Caprolactam copolymer quaternization method and quaternized caprolactam copolymer

Abstract

The invention relates to the field of high polymer materials, and discloses a caprolactam copolymer quaternization method and a quaternized caprolactam copolymer. The method comprises the following steps: under a solvent-free condition, a caprolactam copolymer and a quaternization reagent are subjected to a quaternization reaction to obtain a quaternized caprolactam copolymer, the temperature of the quaternization reaction is Tm-40 DEG C to Tm + 40 DEG C, and Tm is the melting point of the caprolactam copolymer. According to the method, quaternization reaction can be carried out under the solvent-free condition, quaternization efficiency is high, large-scale production is easy, and the obtained quaternized caprolactam copolymer has better antibacterial performance.

Description

Technical Field

[0001] This invention relates to the technical field of polymer materials, specifically to a method for quaternizing caprolactam copolymers and quaternized caprolactam copolymers. Background Technology

[0002] Caprolactam polymer (commonly known as nylon 6) possesses excellent properties such as light weight, high strength, wear resistance, and resistance to weak acids, weak alkalis, and some organic solvents, making it widely used in fibers, engineering plastics, and films. However, nylon 6 contains highly polar amide groups in its molecular chain, which readily form hydrogen bonds with water molecules, causing the product to easily absorb moisture from the environment. Furthermore, nylon 6 has high crystallinity, low melt strength, and poor flowability, requiring more stringent processability.

[0003] Copolymerization of caprolactam and functionalized monomers is an effective means to improve the properties of caprolactam polymers and expand their application areas. Deniz Tunc (Mcromolecules, 2014, 47: 8247-8254) prepared a reversible photosensitizing nylon copolymer by introducing a cinnamoyl group onto the α-amino group of α-amino-ε-caprolactam to obtain a functionalized comonomer, which was then anionicly copolymerized with caprolactam. However, since the formation of the α-position N-anion can terminate polymerization or easily lead to gelation, the comonomer content is limited to no more than 5%.

[0004] Quaternization involves reacting a quaternizing reagent with a tertiary amine in the branched chain of caprolactam to obtain a quaternized caprolactam copolymer. CN115707727A describes the preparation of a copolymer of functionalized aminocaprolactam and caprolactam using anionic polymerization. This copolymer, dissolved in a solvent, undergoes a quaternization reaction with a haloalkane to obtain a quaternized caprolactam copolymer with antibacterial properties. However, this method requires a large amount of solvent, has poor quaternization efficiency, and is difficult to industrialize. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high solvent consumption and poor quaternization efficiency in existing caprolactam copolymer quaternization methods, and to provide a method for quaternizing caprolactam copolymers and a quaternized caprolactam copolymer. The method of this invention enables quaternization under solvent-free conditions, achieves high quaternization efficiency, and yields a quaternized caprolactam copolymer with better antibacterial properties.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for quaternizing caprolactam copolymers, wherein the method comprises:

[0007] Under solvent-free conditions, caprolactam copolymer and quaternizing agent are subjected to quaternization reaction to obtain quaternized caprolactam copolymer. The temperature of the quaternization reaction is from Tm-40℃ to Tm+40℃, where Tm is the melting point of caprolactam copolymer.

[0008] Preferably, the temperature of the quaternization reaction is from Tm-30℃ to Tm-10℃.

[0009] A second aspect of the present invention provides a quaternized caprolactam copolymer obtained by the method described in the first aspect.

[0010] Through the above technical solution, the present invention provides a method for quaternizing caprolactam copolymers. This method can carry out the quaternization reaction under solvent-free conditions, has high quaternization efficiency, is easy to scale up production, and the obtained quaternized caprolactam copolymer has better antibacterial properties. Attached Figure Description

[0011] Figure 1 This is the NMR spectrum of the quaternized caprolactam copolymer from Example 1. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] The first aspect of this invention provides a method for quaternizing caprolactam copolymers, wherein the method includes:

[0014] Under solvent-free conditions, caprolactam copolymer and quaternizing agent are subjected to quaternization reaction to obtain quaternized caprolactam copolymer. The temperature of the quaternization reaction is from Tm-40℃ to Tm+40℃, where Tm is the melting point of caprolactam copolymer.

[0015] In this invention, by setting the temperature of the quaternization reaction to Tm-40℃ to Tm+40℃, the quaternization reaction can be carried out under solvent-free conditions, which can solve the problem of large solvent consumption caused by the need for solvent reaction in the prior art. Moreover, the quaternization method of this invention has high quaternization efficiency, is easy to scale up production, and the obtained quaternized caprolactam copolymer has better antibacterial properties.

[0016] In some specific embodiments of the present invention, the caprolactam copolymer is a caprolactam copolymer containing tertiary amine branches, preferably a copolymer having the structure of formula (I).

[0017] Among them, R1 and R2 are each independently selected from C. 1-24 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-12 Alicyclic hydrocarbon group, substituted or unsubstituted C 6-18 Aryl and C 7-30 Alkyl aryl, or R1 and R2 groups on the same nitrogen atom together with the attached N atom to form a 5-7 member saturated or unsaturated heterocycle, where x and y represent the molar content of the copolymer units in their respective brackets, where x is selected from 0.01-0.3 and y is selected from 0.7-0.99, and x+y=1.

[0018] In some specific embodiments of the present invention, preferably, the R1 and R2 groups are each independently selected from C 1-12 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-6 Alicyclic hydrocarbon group, substituted or unsubstituted C 7-16 The aryl group, or R1 and R2 together with the attached N atom, form a 5-6 member saturated or unsaturated heterocycle; more preferably, the R1 and R2 groups are each independently selected from methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, allyl, phenyl or benzyl, or R1 and R2 together with the attached N atom form a tetrahydropyrrole or hexahydropyridyl.

[0019] In some specific embodiments of the present invention, the quaternizing agent has the structure shown in formula (II) or formula (III):

[0020] R3-Hal(II),

[0021] Hal-R4-Hal(III),

[0022] Among them, the R3 group is selected from hydrogen, C 1-24 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-12 Alicyclic hydrocarbon group, substituted or unsubstituted C 6-18 Aryl or C 7-30 Alkyl aryl; preferably, the R3 group is selected from hydrogen, C 1-12 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-6 Alicyclic hydrocarbon group, substituted or unsubstituted C 7-16 Aryl; more preferably, the R3 group is selected from hydrogen, methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, phenyl or benzyl.

[0023] In some specific embodiments of the present invention, the R4 group is selected from C 1-24 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-12Alicyclic alkylene groups, substituted or unsubstituted C 6-18 aryl or C 7-30 Alkyl arylene; preferably, the R4 group is selected from hydrogen, C 1-12 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-6 Alicyclic hydrocarbon group, substituted or unsubstituted C 7-16 Aryl; more preferably, the R4 group is selected from hydrogen, methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, phenyl or benzyl.

[0024] In some specific embodiments of the present invention, Hal represents a halogen, which may be one or more of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0025] In some specific embodiments of the present invention, the quaternization reaction time is 1-12 hours, preferably 3-6 hours. The present invention achieves a shorter quaternization reaction time and higher quaternization reaction efficiency through a solvent-free quaternization reaction.

[0026] In some specific embodiments of the present invention, preferably, the temperature of the quaternization reaction is from Tm-30℃ to Tm-10℃. Within the preferred temperature range of the quaternization reaction of the present invention, the quaternization method can achieve high quaternization efficiency, and the obtained quaternized caprolactam copolymer has better antibacterial properties.

[0027] In some specific embodiments of the present invention, the molar ratio of the caprolactam copolymer to the quaternizing agent is 1:1-20, preferably 1:1.1-10. Within the preferred molar ratio range of the caprolactam copolymer and the quaternizing agent of the present invention, the quaternization method can achieve high quaternization efficiency, and the obtained quaternized caprolactam copolymer has better antibacterial properties.

[0028] In some specific embodiments of the present invention, the method further includes: extracting and filtering the mixture after the quaternization reaction, and drying the resulting filter cake to obtain the quaternized caprolactam copolymer.

[0029] In some specific embodiments of the present invention, the extractant used for extraction is selected from fatty alcohols, preferably from C1-C4 fatty alcohols; further selected from methanol and / or ethanol.

[0030] The present invention does not have a particular limitation on the amount of the extractant, which is well known to those skilled in the art; the purpose is simply to achieve the extraction and separation of the quaternized caprolactam copolymer.

[0031] In some specific embodiments of the present invention, the extraction temperature is 25-60°C and the extraction time is 10-15 hours.

[0032] In some specific embodiments of the present invention, the filtrate obtained by filtration is separated to obtain unreacted quaternizing reagent and extractant, which are then reused. The separation method preferably includes: vacuum rotary evaporating the filtrate at 40-60°C; the solution obtained after condensing the evaporated gas is the extractant, and the remaining liquid after rotary evaporation is the quaternizing reagent. Through the quaternization reaction of the present invention, no solvent is required, the filtrate does not contain solvents or other substances that need to be separated, and there are fewer impurities. Unreacted quaternizing reagent and extractant can be directly separated and reused. The quaternization reaction method of the present invention is simpler and more efficient.

[0033] A second aspect of the present invention provides a quaternized caprolactam copolymer obtained by the method described in the first aspect.

[0034] According to a particularly preferred embodiment of the present invention, a method for quaternizing caprolactam copolymers, wherein the method comprises:

[0035] (1) Under solvent-free conditions, the caprolactam copolymer and the quaternizing agent are subjected to a quaternization reaction to obtain a quaternized caprolactam copolymer. The temperature of the quaternization reaction is Tm-30℃ to Tm-10℃, where Tm is the melting point of the caprolactam copolymer. The molar ratio of the caprolactam copolymer to the quaternizing agent is 1:1.1-10, and the quaternization reaction time is 3-6h.

[0036] (2) The mixture after the quaternization reaction is extracted and filtered, and the resulting filter cake is dried to obtain the quaternized caprolactam copolymer; the extraction temperature is 25-60℃, and the extraction time is 10-15h. The filtrate obtained by filtration is separated to obtain unreacted quaternization reagent and extractant, which are reused respectively.

[0037] The present invention will be described in detail below through embodiments.

[0038] Test methods for the properties of the obtained quaternized caprolactam polymer:

[0039] (1) Structure of quaternized caprolactam copolymer

[0040] In this invention, the structures of the quaternized caprolactam copolymer and the caprolactam copolymer are determined by nuclear magnetic resonance (NMR), specifically using a Burker AV-300 liquid superconducting NMR spectrometer, deuterated trifluoroacetic acid solvent, and at room temperature.

[0041] (2) Melting point

[0042] The melting points of the obtained caprolactam copolymer and quaternized caprolactam copolymer were determined using a differential scanning calorimeter (DSC3) from Mettler Toledo. The specific method is as follows: (1) Weigh 5 mg of the sample and place it in the sample cell of the DSC3 differential scanning calorimeter. In a nitrogen flow of 50 ml / min, heat the sample from 25 °C to 250 °C at a heating rate of 10 °C / min and hold the temperature for 5 min; (2) Then lower the temperature to 25 °C at a rate of 10 °C / min; (3) Then heat the sample to 250 °C at a rate of 10 °C / min and test the melting point.

[0043] (3) Antibacterial properties

[0044] The quaternized caprolactam copolymers prepared in the above examples and comparative examples were pressed into 0.75cm × 0.75cm square sheets, sterilized by irradiation under a UV lamp for 30 min, and then the prepared bacterial solution was dropped onto the sheets. After covering with a PE film, the sheets were incubated at 37°C for 6 h. After sonication for 3 min, the solution was diluted 100 times and placed on a solid culture medium, incubated at 37°C for 20 h. Nylon 6 homopolymer (intrinsic viscosity 2.8) served as the control group. The bacteria used for testing were Staphylococcus aureus (S aureus) ATCC6538 and Escherichia coli (E coli) ATCC25922. The antibacterial rate was calculated using the following formula:

[0045]

[0046] Method for determining quaternization rate: The determination is based on the NMR spectrum of the quaternized caprolactam copolymer, as shown in Figure 1: Quaternization rate = area of ​​peak b / (area of ​​peak a + area of ​​peak b).

[0047] Peak b represents the H on the carbon bonded to the tertiary amine after the quaternization reaction, while peak a represents the H on the carbon bonded to the dimethylamino group (i.e., without quaternization) after the quaternization reaction.

[0048] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0049] Preparation Example 1

[0050] The dimethyl-substituted aminocaprolactam was prepared according to the method in Example 1 of CN115707727A.

[0051] Preparation Example 2

[0052] Preparation of dimethyl-amino-caprolactam / caprolactam copolymer: 3.4 g of dimethyl-amino-caprolactam, 20 g of caprolactam, and 2 g of water were added to a 50 mL high-pressure reactor. The reaction system was purged with nitrogen at room temperature, and ring-opening polymerization was carried out under a nitrogen atmosphere. The stirring speed was 120 rpm, and the reaction was maintained at 180 °C and 1.1 MPa for 3 h (aqueous phase ring-opening stage). Then, the temperature was increased to 220 °C and 1.8 MPa and maintained for 2 h (high-pressure polymerization stage). Afterward, the pressure was reduced to 0.7 MPa and 200 °C, and the reaction was continued for 1 h (low-pressure polymerization stage). An intermediate product with the structure shown in formula (IV) was obtained, with a yield of 91%, x = 0.09, y = 0.91, and a melting point of 203 °C.

[0053]

[0054] Preparation Example 3

[0055] Preparation of dimethyl-amino-caprolactam / caprolactam copolymer: 5.6 g of dimethyl-amino-caprolactam, 20 g of caprolactam, and 2 g of water were added to a 50 mL high-pressure reactor. The reaction system was purged with nitrogen at room temperature, and ring-opening polymerization was carried out under a nitrogen atmosphere. The stirring speed was 120 rpm, and the reaction was maintained at 180 °C and 1.1 MPa for 3 h (aqueous phase ring-opening stage). Then, the temperature was increased to 220 °C and 1.8 MPa and maintained for 2 h (high-pressure polymerization stage). Afterward, the pressure was reduced to 0.7 MPa and 200 °C, and the reaction was continued for 1 h (low-pressure polymerization stage). An intermediate product with the structure shown in formula (V) was obtained, with a yield of 91%, x = 0.15, y = 0.85, and a melting point of 196 °C.

[0056]

[0057] Example 1

[0058] 10 g (0.084 mol) of the dimethylaminocaprolactam / caprolactam copolymer obtained in Preparation Example 2 and 30 g (0.136 mol) of bromodecane were added to a 50 mL reaction vessel. The vessel was evacuated and purged with nitrogen four times. The reaction was carried out for 6 h at 180 °C and 0.3 MPa under a nitrogen atmosphere. The reaction product was transferred to a 1 L extraction vessel at 60 °C and extracted with 100 mL of ethanol for 12 h. The mixture was then filtered, and the filter cake was dried to obtain the quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 95%. Quaternization was confirmed by NMR spectroscopy. Figure 1 As shown, its quaternization rate = peak area b / (peak area b + peak area a), and the melting point of the quaternization product is 170℃.

[0059] Example 2

[0060] 10 g (0.084 mol) of the dimethylaminocaprolactam / caprolactam copolymer obtained in Preparation Example 2 and 30 g (0.155 mol) of octane bromide were added to a 50 mL reaction vessel, and the mixture was evacuated and purged with nitrogen four times. The reaction was carried out for 3 h at 190 °C and 0.3 MPa under a nitrogen atmosphere. The reaction product was transferred to a 1 L extraction vessel at 40 °C and extracted with 100 mL of methanol for 15 h. The mixture was then filtered, and the filter cake was dried to obtain the quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 92% and a melting point of 160 °C.

[0061] Example 3

[0062] 10 g (0.084 mol) of the dimethylaminocaprolactam / caprolactam copolymer obtained in Preparation Example 2 and 30 g (0.182 mol) of hexane were added to a 50 mL reaction vessel, and the mixture was evacuated and purged with nitrogen four times. The reaction was carried out for 6 h at 180 °C and 0.25 MPa under a nitrogen atmosphere. The reaction product was transferred to a 1 L extraction vessel at 60 °C and extracted with 100 mL of ethanol for 10 h. The mixture was then filtered, and the filter cake was dried to obtain the quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 89% and a melting point of 164 °C.

[0063] Example 4

[0064] 12 g (0.101 mol) of the dimethylaminocaprolactam / caprolactam copolymer obtained in Preparation Example 2 and 25 g (0.115 mol) of 1,4-dibromo-n-butane were added to a 50 mL reaction vessel. The vessel was evacuated and purged with nitrogen four times. The reaction was carried out for 6 h at 180 °C and 0.3 MPa under a nitrogen atmosphere. The reaction product was transferred to a 1 L extraction vessel at 25 °C and extracted with 100 mL of ethanol for 12 h. The mixture was then filtered, and the filter cake was dried to obtain the quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 89% and a melting point of 180 °C.

[0065] Example 5

[0066] Prepared according to the method of Example 1, except that: the caprolactam copolymer is the dimethylaminocaprolactam / caprolactam copolymer obtained in Preparation Example 3, and the other steps are the same, to obtain quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 90% and a melting point of 153°C.

[0067] Example 6

[0068] Prepared according to the method of Example 1, except that the temperature of the quaternization reaction is 165°C, and the other steps are the same, to obtain a quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 71% and a melting point of 198°C.

[0069] Comparative Example 1

[0070] 18 g of the product obtained in Preparation Example 2 was dissolved in 200 mL of trifluoroethanol, and 4.5 g of hexane was added. The mixture was reacted in an oil bath at 40 °C for 12 h. The reaction solution was precipitated in ethyl acetate, centrifuged, and dried to obtain a quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 92% and a melting point of 175 °C.

[0071] Comparative Example 2

[0072] 10 g (0.084 mol) of the dimethylaminocaprolactam / caprolactam copolymer obtained in Preparation Example 2 and 30 g (0.136 mol) of bromodecane were added to a 50 mL reaction vessel, and the mixture was evacuated and purged with nitrogen four times. The reaction was carried out for 6 h at 130 °C and 0.3 MPa under a nitrogen atmosphere. The reaction product was transferred to a 1 L extraction vessel at 60 °C and extracted with 100 mL of ethanol for 12 h. The mixture was then filtered, and the filter cake was dried to obtain the quaternized dimethylaminocaprolactam / caprolactam copolymer with a yield of 10% and a melting point of 195 °C.

[0073] The quaternized caprolactam copolymers obtained in the examples and comparative examples were subjected to NMR measurements, and the quaternization rate was calculated. The results are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] As can be seen from the results in Table 1, the examples using the caprolactam copolymer quaternization method described in this invention have significantly better antibacterial properties and quaternization efficiency.

[0078] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for quaternizing caprolactam copolymers, characterized in that, The method includes: Under solvent-free conditions, caprolactam copolymer and quaternizing agent are subjected to quaternization reaction to obtain quaternized caprolactam copolymer. The temperature of the quaternization reaction is from Tm-40℃ to Tm+40℃, where Tm is the melting point of caprolactam copolymer.

2. The method according to claim 1, wherein, The caprolactam copolymer is a caprolactam copolymer containing tertiary amine branches, preferably a copolymer having the structure of formula (I). Among them, R1 and R2 are each independently selected from C. 1-24 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-12 Alicyclic hydrocarbon group, substituted or unsubstituted C 6-18 Aryl and C 7-30 Alkyl aryl, or R1 and R2 groups on the same nitrogen atom together with the attached N atom to form a 5-7 member saturated or unsaturated heterocycle, where x and y represent the molar content of the copolymer units in their respective brackets, where x is selected from 0.01-0.3 and y is selected from 0.7-0.99, and x+y=1; Preferably, the R1 and R2 groups are each independently selected from C 1-12 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-6 Alicyclic hydrocarbon group, substituted or unsubstituted C 7-16 The aryl group, or R1 and R2 together with the attached N atom, form a 5-6 member saturated or unsaturated heterocycle; more preferably, the R1 and R2 groups are each independently selected from methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, allyl, phenyl or benzyl, or R1 and R2 together with the attached N atom form a tetrahydropyrrole or hexahydropyridyl.

3. The method according to claim 1 or 2, wherein, The quaternizing agent has the structure shown in formula (II) or formula (III): R3-Hal(II), Hal-R4-Hal(III), Among them, the R3 group is selected from hydrogen, C 1-24 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-12 Alicyclic hydrocarbon group, substituted or unsubstituted C 6-18 Aryl or C 7-30 alkylaryl; Preferably, the R3 group is selected from hydrogen, C 1-12 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-6 Alicyclic hydrocarbon group, substituted or unsubstituted C 7-16 Aryl; more preferably, the R3 group is selected from hydrogen, methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, phenyl or benzyl; The R4 group is selected from C 1-24 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-12 Alicyclic alkylene groups, substituted or unsubstituted C 6-18 aryl or C 7-30 Alkyl arylidene; Preferably, the R4 group is selected from hydrogen, C 1-12 Straight-chain or branched aliphatic hydrocarbon groups, substituted or unsubstituted C 3-6 Alicyclic hydrocarbon group, substituted or unsubstituted C 7-16 Aryl; more preferably, the R4 group is selected from hydrogen, methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, phenyl or benzyl; Here, Hal represents halogen.

4. The method according to any one of claims 1-3, wherein, The quaternization reaction takes 1-12 hours, preferably 3-6 hours. Preferably, the temperature of the quaternization reaction is from Tm-30℃ to Tm-10℃.

5. The method according to any one of claims 1-4, wherein, The molar ratio of the caprolactam copolymer to the quaternizing agent is 1:1-20, preferably 1:1.1-10.

6. The method according to any one of claims 1-5, wherein, The method further includes: extracting and filtering the mixture after the quaternization reaction, and drying the resulting filter cake to obtain the quaternized caprolactam copolymer.

7. The method according to claim 6, wherein, The extractant used for extraction is selected from fatty alcohols, preferably C1-C4 fatty alcohols; further selected from methanol and / or ethanol.

8. The method according to claim 6 or 7, wherein, The extraction temperature is 25-60℃, and the extraction time is 10-15h.

9. The method according to any one of claims 6-8, wherein, The filtrate obtained from filtration is separated to obtain unreacted quaternizing reagent and extractant, which are then reused.

10. The quaternized caprolactam copolymer obtained by the method of any one of claims 1-9.

Images