CN109265355B

CN109265355B - Pentanediamine suberate salt and crystal thereof

Info

Publication number: CN109265355B
Application number: CN201811201325.0A
Authority: CN
Inventors: 杨朋朋; 应汉杰; 李子涵; 王森; 黎青青; 李晓洁; 庄伟�; 吴菁岚; 欧阳平凯
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2018-10-16
Filing date: 2018-10-16
Publication date: 2021-06-25
Anticipated expiration: 2038-10-16
Also published as: CN109265355A

Abstract

The invention discloses pentanediamine suberate and a crystal structure thereof, and a preparation method thereof. The pentanediamine suberate salt is a salt which is formed by combining pentanediamine divalent cations and suberic acid divalent anions in a molar ratio of 1:1 and is in a solid state at normal temperature. The crystal structure is C₁₃H₂₈N₂O₄Monoclinic system, C2/C space group,

α is 90.00 °, β is 117.673(4 °), γ is 90.00 °, unit cell volume

Description

Pentanediamine suberate salt and crystal thereof

Technical Field

The invention belongs to the technical field of monomer crystallization of bio-based materials, and particularly relates to monomer pentanediamine suberate of bio-based nylon 58, a crystal structure thereof, crystal powder thereof and a preparation method thereof.

Background

The nylon 58 is a synthetic material polymerized by bio-based pentanediamine (1-5-Diaminopentane, also known as Cadaverine (cadeverine) and petroleum-based suberic acid), has good mechanical properties, is still in a laboratory stage in the academic community of application research, and is expected to become a new polyamide material which is promoted to the market.

Disclosure of Invention

The invention aims to solve the technical problem of providing a high-purity pentanediamine suberate salt with the mole ratio of pentanediamine to suberic acid and a crystal thereof, and providing a preparation process of the pentanediamine suberate crystal salt. The pentanediamine suberic acid crystalline salt prepared by the invention can be directly used as a monomer for polymerizing nylon 58. The polymerization reaction scheme is shown as formula III:

the invention aims to provide a monomer of a bio-based nylon 58 material, pentanediamine suberate, a crystal structure thereof, a crystal powder thereof and a preparation method thereof. Compared with the traditional nylon 58 polymerization process which can be carried out by two components of the pentanediamine and the suberic acid, the pentanediamine suberate product provided by the invention is obtained by a crystallization mode, is presented in a mode of crystals with equal molar ratio of the pentanediamine to the suberic acid, can be directly used for polymerization, has the advantages of structural stability, high chemical purity, good granularity and good transportation, use, storage and quality.

The technical scheme adopted by the invention is as follows:

the invention discloses a solid pentanediamine suberate, also called cadaverine suberate, which is a salt in a solid state at normal temperature and formed by combining pentanediamine divalent cations and suberic acid divalent anions in a molar ratio of 1:1, and the molecular structure of the salt is shown as a formula I:

the invention also discloses a crystal of the pentanediamine suberate, and the molecular formula of the pentanediamine suberate is C₁₃H₂₈N₂O₄And crystal water is not contained, and the molecular structural formula is shown as formula II:

the crystal structure of the pentanediamine suberate salt of the invention belongs to a monoclinic system, C2/C space group,

alpha 90.00 deg., beta 117.673(4 deg.), gamma 90.00 deg., unit cell volume

The minimum number of asymmetric units in the unit cell, Z, is 4. In its smallest asymmetric unit, it contains 1 pentanediamine cation and 1 suberic acid anion. The minimum asymmetric unit diagram of the unit cell is basically shown in figure 1, the structure diagram of the unit cell is basically shown in figure 2, the stacking diagram of the unit cell is basically shown in figure 3, the detailed data of the crystal structure, namely bond length information, is basically shown in figure 9, the bond angle information is basically shown in figure 10, and the dihedral angle information is basically shown in figure 11As shown, the hydrogen bonding information is substantially as shown in fig. 12. During the determination of the crystal structure, diffraction data are collected at 298(2) K.

The crystal of pentanediamine suberate of the present invention has a diffraction pattern obtained by diffraction analysis using CuK α rays as characteristic X-rays, substantially as shown in fig. 4, and its X-ray powder diffraction reflection angle 2 θ ± 0.1, corresponding d-value and relative peak intensity are shown in fig. 7.

The detection method and the detection instrument of the crystal structure of the pentanediamine suberate obtained by the invention are as follows:

the single crystal X-ray diffraction measurement crystal structure and the analysis method are as follows: collecting the cultured single crystal of pentanediamine suberate with good quality, and cutting into about 0.12 × 0.21 × 0.45mm³The block with the size is obtained by a Bruk APEX-II CCD diffractometer Mo Kalpha radioactive source (a graphite monochromator,

) Irradiating the sample, collecting diffraction data, reducing the diffraction data by SAINT, performing structural analysis by SHELXL-97 software direct method, and analyzing the structure based on F²The full matrix least squares refinement of (a), all non-hydrogen atoms are refined by anisotropy. The final data are plotted by Mercury 3.3 or Materials Studio 7.0 software.

Powder X-ray diffraction: about 0.1g of the ground sample was used for collection of diffraction data at room temperature by a powder X-ray diffractometer (Smartlab, Japan, or Bruker D8 Advance) using CuK alpha rays

The scanning step is 0.02 degrees, the scanning voltage is set to be 40kV, the current is set to be 40mA, the scanning speed is 0.2s/0.02 degrees, the scanning range 2 theta is 5-50 degrees, and the data are processed and plotted by JADE 6.5 software.

Thermogravimetric Analysis (TG or TGA): about 5mg of the sample was placed in an aluminum crucible of a thermogravimetric analyzer (TGA Q500V 20.13 Build 39)Heating at room temperature-350 deg.C at a heating rate of 10k/min, and purging carrier gas N₂And air, the balance carrier gas is nitrogen, and the purging speed is 40 ml/min; the sample carrier gas was nitrogen and the purge rate was 60 ml/min.

Differential Scanning calorimetry (Differential Scanning calorimeter, DSC): about 5mg of the sample was placed in an aluminum crucible of a DSC analyzer (DSC Q2000V 24.11 built 124) for heating analysis, the heating temperature was set from room temperature to 350 ℃, the heating rate was 10k/min, and both

purge carrier gases

1 and 2 were N₂The purge rate was 50 ml/min.

The crystalline powder of pentamethylenediamine suberate was white.

The crystals form a crystalline powder having a bulk density greater than 0.22g/mL, preferably greater than 0.30g/mL, more preferably greater than 0.36 g/mL.

The crystals form a crystalline powder having a tap density greater than 0.25g/mL, preferably greater than 0.33g/mL, more preferably greater than 0.40 g/mL.

A crystalline powder formed of the above crystals having a d of more than 30 μm₅₀Preferably more than 40 μm, more preferably more than 45 μm.

A crystalline powder formed of the above crystals having a d of more than 11 μm₁₀Preferably more than 15 μm, more preferably more than 18 μm.

D in the invention₅₀And d₁₀Are typical amounts used to indicate particle size distribution. D is₅₀Is a value for particle size such that 50 vol.% of the crystals have a size less than this value. D is₁₀Is a value for the particle size such that 10 vol.% of the crystals have a size below this value.

The bulk and tap densities are quantities related to the flow characteristics of the powder. In general, high bulk and tap density values are desired. Bulk density refers to the weight per volume unit of powder under predetermined conditions, expressed as weight per volume unit, typically in g/mL. Tap density also indicates the weight per volume unit of powder in which holder the powder is subjected to tapping or vibration under predetermined conditions. Tap density is expressed as weight per volume unit, usually in g/mL. More powder can be fed into the holder by beating or vibrating. Thus, for the same powder, the tap density is higher than the bulk density.

The powder with large bulk density and tap density has large specific gravity, can reflect that the crystal product is thick and solid and has texture, and has relatively good stability; in another aspect, the flowability of the granules is generally better for products with high bulk density, and the granules are also convenient for storage and transportation.

Then, specifically, the measurement methods of the crystal powder particle size distribution, the bulk density, and the tap density are as follows:

particle size distribution (including d) of samples from the mixer was determined using a Microtrac S3500 particle size Analyzer₁₀And d₅₀) Wet determination;

bulk density of the granules was determined according to USP method II (page 1914);

the tap density of the particles was determined by means of an economical tap density determinator of FZS4-4 in accordance with GB/T5162-2006. Specifically, the measurement conditions were: the vibration stroke of the compaction device is 3 +/-0.1 MM, and the vibration frequency is 250 +/-15 times per minute.

When the crystal is prepared into an aqueous solution with the mass fraction of 5%, the pH value of the system is between 4.1 and 10.0, preferably between 5.5 and 9.0, and more preferably between 6.0 and 8.0.

The solid or solid powder of the present invention is an aggregated state of matter, including amorphous and crystalline.

The crystalline powder of the present invention refers to a powder having a certain degree of crystallinity, as opposed to being amorphous.

The crystal is a solid with definite diffraction pattern for X-ray, and its atoms or molecules are arranged in space according to a certain regular period.

The invention also discloses a composition comprising

(i) The crystals of pentanediamine suberate salt of the present invention and

(ii) (a) suberic acid; or

(b) Pentanediamine.

The composition is such that the ratio of moles of pentanediamine to moles of suberic acid in the mixture is not equal to 1: 1.

The invention finally discloses a process for the preparation of the above mentioned crystals of pentanediamine suberate salt, comprising crystallizing pentanediamine suberate salt from a solution containing dissolved pentanediamine and suberic acid; separating the crystals from the solution; the separated crystals were dried.

Wherein the mechanical pressing is carried out on the crystal during or after the drying process.

Wherein the solution containing the dissolved pentanediamine and the suberic acid is prepared by any one of the following modes:

(i) adding suberic acid and pentanediamine into a solvent simultaneously;

(ii) adding suberic acid and pentanediamine into a solvent in sequence;

(iii) adding pentamethylene diamine into a solvent to form pentamethylene diamine solution; adding suberic acid to a solvent to form an suberic acid solution or an suberic acid solution containing a portion of undissolved suberic acid solids, and then mixing the two; the solvent for dissolving the pentamethylene diamine and the solvent for dissolving the suberic acid may be the same or different.

Wherein, the solvent comprises one or more of methanol, ethanol, water, n-propanol, ethyl acetate, ethyl formate, methyl acetate, isopropanol, acetone, butanone, petroleum ether, tetrahydrofuran and DMSO.

The addition of the suberic acid can be varied, for example, by adding the suberic acid directly to the solvent in solid form at one time, or slowly adding the suberic acid to the solvent in solid form several times, or by dissolving the suberic acid in the solvent and then adding the suberic acid to the cadaverine solution at one time or several times. Preferably, the suberic acid is dissolved in the solvent and then added to the cadaverine solution.

The preparation method of the pentanediamine suberate salt crystal comprises the following steps of adding pentanediamine into an organic solvent, or into a binary solvent of water and the organic solvent, or into a mixed solvent of water and various organic solvents, or into a water phase, fully and uniformly mixing, adding suberic acid, slowly crystallizing at the temperature of 10-60 ℃ under a stirring state, precipitating white crystals after 1-72 hours, carrying out solid-liquid separation on crystal slurry through suction filtration or centrifugation, and drying the obtained solid at the temperature of 35-80 ℃ in vacuum to obtain pentanediamine suberate salt crystal powder or the composition.

Wherein the ratio of the weight g of the pentamethylene diamine to the volume mL of the solvent in the crystal preparation process can be 1: 0.5-20; the molar ratio of the suberic acid to the pentanediamine may be 0.4 to 2.0, and an equimolar ratio is preferred.

It should be noted that when pentanediamine and suberic acid are crystallized by reaction in an equimolar ratio, the solid product obtained is more likely to form pentanediamine suberate crystals in an equimolar ratio of pentanediamine cation to suberic acid anion, and the pH of the 5 wt% aqueous solution is 6.0 to 8.0, preferably 6.5 to 7.5. If the total moles of suberic acid added during the crystal preparation are greater than or less than the moles of pentanediamine initially added, the resulting solid product will more readily form the composition of the present invention, and the pH of a 5 wt% aqueous solution of the product will exhibit non-neutrality.

Specifically, when the number of moles of suberic acid added is greater than the number of moles of the initial pentamethylenediamine, the resulting powder will exhibit weak acidity or acidity; when the number of moles of suberic acid added is less than the number of moles of the initial pentanediamine, the resulting powder will exhibit weak basicity or basicity.

It should be noted that, in the preparation method of the present invention, after the solid-liquid separation, a detergent is needed to wash the solid to remove impurities in the crystallization mother liquor carried on the surface of the solid, and the detergent may be the solvent used in the crystallization preparation process.

It should be noted that in the preparation method of the invention, the drying process has certain influence on the quality of the pentanediamine suberate powder, and the lower drying temperature may cause the phenomenon of overproof solvent residue or agglomeration caused by insufficient drying; too high a drying temperature tends to yellow the product. According to the preparation method, the drying mode is preferably vacuum drying and blast drying, the drying temperature can be 35-80 ℃, preferably 40-70 ℃, and the vacuum degree is lower than 300mbar, preferably lower than 100mbar, and more preferably lower than 50 mbar.

It should be noted that in the preparation method of the present invention, the source of the pentanediamine in the process may be a single component of the pentanediamine, or a solution containing the pentanediamine at the later stage of separation in the preparation process of the pentanediamine by a biological method.

It is noted that the crystallization process may be carried out batchwise or continuously. When the process is carried out batchwise, it is preferred to add seed crystals to the crystallization system. Preferably, the crystallization is carried out continuously.

Further, more detailed information on the crystal structure of pentanediaminoctanedioate according to the present invention is given in the drawings of the specification.

Has the advantages that: compared with the prior art, the invention has the following advantages:

(1) the invention leads the pentanediamine and the suberic acid to be directly combined to form solid salt, thereby not only changing the existing form of the pentanediamine and improving the stability of the product, but also greatly reducing the original odor and being beneficial to improving the working environment of workers in the polymerization section; (2) the nylon 58 crystal salt provided by the invention is convenient to store and transport, and the operability of a subsequent polymerization process is improved; (3) the nylon 58 monomer salt provided by the invention exists in a highly crystallized state, has high purity, and can be directly used for polymerization of nylon 58.

Drawings

FIG. 1 is a molecular ellipsoid plot of the smallest asymmetric unit of pentanediamine suberate;

FIG. 2 is a schematic diagram of a unit cell of pentanediamine suberate along the b-axis;

FIG. 3 is a diagram of the unit cell stacking along the b-axis of pentanediamine suberate;

FIG. 4X-ray powder diffraction pattern of pentanediamine suberate;

FIG. 5 TG analysis of pentanediamine suberate;

FIG. 6 DSC profile of pentanediamine suberate;

FIG. 7 characteristic lines of X-ray powder diffraction of pentanediamine suberate;

FIG. 8 pentanediamine suberate crystal and information related to its structure;

FIG. 9 bond length information in pentanediamine suberate structure (Angstrom);

FIG. 10 bond angle information in pentanediamine suberate structure (Deg);

dihedral angle information in the pentanediamine suberate structure of FIG. 11 (Deg);

figure 12 hydrogen bond information in the pentanediamine suberate structure (Angstrom, Deg);

FIG. 13 characterization of the product;

figure 14 stability experiment.

Detailed Description

The process for the preparation of the pentanediamine suberate crystalline powder and the composition of the present invention, to which the present invention relates, is further illustrated by the following non-limiting examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the present invention.

Example 1:

to 100mL of 95% ethanol aqueous solution (ethanol volume fraction: 95%), 15.00g of pentamethylenediamine was added, and the mixture was sufficiently stirred to form an ethanol aqueous solution of pentamethylenediamine. Adding 27.00g of suberic acid solid into 350mL of anhydrous ethanol water solution to form an ethanol solution of suberic acid, mixing the suberic acid solid and the ethanol solution of suberic acid in a 500mL crystallizer, controlling the temperature at 25 ℃, stirring for 48h to generate a white crystal substance, discharging the white crystal substance into a tank, performing solid-liquid separation in a suction filtration mode, washing the solid with 150mL of 95% ethanol, drying the solid by blowing for 3h, maintaining the temperature at 60-80 ℃ to obtain pentanediamine suberate crystal powder, wherein the crystal structure is shown in figures 2 and 3, the detailed crystallographic data is shown in figure 8, and the crystal structure is C₁₃H₂₈N₂O₄Monoclinic system, C2/C space group,

α is 90.00 °, β is 117.673(4 °), γ is 90.00 °, unit cell volume

The minimum asymmetric unit number Z in the unit cell was 4, no water of crystallization was contained, and 1 pentanediamine cation and 1 suberic acid anion were contained in the minimum asymmetric unit thereof, as shown in fig. 1. The detailed data of the crystal structure, i.e., bond length information, is shown in fig. 9, bond angle information is shown in fig. 10, dihedral angle information is shown in fig. 11, and hydrogen bond information is shown in fig. 12. The thermogravimetric analysis pattern of the crystalline powder is shown in fig. 5 and fig. 6: an endothermic peak at 99.34 ℃ with a small weight loss step, at which time the loss of water or residual solvent on the surface of the crystalline powder begins; after 142.65 ℃ the product began to melt and decomposed. The diffraction pattern of the crystalline powder with respect to CuK α rays as characteristic X-rays is shown in fig. 4, and the specific diffraction data is shown in fig. 7. When the water-soluble organic silicon dioxide is prepared into an aqueous solution with the mass fraction of 5%, the pH value of the system is 5.4. The powder has good granularity, fluidity and stability.

Example 2:

30.00g of pentamethylene diamine was added to 100g of methanol and sufficiently stirred to form a pentamethylene diamine methanol solution. Putting 51.15g suberic acid into 500g methanol, dripping into a pentamethylene diamine methanol solution at the flow rate of 2mL/min at the temperature of 25 ℃, crystallizing under the stirring state, monitoring the pH change in the process, adding 0.15g of seed crystal at the pH of about 11.0, suspending the flow addition, growing the crystals for 3 hours, dripping the suberic acid methanol solution into a crystallization system at the flow rate of 0.5mL/min, continuing stirring for 2 hours after the complete flow addition is finished, discharging the solution into a tank, performing solid-liquid separation of crystal slurry through suction filtration, washing with 80-100 mL of ethanol, and performing vacuum drying at the temperature of 45 ℃ for 8 hours to obtain pentamethylene diamine suberate salt crystal powder, wherein the X-ray diffraction pattern of the powder is basically shown in figure 4. When the water-soluble organic silicon dioxide is prepared into an aqueous solution with the mass fraction of 5%, the pH value of the system is 7.5. The powder has good granularity, fluidity and stability.

Example 3:

50.00g of suberic acid was dissolved in 500g of isopropanol to give a homogeneous suberic acid isopropanol solution, which was then transferred into a 1000mL crystallizer. 35.00g of pentanediamine was dissolved in 300mL of a 95% aqueous acetone solution (acetone 95% by volume) to form an aqueous pentanediamine acetone solution. And then dripping the pentanediamine acetone aqueous solution into an isopropanol suberate solution by a pump in a mode of 2mL/min, adding 0.3g of seed crystal when the amount of the added pentanediamine is 15% of that of the suberic acid, adding the rest pentanediamine acetone aqueous solution in a mode of 0.2mL/min, wherein the whole process is carried out under a stirring state, controlling the rotating speed at 250-400 rpm and the temperature at 15 ℃, when the complete flow addition is finished, finishing crystallization, discharging the mixture into a tank for solid-liquid separation, washing a filter cake by 100mL of isopropanol, and placing the filter cake in a vacuum drying mode at 35-45 ℃ for 4 hours to obtain pentanediamine suberate salt crystal powder, wherein the X-ray diffraction pattern of the powder is basically shown in figure 4. When the water-soluble organic silicon dioxide is prepared into an aqueous solution with the mass fraction of 5%, the pH value of the system is 9.0. The powder has good granularity, fluidity and stability.

Example 4:

in an aqueous solution containing 50g/L of pentanediamine, a film evaporator or a rotary evaporation concentrator is used for concentrating the aqueous solution by 8 times, namely 1/8 of the volume of the concentrated aqueous solution which is equal to the original volume is placed in a crystallizer, the temperature is reduced to 15 ℃ under the stirring state, absolute ethyl alcohol at 15 ℃ which is 3 times of the volume of the feed liquid is added, the absolute ethyl alcohol is fully and uniformly mixed, suberic acid solid is added, the adding amount is equivalent to the mole number of the pentanediamine in the system, stirring and crystallization is carried out for 72 hours, solid-liquid separation is carried out in a tank, acetone with the volume being 2 times of the volume of the feed liquid is used for washing, and then vacuum drying is carried out for 10 hours at 60 ℃, so that pentanediamine suberic acid crystalline powder is obtained, wherein the. The water content of the powder is 0, and when the powder is prepared into an aqueous solution with the mass fraction of 5%, the pH value of the system is 6.8. The powder has good granularity, fluidity, stability, and no odor.

Example 5:

68.20g of suberic acid is dissolved in 550g of n-propanol to form a uniform suberic acid n-propanol solution, then one or more of ethyl acetate, ethyl formate, methyl acetate and isopropanol are added into the solution in an amount of 250mL, and the solution is transferred into a 2000mL crystallizer. 20.00g of pentamethylene diamine was dissolved in 350mL of ethyl formate to form a pentamethylene diamine ethyl formate solution. And then dripping the ethyl pentanediaminecarboxylate solution into the suberic acid solution by a pump in a mode of 1mL/min, adding 0.4g of seed crystals when the amount of the added pentanediamine is 15% of the amount of the suberic acid substance, controlling the temperature at 40 ℃, continuing stirring for 8 hours when the complete flow addition is finished, finishing crystallization, performing solid-liquid separation in a tank, washing a filter cake by 200mL of anhydrous methanol, and placing the filter cake at 70 ℃ for vacuum drying for 2 hours to obtain pentanediaminecarboxylate crystal powder, wherein the X-ray diffraction pattern of the powder is basically shown in figure 4. When the aqueous solution is prepared into an aqueous solution with the mass fraction of 5%, the pH value of the system is 4.1-6.5.

Example 6:

42.63g of suberic acid is dissolved in 400g of n-propanol-DMSO solution (the volume ratio of n-propanol to DMSO is 4: 1) to form a uniform suberic acid solution, then one or more of butanone, petroleum ether and tetrahydrofuran are added, the addition amount is 100mL, and then the mixture is transferred into a 1000mL crystallizer. 50.00g of pentamethylene diamine was dissolved in 300mL of butanone to form a pentamethylene diamine butanone solution. And then directly pouring the solution of pentanediamine butanone into the solution of suberic acid under the stirring state, maintaining the temperature of the system at 30 ℃, rotating speed at 350r/min, stirring for 1.0h, removing the crystallization tank for solid-liquid separation, washing a filter cake with 100mL of anhydrous butanone, and drying under vacuum at 35-50 ℃ for 5h to obtain pentanediamine suberate crystal powder, wherein the X-ray diffraction pattern of the powder is basically shown in figure 4. The water content of the powder is 0, and when the powder is prepared into an aqueous solution with the mass fraction of 5%, the pH value of the system is 7.5-10.0.

Example 7:

the samples obtained in examples 1 to 6 were taken and tested for d₁₀，d₅₀Bulk density, tap density and solvent residue, which illustrate that the pentanediamine suberate product obtained by the process of the present invention has good granularity and flowability, and the organic solvent residue of the product is hardly detectable, and the result is shown in fig. 13.

The samples obtained in examples 1 to 6 were subjected to a stability test at 60 ℃ and tested for light transmission at 430nm at intervals of 48 hours, respectively, and the initial samples were used as controls, and as a result, as shown in FIG. 14, it was found that none of the samples obtained in the six examples had a change in color, and T was changed_430nmIs not provided withThe obvious reduction indicates that the obtained sample has good stability.

Claims

1. A crystal of pentanediamine suberate, characterized in that the molecular formula of the pentanediamine suberate is C₁₃H₂₈N₂O₄And crystal water is not contained, and the molecular structural formula is shown as formula II:

the crystal structure of the crystal belongs to a monoclinic system, C2/C space group,

α＝90.00°，β＝117.673(4)°，γ＝90.00°，

the minimum asymmetric unit number Z in the unit cell is 4, and the minimum asymmetric unit contains 1 pentanediamine cation and 1 suberic acid anion; having a diffraction pattern for diffraction analysis using CuK alpha rays as characteristic X-rays substantially as shown in figure 4.

2. The crystal of pentanediamine suberate salt of claim 1, wherein the crystalline powder has a bulk density of greater than 0.22 g/mL.

3. The crystal of pentanediamine suberate salt of claim 1, wherein the crystalline powder has a tap density greater than 0.25 g/mL.

4. Crystals of pentanediamine suberate salt according to claim 1, characterized in that the crystalline powder has a d of more than 30 μm₅₀。

5. Crystals of pentanediamine suberate salt according to claim 1, characterized in that the crystalline powder has a d of more than 11 μm₁₀。

6. The crystal of pentanediamine suberate salt according to claim 1, wherein the pH value of the system is 4.1-10.0 when the crystal is prepared into an aqueous solution with a mass fraction of 5%.

7. A composition comprising

(i) The crystal according to any one of claims 2 to 4, and

(ii) (a) suberic acid; or

(b) Pentanediamine.

8. The process for producing crystals of pentanediamine suberate salt according to claim 1, wherein pentanediamine suberate salt is crystallized from a solution containing dissolved pentanediamine and suberic acid; separating the crystals from the solution; the separated crystals were dried.

9. The method of claim 8, wherein the solution containing dissolved pentanediamine and suberic acid is prepared by any one of the following methods:

(i) adding suberic acid and pentanediamine into a solvent simultaneously;

(ii) adding suberic acid and pentanediamine into a solvent in sequence;

(iii) adding pentamethylene diamine into a solvent to form pentamethylene diamine solution; adding suberic acid to a solvent to form a suberic acid solution or to form a solution containing a portion of undissolved suberic acid solids; and then mixing the two.

10. The method according to claim 9, wherein the solvent comprises one or more of methanol, ethanol, water, n-propanol, ethyl acetate, ethyl formate, methyl acetate, isopropanol, acetone, methyl ethyl ketone, petroleum ether, and DMSO.