation suspension copolymerization mode. Tylen et al prepared high temperature physically foamed microcapsules containing acrylonitrile and glycidyl methacrylate (GAM). Mukly et al synthesized acrylonitrile-containing thermally expandable microspheres with N, N-Dimethylacrylamide (DMAA) in 2012. In 2013, Zhu Xiaojie and the like report a synthesis method and foaming performance research of high-temperature foaming microspheres containing acrylonitrile and methacrylic acid (MAA). Ji et al invented a method for synthesizing thermally expandable microspheres from acrylonitrile and Methyl Acrylate (MA) as main monomers (CN 104140549A). 2016, Wangjie and the like prepare the physical thermal expansion foaming microspheres by a suspension polymerization method. In the existing thermal expansion physical foaming microsphere technology at home and abroad, a chemical initiation and 40-100 ℃ pressurization suspension polymerization process (such as the technologies disclosed by CN106832110A, CN107915799A, CN104014287B, CN108314756A, CN103665419B, CN103665419A and CN 102633936B) is mostly adopted, so that the problems of complex process, high reaction energy consumption, low safety coefficient of peroxide initiator and the like exist, the production cost is increased for enterprises, and the problems hinder the large-scale industrial production of the domestic high-quality thermal expansion physical foaming microsphere to a certain extent.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a thermal expansion physical foaming microsphere of acrylic resin and an irradiation preparation method.

The object of the present invention is achieved by the following technical means. The acrylic resin thermal expansion physical foaming microsphere comprises the following components in percentage by mass: 190 parts of polymethyl methacrylate 170-5 parts of polycyclopentyl methacrylate, 1-5 parts of poly N-ethyl acrylamide, 50-80 parts of foaming agent, 0.2-4 parts of crosslinking agent and 5-80KGy radiation dose.

The invention discloses a radiation polymerization preparation method of acrylic resin thermal expansion physical foaming microspheres, which comprises the following steps:

(1) 190 parts of methyl methacrylate 170-5-30 parts of dicyclopentanyl methacrylate, 1-5 parts of N-ethyl acrylamide, 50-80 parts of foaming agent and 0.2-4 parts of cross-linking agent are uniformly mixed at 0 ℃ to prepare oil phase solution, and nitrogen is introduced into the oil phase solution to be bubbled and deoxidized for 5 minutes;

(2) dissolving 0.5 percent of polyvinyl alcohol 1788, 5.0 thousandth of OP-10 and 5.0 percent of sodium chloride in 3000 parts of 1600-fold deionized water by mass ratio, fully stirring until the materials are completely dissolved to prepare an aqueous phase solution, and introducing nitrogen into the aqueous phase solution for bubbling and deoxidizing for 10 minutes;

(3) vacuumizing a stainless steel reactor with mechanical stirring, filling nitrogen to remove air in a reaction system, adding the water phase obtained in the step (2) into the reactor under the protection of the nitrogen, and adding the oil phase obtained in the step (1); starting stirring, controlling the rotation speed to be 200-800rpm, irradiating for 5-30min under an electron accelerator, and then keeping the reaction system for polymerization reaction for 4-22 hours at normal temperature and stopping the reaction;

(4) and opening the reactor, taking out the reaction product, performing centrifugal separation, washing with deionized water, performing centrifugal separation again, repeating the steps for three times, and drying at normal temperature to obtain the acrylic acid thermal expansion resin physical foaming microspheres.

Furthermore, the foaming agent is one or a combination of any two or more of n-pentane, isopentane, cyclohexane, neopentane, isohexane and n-hexane.

Furthermore, the cross-linking agent is one or a composition of two of 1, 3-butanediol dimethacrylate and 1, 4-butanediol dimethacrylate in any proportion.

Furthermore, the parameters of the electron accelerator are set to be electron beam energy of 10MeV, beam current of 1.5-2mA and rated power of 15-20 KW.

Further, the polymerization stirring rate was 200-800 rpm.

The invention has the beneficial effects that: the invention aims to rely on a normal-temperature and normal-pressure irradiation polymerization process, methyl methacrylate is used as a main monomer, and is copolymerized with dicyclopentyl methacrylate and a small amount of N-ethyl acrylamide monomer to carry out polymerization reaction under normal-temperature and normal-pressure conditions, so that the defects of a heating and pressurizing polymerization process are avoided, and the thermal expansion physical foaming microsphere with stable foaming performance based on acrylic resin is prepared.

Drawings

FIG. 1 is a photograph showing a comparison of the microspheres of the present invention before and after foaming.

Detailed Description

The invention will be described in detail below with reference to the following drawings:

the experimental steps are as follows:

I. treatment of experimental raw materials: and (3) purifying the methyl methacrylate, the dicyclopentyl methacrylate and the N-ethyl acrylamide by reduced pressure distillation, sealing and storing in a refrigerator for later use.

II. polymerization step:

(1) 190 parts of methyl methacrylate 170-5 parts, 5-30 parts of dicyclopentanyl methacrylate, 1-5 parts of N-ethyl acrylamide, 50-80 parts of foaming agent and 0.2-4 parts of cross-linking agent are uniformly mixed at 0 ℃ to prepare oil phase solution, and nitrogen is introduced into the oil phase solution to be bubbled and deoxidized for 5 minutes.

(2) Dissolving 0.5 percent of polyvinyl alcohol 1788, 5.0 thousandth of OP-10 and 5.0 percent of sodium chloride in 3000 parts of 1600-fold deionized water, fully stirring until the polyvinyl alcohol, the OP-10 and the sodium chloride are completely dissolved to prepare an aqueous phase solution, and introducing nitrogen into the aqueous phase solution to carry out bubbling and deoxygenation for 10 minutes.

(3) The stainless steel reactor with mechanical stirring was evacuated and then purged with nitrogen to remove air from the reaction system. And (3) adding the water phase obtained in the step (2) into the reactor under the protection of nitrogen, and then adding the oil phase obtained in the step (1). Starting stirring, controlling the rotation speed to be 200-800rpm, irradiating for 5-30min under an electron accelerator, and then stopping reaction after keeping the reaction system reacting for 4-22 hours at normal temperature.

Treatment of the polymerization product: and opening the reactor, taking out the reaction product, performing centrifugal separation, washing with deionized water, performing centrifugal separation again, repeating for three times, and drying at normal temperature to obtain the acrylic resin physical foaming microspheres.

Characterization and testing:

and IV, observing the morphology of the microspheres before and after foaming: and placing a small amount of dried microsphere product on a glass slide of a hot stage microscope, adjusting an ocular lens and an objective lens, and observing the form and the size of the microsphere.

V, measuring the expansion rate of the microspheres: and (3) measuring the volumes of the microspheres before and after foaming by using a glass test tube with fine scales at a set temperature, and calculating the expansion ratio.

Example 1

The specific experimental procedures for preparing microspheres are detailed in [ I-III ]. The raw material formula composition and the synthesis process conditions are as follows: methyl methacrylate: 9g, dicyclopentyl methacrylate: 1g, N-ethylacrylamide: 0.5g, isopentane: 6mL, 1, 4-butanediol dimethacrylate: 10 μ L, aqueous phase: 120 mL; stirring speed: 200rpm, radiation dose: 80KGy, radiation reaction time: 5min, normal-temperature reaction time: and (4) 18 h. The characterization and the test of the microspheres are detailed in IV-V, and the characterization test result shows that: the prepared microspheres are of a core-shell structure, the average particle size is 145 microns, the concentrated foaming temperature of the microspheres is 85 ℃, and the expansion ratio is 14 times; the microspheres are broken in the foaming process, the microspheres retract after foaming, and the dispersibility of the microspheres after foaming is poor.

Example 2

The specific experimental procedures for preparing microspheres are detailed in [ I-III ]. The raw material formula composition and the synthesis process conditions are as follows: methyl methacrylate: 9g, dicyclopentyl methacrylate: 1g, N-ethylacrylamide: 0.5g, neopentane: 6mL, 1, 3-butylene glycol dimethacrylate: 40 μ L, aqueous phase: 120 mL; stirring speed: 800rpm, radiation dose: 5KGy, radiation reaction time: 0.5h, normal-temperature reaction time: and (4) 18 h. The characterization and the test of the microspheres are detailed in IV-V, and the characterization test result shows that: the prepared microspheres are of a core-shell structure, the average particle size is 30 mu m, the concentrated foaming temperature of the microspheres is 145 ℃, and the expansion ratio is 4 times; few microspheres are broken in the foaming process, the microspheres do not retract after foaming, and the dispersibility of the microspheres after foaming is good.

Example 3

The specific experimental procedures for preparing microspheres are detailed in [ I-III ]. The raw material formula composition and the synthesis process conditions are as follows: methyl methacrylate: 10g of dicyclopentyl methacrylate; 1.5g, N-ethylacrylamide: 0.25g, isopentane: 4mL, 1, 4-butanediol dimethacrylate: 40 μ L, aqueous phase: 120 mL; stirring speed: 400rpm, radiation dose: 30KGy, radiation reaction time: 0.25h, normal-temperature reaction time: and (4) 22 h. The characterization and the test of the microspheres are detailed in IV-V, and the characterization test result shows that: the prepared microspheres are of a core-shell structure, the average particle size is 84 mu m, the concentrated foaming temperature of the microspheres is 95 ℃, and the expansion ratio is 8 times; a few microspheres are broken in the heating foaming process, the microspheres retract after foaming, and the dispersibility of the microspheres after foaming is poor.

Example 4

The specific experimental procedures for preparing microspheres are detailed in [ I-III ]. The raw material formula composition and the synthesis process conditions are as follows: methyl methacrylate: 9g, dicyclopentyl methacrylate: 1g, N-ethylacrylamide: 0.25g, isopentane: 6mL, 1, 3-butylene glycol dimethacrylate: 20 μ L, 1, 4-butanediol dimethacrylate: 40 μ L, aqueous phase: 120 mL; stirring speed: 400rpm, radiation dose: 60KGy, radiation reaction time: 0.5h, normal-temperature reaction time: and (4) 22 h. The characterization and the test of the microspheres are detailed in IV-V, and the characterization test result shows that: the prepared microspheres are in a core-shell structure, the particle size distribution is uniform, and the average particle size is 60 mu m; the centralized foaming temperature of the microspheres is 150 ℃, and the expansion ratio reaches 25 times; the microspheres are not broken in the foaming process, the microspheres are not retracted after foaming, the comprehensive foaming performance is good, and the comparison photos before and after foaming of the microspheres are shown in figure 1.

Example 5

The specific experimental procedures for preparing microspheres are detailed in [ I-III ]. The raw material formula composition and the synthesis process conditions are as follows: methyl methacrylate: 9g, dicyclopentyl methacrylate: 2g, N-ethylacrylamide: 0.25g, n-hexane: 10mL, 1, 4-butanediol dimethacrylate: 40 μ L, aqueous phase: 80 mL; stirring speed: 400rpm, radiation dose: 60KGy, radiation reaction time: 0.5h, normal-temperature reaction time: and (4) 22 h. The characterization and the test of the microspheres are detailed in IV-V, and the characterization test result shows that: the prepared microsphere has unobvious core-shell structure, irregular shape, uneven particle size distribution and average particle size of 76 mu m; the centralized foaming temperature of the microspheres is 104 ℃, and the expansion ratio is 5 times; the microspheres are partially broken in the foaming process and retract after foaming, and the dispersibility of the microspheres after foaming is poor.

Finally, many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.