WO2013170534A1

WO2013170534A1 - Method for preparing homopolymer k90 aqueous solution of n-vinyl butyrolactam with low residual monomer

Info

Publication number: WO2013170534A1
Application number: PCT/CN2012/079061
Authority: WO
Inventors: 王宇; 吴美玲; 陈占
Original assignee: 上海宇昂化工科技发展有限公司
Priority date: 2012-05-16
Filing date: 2012-07-23
Publication date: 2013-11-21
Also published as: CN102633926B; GB2517604A; GB201420099D0; GB2517604B; CN102633926A

Abstract

Disclosed in the present invention is a method for preparing a homopolymer K90 aqueous solution of N-vinyl butyrolactam with low residual monomer, comprising: using 10-35% weight of an aqueous solution of N-vinyl butyrolactam monomer as a raw material in the presence of an inert gas, at a polymerization temperature of 55°C—90°C, carrying out a reaction under stirring for 2.5-4.5 h and during the reaction adding an initiator in batches, the initiator being a mixture of azodiisobutyronitrile and azobisisoheptonitrile and having a total amount of 0.01%-3% of the mass of N-vinyl butyrolactam monomer; after the K value of this system reaches 90-102, maintaining the temperature overnight at 95°C, adding a mixed acid in batches to adjust the pH to be at 2.0-7.0; during the removal of the residual monomer, the mixed acid being formed by mixing two acids selected from propane diacid, sulphuric acid and hydrochloric acid, so as to obtain 10-35% by weight of a colourless and transparent product residual monomer below 10 ppm and a stable K value of 90-102. The present invention is ingenious in design and simple in preparation. The prepared homopolymer K90 aqueous solution of N-vinyl butyrolactam has low residual monomer below 10 ppm, is colourless and stable in K value, and suitable for a large scale of popularization and application.

Description

Low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution preparation method

The invention relates to the technical field of compound preparation, in particular to the technical field of preparation of N-vinyl butyrolactam homopolymer, and specifically relates to a method for preparing a low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution. Background technique

Homo-N-vinyl butyrolactam is a non-ionic water-soluble polymer compound. The homopolymer N-vinyl butyrolactam is easily soluble in water, alcohols, amines and hydrocarbons, and can be almost all other cations. , anionic and nonionic cosmetic polymers are compounded. It has excellent solubility, biocompatibility, physiological inertness, film formation and membrane protection. Homopolymerized N-vinyl butyrolactam K90 is the most distinctive and widely used fine chemical variety of N-vinyl amide homopolymers and therefore has a wide range of uses. Application of homopolymeric N-vinyl butyrolactam K90 in the daily chemical industry: In daily cosmetics, homopolymerized N-vinyl butyrolactam K90 has good dispersibility and film formability, and can be used as a setting liquid, Hair styling and mousse styling agents, hair conditioner sunscreens, shampoo foam stabilizers, wave styling agents and dispersing agents and affinity agents in hair dyes. Adding homopolymerized N-vinyl butyrolactam to creams, sunscreens, and depilatory agents enhances moisturizing and lubricating effects. Application of homopolymeric N-vinyl butyrolactam in industrial and high-tech fields: homopolymerized N-vinyl butyrolactam can be used as surface coating agent in pigments, printing inks, textiles, printing and dyeing, color picture tubes, dispersion Agent, thickener, binder. Homopolymerized N-vinyl butyrolactam improves the adhesion of binders to metals, glass, plastics, etc. In addition, homopolymerized N-vinyl butyrolactam in separation membranes, paints and coatings, optical fibers, lasers Applications in emerging high-tech fields such as video discs are also growing. Pharmaceutical grade homopolymerization of N-vinyl butyrolactam: homopolymerization N-vinyl butyrolactam has a wide range of applications in medicine and is one of the three major medicinal excipients advocated internationally. The most widely used are tablets, granules of adhesives. Homopolymerized N-vinylbutyrolactam can also be used as a glidant for gums, as an antidote and lubricant for eye drops, as a cosolvent for injections, as a dispersant for liquid preparations, as a stabilizer for enzymes and thermosensitive drugs. There are hundreds of drugs that use PVP products as excipients.

Since the viscosity of homopolymerized N-vinyl butyrolactam K90 is higher than that of other low molecular weight homopolymerized N-vinyl butyrolactam, the reaction residual raw materials are higher, and the elimination of residual raw materials is a bottleneck and K value at present. Very easy to degrade. Therefore, if it is possible to produce a homopolymerized N-vinyl butyrolamide K90 with a colorless and K-stabilized reaction residual material below 10 ppm, it will be of epoch-making significance for pharmaceutical industry accessories. Summary of the invention

The object of the present invention is to overcome the above disadvantages of the prior art, and to provide a method for preparing a low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution, the low residual single N-vinyl butyrolactam homopolymer Design of preparation method of K90 aqueous solution Ingeniously, the preparation of the single-sheet, the residual residue of the low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution is below 10 ppm, colorless and stable in K value, and is suitable for large-scale popularization and application.

In order to achieve the above object, the preparation method of the low residual single N-vinyl butyrolactam homopolymer K90 7j solution of the present invention is characterized by 10 to 35% by weight of N-vinyl in the presence of an inert gas. The aqueous solution of butyramide monomer is used as raw material, and the initiator is added in batches at a polymerization temperature of 55 ° C to 90 ° C for 2.5 h to 4.5 h. The initiators are azobisisobutyronitrile and azo For the mixture of isoheptonitrile, the total amount of initiator added is 0.01%~3% of the mass of N-vinyl butyrolactam monomer, and the K value of the system is 90~102, and the temperature is eliminated at 95 °C overnight. In a single process, the pH is adjusted to 2.0 to 7.0 by batch and mixed acid, wherein the mixed acid is mixed with two acids selected from the group consisting of malonic acid, sulfuric acid and hydrochloric acid, thereby obtaining a residue of 10 to 35% by weight at 10 ppm. The following is a colorless transparent low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution having a K value of 90 to 102.

The step of adding the hair to the batch can be carried out by any suitable step. Preferably, the batch is added to the hair emulsion, and the following steps are specifically used: first adding 40 to 60% of the total weight of the initiator, Start the polymerization. After 1 h, add 20-30% of the total weight of the initiator. After 0.5 h of reaction, add 10~20% of the total weight of the initiator. After 0.5 h, add 10% of the total weight of the initiator. 30%, continue to react 0.5-2.0 h.

The ratio of the azobisisobutyronitrile and the azobisisoheptanenitrile in the initiator may be arbitrary, preferably, the azobisisobutyronitrile and the azodiamine in the initiator The ratio of isoheptonitrile is 3:7~7:3.

The time interval of adding the mixed acid to the mixed acid and adjusting the pH to 2.0~7.0 may be arbitrary. Preferably, the time interval of adding the mixed acid to the mixed acid and adjusting the pH to 2.0~7.0 is l~5h.

The mixed acid adjusted pH is 2.0~7.0, and the mixed acid added may be the same or different. Preferably, the batch is mixed with acid to adjust the pH to 2.0~7.0. The mixed acid added is different.

The pH of the batch and the mixed acid adjusted to pH 2.0 to 7.0 may be the same or different, and preferably, the batch is mixed with the acid to adjust the pH to 2.0 to 7.0. The pH of the adjustment is different.

The mixed acid may be mixed in any ratio of any two of malonic acid, sulfuric acid and hydrochloric acid. Preferably, the mixed acid is a mixed acid of malonic acid and citric acid, or a mixture of citric acid and hydrochloric acid. Acid, or a mixed acid of malonic acid and hydrochloric acid.

The beneficial effects of the present invention are specifically as follows: the low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution of the present invention is prepared by using 10 to 35% by weight of N-vinylbutylene in the presence of an inert gas. The amide monomer aqueous solution is used as a raw material, and the initiator is added in batches at a polymerization temperature of 55 ° C to 90 ° C for 2.5 h to 4.5 h. The initiators are azobisisobutyronitrile and azobisglyoxime. The mixture of nitriles, the total amount of initiator added is 0.01%~3% of the mass of N-vinyl butyrolactam monomer, and the K value of the system is 90~102, and the process of eliminating the residual residue is carried out at 95 °C overnight. Batch in batch The mixed acid is adjusted to have a pH of 2.0 to 7.0, wherein the mixed acid is prepared by mixing two acids selected from the group consisting of malonic acid, sulfuric acid and hydrochloric acid, thereby obtaining a residue of 10 to 35% by weight below 10 ppm and a K value of 90. ~102 colorless transparent low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution, ingeniously designed, prepared a single, low residual single N-vinyl butyrolactam homopolymer K90 aqueous solution residue It is only below lOppm, colorless and stable in K value, suitable for large-scale popularization and application. DRAWINGS

Fig. 1 shows the change of residual monomer N-vinyl butyrolactam content in different polymerization time. detailed description

In order to more clearly understand the technical content of the present invention, the following embodiments are specifically described.

(-) Raw materials and reagents:

Table 1 Raw materials and reagents

Name Specifications Manufacturer

N-vinyl butyrolactam industrial grade (reduced pressure distillation) Shanghai Yuang Chemical Technology Development Co., Ltd. Azobisisobutyronitrile (AIBN) Chemically pure Qingdao Runxing Photoelectric Material Co., Ltd. Azobisisoheptanenitrile (AVBN) Chemistry Pure Qingdao Runxing Photoelectric Material Co., Ltd. Citric Acid Chemical Pure Chinese Medicine Group Pharmaceutical Co., Ltd. Malonate Analysis Pure Sinopharm Group Pharmaceutical Co., Ltd. Hydrochloric Acid Pure Chinese Medicine Group Pharmaceutical Co., Ltd. Nitrogen 99% Shanghai Hukang Gas

(2) Instruments and equipment:

Table 2 Instruments and equipment

Name Specifications Manufacturer

Rotary vane vacuum oil pump 2XZ-2 Zhejiang Huangyan Instrument Factory

Rotary evaporator RE52CS Shanghai Yarong Biochemical Instrument Factory

Three-necked flask 250 ml Shanghai Heshang Glass Instrument Co., Ltd. Constant temperature oil bath HH-WO Shanghai Heshang Glass Instrument Co., Ltd. U-shaped viscometer Φ0.5 Shanghai Heshang Glass Instrument Co., Ltd. Electric mixer S312 Shanghai Meiyingpu instrument manufacturing Limited Analytical balance one FA2004 Shanghai Liangping Instrument Factory

Constant Pressure Dropping Funnel 100 ml Shanghai Heshang Glass Instrument Co., Ltd. Pipette 10 ml Shanghai Heshang Glass Instrument Co., Ltd. Alkaline Burette 50 ml Shanghai Heshang Glass Instrument Co., Ltd.

(III) Polymer homopolymerization N-vinyl butyrolactam K90 preparation

The air in the reaction system is removed by an inert gas such as N _{2 , and} the reaction of the experiment is carried out by using 10 to 35% of an aqueous solution of N-vinyl butyrolactam monomer, and then adding distilled water and N-vinyl butyrolactam monomer. In a three-necked flask, place in a constant temperature oil bath, raise the temperature to 55 °C ~ 90 °C, and add nitrogen gas while stirring, adding a total of 0.01% ~ 3% of the initiator (relative to the monomer N-vinyl butyl Amide mass ratio), the initiator is a mixture of azobisisobutyronitrile and azobisisoheptanonitrile, first adding 40~60% of the total weight of the initiator, starting polymerization, after lh, adding 20% of the total weight of the initiator 30%, after 0.5 h of continuous reaction, add 10~20% of the total weight of the initiator. After 0.5 h, add 10~30% of the total weight of the initiator, continue to react for 0.5-2.0 h, and wait for the K value of the system to reach 90. ~102, adding mixed acid (mixed from two acids selected from malonic acid, sulfuric acid and hydrochloric acid) to adjust the pH to 2.0~7.0, terminate the reaction, heat up to 95 °C, and keep the residual raw materials overnight. The mixed acid is added in batches. Through this experiment, a colorless transparent PVPK90 polymer aqueous solution having a concentration of 10 to 35% is obtained, and the residual N-vinyl butyrolactam content is 10 ppm or less, and the K value of the obtained polymer solution (at a weight concentration of 1%) Aqueous solution determination) is 90-102 ₀

(4) Mechanism discussion

Fikentscher first developed an aqueous solution polymerization method for N-vinylpyrrolidone. When it was initiated with an azo initiator, the polymerization mechanism was as follows:

Chain trigger:

Chain delivery:

Stop:

Wherein RN≡NR represents an azo initiator, R represents an organic group, and N is a nitrogen atom.

(v) Results and discussion

5.1 Elimination of residual raw materials

5.1.1 Results of elimination of residual raw materials by different acids

Table 3 Effect of different acids on residual results

Acid name Initial residue (%) After 12h residue (%) Residual reduction (%) Malonic acid / sulfuric acid / hydrochloric acid 1.25 0.00089 92.88

Citric acid 1.248 0.0051 99.59

Acetic acid 1.2469 0.096 92.30

When acetic acid and citric acid are used alone to eliminate residual raw materials, not only the problem of K-degradation occurs, but also in the process of eliminating residual raw materials, yellowing of the solution occurs, and the content of residual raw materials is above 0.01%, and When the acid/sulfuric acid/hydrochloric acid complex acid is used, the above two problems can be solved by first using two kinds of acids, eliminating the residual raw materials for 3 hours, and then selecting the other two kinds of the above three acids to eliminate the residual raw materials for 5 hours. According to Table 3, the content of residual raw materials is reduced to below 10 ppm.

5.1.2 Effect of pH on K value during the process of adding acid to eliminate residual raw materials

Table 4 Effect of pH on K value

pH before adding acid K value after adding acid for 12h

<2.0 96 86.2

2-5 96.2 95.86 >5 96.2 105

It can be seen from Table 4 that if the pH is lower than 2.0, the acidity is too strong, and the homopolymerized N-vinyl butyrolactam K90 is unstable and easily decomposes, resulting in a decrease in the K value; if the pH is higher than 7.0, it is continuously stirred and heated. Under the conditions, the reaction will be polymerized, resulting in an increase in the viscosity of the product and an increase in the K value. When the pH is between 2.0 and 7.0, the product is relatively stable, and even if it is overnight, the K value does not degrade. In summary, the optimum pH is 2.0 to 7.0 in the process of eliminating residual raw materials.

5.1.3 Effect of pH on the color of the solution during the addition of acid to remove residual raw materials

Table 5 Effect of pH on the color of the solution

pH before the acid is introduced into the acid, the color of the solution is 12 hours after the acid is added.

2.5 or less colorless yellow

2.5 or more colorless, colorless

As can be seen from Table 5, when the solution is below pH, it is unstable and the solution turns yellow. According to Table 3, Table 4 and Table 5, when adjusting pH, we should choose pH between 2.0 and 7.0. The prepared homo-N-vinyl butyrolactam K90 solution is colorless and the residual raw materials are 10 Below the ppm, the K value is stable.

5.2 Azo initiator

Table 6 Reactions of different initiators

Initiator name initiator starts to initiate decomposition activation energy / product residue /% temperature rc ( KJ.mol" ¹ ) single /% azobisisoheptanenitrile 0.1 54 122 1.09 azobisisobutyronitrile 0.025 71 129 0.02 azo Mixture of diisoheptanenitrile and azobisisobutyronitrile 0.068 54 - 0.00087 It can be seen from Table 6 that only azobisisoheptanenitrile has low activation energy relative to azobisisobutyronitrile due to its low activation energy. At 54 °C, azobisisoheptanenitrile will be thermally decomposed to generate free radicals and nitrogen, but because of its rapid initiation rate, it becomes faster and more viscous than azobisisobutyronitrile, but the initiation speed is fast, resulting in residue. The raw material is very high, which is its fatal shortcoming. The raw materials used only by it are very high; but with azobisisobutyronitrile, the speed is slower, but the starting temperature is higher, the advantage is that the residual single is better than only The azobisisoheptanenitrile is low; the two are mixed, and the hydrazine is added in portions to prepare a colorless, almost no raw material taste, and the residual raw material is 10 ppm or less.

5.3 Effect of polymerization time on residual raw materials

When the homopolymerized N-vinyl butyrolactam K90 was prepared, the influence of the polymerization time on the residual monomer content was examined under the same conditions.

Table 7 Effect of polymerization time on residual raw materials Polymerization time (h) 0 1 2 3 4

Residual NVP content (%) 100 35.02 10.03 0.07 0.01 0.0007

According to Table 7, the corresponding residual monomer N-vinyl butyrolactam content as a function of polymerization time is shown in Figure 1. It can be seen from Table 7 and Figure 1. As the polymerization time progresses, the content of residual monomer N-vinyl butyrolactam gradually decreases, but the rate of decrease is gradually slowed down. When the reaction reaches about 3 hours, the residual monomer N- The content of vinyl butyrolactam will tend to be stable and will not decrease. Therefore, when conducting experiments on homopolymerization of N-vinyl butyrolactam K90, the time should be chosen at 2.51! ~ 4.5h is more appropriate.

(6) Characterization

6.1 Determination of K value

Usually we use the K value of the Fikentscher formula to characterize the molecular weight of homopolymeric N-vinyl butyrolactam. The K value is a parameter that is only related to molecular weight and does not change with the concentration of homopolymeric N-vinyl butyrolactam. A commonly used method for determining the K value is the viscosity method. The Ubbel viscometer measures the relative viscosity r)r of the solution against water at a water bath temperature of 25 ± 0.2.

The K value is calculated according to the Fikentscher formula as follows (Li Xinming. A method for eliminating residual monomer N-vinylpyrrolidone in polymers [P]. CN 1712432, 2005-12-28 ):

_K = [300Clg^ _r + (C + 1.51g^) ² ] ^1/2 + 1.5C lg^ - C

~ 0.15C + 0.003C ²

In the formula:

K is the Fikentscher constant;

C is the number of grams of homopolymerized N-vinyl butyrolactam dissolved in 0.1 L solution

η _Γ is the relative viscosity (the ratio of the solution effluent time to the pure solvent effluent time Τ / Το)

6.2 Residual monomer content

The determination of the residual monomer content in the homopolymerized N-vinyl butyrolactam is based on the method specified in the 26th edition of the United States Pharmacopoeia. Take 10 g of homopolymerized N-vinyl butyrolactam (accurate to 0.002 g, based on anhydrous matter), dissolve in 80 ml of distilled water, add lg sodium acetate, and titrate with 0.1 mol/L iodine solution until the solution no longer fades. Add 3 ml of 0.1 mol/L iodine solution for 10 minutes, then titrate excess iodine with 0.1 mol/L sodium thiosulfate. Add 3 ml of starch indicator to the end point and continue titration to the solution. The color disappeared and was compared to the blank experiment.

Result calculation:

In the formula: Vi - titration of the sodium thiosulfate solution (mL) consumed by the blank sample;

V ₂ ― titration of the sodium thiosulfate solution (mL) consumed by the sample;

The concentration of sodium N-gram gram sodium solution (mol / L);

Quality of 0.106-1 mmol/L N-vinylpyrrolidone (g);

M—the mass of the sample (g). The invention will be more specifically illustrated by the following examples, but the invention is not limited by these examples. In the following, unless otherwise stated, "parts by weight" is only expressed as "parts", and "% by weight" is only expressed as "%".

Example 1

The experimental reaction concentration was 18% by weight of an aqueous solution of N-vinyl butyrolactam monomer, and the total weight of the initiator added was 0.32% (relative to the monomer N-vinyl butyrolactam mass ratio). 287 parts of water was added as a reaction solvent to a reaction vessel equipped with a gas inlet, a condenser, and a thermometer, and nitrogen was introduced while stirring, and the air in the reaction vessel was drained to form a nitrogen atmosphere. Then, after heating in an oil bath to bring the internal temperature of the reaction vessel to 70 ° C, 63 parts of N-vinyl butyrolactam and 0.08 parts of an initiator produced by Shanghai Yuang Chemical Technology Development Co., Ltd. were added, and the initiator was Azobisisobutyronitrile/azobisisoheptanenitrile = 5/5 composition. After 1 h, add 0.06 parts of initiator, continue the reaction for 0.5 h, continue to add 0.04 parts of initiator, and after 0.5 h, make up the force. After 0.02 parts of initiator, continue to react for 1.5 h, add malonic acid/hydrochloric acid in a ratio of mixed acid to the vessel, adjust the pH to 5.5, and raise the temperature to 95 °C. After removing the residual raw materials for 3 h, add sulfuric acid. /Nitrate mixture of hydrochloric acid, adjust the pH to 4.0, and remove the residual raw material for 5 h, the concentration of N-vinyl butyrolactam in the reaction solution is 8 ppm, thereby obtaining a colorless transparent PVPK90 polymer with a concentration of 18%. The aqueous solution, the K value of the obtained polymer solution (measured as an aqueous solution having a weight concentration of 1%) was 98.01.

Comparative example 1 :

Except that the residual raw materials were eliminated after the reaction, the mixed acid in Example 1 was changed to only sulfuric acid, and the rest of the experimental procedures were identical to those in Example 1, and an aqueous solution having a PVPK90 concentration of 18% was prepared by polymerization, and residual N- The vinyl butyrolactam concentration was 51 ppm, and the K value of the obtained polymer solution (measured as a 1% by weight aqueous solution) was 97.84.

Comparative example 2

The experiment procedure in Example 1 was changed to azobisisoheptanenitrile, and the rest of the experimental procedure was identical to that in Example 1. The concentration of N-vinylbutyrolactam in the reaction solution for preparing PVPK90 polymer was 102 ppm. , a colorless transparent PVPK90 polymer aqueous solution having a concentration of 18%, and the K value (measured by an aqueous solution having a weight concentration of 1%) of the obtained polymer solution was 110.11. Example 2: Different from Example 1, the total weight of the added initiator is: 0.01% (relative to the monomer NVP mass ratio); heating with an oil bath causes the internal temperature of the reaction vessel to reach 90 ° C; the initiator is composed of azo Nitrile / azobisisoheptanenitrile = 7 / 3 composition; the first addition of 0.003 parts of initiator, lh, then add 0.0012 parts of initiator, continue to react for 0.5 h, continue to add 0.0006 parts of initiator, 0.5 After h, 0.0012 parts of initiator is added, and the polymerization reaction is continued for 0.5 hour after the addition of the initiator; the first mixed acid is a mixed acid of malonic acid/hydrochloric acid, the pH is adjusted to 7, and the second mixed acid is sulfuric acid/ Hydrochloric acid = 8/2 mixed acid, adjusted to pH 5, two acid addition time interval lh. Prepare a PVPK90 polymer in a reaction solution with a N-vinyl butyrolactam concentration of 5 ppm and a concentration of 18% of a colorless transparent PVPK90 polymer aqueous solution. The K value of the obtained polymer solution (at a weight concentration of 1%) The aqueous solution was determined to be 95.01. Example 3

Different from Example 1, the total weight of the added initiator is: 3% (relative to the monomer NVP mass ratio); heating with an oil bath causes the internal temperature of the reaction vessel to reach 55 ° C; the initiator is composed of azo Nitrile / azobisisoheptanenitrile = 3 / 7 composition; the first addition of 1.134 parts of the initiator, 1 h later, add 0.378 parts of the initiator, continue the reaction for 0.5 h, continue to add 0.189 parts of the initiator, After 0.5 h, 0.378 parts of initiator was added, and the polymerization reaction was continued for 2 hours after the addition of the initiator; the first mixed acid was a mixed acid of sulfuric acid/hydrochloric acid=3/7, the pH was adjusted to 5, and the second mixed acid was C. The diacid/sulfuric acid = 1/9 mixed acid was adjusted to pH 2, and the acid addition time was 5 h. An aqueous solution having a PVPK90 concentration of 18% was prepared, and the residual N-vinyl butyrolactam concentration was 7.95 ppm, and the K value of the obtained polymer solution (measured by an aqueous solution having a weight concentration of 1%) was 99.01. Example 4

The concentration of the reaction in this experiment was 10%, and the total weight of the initiator added was 0.32% (relative to the mass ratio of the monomer N-vinyl butyrolactam). 567 parts of water was added as a reaction solvent to a reaction vessel equipped with a gas inlet, a condenser, and a thermometer, and nitrogen was introduced while stirring, and the air in the reaction vessel was drained to form a nitrogen atmosphere. Next, after heating in an oil bath to bring the internal temperature of the reaction vessel to 55 ° C, 63 parts of N-vinyl butyrolactam and 0.08 parts of an initiator produced by Shanghai Yuang Chemical Technology Development Co., Ltd. were added, and the initiator was Azobisisobutyronitrile/azobisisoheptanenitrile = 5/5 composition. After 1 h, add 0.04 parts of initiator, continue to react for 0.5 h, continue to add 0.02 parts of initiator, 0.5 h, add 0.06 parts of initiator, continue reaction for 1.5 h, then add malonic acid to the container. / Sulfuric acid is mixed with acid in equal proportion, the pH is adjusted to 5.5, the temperature is raised to 95 °C, the residual raw material is removed for 3 h, and then a mixture of malonic acid/hydrochloric acid is added to adjust the pH to 4.0 to eliminate the residue. After 5 h of the raw material, the concentration of N-vinyl butyrolactam in the reaction solution was 1 ppm, thereby obtaining a colorless transparent PVPK90 polymer aqueous solution having a concentration of 10%, and the K value of the obtained polymer solution (at a weight concentration of 1) The % aqueous solution was determined to be 93.35. Example 5

The concentration of the reaction in this experiment was 35%, and the total weight of the initiator added was 0.32% (relative to the mass ratio of the monomer N-vinyl butyrolactam). To a reaction vessel equipped with a gas inlet, a condenser, and a thermometer, 117 parts of water was added as a reaction solvent, and nitrogen was introduced while stirring, and the air in the reaction vessel was drained to form a nitrogen atmosphere. Next, after heating in an oil bath to bring the internal temperature of the reaction vessel to 95 ° C, 63 parts of N-vinyl butyrolactam and 0.08 parts of an initiator produced by Shanghai Yuang Chemical Technology Development Co., Ltd. were added, and the initiator was Azobisisobutyronitrile/azobisisoheptanenitrile = 5/5 composition. After 1 h, add 0.04 parts of initiator, continue to react for 0.5 h, continue to add 0.04 parts of initiator, 0.5 h, add 0.04 parts of initiator, continue to react for 1.5 h, then add hydrochloric acid / sulfuric acid to the container. Mix the acid in equal proportion, adjust the pH to 5.5, and raise the temperature to 95 °C. After removing the residual raw materials for 3 h, add the ratio of malonic acid/sulfuric acid to adjust the pH to 4.0 to eliminate the residual raw materials. After h, the concentration of N-vinyl butyrolactam in the reaction solution was 2 ppm, thereby obtaining a colorless transparent PVPK90 polymer aqueous solution having a concentration of 35%, and the K value of the obtained polymer solution (at a weight concentration of 1%) The aqueous solution was determined to be 95.5. The purpose of introducing nitrogen into the system of the present invention is to remove oxygen in the reaction system, to carry out the reaction under an inert gas, to have oxygen inhibition, to accelerate the chain termination reaction, and to lower the molecular weight of the polymer. By experimenting with different acids, it was found that the use of malonic acid/sulfuric acid/hydrochloric acid complex acid to eliminate residual raw materials and added in batches can not only reduce the residual raw materials to less than 10 ppm, but also eliminate residual raw materials. Moreover, the color of the solution does not change. It has been found through experiments that pH has a great influence on the color of the solution or the stability of the product. If the pH is too high or too low, the K value will be degraded or increased. When the residual raw materials are eliminated, the pH is selected between 2.0 and 7.0. Suitable. On the selection of the initiator, a mixture of azobisisobutyronitrile and azobisisoheptanonitrile should be selected and added in batches.

Therefore, the present invention has studied various factors affecting the product from the aspects of acid, initiator, pH, polymerization time, etc., and prepared the mixed acid and composite initiating system specially prepared by the present invention, and adjusting the initiator and the acid addition sequence to prepare The product has a high stability product with a residual value of less than 10 ppm and a K value, and its product conforms to the latest national Pharmacopoeia requirements of USP32, BP2006, EP6 and other European and American countries to homopolymerize N-vinyl butyrolactam K90.

In summary, the preparation method of the low-residue monoterpene-vinyl butyrolactam homopolymer Κ90 aqueous solution of the invention is ingeniously designed, and the preparation of the low residual single N-vinyl butyrolactam homopolymer Κ90 aqueous solution is prepared. The residual order is below lOppm, colorless and stable in K value, suitable for large-scale popularization and application.

In this specification, the invention has been described with reference to specific embodiments thereof. However, it will be apparent that various modifications and changes can be made without departing from the spirit and scope of the invention. Accordingly, the specification and figures are to be regarded as illustrative and not limiting.

Claims

Rights request

1. A method for preparing a low-residue monomer N-vinyl butyrolactam homopolymer K90 aqueous solution, which is characterized in that, in the presence of inert gas, 10 to 35% by weight of N-vinyl butyrolactam monomer is used. The aqueous solution is used as the raw material. At the polymerization temperature of 55°C~90°C, the initiator is added in batches during the stirring reaction for 2.5h-4.5h. The initiator is a mixture of azobisisobutyronitrile and azobisisoheptanitrile. , the total amount of initiator added is 0.01%~3% of the mass of N-vinylbutyrolactam monomer. When the K value of the system reaches 90-102, incubate it overnight at 95 °C to eliminate residual orders in batches. Add a mixed acid to adjust the pH to 2.0~7.0. The mixed acid is composed of two acids selected from malonic acid, sulfuric acid and hydrochloric acid, so as to obtain a residual monomer of 10~35% by weight. The JLK value is stable below 10 ppm. A colorless and transparent aqueous solution of N-vinyl butyrolactam homopolymer K90 with low residual content of 90~102.

2. The preparation method of low-residue N-vinylbutyrolactam homopolymer K90 aqueous solution according to claim 1, characterized in that the step of adding the initiator in batches specifically adopts the following steps: Add the initiator first 40~60% of the total weight, start polymerization. After 1 hour, add 20~30% of the total weight of the initiator. After continuing the reaction for 0.5 h, add 10~20% of the total weight of the initiator. After 0.5 h, add 10~30% of the total weight of the initiator, and continue the reaction for 0.5-2.0 h.

3. The preparation method of low-residue N-vinylbutyrolactam homopolymer K90 aqueous solution according to claim 1, characterized in that, the azobisisobutyronitrile and the azobisisobutyronitrile in the initiator The ratio of diisoheptonitrile is 3:7~7:3.

4. The preparation method of the low-residue N-vinyl butyrolactam homopolymer K90 aqueous solution according to claim 1, wherein the mixed acid is added in batches to adjust the pH to 2.0~7.0. The time interval is l~5h.

5. The preparation method of the low-residue N-vinyl butyrolactam homopolymer K90 aqueous solution according to claim 1, wherein the mixed acid is added in batches to adjust the pH to 2.0 to 7.0 each time. The mixed acid added is different.

6. The preparation method of the low-residue N-vinyl butyrolactam homopolymer K90 aqueous solution according to claim 1, wherein the mixed acid is added in batches to adjust the pH to 2.0 to 7.0 each time. The pH is adjusted differently.

7. The preparation method of low-residue N-vinylbutyrolactam homopolymer K90 aqueous solution according to claim 1, characterized in that the mixed acid is a mixed acid of malonic acid and citric acid, or lemon A mixed acid of acid and hydrochloric acid, or a mixed acid of malonic acid and hydrochloric acid.