阅读说明：本技术 一种微通道反应器连续化合成尼龙盐溶液的方法 (Method for continuously synthesizing nylon salt solution by using microchannel reactor ) 是由 王根林 吴健 徐志斌 丁克鸿 徐林 聂庆超 卞辰超 史青 王浩 冯青宇 汪贵城 于 2021-06-30 设计创作，主要内容包括：本发明提供一种微通道反应器连续化合成尼龙盐溶液的方法,所述方法包括：含有机二酸的水溶液与含有机二胺的液相物料通入微通道反应器中进行反应,得到尼龙盐溶液。所述方法工艺流程简单,反应时间短,反应效率高,可操作性强,安全性高,易于工业化生产,且其制得的尼龙产品色度优良,应用前景广阔。(The invention provides a method for continuously synthesizing a nylon salt solution by using a microchannel reactor, which comprises the following steps: and introducing the aqueous solution containing the organic diacid and the liquid-phase material containing the organic diamine into a microchannel reactor for reaction to obtain the nylon salt solution. The method has the advantages of simple process flow, short reaction time, high reaction efficiency, strong operability, high safety and easy industrial production, and the prepared nylon product has excellent chromaticity and wide application prospect.)

1. A method for continuously synthesizing a nylon salt solution by using a microchannel reactor is characterized by comprising the following steps:

and introducing the aqueous solution containing the organic diacid and the liquid-phase material containing the organic diamine into a microchannel reactor for reaction to obtain the nylon salt solution.

2. The method of claim 1, wherein the organic diacid comprises any one of adipic acid, terephthalic acid, glutaric acid, or sebacic acid, or a combination of at least two thereof;

preferably, the organic diamine comprises any one of hexamethylene diamine, pentamethylene diamine, p-phenylene diamine or decamethylene diamine or a combination of at least two of them.

3. The method according to claim 1 or 2, wherein the concentration of the organic diacid in the aqueous solution containing the organic diacid is 0.01 to 1000g/L, preferably 500 to 800 g/L.

4. The method according to any one of claims 1 to 3, wherein the liquid phase material containing the organic diamine is an aqueous solution containing the organic diamine or a molten liquid phase of the organic diamine;

preferably, the concentration of the organic diamine in the liquid phase material containing the organic diamine is 0.01-1000 g/L, preferably 500-800 g/L.

5. The method according to any one of claims 1 to 4, wherein the molar ratio of the organic diacid in the aqueous solution containing the organic diacid to the organic diamine in the liquid-phase material containing the organic diamine is 1: 1.

6. The method according to any one of claims 1 to 5, wherein the reaction temperature is 30 to 220 ℃;

preferably, the residence time of the reaction is 0.5-60 min, preferably 3-5 min.

7. The method according to any one of claims 1 to 6, wherein the nylon salt solution is subjected to pH adjustment to obtain an adjusted nylon salt solution.

8. The method of claim 7, wherein the pH adjustment is in the range of 7.5 to 8;

preferably, the pH adjusting agent is an organic diamine or an organic diacid.

9. The method of any one of claims 1 to 8, wherein the nylon salt solution comprises any one of or a combination of at least two of a nylon 66 salt solution, a nylon 56 salt solution, a nylon 6T salt solution, a nylon 1010 salt solution, or a nylon 610 salt solution.

10. The method according to any one of claims 1 to 9, characterized in that it comprises: introducing an organic diacid-containing aqueous solution with the concentration of 0.01-1000 g/L and an organic diamine-containing liquid-phase material with the concentration of 0.01-1000 g/L into a microchannel reactor, wherein the molar ratio of the organic diacid in the organic diacid-containing aqueous solution to the organic diamine in the organic diamine-containing liquid-phase material is 1:1, reacting at 30-220 ℃, and keeping for 0.5-60 min, and adjusting the pH of the obtained nylon salt solution to 7.5-8 to obtain the adjusted nylon salt solution.

Technical Field

The invention relates to the technical field of material synthesis, in particular to a method for continuously synthesizing a nylon salt solution by using a microchannel reactor.

Background

Polyamide, commonly known as nylon, is an important engineering plastic variety, and has been widely used in automobiles, electronic and electrical appliances and other industrial and civil fields due to its excellent mechanical strength, heat resistance, chemical resistance and self-lubricity.

In the process of forming the salt of the nylon salt, the dibasic acid and the diamine with equal molar weight are mixed and then react to generate the nylon salt. With the progress of the reaction, the free diamine is gradually reduced until the salt-forming reaction is finished. If the diacid and the diamine are not uniformly mixed in the reaction process, the content of unreacted free diamine or diacid in the produced nylon salt product is too high, and the quality of the nylon salt is seriously influenced. In addition, because amine is unstable in air, side reaction is easy to occur when the amine is heated and meets oxygen, so that the quality of the nylon salt is deteriorated and the color of the nylon salt is yellow.

In the prior art, the nylon is mainly synthesized by the polycondensation reaction of dibasic acid and diamine, and in order to ensure the equimolar ratio of the dibasic acid and the diamine raw materials as much as possible, the dibasic acid and the diamine are usually prepared into nylon salt firstly, and then the polycondensation is carried out. Thus, as a precursor of nylon polymer, the product quality of nylon salt has a great influence on the quality of nylon polymer. Qualified nylon salt is a basic prerequisite for producing high-quality nylon polymers.

CN1887841A discloses a method for salifying by a solution method by using water as a solvent. In addition to water, an organic solvent such as ethanol or dimethylformamide may be used as a solvent for salt formation by the solution method.

CN101456804A discloses a method for salifying by a solution method by using N-methyl pyrrolidone or DMF as a solvent.

CN101880235A discloses a method for salifying by a solution method by using dimethyl sulfoxide as a solvent. Patent CN108285532A discloses a preparation method of nylon 65 salt, wherein it is mentioned that the nylon salt is synthesized by reacting for 1.5-5.0 h under the condition that the pH of the solution is controlled to be 7.20-7.90.

In summary, the existing nylon salt preparation methods all require a long time of reaction in a kettle to achieve balance, some require organic solvents, are difficult to completely isolate air, and cause diamine yellowing at high temperature, thereby affecting the final chromaticity and performance of products.

Therefore, it is required to develop a method for synthesizing a nylon salt solution which can be continuously salified and can prevent the diamine from yellowing.

Disclosure of Invention

In view of the problems in the prior art, the invention provides a method for continuously synthesizing a nylon salt solution by using a microchannel reactor, wherein the method can shorten the salt forming time to within 5min from the original 1.5-5.0 h by using the microchannel reactor under the better condition; and the salifying process is simple to operate, the micro-mixing efficiency is effectively improved, and the prepared nylon product has excellent chromaticity.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for continuously synthesizing a nylon salt solution by using a microchannel reactor, which comprises the following steps: and introducing the aqueous solution containing the organic diacid and the liquid-phase material containing the organic diamine into a microchannel reactor for reaction to obtain the nylon salt solution.

The invention utilizes the microchannel reactor to carry out reaction, can adopt aqueous solution as basic solution, does not need to adopt other solvents and other substances, is beneficial to realizing continuous production, obviously improves the uniform mixing degree of organic diacid and organic diamine, greatly shortens the salifying time, can effectively isolate oxygen, reduces the oxidation of diamine and improves the chromaticity of final products.

The organic diacid-containing aqueous solution is completely dissolved aqueous solution or uniformly mixed slurry, and the organic diamine-containing liquid phase material is completely dissolved aqueous solution, uniformly mixed slurry or liquid phase after melting.

Preferably, the organic diacid includes any one of adipic acid, terephthalic acid, glutaric acid, or sebacic acid, or a combination of at least two thereof, with typical but non-limiting combinations being adipic and terephthalic acid, adipic and glutaric acid, sebacic and terephthalic acid, and adipic and sebacic acid.

Preferably, the organic diamine comprises any one or a combination of at least two of hexamethylene diamine, pentamethylene diamine, p-phenylene diamine or decamethylene diamine, wherein typical but non-limiting combinations are the combination of hexamethylene diamine and pentamethylene diamine, the combination of p-phenylene diamine and pentamethylene diamine, the combination of decamethylene diamine and pentamethylene diamine, and the combination of hexamethylene diamine and decamethylene diamine.

Preferably, the concentration of the organic diacid in the organic diacid-containing aqueous solution is 0.01 to 1000g/L, for example, 0.01g/L, 1g/L, 112g/L, 223g/L, 334g/L, 445g/L, 556g/L, 667g/L, 778g/L, 889g/L or 1000g/L, and the like, but not limited to the recited values, and other values not recited in this range are also applicable, preferably 500 to 800 g/L.

Preferably, the concentration of the organic diamine in the liquid material containing the organic diamine is 0.01 to 1000g/L, for example, 0.01g/L, 1g/L, 112g/L, 223g/L, 334g/L, 445g/L, 556g/L, 667g/L, 778g/L, 889g/L or 1000g/L, etc., but not limited to the values listed, and other values not listed in the range are also applicable, preferably 500 to 800 g/L.

Preferably, the liquid-phase material containing the organic diamine is an aqueous solution containing the organic diamine or a molten liquid phase of the organic diamine.

Preferably, the molar ratio of the organic diacid in the aqueous solution containing the organic diacid to the organic diamine in the liquid-phase material containing the organic diamine is 1: 1.

Preferably, the reaction temperature is 30 to 220 ℃, for example, 30 ℃, 52 ℃, 73 ℃, 94 ℃, 115 ℃, 136 ℃, 157 ℃, 178 ℃, 199 ℃ or 220 ℃, but not limited to the cited values, and other values not listed in the range are also applicable.

Preferably, the residence time of the reaction is 0.5 to 60min, for example, 0.5min, 5min, 7min, 13min, 20min, 27min, 33min, 40min, 46min, 53min or 60min, etc., but not limited to the recited values, and other values not recited in this range are also applicable, preferably 3 to 5 min.

Preferably, the nylon salt solution is subjected to pH adjustment to obtain an adjusted nylon salt solution.

Preferably, the pH adjustment range is 7.5 to 8, and may be, for example, 7.5, 7.6, 7.7, 7.8, 7.9, 8, or the like, but is not limited to the values listed, and other values not listed in the range are also applicable.

Preferably, the pH adjusting agent is an organic diamine or an organic diacid.

Preferably, the nylon salt solution comprises any one of or a combination of at least two of a nylon 66 salt solution, a nylon 56 salt solution, a nylon 6T salt solution, a nylon 1010 salt solution, or a nylon 610 salt solution, wherein typical but non-limiting combinations are a combination of a nylon 66 salt solution and a nylon 56 salt solution, a combination of a nylon 66 salt solution and a nylon 6T salt solution, a combination of a nylon 6T salt solution and a nylon 1010 salt solution, and a combination of a nylon 66 salt solution and a nylon 1010 salt solution.

As a preferred technical solution of the present invention, the method comprises: introducing an organic diacid-containing aqueous solution with the concentration of 0.01-1000 g/L and an organic diamine-containing liquid-phase material with the concentration of 0.01-1000 g/L into a microchannel reactor, wherein the molar ratio of the organic diacid in the organic diacid-containing aqueous solution to the organic diamine in the organic diamine-containing liquid-phase material is 1:1, reacting at 30-220 ℃, and keeping for 0.5-60 min, and adjusting the pH of the obtained nylon solution to 7.5-8 to obtain an adjusted nylon salt solution.

Preferably, an auxiliary agent is also added in the pH adjusting process.

The addition of any auxiliary agent which can be used for preparing nylon and is well known to those skilled in the art can be adopted, and the addition can be adjusted according to a special process.

The specific method for preparing the nylon product by the subsequent preparation of the adjusted nylon solution is not particularly limited, and the method for preparing the nylon product, which is well known to those skilled in the art, can be adopted, and the modified method for preparing the nylon product can also be adopted.

Preferably, the method for preparing the nylon product by using the adjusted nylon solution prepared by the invention comprises the following steps: the adjusted nylon 66 salt solution is sequentially adsorbed by activated carbon and filtered by a filter membrane, and then is sent into a nylon synthesis device, the temperature is raised to 200-220 ℃ to remove water in the system until the concentration of nylon salt in the system is 70-80%, the temperature is continuously raised to 260-300 ℃, and the temperature and pressure are maintained for 1-2 hours to carry out prepolymerization reaction on the nylon salt; and after the prepolymerization reaction is finished, removing residual bubbles in the system under negative pressure, finishing the reaction, and forming to obtain the nylon product.

The invention is further preferably carried out by adopting the conventional method, and is easy for industrial production.

The device adopted by the method of the invention is not particularly limited as long as the process flow of the invention can be realized.

Compared with the prior art, the invention has at least the following beneficial effects:

(1) according to the method for continuously synthesizing the nylon salt solution by using the microchannel reactor, reaction raw materials can be quickly reacted and uniformly mixed in the plate of the microchannel reactor, byproducts are few, and the chromaticity of a final nylon product is improved;

(2) the method for continuously synthesizing the nylon salt solution by the microchannel reactor shortens the salt forming time to within 60min from the original 1.5-5.0 h, can shorten the salt forming time to within 5min under the optimal condition and simultaneously achieves the effect of the yellow index of below 0, and has the advantages of simple operation and high micro mixing efficiency in the salt forming process.

Drawings

Fig. 1 is an apparatus for a method of synthesizing nylon according to an embodiment of the present invention.

In the figure: 11-an organic diamine mixing device; 12-an organic diacid mixing device; 2-microchannel reactor; 31-a first pH adjusting device; 32-a second pH adjustment device; 4-an activated carbon adsorption device; 5-a filtration membrane device; 6-nylon synthesizer.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

The invention provides a method for continuously synthesizing a nylon salt solution by using a microchannel reactor, which comprises the following steps: introducing an organic diacid-containing aqueous solution with the concentration of 0.01-1000 g/L and an organic diamine-containing liquid-phase material with the concentration of 0.01-1000 g/L into a microchannel reactor, wherein the molar ratio of the organic diacid in the organic diacid-containing aqueous solution to the organic diamine in the organic diamine-containing liquid-phase material is 1:1, reacting at 30-220 ℃, and keeping for 0.5-60 min, and adjusting the pH of the obtained nylon solution to 7.5-8 to obtain an adjusted nylon salt solution.

The process flow of the present invention for preparing the nylon product is not particularly limited, and any process flow and process parameters known to those skilled in the art for converting a nylon salt solution into a nylon product can be used. Preferably, the method for preparing the nylon product by using the adjusted nylon solution prepared by the invention comprises the following steps: the adjusted nylon 66 salt solution is sequentially adsorbed by activated carbon and filtered by a filter membrane, and then is sent into a nylon synthesis device, the temperature is raised to 200-220 ℃ to remove water in the system until the concentration of nylon salt in the system is 70-80%, the temperature is continuously raised to 260-300 ℃, and the temperature and pressure are maintained for 1-2 hours to carry out prepolymerization reaction on the nylon salt; and after the prepolymerization reaction is finished, removing residual bubbles in the system under negative pressure, finishing the reaction, and forming to obtain the nylon product.

The specific embodiment part provides a device for synthesizing nylon, and the device adopted by the method is shown in figure 1, and specifically comprises a microchannel reactor 2 and a pH adjusting device which are connected in sequence, wherein the pH adjusting device comprises a first pH adjusting device 31 and a second pH adjusting device 32; an organic diacid mixing device 12 and an organic diamine mixing device 11 are arranged in front of the microchannel reactor 2; an activated carbon adsorption device 4, a filtering membrane device 5 and a nylon synthesis device 6 which are connected in sequence are arranged behind the pH adjusting device; and the pH adjusting device is provided with an organic diacid feeding device, an organic diamine feeding device and an auxiliary agent feeding device.

The following will explain in detail by taking specific examples as examples.

The following examples are presented by way of example of a nylon 66 salt solution for comparison purposes, and the process of the present invention is applicable to other similar nylon salt solutions.

Example 1

This embodiment provides a method for synthesizing nylon, which is performed by using the method for continuously synthesizing a nylon salt solution by using a microchannel reactor according to the present invention, and is performed by using the apparatus in fig. 1, and specifically includes the following steps:

synthesis of nylon salt solution: preparing 10% aqueous solution from 100g of adipic acid and 900g of deionized water, and heating until the solution is completely dissolved to obtain 100g/L aqueous solution containing adipic acid; preparing 90% aqueous solution from 900g of hexamethylenediamine and 100g of deionized water to obtain 100g/L aqueous solution containing hexamethylenediamine; the two streams were mixed as n (adipic acid): pumping n (hexamethylene diamine) into a microchannel reactor with the ratio of 1:1, and controlling the reaction temperature to be 70 ℃; controlling the flow rate of the materials by reaction, and keeping the reaction time for 2 min; after the reaction process is completed, the effluent leaving the reaction zone is the nylon 66 salt solution. And (3) feeding the nylon 66 salt solution into a first pH adjusting device or a second pH adjusting device, adjusting the pH to about 7.6 by using hexamethylene diamine or adipic acid, and adding a catalyst (mainly Lewis acid) to obtain the adjusted nylon 66 salt solution.

Preparation of nylon products: the adjusted nylon 66 salt solution is sequentially sent into an activated carbon adsorption device and a filtering membrane device, is subjected to activated carbon adsorption and filtering by a filtering membrane, and is sent into a nylon synthesis device, the temperature is raised to 210 ℃ to remove water in the system until the concentration of nylon salt in the system is 75%, the temperature is continuously raised to 270 ℃, and the temperature and pressure are maintained for 1.5h to carry out prepolymerization reaction on the nylon salt; and after the prepolymerization reaction is finished, removing residual bubbles in the system under negative pressure, finishing the reaction, and pulling strips and cutting into granules to obtain the nylon product.

Example 2

The embodiment provides a method for continuously synthesizing a nylon salt solution by using a microchannel reactor, which specifically comprises the following steps:

preparing 50% aqueous solution from 500g of adipic acid and 500g of deionized water, and heating until the adipic acid and the deionized water are completely dissolved to obtain 500g/L aqueous solution containing the adipic acid; preparing 50% aqueous solution from 500g of hexamethylenediamine and 500g of deionized water to obtain 500g/L aqueous solution containing hexamethylenediamine; the two streams were mixed as n (adipic acid): pumping n (hexamethylene diamine) into a microchannel reactor with the ratio of 1:1, and controlling the reaction temperature to be 60 ℃; controlling the flow rate of the materials by reaction, and keeping the reaction time for 5 min; after the reaction process is completed, the effluent leaving the reaction zone is the nylon 66 salt solution.

Feeding the nylon 66 salt solution into a first pH adjusting device or a second pH adjusting device, adjusting the pH to about 8 by using hexamethylene diamine or adipic acid, and adding a catalyst to obtain an adjusted nylon 66 salt solution;

example 3

The embodiment provides a method for continuously synthesizing a nylon salt solution by using a microchannel reactor, which specifically comprises the following steps:

preparing 25% aqueous solution from 250g of adipic acid and 750g of deionized water, and heating until the adipic acid and the deionized water are completely dissolved to obtain 250g/L aqueous solution containing the adipic acid; heating and melting hexamethylene diamine to obtain a liquid-phase material; the two streams were mixed as n (adipic acid): pumping n (hexamethylene diamine) which is 1:1 into a microchannel reactor, and controlling the reaction temperature to be 90 ℃; controlling the flow rate of the materials by reaction, and keeping the reaction time for 2 min; after the reaction process is completed, the effluent leaving the reaction zone is the nylon 66 salt solution.

And (3) feeding the nylon 66 salt solution into a first pH adjusting device or a second pH adjusting device, adjusting the pH to about 7.5 by using hexamethylene diamine or adipic acid, and adding a catalyst to obtain the adjusted nylon 66 salt solution.

Example 4

This example provides a method for continuously synthesizing nylon salt solution by using a microchannel reactor, which is different from example 3 only in that the reaction temperature in the microchannel reactor is controlled to 220 ℃.

Example 5

This example provides a continuous synthesis of nylon salt solution in a microchannel reactor, which differs from example 3 only in that the residence time in the microchannel reactor is controlled to 5 min.

Example 6

This example provides a continuous synthesis of nylon salt solution in a microchannel reactor, which differs from example 3 only in that the residence time in the microchannel reactor is controlled to 60 min.

Example 7

This example provides a continuous synthesis of nylon salt solution in microchannel reactor, which differs from example 2 only in that the concentration of the adipic acid-containing aqueous solution is 800g/L and the concentration of the hexamethylenediamine-containing aqueous solution is 800 g/L.

Example 8

This example provides a continuous synthesis of nylon salt solution in a microchannel reactor, which differs from example 2 only in the replacement of adipic acid with glutaric acid.

Comparative example 1

This comparative example provides a method of synthesizing a nylon salt solution using the method of preparation of the nylon 65 salt of example 1 in CN 108285532A.

The comparative example is carried out by adopting a stirring reaction and distillation mode, so that the yellow index of the finally obtained nylon product is obviously higher than that of the nylon products of examples 1-8

Comparative example 2

This comparative example provides a process for synthesizing a nylon salt solution that maintained a residence time of 5min, except that the microchannel reactor of example 2 was replaced with a stirred tank reactor.

Comparative example 3

This comparative example provides a process for synthesizing a nylon salt solution which is the same as comparative example 2 except that the residence time of 5min in comparative example 2 was replaced with 90 min.

Comparative example 4

This comparative example provides a process for synthesizing a nylon salt solution which was the same as that of example 2 except that the adipic acid-containing aqueous solution in example 1 was replaced with an adipic acid-containing N-methylpyrrolidone solution and the hexamethylenediamine-containing aqueous solution was replaced with an hexamethylenediamine-containing N-methylpyrrolidone solution.

The steps for converting the nylon salt into the nylon product in the above-mentioned other examples and comparative examples were carried out by referring to the steps in example 1, and the yellowness index of the final nylon product was measured by using the HG/T3862 method.

The test results of the above examples and comparative examples are shown in table 1.

TABLE 1

	Yellowness index of Nylon products
		Example 1	-1.5
Example 2	-2.2
		Example 3	-1.5
Example 4	-2.1
		Example 5	-2.0
Example 6	-1.1
		Example 7	-1.2
Example 8	-1.5
		Comparative example 2	10.2
Comparative example 3	11.5
		Comparative example 4	5.1

From table 1, the following points can be seen:

(1) it can be seen from the comprehensive examples 1 to 8 that the nylon prepared by using the microchannel reactor has lower product yellow index, better product quality and shorter time consumption, the synthesis time in examples 1 to 8 can reach the effect of the yellow index below-1.0 within 60min, the synthesis time is within 5min under the optimal conditions, and the yellow index of the nylon product is below-2.0;

(2) it can be seen from the comprehensive examples 1 and comparative examples 2 to 3 that the microchannel reactor is selected to continuously synthesize the nylon salt solution in example 1, compared with the stirred reaction kettle adopted in comparative examples 2 to 3, the synthesis time in example 1 is only 5min, and the yellow index of the final nylon product is only-1.5, while the yellow index of the product in comparative example 2 is 10.2 at the same time, which indicates that the continuous synthesis of the nylon salt solution by the microchannel reactor significantly shortens the reaction time and improves the chromaticity of the nylon product.

In conclusion, the method for continuously synthesizing the nylon salt solution by using the microchannel reactor has the advantages of short reaction time, high reaction efficiency, strong operability, high safety and easiness in industrial production by using the microchannel reactor to synthesize the nylon salt, and the prepared nylon product has excellent chromaticity and wide application prospect.

Probably because the process does not contact with air, and the retention time is shorter, the oxidation of the product is effectively reduced.

The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.