CN111592457B - Long-chain dibasic acid with concentrated particle size distribution and preparation method thereof - Google Patents
Long-chain dibasic acid with concentrated particle size distribution and preparation method thereof Download PDFInfo
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Abstract
The invention provides a method for controlling the granularity of long-chain dibasic acid and the long-chain dibasic acid with concentrated granularity distribution prepared by the method. The method improves the particle uniformity of the long-chain binary acid product, has few fine particles, improves the product quality, avoids the trouble of re-granulating the product, saves the production cost, saves time and is efficient, and suitable for industrial application.
Description
Technical Field
The invention belongs to the technical field of industrial crystallization, and particularly relates to a long-chain dibasic acid with concentrated particle size distribution and a preparation method thereof.
Background
The long chain dibasic acid is linear aliphatic dibasic acid with carbon chain containing more than 10 carbon atoms, is a basic monomer material of a series of special synthetic materials, can be used for producing special nylon, polycarbonate, powder coating, spice, hot melt adhesive, special lubricant and the like, and is an important raw material of products such as synthetic spice, engineering plastic, cold-resistant plasticizer, high-grade lubricating oil, polyamide hot melt adhesive, powder coating and the like.
Long chain dibasic acids are not present in nature and certain kinds of long chain dibasic acids, such as sebacic acid and dodecanedioic acid, can be chemically synthesized. In addition, long chain dibasic acids may also be produced by biological methods. The biological method production is the application of the microorganism fermentation technology which is raised in the 70 s in the petrochemical field, and is widely paid attention to at home and abroad. Biological methods can provide a range of long carbon chain diacid monomers from C9 to C18. After preliminary pretreatment, separation and purification, the long-chain dibasic acid fermentation broth produced by the biological fermentation method must be recrystallized to obtain a finished product with a certain particle size distribution and crystal shape. Crystallization can perform purification and product separation simultaneously, and in addition, crystallization also provides the opportunity to control the particle size and shape distribution of the product and directly affect product performance and subsequent process efficiency.
Whether chemical or biological, the existing patents focus on the purity, pigment content, thermal stability and other indexes of the dibasic acid in terms of separation and purification of the dibasic acid, for example, the content of monocarboxylic acid in the dodeca-dibasic acid is required to be low, because the existence of monocarboxylic acid can play a role in stopping polymerization; the content of substances such as pigment which are easy to develop at high temperature is also required to be low, otherwise, the color and the performance of nylon are affected; as a raw material for synthesizing the perfume, the presence of hetero acids and impurities in trideceth can affect the fragrance of the perfume. However, to date, little attention has been paid to the granularity of the long chain dibasic acid isolation and purification product. The particle size distribution directly affects the process efficiency of downstream separation operations such as filtration or centrifugation, drying and the like, for example, the product particles are unevenly distributed and have very large particles, and simultaneously a plurality of fine particles exist, so that the fine particles are easy to be embedded into gaps among the large particles in the filtration process to block a filtrate channel, thereby causing difficult filtration, prolonging the operation period and increasing the energy consumption; the particles with uniform particle size distribution are more beneficial in the operation process of the filtering unit, so that the filtering time can be reduced, the operation period can be shortened, a large amount of energy consumption can be saved, and the production cost can be reduced. Similarly, the particle size distribution is also an important index of the performance of the product, such as uniform particle size, so that better product fluidity can be realized, the subsequent trouble of the product reconstruction process is avoided, and the production cost is saved.
Disclosure of Invention
Aiming at the defect that the prior art does not relate to the particle size distribution of long-chain dibasic acid separation and purification products, the invention aims to provide long-chain dibasic acid with concentrated particle size distribution and an effective preparation method thereof, and the particle size of the products can be controlled within a certain range without grinding and screening processes.
In order to achieve the above object, according to an aspect of the present invention, there is provided a long-chain dibasic acid having a concentrated particle size distribution, the long-chain dibasic acid having an average particle diameter of 250 to 450 μm, more preferably 250 to 430 μm, and/or,
10% cumulative volume particle size D 10 A cumulative volume particle size D of 100 to 250. Mu.m, preferably 10% 10 100 to 230 μm, and/or,
50% cumulative volume particle size D 50 A cumulative volume particle size D of 250 to 450. Mu.m, preferably 50% 50 250 to 440 um, and/or,
90% cumulative volume particle size D 90 A cumulative volume particle size D of 350 to 600. Mu.m, preferably 90% 90 370 to 590 μm, and/or,
the coefficient of variation c.v. is 30% to 40%, more preferably 30% to 36%, and/or,
the purity reaches more than 99.6 percent.
On the other hand, the invention provides a method for preparing the long-chain dibasic acid with concentrated particle size distribution, and the long-chain dibasic acid with concentrated particle size distribution, which has better particle dispersibility and better fluidity, is obtained by adopting the method, so that the problems of poor centrifugal efficiency, long drying process time, excessive dust and caking in the transportation process and the like can be solved, and the subsequent trouble of the product re-granulation process is avoided.
Specifically, the method for preparing the long-chain dibasic acid with concentrated particle size distribution comprises the following steps:
A. dissolving long-chain dibasic acid and/or mixture comprising long-chain dibasic acid in organic solvent,
B. the following steps are repeated in a cyclic manner:
b-1: cooling to a temperature T 2M When particles are separated out from the solution, the solution is kept at the temperature for a period of time U 2M Or directly carrying out the next step;
b-2: heating to a temperature T 3M The number of particles in the solution is reduced, and the solution is kept at the temperature for a period of time U 3M Or directly carrying out the next step;
m represents the Mth cycle, M is an integer greater than or equal to 1;
and the temperature T of the Mth cycle 2M Temperature T of M+1st cycle 2(M+1) ；
Temperature T of the Mth cycle 3M Temperature T of M+1st cycle 3(M+1) 。
The number of times N of the repeated circulation step B can be determined according to the granularity dispersity of the long-chain binary acid product, preferably, the number of times N of the repeated circulation step B is 1-20 times, and more preferably, the number of times N of the repeated circulation step B is 2-15 times.
The long-chain dibasic acid is saturated or unsaturated linear dibasic acid with 10-18 carbon atoms and carboxyl at two ends of a carbon chain, and can be a mixture of any two or more of the dibasic acids; preferably, the long chain diacid is selected from one or more of sebacic acid, undecanedioic acid, dodecadioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanodioic acid, hexadecanedioic acid, heptadecanodioic acid, octadecanedioic acid, and 9-ene-octadecanedioic acid.
The long-chain dibasic acid may be of any purity, for example, may be a crude product containing impurities, or may be a long-chain dibasic acid of a purity of not less than 95 wt.%.
The organic solvent is selected from alcohols, monoacids and mixtures of two or more thereof; preferably, the organic solvent is selected from acetic acid, acetic acid C 1 -C 6 Alcohol esters, C 1 -C 6 Alcohols, and mixtures of two or more thereof. Examples of the organic solvent include, but are not limited to: acetic acid, ethanol, n-propanol, isopropanol, 2-butanol, ethyl acetate; further preferably, the organic solvent is an acetic acid solution having a content of 90wt.% or more.
The weight ratio of the long-chain dibasic acid to the organic solvent is 1: (1.5-6), more preferably 1: (2-5), for example, the weight ratio of the long-chain dibasic acid to the organic solvent is 1:1.8, 1:2.3, 1:2.7, 1:2.9, 1:3.1 or 1:4.1.
in some preferred embodiments of the invention, in step a, the dissolving comprises the steps of: mixing the long-chain dibasic acid and/or the mixture comprising the long-chain dibasic acid with an organic solvent, and regulating the temperature of the system to T 1 Dissolving;
preferably, when the mixture including long-chain dibasic acid is a crude long-chain dibasic acid, the step is performed after the dissolution, decolorization, filtration and the like;
Preferably, the temperature of the system is regulated to T 1 Hold time U 1 Dissolving.
In a preferred embodiment of the invention, the temperature T 1 1-40 ℃ higher than the precipitation temperature of the long-chain dibasic acid in the solution, preferably the temperature T 1 10 to 20 ℃ higher than the precipitation temperature of the long-chain dibasic acid in the solution, e.g. the temperature T 1 The precipitation temperature of the long-chain dibasic acid in the solution is 5 ℃, 8 ℃, 13 ℃, 17 ℃, 23 ℃, 28 ℃, 32 ℃ or 37 ℃ higher than that of the long-chain dibasic acid.
The precipitation temperature of the long-chain dibasic acid in the solution refers to the temperature at which the long-chain dibasic acid starts to precipitate in the solution, and can be measured by a person skilled in the art according to the prior art.
In a preferred embodiment of the invention, the temperature T 1 Selected from 50 to 130 ℃, preferably 70 to 110 ℃, e.g. temperature T 1 53 ℃, 58 ℃, 63 ℃, 68 ℃, 73 ℃, 78 ℃, or 83 ℃.
Said temperature T 2M Below said temperature T 1 Preferably, the temperature T 2M Selected from 30 to 90℃and more preferably 30 to 80 ℃.
Said temperature T 3M Below said temperature T 1 And is higher than the temperature T 2M Preferably, the temperature T 3M Than said temperature T 1 Lower by 5-100 ℃ than the temperature T 2M Higher by 1 to 10 ℃, more preferably, the temperature T 3M Than said temperature T 1 Lower by 10-80 ℃ than the temperature T 2M The temperature is 1-8 ℃.
Further preferably, the temperature T 3M Selected from 30 to 100 ℃, preferably 30 to 80 ℃.
In a preferred embodiment of the invention, the time U 1 Time U 2M Time U 3M By the skilled man, a reasonable choice can be made according to the amount of raw materials, the kind of solvent, etc., preferably the time U 1 About 0.5 to 2 hours, more preferably about 0.5 to 1 hour; said time U 2M About 0 to 2 hours, more preferably about 0 to 1 hour; said time U 3M About 0 to 2 hours, and more preferably about 0 to 1 hour.
In a preferred embodiment of the present invention, in the step B-1, the cooling rate is 0.5 to 10 min/DEG C, more preferably 1 to 5 min/DEG C, and particularly preferably 2 to 4 min/DEG C.
In a preferred embodiment of the present invention, in the step B-2, the temperature is raised at a rate of 0.5 to 10 min/DEG C, more preferably 1 to 5 min/DEG C, and particularly preferably 2 to 4 min/DEG C.
In a preferred embodiment of the present invention, the temperature is lowered in the step B-1 at a slower rate than the temperature is raised in the step B-2, preferably, the temperature is lowered in the step B-1 at a slower rate than the temperature is raised in the step B-2 by 1 to 5 min/. Degree.C.
In a preferred embodiment of the present invention, among the N cycles, the two cycles sequentially performed are consecutive two cycles, for example, the mth cycle performed first and the (m+1) th cycle performed later, which are consecutive two cycles. Wherein M is an integer of 1 or more and 1 or less (N-1), preferably 1 to 19, and more preferably 1 to 14. Specifically, the 2 nd cycle and the 3 rd cycle are two consecutive cycles, the 2 nd cycle is the M th cycle, and the 3 rd cycle is the m+1th cycle.
In a preferred embodiment of the invention, the temperature T in the Mth cycle 2M And temperature T of the M+1st cycle 2(M+1) The difference between them is 0 to 15℃and preferably 0 to 10 ℃.
In a preferred embodiment of the invention, the temperature T in the Mth cycle 3M And temperature T of the M+1st cycle 3(M+1) The difference between them is 0 to 15℃and preferably 0 to 10 ℃.
In a preferred embodiment of the present invention, the cooling rate in the mth cycle is the same as the cooling rate in the m+1th cycle.
In a preferred embodiment of the present invention, the cooling rate in the mth cycle is different from the cooling rate in the m+1th cycle, for example, the cooling rate in the mth cycle is 1-5 min/°c faster than the cooling rate in the m+1th cycle, or the cooling rate in the mth cycle is 1-5 min/°c slower than the cooling rate in the m+1th cycle.
In a preferred embodiment of the present invention, the temperature rise rate in the Mth cycle is the same as the temperature rise rate in the M+1th cycle.
In a preferred embodiment of the present invention, the temperature rising rate in the Mth cycle is different from the temperature rising rate in the M+1th cycle, for example, the temperature rising rate in the Mth cycle is 1-5 min/DEG C faster than the temperature rising rate in the M+1th cycle, or the temperature rising rate in the Mth cycle is 1-5 min/DEG C slower than the temperature rising rate in the M+1th cycle.
In a preferred embodiment of the present invention, when the long-chain dibasic acid is a crude long-chain dibasic acid, the decolorization is performed by a conventional decolorizing agent for removing a dyeing group in step a of the preparation method, for example, activated carbon, clay or an adsorption resin, but other decolorizing agents may be used. Preferably, the decolorizing agent is activated carbon. The amount of decolorizing agent used depends on the amount of leachables that may be present in the reaction mixture and the type of decolorizing agent. One skilled in the art can readily determine the appropriate minimum amount of decolorizing agent to be added to decolorize the mixture. In a preferred embodiment of the present invention, the decolorizing agent is activated carbon added in an amount of about 0.5 to 10wt.% based on the mass of the crude long chain dibasic acid.
The inventor has found after intensive research that the crystallization process of cooling down long-chain dibasic acid is changed into the crystallization process of temperature circulation control of heating up and cooling down, and the dissolution is carried out preferentially by utilizing that fine particles have larger specific surface area than larger particles in the heating up process. The supersaturation degree generated by the dissolved part of fine particles in the cooling process is reflected on the principle that the surface of larger particles continuously grows, and long-chain diacid products with few fine particles, more uniform particle size distribution and better fluidity are finally obtained through the circulation of cooling and heating for many times, and meanwhile, the process efficiency of downstream separation operation of crystallization is obviously improved.
In a preferred embodiment of the present invention, the above method for preparing long chain dibasic acid having concentrated particle size distribution further comprises, after repeating the nth cycle, adjusting to a temperature T 4 Holding time U at this temperature 4 Or directly to the next step.
In a preferred embodiment of the invention, the temperature T 4 The temperature is close to normal temperature, such as 15 to 35 ℃, preferably 20 to 35 ℃, more preferably 25 to 35 ℃, particularly preferably 30 to 35 ℃; and/or the number of the groups of groups,
said time U 4 About 0 to 2 hours, more preferably about 0 to 1 hour; and/or the number of the groups of groups,
the temperature is regulated to be lowered or raised, the temperature lowering speed is 0.5-10 min/DEG C, more preferably 1-5 min/DEG C, particularly preferably 2-4 min/DEG C, and the temperature raising speed is 0.5-10 min/DEG C, more preferably 1-5 min/DEG C, particularly preferably 2-4 min/DEG C.
In a preferred embodiment of the present invention, the method for preparing long chain dibasic acid with concentrated particle size distribution further comprises,
E. separating, washing and drying to obtain the long-chain dibasic acid finished product with concentrated particle size distribution.
The separation may be any solid-liquid separation method, for example, centrifugation, filtration, etc.
The washing can be performed by using an organic solvent or water, wherein the organic solvent is common ester solvents, alcohol solvents and alkane solvents, such as ethyl acetate, ethanol and cyclohexane.
The drying may be any drying method, for example, infrared drying, spray drying, etc., and the temperature in the drying process is preferably controlled to 95 to 120 ℃, more preferably 100 to 110 ℃, particularly preferably 105 ℃.
Compared with the prior art, the method has the following advantages and characteristics:
1. effectively controlling the granularity of long-chain binary acid products, the average grain diameter is 250-450 mu m, D 10 Is 100-250 mu m, D 50 250-450 mu m, D 90 The variation coefficient C.V. is 30-40% and the purity is over 99.6% with the value of 350-600 μm.
2. The product particles are uniform, few fine particles are adopted, the product quality is improved, the subsequent process performance is improved, the filtering performance is very good, the production efficiency is improved, the operation period is shortened, the energy consumption is reduced, and the production cost is greatly reduced.
3. The fluidity of long-chain binary acid products is improved, the problem of product transportation agglomeration is solved, the trouble of subsequent re-granulation of the products is avoided, and the production cost is saved.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The term "about" refers to the degree of inherent uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term "quantitative" as used herein refers to a value expressed as a deviation from the stated reference value without resulting in a change in the basic function of the subject matter at issue.
1. Purity testing method and apparatus:
the sample is subjected to pretreatment and then gas chromatography detection (normalization method), and chromatographic conditions are as follows: chromatographic column: supelco SPB-50 30m*0.53mm*0.5 μm (cat# 54983).
Gas chromatograph (Shimadzu, GC-2014).
The method comprises the following steps: the initial temperature is 100 ℃, the temperature is increased to 230 ℃ at 15 ℃/min, and the temperature is kept for 2min. The carrier gas is hydrogen, the temperature of the sample inlet is 280 ℃, the temperature of the FID is 280 ℃, and the sample feeding amount is 4 mu L.
And calculating the purity and impurity content of the product according to the peak area of the product and the peak area of the impurity.
2. Particle size evaluation method and device:
90% cumulative volume particle size D according to the invention 90 50% cumulative volume particle size D 50 And 10% cumulative volume particle size D 10 Is a typical quantity for indicating the particle size distribution.
Said 90% cumulative volume particle size D 90 Is a value for the particle size such that 90vo1.% crystals have a size below this value.
Said 50% cumulative volume particle size D 50 Is a value for the particle size such that 50vol.% of the crystals have a size less than this value.
The 10% cumulative volume particle size D 10 Is a value for the particle size such that 10vo1.% crystals have a size below this value.
Particle size was assessed using a Focused Beam Reflectance Measurement (FBRM) instrument, model partiletrack G400, available from METTLER TOLEDO (METTLER toldo). Obtaining D by using FBRM through particle chord length distribution statistics in a certain area in laser reflection measurement system 10 、D 16 、D 50 、D 84 、D 90 And (3) data and calculating a variation coefficient (C.V.) value reflecting the degree of dispersion of the particle size distribution.
The standard deviation SD of the volume-based particle size distribution shown in the following formula (1),
SD＝(D 84 -D 16 )/2 (1)
in the formula (1), D 84 Particle diameter D representing the point at which the volume accumulation curve reaches 84% 16 The particle diameter at the point where the volume accumulation curve reaches 16% is shown.
Particle diameter D 50 And the standard deviation SD represents the degree of smoothness of the particle size distribution in absolute value.
Further, from the viewpoint of the relationship between the gentle particle size distribution and the particle diameter, the coefficient of variation c.v. of the volume-based particle size distribution is represented by the following formula (2).
C.V.＝(SD/D 50 )×100 (2)
The coefficient of variation c.v. indicates the degree of smoothness with respect to particle size.
3. The crude undecanedioic acid and the crude dodecaanedioic acid are prepared according to CN200410018255.7 and are further purified by a CN201010160266.4 method. In the following examples, the starting undecanedioic acid had a purity of 99.1% and an average particle diameter of 231. Mu.m, D 10 ＝155μm，D 50 ＝331μm，D 90 ＝642μm，D 16 ＝179μm，D 84 577 μm, coefficient of variation c.v. = 60.11%; raw material dodecadiacid crude product purity is 95%, average grain diameter is 319 μm, D 10 ＝139μm，D 50 ＝316μm，D 90 ＝748μm，D 16 ＝175μm，D 84 =674 μm, coefficient of variation c.v. = 79.10%; the purity of the raw material dodecadiacid is 99 percent, the average grain diameter is 203 mu m, D 10 ＝120μm，D 50 ＝206μm，D 90 ＝381μm，D 16 ＝142μm，D 84 =359 μm, coefficient of variation c.v. =52.50%.
4. Total nitrogen determination:
the Kjeldahl method is adopted.
5. Light transmittance measurement:
a long chain dibasic acid sample was dissolved into 5wt.% aqueous sodium salt solution, and then UV-detected for light transmittance at 430 nm.
6. Measurement of moisture:
the Karl Fischer method is adopted, and the moisture content in the sample is tested by a 870Titrino plus practical capacity method Karl Fischer moisture tester of the Switzerland.
Example 1
Placing the crude product of the dodecadiacid (the purity is 95%) in a decoloring tank, adding active carbon with the mass of 3.5% of the crude product of the dodecadiacid and acetic acid with the mass of 95wt.% into which the mass ratio of the acetic acid with the mass of 95wt.% is 3:1 after being converted into the acetic acid with the mass of 100wt.% to the crude product of the dodecadiacid, decoloring for 20min at 80 ℃, and filtering to obtain the dodecadiacid solution. In a crystallizer, the dodecadibasic acid solution was kept at a constant temperature of 80℃for 1 hour.
Cooling to 60deg.C at the rate of 2 min/deg.C, and separating out the particles in the solution and increasing the particle number. Heating to 67 ℃ at the rate of 3 min/DEG C, continuously reducing the particle number in the solution, and ending the first temperature cycle; the second temperature cycle, cooling to 52 ℃ at the rate of 2 min/DEG C, and then heating to 59 ℃ at the rate of 3 min/DEG C; the third temperature cycle is carried out, after the temperature is reduced to 44 ℃ at the rate of 2 min/DEG C, the temperature is increased to 51 ℃ at the rate of 3 min/DEG C; fourth temperature circulation, cooling to 36 ℃ at the rate of 2 min/DEG C, and then heating to 43 ℃ at the rate of 3 min/DEG C; and (3) after the fifth temperature cycle is carried out and the temperature is reduced to 28 ℃ at the rate of 2 min/DEG C, the temperature is increased to 35 ℃ at the rate of 3 min/DEG C, and the temperature is kept for 0.5h. After five temperature cycles, filtering, washing with one time of water (relative to the weight of the long-chain dicarboxylic acid crude product), and drying at 105 ℃ for 1 hour in a paddle dryer to obtain the final product of the dodecadiacid.
The purity of the dodecadiacid finished product is 99.73 percent, and the purity of the product is qualified; average particle diameter of 319 μm, D 10 ＝195μm，D 50 ＝311μm，D 90 ＝452μm，D 16 ＝218μm，D 84 The product particles have a low degree of dispersion and a uniform distribution, with a variation coefficient c.v. =31.99%, with 417 μm.
Comparative example 1
The dodecadibasic acid solution was prepared as in example 1, and the prepared dodecadibasic acid solution was kept at a constant temperature of 80℃for 1 hour in a crystallizer. Cooling to 74 ℃ at the rate of 5 min/DEG C, wherein a small amount of particles are precipitated in the solution and gradually increase, and keeping the temperature for 1h. Cooling to 64 ℃ at the rate of 10 min/DEG C, cooling to 54 ℃ at the rate of 8 min/DEG C, cooling to 44 ℃ at the rate of 6 min/DEG C, cooling to 34 ℃ at the rate of 5 min/DEG C, keeping the temperature constant for 0.5h at the temperature, filtering, washing with one time of water (relative to the weight of the crude long-chain dibasic acid), and drying at 105 ℃ for 2 hours in a paddle dryer to obtain the final product of the dodecadiacid.
The final product of dodecadiacid had a purity of 98.36% and was obtained by the method of example 1The purity of the dodecandioic acid product is lower; average particle diameter of 319 μm, D 10 ＝139μm，D 50 ＝286μm，
D 90 ＝548μm，D 16 ＝165μm，D 84 =474 μm, coefficient of variation c.v. =54.02%, which is a product with a very discrete particle distribution and a non-uniform distribution.
Comparative example 2
The dodecadibasic acid solution was prepared as in example 1, and the prepared dodecadibasic acid solution was kept at a constant temperature of 80℃for 1 hour in a crystallizer. Cooling to 74 ℃ at the rate of 5 min/DEG C, taking the dodecadiacid crystal as a seed crystal, adding 1wt.% of seed crystal (taking the dodecadiacid crude product as a reference), precipitating a large amount of particles in the solution, and keeping the temperature for 1h. Cooling to 64 ℃ at the rate of 10 min/DEG C, cooling to 54 ℃ at the rate of 8 min/DEG C, cooling to 44 ℃ at the rate of 6 min/DEG C, cooling to 34 ℃ at the rate of 5 min/DEG C, keeping the temperature constant for 0.5h, finally filtering, washing with one time of water (relative to the weight of the crude long-chain dibasic acid), and drying at 105 ℃ for 2 hours in a paddle dryer to obtain the final product of the dodecadiacid.
The product has purity of 99.45%, average particle diameter of 273 μm, and D 10 ＝120μm，D 50 ＝246μm，D 90 ＝461μm，D 16 ＝142μm，D 84 The product particles were distributed to a large degree of dispersion and non-uniform in distribution with a coefficient of variation c.v=53.66=406 μm.
Comparative example 3
The dodecadibasic acid solution was prepared as in example 1, and the prepared dodecadibasic acid solution was kept at a constant temperature of 80℃for 1 hour in a crystallizer. Simulating a natural cooling crystallization process, cooling to 81 ℃ at the rate of 3 min/DEG C, cooling to 76 ℃ at the rate of 4 min/DEG C, cooling to 67 ℃ at the rate of 5 min/DEG C, cooling to 63 ℃ at the rate of 6 min/DEG C, cooling to 59 ℃ at the rate of 7 min/DEG C, cooling to 55 ℃ at the rate of 8 min/DEG C, cooling to 53 ℃ at the rate of 9 min/DEG C, cooling to 51 ℃ at the rate of 10 min/DEG C, cooling to 49 ℃ at the rate of 12 min/DEG C, cooling to 46 ℃ at the rate of 13 min/DEG C, cooling to 43 ℃ at the rate of 20 min/DEG C, cooling to 40 ℃ at the rate of 22 min/DEG C, cooling to 34 ℃ at the rate of 22 min/DEG C, and finally filtering, washing with a multiple (relative to the weight of the crude long-chain dibasic acid) of water, and drying at 105 ℃ for 2 hours in a paddle dryer to obtain a dodecadibasic acid product.
The purity of the finished product of the dodecadiacid is 98.02 percent, and compared with the dodecadiacid obtained by the method of the example 1, the purity of the finished product of the dodecadiacid is lower; average particle diameter of 272 μm, D 10 ＝151μm，D 50 ＝245μm，D 90 ＝411μm，D 16 ＝172μm，D 84 The product particles have a large degree of dispersion and are less uniformly distributed, with a coefficient of variation of c.v. = 40.82 =372 μm.
Comparative example 4
The dodecadibasic acid solution was prepared as in example 1, and the prepared dodecadibasic acid solution was kept at a constant temperature of 80℃for 1 hour in a crystallizer. Cooling at constant speed for crystallization, cooling to 35 ℃ at constant speed for 2 min/DEG C, preserving heat for 0.5h at the temperature, finally filtering, washing with one time of water (relative to the weight of the long-chain dicarboxylic acid crude product), and drying at 105 ℃ for 2 hours in a paddle dryer to obtain the dodecadiacid finished product.
The purity of the finished product of the dodecadiacid is 99.52 percent, and is equivalent to that of the dodecadiacid obtained by the method of the example 1; average particle diameter of 377 μm, D 10 ＝206μm，D 50 ＝345μm，D 90 ＝580μm，D 16 ＝234μm，D 84 The product particles have larger dispersion degree and less uniform distribution, and the variation coefficient is 521 mu m and C.V. =41.59%.
Example 2
The twelve-carbon diacid (purity is 99%) and 98wt.% acetic acid are placed in a crystallizer, the mass ratio of the 98wt.% acetic acid converted into 100wt.% acetic acid to the twelve-carbon diacid (purity is 99%) is 2.2:1, and the twelve-carbon diacid is heated to 85 ℃ to obtain the twelve-carbon diacid solution.
In the crystallizer, the dodecadibasic acid solution was kept at a constant temperature of 85℃for 1 hour. Cooling to 60deg.C at the rate of 2 min/deg.C, and separating out the particles in the solution and increasing the particle number. Then heating to 67 ℃ at the rate of 3 min/DEG C, continuously reducing the particle number in the solution, and ending the first temperature cycle; the second temperature cycle, cooling to 52 ℃ at the rate of 2 min/DEG C, and then heating to 59 ℃ at the rate of 3 min/DEG C; the third temperature cycle, cooling to 44 ℃ at the rate of 2 min/DEG C, and then heating to 51 ℃ at the rate of 3 min/DEG C; fourth temperature circulation, cooling to 36 ℃ at the rate of 2 min/DEG C, and heating to 43 ℃ at the rate of 3 min/DEG C; and (3) a fifth temperature cycle, cooling to 28 ℃ at the rate of 2 min/DEG C, heating to 35 ℃ at the rate of 3 min/DEG C, and preserving the temperature for 0.5h. Through five temperature cycles, filtering, washing with water in an amount of one time (relative to the weight of long chain dibasic acid with the purity of 99%), and drying at 105 ℃ for 1 hour in a paddle dryer to obtain the finished product of the dodecadiacid.
The purity of the dodecadiacid finished product is 99.75 percent, and the purity of the product is qualified; the average particle diameter is 328 mu m, D 10 ＝203μm，D 50 ＝320μm，D 90 ＝465μm，D 16 ＝228μm，D 84 427 μm, coefficient of variation c.v. =31.09%, and the product particles have a low degree of dispersion and a uniform distribution.
Comparative example 5
The dodecadibasic acid solution was prepared as in example 2, and the prepared dodecadibasic acid solution was kept at a constant temperature of 85℃for 1 hour in a crystallizer. Cooling to 74 ℃ at the rate of 5 min/DEG C, wherein a small amount of particles are precipitated in the solution and gradually increase, and keeping the temperature for 1h. And (3) starting nonlinear cooling crystallization, wherein the cooling procedure is as follows, cooling to 64 ℃ at the rate of 10 min/DEG C, cooling to 54 ℃ at the rate of 8 min/DEG C, cooling to 44 ℃ at the rate of 6 min/DEG C, cooling to 34 ℃ at the rate of 5 min/DEG C, keeping the temperature for 0.5h at the temperature, filtering, washing with one time of water (relative to the weight of the long-chain dibasic acid with the purity of 99%), and drying at 105 ℃ for 2 hours in a paddle dryer to obtain the finished product of the dodecadiacid.
The purity of the finished product of the dodecadiacid is 99.37 percent, and compared with the dodecadiacid obtained by the method of the example 2, the purity of the finished product of the dodecadiacid is lower; average particle diameter of 302 μm, D 10 ＝135μm，D 50 ＝296μm，
D 90 ＝568μm，D 16 ＝155μm，D 84 The product particles were distributed to a large degree of dispersion and non-uniform with a coefficient of variation c.v. = 57.26 =494 μm.
Comparative example 6
A dodecadibasic acid solution was prepared as in example 2, and the prepared dodecadibasic acid solution was heated to 85 ℃ in a crystallizer and kept at constant temperature for 1 hour. Cooling to 74 ℃ at the rate of 5 min/DEG C, taking the dodecadiacid crystal as a seed crystal, adding 1wt.% of seed crystal (based on the dodecadiacid with the purity of 99 percent), precipitating a large amount of particles in the solution, and keeping the temperature for 1h. Cooling to 64 ℃ at the rate of 10 min/DEG C, cooling to 54 ℃ at the rate of 8 min/DEG C, cooling to 44 ℃ at the rate of 6 min/DEG C, cooling to 34 ℃ at the rate of 5 min/DEG C, keeping the temperature constant for 0.5h at the temperature, finally filtering, washing with one time of water (relative to the weight of the long-chain dibasic acid with the purity of 99%), and drying at 105 ℃ for 2 hours in a paddle dryer to obtain the finished product of the dodecadiacid.
The product has purity of 99.40%, average particle diameter of 263 μm, and D 10 ＝115μm，D 50 ＝236μm，D 90 ＝471μm，D 16 ＝132μm，D 84 The product particles were distributed to a large degree of dispersion and non-uniform in distribution, with a coefficient of variation c.v=416.17=416 μm.
Comparative example 7
A dodecadibasic acid solution was prepared as in example 2, and the prepared dodecadibasic acid solution was heated to 85 ℃ in a crystallizer and kept at constant temperature for 1 hour. Simulating a natural cooling crystallization process, cooling to 81 ℃ at the rate of 3 min/DEG C, cooling to 76 ℃ at the rate of 4 min/DEG C, cooling to 67 ℃ at the rate of 5 min/DEG C, cooling to 63 ℃ at the rate of 6 min/DEG C, cooling to 59 ℃ at the rate of 7 min/DEG C, cooling to 55 ℃ at the rate of 8 min/DEG C, cooling to 53 ℃ at the rate of 9 min/DEG C, cooling to 51 ℃ at the rate of 10 min/DEG C, cooling to 49 ℃ at the rate of 12 min/DEG C, cooling to 46 ℃ at the rate of 13 min/DEG C, cooling to 43 ℃ at the rate of 20 min/DEG C, cooling to 40 ℃ at the rate of 22 min/DEG C, cooling to 34 ℃ at the rate of 22 min/DEG C, and finally filtering, adopting a plurality of water for washing relative to the weight of long-chain diacid with 99% purity, and drying at 105 ℃ for 2 hours to obtain the dodecadiacid product.
The purity of the finished product of the dodecadiacid is 99.15 percent, and compared with the dodecadiacid obtained by the method of the example 2, the purity of the finished product of the dodecadiacid is lower; average particle diameter of 286 μm, D 10 ＝161μm，D 50 ＝255μm，D 90 ＝431μm，D 16 ＝182μm，D 84 The product particles have larger discrete degree and less uniform distribution, and the variation coefficient is equal to or smaller than 392 mu m and C.V. = 41.17%.
Comparative example 8
A dodecadibasic acid solution was prepared as in example 2, and the prepared dodecadibasic acid solution was heated to 85 ℃ in a crystallizer and kept at constant temperature for 1 hour. Cooling at constant speed for crystallization, cooling to 35 ℃ at constant speed for 2 min/DEG C, preserving heat for 0.5h at the temperature, finally filtering, washing with one time of water (relative to the weight of the long-chain dibasic acid with the purity of 99%), and drying for 2 h at 105 ℃ in a paddle dryer to obtain the finished product of the dodecadiacid.
The purity of the finished product of the dodecadiacid is 99.28 percent, and is equivalent to that of the dodecadiacid obtained by the method of the example 2; average particle diameter of 387 μm, D 10 ＝226μm，D 50 ＝345μm，D 90 ＝590μm，D 16 ＝254μm，D 84 561 μm, coefficient of variation c.v. = 44.49%, the product particles have a large degree of dispersion and are less uniformly distributed.
Example 3
The undecanedioic acid (purity is 99.1%) and acetic acid with a content of 95wt.% are placed in a crystallizer, the mass ratio of the acetic acid with 95wt.% to the undecanedioic acid with a purity of 99.1% is 2.8:1 after the acetic acid with 95wt.% is converted into the acetic acid with a content of 100wt.%, and the undecanedioic acid is heated to 80 ℃ to obtain an undecanedioic acid solution, and the undecanedioic acid solution is kept at a constant temperature of 80 ℃ for 1h. Cooling to 55deg.C at a rate of 3 min/deg.C, maintaining at this temperature for 10min, and precipitating particles in the solution and increasing the number of particles. Heating to 60 ℃ at the rate of 5 min/DEG C, preserving heat for 10min at the temperature, continuously reducing the particle number in the solution, and ending the first temperature cycle; the second temperature cycle, cooling to 50 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature, heating to 55 ℃ at the rate of 5 min/DEG C, preserving heat for 10min at the temperature; third temperature circulation, cooling to 45 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature, heating to 50 ℃ at the rate of 5 min/DEG C, and preserving heat for 10min at the temperature; fourth temperature circulation, cooling to 40 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature, heating to 45 ℃ at the rate of 5 min/DEG C, and preserving heat for 10min at the temperature; the fifth temperature cycle is carried out, the temperature is reduced to 35 ℃ at the rate of 3 min/DEG C, the temperature is kept for 10min, the temperature is increased to 40 ℃ at the rate of 5 min/DEG C, the temperature is kept for 10min at the temperature, the sixth temperature cycle is carried out, the temperature is reduced to 30 ℃ at the rate of 3 min/DEG C, the temperature is kept for 10min, the temperature is increased to 35 ℃ at the rate of 5 min/DEG C, and the temperature is kept for 0.5h. After six temperature cycles, filtering, washing with water in an amount of one time (relative to the weight of the long-chain dibasic acid with the purity of 99.1 percent), and drying at 105 ℃ for 1.5 hours in a paddle dryer to obtain the undecanedioic acid finished product.
The purity of the undecanedioic acid finished product is 99.61 percent, and the purity of the product is qualified; average particle diameter of 421 μm, D 10 ＝226μm，D 50 ＝432μm，D 90 ＝586μm，D 16 ＝273μm，D 84 The product has low dispersion degree of particles and uniform distribution, and the variation coefficient is 549 mu m and C.V. = 31.94%.
Example 4
A final product of dodecanedioic acid was obtained under the same conditions as in example 2, except that the mass ratio of the 98wt.% acetic acid to the 99% pure dodecanedioic acid was 5:1, converted to acetic acid having a content of 100 wt.%.
The purity of the dodecadiacid finished product is 99.65 percent, and the purity of the product is qualified; average particle diameter of 251 μm, D 10 ＝136μm，D 50 ＝272μm，D 90 ＝380μm，D 16 ＝160μm，D 84 The product particles have low dispersion degree and uniform distribution, and the variation coefficient is 347 mu m and C.V. = 34.38%.
Example 5
The twelve-carbon diacid (purity is 99%) and 98wt.% acetic acid are placed in a crystallizer, the mass ratio of the 98wt.% acetic acid converted into 100wt.% acetic acid to the 99.2% twelve-carbon diacid is 2.2:1, the twelve-carbon diacid is heated to 85 ℃ to obtain the twelve-carbon diacid solution, and the twelve-carbon diacid solution is kept at the constant temperature of 85 ℃ for 1h. Cooling to 65deg.C at a rate of 2 min/deg.C, maintaining at this temperature for 10min, and precipitating particles in the solution and increasing the number of particles. Heating to 67 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature, continuously reducing the particle number in the solution, and ending the first temperature cycle; the second temperature cycle, cooling to 62 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 65 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; the third temperature cycle, cooling to 60 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 63 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; fourth temperature circulation, cooling to 58 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 61 ℃ at the rate of 3 min/DEG C, and preserving heat for 10min at the temperature; a fifth temperature cycle, cooling to 56 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 59 ℃ at the rate of 3 min/DEG C, and preserving heat for 10min at the temperature; a sixth temperature cycle of cooling to 54 ℃ at a rate of 2 min/DEG C, maintaining the temperature at the temperature for 10min, and raising the temperature to 57 ℃ at a rate of 3 min/DEG C, and maintaining the temperature at the temperature for 10min; a seventh temperature cycle, cooling to 52 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 55 ℃ at the rate of 3 min/DEG C, and preserving heat for 10min at the temperature; eighth temperature cycle, cooling to 50 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 53 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; a ninth temperature cycle, cooling to 48 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 51 ℃ at the rate of 3 min/DEG C, and preserving heat for 10min at the temperature; a tenth temperature cycle, cooling to 46 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 49 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; an eleventh temperature cycle, cooling to 44 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 47 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; a twelfth temperature cycle, cooling to 42 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 45 ℃ at the rate of 3 min/DEG C, and preserving heat for 10min at the temperature; a thirteenth temperature cycle, cooling to 40 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 43 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; a fourteenth temperature cycle, cooling to 38 ℃ at a rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 41 ℃ at a rate of 3 min/DEG C, preserving heat for 10min at the temperature; a fifteenth temperature cycle, cooling to 36 ℃ at a rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 39 ℃ at a rate of 3 min/DEG C, preserving heat for 10min at the temperature; a sixteenth temperature cycle, cooling to 34 ℃ at a rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 37 ℃ at a rate of 3 min/DEG C, and preserving heat for 10min at the temperature; seventeenth temperature cycle, cooling to 32 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 35 ℃ at the rate of 3 min/DEG C, and preserving heat for 0.5h at the temperature. After seventeen temperature cycles, filtering, adopting one time of water (relative to the weight of the long-chain dibasic acid with the purity of 99.2 percent) to wash, and drying for 1.5 hours at 105 ℃ in a paddle dryer to obtain the finished product of the dodecandioic acid.
The purity of the dodecadiacid finished product is 99.72 percent, and the purity of the product is qualified; average particle diameter of 332 μm, D 10 ＝193μm，D 50 ＝315μm，D 90 ＝459μm，D 16 ＝221μm，D 84 The product particles have a low degree of dispersion and a uniform distribution, and the variation coefficient c.v. =31.90% =422 μm.
Example 6
Twelve-carbon diacid (purity is 99%) and 98wt.% acetic acid are placed in a crystallizer, the mass ratio of the 98wt.% acetic acid converted into 100wt.% acetic acid to the 99% twelve-carbon diacid is 2.2:1, the twelve-carbon diacid is heated to 80 ℃ to obtain a twelve-carbon diacid solution, and the twelve-carbon diacid solution is kept at the constant temperature of 80 ℃ for 1h. Cooling to 60deg.C at the rate of 2 min/deg.C, maintaining at this temperature for 10min, and separating out the particles in the solution and increasing the number of particles. Heating to 67 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature, continuously reducing the particle number in the solution, and ending the first temperature cycle; the second temperature cycle, cooling to 52 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 59 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; the third temperature cycle, cooling to 44 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 51 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; fourth temperature cycle, cooling to 36 ℃ at the rate of 2 min/DEG C, preserving heat for 10min at the temperature, heating to 43 ℃ at the rate of 3 min/DEG C, preserving heat for 10min at the temperature; and (3) a fifth temperature cycle, cooling to 30 ℃ at a rate of 3 min/DEG C, preserving heat for 30min at the temperature, filtering, washing with one time of water (relative to the weight of the long-chain dibasic acid with the purity of 99%), and drying at 105 ℃ for 1.5 hours in a paddle dryer to obtain the finished product of the dodecadiacid.
The purity of the dodecadiacid finished product is 99.63 percent, and the purity of the product is qualified; the average particle diameter is 308 mu m, D 10 ＝198μm，D 50 ＝316μm，D 90 ＝455μm，D 16 ＝213μm，D 84 The product particles have a low degree of dispersion and a uniform distribution, with a coefficient of variation c.v. =31.80%, and 414 μm.
Example 7
Twelve carbon diacid (purity is 99%) and 98wt.% acetic acid are placed in a crystallizer, the mass ratio of the 98wt.% acetic acid converted into 100wt.% acetic acid to 99% twelve carbon diacid is 3.0:1, and the twelve carbon diacid is heated to 85 ℃ to obtain clear twelve carbon diacid solution. Cooling to 60deg.C at a rate of 3 min/deg.C, and precipitating and increasing the number of particles in the solution. Then heating to 67 ℃ at the rate of 2 min/DEG C, continuously reducing the particle number in the solution, and ending the first temperature cycle; the second temperature cycle, cooling to 52 ℃ at the rate of 3 min/DEG C, and then heating to 59 ℃ at the rate of 2 min/DEG C; the third temperature cycle, cooling to 44 ℃ at the rate of 3 min/DEG C, and then heating to 51 ℃ at the rate of 2 min/DEG C; fourth temperature circulation, cooling to 36 ℃ at the rate of 3 min/DEG C, and heating to 43 ℃ at the rate of 2 min/DEG C; and (3) cooling to 28 ℃ at the rate of 3 min/DEG C for a fifth temperature cycle, heating to 35 ℃ at the rate of 2 min/DEG C, and preserving the temperature for 0.5h. After five temperature cycles, filtering, washing with water in an amount of one time (relative to the weight of the long-chain dibasic acid with the purity of 99%), and drying at 105 ℃ for 1 hour in a paddle dryer to obtain the finished product of the dodecadiacid.
The purity of the dodecadiacid finished product is 99.84 percent, and the purity of the product is qualified; average particle diameter of 336 μm, D 10 ＝208μm，D 50 ＝336μm，D 90 ＝479μm，D 16 ＝235μm，D 84 443 μm, coefficient of variation c.v. =30.95%, and the product particles have a lower degree of dispersion and a more uniform distribution.
Test case
The samples obtained in examples 1 to 7 and comparative examples 1 to 8 were taken and tested for particle size, light transmittance and moisture, and the results are shown in tables 1 to 3 below. The result shows that the long-chain binary acid product obtained by the process has good granularity and fluidity.
TABLE 1
The results of the particle size analyses of the products of examples 1 and 2 and comparative examples 1 to 8 are shown in tables 2 and 3 below, and the method of temperature cycle control is adopted to effectively control the purity, average particle size and variation coefficient c.v. of the diacid product, and the product prepared by the method has the advantages of qualified purity, uniform particle distribution, few fine particles, improved subsequent process performance such as very good filtration performance, improved production efficiency, and greatly reduced production cost. The comparative example 1 adopts nonlinear cooling control to obtain a product with uneven particle size distribution and lower purity, the comparative example 2 introduces seed crystals on the basis of the comparative example 1, the purity is qualified, but the product has uneven particle size distribution, the comparative example 3 simulates natural cooling trend, and the purity of the obtained product is also unqualified. Comparative example 4 uses the same cooling rate as the example to cool, but the product particles are not uniformly distributed although the purity is acceptable.
Table 2 comparison of results of particle size tests
| Particle size distribution | Example 1 | Comparative example 1 | Comparative example 2 | Comparative example 3 | Comparative example 4 |
| Average value/. Mu.m | 319 | 319 | 273 | 272 | 377 |
| D 10 /μm | 195 | 139 | 120 | 151 | 206 |
| D 50 /μm | 311 | 286 | 246 | 245 | 345 |
| D 90 /μm | 452 | 548 | 461 | 411 | 580 |
| C.V./％ | 31.99 | 54.02 | 53.66 | 40.82 | 41.59 |
| Purity/% | 99.73 | 98.36 | 99.45 | 98.02 | 99.52 |
| Total nitrogen content/ppm | 21 | 28 | 33 | 39 | 34 |
| Transmittance/% | 99.4 | 98.7 | 98.9 | 98.2 | 99.2 |
| Moisture/% | 0.15 | 0.79 | 0.48 | 0.66 | 0.37 |
Table 3 comparison of results of particle size tests
| Particle size distribution | Example 2 | Comparative example 5 | Comparative example 6 | Comparative example 7 | Comparative example 8 |
| Average value/. Mu.m | 328 | 302 | 263 | 286 | 387 |
| D 10 /μm | 203 | 135 | 115 | 161 | 226 |
| D 50 /μm | 320 | 296 | 236 | 255 | 345 |
| D 90 /μm | 465 | 568 | 471 | 431 | 590 |
| C.V./％ | 31.09 | 57.26 | 60.17 | 41.17 | 44.49 |
| Purity/% | 99.75 | 99.37 | 99.40 | 99.15 | 99.28 |
| Total nitrogen content/ppm | 18 | 31 | 37 | 35 | 30 |
| Transmittance/% | 99.3 | 99.0 | 99.1 | 98.7 | 98.9 |
| Moisture/% | 0.11 | 0.45 | 0.32 | 0.52 | 0.38 |
Comparing the data in tables 2 and 3, it can be seen that long chain dibasic acids with concentrated particle size can also be prepared using crude long chain dibasic acids.
After the experiments of the inventor, the average particle diameter of the long-chain dibasic acid is 250-450 mu m, D 10 100-250 mu m, D 50 250-450 mu m, D 90 When the variation coefficient C.V. is 30-40%, the particle size of the particles is favorable for improving the purity of the long-chain dibasic acid, and the mother solution content adhered to the surfaces of the particles is reduced because the particle size is large and the specific surface is smaller, the residual rate of the mother solution on the surfaces of the particles in the washing process is lower, and accordingly, the probability of residual impurities dissolved in the mother solution on the surfaces of the particles is reduced, so that the purity of the product is improved. In addition, the particle size of the long-chain dicarboxylic acid product is larger, the long-chain dicarboxylic acid product is easy to filter, the filtering time is shorter, the appearance color of the obtained long-chain dicarboxylic acid product is light, the total nitrogen content is low, the light transmittance is high, and the water content of the product is lower.
In comprehensive consideration, the method can effectively control the granularity of the product, thereby being beneficial to the improvement of the efficiency of the subsequent process and obtaining the qualified product.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (22)
1. A long-chain dicarboxylic acid product with concentrated particle size distribution is characterized in that the average particle size of the long-chain dicarboxylic acid product is 250-450 mu m,
10% cumulative volume particle size D 10 Is in the range of 100 to 250 mu m,
50% cumulative volume particle size D 50 Is in the range of 250 to 450 mu m,
90% cumulative volume particle size D 90 Is in the range of 350 to 600 mu m,
the variation coefficient C.V. is 30-40%, and the purity is over 99.6%;
the preparation method of the long-chain dibasic acid product with concentrated particle size distribution comprises the following steps:
A. Dissolving a long-chain dibasic acid and/or a mixture comprising a long-chain dibasic acid in an organic solvent;
the organic solvent is selected from the group consisting of alcohols, monoacids and mixtures of two or more thereof;
B. the following steps are repeated in a cyclic manner:
b-1: cooling to a temperature T 2M When particles are separated out from the solution, the solution is kept at the temperature for a period of time U 2M Or directly carrying out the next step;
and, a step of, in the first embodiment,
b-2: heating to a temperature T 3M The number of particles in the solution is reduced, and the solution is kept at the temperature for a period of time U 3M Or directly carrying out the next step;
c: after repeating the N-th cycle of the cycle step B, the temperature T is adjusted 4 Holding time U at this temperature 4 Or directly carrying out the next step;
d: separating, washing and drying to obtain a long-chain dibasic acid finished product with concentrated particle size distribution;
m represents the Mth cycle, M is an integer greater than or equal to 1;
and the temperature T of the Mth cycle 2M Temperature T of M+1st cycle 2(M+1) ；
The temperature of the Mth cycleDegree T 3M Temperature T of M+1st cycle 3(M+1) ；
Temperature T of the Mth cycle 2M And temperature T of the M+1st cycle 2(M+1) The difference between the temperature and the temperature of the M th cycle is 0-15 ℃, the temperature of the M th cycle is T 3M And temperature T of the M+1st cycle 3(M+1) The difference value is 0-15 ℃;
Said temperature T 4 15-35 ℃;
and (C) repeating the step B for 1-20 times.
2. The long-chain dibasic acid product having concentrated particle size distribution according to claim 1, wherein the long-chain dibasic acid product has an average particle diameter of 250 to 430 μm,
10% cumulative volume particle size D 10 Is in the range of 100 to 230 mu m,
50% cumulative volume particle size D 50 In the range of 250 to 440 mu m,
90% cumulative volume particle size D 90 Is in the range of 370 to 590 mu m,
the coefficient of variation C.V. is 30-36%.
3. A method for preparing a long chain dibasic acid having a concentrated particle size distribution, the method comprising the steps of:
A. dissolving a long-chain dibasic acid and/or a mixture comprising a long-chain dibasic acid in an organic solvent;
the organic solvent is selected from the group consisting of alcohols, monoacids and mixtures of two or more thereof;
B. the following steps are repeated in a cyclic manner:
b-1: cooling to a temperature T 2M When particles are separated out from the solution, the solution is kept at the temperature for a period of time U 2M Or directly carrying out the next step;
and, a step of, in the first embodiment,
b-2: heating to a temperature T 3M The number of particles in the solution is reduced, and the solution is kept at the temperature for a period of time U 3M Or directly carrying out the next step;
c: after repeating the step B and the Nth cycle, adjustingTo a temperature T 4 Holding time U at this temperature 4 Or directly carrying out the next step;
d: separating, washing and drying to obtain a long-chain dibasic acid finished product with concentrated particle size distribution;
m represents the Mth cycle, M is an integer greater than or equal to 1;
and the temperature T of the Mth cycle 2M Temperature T of M+1st cycle 2(M+1) ；
Temperature T of the Mth cycle 3M Temperature T of M+1st cycle 3(M+1)
Temperature T of the Mth cycle 2M And temperature T of the M+1st cycle 2(M+1) The difference between the temperature and the temperature of the M th cycle is 0-15 ℃, the temperature of the M th cycle is T 3M And temperature T of the M+1st cycle 3(M+1) The difference value is 0-15 ℃;
said temperature T 4 15-35 ℃;
and (C) repeating the step B for 1-20 times.
4. A method according to claim 3, wherein the long chain diacid is a saturated or unsaturated linear diacid having 10 to 18 carbon atoms with carboxyl groups at both ends of the carbon chain, or a mixture of any two or more of the foregoing.
5. The method of claim 4, wherein the long chain diacid is selected from the group consisting of sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanoic acid, hexadecanedioic acid, heptadecanoic acid, octadecanedioic acid, and 9-ene-octadecanedioic acid.
6. A process according to claim 3, wherein the organic solvent is selected from acetic acid, acetic acid C 1 -C 6 Alcohol esters, C 1 -C 6 And mixtures of two or more thereof.
7. The method of claim 3, wherein,
the number of times N of the repeated circulation step B is 2-20 times;
and M is an integer of 1 or more and (N-1) or less.
8. The method of claim 7, wherein,
the number of times N of the repeated circulation step B is 2-15 times;
m is 1-19.
9. The method of claim 8, wherein M is 1 to 14.
10. A method according to claim 3, wherein in step a, the dissolving comprises the steps of: mixing the long-chain dibasic acid and/or the mixture comprising the long-chain dibasic acid with an organic solvent, and regulating the temperature of the system to T 1 Dissolving.
11. The method of claim 10, wherein when said mixture comprising long chain dibasic acid is crude long chain dibasic acid, further comprising the steps of post-dissolving, decolorizing, filtering, and proceeding.
12. The method of claim 10, wherein,
the temperature of the system is regulated to T 1 Hold time U 1 Dissolving.
13. The method of claim 12, wherein said time U 1 For 0.5 to 2 hours; and/or the number of the groups of groups,
said time U 2M For 0 to 2 hours; and/or the number of the groups of groups,
said time U 3M For 0 to 2 hours; and/or the number of the groups of groups,
said temperature T 1 Precipitation of longer-chain dibasic acids in the solutionThe temperature is 1-40 ℃.
14. The method of claim 13, wherein said time U 1 For 0.5 to 1 hour; and/or the number of the groups of groups,
said time U 2M For 0 to 1 hour; and/or the number of the groups of groups,
said time U 3M For 0 to 1 hour;
said temperature T 1 The precipitation temperature of the long-chain dibasic acid in the solution is 10-20 ℃ higher than that of the long-chain dibasic acid.
15. The method of claim 14, wherein the temperature T 1 The precipitation temperature of the long-chain dibasic acid in the solution is 5 ℃, 8 ℃, 13 ℃, 17 ℃, 23 ℃, 28 ℃, 32 ℃ or 37 ℃ higher than that of the long-chain dibasic acid.
16. The method of claim 10, wherein,
the cooling speed in the Mth cycle is the same as the cooling speed of the M+1th cycle; and/or the number of the groups of groups,
time U in the Mth cycle 2M Time U as in the M+1th cycle 2(M+1) In accordance with the method, the device and the system,
time U in the Mth cycle 3M Time U as in the M+1th cycle 3(M+1) And consistent.
17. The method of claim 3, wherein,
temperature T of the Mth cycle 2M And temperature T of the M+1st cycle 2(M+1) The difference value is 0-10 ℃; and/or the number of the groups of groups,
temperature of the Mth cycle T 3M And temperature T of the M+1st cycle 3(M+1) The difference between them is 0-10 deg.C.
18. The method of claim 10, wherein the temperature rise rate in the mth cycle is 1-5 min/°c faster than the temperature rise rate in the m+1th cycle or the temperature rise rate in the mth cycle is 1-5 min/°c slower than the temperature rise rate in the m+1th cycle.
19. The method of claim 3, wherein,
said time U 4 For 0 to 2 hours; and/or the number of the groups of groups,
in the step C, the temperature is reduced or increased, the temperature reduction speed is 0.5-10 min/DEG C, and the temperature increase speed is 0.5-10 min/DEG C.
20. The method of claim 19, wherein the temperature T 4 20-35 ℃; and/or the number of the groups of groups,
said time U 4 For 0 to 1 hour; and/or the number of the groups of groups,
in the step C, the cooling speed is 1-5 min/DEG C, and the heating speed is 1-5 min/DEG C.
21. The method of claim 20, wherein the temperature T 4 25-35 ℃; and/or the number of the groups of groups,
in the step C, the cooling speed is 2-4 min/DEG C, and the heating speed is 2-4 min/DEG C.
22. The method of claim 21, wherein the temperature T 4 Is 30-35 ℃.
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