Composite initiator capable of improving stability of polymerization process and preparation method thereof

Abstract

The invention discloses a composite initiator capable of improving the stability of a polymerization process. The composite initiator comprises oxidoreductase and an azo initiator. The invention also provides a preparation method of the composite initiator. The oxidoreductase-azo composite initiator disclosed by the invention has a better and more stable initiation effect and can stably provide free radicals in an aqueous solution polymerization system, and the free radicals excited by oxidoreductase part can provide an initial temperature for a polymerization reaction and enable a subsequent azo part to be continuously initiated, so that the stability of a polymerization process is greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials, and in particular relates to a composite initiator capable of improving the stability of a polymerization process and a preparation method thereof. Background Art

[0002] Polyacrylamide (PAM) is an important water-soluble polymer compound, which is widely used in oil extraction, water treatment, papermaking, mining, metallurgy, environmental protection, building materials, coatings, food and other fields. It is mainly synthesized from acrylamide (AM) monomers through free radical polymerization.

[0003] The production process of polyacrylamide mainly includes homogeneous aqueous solution polymerization, inverse emulsion polymerization and inverse suspension polymerization. In addition, there are technical improvement methods such as chemical initiation system, radiation polymerization and UV light polymerization. The selection and optimization of these processes directly affect the molecular weight, solubility and application performance of polyacrylamide.

[0004] Polymerization initiators are a class of compounds used to start polymerization reactions and are widely used in various types of polymerization reactions, including free radical polymerization, ionic polymerization, and coordination polymerization. According to the type and mechanism of action of the initiator, it can be divided into the following categories: (1) Free radical polymerization initiators generate primary free radicals through thermal decomposition or photodecomposition, thereby initiating free radical polymerization and copolymerization reactions of olefins and dienes. Common free radical polymerization initiators include azo compounds (such as 2,2'-azobisisobutyronitrile) and organic peroxides (such as benzoyl peroxide); (2) Cationic polymerization initiators, usually Lewis acids such as AlCl 3 , BF 3 、TiCl 4 and SnCl 4 (1) Electrophilic agents such as alkali metals and their alkylates, amides, alkoxylates and hydroxides. These initiators react with monomers by providing electron pairs to generate negative ion intermediates, thereby initiating polymerization reactions. (2) Coordination polymerization catalysts, which are generally composed of two components: one is a transition metal compound (such as Ti, Zr, V, etc.) and the other is a metal alkyl compound. These catalysts form complexes with monomers through the metal center to initiate polymerization reactions. (3) Carbocationic polymerization initiators, which mainly include strong proton acids such as hydrohalic acids and sulfonic acids. Since carbocationic polymerization has high requirements for the matching between monomers and the initiation system, different types of electron-rich olefin monomers often require different types of initiators.

[0005] The selection and use of polymerization initiators should be determined according to the specific polymerization system and the performance requirements of the target product to ensure the efficient polymerization reaction and the stability and excellent performance of the final product. At present, the commonly used initiators on the market are mainly chemical initiators. Chemical initiators often cause instability during use due to some uncontrollable factors, and the qualified rate of synthetic products also varies greatly. Therefore, an initiator that can effectively improve the stability of the polymerization reaction is needed. Summary of the invention

[0006] An object of the present invention is to provide an initiator that can effectively promote the stable progress of the polymerization reaction in view of the above technical problems to be solved.

[0007] Another object of the present invention is to provide a method for preparing the initiator.

[0008] In order to achieve the above object of the invention, the present invention provides a composite initiator capable of improving the stability of a polymerization process, which comprises an oxidoreductase and an azo initiator.

[0009] Preferably, the oxidoreductase is a protease with a high catalytic effect. More preferably, the oxidoreductase is one or more of catalase, polyphenol oxidase, and peroxidase, but is not limited thereto.

[0010] Preferably, the azo initiator is a free radical initiator containing a nitrogen-nitrogen double bond in its molecular structure. More preferably, the azo initiator is one or both of azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride, but is not limited thereto.

[0011] Preferably, the mass ratio of the oxidoreductase to the azo initiator is 1:8.9.

[0012] On the other hand, the present invention also provides a method for preparing the composite initiator, the method comprising the following steps:

[0013] (1) dissolving the oxidoreductase in deionized water to prepare an enzyme solution with a mass concentration of 2.3%, and keeping it at -4°C;

[0014] (2) dissolving an azo initiator in deionized water to prepare an aqueous solution with a mass concentration of 20.5%, and keeping it at -4°C;

[0015] (3) mixing the solutions of step (1) and step (2) in a mass ratio of 1:1 and placing in an ice water bath;

[0016] (4) subjecting the mixed solution obtained in step (3) to ultrasonic treatment;

[0017] (5) The mixed solution after ultrasonic treatment is frozen at -80°C and vacuum freeze-dried to obtain a powder which is the composite initiator.

[0018] Preferably, in step (3), the power density of the ultrasonic treatment is 30 W / L to 50 W / L, more preferably 35 W / L to 45 W / W, most preferably 45 W / L.

[0019] Preferably, in step (3), the temperature of ultrasonic treatment is 36°C to 38°C, more preferably 36°C to 37°C, and most preferably 36.5°C.

[0020] Preferably, in step (3), the ultrasonic treatment time is 15 to 30 minutes, more preferably 18 to 28 minutes, and most preferably 25 minutes.

[0021] Preferably, in step (3), the dual-frequency ultrasonic working time ratio of the ultrasonic treatment is 30s:5s, the frequency is 20kHz to 50kHz, and the frequency is more preferably 30kHz.

[0022] Preferably, in step (4), the vacuum degree of vacuum freeze drying is -0.5 mPa and the drying temperature is -60°C.

[0023] The present invention combines biological perspectives, utilizes the high efficiency and stability provided by biological oxidoreductase, combines the sustained initiation effect of azo initiators, combines biological proteases with azo substances, and prepares a new type of green, efficient and stable composite initiator.

[0024] Compared with the prior art, the oxidoreductase-azo composite initiator of the present invention has a better and more stable initiation effect. In the aqueous solution polymerization system, it can stably provide free radicals. The free radicals excited by the oxidoreductase part can provide a starting temperature for the polymerization reaction, allowing the subsequent azo part to continue to initiate, thereby greatly improving the stability of the polymerization process. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention, rather than to limit the scope of the present invention.

[0026] Unless otherwise specified, the reagents, instruments and experimental operation methods used in the embodiments of the present invention are well known to those skilled in the art, and the reagents and instruments used can be purchased through commercial channels.

[0027] Example 1

[0028] The composite initiator of the present invention is prepared according to the following steps:

[0029] (1) Dissolve 11.8 g of catalase (CAS No.: 9001-05-2) in 500 g of deionized water to prepare an enzyme solution with a mass concentration of 2.3%, and keep it at -4°C for 30 minutes;

[0030] (2) dissolving 129 g of azobisisobutylimidazoline hydrochloride in 500 g of deionized water to prepare an aqueous solution with a mass concentration of 20.5%, and keeping the solution at -4°C for 30 minutes;

[0031] (3) Take 250 g of each of the above two solutions, mix them evenly, and place them in an ice water bath;

[0032] (4) The mixed solution was placed in an ultrasonic device with a set temperature of 36.5° C., with a power density of 45 W / L and ultrasonic treatment for 25 minutes. The dual-frequency ultrasonic working time ratio of the ultrasonic treatment was 30 s:5 s, and the frequency was 30 kHz.

[0033] (4) freezing the ultrasonically treated mixture at -80°C for 6 hours;

[0034] (5) placing the pre-frozen solution in a vacuum freeze dryer for vacuum freeze drying at a vacuum degree of -0.5 mPa and a freeze drying temperature of -60°C for 10 hours;

[0035] (6) Take out the freeze-dried powder, which is the oxidoreductase-azo complex initiator.

[0036] Product physical and chemical properties: light yellow powder, soluble in water.

[0037] The present invention utilizes the high efficiency and stability provided by biological oxidoreductase, combines the continuous initiation effect of azo initiators, combines biological proteases with azo substances, and prepares a new type of green, efficient and stable composite initiator, which provides a high efficiency and stable continuous initiation effect. The catalase used in the above steps can also be replaced by an equal amount of polyphenol oxidase and peroxidase, and azobisisobutylimidazoline hydrochloride can be replaced by an equal amount of azobisisobutylamidine hydrochloride, which does not significantly affect the technical effect.

[0038] Polymerization performance comparison experiment 1

[0039] The oxidoreductase-azo composite initiator prepared in Example 1 and a single azo initiator (taking azobisisobutylimidazoline hydrochloride as an example) were subjected to polymerization experiments to compare their polymerization performances.

[0040] The experimental steps are as follows:

[0041] (1) dissolving the oxidoreductase-azo composite initiator of Example 1 in water to prepare a solution with a mass concentration of 1 part per 10,000 as initiator solution A;

[0042] (2) dissolving azobisisobutylimidazoline hydrochloride in water to prepare a solution with a mass concentration of 1 / 1000 as initiator solution B;

[0043] (3) preparing 500 g of acrylamide reaction solution (the molar ratio of AM (acrylamide): DAC (dimethylaminoethyl methacrylate chloride) is 7:3, the total mass of AM and DAC accounts for 30% of the mass of the reaction system, and the pH is adjusted to 6.0), taking 0.01 g of initiator solution A and initiator solution B respectively and adding them to the reaction solution, and conducting an acrylamide polymerization experiment under the same conditions (38° C.-45° C.) for 5 hours;

[0044] (4) After the reaction is completed, an appropriate amount of terminator sodium thiosulfate is added to terminate the polymerization reaction, and then the polyacrylamide sample after the polymerization is taken out, granulated, dried, and crushed to obtain polyacrylamide dry powder.

[0045] The experiment was repeated 3 times.

[0046] The relevant performance parameters of the polyacrylamide product, such as molecular weight, ionicity, and dissolution time, were measured. The performance parameter measurement results are shown in Table 1 below.

[0047] Table 1

[0048]

[0049] In the above results, the dissolution time refers to the time taken for the polyacrylamide product formed by the polymerization reaction using an initiator to dissolve in use. The dissolution time of polyacrylamide is an important indicator for measuring its performance. Under the same molecular weight, the shorter the dissolution time, the more uniform the molecular chain is during the polymerization process, and the more stable the product performance is. As can be seen from Table 1, the dissolution time of the polyacrylamide product polymerized by the oxidoreductase-azo composite initiator of Example 1 of the present invention is shorter than the dissolution time of the polyacrylamide product polymerized by the ordinary single azobisisobutylimidazoline hydrochloride initiator. It can be seen that the oxidoreductase-azo composite initiator of Example 1 of the present invention can significantly improve the stability of the polymerization reaction used to prepare polyacrylamide, and improve the performance of the polyacrylamide product. The results show that the oxidoreductase-azo composite initiator prepared in Example 1 has a better and more stable initiation effect.

[0050] Polymerization performance experiment 2

[0051] The polymerization reaction was carried out using the oxidoreductase-azo composite initiator of Example 1, and the steps were as follows:

[0052] (1) 130 g of acrylamide monomer was added to a polymerization kettle, followed by 375 g of water, and then 1% wt of ammonium sulfate and 2.5% wt of urea (based on the mass of acrylamide monomer) were added in sequence, stirred, and the pH was adjusted to 7.80;

[0053] (2) The temperature of the reaction system was controlled at 1±0.5° C., and then nitrogen was introduced to control the nitrogen pressure to be maintained at 0.2 MPa; after 15 minutes, 1% (based on the mass of acrylamide monomer) of the oxidoreductase-azo composite initiator solution prepared in Example 1 was added with a mass concentration of 1 / 10,000, and then 0.5% (based on the mass of acrylamide monomer) of a hydrogen peroxide solution with a mass concentration of 30% was added;

[0054] (3) When the solution becomes viscous and begins to polymerize, stop nitrogen flow, insert a temperature recorder, seal the bottle, and react in the thermos bottle for 5.5 hours;

[0055] (4) When the temperature of the reaction curve reaches the highest point of 40°C, the rubber block is treated after 5 hours of heat preservation and aging, and then granulated, dried, ground and sieved to obtain white ultra-high molecular weight polyacrylamide dry powder.

[0056] The experiment was repeated 3 times.

[0057] The relevant performance parameters of the polyacrylamide product were measured, such as molecular weight, solid content, dissolution time, water-insoluble matter, etc. The results are shown in Table 2 below.

[0058] Table 2

[0059]

[0060] It can be seen from the results in Table 2 above that the dissolution time of the polymerization product of the composite initiator of Example 1 of the present invention is shorter, the stability of the polymerization reaction of polyacrylamide is higher, and the performance of the polyacrylamide product is better.

Claims

1. A composite initiator capable of improving the stability of a polymerization process, comprising an oxidoreductase and an azo initiator.

2. The composite initiator according to claim 1, characterized in that The oxidoreductase is one or more of catalase, polyphenol oxidase and peroxidase.

3. The composite initiator according to claim 1, characterized in that The azo initiator is one or both of azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride.

4. The composite initiator according to claim 1, characterized in that The mass ratio of the oxidoreductase to the azo initiator is 1:8.

9.

5. A method for preparing the composite initiator according to any one of claims 1 to 4, comprising the following steps: (1) dissolving the oxidoreductase in deionized water to prepare an enzyme solution with a mass concentration of 2.3%, and keeping it at -4°C; (2) dissolving an azo initiator in deionized water to prepare an aqueous solution with a mass concentration of 20.5%, and keeping it at -4°C; (3) mixing the solutions of step (1) and step (2) in a mass ratio of 1:1 and placing in an ice water bath; (4) subjecting the mixed solution obtained in step (3) to ultrasonic treatment; (5) The mixed solution after ultrasonic treatment is frozen at -80°C and vacuum freeze-dried to obtain a powder which is the composite initiator.

6. The method according to claim 5, characterized in that: In the step (3), the power density of the ultrasonic treatment is 30 W / L to 50 W / L.

7. The method according to claim 5, characterized in that: In the step (3), the temperature of the ultrasonic treatment is 36°C to 38°C.

8. The method according to claim 5, characterized in that: In the step (3), the ultrasonic treatment time is 15 to 30 minutes.

9. The method according to claim 5, characterized in that: In the step (3), the dual-frequency ultrasonic working time ratio of the ultrasonic treatment is 30s:5s, and the frequency is 20kHz to 50kHz.

10. The method according to claim 5, characterized in that: In the step (4), the vacuum degree of vacuum freeze drying is -0.5 mPa and the drying temperature is -60°C.

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