N-vinylpyrrolidone / 1-vinylimidazole copolymer and preparation method thereof and anti-staining agent

Abstract

The present invention provides an N-vinyl pyrrolidone / 1-vinyl imidazole copolymer and a preparation method thereof and an anti-staining agent. The method comprises the following steps: (1) mixing N-vinyl pyrrolidone, 1-vinyl imidazole, an initiator and water, and reacting to obtain a precursor material; (2) sequentially reacting the precursor material obtained in step (1) and a quaternizing agent for a first reaction and a second reaction to obtain the N-vinyl pyrrolidone / 1-vinyl imidazole copolymer. The method provided by the present invention can prepare a low molecular weight N-vinyl pyrrolidone / 1-vinyl imidazole copolymer, has the advantage of high yield, and does not require the use of toxic reagents such as mercaptoethanol.

Description

Technical Field

[0001] The invention belongs to the technical field of copolymer material preparation, and specifically relates to an N-vinyl pyrrolidone / 1-vinylimidazole copolymer and a preparation method and an anti-staining agent thereof. Background Art

[0002] Textiles need to come into contact with various equipment, processing water, dyeing and chemical auxiliaries, etc. in various processing procedures after weaving, and will be stained and colored, collectively referred to as staining, which is a common problem in the textile processing process. The anti-staining technology of textiles is one of the important measures to ensure product quality, improve product grade and form product pre-design style.

[0003] In recent years, researchers have used anti-fouling agents to prevent unfixed dyes, hydrolyzed dyes, printing pastes and other auxiliaries washed off fabrics from reattaching to fabrics or yarns. Anti-fouling agents are generally composed of anionic surfactants, nonionic surfactants and multifunctional chelating dispersants, anti-redeposition agents, builders, thickeners, etc. They not only have the ability of penetration, emulsification, dispersion, decontamination and cleaning, but also have an adsorption effect on dirt, a strong affinity for re-stained dyes, and a migration effect.

[0004] At present, there is a related literature report that N-vinyl pyrrolidone / 1-vinyl imidazole copolymer (abbreviated as VP / VI copolymer) can be used as an anti-staining agent in the washing process of textile printing and dyeing, and when used as an anti-staining agent, the anti-staining effect of VP / VI copolymer with low molecular weight is better. CA2156502A1 discloses a synthetic method of VP / VI copolymer, wherein the method needs to use a sulfur-containing chain transfer agent (such as mercaptoethanol), but the toxicity of the above-mentioned chain transfer agent is relatively large, and has a heavier pungent odor, which is not conducive to large-scale production. In addition, the molecular weight of the VP / VI copolymer obtained by the existing preparation method in the prior art is generally higher.

[0005] Therefore, in the art, there is an urgent need to develop a method for preparing a low molecular weight VP / VI copolymer, wherein the prepared VP / VI copolymer has a good anti-staining effect. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide an N-vinyl pyrrolidone / 1-vinylimidazole copolymer and a preparation method thereof and an anti-staining agent. The method provided by the present invention can prepare a low molecular weight N-vinyl pyrrolidone / 1-vinylimidazole copolymer, has the advantage of high yield, and does not require the use of toxic reagents such as mercaptoethanol.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing an N-vinyl pyrrolidone / 1-vinylimidazole copolymer, the method comprising the following steps:

[0009] (1) mixing N-vinyl pyrrolidone, 1-vinylimidazole, an initiator and water, and reacting to obtain a precursor material;

[0010] (2) The precursor material obtained in step (1) and the quaternizing agent are subjected to a first reaction and a second reaction in sequence to obtain the N-vinylpyrrolidone / 1-vinylimidazole copolymer.

[0011] The invention uses water as a reaction medium for the copolymerization reaction of N-vinyl pyrrolidone / 1-vinylimidazole, thereby accelerating the polymerization rate of monomers, and uses an initiator to initiate the polymerization of N-vinyl pyrrolidone and 1-vinylimidazole, thereby preparing a low-molecular-weight N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a high yield. In addition, the invention performs quaternization treatment on a precursor material so that the precursor material has a positive charge, thereby being able to firmly adsorb dyes, and facilitating the improvement of the anti-staining effect of the N-vinyl pyrrolidone / 1-vinylimidazole copolymer.

[0012] Preferably, the N-vinyl pyrrolidone in step (1) is obtained by purification.

[0013] Preferably, based on the total mass of N-vinylpyrrolidone, 1-vinylimidazole and water as 100%, the mass percentage of N-vinylpyrrolidone in step (1) is 10%-60%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.

[0014] Preferably, based on the total mass of N-vinylpyrrolidone, 1-vinylimidazole and water as 100%, the mass percentage of 1-vinylimidazole in step (1) is 10%-50%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc.

[0015] Preferably, based on the total mass of N-vinylpyrrolidone, 1-vinylimidazole and water as 100%, the mass percentage of water in step (1) is 10%-80%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0016] Preferably, the initiator in step (1) comprises a first initiator and a second initiator.

[0017] Preferably, the order of adding the first initiator and the second initiator is to first add the first initiator and stir it, and then add the second initiator.

[0018] In the present invention, N-vinyl pyrrolidone and 1-vinylimidazole are firstly treated with a first initiator; secondly, polymerization is initiated with a second initiator, which is beneficial for large-scale preparation of low molecular weight N-vinyl pyrrolidone / 1-vinylimidazole copolymers with a higher yield.

[0019] Preferably, the first initiator comprises a peroxide-based initiator.

[0020] Preferably, the peroxide initiator includes any one of tert-butyl hydroperoxide, tert-amyl hydroperoxide, hydrogen peroxide, ammonium persulfate or potassium persulfate, or a combination of at least two thereof.

[0021] In the present invention, the selection of peroxide initiators can adjust the molecular weight of the VP / VI copolymer and improve the anti-staining performance of the VP / VI copolymer.

[0022] Preferably, the second initiator comprises an azo compound initiator.

[0023] Preferably, the azo compound initiator includes any one of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile or azobisisobutyrate, or a combination of at least two thereof.

[0024] In the present invention, the azo compound initiator is selected because of its advantages of low initiation temperature, high initiation efficiency and high monomer conversion rate.

[0025] Preferably, based on the total mass of N-vinylpyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the initiator in step (1) is 2-6%, for example, 2%, 3%, 4%, 5%, 6%, etc.

[0026] Preferably, based on the total mass of the N-vinylpyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the first initiator is 0.1-1.5%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, etc.

[0027] In the present invention, by regulating the mass percentage of the first initiator, the active free radicals in the polymerization system can be controlled at an appropriate concentration, thereby controlling the molecular weight of the VP / VI polymer. If the content is too low, the molecular weight of the VP / VI copolymer will be higher, and vice versa, the polymerization reaction conversion rate will be lower.

[0028] Preferably, based on the total mass of the N-vinylpyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the second initiator is 1.9-3.8%, for example, it can be 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8% and the like.

[0029] In the present invention, by regulating the mass percentage of the second initiator, the monomer free radicals in the system have better activity, ensuring a smooth and sufficient reaction process; too low a content will lead to a slower reaction rate and a higher molecular weight; otherwise, the reaction rate will be too fast to be controlled and the cross-linking by-products will be higher.

[0030] Preferably, the mixing in step (1) is carried out with stirring in an inert atmosphere.

[0031] Preferably, the inert atmosphere comprises argon and / or nitrogen.

[0032] Preferably, the mixing temperature in step (1) is 55-80°C, for example, it can be 55°C, 58°C, 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 77°C, 80°C, etc.

[0033] Preferably, the reaction temperature in step (1) is 55-80°C, for example, it can be 55°C, 58°C, 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 77°C, 80°C, etc.; the reaction time is 4-8h, for example, it can be 4h, 5h, 6h, 7h, 8h, etc.

[0034] Preferably, the quaternizing agent in step (2) comprises any one or a combination of at least two of benzyl chloride, benzyl chloride, triethylammonium chloride, dimethyl sulfate, diethyl sulfate or dimethyl carbonate.

[0035] Preferably, based on the total mass of N-vinylpyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the quaternary ammonium agent in step (2) is 2.5-7.5%, for example, it can be 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, etc.

[0036] In the present invention, by adjusting the mass percentage of the quaternary ammonium agent, the VP / VI polymer has a stronger ionic property. If the content is too low, the ionization degree of the polymer is low and the adsorption capacity for dye particles is weak. Otherwise, the effective anchoring groups in the polymer will be reduced, the dispersion performance will be reduced, and its soaping separation effect will be affected.

[0037] Preferably, the temperature of the first reaction in step (2) is 45-50°C, for example, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, etc.; the time is 2-4h, for example, 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0038] Preferably, the temperature of the second reaction in step (2) is 60-85°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, etc.; the time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h, 3h, etc.

[0039] Preferably, the second reaction in step (2) further comprises cooling the reaction solution.

[0040] Preferably, the cooling treatment temperature is room temperature.

[0041] In a second aspect, the present invention provides an N-vinyl pyrrolidone / 1-vinylimidazole copolymer, wherein the N-vinyl pyrrolidone / 1-vinylimidazole copolymer is prepared by the method for preparing the N-vinyl pyrrolidone / 1-vinylimidazole copolymer according to the first aspect.

[0042] Preferably, the weight average molecular weight of the N-vinylpyrrolidone / 1-vinylimidazole copolymer is 2000-40000, for example, 2000, 5000, 7000, 10000, 12000, 15000, 20000, 22000, 25000, 30000, 33000, 35000, 37000, 40000, etc.

[0043] In a third aspect, the present invention provides an anti-staining agent, comprising the N-vinyl pyrrolidone / 1-vinylimidazole copolymer according to the second aspect.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The invention provides a method for preparing an N-vinyl pyrrolidone / 1-vinylimidazole copolymer. The method uses water as a reaction medium for the N-vinyl pyrrolidone / 1-vinylimidazole copolymerization reaction, thereby accelerating the polymerization rate of monomers, and uses an initiator to initiate polymerization of N-vinyl pyrrolidone and 1-vinylimidazole, thereby preparing a low-molecular-weight N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a high yield. In addition, the method performs quaternization treatment on a precursor material so that the precursor material has a positive charge, thereby being able to firmly adsorb dyes, thereby facilitating improving the anti-staining effect of the N-vinyl pyrrolidone / 1-vinylimidazole copolymer. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] Example 1

[0048] This embodiment provides an N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a weight average molecular weight of 38,000 and a preparation method thereof, the method comprising the following steps:

[0049] (1) In a nitrogen atmosphere, based on the total mass of N-vinyl pyrrolidone, 1-vinylimidazole and deionized water as 100%, 40% of purified N-vinyl pyrrolidone, 40% of 1-vinylimidazole and 20% of deionized water are stirred, heated to 65° C., tert-butyl hydroperoxide initiator (the mass percentage of tert-butyl hydroperoxide initiator is 1% based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%) is added and stirred for 30 minutes, and then azobisisobutyronitrile initiator (the mass percentage of azobisisobutyronitrile initiator is 2.3% based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%) is added and stirred, and the polymerization is continued for 4.5 hours to obtain a precursor material;

[0050] (2) The precursor material obtained in step (1) and dimethyl sulfate (the mass percentage of dimethyl sulfate is 6.5%, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%) are reacted at 48° C. for 3 h and at 75° C. for 2 h, respectively, and cooled to room temperature to obtain the N-vinyl pyrrolidone / 1-vinylimidazole copolymer.

[0051] Example 2

[0052] This embodiment provides an N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a weight average molecular weight of 4000 and a preparation method thereof, the method comprising the following steps:

[0053] (1) In a nitrogen atmosphere, based on the total mass of N-vinyl pyrrolidone, 1-vinylimidazole and deionized water as 100%, 18% of purified N-vinyl pyrrolidone, 12% of 1-vinylimidazole and 70% of deionized water are stirred, heated to 75° C., potassium persulfate initiator (based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of potassium persulfate initiator is 0.8%), stirred for 30 minutes, and then azobisisoheptanitrile initiator (based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of azobisisoheptanitrile initiator is 2.1%), stirred, and the polymerization is continued for 6.5 hours to obtain a precursor material;

[0054] (2) The precursor material obtained in step (1) and triethylammonium trichloride (the mass percentage of triethylammonium trichloride is 5%, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%) are reacted at 45° C. for 2.5 h and at 65° C. for 2 h, respectively, and cooled to room temperature to obtain the N-vinyl pyrrolidone / 1-vinylimidazole copolymer.

[0055] Example 3

[0056] This embodiment provides an N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a weight average molecular weight of 26000 and a preparation method thereof, the method comprising the following steps:

[0057] (1) In a nitrogen atmosphere, based on the total mass of N-vinyl pyrrolidone, 1-vinylimidazole and deionized water as 100%, 20% of purified N-vinyl pyrrolidone, 28% of 1-vinylimidazole and 52% of deionized water are stirred, heated to 60°C, and then a tert-amyl hydroperoxide initiator (based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the tert-amyl hydroperoxide initiator is 1.2%) is added and stirred for 30 minutes, and then azobisisovaleronitrile initiator (based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the azobisisovaleronitrile initiator is 2.5%) is added and stirred, and the polymerization is continued for 3.5 hours to obtain a precursor material;

[0058] (2) The precursor material obtained in step (1) and benzyl chloride (the mass percentage of benzyl chloride is 6%, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%) are reacted at 45° C. for 2.5 h and at 65° C. for 3 h, respectively, and cooled to room temperature to obtain the N-vinyl pyrrolidone / 1-vinylimidazole copolymer.

[0059] Example 4

[0060] This embodiment provides an N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a weight average molecular weight of 40,000 and a preparation method thereof, the method comprising the following steps:

[0061] (1) In a nitrogen atmosphere, based on the total mass of N-vinyl pyrrolidone, 1-vinylimidazole and deionized water as 100%, 60% of purified N-vinyl pyrrolidone, 10% of 1-vinylimidazole and 30% of deionized water are stirred, heated to 80°C, tert-butyl hydroperoxide initiator (the mass percentage of tert-butyl hydroperoxide initiator is 0.5% based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%) is added and stirred for 30 minutes, and then azobisisoheptanonitrile initiator (the mass percentage of azobisisoheptanonitrile initiator is 1.9% based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%) is added and stirred, and the polymerization is continued for 8 hours to obtain a precursor material;

[0062] (2) The precursor material obtained in step (1) and dimethyl sulfate (the mass percentage of dimethyl sulfate is 7.5%, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%) are reacted at 50° C. for 4 h and at 85° C. for 1 h, respectively, and cooled to room temperature to obtain the N-vinyl pyrrolidone / 1-vinylimidazole copolymer.

[0063] Example 5

[0064] This embodiment provides an N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a weight average molecular weight of 2000 and a preparation method thereof, the method comprising the following steps:

[0065] (1) In a nitrogen atmosphere, based on the total mass of N-vinyl pyrrolidone, 1-vinylimidazole and deionized water as 100%, 10% of purified N-vinyl pyrrolidone, 50% of 1-vinylimidazole and 40% of deionized water are stirred, heated to 70°C, and then a hydrogen peroxide initiator (based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of hydrogen peroxide initiator is 1.5%) is added and stirred for 30 minutes, and then azobisisoheptanitrile initiator (based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of azobisisoheptanitrile initiator is 3.8%) is added and stirred, and the polymerization is continued for 4 hours to obtain a precursor material;

[0066] (2) The precursor material obtained in step (1) and diethyl sulfate (the mass percentage of diethyl sulfate is 2.5%, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%) are reacted at 45° C. for 2 h and at 60° C. for 1 h, respectively, and cooled to room temperature to obtain the N-vinyl pyrrolidone / 1-vinylimidazole copolymer.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1 is that, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%, the mass percentage content of tert-butyl hydroperoxide initiator in step (1) is 0.05%, and the rest is the same as embodiment 1.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 1 is that, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%, the mass percentage content of the tert-butyl hydroperoxide initiator in step (1) is 2%, and the rest is the same as embodiment 1.

[0071] Example 8

[0072] The difference between this embodiment and embodiment 1 is that, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%, the mass percentage content of azobisisobutyronitrile initiator in step (1) is 1%, and the rest is the same as embodiment 1.

[0073] Example 9

[0074] The difference between this embodiment and embodiment 1 is that, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%, the mass percentage of azobisisobutyronitrile initiator in step (1) is 4.5%, and the rest is the same as embodiment 1.

[0075] Example 10

[0076] The difference between this embodiment and embodiment 1 is that, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%, the mass percentage of dimethyl sulfate in step (2) is 1.5%, and the rest is the same as embodiment 1.

[0077] Embodiment 11

[0078] The difference between this embodiment and embodiment 1 is that, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%, the mass percentage of dimethyl sulfate in step (2) is 8.5%, and the rest is the same as embodiment 1.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 1 is that in step (1), no tert-butyl hydroperoxide initiator is added, and only azobisisobutyronitrile initiator is added (based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of azobisisobutyronitrile initiator is 3.3%), and the rest is the same as Example 1.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 1 is that in step (1), 40% of purified N-vinyl pyrrolidone, 40% of 1-vinylimidazole and 20% of deionized water are stirred, heated to 65°C, and then azobisisobutyronitrile initiator (the mass percentage of azobisisobutyronitrile initiator is 1%, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%) is added and stirred for 30 minutes, and then tert-butyl hydroperoxide initiator (the mass percentage of tert-butyl hydroperoxide initiator is 2.3%, based on the total mass of N-vinyl pyrrolidone and 1-vinylimidazole being 100%) is added and stirred, and the polymerization is continued for 4.5 hours to obtain a precursor material. The rest is the same as Example 1.

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 1 is that step (2) is not performed, and only step (1) is performed, and the rest is the same as Example 1.

[0085] Test conditions

[0086] The N-vinyl pyrrolidone / 1-vinylimidazole copolymers provided in Examples 1 to 11 and Comparative Examples 1 to 3 were tested for anti-staining effect, and the test method was as follows:

[0087] After the bleached cotton fabric is dyed and washed according to the following conditions, the K / S value of the stained fabric is measured using a colorimeter. The specific conditions are as follows:

[0088] Dyeing: bleached cotton, reactive turquoise blue BES 4% (owf), bath ratio 1:40, 90°C, 15min.

[0089] Washing: anti-staining agent 2.0g / L (based on dry product), bath ratio 1:40, hot water washing: 60℃, 10min, tap water washing 5min, drying in 80℃ air drying oven.

[0090] The test results are shown in Table 1:

[0091] Table 1

[0092]

[0093]

[0094] As can be seen from Table 1, the N-vinyl pyrrolidone / 1-vinylimidazole copolymer prepared by the present invention has a relatively low molecular weight, and the precursor material is quaternized to make it positively charged, so that it can firmly adsorb dyes, which is beneficial to improving the anti-staining effect of the N-vinyl pyrrolidone / 1-vinylimidazole copolymer. The present invention controls the active free radicals in the polymerization system to a certain suitable concentration by regulating the mass percentage of the first initiator, thereby controlling the molecular weight of the N-vinyl pyrrolidone / 1-vinylimidazole copolymer. At the same time, the present invention controls the mass percentage of the second initiator so that the monomer free radicals in the system have better activity, ensuring a stable and sufficient reaction process.

[0095] In addition, the present invention firstly uses a first initiator to pre-treat N-vinyl pyrrolidone and 1-vinylimidazole; secondly, a second initiator is used to initiate polymerization, which is conducive to large-scale preparation of low molecular weight N-vinyl pyrrolidone / 1-vinylimidazole copolymers with a higher yield.

[0096] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an N-vinyl pyrrolidone / 1-vinylimidazole copolymer having a weight average molecular weight of 4000-26000, It is characterized in that The method comprises the following steps: (1) mixing N-vinyl pyrrolidone, 1-vinylimidazole, an initiator and water, and reacting to obtain a precursor material; (2) subjecting the precursor material obtained in step (1) and the quaternizing agent to a first reaction and a second reaction in sequence to obtain the N-vinylpyrrolidone / 1-vinylimidazole copolymer; The initiator in step (1) consists of a first initiator and a second initiator; The order of adding the first initiator and the second initiator is to first add the first initiator and stir it, and then add the second initiator; The first initiator is a peroxide initiator; The peroxide initiator includes any one of tert-butyl hydroperoxide, tert-amyl hydroperoxide, ammonium persulfate or potassium persulfate, or a combination of at least two thereof; The second initiator is an azo compound initiator; Based on the total mass of the N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the first initiator is 0.8-1.5%; Based on the total mass of the N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the second initiator is 1.9-3.8%; The quaternizing agent in step (2) is any one or a combination of at least two of benzyl chloride, benzyl chloride, triethylammonium chloride, dimethyl sulfate, diethyl sulfate or dimethyl carbonate; Based on the total mass of the N-vinyl pyrrolidone and 1-vinylimidazole as 100%, the mass percentage of the quaternary ammonium agent in step (2) is 2.5-7.5%.

2. The method according to claim 1, It is characterized in that The N-vinyl pyrrolidone in step (1) is obtained through purification.

3. The method according to claim 1, It is characterized in that Based on the total mass of the N-vinyl pyrrolidone, 1-vinylimidazole and water as 100%, the mass percentage of the N-vinyl pyrrolidone in step (1) is 10%-60%.

4. The method according to claim 1, It is characterized in that Based on the total mass of the N-vinyl pyrrolidone, 1-vinylimidazole and water as 100%, the mass percentage of the 1-vinylimidazole in step (1) is 10%-50%.

5. The method according to claim 1, It is characterized in that Based on the total mass of the N-vinyl pyrrolidone, 1-vinylimidazole and water as 100%, the mass percentage of the water in step (1) is 10%-80%.

6. The method according to claim 1, It is characterized in that The azo compound initiator includes any one of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile or azobisisobutyrate, or a combination of at least two thereof.

7. The method according to claim 1, It is characterized in that The mixing in step (1) is carried out with stirring in an inert atmosphere.

8. The method according to claim 7, It is characterized in that The inert atmosphere includes argon and / or nitrogen.

9. The method according to claim 1, It is characterized in that The mixing temperature in step (1) is 55-80°C.

10. The method according to claim 1, It is characterized in that The reaction temperature in step (1) is 55-80°C and the reaction time is 4-8h.

11. The method according to claim 1, It is characterized in that The temperature of the first reaction in step (2) is 45-50° C. and the time is 2-4 hours.

12. The method according to claim 1, It is characterized in that The temperature of the second reaction in step (2) is 60-85° C. and the time is 1-3 h.

13. The method according to claim 1, It is characterized in that The second reaction in step (2) further includes cooling the reaction solution.

14. The method according to claim 13, It is characterized in that The temperature of the cooling treatment is room temperature.

15. An N-vinylpyrrolidone / 1-vinylimidazole copolymer, It is characterized in that The N-vinyl pyrrolidone / 1-vinylimidazole copolymer is prepared by the method for preparing an N-vinyl pyrrolidone / 1-vinylimidazole copolymer with a weight average molecular weight of 4000-26000 according to any one of claims 1-14, and the weight average molecular weight of the N-vinyl pyrrolidone / 1-vinylimidazole copolymer is 4000-26000. 16.An anti-staining agent, It is characterized in that The anti-staining agent comprises the N-vinyl pyrrolidone / 1-vinylimidazole copolymer according to claim 15.

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